Title:
DEVICE FOR CONTROLLING A LIFT OR THE LIKE
United States Patent 3887039


Abstract:
A device for controlling a lift provided with a lift-car which is displaceable along a lift-shaft interconnecting a plurality of storeys, the device comprising drive means responsive to a control signal to displace the lift car along the shaft, a plurality of storey switch devices each associated with a respective storey and each arranged to generate a storey signal when the lift is displaced past the respective switch device, lift-call signal processor means provided with means to store lift-call signals for respective storeys and with stepping means having a respective stage corresponding to each storey, the processor means generating a halt signal when the stepping means reaches a stepping stage corresponding to a storey for which a lift-call signal is stored in the storage means. There is further provided first signal generator means responsive to an initiating signal to generate a control signal which increases towards a predetermined maximum value to control the acceleration of the lift and which -- during travel of the lift at its maximum speed -- is maintained at said predetermined maximum value, second signal generator means for generating a succession of retardation signals each of which initially has a respective maximum value and which decreases in value to correspond at any moment to the maximum lift-car speed permissible for the service of the next servable storey. Comparator means serve to compare the signal generated by the first signal generator with the respectively present retardation signal, the comparator means -- the absence of the halt signal -- being responsive to a predetermined difference in magnitude between the compared signals to generate a stepping pulse and -- in the presence of the halt signal -- to apply the respectively present retardation signal to the drive means, the stepping means being stepped on through a switching step on departure of the lift-car from its initial location at the start of each journey and being stepped on through a switching step in response to each stepping pulse generated by the comparator means. The second signal generator means is responsive to each stepping movement of the stepping means to generate a further retardation signal, wherein the second signal generator means comprises means for generating a series of distance-analogue signals each corresponding in magnitude to the distance between storeys immediately successive in the direction of travel of the lift car, means for connecting successive ones of the distance-analogue signals in a stepwise manner to output means of the distance-analogue signal generator on the occurrence of each stepping movement of the stepping means, means for disconnecting the distance-analogue signals in a stepwise manner from the output means on the occurrence of each storey signal, integrator means for integrating a signal provided by an actual value signal generator mechanically coupled to the drive means, the output signal of the integrator means being of zero value at the beginning of each lift-car journey and being re-set to zero value on the occurrence of each storey signal, difference signal generator means to provide an output signal equal at each instant to the difference between the output signal of the distance-analogue signal generator and of the integrator means, and root former means having input means connected to the output of the difference signal generator means.



Inventors:
BONIEK KLAUS
Application Number:
05/459198
Publication Date:
06/03/1975
Filing Date:
04/08/1974
Assignee:
INVENTIO AKTIENGESELLSCHAFT
Primary Class:
International Classes:
B66B1/16; B66B1/24; (IPC1-7): B66B1/28
Field of Search:
187/29
View Patent Images:
US Patent References:



Primary Examiner:
Schaefer, Robert K.
Assistant Examiner:
Duncanson Jr., W. E.
Attorney, Agent or Firm:
Kleeman, Werner W.
Claims:
Accordingly, what is claimed is

1. A device for controlling a lift provided with a lift-car which is displaceable along a lift-shaft interconnecting a plurality of storeys, the device comprising drive means responsive to a control signal to displace the lift car along the shaft, a plurality of storey switch devices each associated with a respective storey and each arranged to generate a storey signal when the lift is displaced past the respective switch device, lift-call signal processor means provided with storage means to store lift-call signals for respective storeys and with stepping means having a respective stepping stage corresponding to each storey, the processor means generating a halt signal when the stepping means reaches a stepping stage corresponding to a storey for which a lift-call signal is stored in the storage means, first signal generator means responsive to an initiating signal to generate a control signal which increases towards a predetermined maximum value to control the acceleration of the lift and which -- during travel of the lift at its maximum speed -- is maintained at said predetermined maximum value, second signal generator means for generating a succession of retardation signals each of which initially has a respective maximum value and which decreases in value to correspond at any moment to the maximum lift-car speed permissible for the service of the next servable storey, comparator means to compare the signal generated by the first signal generator with the respectively present retardation signal, the comparator means -- the absence of the halt signal -- being responsive to a predetermined difference in magnitude between the compared signals to generate a stepping pulse and -- in the presence of the halt signal -- to apply the respectively present retardation signal to the drive means, the stepping means being stepped on through a switching step on departure of the lift-car from its initial location at the start of each journey and being stepped on through a switching step in response to each stepping pulse generated by the comparator means, the second signal generator means being responsive to each stepping movement of the stepping means to generate a further retardation signal, wherein the second signal generator means comprises means for generating a series of distance-analogue signals each corresponding in magnitude to the distance between storeys immediately successive in the direction of travel of the lift car, means for connecting successive ones of the distance-analogue signals in a stepwise manner to output means of the distance-analogue signal generator on the occurrence of each stepping movement of the stepping means, means for disconnecting the distance-analogue signals in a stepwise manner from the output means on the occurrence of each storey signal, integrator means for integrating a signal provided by an actual value signal generator mechanically coupled to the drive means, the output signal of the integrator meane being of zero value at the beginning of each lift-car journey and being re-set to zero value on the occurrence of each storey signal, difference signal generator means to provide an output signal equal at each instant to the difference between the output signal of the distance-analogue signal generator and of the integrator means, and root former means having input means connected to the output of the difference signal generator means.

2. A device as defined in claim 1, wherein the distance-analogue signal generator comprises a plurality of parallel connected branch circuits, each branch circuit corresponding to a respective storey and each comprising a potentiometer, a relay controlled switch means and a resistor connected in series with one another to cause the electrical current flowing in each branch circuit when the respective switch means is rendered conductive to be proprotional to the distance separating the storey corresponding to that branch from the storey immediately successive in the direction of travel of the lift-car.

3. A device as defined in claim 2, wherein the distance-analogue signal generator comprises a further branch circuit connected in parallel with said first mentioned branch circuit, the further branch circuit comprising a series circuit of a potentiometer, a further relay controlled switch and a resistor, the further branch circuit being associated with a portion of the path of travel of the lift-car which is provided in front of each target storey and which is substantially smaller than the smallest interstorey distance, the further relay controlled switch being actuated at the beginning of travel of the car along said path portion and the integrator being re-set to its zero value simultaneously with such actuation.

4. A device as defined in claim 3, wherein said integrator means possesses a feedback circuit which comprises two parallel identical branch circuits each including a capacitor, the capacitor in the one identical branch circuit being discharged through a resistor by means of a first relay controlled two-way switch, and the capacitor in the other identical branch circuit being selectively connected in the feedback circuit by a second relay controlled two-way switch, both the first and the second relay controlled two-way switches being simultaneously switchable at the beginning of travel of the lift-car and during the passage of a storey by the lift car.

5. A device as defined in claim 4, comprising a third relay controlled two-way switch which is simultaneously switchable with the first and second relay controlled two-way switches and by means of which the voltage of the actual value signal generator is connectable to the input of the integrator via a resistive device.

6. A device as defined in claim 5, wherein the resistive device comprises a potentiometer.

7. A device as defined in claim 4, wherein the integrator is resettable to its zero value by actuation of the first relay controlled two-way switch simultaneously with the opening of contacts of any one of the relay controlled switch means in the branch circuits of the distance-analogue signal generator.

8. A device as defined in claim 1, wherein the comparator means is responsive to compared signals of substantially equal value to generate a stepping pulse.

Description:
BACKGROUND OF THE INVENTION

The present invention relates to a new and improved device for controlling a lift or elevator with a speed-regulated drive.

In the case of lifts with small travel speed the nominal travel speed is reached during each journey independently of the travel distance. Thus, the braking path possesses a constant length, and the application of the brake occurs independently of the departure storey, always at the same path point in front of the target storey. This path point is mostly marked by a shaft vane disposed in the lift shaft at a location removed from the target storey by the length of the braking path.

In the case of lifts with larger travel speed, the nominal travel speed is not reached in the case of particular short journeys where the sum of the acceleration and retardation paths corresponding to the nominal travel speed is greater than the distance between departure and target storey. In this case the braking path no longer possesses a constant length, and the brake application ensues in dependence upon the departure storey at different path points in front of the target storey.

Account is taken of this circumstance in the case of most lifts for greater travel speeds in that there are provided two or three graduated nominal travel speeds, and for each journey there is selected the highest travel speed still attainable at the relevant travel path. In this case, however, the same nominal travel speed is associated with a whole series of journeys of different travel paths. Since the choice of the nominal travel speed values must be undertaken in such a manner that each graduation value is coordinated with the shortest travel path of the corresponding series, all longer travel paths of this series are travelled under unfavorable conditions, i.e. with a relatively large expenditure in time. This disadvantage could theoretically be avoided in that an individual nominal travel speed would be associated with each possible journey stretch. However, this solution, for practical purposes, is not able to be carried out, because of the large expenditure, in particular also because of the large number of shaft vanes per storey.

There has already been proposed in this art a control system with only one large nominal travel speed, wherein the optimal travel speed is automatically set for each travel path. This system possesses a call storage which possesses a series of call memories associated with the storeys, a stepping mechanism which possesses a series of position units associated with the individual storeys, and a stop call indicator which generates a holding signal, when the stepping mechanism reaches a position, which corresponds to a storey, for which a call is stored in the call-store. During the departure, an ideal or reference value voltage increasing according to a determined acceleration law is delivered to the speed controlled drive, and simultaneously there is triggered a braking ideal or reference value voltage which decreases according to a determined retardation or deceleration law and which corresponds at any moment to the maximal speed permissible for the serving of the next storey. The stepping mechanism is thus stepped-on or indexed through one switching step to the position corresponding to the next following storey. As soon as the two reference value voltages have reached the same voltage value, and provided that there is present a holding signal from the stop call indicator, the braking reference value voltage is delivered to the drive. If at this moment, however, no holding signal is present, the stepping mechanism is indexed by one switching step, and there is simultaneously triggered a new braking reference value voltage, which decreases according to the determined retardation law and which at any moment corresponds to the maximal speed permissible for the serving of the next storey. This procedure is repeated for such length of time until the stop call indicator generates a holding signal.

With this arrangement there are computed at any moment the travel speed still permissible for the serving of the next possible stop storey and the associated braking reference value curve. Consequently, there arises such a large expenditure that the application of this principle is worthwhile at best in the case of high speed lifts.

Another known control arrangement constitutes a compromise between the expensive control system which provides an optimal speed for each journey, and the system provided with fixed speed stages or steps and which permits optimal speeds only for few journeys. With this control arrangement operating at two main travel speeds, a pulse sequence is generated directly after beginning of travel, this pulse sequence synchronously stepwise indexing a stepping mechanism and a counter, whereby the storeys lying in the direction of travel are scanned for the presence of a call. In the event that a call is ascertained by the stepping mechanism or upon attaining a pulse number which is greater by one than the number of the storeys travellable with a travel speed not exceeding a predetermined first main travel speed, then the pulse sequence is interrupted by the counter. After finding of a call by the stepping mechanism, the retardation or deceleration of the lift or elevator car begins through brake application start pulses which are delivered by shaft switches. If no call is present after the interruption of the pulse sequence, then the stepping mechanism is indexed until the finding of a call by brake application start pulses, which are associated with a second, larger main travel speed. By the evaluation of the counter setting there occurs the pre-selection of the braking reference value voltage, which corresponds to the travel speed setting itself, and the selection of the start pulse which is fed to the reference value setting device, and which is associated with the target storey and the chosen direction and speed.

The disadvantage of this control system resides in the fact that the first, smaller main travel speed is determined by the smallest storey distance, so that during certain journeys no optimal speeds are achieved. A further disadvantage resides in the fact that calls which occur after the start for journeys in the same direction of travel to storeys which lie within the selected travel path in certain cases no longer can be considered.

SUMMARY OF THE INVENTION

A primary object of the invention aims at the provision of a device for controlling a lift which is not associated with these drawbacks and wherein there can be realized optimum speeds for each journey with economically acceptable expenditure of equipment. According to the present invention there is provided a device for controlling a lift provided with a lift-car which is displaceable along a lift-shaft interconnecting a plurality of storeys, the device comprising drive means responsive to a control signal to displace the lift car along the shaft, a plurality of storey switch devices each associated with a respective storey and each arranged to generate a storey signal when the lift is displaced past the respective switch device. There is further provided lift-call signal processor means provided with means to store lift-call signals for respective storeys and with stepping means having a stage respectively corresponding to each storey, the processor means generating a halt signal when the stepping means reaches a stepping stage corresponding to a storey for which a lift-call signal is stored in the storage means, first signal generator means responsive to an initiating signal to generate a control signal which increases towards a predetermined maximum value to control the acceleration of the lift and which -- during travel of the lift at its maximum speed -- is maintained at said predetermined maximum value, second signal generator means for generating a succession of retardation signals each of which initially has a respective maximum value and which decreases in value to correspond at any moment to the maximum lift-car speed premissible for the service of the next servable storey, comparator means to compare the signal generated by the first signal generator with the respectively present retardation signal, the comparator means -- in the absence of the halt signal -- being responsive to a predetermined difference in magnitude between the compared signals to generate a stepping pulse and -- in the presence of the halt signal -- to apply the respectively present retardation signal to the drive means, the stepping means being indexed through a switching step on departure of the lift-car from its initial location at the start of each journey and being indexed through a switching step in response to each stepping pulse generated by the comparator means, and the second signal generator means being responsive to each stepping or indexing movement of the stepping means to generate a further retardation signal, wherein the second signal generator means comprises means for generating a series of distance-analogue signals each corresponding in mangitude to the distance between storeys immediately successive in the direction of travel of the lift car, means for connecting successive ones of the distance-analogue signals in a stepwise manner to output means of the distance-analogue signal generator on the occurrence of each stepping or indexing movement of the stepping means, means for disconnecting the distance-analogue signals in a stepwise manner from the output means on the occurrence of each storey signal, integrator means for integrating a signal provided by an actual value signal generator mechanically coupled to the drive means, the output signal of the integrator means being of zero value at the beginning of each lift-car journey and being re-set to zero value on the occurrence of each storey signal, difference signal generator means to provide an output signal equal at each instant to the difference between the output signal of the distance-analogue signal generator and the integrator means, and root former means having input means connected to the output of the difference signal generator means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 schematically illustrates the most important parts of a lift or elevator in conjunction with a control device embodying the invention;

FIG. 2 is a graphical representation of the course of the time- or path-dependent lift speed;

FIG. 3 is a circuit diagram of a path determining device or arrangement;

FIG. 4 is a block diagram of two control stages for controlling the storey distance relays of the path determining unit;

FIG. 5 is a circuit diagram of an ideal or reference value setting device;

FIG. 6 is a graphical representation of the course of the output voltages of a path determining unit and an integrator;

FIG. 7 is a graphical representation of the course of the output voltage of the path determining device or arrangement; and

FIG. 8 is a graphical representation of the course of the time- or path-dependent lift speed in greater detail than the showing of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in FIG. 1, reference character 1 designates an elevator or lift shaft, only part of which has been shown, and in which a lift car 2 is guided. The lift car or elevator cabin 2 is secured at a hoisting cable 4 driven by a speed regulated winding engine 3. This lift car 2 services a number of building storeys Sl to Tn, only three of which are conveniently shown in this FIGURE. Shaft doors disposed at these storeys are designated by reference characters Tl to Tn. The winding engine 3, a regulating device or arrangement 5, an actual value indicator or setting device 6 and an ideal or reference value indicator or setting device 7 form a regulating circuit arranged in usual sequence. The actual value indicator device 6 is a tachometer dynamo which is coupled with the drive shaft of the winding engine 3 and generates a voltage which is proportional to the drive speed. The reference value indicator or setting device 7, as explained more fully in the following description of FIG. 5, generates over the entire travel path of the lift or elevator car 2 an ideal or reference value voltage which is proportional to the desired drive speed and which increases during the acceleration as a function of time, remains constant during the journey at nominal travel speed, and decreases during the retardation or deceleration independence upon the path traversed or travelled by the lift-car 2. The actual value voltage and the referennce or ideal value voltage are compared in the regulating device or arrangement 5, and the differential voltage resulting therefrom is amplified. The drive speed of the winding engine 3 is controlled by means of this amplified differential voltage. A travel direction switching device 8 determines in known manner the polarity of the reference or ideal value voltage in accordance with the prevailing direction of travel. A path determining device or arrangement is designated by reference character 9, a control apparatus consisting of stepping or indexing mechanism 10.1 and a call processor 10.2 by reference character 10, and a logic circuit by reference character 11. The path determining arrangement 9 is connected at the input side via line LMl to LMn with storey switches Ml to Mn which are mounted at the storeys Sl to Sn and which switches are actuated during the travelling- past of the lift car 2. Furthermore, the path determining arrangement 9 is connected via lines LSl to LSn with the stepping mechanism 10.1 of the control apparatus 10 and also is connected via lines Lu2, Ld2 and Ldu with the logic circuit 11. The path determining arrangement 9 is also connected to the actual value indicator or setting device 6. The path determining arrangement 9 is connected at its output side with the reference value indicator device 7.

The control apparatus 10 is a known lift control apparatus, for instance as described in detail in Swiss patent 381 831 for a collective control, the disclosure of which is incorporated herein by reference. The call processor 10.2, in the case of n storeys, possesses a series of n memory elements which are associated with the car calls and which are actuatable via lines LCl to LCn by car call generators Cl to Cn disposed in the lift or elevator car 2. It further possesses a respective series of n-1 memory elements, which are associated with the upwards or the downwards storey calls and which are actuatable by upwards storey call generators Su1 to Sun-1 or downwards storey call generators Sd2 to Sdn via lines LSu1 to LSun-1 or LSd2 to LSdn. The stepping mechanism 10.1 displays n position units associated with the individual storeys, and is advanced or indexed by pulses generated in the logic circuit 11 via a line LF2 with a predetermined lead. Upon the presence of a call, the call processor 10.2 determines the direction of travel necessary to service this call and transmits the result via conductors Lu1, Ld1 to the logic circuit 11. It further generates an initiating departure signal which is likewise fed via a line LST1 to the logic circuit 11. During the journey, the stepping mechanism 10.1 is stepwise indexed. As soon as it has reached a position which corresponds to a storey, for which the associated memory element has stored a lift-car signal, there occurs the hold predetermination in which the call processor 10.2 generates a halt signal which is fed to the logic circuit 11 via a line LH.

The logic circuit 11 comprises an arrangement of digital logic coupling elements (not shown). It receives from the call processor 10.2 via the line LST1 a departure signal which, after checking all safety precautions necessary for a journey, is transmitted via a line LST2 to the reference or ideal value indicator device 7. Via a line LF1 the logic circuit 11 receives from the reference value indicator or setting device 7 a signal, which is only then transmitted via a line LF2 to the stepping mechanism 10.1 for its indexing through one switching or indexing step, when no hold predetermination is present. Moreover, the logic circuit 11 receives direction information via the lines Lu1 from the call processor 10.2, and it transmits such information via the lines Lu2, Ld2 to the travel direction switching device 8 and via the lines Lu2, Ld2 and Ldu to the path determination arrangement 9.

The control principle which is the basis of the circuit arrangement according to FIG. 1 is known from Swiss Pat. No. 479,479, the disclosure of which is incorporated herein by reference, and will be more fully explained with reference to FIG. 2. In this Figure, the path traversed by the lift or elevator car 2 is plotted along the abscissa and the speed v of the lift car 2 along the ordinate v. Further, the path points corresponding to the storeys are designated by S4 to S8 along the abscissa. The course of the speed during the acceleration phase of the lift or elevator is represented by the curve vb and that during the journey at constant speed by the curve vk, which corresponds to the maximal attainable travel speed vmax. The retardation or deceleration curves v5, v6, v7 and v8 show the respective course of an ideal or reference speed given by the ideal or reference value setting device 7 during the retardation phase, when the lift should stop at the path point S5, S6, S7 or S8 displaying the same index as the curve. The points of intersection of the ideal retardation curves v5, v6, v7 and v8 with the curves vb and vk are designated by reference characters A, B, C and D.

Upon departure of the lift car 2 from the storey S4, the stepping mechanism 10.1 is indexed to the storey S5, and simultaneously the reference or ideal value setting device 7 is started for the generation of the retardation curve v5. As soon as the lift car 2 reaches the point of intersection A of the curves vb and v5, there is checked whether a hold predetermination is present for the storey S5. If this is the case, then the retardation ideal value according to curve v5 is applied to control the speed of the lift, so that the lift is retarded or decelerated according to this curve v5 and comes to standstill at the storey S5. If, on the other hand, no hold predetermination is present, i.e. no hold signal is generated for the storey S5, then the stepping mechanism 10.1 is indexed further through one indexing or switching step to the storey S6, and simultaneously the reference value setting device 7 is started for the generation of the retardation or deceleration curve v6. The analogous procedure then repeats when the lift car reaches the points of intersection B, C and D.

Upon the arrival of a call, for example, for the storey S6 after the lift car 2 has travelled through point B, this call only then can be honored when the lift car 2 has ended its journey. However, if a call for the storey S6 arrives before reaching the point B, then it can still be considered by the lift. According to this operating principle all calls which therefore arrive during the journey up to the beginning of the retardation or deceleration phase of the desired storey still can be considered.

As will be evident from FIG. 3, the path determining arrangement 9 consists of a path determining unit 9.1 in which the storey distances are formed in the form of analogue currents, a computing or computer stage 9.2 in which there is determined the braking path in the form of an analogue voltage and delivered to an input 7.9 of the reference value indicator device 7, and a control device or arrangement 9.3 for controlling the path presetting unit 9.1.

The path determining unit 9.1 is composed of a number -- corresponding to the storey number n -- of parallel current branch circuits Sz1 to Szn. In the branches Sz1 to Szn there are connected in series a respective potentiometer PVl to PVn, a relay contact SVKl to SVKn and a resistor or resistance RV1 to RVn. The relay contacts SVK1 to SVKn are actuated by storey distance relays SVl to Svn which, on the one hand, are connected via a terminal 9.4 with the positive pole of a direct-current voltage source and, on the other hand, are connected via lines LVl to LVn with the control arrangement 9.3. The two outputs of the path pre-setting unit 9.1 are connected with two terminals 9.5 and 9.6.

The computer stage 9.2 receives the actual value voltage which is proportional to the drive speed, from the actual value indicator device 6 via two terminals 9.7 and 9.8. This voltage is applied via a bridge circuit B consisting of four relay contacts SUK1, SUK2, SDK1 and SDK2, to a potentiometer PR1. The tap of the potentiometer PR1 is connected via a potentiometer PR2 to the middle of a potential or voltage divider consisting of a resistance RR1 and a potentiometer PR3. The ends of this voltage or potential divider RR1 and PR3 are connected via a relay two-way contact SIKI with the input of an integrator I. Integrator I is constituted by an operation amplifier with suitable feedback, as such is employed in analogue computers. Its feedback circuit consists of two identical parallel branch circuits, each containing a capacitor CR1 or CR2, respectively. The two capacitors CR1 and CR2 are alternately discharged or short-circuited by means of a relay two-way contact SIK3 via a discharge resistor or resistance RR2. At any time the one or the other feedback branch can be switched-in via a relay two-way contact SIK2. The output of the integrator I is connected via a resistor RR3 with the input of difference generator or adder A. The adder A is likewise an operational or differential amplifier, such as is known from analogue computers, with suitable feedback. At the output terminals 9.5 and 9.6 of the path determining unit 9.1, which simultaneously constitute input terminals for the computer stage 9.2, there is connected in series a potentiometer PR4, a relay contact SEK and a resistor RR4. This connection forms a further branch circuit SzE which is parallel with branches Sz1 to S2n of the path determining unit 9.1. The terminal 9.5 is moreover connected with a stabilised direct-current voltage source 9.21, and the terminal 9.6 is connected with the input of the adder A. The feedback circuit of the adder A consists of two parallel branches, one of which includes a capacitor CR3 and the other a resistor RR5. Moreover, the output of the adder A is connected with a terminal 9.9, by means of which the voltage corresponding to the braking path is delivered to the root former 7.2.

The control device or arrangement 9.3 is composed of a number -- corresponding to the storey number -- of control stages 9.3.1 to 9.3.n which will be considered more fully during the description of FIG. 4. The control stages receive control pulses from the storey switches Ml to Mn via the conductors or lines LMl to LMn and from the stepping mechanism 10.1 via the conductors or lines LSl to LSn. Moreover, they receive travel direction information from the logic circuit 11 via the lines Lu2, Ld2, and a switch-off or cut-off signal via the line Ldu when no travel direction information is present. The switching pulses generated in the control stages 9.3.1 to 9.3.n for the storey distance relays SVl to Svn are transmitted to the path determining unit 9.1 via the lines LVl to LVn. The control stages are furthermore connected with one another by lines LSt2 to LStn.

According to FIG. 4, the control stages 9.3.1 to 9.3.n of the control arrangement 9.3 consist in each case of six NOR-elements N1 to N6, the NOR-elements N2 and N3 forming a NOR-memory G according to conventional circuit design. The line LM1 leads via the NOR-element N1 of the control stage 9.3.1 to an input of the NOR-element N2, which is provided with three inputs, the second input of which is connected with the line Ldu and the third input of which is connected with the output of the NOR-element N3. Of the two inputs of the NOR-element N3, one input is connected with the output of the NOR-element N2, while the line SL1 is connected with the other input. The output of the NOR-element N3 leads to an input of the NOR-element N5 which is provided with two inputs, the second input of the latter being connected with the line Ld2. Of the two inputs of the NOR-element N4, the one is connected with the line Lu2, while the other is connected via the line LSt2 with the output of the NOR-memory G of the control stage 9.3.2. The outputs of the NOR-elements N4 and N5 are connected to the two inputs of the NOR-element N6, the output of which, on the one hand, is connected via the line LV1 with the path determining unit 9.1 and, on the other hand, with ground.

The numbers at the inputs and outputs characterise the switching conditions of the NOR-elements. The first number indicates the signals at standstill, the second the signals at departure and the third the signals during travelling through a storey. As is usual in digital control technology a logic signal "1" signifies positive voltage and a logic signal "0" no voltage.

The voltages appearing at the outputs of the path pre-setting or determining unit 9.1, of the integrator I and of the adder A during operation of the lift are represented in FIGS. 6 and 7. In these FIGURES the path traversed by the lift or elevator car 2 as well as the path points S1 to S5 corresponding to the individual storeys are plotted in each case along the abscissa and the different voltages along the ordinate. In FIG. 6 the output voltage waveform of the path determining unit 9.1 is designated by USV, wherein USV1, USV1+USV2 and so forth represent the individual voltage steps. The voltage course -- negative in relation to the output voltage USV -- of the integrator I is designated by UI. In FIG. 7 there is shown the course of the output voltage UA of the adder A or of the path determining device or arrangement 9.

The above-described path determining arrangement 9 operates as follows:

At standstill of the lift car 2 at a storey (S1) the line LS1 carries the logic signal 1 and the line LM1 the logic signal 0. Since at the same time the line Ldu carries the switching-off signal 1, the logic signal 0 appears at the output of the NOR-memory G of the control stage 9.3.1. Negated travel direction signals 1 pass via the lines Lu2 and Ld2 to the inputs of the NOR-elements N4 and N5. The second input -- connected with the output of the NOR-memory G -- of the NOR-element N5 displays the signal 0. The output of the NOR-element N5 thus has the logic signal 0. Since the line LS2 carries the logic signal 0 and the line LM2 the logic signal 1, the output of the NOR-memory G of the control stage 9.3.2 displays the logic signal 1. This signal passes via the line LST2 to the second input of the NOR-element N4 of the control stage 9.3.1, the output of which thus displays the logic signal 0. The two inputs of the NOR-element N6, which are connected with the outputs of the NOR-elements N4 and N5, thus have the logic signals O. The output circuit of the NOR-element N6 is thus opened or non-conductive, the storey distance relay SV1 -- connected via the line LV1 -- of the path determining unit 9.1 is without current, and the relay contact SVK1 is opened or non-conductive.

The actual value indicator device 6 coupled with the winding engine 3 does not deliver any voltage to the terminals 9.7 and 9.8 of the computer stage 9.2 at standstill of the lift. Thus, the output voltage of the integrator I is also zero. Since the storey distance relays SV1 to SVn are without current, and thus no path determining voltages appear at the input of the adder A, the output voltage at the terminal 9.9 of the computer stage 9.2 is also zero.

During the departure of the lift car 2 from a storey (S1) the storey switch M1 closes and the stepping mechanism 10.1 is indexed to the next storey (S2). Consequently, the logic signal 1 arrives via the line LM1 and the logic signal 0 via the line LS1 at the control stage 9.3.1. Since at the same time the logic signal 0 is delivered via the line Ldu, the logic signal 1 appears at the output of the NOR-memory G. Negated travel direction signals 0 and 1 pass via the lines Lu2 and Ld2 to the inputs of the NOR-elements N4 and N5 respectively. Since the second input of the NOR-element N5 is connected with the output of the NOR-memory G, it likewise displays the logic signal 1. The output of the NOR-element N5 thus has the logic signal 0. Since the lines LS2 and LM2 conduct the logic signals 1, the output of the NOR-memory G of the control stage 9.3.2 displays the logic signal 0. This signal passes via the line LSt2 to the second input of the NOR-element N4 of the control stage 9.3.1, the output of which thus displays the logic signal 1. The two inputs of the NOR-element N6, which are connected with the outputs of the NOR-elements N4 and N5, thus carry the signals 1 and 0 respectively. The output circuit of the NOR-element N6 is thus closed, the storey distance relay SV1, connected via the line LV1 with such output circuit, of the path determining unit 9.1 is energised, and the relay contact SVK1 is closed. Consequently, there appears at the input of the adder A a voltage USV1 which corresponds to the distance between the first and second storey and which is determined by the potentiometer PV1 and the resistor RV1, the potentiometer PV1 serving for the exact setting of the required voltage value. During the journey the voltage -- corresponding to the instantaneous lift speed -- of the actual value indicator device 6 is continually fed to the integrator I via the terminals 9.7 and 9.8 and the bridge circuit B and integrated over the distance between two storeys. Depending upon the direction of travel, either the relay contacts SUK1, SUK2 or the relay contacts SDK1, SDK2 of the bridge circuit B are closed, whereby the actual value voltage always appears with the same polarity at the input of the integrator I. In order to keep the occurring integration errors small, the integrator I is set to zero at the beginning of a journey and during the travelling-through of a storey. For this purpose, the relay two-way contacts SIK1, SIK3 are switched-over, the capacitor CR1 or CR2, as the case may be, being discharged across the resistor RR2, while simultaneously the capacitor CR2 or CR1 is available for the integration. Deviations of the actual value voltage and the integration time-constants are compensated by means of the potentiometers PR1, PR2 and PR3. The relays SI1 to SI3, SU and SD necessary for the actuation of the relay contacts SIK1 to SIK3, SUKi, SUK2, SDK1 and SDK2, and the controls belonging thereto, are not further represented or more closely explained.

The output voltage UI of the integrator I is supplied via the resistor RR3 to the adder A and subtracted from the output voltage USV of the path determining unit 9.1. The amplified voltage difference UA thus appearing at the output of the adder A is transmitted via the terminal 9.9 to the root former 7.2 of the reference value setting or indicator device 7, where it is transformed into the braking ideal or reference value voltage.

During the travelling-through of the next storey (S2), the storey switch M2 is actuated. The line LM2 thus conducts the logic signal 0. Since the line LS2 already conducts the logic signal 0, the output of the NOR-memory G of the control stage 9.3.2 exhibits the logic signal 1. This signal passes via the line LSt2 to the input of the NOR-element N4 of the control stage 9.3.1, the output of which thus changes to the logic signal 0. Since the output of the NOR-element N5 exhibits without change the signal 0, the output of the subsequently connected NOR-element N6 has the logic signal 1. The storey distance relay SV1 connected via the line LV1 is thus de-energised and the relay contact SVK1 opened.

In order to achieve a high accuracy of moving-in of the lift car, shortly before reaching the target storey the integrator I is again set to its null or zero value and the actual value voltage integrated over the remaining path. At the beginning of this integration, relay contact SEK closes and switches the voltage USE, which corresponds to the remaining path and which is determined by the potentiometer PR4 and the resistor RR4, to the input of the adder A. The relay SE necessary for the actuation of the relay contact SEK and the control belonging thereto are not further shown or discussed.

According to FIG. 5, the reference value setting or indicator device 7 consists of a time-dependent ideal or reference value setter 7.1 for generating the acceleration ideal or reference value, a root former 7.2, which transforms its input magnitude into the path-dependent retardation ideal or reference value, and a speed comparator 7.3 which controls the transition from time-dependent or constant (corresponding to maximum speed) to path-dependent ideal or reference value voltage. The reference value setting or indicator device 7 possesses seven connecting terminals 7.4 to 7.10, the ideal or reference value voltage being removed at the terminal 7.5. A stabilised direct-current voltage source, which has not been particularly shown, is connected at the terminals 7.6, 7.7 and 7.8, zero potential being applied at the terminal 7.7, a positive potential at the terminal 7.6 and a negative potential of equal magnitude at the terminal 7.8.

The reference value voltage appears at the time-dependent reference value setter 7.1 across a capacitor CT1 which, on the one hand, is connected with the zero potential of the terminal 7.7 and, on the other hand, is connected via a potentiometer PT1 and a resistor RT1 with the collector of a transistor TT1 connected as a constant current source. The emitter of this transistor TT1 is connected via a resistor RT2 with the positive potential appearing at the terminal 7.6, while the base leads to the tap of a potentiometer PT2. The potentiometer PT2 is connected, on the one hand, with the positive potential appearing at the terminal 7.6 and, on the other hand, between a Zener diode ZT and a resistor RT3 which are connected in series and connected in circuit between the terminals 7.6 and 7.8. Between the potentiometer PT1 and the resistor RT1 there is connected a further capacitor CT2 which, on the other hand, is connected with the terminal 7.7, i.e. is at zero potential. The series connection of the resistor RT1 with the capacitor CT2 is bridged by means of a two-way contact STK which is actuatable by a relay ST, the rest contact terminal STK.1 of which is connected with the collector of the transistor TT1, while a connection or line leads from its working contact terminal STK.2 to the speed comparator 7.3. The relay ST is actuated by the departure signal delivered via the line LST2 to the terminal 7.4, the two-way contact STK switching over from the rest contact position (STK.1) into the working contact position (STK.2). The departure signal remains for such length of time and thus the two-way contact STK remains in the working contact position (STK.2) for such length of time until the lift has completed the corresponding journey, i.e. until the holding or stop brake of the lift is operated. A diode DT1 is connected between the resisor RT1 and the capacitor CT2. A diode DT2 connected with opposite polarity to the diode DT1 is connected by means of its second terminal with the tap of a potentiometer PT3 which is connected in circuit between the terminals 7.6 and 7.7. A resistor RT4 is inserted between the diodes DT1, DT2 and the negative potential appearing at the terminal 7.8.

The root former 7.2 serves for the transformation of the output voltage of the path determining arrangement 9. It consists of an operational or differential amplifier OW which is feedback connected in such a manner by means of non-linear elements that its output voltage alters with the root of the input voltage. The output voltage delivered via the terminal 7.9, of the path determining arrangement 9 is applied to the input of the operational amplifier OW. The output voltage, corresponding to the path-dependent reference or ideal value, of the root former 7.2 appears at the output of the operational amplifier OW. This output voltage is non-linearly related to the voltage input to the root former 7.2. The negative feedback occurs via parallel current branches which successively block during dropping of the voltage, the first two of which consist in each case of a resistor RW1 and RW2 respectively and a Zener diode ZW1 and ZW2 respectively, the third of a resistor RW3 and a diode DW3, and a last parallel branch is formed by a resistor RW4. Thus, the negative feedback of the operational amplifier OW becomes increasingly weaker during dropping of the input voltage, so that the gain or amplification increases.

The output voltage -- corresponding to the path-dependent reference or ideal value -- of the root former 7.2 is applied in the speed comparator 7.3 via a resistor RG1 to the base of a transistor TG1. The collector of the transistor TG1 is connected with the positive potential appearing at the terminal 7.6, while its emitter is connected via a resistor RG2 with the collector of a transistor TG2 connected as a constant current source. The emitter of the transistor TG2 is connected via a potentiometer TG1 with the negative potential appearing at the terminal 7.8. Its base is kept at constant potential by means of a series circuit, connected between the terminals 7.7 and 7.8, of a resistor RG3 and a Zener diode ZG. The speed comparator 7.3 is provided with two operational amplifiers OG1 and OG2 operating as triggers. The input 2 of the operational amplifier OG1 is connected via a resistor RG4 with the emitter of the transistor TG1 and via a closing contact SGK of a relay SG with the output of the time-dependent reference value setter 7.1 leading to the terminal 7.5. The input 3 of the operational amplifier OG1 is directly connected at the output of the time-dependent reference value indicator or setter 7.1. The output of the operational amplifier OG1 is connected with the input of a NOR-element NG1, the output of which, on the one hand, is connected with the zero potential appearing at the terminal 7.7 and, on the other hand, is connected via the relay SG with the terminal 7.4. The input 2 of the operational amplifier OG2 is connected via a resistor RG5 and the resistor RG2 with the emitter of the transistor TG1, while the input 3 thereof is connected with the output of the time-dependent reference or ideal value setter 7.1. The output of the operational amplifier OG2 is connected via a NOR-element NG2 with the terminal 7.10. A voltage divider consisting of three resistors RG6, RG7 and RG 8 is connected between the positive potential appearing at the terminal 7.6 and the negative potential appearing at the terminal 7.8. A connection which is connected between the resistors RG6 and RG7 leads to the working contact terminal STK.2 of the time-dependent reference or ideal value setter 7.1. A diode DG1 is connected in circuit between the resistors RG7 and RG8 and the input 2 of the operational amplifier OG1. With the working contact setting (STK.2) of the two-way contact STK there thus appears an exactly defined potential at the input 2 of the operational amplifier OG1. Connected in parallel with the resistor RG2 is a potentiometer PG2, the tap of which is connected via a diode DG2 with the collector of the transistor TT1 of the time-dependent ideal value indicator or setter 7.1. A diode DG3 is, on the one hand, likewise connected with the collector of the transistor TT1 and, on the other hand, via a resistor RG9 with the collector of the transistor TG2.

The mode of operation of the reference value setting or indicator device 7 is more fully explained hereinafter with reference to FIG. 8. In this Figure, the path s traversed by the lift car 2 as well as the path points S1 to S6 corresponding to the individual storeys are plotted along the abscissa, and the reference or ideal value voltage Us appearing at the terminal 7.5 of the reference value setting or indicator device 7 or the speed v -- corresponding to it -- of the lift car 2 along the ordinate.

In the reference value setting device 7, at standstill of the lift, when the supply voltage source is switched-on, the capacitors CT1 and CT2 are short-circuited via the two-way contact STK, so that the capacitor voltages are zero. The actual value indicator or setting device 6 coupled with the winding engine 3 furnishes no voltage to the inputs 9.7 and 9.8 of the path determining device or arrangement 9, so that also its output 9.9 or the input 7.9 of the root former 7.2 and thus also the output 7.5 of the reference value setting device 7 are zero.

As soon as a departure signal is delivered via the line LST2 to the terminal 7.4, the relay ST is energised and the two-way contact STK is switched over into the working contact position (STK.2). The capacitors CT1 and CT2 are now charged via the transistor TT1 with constant current, the charging current being settable by means of the potentiometer PT2. The charging of the capacitor CT2 occurs via the resistor RT1, while the charging of the capacitor CT1 occurs via the resistor RT1 and the potentiometer PT1. Consequently, there occurs a delay of the voltage rise at the capacitor CT1, which brings about a rounding or smoothing of the voltage course at the beginning of the charging operation, which can be adjusted by means of the potentiometer PT1. The voltage course USb at the output 7.5 of the reference value setting device 7 now linearly increases as a function of time, there being attained an approximately constant acceleration of the lift or elevator car 2.

When the voltage at the capacitor CT2 reaches the value set at the potentiometer PT3, then the diode DT1 conducts and charging of the capacitor CT2 is interrupted. The capacitor CT1 reaches this voltage peak somewhat later on in time owing to the time-constant determined by the components CT1 and PT1, whereby the voltage ascent transforms with a rounded or smoothed portion R1 (FIG. 8) into a constant voltage course USk, corresponding to the maximum constant travel speed of the lift car 2. The diode DT2 ensures that the charging current will be removed via the resistor RT4 at the negative potential of the terminal 7.8.

The output voltage UA of the path determining arrangement 9 and delivered to the root former 7.2, possesses a linearly decreasing course as a function of the path through which the left car 2 has moved. As is known, a good travelling comfort is realized if the deceleration or retardation is also constant as much as possible over the entire braking path. In other words, the reference voltage value us and the speed v corresponding thereto must parabolically decrease as a function of the path s according to the equation v = K s. The output voltage UA of the path determining device or arrangement 9 is thus transformed at the root former 7.2 by means of the operational amplifier OW and the non-linear negative feedback elements ZW1, ZW2, DW3 into a parabolic-shaped reference value voltage USv, wherein especially for realizing a steep and defined termination the feedback in the last branch is carried out in the last branch by means of a linear resistor RW4. The thus-occurring slight falsification of the parabolic-shape at the end of the curve can be accepted without disadvantage and in some instances is even desirable.

According to the description of the control principle on the basis of FIG. 2 the starting time point for the decreasing path-dependent reference value voltage of the deceleration phase coincides with the starting time point of the increasing time-dependent reference value of the acceleration phase of the lift car 2. At the speed comparator 7.3 there is now compared the momentary value of the time-dependent reference value voltage USb with the momentary value of the path-dependent reference value voltage USv. The time-dependent reference or ideal value voltage USb is thus delivered to the inputs 3 of the operational or differential amplifiers OG1 and OG2 acting as triggers, while the path-dependent reference value voltage USv tapped-off the emitter of the transistor TG1 is delivered, on the one hand, via the resistor RG4 and, on the other hand, via the resistors RG2 and RG5 to the inputs 2 of the operational amplifiers OG1 and OG2 respectively. The voltage drop URG2 occurring at the resistor RG2 is kept constant by means of the difference of the two reference or ideal value voltages USb, USv has dropped to the value of the voltage drop URG2, then the operational amplifier OG2 switches. The logic signal 1 thus appears at its output, and the logic signal 0 at the output of the NOR-element NG2 connected thereafter. This signal arrives via the line LF1 at an input of a NOR-element NL of the logic circuit 11. Since also the other input -- connected with the line LH -- of the NOR-element NL displays the signal 0 when a hold predetermination is not present, thus the logic signal 1 appear at the output of this NOR-element. In consequence of this, a pulse is conducted via the line LF2 connected with the output of the NOR-element NL to the stepping mechanism 10.1, and the latter is further indexed one step.

Consequently, an additional voltage corresponding to the relevant storey distance is applied by the path determining arrangement 9 to the input of the root former 7.2. As a result thereof, the path-dependent reference value voltage of the retardation phase for the second next storey appears at the output of the root former 7.2. The difference between the ideal value voltages USB and USv thus again becomes substantially greater than the voltage drop URG2, so that the output of the operational amplifier OG2 again displays the logic signal O and the logic signal 1 appears at the output of the NOR-element NG2.

However, if there is present a hold predetermination signalled by the call processor 10.2 via the line LH to the logic circuit 11, then the signal 1 appears at the corresponding input of the NOR-element or gate NL. Since the logic signal O delivered by the speed comparator 7.3 via the line LF1 is present at the other gate input, the output of the NOR-element NL displays the logic signal 0. The stepping mechanism 10.1 is thus not further indexed, rather there is initiated the transition from the acceleration phase i.e. from the travel at constant speed to the retardation or deceleration phase. In this case, the path-dependent reference or ideal value voltage USv begins to fall towards zero, the diode DG3 becomes conductive and the capacitor CT2 discharges. The discharge current flowing via the transistor TG2 to the negative potential of the terminal 7.8 is, however, limited by the resistor RG9, so that the smoothing or rounding-off portion R2 (FIG. 8) of the time-dependent or constant reference value voltage USb or USk is first initiated. The diode DG2 begins to conduct, during further dropping of the path-dependent reference value voltage USv, at a point set by means of the potentiometer PG2. The capacitor CT2 is now discharged with low resistance via the tap of the potentiometer PG2. The discharge of the capacitor CT1 follows with a delay governed by the time-constant provided by the components CT1 ×PT1. The rounding-off R2 (FIG. 8) of the time-dependent or constant reference value voltage USb or USk is thereby further continued until it reaches the intersection with the path-dependent reference value voltage USv. At this moment the operational amplifier OG1 switches, so that a logic signal 1 appears at its output, whereupon the relay SG -- disposed in the switching circuit of the NOR-element NG1 -- responds and closes its contact SGK. The reference or ideal value voltage us at the terminal 7.5 now follows the curve USv of the path-dependent retardation reference or ideal value. At the path point S5 (FIG. 8) the reference value voltage us becomes zero, the holding brake of the lift is operated and the reference value setting device 7 is again displaced into the starting condition.

The arrangement or system designed according to the invention will be now more closely explained hereinafter with reference to a lift journey example:

Let it be assumed that the lift car 2 is situated at the storey S1 and there appears a call for the storey S5. At the moment of departure a pulse is transmitted from the call processor 10.2 to the stepping or indexing mechanism 10.1, so that such further indexes to the storey S2, whereupon the storey distance relay SV1 of the path determining unit 9.1 is energized. Thereafter the voltage USV1 (FIG. 6) corresponding to the distance between the first and second storey appears at the output of the path determining unit 9.1. Since the output of the integrator I of the computer stage 9.2 is zero at the starting point in time, there appears at the output of the adder A of the computer stage 9.2 the voltage UA1 (FIG. 7) which is equal to the voltage USV1 at the output of the path determining unit 9.1. The output UA1 of the adder A or of the path determining arrangement 9 arrives at the root former 7.2 of the reference or ideal value setting device 7 and appears at its output as the initial value of the path-dependent reference or ideal value voltage course USv for the storey S2 (FIG. 8). During the travel of the lift or elevator car 2, the output voltage UI (FIG. 6) of the integrator I increases as a function of the path or distance. The voltages UI are now continuously substracted from the voltages USV of the path determining unit 9.1 in the adder A, so that the output voltage UA of the adder A initially linearly decreases. This linear voltage course UA is transformed in the root former 7.2 into the parabolically extending path-dependent reference or ideal value voltage course USv (FIG. 8). During the further course of the journey, the decreasing reference value voltage course USv and the increasing reference value voltage course USb approach one another up to a voltage difference URG2. At this position, which for reason of the travelling comfort of the passengers is advanced or forwardly located in relation to the point of intersection A of FIG. 2, there is checked whether there is present a hold predetermination for the storey S2.

Since in this example, however, it was assumed there is present a call for the storey S5, the braking operation of the lift car is not introduced, rather the indexing or stepping mechanism 10.1 indexes further to the storey S3, whereupon the storey distance relay SV2 is energised. The voltage USV1 + USV2, which now appears at the output of the path determining unit 9.1 and which corresponds to the distance between the first and third storey, is obtained from the addition of the two voltages USV1 and USV2. There simultaneously appears at the output of the adder A a voltage UA2 (FIG. 7), which is obtained from the instantaneous or momentary value of the voltage course UA and the voltage USV2. This voltage arrives at the root former 7.2 and appears at its output as an initial value of the path-dependent reference or ideal value voltage course USv for the storey S3 (FIG. 8). Since during the further course of travel of the lift car 2 at the output voltage UI of the integrator I further increases as a function of the path or distance, the output voltages of the adder A and the root former 7.2 also again drop. Before the lift car 2 travels past the storey S2, there is obtained twice the voltage difference URG2 between the path-dependent reference or ideal value voltage course USv and the time-dependent ideal value voltage course USb, so that the above-described procedure is repeated twice. The output voltages of the path determining unit 9.1 and the adder A have now reached the values USV1 + USV2 + USV3 + USV4 and UA4 respectively, while the output voltage of the root former 7.2 is equal to the initial value of the path-dependent reference or ideal value voltage course USv for the storey S5. During travelling-past the storey S2, the integrator I is set to zero and the storey switch M2 is actuated, whereupon the storey distance relay SV1 of the path determining unit 9.1 is de-energised. Consequently, the output voltage course USV (FIG. 6) of the path determining unit 9.1 is reduced by the amout USV1. Since the output voltage UI of the integrator I directly before it is set to zero, is of the same magnitude, however possesses the opposite sign, the output voltage UA of the adder A does not alter. Shortly after travelling-through the storey S2, the nominal or rated travel speed vmax is reached. The time-dependent reference or ideal value voltage USk remains constant, while the lift car 2 continues to travel at the speed vmax. The output voltage UI of the integrator I again increases, and is again set to zero during travelling-through the storey S3. Simultaneously, the storey distance relay SV2 is switched-off by a pulse from the storey switch M3 via the lines LM3 and LSt3 (FIGS. 3, 4). The output voltage USV of the path determining unit 9.1 is diminished by the amount USV2, while the output voltages UA of the adder and USv of the root former 7.2 furthermore decrease linearly and parabolically, respectively. During the further course of the journey, the difference beween the path-dependent ideal or reference value voltage course USv for the storey S5 and the constant ideal or reference value voltage USk, becomes equal to the value URG2. Since for the storey S5, as is assumed in this journey example, a call is present, and thus a hold predetermination is present, the stepping mechanism 10.1 does not switch to the next storey, but the braking operation is introduced. During the travelling-through of the storey S4 and shortly before the storey S5, the integrator I is set to zero, and the corresponding voltages USV3, USV4 are switched-off by means of the storey distance relays SV3 and SV4. However, the output voltage USV of the path determining unit 9.1 has risen again -- at this point (FIG. 6) designated by P -- by closure of the relay contact SEK to a voltage USE corresponding to the remaining path. The integration error over this remaining path is small, so that for practical purposes no stopping error occurs. Upon completion of the journey at storey S5, the output voltage UI of the integrator I is of the same magnitude as the counter-connected voltage USE of the path determining unit 9.1, while the output voltage UA of the adder A and the output voltage USv -- serving as path-dependent reference or ideal value for the braking phase -- of the root former 7.2 are each zero.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.