EP2024635A1

EP2024635A1 - Hydrostatic piston machine and thrust ring for a brake device of the former

Info

Publication number: EP2024635A1
Application number: EP07725380A
Authority: EP
Inventors: Rainer Stölzer
Original assignee: Brueninghaus Hydromatik GmbH
Current assignee: Brueninghaus Hydromatik GmbH
Priority date: 2006-06-02
Filing date: 2007-05-18
Publication date: 2009-02-18
Also published as: KR20080059385A; WO2007140869A1; JP2009531620A; JP4988819B2; CN101326362B; CN101326362A; DE102006025969A1

Abstract

The invention relates to a hydrostatic piston machine having a housing (2), a cylinder drum (3) which is mounted rotatably in the latter, a multiple disc brake (16) and a thrust ring (21) for this purpose. The cylinder drum (3) can be braked in the housing (2) by the multiple disc brake (16), the multiple disc brake (16) comprising at least one first brake disc (19) which is connected fixedly in terms of rotation to the cylinder drum (3) and at least one second brake disc (20) which is connected fixedly in terms of rotation to the housing (2). The brake discs (19, 20) can be pressed onto one another by the thrust ring (21), the thrust ring (21) being a plastic ring and having at least one region (35, 36) which is elastic in the radial direction and on which a sealing element is provided.

Description

Hydrostatic piston engine and pressure ring for a braking device of the same

The invention relates to a pressure ring for a brake device of a hydrostatic piston engine and a hydrostatic piston engine.

It is known in hydrostatic piston machines which have a cylinder drum which is rotatably mounted in a housing to be able to decelerate the cylinder drum relative to the housing can. For this purpose, a braking device in the form of a multi-disc brake is arranged between the cylinder drum and the housing. The multi-disc brake is usually designed so that brake plates are pressed against one another with the aid of compression springs. For safety, therefore, the cylinder drum is only rotatable when the pressing force of the brake plates is reduced by generating a pressure. To transmit the pressing force, a pressure ring is provided, which is loaded by springs and can be acted upon in the opposite direction by a hydraulic force.

Such a pressure ring and such a hydrostatic piston machine are known from DE 42 14 397 A1. Usually, the pressure ring is made of a simple steel. For sealing the pressure ring relative to the housing grooves are provided on the outer periphery of the pressure ring, in which O-rings are arranged. These O-rings are provided in the axial direction on both sides of a formed on the circumference of the pressure ring stage. The step forms on the pressure ring a pointing in the axial direction, pressurizable surface. On this surface, the hydraulic force is generated, which serves to release the braking device.

A disadvantage of the known pressure ring and the known hydrostatic piston engine is that steel is used as the material for the pressure ring. This requires expensive metalworking processes to handle the generate required geometries with the necessary accuracy. In particular, the manufacturing tolerances with respect to the circumference of the two diameters forming the step are necessary in order to achieve a reliable seal on both sides of the surface to be pressure-blown. Such tightness is required to prevent a pressure drop on the pressure surface, which would lead to an undesirable braking effect.

The invention is therefore based on the object to provide a pressure ring and a hydrostatic piston engine with a braking device in which or in a simple manner a good and reliable sealing effect can be achieved and the or is inexpensive to produce.

The object is achieved by the pressure ring according to the invention according to claim 1 and the hydrostatic piston machine according to the invention with the features of claim 12.

The pressure ring according to the invention for a brake device of a hydrostatic piston machine has a surface to be impacted by pressure. The pressure ring itself is made of plastic and has at least one elastic region in the radial direction, wherein a sealing element is provided on the elastic region. In contrast to the expensive and expensive machining process of a steel ring, the pressure ring designed according to the invention as a plastic ring makes it possible to form the required geometries in a simple manner. In particular, at least one elastic region can thus be formed, which presses the sealing element in the elastic region against the housing of the hydrostatic piston machine according to the invention. By providing this elastic region, which reliably holds the sealing elements in contact with the housing, the actual outer diameter of the pressure ring can be produced on both sides of the pressure-bearable surface with a larger tolerance. This facilitates the production of the production tools for producing the pressure ring and thus significantly reduces the manufacturing costs without sacrificing durability.

In the dependent claims advantageous developments of the pressure ring according to the invention are carried out.

In particular, it is advantageous to be oriented at an opposite to the pressurizable surface

End face of the pressure ring to provide at least one recess in which at least one elastic pressure element is arranged. The elastic pressure element serves to act on the braking device with an axial force, so that in case of failure of the hydraulic system and thus a decrease in the opening pressure, the braking device engages and brakes the hydrostatic piston engine. In this case, the pressure ring is extended in the region of the recesses for receiving the elastic pressure elements in the axial direction beyond its end face. This ensures improved guidance of the elastic pressure elements, so that tilting, for example, formed as coil springs pressure elements is prevented.

The at least one elastic region in which the sealing element is arranged is preferably introduced in the axial direction into a first end face and / or a second end face of the pressure ring. If, for example, a two-part injection mold is used for producing the pressure ring, then this recess can be introduced in the form of a circumferential groove in a simple manner already during injection molding.

According to a preferred first embodiment, a sealing ring is arranged on the outer circumference of the pressure ring in each case in the region of these circumferential grooves. In the pressure ring this is in the axial direction corresponding to the circumferential grooves for generating the elasticity each formed a receiving groove for receiving, for example, an O-ring.

It is particularly preferred to form the pressure ring with a first ring element and a second ring element. On the one hand, such a two-part design facilitates the production, since the individual injection molds are even further simplified compared to a one-piece design. In this case, preferably, a ring element on both the recesses for receiving the elastic pressure elements and the pressurizable surface. The pressurizable surface is defined by a radially outer portion of an opposite end face of the first end face of the first

Formed ring element. At this end face lies in a radially inner region of the second ring element with its end face.

The first ring element and the second ring element are preferably connectable to each other to the sealing ring. The connection can be done either by positive engagement or by material connection. If the connection is designed as a positive connection, then the first ring element is connected to the second, for example, by a latching connection

Ring element connected. As a material-locking connection, it makes sense to first bring the two ring elements in abutment with each other and then to connect them together, for example by ultrasonic welding. The thus formed pressure ring can then be used in a simple manner during assembly of the hydrostatic piston engine.

In the two-part embodiment of the pressure ring, it is particularly advantageous that in the at least one elastic region which is formed on the first ring element or on the second ring element, a plastic lip is arranged as a radially acting sealing portion. For forming the elastic region, which allows a slight change of the outer circumference of the pressure ring and thus its radial extent, it is particularly advantageous to introduce in each case a circumferential groove in the axial direction of the end faces of the ring elements both in the first ring member and in the second ring member. The circumferential groove is thereby introduced from the mutually facing end faces of the first ring member and the second ring member. This has the advantage that due to the intervening to open the

Braking pressure surface increases the pressure in the formed circumferential grooves and thus increases the force with which the sealing lips are pressed against the housing. If, in contrast, the region is pressure-free, as is the case when the hydrostatic piston engine is not in operation, then the sealing lips are not loaded with a force in the radial direction.

In order to allow for the mounting of the first ring member and the second ring member to a pressure ring in a simple manner a centering, preferably the first ring member and the second ring member is formed in each case in a step geometry. The mutually facing step geometries correspond to one another in such a way that, for example, the first ring element is centered on the step formed on the second ring element.

Preferred embodiments of the pressure ring according to the invention and the hydrostatic piston machine according to the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1 is a sectional view of a hydrostatic piston engine;

2 shows an embodiment of a braking device with a first pressure ring according to the invention; 3 shows an embodiment of a braking device with a second pressure ring according to the invention;

4 shows a further view of the first pressure ring according to the invention from FIG. 2; and

5 shows a further view of the second pressure ring according to the invention according to FIG. 3.

Before discussing the structural design of the pressure ring according to the invention in detail, a hydrostatic piston engine according to the invention will first be explained in its essential components. In Fig. 1, a hydrostatic piston machine 1 according to the invention is shown. The hydrostatic piston machine 1 has a rotatably mounted cylindrical drum 3. The housing 2 is closed by a connection plate 4, in which connections for connecting the hydrostatic piston engine 1 are formed in a conventional manner to a hydraulic circuit.

In the housing 2 and the connection plate 4, a first bearing 5 and a second bearing 6 are arranged, in which a drive shaft 7 is rotatably mounted. The cylinder drum 3 is rotatably connected to the drive shaft 7. For generating a delivery volume when the hydrostatic piston engine 1 is used as a pump, a plurality of cylinder bores 9 are formed in the cylinder barrel 3. The cylinder bores 9 extend in the axial direction. In each cylinder bore 9, a piston 10 is arranged longitudinally displaceable. The piston 10 is supported via a sliding block 11 on a swash plate 12.

The swash plate 12 is made adjustable in the illustrated embodiment, for which an adjusting device 13 acts on the swash plate 12. To actuate the adjusting device 13 is an actuating piston 14 arranged in a cavity of the housing 7. On one side of the actuating piston 14 can be acted upon in the cavity with a hydraulic pressure, for which purpose via a control pressure line 15 pressure medium is supplied. Depending on the position of the adjusting piston 14, the inclination of the swash plate 12 changes to the axis of rotation of the cylindrical drum 3, so that the stroke of the piston 10 executed during one revolution of the cylinder drum 3 can be adjusted.

In order to be able to brake a rotation of the cylinder drum 3, a braking device 16 is provided between the cylinder drum 3 and the housing 2. For this purpose, a plurality of grooves 17 extending in the axial direction are formed on the outer circumference of the cylindrical drum 3.

Accordingly, a plurality of grooves 18 are formed in the housing 2 in a position corresponding to the grooves 17 in the axial direction. The braking device 16 further comprises first brake plates 19 and second brake plates 20. The number of

Brake plates 19, 20 is to be selected depending on the expected braking power. The brake plates 19, 20 are substantially annular. In this case, the outer diameter of the first brake plates 19 is greater than the inner diameter of the second brake plates 20.

On the inner circumference of the first brake plates 19, a toothing is formed through which a rotationally fixed connection between the first brake plates 19 and the cylinder drum 3 is generated. The toothing of the first brake plates 19 engages in the grooves 17 of the cylinder drum 3 for this purpose.

In a corresponding manner, a toothing is also formed on the outer periphery of the second brake plates 20, which cooperates with the grooves 18 in the housing 2. In this way, the first brake plates 19 are rotatably connected to the cylinder drum 3, the second brake plates 20 against rotation with the housing 2 connected. In the axial direction, the brake discs in the grooves 17, 18th displaced. The brake plates 19 and 20 are each arranged alternately, wherein a second brake plate 20 is provided more than first brake plates 19. The plate assembly consisting alternately of the first and second brake plates 19, 20 is thus completed on both sides by a second brake plate 20, which relatively is arranged rotationally fixed to the housing 2.

As long as no force is exerted on the disk set in the axial direction, the first

Brake plates 19 rotate between the second brake plates 20 almost free of force, so that a rotation of the cylinder barrel 3 in the housing 2 is possible. In order to increase the surface pressure between the first brake plates 19 and the second brake plates 20 and so on

To produce braking effect, a pressure ring 21 is provided. The pressure ring 21 can exert an axial force on the disk set. In order to press the first brake plates 19 and the second brake plates 20 toward one another, a pressure plate 22 for supporting the force of the pressure ring 21 is formed on the side of the plate packet opposite the pressure ring 21, for example. Instead of the pressure plate 22, only a radial step can be provided in the housing 2.

For better clarity, the pressure ring 21 is shown in Fig. 1 in a simplified embodiment. The exact structural design of the pressure ring 21 will be explained below with reference to FIGS. 2-5.

On the pressure ring 21, a pressurizable surface 23 is formed by a radial step on the outer periphery. Corresponding to the pressurizable surface 23, a radial step is provided in the housing 2, so that a control pressure chamber 24 is formed between the pressure ring 21 and the housing 2. If the control pressure chamber 24 is depressed with pressure medium, acts on the pressurizable surface 23 of the pressure ring 21 a axial force which acts on the pressure ring 21 in Fig. 1 to the left. Upon pressing the control pressure chamber 24 thus a force is exerted on the pressure chamber 21, which relieves the disk set. In this case, a free rotation of the cylinder barrel 3 in the housing 2 is possible.

In order to be able to generate a braking action by the braking device 16, a plurality of elastic pressure elements are preferably provided. In the dargstellten embodiment, the elastic pressure elements are formed as coil springs 25.

Opposite to the pressurizable surface 23, a first end face 27 is formed on the pressure ring 21. From the side of the first end face 27 a plurality of recesses 26 are formed in the pressure ring 21 distributed over the circumference. The coil springs 25 are inserted into these recesses 26 and are supported in the opposite direction, for example, on the connection plate 4. By the coil springs 25 thus an axial spring force is exerted on the pressure ring 21, which is supported on the disk set consisting of the first brake plates 19 and the second brake plates 20. If the control pressure chamber 24 is not acted upon by a control pressure, is thus by the

Spiral springs 25 generates a braking force in which the first and second brake plates 19, 20 are pressed against each other. To generate the braking force and a second pressurizable surface may be provided in a second control pressure chamber.

In order to prevent unnecessary pressure loss from the control pressure chamber 24, a first sealing element 28 and a second sealing element 29 are provided on the pressure ring 21. In a further recess of the pressure ring 21, a sleeve 30 is arranged, which together with a dowel pin 31 prevents undesired co-rotation of the pressure ring 21 in the housing 2. The dowel pin 31 is fixed in a bore 32 of the connection plate 4 for this purpose. 2, an enlarged view of a pressure ring 21 is shown according to a first preferred embodiment. The pressure ring 21 is designed graduated at its outer periphery, wherein the pressure-loadable surface 23 is formed at the transition between the two different diameters. Opposite oriented to the pressurizable surface 23, a first end face 21 is formed. At the axially opposite end of

Pressure ring 21 is a second end face 34 is formed. At the second end face 34, a projection 34 'is formed in the illustrated embodiment, which exerts on the foremost of the second brake plates 20 an axial force for generating the braking effect.

As has already been described, preferably a plurality of recesses 26 are introduced into the pressure ring 21 from the side of the first end face 27. In order to improve the guidance of the coil springs 25 arranged there, an extension 33 is formed on the pressure ring 21 beyond the first end face 27. This extension 33 is formed either individually for each recess 26 or together as a neck on the pressure ring 21 circulating.

Axially on both sides of the pressurizable surface 23 sealing areas are formed on the pressure ring 21. To improve the sealing effect, a first elastic region 35 is arranged from the pressurizable surface 23 in the direction of the first end face 27. From the pressurizable surface 23 to the second end face 34 toward a second elastic region 36 is formed. In the first elastic region 35, the first sealing element 28 is arranged. Accordingly, in the second elastic region 36, the second sealing element 29 is formed. In order to form a first elastic region 35 in the pressure ring 21 made of plastic, a circumferential groove 27 is inserted axially into the pressure ring 21 from the first end face 27. Depending on the depth of the circumferential groove 37, the elasticity can be adjusted together with a suitable choice of material in the first elastic region 35. For receiving the sealing element 28 in the first elastic region 35, a radial receiving groove is introduced into the pressure ring 21 from the outer circumference of the pressure ring 21. A further radial receiving groove is introduced into the second elastic region 36 in the pressure ring 21, wherein the second sealing element 29 is arranged in this second receiving groove. The first sealing element 28 and the second sealing element 29 are designed, for example, as O-rings, wherein a supporting element, for example in the form of a stabilizing ring, can additionally be arranged in the respective receiving groove.

The second elastic portion 36 is formed corresponding to the first elastic portion 36 by inserting a second circumferential groove 38 in the pressure ring 21. The second circumferential groove 38 is introduced into the pressure ring 21 from the second end face 34 in this case. It is again by selecting the

Material of the pressure ring 21 and by the depth and the radial arrangement and the second extension encircling groove 38, the elasticity of the second elastic portion 36 adjustable. In addition to the pressure ring 21, a mounting ring 40 is provided on the side of the first end face 27.

3, a second embodiment of a pressure ring 21 according to the invention is shown. In this case, the pressure ring 21 'comprises a first ring element 41 and a second ring element 42. The features corresponding to the pressure ring 21 of FIG. 2 are provided with identical reference numerals. On a complete renewed Description is omitted to avoid repetition.

In the first ring member 41, the recesses 26 are arranged for receiving the coil springs 25. Opposed to the first end face 27, an end face 46 is formed on the first ring element 41. The radially outer region of the first end face 46 forms the pressurizable surface 23. The second ring member 42 is with respect to its outer radial

Dimension smaller than the first ring member 41. The second ring member 42 is located with its opposite to the second end face 34 of the pressure ring 21 'oriented end face 47 into contact with a radially inner region of the end face 46 of the first ring member 41. The inner diameter of the two ring elements 41st , 42 corresponds to each other. The end face 46 of the first ring element 41 and the end face 47 of the second ring element 42 each have a step. The position of the step in the first ring member 41 and in the second ring member 42 corresponds to each other, so that a centering 45 of the ring members 41, 42 is formed by the step.

As in the case of the first exemplary embodiment of FIG. 2, a first elastic region 35 'and a second elastic region 36' are also formed on the pressure ring 21 '. In the second embodiment, the first elastic portion 35 'in the first ring member 41 and the second elastic portion 36' in the second

Ring element 42 is arranged. In order to produce the elastic regions 35 'and 36', in each case a first and a second circumferential groove 37 'or 38' is again provided. The first circumferential groove 37 'is inserted into the first ring member 41 from its front side 46 ago. By the first circumferential groove 37 ', which is introduced from the end face 46 ago in the first ring member 41, a first plastic lip 43 is formed as a sealing element on the outer peripheral edge. The first plastic lip 43 is connected to the first ring member 41 connected in an elastic manner. The sealing effect is generated in the pressure ring 21 'according to the second embodiment by this first plastic lip 43, which is in contact with the housing 2 when the pressure ring 21' is mounted. In a corresponding manner, the second circumferential groove 38 'is introduced from the end face 47 into the second ring element 42. As a result, the second elastic region 36 'is formed on the outer peripheral edge of the second ring element 42 and a second plastic lip 44 as a sealing element.

Corresponding to the first plastic lip 43, the sealing action between the second ring element 42 and the housing 2 is likewise effected by the second plastic lip 44. The second plastic lip 44 is for this purpose in the assembled state of the sealing ring 21 'in contact with the housing 2 of the hydrostatic piston machine. 1

Since the open sides of the first groove 37 'and the second groove 38' are facing the pressurizable surface 23, upon pressing the control pressure chamber 24, the first circumferential groove 37 'and the second circumferential groove 38' is depressed with pressure medium. This leads to an expansion of the outer diameter of the first plastic lip 43 and the second plastic lip 44, whereby the sealing effect of the two plastic lips 43, 44 and thus the sealing of the control pressure chamber 24 improves.

FIGS. 4 and 5 once again show exemplary embodiments of the pressure ring 21 and 21 'according to the invention. In particular, it is shown in FIG. 5 that the first ring element 41 can be connected to the second ring element 42 via a latching connection. Such a positive connection has the advantage that without further process step, the two ring elements 41, 42 can be connected to each other in a simple manner by juxtaposing. The latching connection is in the illustrated embodiment by a sloping edge on the outer periphery in the region of the centering 45 and a corresponding recess on the other ring element educated. In addition, it can be seen in FIG. 5 that the second plastic lip 44 has an overflow channel 48 in the region of its contact with the pressurizable surface 23, so that an inner volume of the second circumferential groove 38 'is in fluid contact with the control pressure chamber 24. This leads to the already described increase in the sealing effect if the control pressure chamber 24 is acted upon by a control pressure.

In the embodiments of FIGS. 3 and 5, the second end face 34 is flat.

In addition to the positive connection or as an alternative to this, the first ring element 41 may also be materially connected to the second ring element 42. For example, the adjoining regions of the end faces 46, 47 of the first ring element 41 and of the second ring element 42 can be materially connected to one another in the region of their inner circumference by ultrasonic welding.

In the described embodiments, the braking force is generated by the coil springs 25. A loosening of the braking device 16 is effected by generating a setting pressure in the control pressure chamber 24. Conversely, the braking device by the coil springs in the released position and the braking force by applying the control pressure chamber 24 done. The arrangement of the pressurizable surface and the elastic elements in the piston engine is then to reverse accordingly.

The invention is not limited to the illustrated embodiments. In particular, it is possible to combine individual features of the embodiments in any way with each other.

Claims

claims

1. pressure ring for a brake device of a hydrostatic piston machine, wherein the pressure ring (21) has at least one pressurizable surface (23), characterized in that the pressure ring (21,21 ') is made of plastic and at least one in the radial direction elastic region ( 35, 36, 35 ', 36') on which a sealing element (28, 29; 43, 44) is provided.

2. Pressure ring according to claim 1, characterized in that in an opposite to the pressurizable surface (23) oriented first end face (27) at least one recess (26) for receiving an elastic

Pressure element (25) is introduced and that the pressure ring (21,21 ') in the region of at least one

Recess is extended in the axial direction beyond the first end face (27) addition.

3. Pressure ring according to claims 1 or 2, characterized in that for forming the at least one elastic region (35, 36, 35 ', 36') from the side of the first

End face (27) and / or from the side of a second, facing in the opposite direction end face (34) has a circumferential groove (37,38) is introduced.

4. Pressure ring according to claim 3, characterized in that in the region of the circumferential groove (37,38) on the outer periphery of the pressure ring (21,21 ') inserted, acting in the radial direction sealing element (28,29) is arranged.

5. Pressure ring according to claim 1 or 2, characterized in that the pressure ring comprises a first ring element (41) and a second ring element (42).

6. Pressure ring according to claim 5, characterized in that the first ring element (41) has at least one recess (26) for receiving the at least one elastic

Pressure element (25) and the pressurizable surface (23), wherein the pressurizable surface (23) by a radially outer region of an opposite to the first end face (27) oriented end face (46) of the first ring member (41) is formed.

7. Pressure ring according to claim 5 or 6, characterized in that the first ring element (41) and the second ring element (42) by a positive connection to the pressure ring (21 ') are connectable.

8. Pressure ring according to claim 5 or 6, characterized in that the first ring element (41) and the second ring element (42) are connected by a material-locking connection to the pressure ring (21 ').

9. Pressure ring according to one of claims 5 to 8, characterized in that on the first ring element (41) and / or on the second ring element (42) a radially acting sealing portion by a plastic lip (43,44) is formed.

10. Pressure ring according to claim 9, characterized in that for forming the plastic lip (43,44) in the first ring element (41) from its second ring element (42) facing end face (46) from a circumferential groove (37 ') is introduced and / or that for forming the plastic lip (43,44) in the second ring member (42) from its the first ring member (41) facing the end face (47) from a groove is introduced.

11. Pressure ring according to one of claims 5 to 10, characterized in that the first ring element (41) and the second ring element (42) on their mutually facing end faces (46,47) have corresponding step geometries, the two ring elements (41,42 ) center relative to each other.

12. Hydrostatic piston engine with a housing (2) and a rotatably mounted therein cylindrical drum (3), wherein the cylinder drum (3) by means of a multi-disc brake (16) in the housing (2) can be braked, wherein the multi-disc brake (16) at least one rotationally fixed comprises first brake disks (19) connected to the cylinder drum (3) and at least one second brake disks (20) connected to the housing (2) in a rotatable manner which can be pressed against one another by a pressure ring (21, 21 '), characterized in that the pressure ring (21,21 ') is a plastic ring according to one of claims 1 to 12.