EP2496867A1

EP2496867A1 - Valve arrangement

Info

Publication number: EP2496867A1
Application number: EP10754885A
Authority: EP
Inventors: Christian Spielvogel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-11-05
Filing date: 2010-09-15
Publication date: 2012-09-12
Also published as: CN102667273A; CN102667273B; DE102009052076A1; WO2011054413A1; US20120273067A1

Abstract

A hydraulic valve arrangement is proposed, in particular a regulating-valve arrangement of a variable displacement pump, wherein a valve piston (8, 60) of a valve is prestressed into a basic position via a spring arrangement. Said spring arrangement is supported on an expander (50).

Description

description

valve assembly

The present invention relates to a valve arrangement, in particular a control valve of a variable displacement pump according to the preamble of claim 1.

From DE 101 36 416 A1 a generic control valve assembly is known. This has a valve housing, in which a pressure control valve and a flow control valve are integrated. A control piston of the control valves is biased in each case by means of a control spring in one direction. In the known solution, a spring housing is attached to the front side of the valve housing, in which the respective control spring is arranged, which acts on a spring plate on the control piston. This control spring in turn is supported on a support disk, which is adjustable by means of an adjusting screw in the axial direction, so that the control spring preload can be adjusted via the adjusting screw.

Such control valves for variable displacement pumps are usually set to values desired by the customer. This setting is preferably made only once at the pump manufacturer before delivery of the variable. For this purpose, the adjustment pumps are set on test benches during pump production by a test person and secured against subsequent, accidental change the setting. This backup takes place, for example, in the generic control valves via a lock nut, via which the adjusting screw is clamped to the spring housing. To seal the spring chamber, O-rings are still required in the known solution, which seal the overlap area between the spring housing and the valve housing and the other between the adjusting screw and the spring housing, so that the spring spring receiving the spring chamber to the outside Reliably completed.

A disadvantage of this solution is that a plurality of components for adjusting and supporting the control spring and a plurality of seals must be provided for sealing the spring chamber. In contrast, the invention has for its object to provide a simply constructed valve assembly.

This object is achieved by a valve arrangement having the features of patent claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

According to the invention, the hydraulic valve arrangement is designed with a valve housing in which a valve piston receiving a valve bore is formed. This valve piston is biased by a spring which is supported on an at least once axially adjustable spring seat. According to the invention, this spring seat is designed instead of the initially described, very elaborately performed screw adjustment as a radially expandable expansion sleeve, which is non-positively inserted into the valve bore and this closes. Such radially expandable expansion sleeves are also known by the term "expander" and are also used in hydraulics. For example, DE 199 33 371 A1 describes bracing an expansion sleeve by means of a throttle body, which is designed with a constriction along which Tear throttle body during clamping and then releases the throttle cross-section.

In US 4,091,841 it is described to close a pressure medium flow path by means of an expander.

However, the use of these expander for supporting springs of a hydraulic valve arrangement is in the prior art without any model.

By using such expansion sleeves can be dispensed with the complex thread adjustment according to the prior art; Furthermore, the number of sealing surfaces compared to this prior art is substantially reduced, since this expansion sleeve can be used directly in a valve bore or an adjoining spring chamber, without the need for an additional spring housing for receiving the above-described actuator. Accordingly, the number of components and the sealing surfaces compared to the solution described above can be significantly reduced, so that both the assembly and the production is simplified. To adjust the indirectly or directly applied to the spring expansion sleeve is inserted into the valve bore or the spring chamber until the desired setting is reached and then expanded radially, so that it is tightly clamped to the valve bore and the spring chamber. During this radial expansion, the axial position of the expansion sleeve does not change, so that the desired setting value is reliably maintained.

In a preferred embodiment of the invention, the expansion sleeve is designed with a cone bolt, for example, via a tie rod attached to the. radial expansion of the expansion sleeve is actuated. This pull rod is preferably provided with a predetermined breaking point, so that it can be released after the expansion of the expansion sleeve from the cone bolt.

According to the invention, it is preferred if the spring-side end face of the expansion sleeve protrudes beyond the cone bolt at least around the assembly path for expansion in the axial direction toward the spring, so that the cone bolt does not come into operative connection with the spring either in the unexpanded basic position of the expansion sleeve or in the expansion position can.

This can be made particularly simple by the spring side of the expansion sleeve adjoins a spacer, that this spring-side end surface forms and its axial length is determined so that the cone bolt in the loose inserted into the expansion sleeve state does not project beyond the spacer in the axial direction.

This spacer can be made in one piece with the expansion sleeve or as a separate component.

In one embodiment of the invention, a support disk is arranged between the spacer and the spring, which serves as a support for the spring. This support disk can in turn be designed as a separate component or else integrally with the spacer. In one embodiment, an inner bore of the expansion sleeve is executed in opposite directions conical to the cone bolt. The inner diameter of the spacer is accordingly made larger than the largest diameter of the cone bolt or the expansion sleeve.

To further improve the positional fixation of the expansion sleeve, circumferential grooves can be formed on its outer circumference, which leads to a "hooking" with the peripheral wall of the valve bore and thus improves the seat.

In a preferred embodiment of the invention, the control springs of a flow control valve and a pressure control valve of a pump regulator are supported in the manner described above via an expansion sleeve.

A preferred embodiment will be explained in more detail below with reference to a single figure, which shows a longitudinal section through a control valve assembly 1 of a pump controller. The basic structure of this control valve arrangement 1 is described in detail in the prior art described in the introduction according to DE 101 36 416 A1. The schematic structure of the pump controller is further explained in the out of the Bosch Rexroth AG out data sheet RD 92 711 / 10.07, so that in the following only the essential components for understanding the invention are described and incidentally for the sake of simplicity to the aforementioned state of Technology is referenced.

The control valve assembly 1 has a valve housing 2, in which a flow control valve 4 and a pressure control valve 6 are accommodated. The pressure control valve 6 causes a constant pressure in a hydraulic system within the control range of the pump. By means of the flow control valve 4, the flow rate of the pump can be adjusted via a differential pressure at the consumer so that the pump promotes only the pressure medium actually required by the consumer.

On the valve housing there are a pressure connection P leading to the pump pressure, a working connection A, a tank connection T and an LS connection indicated only in the figure. X is provided. Said working port A is in fluid communication with a pressure chamber of an actuating cylinder, via which, as explained in the data sheet RE 92 711, a pivot angle of an adjustable axial piston pump is adjustable. A swash plate of this axial piston pump is swung out via a spring mechanism and can be pivoted back by the pressure in the pressure chamber of the actuating cylinder. At the LS port X is the highest load pressure of all consumers of the supplied via the pump with pressure medium system, which is tapped for example via a shuttle valve cascade from the consumer.

The pressure control valve 6 has a pressure control piston 8 which is guided in a valve bore 10 and is biased via a pressure control spring assembly 12 with two coaxially arranged springs in the illustrated basic position in which it rests against a valve 10 inserted into the valve plug 10. In the valve bore 10 leads to the pressure port P leading, designed as an inclined bore pressure channel 16, which extends beyond the valve bore 10 also up to a valve bore 18 of the flow control valve 4. The pressure regulating piston 8 is designed with a control collar 20, a guide collar 22 arranged adjacently thereto and two end collars 24 and 26. The left in the figure left end 26 is in the Gruhdposition on the screw 14 and limited with this one not visible in the figure control chamber which acts on a designed as an angular bore control bore 28 with the pressure in the annular space between the end collar 26 and the control collar 20 is. This control pressure corresponds to the pump pressure.

In the hydraulically connected to the actuating cylinder working port A also runs as a blind hole working channel 30 which intersects the valve bore 10 and immersed in the illustrated basic position of the control collar 20 with its right end portion, so that the pressure medium connection between the pressure port P and the working port A is locked.

In the figure below the valve bore 10 extends parallel to this a longitudinal channel 32, which opens into a tank channel 34 leading to the tank T right. In this longitudinal channel 32, a nozzle body 36 with two radial nozzles 38, 40 is used in the transverse direction, via which the working channel 30 is connected to the tank channel 34. Between these two nozzles 38, 40 opens an intermediate channel 39 which connects the two valve holes 10, 18 with each other and in the illustrated basic position a left end portion of the guide collar 22 dives, so that in this basic position, the pressure medium connection between the working channel 30 and Connecting channel 39 is opened by the cam between the two coils 20, 22.

The right in the figure end collar 24 abuts against a spring plate 42 to which the pressure control spring assembly 12 engages. This is supported on a support plate 44, which in turn rests on a spacer 58 on an expander 46 which is non-positively inserted into a coaxial with the valve bore 10 formed spring chamber 48. The axial position of the expander 46 and the support plate 44 within the spring chamber 48 determines the bias of the pressure control spring assembly 12 and thus the

Control pressure of the pressure control valve 6. The expander 46 has a radially expandable expansion sleeve 50, with a conical, tapering towards the right cone bore 52 which is clamped with a cone bolt 54. This cone bolt 54 can be moved to the right via a suitable device, for example via a tear-off pin 88 or other device in the axial direction to expand the expansion sleeve 50 in the radial direction and to clamp force-locking and sealing with the outer periphery of the spring chamber 48. The geometry of the expansion sleeve 50 is chosen so that this strain is accompanied by a deformation of the material, which supports the non-positive connection. On the outer circumference of the expansion sleeve 50, one or more circumferential grooves 56 are provided in the illustrated embodiment. As stated at the outset, these circumferential projections 56 serve to improve the fit of the expansion sleeve 50 on the surrounding peripheral wall. The number and shape of the

Circumferential grooves 56 is dependent on the material pairing (expansion sleeve 50, valve housing 2). In principle, it is also possible to dispense with such a circumferential groove.

Since - as shown in the figure - the conical bolt 54 in the unstressed state and also in the clamped state (see figure) protrudes to the left over the expansion sleeve 50, is dependent on this assembly path (axial distance between unverspann- ter position and strained position of the cone pin 54) a spacer sleeve 58 is provided whose axial length is greater than the aforementioned path, so that the cone bolt 54 can be moved without collision with the support plate 44. For assembly, the unit consisting of support plate 44, spacer sleeve 58, expansion sleeve 50 and cone bolt 54 is inserted into the spring chamber 48 and adjusted so far until the desired settings are reached. This adjustment is preferably carried out hydraulically, ie during operation of the valve arrangement, the expander 46 is inserted into the spring chamber 48 until the pressure cutoff has reached the desired pressure value, for example 250 bar. The thereby reached axial position of the expander 46 is then secured by a dashed lines indicated counter-holder 90, which abuts the end face of the expansion sleeve 50.

Following this, the cone bolt 54 is moved to the radial expansion of the expansion sleeve 50 by means of Abreißstifts 88 from its unillustrated position to the right until the expansion sleeve 50 frictionally abuts the peripheral wall of the spring chamber 48, via the spacer sleeve 58, the support plate 44 always at a distance is held to the cone bolt 54. After clamping this expander 46, the spring chamber 48 is shut off pressure-tight and fixed the bias of the pressure control spring assembly 12 and can not be changed accidentally. The attached via a predetermined breaking point 89 to the cone bolt 54 Abreißstift 88 tears off when a certain tensile force is exceeded, so that it is then separated from the cone bolt 54.

The flow control valve 4 shown in the figure above has a control piston 60 which is displaceable in the valve bore 18 and is biased in the normal position according to the figure via a control spring assembly 62 against a further screw plug 64. The control piston 60 has a control collar 66, a guide collar 68 and two Endbunde 70, 72. The latter Endbund 72 immersed in a spring chamber 74 for the control spring assembly 62, the other end collar 70 is in the home position on the screw plug 64 and limited with her a control chamber which is acted upon by another as an angular bore control bore 76 with the pressure in an annular space between the control collar 66 and the end collar 70. In this annular space of the pressure channel 16 opens, so that in the left control chamber of the flow control valve 4, the pump pressure is applied. The control collar 66 is designed so that it shuts off the pressure medium connection of said control space and thus of the pressure channel 16 to the intermediate channel 39 in the basic position. In the illustrated basic position, the pressure medium connection between the intermediate channel 39 and the tank channel 34 is controlled via the control groove between the control collar 66 and the guide collar 68, so that the working port A communicates via the working channel 30, the intermediate channel 39 and the tank channel 34 with the Tank connection T is connected and thus the pressure chamber of the adjusting cylinder for adjusting the pivot angle is acted upon with tank pressure (pump swung).

The control spring assembly 62 engages via a spring plate 77 on the end collar 72 of the control piston 60 and is supported on a support plate 78 whose axial position is also set via an expander 80. The structure of the expander 80 corresponds to that of the expander 46 of the pressure control valve 6. Accordingly, a Spreizhülse 84 is clamped by a conical bolt 82 with the peripheral wall of the spring chamber 62, again a spacer sleeve 86 is provided to the required mounting stroke of the taper bolt 82 without colliding with the Support disc 78 to allow. In the case of the expander 80, the abovementioned tear-off pin 88 is still visible, which projects out of the valve housing 2 in the axial direction - this can be completely removed.

In the region of the spring chamber 74 between the expander 80 and the end collar 72, the highest load pressure of the driven consumer acts, which is tapped off via the LS connection X. Accordingly, the control piston 60 of the flow control valve 4 is acted upon on the one hand by the pump pressure and on the other hand by the load pressure and by the force of the control spring arrangement 62, so that in the control position the pump pressure is adjusted to a value which lies above the highest load pressure by the pressure equivalent of the control spring arrangement 62. In this control position, the control collar 66 is in register with the intermediate channel 39, so that depending on the pressure difference change to a metering orifice, not shown, the variable swung out (connection with tank pressure) or pivoted back (connection with pump pressure) can be. Further explanations of the function of the pump controller are dispensable with reference to the prior art described above.

The particular advantage of the construction according to the invention with the support of the control spring to an expander is that the valve housing can be extremely simple, since no provision must be made for applying an adjustment and sealing system. The number and complexity of the components when using an expander over the conventional solutions can be significantly reduced, with the tightness problems are largely eliminated, since the sealing contact of the expansion sleeve on the peripheral wall of the spring chamber and the sealing contact of the cone bolt on the inner circumference of the expansion sleeve is readily possible by suitable choice of material and processing, with comparatively low requirements are placed on the surface quality.

It should be understood that the term "valve assembly" or "spring assembly" may also include a single valve or spring.

Disclosed is a hydraulic valve arrangement, in particular a control valve arrangement of a variable displacement pump, wherein a valve piston of a valve is biased by a spring arrangement in a basic position. This spring arrangement is supported on an expander.

Claims

claims

1. Hydraulic valve arrangement, in particular control valve of a variable displacement pump, with a valve housing (2) in which a valve bore (10, 18) is formed in which a valve piston (8, 60) is inserted axially displaceable, by means of a spring (12, 62) is biased in one direction, wherein the spring (12.62) is supported on an at least one time axially adjustable spring seat, characterized in that the spring seat has an expandable expansion sleeve (50), the non-positively into the valve bore (10, 18) or an adjoining spring chamber (48, 74) is inserted.

2. Valve arrangement according to claim 1, wherein the expansion sleeve (50, 84) is associated with a conical bolt (54, 82), which via a pull rod (62), which is preferably designed with a predetermined breaking point, for a radial expansion of the expansion sleeve (50, 84) is adjustable.

3. Valve arrangement according to claim 2, wherein the expansion sleeve (50, 84) is designed such that its spring-side end face extends axially at least about the actuating travel for widening over the cone bolt (54, 82).

4. Valve arrangement according to claim 3, wherein the expansion sleeve (50, 84) in the axial direction a spacer (58, 86) adjoins, which forms the spring-side end face and whose axial length is determined so that the cone bolt (54, 82) in particular in The loose inserted into the expansion sleeve (50, 84) state does not protrude axially over the spacer (58, 86) to the spring.

5. Valve arrangement according to claim 4, wherein the spacer (58, 86) is integral with the expansion sleeve (50, 84) or designed as a separate component.

6. Valve arrangement according to claim 5, wherein the inner diameter of the spacer (58, 86) has a larger diameter than the cone bolt (54, 82) and a larger diameter than the inner diameter of the expansion sleeve (50, 84).

7. Valve arrangement according to one of the claims 4 to 6, wherein between the spacer (58, 86) and the spring (12, 62) a support disc (44, 48) is arranged, which acts as a spring seat for the spring (12, 62) ,

8. Valve arrangement according to one of the preceding claims, wherein the expansion sleeve (50, 84) on its outer circumference has one or more circumferential grooves (56) of any shape.

9. Valve arrangement according to one of the preceding claims, wherein the valve is a flow control valve (4) or a pressure control valve (6) of a pump controller.