Title:
Swash drive
Kind Code:
A1


Abstract:
The invention relates to a swash drive for a high-pressure cleaning appliance, having a swash body which can be driven in rotation about an axis of rotation, and having a swash plate which is inclined in relation to the axis of rotation and on the face of which there can engage pistons of a piston-pump which are movable back and forth parallel to the axis of rotation, the swash body butting against a supporting plate via a supporting bearing and a swash-plate bearing being disposed between the swash body and the swash plate. In order to develop the swash drive such that it is possible to increase the inclination of the swash plate without any risk of damaging the supporting bearing, it is proposed according to the invention that the supporting bearing be configured as an angular-contact ball bearing, the swash body supporting the bearing balls of the supporting bearing on the outside.



Inventors:
Nathan, Robert (Backnang, DE)
Application Number:
11/801946
Publication Date:
11/29/2007
Filing Date:
05/11/2007
Assignee:
Alfred Kaercher GmbH & Co. KG (Winnenden, DE)
Primary Class:
International Classes:
F01B3/00
View Patent Images:



Primary Examiner:
KASTURE, DNYANESH G
Attorney, Agent or Firm:
Lipsitz & McAllister, LLC (MONROE, CT, US)
Claims:
1. Swash drive for a high-pressure cleaning appliance, having a swash body which can be driven in rotation about an axis of rotation, and having a swash plate which is inclined in relation to the axis of rotation and on the face of which there can engage pistons of a piston-pump which are movable back and forth parallel to the axis of rotation, the swash body butting against a supporting plate via a supporting bearing and a swash-plate bearing being disposed between the swash body and the swash plate, the supporting bearing being configured as an angular-contact ball bearing, and the swash body supporting the bearing balls of the supporting bearing on the outside.

2. Swash drive according to claim 1, wherein the supporting plate has a central opening which is bounded by a radially oriented inner flange which merges, via a cranked portion, into a radially oriented outer flange, the cranked portion, on the swash-body side, forming a bearing channel for the supporting bearing.

3. Swash drive according to claim 2, wherein, in relation to the axis of rotation of the swash body, the inner flange is offset with respect to the outer flange in the direction of the swash body.

4. Swash drive according to claim 1, wherein the swash body forms, on the supporting-plate side, a bearing channel for the supporting bearing and is followed by a collar which is oriented in the direction of the supporting plate and overlaps the bearing balls of the supporting bearing.

5. Swash drive according to claim 1, wherein the swash body forms a bearing channel on the swash-plate side and supporting-plate side in each case, the radial spacing between the base of the swash-plate-side bearing channel and the base of the supporting-plate-side bearing channel being smaller than the diameter of the bearing balls of the supporting bearing.

6. Swash drive according to claim 1, wherein the bearing balls of the swash-plate bearing differ in diameter from the bearing balls of the supporting bearing.

7. Swash drive according to claim 1, wherein the swash-plate bearing is configured as an angular-contact ball bearing.

8. Swash drive according to claim 7, wherein the swash body is configured, in an outer region, as a collar which is directed toward the supporting plate and, in a central region, as a protrusion which is directed toward the swash plate, the swash body forming in the transition region between the collar and the protrusion, on the supporting-plate side, a bearing channel of the supporting bearing and, on the swash-plate side, a bearing channel of the swash-plate bearing.

9. Swash drive according to claim 8, wherein the swash body is configured, in its central inner region, as a well-like depression with a base wall which is oriented parallel to the supporting plate and has a central opening.

10. Swash drive according to claim 7, wherein the swash plate forms a planar annular plate which merges, via a bent-around portion, into a collar which is directed toward the swash body, the bent-around portion forming, on the swash-body side, a bearing channel of the swash-plate bearing.

11. Swash drive according to claim 1, wherein mounted in the supporting plate is an electric motor, the motor shaft of which is mounted in a rotationally fixed manner on the swash body and is supported in a rotatable manner via the supporting bearing.

12. Swash drive according to claim 11, wherein the electric motor is configured as an external rotor motor with a stator, which is mounted on the supporting plate, and a rotor, which is fitted around the stator and is connected in a rotationally fixed manner to the motor shaft.

13. Swash drive according to claim 12, wherein the motor shaft is supported in a rotatable manner at two locations, namely on the stator, via a motor bearing, and on the supporting plate, via the supporting bearing.

14. Swash drive according to claim 12, wherein the motor shaft is supported in a rotatable manner only at one end, namely on the supporting plate, via the supporting bearing.

15. Swash drive according to one of claim 1, wherein the swash drive has a cup-like housing with a base wall and a circumferential wall projecting therefrom, the base wall having an opening and being clamped in between the supporting plate and the stator.

Description:

This application is a continuation of international application number PCT/EP2005/010998 filed on Oct. 13, 2005.

The present disclosure relates to the subject matter disclosed in international application number PCT/EP2005/010998 of Oct. 13, 2005 and German application number 10 2004 056 019.6 of Nov. 16, 2004, which are incorporated herein by reference in their entirety and for all purposes.

BACKGROUND OF THE INVENTION

The invention relates to a swash drive for a high-pressure cleaning appliance, having a swash body which can be driven in rotation about an axis of rotation, and having a swash plate which is inclined in relation to the axis of rotation and on the face of which there can engage the pistons of a piston-pump which are movable back and forth parallel to the axis of rotation, the swash body butting against a supporting plate via a supporting bearing and a swash-plate bearing being disposed between the swash body and the swash plate.

Such swash drives are known from WO 00/08335. They are used in high-pressure cleaning appliances in order to convert the rotary movement of a motor shaft into a back and forth movement of the pistons. By means of the pistons, it is then possible, on a periodic basis, for cleaning liquid, preferably water, to be taken in, subjected to pressure and discharged via a pressure line. If the delivery capacity of the high-pressure cleaning appliance is to be changed, then the stroke of the pistons can be changed for this purpose. A change in stroke can be achieved by the pistons butting against the face of the swash plate at a different radial spacing relative to the axis of rotation. The greater the radial spacing between the pistons and the axis of rotation of the swash body, the greater is the stroke which can be achieved by the pistons, the inclination of the swash plate remaining the same. An increase in the radial spacing between the pistons and the axis of rotation, however, requires considerable constructional reconfiguration of the piston pump.

As an alternative, for the purpose of changing the delivery capacity of the high-pressure cleaning appliance, the stroke of the pistons may be changed by altering the inclination of the swash plate, the radial arrangement in relation to the axis of rotation remaining the same. The greater the inclination of the swash plate in relation to the axis of rotation of the swash body, the greater is the piston stroke which can be achieved while the radial arrangement of the pistons remains the same. In the case of the inclination of the swash plate being changed, all that is required is for the construction of the piston pump to be adapted to the changed axial movements of the pistons. Such an adaptation can be carried out in a structurally straightforward manner. An increased inclination of the swash plate, requires however considerably greater tilting moments to be transmitted from the swash plate, via the swash bearing, to the swash body and from the latter, via the supporting bearing, to the supporting plate. The resulting radial forces can only be absorbed to a very limited extent by the conventional supporting bearings since there is a risk of the rolling-contact bodies of the supporting bearing yielding in the radial direction.

In order to support a swash plate on a swash body which is mounted in a rotationally fixed manner on a drive shaft, GB 976,608 A proposes a ball bearing with an inner raceway and an outer raceway. The inner raceway is connected in a rotationally fixed manner to the swash plate and the outer raceway is connected in a rotationally fixed manner to the swash body. The inner raceway is configured as a single part and has two bearing-running surfaces, whereas the outer raceway is configured in two parts and comprises a front raceway half and a rear raceway half, each of which has a bearing-running surface for the bearing balls of the ball bearing. The two raceway halves are enclosed by a bearing-carrying ring and support the bearing balls on the outside by way of their bearing-running surfaces.

Japanese specification JP 2002 147343 A discloses a swash plate which is supported on a housing wall via a rolling-contact bearing. The rolling-contact bearing has a front raceway and a rear raceway, as seen in the axial direction, each with a conical bearing-running surface for rolling-contact bodies disposed therebetween.

It is an object of the present invention to develop a swash drive of the type mentioned in the introduction in such a way that the inclination of the swash plate may be increased without any risk of damaging the supporting bearing.

SUMMARY OF THE INVENTION

This object is achieved according to the invention, in the case of a swash drive of the generic type, by the supporting bearing being configured as an angular-contact ball bearing, the swash body supporting the bearing balls of the supporting bearing on the outside.

According to the invention, the supporting bearing is configured as an angular-contact ball bearing and the bearing balls of the supporting bearing are supported by the swash body on the outside, as seen in the radial direction. It has been found that such a construction of the swash drive also allows relatively large radial forces to be reliably absorbed without the supporting bearing, or any other components of the swash drive, being damaged, so that the inclination of the swash plate may be increased. For example, the angle of inclination of the swash plate may be more than 14° in relation to the axis of rotation of the swash body.

The supporting plate preferably has a central opening which is bounded by a radially oriented inner flange which merges, via a cranked portion, into a radially oriented outer flange, the cranked portion forming, on the swash-body side, a bearing channel for the supporting bearing. This enables particularly cost-effective production of the swash drive since the supporting plate itself forms a bearing channel for the supporting bearing, so that it is possible to dispense with a separate manufacturing step for producing the bearing channel.

It is advantageous if, in relation to the axis of rotation of the swash body, the inner flange is offset with respect to the outer flange in the direction of the swash body. This enables particularly straightforward assembly of the supporting bearing since the cranked portion between the projecting inner flange and the set-back outer flange forms a centering aid for the supporting bearing, so that the ball-bearing raceway of the supporting bearing may be positioned on the supporting plate without any assembly aid.

The supporting plate may be configured, for example, as a sheet-metal part which is formed by deep drawing.

In an advantageous embodiment, the swash body forms, on the supporting-plate side, a bearing channel for the supporting bearing and is followed by a collar which is oriented in the direction of the supporting plate and overlaps the bearing balls of the supporting bearing. The swash body engages over the bearing balls of the supporting bearing by means of its collar, so that these bearing balls cannot yield in the radial direction. Accordingly, high radial forces can be reliably absorbed by the supporting bearing and the swash body.

It is particularly advantageous if the swash body forms a bearing channel on the swash-plate side and supporting-plate side in each case, the radial spacing between the base of the swash-plate-side bearing channel and the base of the supporting-plate-side bearing channel being smaller than the diameter of the bearing balls of the supporting bearing. The supporting surfaces which the swash body forms for the bearing balls of the swash-plate bearing and of the supporting bearing may have the same pitch-circle diameters. However, it may also be provided that the pitch-circle diameter of the supporting surface for the swash-plate bearing is smaller than the pitch-circle diameter of the supporting surface which the swash body forms for the supporting bearing. The difference in pitch-circle diameters is preferably selected such that the radial spacing between the bases of the bearing channels is smaller than the diameter of the bearing balls of the supporting bearing. This also makes it possible for the swash drive to be subjected to high mechanical loading in respect of radially oriented forces also.

Moreover, such a configuration enables cost-effective production of the swash body since the latter may preferably be configured as a sheet-metal part produced by deep drawing, the arrangement of the bases of the bearing channels which has been explained enabling good flow behavior of the material of the swash body.

It is advantageous if the bearing balls of the swash-plate bearing differ in diameter from the bearing balls of the supporting bearing. In particular, it may be provided that the diameter of the bearing balls of the swash-plate bearing is smaller than the diameter of the bearing balls of the supporting bearing.

While the supporting bearing is configured as an angular-contact ball bearing, the swash-plate bearing may be in the form of an axial ball bearing.

In a particularly preferred embodiment, however, it is provided that both the supporting bearing and the swash-plate bearing are in the form of angular-contact ball bearings. It is thus additionally easier to assemble the swash drive since the swash body forms a centering aid on which the ball-bearing raceway of the swash-plate bearing can be positioned without any assembly aid. Using two angular-contact ball bearings for the swash drive makes it possible, in combination with the bearing balls of the supporting bearing being supported on the outside by the swash body, for particularly large radial forces to be reliably absorbed, so that it is also possible to provide larger angles of inclination for the swash plate without the service life of the swash drive being adversely affected.

It is preferable for the swash body, in respect of its radial extent, to be configured, in an outer region, as a collar which is directed toward the supporting plate and, in a central region, as a protrusion which is directed toward the swash plate, the swash body forming in the transition region between the collar and the protrusion, on the supporting-plate side, a bearing channel of the supporting bearing and, on the swash-plate side, a bearing channel of the swash-plate bearing.

It has been found that this enables particularly cost-effective shaping of the swash body by means of deep drawing, the swash body being capable of being subjected to high mechanical loading and very good flow behavior of the material of the swash body being ensured during deep drawing.

The swash body may be reinforced mechanically by being configured, in its central inner region, as a well-like depression with a base wall which is oriented parallel to the supporting plate and has a central opening. In such a configuration of the swash body, the base wall is surrounded, on the swash-plate side, by an annular protrusion which, on its outer periphery, forms a bearing channel of the swash-plate bearing and merges, via a bent-around portion, into the collar of the swash body, the bent-around portion forming, on the supporting-plate side, a bearing channel of the supporting bearing.

The swash plate is preferably formed as a planar annular plate which merges, via a bent-around portion, into a collar which is directed toward the swash body, the bent-around portion forming, on the swash-body side, a bearing channel of the swash-plate bearing.

The swash plate may likewise be configured as a sheet-metal part which is formed by deep drawing.

In a particularly preferred embodiment of the swash drive according to the invention, mounted on the supporting plate is an electric motor, the motor shaft of which is mounted in a rotationally fixed manner on the swash body and is supported in a rotatable manner via the supporting bearing. The supporting bearing, in the form of an angular-contact ball bearing, in such an embodiment, does not just perform the function of supporting the swash body on the supporting plate; rather, in addition, the motor shaft of the electric motor is supported in a rotatable manner via the supporting bearing. This enables a particularly straightforward construction of the swash drive, which can be produced cost-effectively and can be assembled within a short period of time, because it is possible to dispense with a separate bearing for the motor shaft in the region of the supporting plate.

It is particularly advantageous if the electric motor is configured as an external rotor motor with a stator, which is mounted on the supporting plate, and a rotor, which is fitted around the stator and is connected in a rotationally fixed manner to the motor shaft. Using an external rotor motor enables the construction of the swash drive to be simplified further, the stator being mounted on the supporting plate—for example by means of connecting screws. The supporting plate thus forms an end flange of the electric motor, and the motor shaft is supported via the swash body and the supporting bearing.

It may be provided that the motor shaft is supported in a rotatable manner at two locations, namely, on the stator, via a motor bearing, and, via the supporting bearing, on the supporting plate. The support on the stator can be provided by means of a plain bearing or a rolling-contact bearing, in particular a ball bearing.

It is particularly advantageous if the motor shaft is supported in a rotatable manner only at one end, namely, via the supporting bearing, on the supporting plate. Such a configuration dispenses with a second bearing for the motor shaft; rather, the latter is supported only at one end and carries the rotor of the electric motor.

In a preferred embodiment, the electric motor is mounted on the supporting plate by the swash drive having a cup-like housing with a base wall and a circumferential wall projecting therefrom, the base wall having an opening and being clamped in between the supporting plate and the stator of the electric motor. In the case of such a construction, the supporting plate butts against the inside of the base wall and the stator of the electric motor butts against the outside of the base wall of the housing and, by virtue of the supporting plate being screw-connected to the stator, the base wall is clamped in between these two components, so that the latter are mounted on the housing of the swash drive in a releasably connectable manner. It is advantageous here if the supporting plate forms a positive fit with the housing by way of its outer periphery, because this allows the mechanical loading to which the swash drive can be subjected to be increased and simplifies assembly.

A more detailed explanation will be given by the following description of two preferred embodiments of the invention, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional view of a first embodiment of a swash drive;

FIG. 2 shows a schematic sectional view of a swash unit of the swash drive fro FIG. 1;

FIG. 3 shows a schematic sectional view of a second embodiment of a swash drive; and

FIG. 4 shows a schematic sectional view of an alternative swash unit for the swash drives from FIGS. 1 and 3.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates, schematically, a swash drive 10 for a high-pressure cleaning appliance. It comprises an electric motor 11 which is configured as an external rotor motor and has a stator 12 and a rotor 13 which is fitted around the latter and is mounted in a rotationally fixed manner on a motor shaft 14, which is fitted through the stator 12. The swash drive 10 also comprises a swash unit 17 which is surrounded by a cup-like housing 19 and has a swash body 21, which is connected in a rotationally fixed manner to the motor shaft 14, and a swash plate 23. The swash body 21 butts, via a supporting bearing 25 configured as an angular-contact ball bearing, against a supporting plate 28, which is screw-connected to the stator 12. The swash plate 23 is supported on the swash body 21 via a swash-plate bearing 31 configured as an axial ball bearing. In the embodiments which are illustrated in FIGS. 1 to 3, the swash plate is in the form of a planar, annular plate and is inclined in relation to the axis of rotation 33 of the motor shaft 14. Pistons 36 of an axial piston pump, which is known per se and has thus not been illustrated in the drawing, butt against a face 35 of the swash plate 23. The pistons 36 are mounted such that they can be displaced axially, that is to say parallel to the axis of rotation 33, in a cylinder head 37 and are biased in the direction of the swash plate 23 by means of springs which surround the pistons 36 and are known per se, and, for reasons of clarity, have thus not been illustrated in the drawing either.

As is clear from FIG. 2 in particular, the supporting plate 28 has a central opening 39 which has the motor shaft 14 fitted through it and is bounded by a radially oriented inner flange 40 which, via a cranked portion 41, merges into a radially oriented outer flange 42. In relation to the axis of rotation 33, the inner flange 40 is offset with respect to the outer flange 42 in the direction of the swash body 21, and the cranked portion 41 forms, on the swash-body side, that is to say directed toward the swash body 21, a first bearing channel 44 for the supporting bearing 25, so that bearing balls 45 of the supporting bearing 25 can roll on the bearing channels 44.

On the rear side of the supporting plate 28, this rear side being directed away from the first bearing channel 44, the stator 12 butts with surface contact against the supporting plate 28 in the region of the inner flange 40 and is screw-connected to the supporting plate 28 by means of connecting screws 46.

The swash body 21 has a central opening 48 which has the motor shaft 14 fitted through it and is bounded by a radially oriented inner flange 49, which is followed by an annular raised portion 50 which, via a bent-around portion 51, merges into a collar 52 which is directed toward the supporting plate 28. The raised portion 50 extends in the circumferential direction only over part of the swash body 21, its height increasing continuously in the axial direction from a 0 value, over an angle range of 180°, to a maximum value, in order then to drop back to the 0 value again over a further angle range of 180°. The raised portion 50 forms, on the swash-plate side, a bearing surface 54 which is in the form of a circular disc, is inclined obliquely in relation to the axis of rotation 33 and is oriented parallel to the swash plate 23, and in which a first bearing channel 55 of the swash-plate bearing 31 is formed, so that bearing balls 56 of the swash-plate bearing 31 can roll on the bearing channels 55. A corresponding second bearing channel 58 is formed in the swash plate 23 on the swash-body side.

The bent-around portion 51 of the swash body 21 forms, on the supporting-plate side, a second bearing channel 60 for the supporting bearing 25. The bearing balls 45 are supported on their outside, directed away from the axis of rotation 33, by the collar 52 of the swash body 21. On the inside, they are supported on the cranked portion 41.

The housing 19 of the swash drive 10 has a base wall 62 with a central opening 63, and a sleeve-like circumferential wall 64 projects from the base wall 62. The base wall 62 is clamped in between the outer flange 42 of the supporting plate 28 and the stator 12 of the electric motor 11. In the transition region between the base wall 62 and the circumferential wall 64, the housing 19 forms a reception 65 for receiving the supporting plate 28 in a positive manner.

As has already been explained, the electric motor 11 is configured as an external rotor motor, the rotor 13 being fitted around the stator 12 and being connected in a rotationally fixed manner to the motor shaft 14. In the exemplary embodiment which is illustrated in FIG. 1, this motor shaft is supported in a rotatable manner on the one hand on the supporting plate 28, via the swash body 21 and the supporting bearing 25 in the form of an angular-contact ball bearing, and on the other hand on the stator 12, via a ball bearing 67. In addition to performing the function of supporting the swash body 21 in a rotatable manner, the supporting bearing 25 thus also performs the function of supporting the motor shaft 14 in a rotatable manner.

FIG. 3 illustrates a second embodiment of a swash drive according to the invention and is designated 70 overall. This embodiment is largely identical to the swash drive 10 which has been described above. Identical components have thus been designated in FIG. 3 by the same reference numerals as in FIGS. 1 and 2. In respect of these components, in order to avoid repetition, reference is made to the explanations above.

The swash drive 70 differs from the swash drive 10 in that use is made of an electric motor 71 with a motor shaft 72 which is supported only at one end. The bearing mounting at one end of the motor shaft 72 is effected by means of the supporting bearing 25, as has already been described above. The rotor 73 of the electric motor 71 is secured in a rotationally fixed manner on the motor shaft 72 and is fitted around the stator 74 of the electric motor 71. The swash drive 70 is thus distinguished by a particularly straightforward construction.

FIG. 4 illustrates an alternative embodiment of a swash unit which is designated 80 overall and can be used both for the swash drive 10 which is illustrated in FIG. 1 and for the swash drive 70 which is illustrated in FIG. 3. The swash unit 80 is constructed similarly to the swash unit 17 which is illustrated in FIGS. 1, 2 and 3, identical components thus being designated by the same reference numerals as in FIGS. 1, 2 and 3.. In respect of these components, in order to avoid repetition, reference is made to the explanations above.

The swash unit 80 differs from the swash unit 17 in that both the supporting bearing and the swash-plate bearing are configured as angular-contact ball bearings. The swash unit 80 comprises a supporting plate 28 like that which has already been explained above. In addition, it has a swash body 81 and a swash plate 82. The swash body 81 is supported on the supporting plate 28 via a supporting bearing 83 configured as an angular-contact ball bearing, and a swash-plate bearing 84 likewise configured as an angular-contact ball bearing is disposed between the swash plate 82 and the swash body 81.

The swash body 81 forms, on its outer circumference, a collar 86 which is directed toward the supporting plate 28 and, in a radially central region, the swash body 81 is in the form of an annular protrusion 87 which is directed toward the swash plate 82. In the circumferential direction, this protrusion does not have a uniform axial height; rather, the height of the protrusion 87 increases continuously from a minimum height, over an angle range of 180°, to a maximum height, in order to drop back to the minimum height again over a further angle range of 180°. The protrusion 87 has a planar end surface 88 which is inclined in relation to the axis of rotation 33 in a manner corresponding to the swash plate 82. The protrusion 87 encloses a central well-like depression with a base wall 89 which has a central opening 90 and is oriented parallel to the supporting plate 28.

On the outside, the end surface 88 is followed, in a transition region between the protrusion 87 and the collar 86, by a bearing channel 91 for bearing balls 92 of the swash-plate bearing 84. The bearing balls 92 are thus supported by the protrusion 87 on the inside.

Offset radially outward with respect to the bearing channel 91, the bearing body 81 forms, on the supporting-plate side, a bearing channel 93 for bearing balls 94 of the supporting bearing 83. The bearing channel 44 of the supporting plate 28 corresponds with the bearing channel 93 of the swash body 81. The bearing balls 94 are supported by the collar 86 on the outside.

The swash plate 82 is configured as a planar annular plate which is oriented obliquely in relation to the axis of rotation 33 and merges, via a bent-around portion 96, into a collar 97 which is directed toward the swash body 81, and the bent-around portion 96 forms, on the swash-body side, a bearing channel 98 which corresponds with the bearing channel 91 of the swash body 81.

Both for the swash unit 17 and for the swash unit 80, the supporting plate 28 forms an alignment aid for assembling the swash drive, since the supporting bearings 25 and 83, respectively, can be positioned on the cranked portion 41 of the supporting plate 28 without any further assembly aid.

For the swash unit 80, the swash body 81 forms a further alignment aid for assembly purposes, since the swash-plate bearing 84 can be positioned on the protrusion 87 without any further assembly aid.

The spacing between the base of the bearing channels 55 and 91 of the swash-plate bearings 31 and 84, respectively, and the base of the bearing channel 60 or 93 of the supporting bearing 25 or 83, respectively, is less than the diameter of the bearing balls 45 and 94 of the supporting bearings 25 and 83, respectively. This allows the swash units 17 and 80 to be subjected to particularly high loading. This makes it possible, in particular, to orient the swash plates 23 and 82 at an angle of inclination of more than 140 in relation to the axis of rotation 33.