Title:
AUTOMATIC DOOR CLOSER
United States Patent 3668737
Abstract:
An automatic door in which a closer shaft is connected at one end thereof to a door for turning movement therewith and carries in a housing in which the closer shaft is turnably mounted a cam fixed to the closer shaft. A pair of followers carried by a carriage are arranged to opposite sides of the shaft and cooperate with the cam to move the carriage in a first direction during turning of the shaft and cam to either side of a rest position in which the door is closed, and spring means cooperate with the carriage to be stressed to an increasing degree during movement of said carriage in this first direction, while damping means cooperate with the carriage to dampen the movement of said carriage in a direction opposite to said first direction.
US Patent References:
Double-acting hinge and check
Hubbs et al. - April 1928 - 1666903
Concealed overhead door closer
Blom - June 1964 - 3137888
AUTOMATIC UNIVERSAL DOOR CLOSER
Mittig et al. - October 1969 - 3474485
Adjusting stroke mechanism
Schlegel - June 1958 - 2838939
Double-acting hinge and check
Hubbs et al. - April 1928 - 1666903
Concealed overhead door closer
Blom - June 1964 - 3137888
AUTOMATIC UNIVERSAL DOOR CLOSER
Mittig et al. - October 1969 - 3474485
Adjusting stroke mechanism
Schlegel - June 1958 - 2838939
Application Number:
04/874599
Publication Date:
06/13/1972
Filing Date:
11/06/1969
View Patent Images:
Export Citation:
Assignee:
Dorken & Mankel KG (Ennepetal-Voerde, DT)
Primary Class:
Other Classes:
16/312
International Classes:
E05F3/10; E05F3/00
Field of Search:
16/55,53,60,153,151,49,54,56 74/55
Primary Examiner:
Gay, Bobby R.
Assistant Examiner:
Moore, Garry
Claims:
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims
1. An automatic door closer comprising, in combination, a housing; a closer shaft turnably mounted in said housing and having an end portion projecting beyond said housing and adapted to be connected to a door for turning movement therewith between a rest position in which the door is closed and turned positions in which the door is opened; a cam fixed in said housing to said shaft for turning movement therewith between said rest and said turned positions, said cam having two mirror-symmetrical halves forming at one end of said cam an indentation; an elongated carriage arranged in said housing for reciprocating movement substantially in direction of its elongation; only two followers carried by said carriage for cooperation with said cam, said two followers being respectively arranged on opposite sides of said shaft and substantially in a plane extending in the direction of movement of said carriage, one of said followers cooperating with said cam for moving said carriage in a first direction during turning of said cam to either side from said rest position; spring means in said housing operatively connected to said carriage and being biased to press said one follower against said cam, at least said one follower being a roller having an axis located in said plane and engaging in said rest position said cam in the region of said indentation in two spaced opposite zones symmetrically arranged with respect to said plane, said spring means being stressed to an increasing degreee during movement of said carriage in said first direction; and damping means connected to said carriage for damping movement of said carriage in the opposite direction under the influence of said stressed spring means.
2. An automatic door closer, as defined in claim 1, wherein said indentation has a radius of curvature smaller than that of said roller.
3. An automatic door closer as defined in claim 1, wherein the outline of each cam half outside said indentation follows substantially the shape of an involute.
4. An automatic door closer as defined in claim 1, wherein both followers are in the form of rollers.
5. An automatic door closer as defined in claim 4, wherein said carriage comprises a pair of substantially parallel plates connected by a pair of pins to each other, said pins respectively forming shafts on which said follower rollers are mounted between said plates.
6. An automatic door closer as defined in claim 5, wherein each of said plates is formed with an elongated slot having a pair of substantially parallel spaced side faces, said closer shaft extending through the slots in said plates for guiding said carriage for reciprocating movement.
7. An automatic door closer as defined in claim 5, wherein said damping means comprises a cylinder bore in said housing and a piston reciprocable in said cylinder bore, said spring means comprising a compression spring engaging at opposite ends thereof said piston and a portion of said housing between said piston and said carriage.
8. An automatic door closer as defined in claim 7, and including a connecting member connected at one end thereof to said piston and connected at the other end to a pair of laterally spaced portions of said carriage.
1. An automatic door closer comprising, in combination, a housing; a closer shaft turnably mounted in said housing and having an end portion projecting beyond said housing and adapted to be connected to a door for turning movement therewith between a rest position in which the door is closed and turned positions in which the door is opened; a cam fixed in said housing to said shaft for turning movement therewith between said rest and said turned positions, said cam having two mirror-symmetrical halves forming at one end of said cam an indentation; an elongated carriage arranged in said housing for reciprocating movement substantially in direction of its elongation; only two followers carried by said carriage for cooperation with said cam, said two followers being respectively arranged on opposite sides of said shaft and substantially in a plane extending in the direction of movement of said carriage, one of said followers cooperating with said cam for moving said carriage in a first direction during turning of said cam to either side from said rest position; spring means in said housing operatively connected to said carriage and being biased to press said one follower against said cam, at least said one follower being a roller having an axis located in said plane and engaging in said rest position said cam in the region of said indentation in two spaced opposite zones symmetrically arranged with respect to said plane, said spring means being stressed to an increasing degreee during movement of said carriage in said first direction; and damping means connected to said carriage for damping movement of said carriage in the opposite direction under the influence of said stressed spring means.
2. An automatic door closer, as defined in claim 1, wherein said indentation has a radius of curvature smaller than that of said roller.
3. An automatic door closer as defined in claim 1, wherein the outline of each cam half outside said indentation follows substantially the shape of an involute.
4. An automatic door closer as defined in claim 1, wherein both followers are in the form of rollers.
5. An automatic door closer as defined in claim 4, wherein said carriage comprises a pair of substantially parallel plates connected by a pair of pins to each other, said pins respectively forming shafts on which said follower rollers are mounted between said plates.
6. An automatic door closer as defined in claim 5, wherein each of said plates is formed with an elongated slot having a pair of substantially parallel spaced side faces, said closer shaft extending through the slots in said plates for guiding said carriage for reciprocating movement.
7. An automatic door closer as defined in claim 5, wherein said damping means comprises a cylinder bore in said housing and a piston reciprocable in said cylinder bore, said spring means comprising a compression spring engaging at opposite ends thereof said piston and a portion of said housing between said piston and said carriage.
8. An automatic door closer as defined in claim 7, and including a connecting member connected at one end thereof to said piston and connected at the other end to a pair of laterally spaced portions of said carriage.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to an automatic door closer having a closer shaft projecting from a housing and adapted to be at the projecting portion connected to a door so as to be moved with the latter from a rest position in which the door is closed to turned positions to opposite sides of the rest position in which the door is opened. A cam is fixedly connected in the interior of the housing to the closer shaft for turning movement therewith and this cam engages a pair of followers carried by a longitudinally movable carriage to which a spring arrangement acting as energy storage as well as the movable member of damping means are connected. In door closers of this type, it is necessary that the cam is positively engaged by the followers on the carriage since otherwise the door could be suddenly closed by a force acting directly on the same, for instance by hand or by a draft, because the damping device limits, especially during closing of the door only the speed of the carriage, but not directly the closing speed of the door. It is therefore necessary that the followers are arranged on the carriage and cooperate with the cam in such a manner so as to prevent that, during closing of the door, the cam overtakes the movement of the carriage. For this purpose, serves a follower arranged in the longitudinal plane of symmetry of the carriage which engages the cam only when during closing of the door the cam tends to overtake the movement of the carriage. So far it has been common practice with door closers of the aforementioned kind, in which the closer shaft is turnably in opposite directions from a rest position in which the door is closed, that is especially for automatic door closers applied to a swing door, to use for driving the carriage a pair of followers fixedly carried thereby of which, depending on the opening movement of the door in one or the other direction, one or the other of these followers will become active. These two followers are, in the constructions according to the known art, laterally displaced to opposite sides of a plane passing through the axis of the closer shaft and extending in direction of movement of the carriage, which plane is usually coinciding with the longitudinal plane of symmetry of the carriage. In such an arrangement, the turning movement of the door is necessarily limited to an angle considerably less than 180°. Such an arrangement is therefore unsuitable for many applications. In addition, the lateral displacement of the driving followers with respect to the longitudinal axis of the carriage, will require an undesirable increase of the necessary width of the housing of the closer. Furthermore, the lateral displacement of the followers with regard to the longitudinal plane of symmetry of the carriage, will cause considerable lateral pressure of the followers on the cam which will reduce the mechanical efficiency of the arrangement and increase the wear of followers and cam.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic door closer of the aforementioned kind, that is a door closer provided with a closer shaft turnable to opposite sides from a rest position and a carriage coupled to a spring arrangement as well to the movable member of a damping device, which combines an excellent mechanical efficiency with small dimensions, especially a small width of the closer housing.
With these objects in view, the automatic door closer, according to the present invention, mainly comprises a housing, a closer shaft turnably mounted in said housing and having an end portion projecting beyond said housing and adapted to be connected to a door for turning movement therewith between a rest position in which the door is closed and turned positions in which the door is opened, a cam fixed in the housing to the shaft for turning movement therewith between the aforementioned rest and turned positions, carriage means arranged in the housing for reciprocating movement in a direction substantially normal to the shaft, and a pair of followers carried by the carriage for cooperation with the cam, the followers are respectively arranged on opposite sides of the shaft and substantially in a plane extending in the direction of movement of the carriage, one of said followers cooperating with the cam for moving the carriage in a first direction during turning of the cam to either side from the rest position. The closer includes further spring means in the housing operatively connected to the carriage and biased to press the driving follower against the cam and at least the driving follower is in the form of a roller. The spring means are stressed to an increasing degree during movement of the carriage in the first direction, and damping means are connected to the carriage for damping the movement of the latter in a direction opposite to the first direction under the influence of the stressed spring means.
In such an arrangement, only a single driving roller is located opposite the follower which prevents an overtaking of the carriage by the closing door. This permits to construct the closing housing with a minimum width. In addition, in such an arrangement, the forces acting upon the carriage will always act substantially along the longitudinal plane of symmetry of the latter so that the means for guiding the carriage will have to take up only very small lateral forces. This will result in a simple, space saving guide for the carriage and a reduction of the wear of the cooperating parts. In addition, this arrangement permits the use of the door closer for controlling the turning movement of a door connected thereto through an angle of 180°.
In a preferred arrangement, according to the presend invention, the cam has two mirror symmetrical halves forming at one end of the cam in indentation, in which in the rest position of the cam, the one follower is located while engaging the cam in two symmetrically opposite zones. Such a construction of the cam will positively determine the rest position of the latter as well as the rest position of the closer shaft of the door connected thereto, whereby the form of the indentation can be chosen in such a manner that the rest position will be reached and maintained with the necessary closing moments. The outline of each cam half outside the indentation preferably follows substantially the shape of an involute.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal cross section through a door closer, according to the present invention, the cross section being taken along the line I--I of FIG. 2; and
FIG. 2 is a horizontal cross section of the door closer in which the cross section is taken along the line II--II of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The door closer, according to the present invention, shown in the drawing mainly comprises an elongated substantially prismatic housing 10 formed at one of the ends thereof with a cylinder bore 11 in which a damping piston 12 is reciprocably arranged. The damping piston is provided with the usual one-way valves and adjusting means for adjusting the degree of damping obtainable, and the valves and adjusting means are of standard construction well known in the art, and therefore, for simplification reason, not shown in the drawing. The cylinder bore 11 is at the outer end closed by a plug. A compression coil spring 13 abuts with one end on the inner face of the damping piston 12, whereas the opposite end of the spring 13 abuts against an abutment formed in the interior of the housing. An elongated member 14, extending through the interior of the coil spring 13, connects the piston 12 to a carriage 15 15 which, by the side faces of a longitudinal slot 16 formed therein, is directly or by means of a supporting element 17, movably guided on a cylindrical portion of a closer shaft 18. The closer shaft 18 is turnably mounted at its lower end in a bearing 19 mounted in the bottom of the housing 10, whereas an upper portion of the shaft is sealed in a cup-shaped cover 20 removably fixed in a corresponding opening of the top wall of the housing, by being for instance threadingly connected thereto, and this upper portion of the shaft is turnably mounted in a bearing 21 lodged in the cup-shaped cover. The closer shaft 18 projects with a portion in form of a trunnion 22 beyond the housing and the trunnion 22 serves for coupling a door directly or indirectly to the closer shaft. The connecting member 14 is connected at one end thereof to the damping piston 12 by means of a pin 23, whereas the other end of the member 14 is connected by a pair of pins 24 to laterally displaced portions of the carriage 15. The pins 24 are accessible from the outside after removal of the cover 22 to facilitate assembly of the elements.
The carriage 15 comprises a pair of vertically-spaced substantially parallel plates connected by a pair of pins 25 and 26 which respectively form shafts on which the follower rollers 27, respectively 28, are turnably arranged. The axes of the pins 25 and 26 which carry the rollers 27 and 28 in the space between the plates forming the carriage 15, are located in the longitudinal plane of symmetry of the carriage 15 and to opposite sides of the closer shaft 18. A cam 29 is located between the follower rollers 27 and 28 and engages the outer surfaces of the same. This cam, which is arranged between the plates of the carriage 15, is fixedly connected to the closer shaft 18 for turning therewith. The cam 29 has in plan view two mirror symmetrical halves forming at one end of the cam an indentation 30 which has a radius of curvature smaller than that of the roller 28 lodged therein, so that in the rest position of the cam, shown in the drawing, in which the door connected to the closer shaft 18 is in the closed position, the cam engages the roller 28 in two with respect of the longitudinal plane of symmetry of the carriage 15 oppositely located zones. In this way, the rest position of the cam 29 will be positively determined. The outline of each cam half, outside the indentation 30, follows substantially the shape of an involute.
During turning of the closer shaft 18 in one or the other direction from a rest position in which the door connected thereto is closed, the carriage 15 is moved towards the right, as viewed in the drawing, due to the cooperation of the cam 29 with the roller 28 abuting against the cam, which roller forms the driving follower. During such movement, the cylinder space to the left of the piston 12, as viewed in the drawing, will expand so that liquid, for instance oil contained in the interior of the housing, will be sucked thereinto, while the spring 13 will be compressed. The door is turnable through an angle of 180°, while the automatic door closer of the present invention will assure proper return of the door to the closed position. The compressed spring 13 drives through the piston 12, the connecting member 14, the carriage 15, the roller 28 and the cam 19, the closer shaft 18 and the door connected thereto in the direction for closing the door after the latter is released in a turned open position. If an outer force for instance the push of a hand, or air pressure, should act in closing direction on the door, a sudden closing of the same will still be prevented, since in such a case, the cam 29 will abut with a side face thereof on the roller follower 27, which therefore constitutes a check follower preventing sudden closing of the door. In order to protect in such a case, the closer arrangement against undue stresses, it is advantageous to limit the maximum braking action obtainable from the damping device in a known manner by means of an over-pressure valve which, for simplification reason, is not shown in the drawing.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of automatic door closers differing from the types described above.
While the invention has been illustrated and described as embodied in automatic door closer in which the cam fixedly connected to the closer shaft cooperates with a pair of followers located to opposite sides of the closer shaft and in a plane of symmetry of a carriage which carries the pair of followers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
The present invention relates to an automatic door closer having a closer shaft projecting from a housing and adapted to be at the projecting portion connected to a door so as to be moved with the latter from a rest position in which the door is closed to turned positions to opposite sides of the rest position in which the door is opened. A cam is fixedly connected in the interior of the housing to the closer shaft for turning movement therewith and this cam engages a pair of followers carried by a longitudinally movable carriage to which a spring arrangement acting as energy storage as well as the movable member of damping means are connected. In door closers of this type, it is necessary that the cam is positively engaged by the followers on the carriage since otherwise the door could be suddenly closed by a force acting directly on the same, for instance by hand or by a draft, because the damping device limits, especially during closing of the door only the speed of the carriage, but not directly the closing speed of the door. It is therefore necessary that the followers are arranged on the carriage and cooperate with the cam in such a manner so as to prevent that, during closing of the door, the cam overtakes the movement of the carriage. For this purpose, serves a follower arranged in the longitudinal plane of symmetry of the carriage which engages the cam only when during closing of the door the cam tends to overtake the movement of the carriage. So far it has been common practice with door closers of the aforementioned kind, in which the closer shaft is turnably in opposite directions from a rest position in which the door is closed, that is especially for automatic door closers applied to a swing door, to use for driving the carriage a pair of followers fixedly carried thereby of which, depending on the opening movement of the door in one or the other direction, one or the other of these followers will become active. These two followers are, in the constructions according to the known art, laterally displaced to opposite sides of a plane passing through the axis of the closer shaft and extending in direction of movement of the carriage, which plane is usually coinciding with the longitudinal plane of symmetry of the carriage. In such an arrangement, the turning movement of the door is necessarily limited to an angle considerably less than 180°. Such an arrangement is therefore unsuitable for many applications. In addition, the lateral displacement of the driving followers with respect to the longitudinal axis of the carriage, will require an undesirable increase of the necessary width of the housing of the closer. Furthermore, the lateral displacement of the followers with regard to the longitudinal plane of symmetry of the carriage, will cause considerable lateral pressure of the followers on the cam which will reduce the mechanical efficiency of the arrangement and increase the wear of followers and cam.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic door closer of the aforementioned kind, that is a door closer provided with a closer shaft turnable to opposite sides from a rest position and a carriage coupled to a spring arrangement as well to the movable member of a damping device, which combines an excellent mechanical efficiency with small dimensions, especially a small width of the closer housing.
With these objects in view, the automatic door closer, according to the present invention, mainly comprises a housing, a closer shaft turnably mounted in said housing and having an end portion projecting beyond said housing and adapted to be connected to a door for turning movement therewith between a rest position in which the door is closed and turned positions in which the door is opened, a cam fixed in the housing to the shaft for turning movement therewith between the aforementioned rest and turned positions, carriage means arranged in the housing for reciprocating movement in a direction substantially normal to the shaft, and a pair of followers carried by the carriage for cooperation with the cam, the followers are respectively arranged on opposite sides of the shaft and substantially in a plane extending in the direction of movement of the carriage, one of said followers cooperating with the cam for moving the carriage in a first direction during turning of the cam to either side from the rest position. The closer includes further spring means in the housing operatively connected to the carriage and biased to press the driving follower against the cam and at least the driving follower is in the form of a roller. The spring means are stressed to an increasing degree during movement of the carriage in the first direction, and damping means are connected to the carriage for damping the movement of the latter in a direction opposite to the first direction under the influence of the stressed spring means.
In such an arrangement, only a single driving roller is located opposite the follower which prevents an overtaking of the carriage by the closing door. This permits to construct the closing housing with a minimum width. In addition, in such an arrangement, the forces acting upon the carriage will always act substantially along the longitudinal plane of symmetry of the latter so that the means for guiding the carriage will have to take up only very small lateral forces. This will result in a simple, space saving guide for the carriage and a reduction of the wear of the cooperating parts. In addition, this arrangement permits the use of the door closer for controlling the turning movement of a door connected thereto through an angle of 180°.
In a preferred arrangement, according to the presend invention, the cam has two mirror symmetrical halves forming at one end of the cam in indentation, in which in the rest position of the cam, the one follower is located while engaging the cam in two symmetrically opposite zones. Such a construction of the cam will positively determine the rest position of the latter as well as the rest position of the closer shaft of the door connected thereto, whereby the form of the indentation can be chosen in such a manner that the rest position will be reached and maintained with the necessary closing moments. The outline of each cam half outside the indentation preferably follows substantially the shape of an involute.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal cross section through a door closer, according to the present invention, the cross section being taken along the line I--I of FIG. 2; and
FIG. 2 is a horizontal cross section of the door closer in which the cross section is taken along the line II--II of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The door closer, according to the present invention, shown in the drawing mainly comprises an elongated substantially prismatic housing 10 formed at one of the ends thereof with a cylinder bore 11 in which a damping piston 12 is reciprocably arranged. The damping piston is provided with the usual one-way valves and adjusting means for adjusting the degree of damping obtainable, and the valves and adjusting means are of standard construction well known in the art, and therefore, for simplification reason, not shown in the drawing. The cylinder bore 11 is at the outer end closed by a plug. A compression coil spring 13 abuts with one end on the inner face of the damping piston 12, whereas the opposite end of the spring 13 abuts against an abutment formed in the interior of the housing. An elongated member 14, extending through the interior of the coil spring 13, connects the piston 12 to a carriage 15 15 which, by the side faces of a longitudinal slot 16 formed therein, is directly or by means of a supporting element 17, movably guided on a cylindrical portion of a closer shaft 18. The closer shaft 18 is turnably mounted at its lower end in a bearing 19 mounted in the bottom of the housing 10, whereas an upper portion of the shaft is sealed in a cup-shaped cover 20 removably fixed in a corresponding opening of the top wall of the housing, by being for instance threadingly connected thereto, and this upper portion of the shaft is turnably mounted in a bearing 21 lodged in the cup-shaped cover. The closer shaft 18 projects with a portion in form of a trunnion 22 beyond the housing and the trunnion 22 serves for coupling a door directly or indirectly to the closer shaft. The connecting member 14 is connected at one end thereof to the damping piston 12 by means of a pin 23, whereas the other end of the member 14 is connected by a pair of pins 24 to laterally displaced portions of the carriage 15. The pins 24 are accessible from the outside after removal of the cover 22 to facilitate assembly of the elements.
The carriage 15 comprises a pair of vertically-spaced substantially parallel plates connected by a pair of pins 25 and 26 which respectively form shafts on which the follower rollers 27, respectively 28, are turnably arranged. The axes of the pins 25 and 26 which carry the rollers 27 and 28 in the space between the plates forming the carriage 15, are located in the longitudinal plane of symmetry of the carriage 15 and to opposite sides of the closer shaft 18. A cam 29 is located between the follower rollers 27 and 28 and engages the outer surfaces of the same. This cam, which is arranged between the plates of the carriage 15, is fixedly connected to the closer shaft 18 for turning therewith. The cam 29 has in plan view two mirror symmetrical halves forming at one end of the cam an indentation 30 which has a radius of curvature smaller than that of the roller 28 lodged therein, so that in the rest position of the cam, shown in the drawing, in which the door connected to the closer shaft 18 is in the closed position, the cam engages the roller 28 in two with respect of the longitudinal plane of symmetry of the carriage 15 oppositely located zones. In this way, the rest position of the cam 29 will be positively determined. The outline of each cam half, outside the indentation 30, follows substantially the shape of an involute.
During turning of the closer shaft 18 in one or the other direction from a rest position in which the door connected thereto is closed, the carriage 15 is moved towards the right, as viewed in the drawing, due to the cooperation of the cam 29 with the roller 28 abuting against the cam, which roller forms the driving follower. During such movement, the cylinder space to the left of the piston 12, as viewed in the drawing, will expand so that liquid, for instance oil contained in the interior of the housing, will be sucked thereinto, while the spring 13 will be compressed. The door is turnable through an angle of 180°, while the automatic door closer of the present invention will assure proper return of the door to the closed position. The compressed spring 13 drives through the piston 12, the connecting member 14, the carriage 15, the roller 28 and the cam 19, the closer shaft 18 and the door connected thereto in the direction for closing the door after the latter is released in a turned open position. If an outer force for instance the push of a hand, or air pressure, should act in closing direction on the door, a sudden closing of the same will still be prevented, since in such a case, the cam 29 will abut with a side face thereof on the roller follower 27, which therefore constitutes a check follower preventing sudden closing of the door. In order to protect in such a case, the closer arrangement against undue stresses, it is advantageous to limit the maximum braking action obtainable from the damping device in a known manner by means of an over-pressure valve which, for simplification reason, is not shown in the drawing.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of automatic door closers differing from the types described above.
While the invention has been illustrated and described as embodied in automatic door closer in which the cam fixedly connected to the closer shaft cooperates with a pair of followers located to opposite sides of the closer shaft and in a plane of symmetry of a carriage which carries the pair of followers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.