Piston valve and valve piston for a piston valve

Abstract

Piston valve (1), with a valve piston (3) which is received in a guide (2) and is displaceable relative to the guide (2), and which controls or regulates a flow of a medium through the piston valve (1) depending on its switching position, wherein the valve piston (3) is designed as a hollow component through which the medium can flow, having a sleeve-like wall (4) and an end wall (5), wherein at least one recess (6) is made in the sleeve-like wall (4), which is closed in a first switching position of the valve piston (3) and open in a second switching position of the valve piston (3), characterized in that at least one control orifice (18) is made in the end wall (5), which is open independently of the switching position of the valve piston (3), wherein the or each control orifice (18) has a relatively small flow cross-section relative to the or each recess (6).

Description

[0001] The invention relates to a piston valve according to the preamble of claim 1. Furthermore, the invention relates to a valve piston for a piston valve and a hydrodynamic brake of a motor vehicle with such a piston valve.

[0002] In a variety of automotive applications, the flow of a medium, such as hydraulic oil, must be controlled or regulated. In a hydrodynamic brake or flow brake, depending on the oil pump capacity, either the hydraulic oil pressure and flow rate provided by the retarder must be supported by draining an oil reservoir, or, if the oil pump capacity can provide a sufficiently high hydraulic oil pressure and flow rate on its own, the oil reservoir must be additionally filled. Valves are used to control or regulate the flow of a medium.

[0003] A valve designed as a piston valve has a valve piston as the valve body, which controls or regulates the flow of the medium through the piston valve depending on its switching position. Particularly when such a piston valve is used to control or regulate the flow of a medium through lines with large flow cross-sections, the valve piston also has large dimensions and, according to the state of the art, a relatively high weight and thus a high inertia. Such piston valves then have relatively poor response characteristics, since the inertia of the valve piston must be overcome when transferring it between its switching positions.

[0004] DE 10 2007 047 902 A1 discloses a piston valve with a body providing a guide consisting of two partial bodies, in which a valve piston can be displaced against the spring force of a spring element. Depending on the switching position of the valve piston, the flow of a medium is controlled or regulated by the guide of the piston valve.

[0005] DE 27 36 076 A1 discloses a non-return valve with a damping device for liquid lines.

[0006] DE 103 50 022 A1 discloses an engine braking system for a multi-cylinder engine.

[0007] DE 10 2007 033 146 A1 discloses an adjustment valve for adjusting the delivery volume of a positive displacement pump.

[0008] US 2001 / 0 027 773 A1 discloses an engine braking system for generating a decompression valve event in an internal combustion engine.

[0009] US 2 918 083 A discloses a check valve adapted for use in low and high pressure fluid lines.

[0010] US 2 206 356 A discloses a check valve arranged in a pipeline.

[0011] Based on this, the present invention is based on the object of creating a novel piston valve and a valve piston for a piston valve as well as a hydrodynamic brake with such a piston valve.

[0012] This object is achieved by an object according to patent claim 1. According to the invention, the valve piston is designed as a hollow component through which the medium can flow, having a sleeve-like wall and an end wall, wherein at least one recess is introduced into the sleeve-like wall, which recess is closed in a first switching position of the valve piston and is open in a second switching position of the valve piston.

[0013] Because the valve piston in the piston valve according to the invention is designed as a hollow component through which the medium to be controlled or regulated flows, the valve piston, even with large dimensions, has a relatively low weight and thus a relatively low mass inertia. This largely eliminates the delays in the response behavior of the piston valve known from practice. At least one recess is formed in the sleeve-like wall of the valve piston, which is designed as a hollow component. This recess is closed in the first switching position of the valve piston and open in the second switching position of the valve piston.

[0014] Preferably, an outer circumferential surface of the sleeve-like wall interacts with a corresponding sealing surface of the guide in such a way that, in the first switching position of the valve piston, the sealing surface of the guide closes the or each recess in the sleeve-like wall, and in the second switching position of the valve piston, the sealing surface of the guide exposes the or each recess in the sleeve-like wall. The sealing function in the first switching position of the valve piston is therefore provided by the interaction between the sealing surface of the guide and the outer circumferential surface of the sleeve-like wall of the valve piston, wherein the sealing surface of the guide covers the or each recess in the sleeve-like wall of the valve piston in the first switching position of the valve piston. Preferably, a close clearance fit is formed or set between the sealing surface of the guide and the outer circumferential surface of the sleeve-like wall of the valve piston.

[0015] According to a further development, the valve piston has a radially outward-facing collar at an end opposite the end wall. According to a first variant, a spring element is supported on the collar, which presses the valve piston into the first switching position. According to a second variant, a thread is formed on the collar, which a servomotor engages to adjust the valve piston between its switching positions. This can increase functional integration. The collar can be provided with recesses to optimize function and / or weight.

[0016] At least one control orifice is incorporated into the end wall, which is open regardless of the switching position of the valve piston, wherein the or each control orifice has a relatively small flow cross-section relative to the or each recess. A piston valve with such a valve piston is preferably designed as a shuttle valve, which in the first switching position allows a relatively small flow in a first flow direction through the or each control orifice and in the second switching position allows a relatively large flow in a second flow direction opposite to the first flow direction through the or each recess. The design of the piston valve according to the invention as a shuttle valve with at least one control orifice in the end wall of the valve piston is preferred. Such a shuttle valve is advantageously suitable for use in a hydrodynamic brake of a motor vehicle.

[0017] Preferably, several recesses are provided in the sleeve-like wall, evenly distributed around the circumference of the sleeve-like wall. This allows the flow through the valve piston to be optimally adjusted in its second switching position.

[0018] The hydrodynamic brake according to the invention is defined in claim 8.

[0019] Preferred developments of the invention will become apparent from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein: Fig. 1 a schematic perspective view of a first piston valve according to the invention in a first switching position thereof; Fig. 2 a cross section through Fig. 1; Fig. 3 a schematic perspective view of the piston valve of the Fig. 1 in a second switching position thereof; Fig. 4 a cross section through Fig. 3; Fig. 5 a valve piston of the piston valve of the Fig. 1 to 4 in individual representation; Fig. 6 an alternative valve piston of the piston valve in a single view; Fig. 7 a schematic perspective view of a second piston valve according to the invention in a first switching position thereof; Fig. 8 a cross section through Fig. 7; Fig. 9 a schematic perspective view of a third piston valve according to the invention in a first switching position thereof; Fig. 10 a cross section through Fig. 9; Fig. 11 is a schematic perspective view of a fourth piston valve according to the invention in a first switching position thereof; Fig. 12 a cross section through Fig. 11; Fig. 13 is a schematic perspective view of a fifth piston valve according to the invention in a first switching position thereof when used in conjunction with a hydrodynamic brake; Fig. 14 a schematic perspective view of the piston valve of the Fig. 13 in a second switching position thereof; and Fig. 15 a valve piston of the piston valve of the Fig. 13 and Fig. 14 in single representation.

[0020] Fig. 1 to 4 show different schematic views of a piston valve 1 according to the invention according to a first embodiment of the invention, wherein Fig. 1 and Fig. 2 the piston valve 1 in a first switching position and Fig. 3 and Fig. 4 shows the piston valve 1 in a second switching position.

[0021] The piston valve 1 according to the invention has a guide 2, which can be, for example, a housing of the piston valve 1, wherein a valve piston 3 is accommodated in the guide 2 of the piston valve 1 and is displaceable relative to the guide 2 in order to transfer the valve piston 3 and thus ultimately the piston valve 1 between its different switching positions by displacing the valve piston 3 relative to the guide 2. Depending on the switching position of the valve piston 3 in the guide 2, the valve piston 3 regulates or controls a flow of a medium, for example a flow of hydraulic oil, through the piston valve 1. Fig. 5 is the valve piston 3 of the piston valve 1 of the Fig. 1 to 4 shown individually.

[0022] The valve piston 3 of the piston valve 1 is designed as a hollow component through which the medium to be controlled or regulated can flow, having a sleeve-like wall 4 and an end wall 5. At least one recess 6 is made in the sleeve-like wall 4, which in the first switching position of the valve piston 3 (see Fig. 1 and Fig. 2) is closed, and in the second switching position of the valve piston 3 (see Fig. 3 and Fig. 4) is open. In the illustrated embodiment, several recesses 6 are made in the sleeve-like wall 4 of the valve piston 3, which are evenly distributed around the circumference of the sleeve-like wall 4 in order to open the second switching position of the valve piston 3 (see Fig. 3 and Fig. 4) to enable optimal flow through the valve piston 3, which is designed as a hollow component.

[0023] In the example of Fig. 1 to 5, the recesses 6 in the sleeve-like wall 4 of the valve piston 3 are each designed as circular recesses. Other geometric contours of the recesses 6 may also be used.

[0024] How Fig. 2 to 4, an outer surface 7 of the sleeve-like wall 4 of the valve piston 3 interacts with a corresponding sealing surface 8 of the guide 2 in such a way that in the first switching position of the valve piston 3 (see Fig. 1, Fig. 2) the sealing surface 8 of the guide 2 closes or covers the or each recess 6 in the sleeve-like wall 4 of the valve piston 3, whereas in the second switching position of the valve piston 3 (see Fig. 3, Fig. 4) the sealing surface 8 of the guide 2 releases the or each recess 6 of the sleeve-like wall 4 of the valve piston 3.

[0025] In the Fig. The piston valve 1 shown in 1 to 4 is a pressure-controlled piston valve.

[0026] Then, if as in Fig. 2, the pressure Px on a first side of the valve piston 3 is greater than the pressure Py on a second side of the valve piston 3, the valve piston 3 is pressed against a stop 9 on the basis of this pressure gradient, wherein the valve piston 3 then Fig. 1 and Fig. 2, in which the recesses 6 are closed.

[0027] Then, however, if the pressure Py is Fig. 4 is greater than the pressure Px, the valve piston 3 is moved from the Fig. 2 shown first switching position into the one shown in Fig. 4 shown second switching position, whereby the recesses 6 in the sleeve-like wall 4 of the valve piston 3 are then released. In the switching position of the Fig. 4 the valve piston 3 is lifted from the stop 9.

[0028] How Fig. 1 to 4, a radially outwardly directed collar 10 is formed on one end of the valve piston 3 opposite the front side 5, which on the one hand in the first switching position of the Fig. 1 and Fig. 2 and on the other hand in the second switching position of the Fig. 3 and Fig. 4 defines the relative position of the valve piston 3 to the guide 2. Thus, in the first switching position of the Fig. 1 and Fig. 2 the collar 10 rests against the stop 9, whereas in the switching position the Fig. 3 and Fig. 4 the collar 10 comes to rest on a stop 11 provided by the guide 2.

[0029] As already explained, the valve piston 3 of the piston valve 1 is designed as a hollow component through which the medium to be controlled or regulated flows at least in the second switching position of the valve piston 3 or piston valve 1.

[0030] Such a hollow component can be produced cost-effectively as a deep-drawn component.

[0031] Such a hollow component has a low weight and thus a low mass inertia, so that the piston valve 1 according to the invention has a good response behavior.

[0032] The design of the piston valve 1 according to the invention is simple and compact.

[0033] The flow of the medium through the piston valve 1 is not impeded in the second switching position of the valve piston 3.

[0034] A second embodiment of a piston valve 1 according to the invention is shown Fig. 7 and Fig. 8, where the embodiment of the Fig. 7 and Fig. 8 from the embodiment of the Fig. 1 to 4 only in that in the embodiment the Fig. 7 and Fig. 8, a spring element 12 is additionally provided, which is supported on the one hand on the collar 10 of the valve sleeve 3 and on the other hand on the stop 11 of the guide 2. The spring element 12 presses the valve piston 3 into the Fig. 1 and Fig. 2 shown first switching position against the stop 9. To transfer the piston valve 1 of the Fig. 7 and Fig. 8 into a second switching position, the spring force provided by the spring element 12 must be overcome.

[0035] A further embodiment of a piston valve 1 according to the invention with a spring element 12, the spring force of which presses the valve piston 3 into the first switching position, is shown in Fig. 9 and Fig. 10. While in the exemplary embodiment the Fig. 7 and Fig. 8 the valve piston 3 is guided in a bore of the guide 2, is in Fig. 9 and Fig. 10 the valve piston 3 is guided on a projection 13 of the guide 2.

[0036] However, with regard to the design of the valve piston 3, the embodiment of the Fig. 7 and Fig. 8 and the embodiment of the Fig. 9 and Fig. 10 with the examples of Fig. 1 to 4, so that reference can be made to the above statements.

[0037] A further embodiment of a piston valve 1 according to the invention is shown Fig. 11 and Fig. 12. In Fig. 11 and Fig. 12, a thread 14 is formed on the collar 10 of the valve piston 3, to which a servomotor 15 acts via a shaft 17 carrying a counter thread 16 in order to move the valve piston 3 of the piston valve 1 of the embodiment of the Fig. 11 and Fig. 12 controlled or regulated by means of the servo motor 15 between its switching positions. In the embodiment of the Fig. 11 and Fig. 12 is applied to the spring element 12 of the embodiments of the Fig. 7, Fig. 8 and the Fig. 9, Fig. 10 can be omitted. Stop 9 can also be omitted.

[0038] However, with regard to the design of the valve piston 3, the embodiment of the Fig. 11 and Fig. 12 with the embodiment of the Fig. 1 to 4, so reference is made to the above statements. Fig. 6 shows the valve piston 3 of the embodiment of the Fig. 11 and Fig. 12 in single representation.

[0039] A further piston valve 1 with a valve piston 3 designed according to the invention is shown in the embodiment of Fig. 13 to 15, whereby the embodiment of the Fig. 13 to 15 essentially differs from the embodiments described above in that, on the one hand, the recesses 6 in the sleeve-like wall 4 of the valve piston 3 are not circular in cross-section, but rather elongated or oval, and that, in addition, recesses are also made in the end wall 5 of the valve piston 3, namely two control orifices 18 in the embodiment shown. The collar 10 of the valve piston 3 is provided with recesses 23 here.

[0040] Then, if such control orifices 18 are introduced into the end wall 5 of the valve piston 3, the piston valve 1 according to the invention is a so-called shuttle valve, which in the first switching position (see Fig. 13) a relatively small flow exclusively through the or each control orifice 18 in a first flow direction and in the second switching position (see Fig. 14) additionally permits a relatively large flow in a second flow direction opposite to the first flow direction through the or each recess 6. The control orifices 18 therefore have a relatively small flow cross-section, both individually and in total, compared to the recesses 6.

[0041] Fig. 13 and Fig. 14 show a piston valve 1 designed as a shuttle valve in the preferred application in a hydrodynamic brake of a motor vehicle, wherein according to Fig. 13 and Fig. 14 the guide 2 of the valve piston 1 is provided by a nozzle 19 of an oil reservoir 20 of the hydrodynamic brake, wherein the oil reservoir 20 is connected via the shuttle valve 1 to a hydraulic control circuit 21 of the hydrodynamic brake via a flow pipe 22.

[0042] Then, when a retarder (not shown) of the hydrodynamic brake is running and the oil pump output alone can provide a sufficiently high hydraulic pressure in the hydraulic control circuit 21 of the hydrodynamic brake, the shuttle valve 1 takes the Fig. 13, in which the recesses 6 in the sleeve-like wall 4 of the valve piston 3 are closed, whereby the oil reservoir 20 can then be filled from the hydraulic control circuit 21 via the control orifices 18 in the end wall 5 of the valve piston 3. Fig. The flow arrows shown in Figure 13 visualize the filling of the oil reservoir 20 starting from the hydraulic control circuit 21 via the control orifices 18.

[0043] However, when the retarder is switched on and the oil pump output cannot yet provide sufficient hydraulic pressure and oil volume flow in the hydraulic control circuit 21 of the hydrodynamic brake during start-up or acceleration, the retarder can be supported in providing the hydraulic pressure and oil volume flow for the hydraulic control circuit 21 by emptying the oil reservoir 20, whereby the shuttle valve 1 then Fig. 14, in order to then empty the oil reservoir 20 into the hydraulic control circuit 21, namely via the recesses 6 in the sleeve-like wall 4 of the control piston 3.

[0044] What all embodiments have in common is that a valve piston 3 designed as a hollow component is used, through which the medium to be controlled or regulated flows in at least one switching position of the piston valve 1.

[0045] This valve piston 3 can be easily and cost-effectively manufactured from sheet metal using a deep-drawing process and is lightweight. Therefore, a piston valve 1 with a simple, compact design and good responsiveness can be provided.

[0046] Due to a relatively tight clearance fit between the sleeve-like wall 4 of the valve piston 3 and the guide 2 for the valve piston 3, the sealing function for the recesses 6 can be easily adjusted in the first switching position.

[0047] Then, if control orifices 18 are additionally incorporated in the end wall 5 of the valve piston 3, a shuttle valve can be provided.

[0048] Then, when the piston valve 1 assumes the second switching position in which the recesses 6 in the sleeve-like wall 4 of the valve piston 3 are released, the flow through the piston valve 1, in particular the valve piston 3 thereof, is not impeded. Reference symbol 1 piston valve 2 Guide 3 valve pistons 4 sleeve-like wall 5 Front wall 6 Recess 7 Shell surface 8 Sealing surface 9 stop 10 collars 11 stop 12 spring element 13 lead 14 threads 15 Actuator 16 counter threads 17 Wave 18 Control panel 19 nozzles 20 oil storage tanks 21 hydraulic control circuit 22 Flow tube 23 recesses

Claims

[1] Piston valve (1), comprising a valve piston (3) received in a guide (2) and displaceable relative to the guide (2), which, depending on its switching position, controls or regulates a flow of a medium through the piston valve (1), wherein the valve piston (3) is designed as a hollow component through which the medium can flow, with a sleeve-like wall (4) and an end wall (5), wherein at least one recess (6) is provided in the sleeve-like wall (4), which is closed in a first switching position of the valve piston (3) and open in a second switching position of the valve piston (3), characterized by , that at least one control orifice (18) is provided in the end wall (5) which is open independently of the switching position of the valve piston (3), wherein the orifice (18) orifice has a relatively small flow cross-section in relation to the or recess (6). [2] Piston valve (1) according to claim 1, characterized by, that an outer surface (7) of the sleeve-like wall (4) interacts with a corresponding sealing surface (8) of the guide (2) such that in the first switching position of the valve piston (3) the sealing surface (8) of the guide (2) closes the or each recess (6) in the sleeve-like wall (4), and that in the second switching position of the valve piston (3) the sealing surface (8) of the guide (3) releases the or each recess (6) in the sleeve-like wall (4). [3] Piston valve (1) according to claim 1 or 2, characterized by , that several recesses (6) are provided in the sleeve-like wall (4) which are evenly distributed around the circumference of the sleeve-like wall (4). [4] Piston valve (1) according to any one of claims 1 to 3, characterized by , that the valve piston (3) has a collar (10) directed radially outwards at one end opposite the end wall (5). [5] Piston valve (1) according to claim 4, characterized by, that a spring element (12) is supported on the collar (10), which pushes the valve piston (3) into the first switching position. [6] Piston valve (1) according to claim 4, characterized by , that a thread (14) is formed on the collar (10), on which an actuator (15) engages to adjust the valve piston (3) between its switching positions. [7] Piston valve (1) according to claim 1, characterized by , that the same is designed as a changeover valve which in the first switching position allows a relatively small flow in a first flow direction through the or each control orifice (18) and in the second switching position allows a relatively large flow in a second flow direction opposite to the first flow direction through the or each recess (6). [8] Hydrodynamic brake of a motor vehicle, comprising a retarder, an oil accumulator (20), a hydraulic control circuit (21) and a piston valve (1) connected between the oil accumulator (20) and the hydraulic control circuit (21), wherein in a first switching position of the piston valve (1) the oil accumulator (20) can be filled and in a second switching position of the piston valve (1) when or immediately after switching on the retarder the oil accumulator (20) can be emptied to increase the oil volume flow for the retarder, wherein the piston valve (1) is designed according to one of claims 1 to 7.

Images