Pressure-reducing valve

Abstract

The invention relates to a pressure-reducing valve (1) for regulating a system pressure, comprising a valve housing (2) in which a valve slide (12) is movably guided and which defines an inflow-side chamber (4) and an outflow-side chamber (5). The inflow-side chamber (4) and the outflow-side chamber (5) can be connected together in the valve housing (2) via a passage (19). The valve slide (12) is provided with a closing edge (21) which, in cooperation with the throttling gap (20), forms a throttling point (22) at which a fluid flowing out of the inflow-side chamber (4) into the outflow-side chamber (5) can be throttled on the basis of the respective current position of the valve slide (12) in the valve housing (2). Additionally, at least one flow geometry (26) is provided which causes a turbulent flow of the fluid. The aim of the invention is to provide a pressure-reducing valve (1) in which acoustic disturbances are reduced as much as possible during operation and via which additionally the system pressure can be regulated as reliably as possible. This is achieved in that the at least one flow geometry (26) is provided downstream of the throttling point (22) and causes an at least partial flow deflection of the fluid in the direction of a passage out of the inflow-side chamber (4).

Description

[0001] pressure reducing valve

[0002] The invention relates to a pressure reducing valve for regulating a system pressure, in particular a system pressure prevailing in a fluid system of a vehicle transmission or an electric vehicle drive axle, comprising a valve housing in which a valve spool is displaceably guided and which defines an inlet-side chamber and an outlet-side chamber, wherein the inlet-side chamber and the outlet-side chamber are connected to one another in the valve housing via a passage which forms a throttle gap, wherein the valve spool is provided with a closing edge which, in interaction with the throttle gap, forms a throttle point at which, depending on a respective current position of the valve spool in the valve housing, a fluid flowing from the inlet-side chamber into the outlet-side chamber can be throttled, and wherein at least one flow geometry is provided which causes a turbulent flow of the fluid.Furthermore, the invention relates to a fluid system with at least one aforementioned pressure reducing valve.

[0003] Pressure reducing valves are mostly used in fluid systems to regulate the required system pressure in the respective fluid system. The pressure downstream of the pressure reducing valve is regulated by the pressure after the pressure reducing valve acting, for example, on a feedback surface of a valve spool of the pressure reducing valve. This regulation is usually achieved by throttling the fluid at a throttling point, whereby the degree of throttling in the respective pressure reducing valve is often set based on the position of the valve spool in a valve housing. However, due to the high flow velocities in the cross-section of the throttling point, the throttling of the fluid sometimes results in the development of acoustic disturbances in the form of flow noise. In some cases, additional measures are therefore taken to keep this noise development as low as possible.

[0004] EP 1 384 926 A2 discloses a pressure reducing valve intended for use as a radiator valve in a heating system. This pressure reducing valve comprises a valve housing into which a valve insert is screwed. A valve slide is accommodated in the valve insert, which is guided displaceably between different positions in the valve insert and thus in the valve housing and is preloaded in an opening direction by a spring element. At one end, the valve slide is provided on a closure body with a closing edge, which, together with a throttle gap, forms a throttle point of the pressure reducing valve. The throttle gap is designed at a passage from an inlet-side chamber to an outlet-side chamber.The throttling of a fluid in the form of water occurs depending on the position of the valve spool in the valve insert and thus in the valve housing by appropriately defining the throttling point between the closing edge and the throttling gap. Adjacent to the throttling gap, the closure body is provided with raised portions distributed as knobs or ribs around the circumference of the closure body. These raised portions are intended to generate targeted turbulence in the area of ​​the throttling point, thus reducing acoustic disturbances.

[0005] Based on the prior art described above, it is the object of the present invention to provide a pressure reducing valve in which acoustic disturbances are reduced as far as possible during operation and by means of which, moreover, the most reliable control of a system pressure can be achieved.

[0006] This object is achieved based on the preamble of claim 1 in conjunction with its characterizing features. The dependent claims that follow therefrom each represent advantageous developments of the invention. A fluid system in which at least one pressure reducing valve according to the invention is provided is further the subject of claim 11.

[0007] According to the invention, a pressure reducing valve comprises a valve housing in which a valve spool is slidably guided and which defines an inlet-side chamber and an outlet-side chamber. The inlet-side chamber and the outlet-side chamber in the valve housing can be connected to one another via a passage in certain positions of the valve spool. The valve spool is provided with a closing edge which, in interaction with a throttle gap, forms a throttle point at which, depending on the current position of the valve spool in the valve housing, a fluid flowing from the inlet-side chamber into the outlet-side chamber is throttled. In addition, at least one flow geometry is provided which causes a turbulent flow of the fluid.

[0008] The pressure reducing valve according to the invention therefore has a valve housing in which an inlet-side chamber and an outlet-side chamber are defined. The two chambers can be connected to one another via a passage in the valve housing depending on the position of the valve spool, so that fluid from the inlet-side chamber can pass into the outlet-side chamber via the passage. The inlet-side chamber is in particular also connected to an inlet, which is preferably designed as a connection on the valve housing and via which fluid can be guided into the inlet-side chamber. When the pressure reducing valve according to the invention is installed in a fluid system, a supply line is in particular connected to the inlet. Likewise, the outlet-side chamber is preferably connected to an outlet, which is in particular present as a connection on the valve housing and is provided for draining fluid from the outlet-side chamber.When the pressure reducing valve according to the invention is installed in a fluid system, a discharge line is particularly preferably connected to the outlet. The chambers and also the channels that connect them to the corresponding connections on the valve housing are particularly implemented as recesses formed in the valve housing. The valve housing can be a separate housing, which is mounted at the appropriate location during assembly of the pressure reducing valve according to the invention, or it can be formed by another housing, such as a transmission housing or a housing of a vehicle axle.

[0009] A valve spool is displaceably guided in the valve housing, with a receiving bore preferably being provided in the valve housing for this purpose, in which the essentially cylindrical valve spool can be axially displaced and which also defines the passage between the inlet-side chamber and the outlet-side chamber. Further preferably, the valve spool has at least one cylindrical guide section, at the respective outer diameter of which the valve spool is guided on a corresponding inner diameter of the receiving bore of the valve housing. In particular, however, the valve spool is provided with a plurality of guide sections that are axially spaced from one another.Further preferably, the closing edge of the valve slide is configured at an axial end of one of the guide sections, wherein the closing edge is configured in particular as an edge in the form of a transition from the respective outer diameter of the guide section into a flank that extends substantially radially. Particularly preferably, the flank, in addition to a radial extension, also has an axial extension in the direction of the guide section having the closing edge, so that an undercut is formed in this region.

[0010] The throttling point is defined between the closing edge of the valve spool and the throttle gap, which is formed at the passage between the inlet-side chamber and the outlet-side chamber in the valve housing. The degree of throttling of the fluid flowing from the inlet-side chamber via the passage into the outlet-side chamber is defined by the position of the closing edge relative to the throttle gap, which in turn depends on the position of the valve spool in the valve housing. The position of the valve spool in the valve housing is preferably determined by pressurizing at least one end face of the valve spool with a control pressure, wherein the valve spool is more preferably preloaded in an axial direction by at least one spring element.

[0011] In the context of the invention, “axial” means an orientation in the direction of a longitudinal central axis of the valve spool, while “radial” means an orientation in the diameter direction of the valve spool.

[0012] The pressure reducing valve according to the invention is designed for regulating a system pressure downstream, i.e., in the flow direction after the pressure reducing valve, wherein this system pressure is particularly effective in a fluid system. The fluid is particularly preferably a hydraulic fluid, and in particular oil. Furthermore, the pressure reducing valve is preferably designed for regulating a system pressure in a fluid system of a vehicle transmission or an electric vehicle drive axle.

[0013] The pressure reducing valve according to the invention also features at least one flow geometry that serves to create a turbulent fluid flow. Thus, the pressure reducing valve is designed with at least one geometry that influences the flow of the fluid and thereby creates turbulence in the fluid. In the context of the invention, turbulence is understood to mean, in particular, fluid swirling.

[0014] The invention now encompasses the technical teaching that the at least one flow geometry is provided downstream of the throttle point and causes an at least partial flow deflection of the fluid in the direction of a transition from the inlet-side chamber. In other words, the at least one flow geometry is arranged downstream of the throttle point in the flow direction of the fluid. Due to its respective design, the at least one flow geometry ensures that a flow of the fluid, after flowing over the throttle point, is at least partially deflected as a turbulent flow in the direction of the transition from the inlet-side chamber.

[0015] Such a design of a pressure reducing valve has the advantage that strong turbulence can be generated by diverting the flow of the fluid via the at least one flow geometry in the direction of the transition from the inlet-side chamber. Tests have shown that this strong turbulence then results in increased elimination of acoustic disturbances. Due to the fact that the at least one flow geometry is provided downstream of the throttling point, the pressure-flow characteristic of the pressure reducing valve is advantageously not impaired or only impaired to a very small extent. Overall, this makes it possible to create a pressure reducing valve which, on the one hand, enables reliable control of a system pressure and, on the other hand, ensures only low noise levels during operation.Although the pressure reducing valve of EP 1 384 926 A2 also generates turbulence in the fluid flow in the area of ​​the throttle point, this occurs primarily in the area of ​​the throttle point via the raised portions located adjacent to the closing edge. Furthermore, this does not cause the flow to be deflected toward the inlet-side chamber. Therefore, the turbulence is also less pronounced compared to the solution according to the invention.

[0016] Essential to the invention is that the at least one flow geometry influences the flow of the fluid after the transition over the throttle point in such a way that the flow of the fluid is at least partially deflected in the direction of the transition from the inlet-side chamber. This explicitly does not mean that the fluid flows back into the inlet-side chamber, but only that the flow of the fluid downstream of the throttle point is at least partially deflected toward the inlet-side chamber. This deflection of the flow is brought about by the respective design of the at least one flow geometry.

[0017] According to one embodiment of the invention, the at least one flow geometry is designed with a triangular cross-section. In particular, a tip of this triangular cross-section is oriented in the direction of the transition from the inlet-side chamber. Advantageously, such a cross-section allows a flow deflection of the fluid to be easily realized as a turbulent flow and in the direction of the transition from the inlet-side chamber. In particular, one side of the triangular cross-section is curved, with this side facing the transition from the inlet-side chamber in the triangular cross-section. This makes it possible to realize a fin-like cross-section in which the flow deflection of the fluid according to the invention is achieved via the curved side. The curved side of the cross-section is particularly preferably defined by at least one radius.

[0018] According to one possible embodiment of the invention, the at least one flow geometry is configured on the valve spool at a section with which the valve spool penetrates the outlet-side chamber of the valve housing. In this case, the at least one flow geometry is configured on the valve spool, specifically being provided on a section of the valve spool with which the valve spool lies in its various positions in the outlet-side chamber. This allows the flow of the fluid to be diverted downstream of the throttle point by the fluid encountering the at least one flow geometry configured on the section of the valve spool after entering the outlet-side chamber and thereby being diverted in the direction of the transition from the inlet-side chamber.

[0019] In a further development of the aforementioned design option, the at least one flow geometry is configured circumferentially on the valve spool. Alternatively or additionally, the at least one flow geometry is also rotationally symmetrical. This ensures that the position of the valve spool in the direction of rotation relative to the valve housing is irrelevant, since the at least one flow geometry is positioned correspondingly to the throttle point in every rotational position of the valve spool.

[0020] In a further embodiment of the invention, which can be implemented alternatively or additionally to the aforementioned variants, the at least one flow geometry is configured on the valve housing on an inner wall that defines the outlet-side chamber. In this case, the inventive flow deflection of the fluid is achieved by a corresponding design of the valve housing.

[0021] In a further development of the invention, multiple flow geometries are provided. This allows the fluid to be further swirled during the transition from the inlet-side chamber by having multiple geometries ensure corresponding turbulence. These multiple flow geometries can be configured individually on the valve spool and / or on the valve housing. The geometries can correspond to one another in terms of their design, but they are particularly preferably designed differently from one another. If multiple flow geometries are positioned on the valve spool, they are preferably configured axially consecutively.

[0022] According to one embodiment of the invention, the valve spool can be continuously positioned in different positions within the valve housing. In this case, the pressure reducing valve is designed in the manner of a proportional valve, which also enables continuous throttling of the fluid. Alternatively, the pressure reducing valve according to the invention could also provide discrete positions for the valve spool within the valve housing, between which the valve spool can be moved axially within the valve housing and cannot assume any intermediate positions.

[0023] In a further development of the invention, the valve housing has a receiving bore in which the valve slide is slidably guided. The inlet-side chamber and the outlet-side chamber are each configured annularly around the receiving bore and are each connected to the receiving bore. This achieves a suitable design for the pressure reducing valve according to the invention.

[0024] The invention also relates to a fluid system in which at least one pressure reducing valve according to one or more of the aforementioned variants is provided. This fluid system is, in particular, a system of a vehicle transmission or an electric vehicle drive axle, wherein this fluid system is preferably in the form of a hydraulic system in the form of a hydraulic circuit.

[0025] The invention is not limited to the specified combination of features of the main claim or the dependent claims. Furthermore, possibilities arise for combining individual features, even if they emerge from the claims, the following description of a preferred embodiment of the invention, or directly from the drawings. The reference of the claims to the drawings by the use of reference numerals is not intended to limit the scope of the claims. An advantageous embodiment, which is explained below, is illustrated in the drawings. It shows:

[0026] Fig. 1 is a sectional view of a pressure reducing valve according to a preferred embodiment of the invention; and

[0027] Fig. 2 shows a detail of the pressure reducing valve from Fig. 1.

[0028] Fig. 1 shows a sectional view of a pressure reducing valve 1, which is designed according to a preferred embodiment of the invention and is intended for regulating a system pressure in a hydraulic circuit of a vehicle transmission or an electric vehicle drive axle. The pressure reducing valve 1 comprises a valve housing 2, which is formed by part of a housing of the vehicle transmission or the electric vehicle drive axle and into which a receiving bore 3 is introduced as a stepped bore. In addition, the valve housing 2 is also equipped with an inlet-side chamber 4, an outlet-side chamber 5 and two pressure chambers 6 and 7, each of which is individually designed in a ring shape around the receiving bore 3 and is each connected to the receiving bore 3.A valve slide 12 is accommodated in the receiving bore 3 of the valve housing 2 and is guided axially displaceably in the receiving bore 3 along a longitudinal central axis 13.

[0029] The inlet-side chamber 4 is connected to an inlet 8 of the pressure reducing valve 1, via which hydraulic fluid can be fed into the inlet-side chamber 4, which is ultimately pumped into the hydraulic system by a pressure source such as a pump. The outlet-side chamber 5 is connected to an outlet 9, which is intended to drain hydraulic fluid from the outlet-side chamber 5. In contrast, the two pressure chambers 6 and 7 are each connected to a pressure connection 10 and 11 respectively. In order to regulate the system pressure prevailing in the outlet, its feedback must be provided to the pressure reducing valve 1 and thus the valve spool 12. For this purpose, the pressure reducing valve 1 has a feedback connection 32, which is connected to the outlet and through which the system pressure is effective in a feedback pressure chamber 31.The valve spool 12 is equipped with a plurality of guide sections 14, 15, and 16, each of which guides the valve spool 12 in the surrounding receiving bore 3. Each guide section 14, 15, or 16 guides the valve spool 12 at a respective outer diameter to a respective, corresponding inner diameter of the receiving bore 3. A feedback surface 30 is formed on the valve spool 12 between the guide sections 15 and 16, which, in axial projection, i.e., in the direction of the longitudinal center axis 13, is calculated as an annular differential surface from the outer diameters of the guide sections 15 and 16. The feedback surface 30 lies in a plane perpendicular to the longitudinal center axis 13.

[0030] In the area of ​​the guide section 14, a blind bore 17 is also formed in the valve spool 12 from one axial end, into which a spring element 18 is inserted. This spring element 18, which is designed here as a helical spring, is also supported axially on the valve housing 2 and preloads the valve spool 12 axially in the direction of the pressure chamber 7.

[0031] The valve spool 12 can be continuously arranged in different axial positions within the valve housing 2 and moved between these positions. The respective position is adjusted by the spring element 18 in interaction with the control pressures set in the pressure chambers 6 and 7, as well as the system pressure acting on the feedback surface 30 of the valve spool 12 in the feedback pressure chamber 31. The force from the system pressure on the feedback surface 30 counteracts the force of the spring element 18.

[0032] The system pressure in the hydraulic circuit is regulated via the pressure reducing valve 1 by throttling the hydraulic fluid as it passes from the inlet-side chamber 4 to the outlet-side chamber 5. For this purpose, a passage 19, which is formed by the receiving bore 3 and via which the chambers 4 and 5 in the valve housing 2 are connected to one another, forms a throttle gap 20, at which, in interaction with a closing edge 21 on the valve spool 12 and depending on the axial position of the valve spool 12 in the valve housing 2, a respective throttling is carried out to adjust the system pressure. In this respect, the throttle gap 20 and the closing edge 21 together define a throttle point 22 of the pressure reducing valve 1.

[0033] While the throttle gap 20 is formed at the passage 19, the closing edge 21 is formed at an axial end of the guide section 14, with which the guide section 14 points axially in the direction of the outlet-side chamber 5. As can be seen in particular in a detailed view of the corresponding area in Fig. 2, the closing edge 21 is defined between an outer diameter 23 of the guide section 14 and a flank 24, with which the guide section 14 tapers in the region of its axial end to a smaller outer diameter of the valve spool 12. The flank 24 runs both radially inward and axially in the direction of the guide section 14 and the blind bore 17, so that an undercut of the valve spool 12 is defined.

[0034] As a special feature, the valve spool 12 is provided with a flow geometry 26 on a section 25 that runs axially between the guide section 14 and the guide section 15 and with which the valve spool 12 axially penetrates the outlet-side chamber 5. This flow geometry 26 is intended to swirl the hydraulic fluid behind the throttle point 22 by generating a turbulent flow. For this purpose, the flow geometry 26 causes at least a partial flow deflection of the hydraulic fluid after it has passed over the throttle point 22 in the direction of the transition from the inlet-side chamber 4.

[0035] As can be seen in Fig. 2, the flow geometry 26 is designed to be continuous and rotationally symmetrical on the valve spool 12, wherein the flow geometry 26 essentially has a triangular cross-section 27, the tip 28 of which is oriented in the direction of the transition from the inlet-side chamber 4. Furthermore, one side 29 of the cross-section 27, with which the cross-section 27 faces axially in the direction of the throttle point 22, is curved and thus bent in order to realize the desired flow deflection. The at least partial flow deflection and the resulting turbulent flow of the hydraulic fluid following the throttle point 22 minimizes acoustic disturbances in the area of ​​the throttle point 22, which are caused by flow noise of the hydraulic fluid. At the same time, the pressure reducing valve 1 can be used to reliably regulate a system pressure.

[0036] Reference symbol

[0037] Pressure reducing valve valve housing mounting bore inlet side chamber outlet side chamber pressure chamber pressure chamber inlet outlet

[0038] Pressure connection Pressure connection Valve spool Longitudinal center axis Guide section Guide section Guide section Blind holes Spring element Passage Throttle gap Closing edge Throttle point

[0039] Outer diameter flank

[0040] Section Flow Geometry Cross Section

[0041] Spiege side feedback surface feedback pressure chamber 32 feedback connection

Claims

Patent claims 1. Pressure reducing valve (1) for regulating a system pressure, in particular a system pressure prevailing in a fluid system of a vehicle transmission or an electric vehicle drive axle, comprising a valve housing (2) in which a valve spool (12) is slidably guided and which defines an inlet-side chamber (4) and an outlet-side chamber (5), wherein the inlet-side chamber (4) and the outlet-side chamber (5) in the valve housing (2) can be connected to each other via a passage (19) in a specific position of the valve spool (12), wherein the valve spool (12) is provided with a closing edge (21) which, in conjunction with a throttling gap (20), forms a throttling point (22) at which, depending on the current position of the valve spool (12) in the valve housing (2), a fluid flowing from the inlet-side chamber (4) into the outlet-side chamber (5) can be throttled.and wherein at least one flow geometry (26) is provided which causes a turbulent flow of the fluid, characterized in that the at least one flow geometry (26) is provided downstream of the throttling point (22) and causes at least a partial deflection of the fluid flow in the direction of a transition from the inlet-side chamber (4).

2. Pressure reducing valve (1 ) according to claim 1 , characterized in that the at least one flow geometry (26) is designed with a triangular cross-section (27).

3. Pressure reducing valve (1 ) according to claim 2, characterized in that in the triangular cross-section (27) one side (29) is curved, wherein this side (29) in the triangular cross-section (27) is directed towards the transition from the inlet-side chamber (4).

4. Pressure reducing valve (1 ) according to one of claims 1 to 3, characterized in that the at least one flow geometry (26) on the valve slide (12) is designed on a section (25) with which the valve slide (12) penetrates the outlet-side chamber (5) of the valve housing.

5. Pressure reducing valve (1 ) according to claim 4, characterized in that the at least one flow geometry (26) is designed circumferentially on the valve slide (12).

6. Pressure reducing valve (1 ) according to claim 5, characterized in that the at least one flow geometry (26) is rotationally symmetric.

7. Pressure reducing valve according to one of the preceding claims, characterized in that the at least one flow geometry is designed on the valve housing on an inner wall which defines the outlet-side chamber.

8. Pressure reducing valve according to one of the preceding claims, characterized in that several flow geometries are provided.

9. Pressure reducing valve (1 ) according to one of the preceding claims, characterized in that the valve slide (12) can be positioned steplessly in different positions in the valve housing (2).

10. Pressure reducing valve (1 ) according to one of the preceding claims, characterized in that the valve housing (2) has a receiving bore (3) in which the valve spool (12) is slidably guided, wherein the inlet-side chamber (4) and the outlet-side chamber (5) are each designed in an annular shape around the receiving bore (3) and are each connected to the receiving bore (3).

11. Fluid system, in particular of a vehicle transmission or an electric vehicle drive axle, comprising at least one pressure reducing valve according to one or more of claims 1 to 10.

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