Valve

Abstract

A valve (1) for controlling fluids, in particular hydraulic fluid, comprising a first connection opening (4) and a second connection opening (5), a preliminary stage (2) with a first valve seat (7) and a first displaceable closing body (6), and a main stage (3) with a second valve seat (19) and a second displaceable closing body (13), wherein the second closing body (13) has a flow opening (15) to which the first valve seat (7) is assigned, wherein the second closing body (13) has at least one flow channel (26, 29) which forms a flow path from the first connection opening (4) to the preliminary stage (2), wherein at least one filter device (35) is formed in the flow path, wherein the second closing body (13) has a first flow channel (26) which runs radially inward from a casing outer side of the second closing body (13), and at least one second flow channel (29),which extends axially through the second closing body (13) from an end face of the second closing body (13) associated with the first valve seat (7) to the first flow channel (26), characterized in that the first flow channel (26) is designed as a multi-stage annular groove (27) which extends over the entire circumference of the second closing body (13).

Description

[0001] The invention relates to a valve, in particular a solenoid valve, for controlling fluids, in particular hydraulic fluid, comprising a first connection opening and a second connection opening, a preliminary stage with a first valve seat and a first displaceable closing body, and a main stage with a second valve seat and a second displaceable closing body, wherein the second closing body has a through opening to which the first valve seat is assigned. State of the art

[0002] Valves of the type mentioned above are known from the prior art. In automotive engineering, such valves are used, for example, in hydraulic brake systems to control the inlet or outlet of gases or liquids, in particular brake fluid, or to control and regulate the flow direction. Various devices are known in the field of brake systems in which an active or partially active pressure build-up is realized via a particularly two-stage valve that has a pre-stage and a main stage. The valve is often designed as a high-pressure switching valve, the activation / actuation of which opens a flow path between a master brake cylinder (primary circuit) and a pump element (secondary circuit). The two-stage design enables the valve to be opened or the flow path to be opened even at high differential pressures.The primary circuit is connected to the first connection opening (first fluid connection) and the secondary circuit to the second connection opening (second fluid connection), between which the two closing bodies are located. The first connection opening is usually assigned a first filter element, which serves to retain larger dirt particles that should not enter the primary circuit. If the pressure conditions cause the flow path to lead from the second connection to the first connection, the corresponding dirt particles are collected on the filter element. If the pressure conditions change so that the flow path leads from the first connection to the second connection, the dirt particles are removed again and directed towards the pre-stage.However, since the pre-stage usually has a small stroke and a small flow opening, larger dirt particles can cause the pre-stage to jam or become blocked, which can lead to a malfunction of the valve.

[0003] Valves for controlling fluids are known, for example, from the published patent applications DE 10 2008 023 112 A1, DE 10 2013 223 103 A1 and US 2006 / 0 289 815 A1. Disclosure of the invention

[0004] The valve according to the invention with the features of claim 1 has the advantage that jamming and / or clogging of the pre-stage is prevented in a simple manner. According to the invention, it is provided that the second valve body has at least one flow channel which forms a flow path from the first connection opening to the pre-stage, wherein at least one filter device is formed in the flow path. The second closing body thus has a filter device which accordingly filters the fluid flowing through the flow path. The filter device is arranged in a flow channel of the second closing body, so that the filter device is completely integrated into the second closing body. The flow channel forms a flow path from the first connection opening to the pre-stage, so that fluid is conducted from the filter to the pre-stage through the flow channel when appropriate pressure conditions exist.By integrating the filter device into the flow channel, the filter device can be easily integrated into the valve. The flow channel is characterized in that it is formed solely by the second closing body and extends through the second closing body. Preferably, a filter element, in particular a radial filter, is assigned to the first connection opening. Particularly preferably, it is also provided that the first closing body and the second closing body are axially displaceable. According to a particularly advantageous embodiment of the invention, the valve is designed as a two-stage valve.

[0005] Expediently, a particularly displaceable actuating element, such as a magnetic armature, is assigned to the first closing body for its displacement.

[0006] According to the invention, the second closing body has a first flow channel which runs at least substantially radially inwards from an outer side of the casing of the second closing body, and at least one second flow channel which runs at least substantially axially through the second closing body from an end face of the closing body assigned to the first valve seat to the first flow channel. The first flow channel and the second flow channel are thus directly connected to one another in fluid terms, wherein their respective orientation means a flow deflection for the fluid guided through the flow path. The two flow channels are preferably designed as bores or Sachlock bores. Alternatively, it is preferably provided that the two flow channels are already taken into account during manufacture of the valve body by means of a casting mold or the like.The first flow channel is expediently formed in a region of the second closing body which is always in fluid communication with the first connection opening.

[0007] Preferably, the filter device comprises a filtering gap formed by a constriction of the flow path. It is therefore provided that a flow cross-section of the flow path is correspondingly tapered or narrowed to form a filtering gap. The size of the filtering gap is selected such that undesirably large dirt particles are retained therein. By providing a simple filtering gap, the filter device's effectiveness is ensured in a simple manner, so that the manufacture of the valve does not result in particularly high costs. Particularly preferably, the filtering gap is assigned to the first flow channel, so that the constriction is located in the radially extending section of the flow path upstream of the flow deflection.

[0008] Furthermore, it is preferably provided that the filtering gap is provided only in a radially inner section of the first flow channel. This results in a radially further outer section of the first flow channel having a larger cross-section, into which the fluid can flow from the outside. The larger outer cross-section of the first flow channel also ensures that any dirt particles retained in the filtering gap can be removed again.

[0009] According to an advantageous development of the invention, several first flow channels are arranged around the circumference, in particular evenly distributed over the circumference of the second closing body. The first flow channels are formed in a spoke-like manner in the second closing body. The more first flow channels are provided and the larger their respective cross-sections, the higher the flow rate of the fluid. In particular, the cross-section narrowed by the filter gap can be compensated for by providing several first flow channels.

[0010] According to the invention, the first flow channel is designed as a multi-stage annular groove extending over the entire circumference of the second closing body. The annular groove is designed in multiple stages to form, on the one hand, the radially outer section with a larger cross-section and, on the other hand, the radially inner section of the filtering gap. The second flow channel expediently opens into the inner section that forms the filtering gap.

[0011] Particularly preferably, a plurality of second flow channels are provided, which are also distributed over the circumference, in particular evenly, of the second closing body. The number of second flow channels preferably corresponds to the number of first flow channels. If the first flow channel is designed as a multi-stage annular groove, a plurality of second flow channels are expediently provided, which open into the inner section of the annular groove.

[0012] According to an alternative embodiment, the filter device comprises a filter screen formed integrally with the second closing body. The filter screen is particularly preferably formed in the respective second flow channel. In contrast to the filtering gap, the provision of the filter screen allows the free filter surface to be significantly increased, thereby resulting in lower flow resistance. The filter screen is particularly preferably arranged in the second flow channel at the transition from the first flow channel to the second flow channel.

[0013] According to an advantageous development of the invention, the second closing body is formed in at least two parts. In this case, the first and / or the second flow channel is preferably formed by a first part and a second part of the closing body. This allows the closing body to be manufactured particularly easily and cost-effectively.

[0014] Particularly preferably, a portion of the two-part second closing body is made of a ferritic material. This eliminates the need for a compression spring acting on the valve body, which is otherwise typically provided, since the ferritic portion of the valve body is already pulled toward the armature by the armature or the valve's actuating element when a corresponding magnetic field is present.

[0015] The invention will be explained in more detail below using exemplary embodiments. These show: Fig. 1 a two-stage solenoid valve in a longitudinal section, Fig. 2 a detailed view of the solenoid valve with an advantageous further development, Fig. 3 a detailed view of the solenoid valve with a further advantageous development and Fig. 4 a longitudinal sectional view of a closing body of the solenoid valve with an advantageous further development.

[0016] Fig. 1 shows a simplified longitudinal sectional view of a two-stage valve 1 designed as a high-pressure solenoid valve for a braking system of a motor vehicle. The valve 1 has a pilot stage 2 and a main stage 3, with the pilot stage 2 and the main stage 3 both being arranged between a first connection opening 4 and a second connection opening 5 of the valve 1. The connection opening 4 serves to connect the valve 1 to a primary circuit of the braking system, such as a master brake cylinder, and the second connection opening 5 serves to connect the valve 1 to a secondary circuit, such as a pump device.

[0017] The pre-stage 2 is formed by a first closing body 6, which in this case is designed as a valve ball, and a first valve seat 7. The valve body 6 is fixedly connected to an actuating element 8, which is axially displaceable in a first valve sleeve 9.

[0018] To move the actuating element 8, a pole core 10 is arranged in the valve sleeve 9 at an axial distance therefrom, to which pole core 10 is assigned a magnetic coil (not shown here). By energizing the magnetic coil, a magnetic field is generated by means of the pole core 10, which draws the actuating element 8, which is designed as a magnetic armature, in the direction of the pole core 10. A compression spring 11, in this case in the form of a helical spring, is preloaded between the pole core 10 and the actuating element 8, against which the actuating element is pulled to actuate the valve 1. In this respect, the valve 1 is a normally closed solenoid valve. In the unactuated state, the helical spring 11 urges the first closing body 6 against the first valve seat 7 by means of the actuating element 8. The actuating element 8 projects axially in regions into a second valve sleeve 12, in which the pre-stage 2 or the first valve seat 7 is located.

[0019] The first valve seat 7 is formed by a second closing body 13, which is arranged axially displaceably in the second valve sleeve 12. A further compression spring 14, in this case in the form of a helical spring, is assigned to the second closing body 13, which urges the second closing body 13 in the direction of the actuating element 8. The second closing body 13 has a through-opening 15, to which the first valve seat 7 is assigned. Thus, the through-opening 15 is closed by the first closing body 6 when the solenoid valve 1 is not actuated.

[0020] The second closing body 13 has an axial section 16 that projects through an end-face opening 17 of the valve sleeve 12. The valve 1 further has a third valve sleeve 18, which is designed in particular in the manner of a deep-drawn part with multiple stages. The valve sleeve 12 and the axial section 16 project into the third valve sleeve 18, wherein the third valve sleeve 18 forms a second valve seat 19, which interacts with the closing body 13 to form the main stage 3. The valve sleeve 18 has the connection opening 5 at its free end. The valve sleeve 18 is arranged in a valve housing 20, which radially has the connection opening 4. The valve sleeve 18 has a plurality of radial openings 21, which are distributed over the circumference of the valve sleeve 13 and which are located axially at the level of the connection opening 4.The valve sleeve 12 has a plurality of radial openings 25 through which the hydraulic medium can flow from the connection opening 4 to the pre-stage 2. If the pressure in the pre-stage 2 becomes sufficiently high, the closing body 6 detaches from the valve seat 7, so that the flow opening 15 is opened and the hydraulic medium reaches the connection opening 5.

[0021] The connection opening 4 is also assigned a filter 22 which is designed to retain larger dirt particles.

[0022] If the pressure in the secondary circuit is greater than in the primary circuit, the hydraulic fluid will release the closing body 13 from the second valve seat 19 and flow to the connection opening 4 through the filter 22, as indicated by an arrow 23, with larger dirt particles possibly being retained in the filter 22. If the pressure conditions are reversed, the hydraulic fluid flows from the primary circuit into the secondary circuit, as indicated by an arrow 24. The dirt particles released from the filter 22 can cause the pre-stage 2 to become blocked.

[0023] Fig. 2 shows an enlarged detailed view of the valve 1, an advantageous further development which prevents dirt particles released by the filter 22 from blocking the pre-stage 2. For this purpose, the radial openings 25 are dispensed with and the valve sleeve 12 is closed to this extent. Instead, a flow path is provided which runs directly through the second closing body 13. For this purpose, the second closing body 13 has a first flow channel 26 which runs radially inwards from an outer side of the casing of the closing body 13. According to the present exemplary embodiment, the first flow channel 26 is designed as an annular groove 27. The annular groove has a step, so that the inwardly running first flow channel 26 has an inner section with a small cross-section and a further outer section with a larger cross-section.The (flow) cross-section of the inner section is selected so narrow that only dirt particles with a maximum permissible size can enter this section. The narrow section of the flow channel 26 thus forms a filter gap 28 as a filter device 35.

[0024] A plurality of second flow channels 29 run axially from an end face 30 assigned to the first closing body 6 to the flow channel 26 or the annular groove 27, wherein the flow channels 29 open into the section of the flow channel 26 with the smaller cross-section. The flow channels 29 are preferably arranged so as to be evenly distributed over the circumference of the closing body 13. The annular groove 27, which is designed as a multi-stage annular groove due to the narrowing of the flow channel 26, is arranged in an axial section of the closing body 13 that is always arranged outside the valve sleeve 12, so that a fluidic connection always exists between the connection opening 4 and the pre-stage 2 through the flow channels 26 and 29. Furthermore, the closing body 13 lies essentially radially tightly against the valve sleeve 12, so that a fluidic connection is preferably only provided through the flow channels 26 and 29.

[0025] The flow channels 29 open into the inner section of the flow channel 26 in such a way that the filtering gap 28 remains towards the outside and, preferably towards the inside, the annular groove extends somewhat further into the material of the closing body 13, so that a collecting pocket 31 is formed. When the hydraulic medium now flows from the connection opening 4 into the flow channel 26, the hydraulic medium is first filtered through the filtering gap 28, so that dirt particles are prevented from reaching the pre-stage 2. The flow is then diverted by approximately 90° into the flow channels 29, whereby the flow diversion results in any dirt particles still present in the hydraulic medium being carried into the receiving pocket 31 and retained there. The hydraulic medium then flows through the flow channels 29 to the pre-stage 2, as previously described.

[0026] The flow channels 29 advantageously have a conical longitudinal section, which, on the one hand, offers fluidic advantages and, on the other hand, facilitates the production of the closing body 13 through a casting process. Alternatively, the flow channels 26 and / or 29 can also be subsequently introduced into the closing body 13 by machining. By providing a plurality of flow channels 29 and the annular groove 27, or alternatively a plurality of flow channels 26, pressure drops are reduced. The length of the filter gap 28 is preferably selected to be short in order to keep the pressure drop of the flow as low as possible at this point as well.

[0027] Fig. 3 shows a detailed view of Fig. 2 with an advantageous further development. Here, the transition from the flow channel 26 to one of the flow channels 29 is shown. In contrast to the previous exemplary embodiment, in this exemplary embodiment the flow channel 26 does not have a taper or constriction that would form a filtering gap 28. Instead, it is provided that a filter screen 32 is provided as the filter device 35, which lies in the flow channel 29. The filter screen 32 is preferably formed integrally with the closing body 13. The geometry of the filter screen 32 is expediently already taken into account during the manufacture of the closing body 13 in the corresponding injection mold. In particular, it is provided that a pin is provided for each of the flow channels 29, the end of which pin has a geometry corresponding to the filter screen.In contrast to the filter gap 28, the provision of the filter screen 32 allows the free filter surface to be significantly increased, thereby further reducing the flow resistance. Furthermore, this allows for a more stable design of lateral slides in an injection molding tool. As an alternative to the illustrated embodiment, the . Fig. 3, it is also conceivable to provide the filter screen in the flow channel 26. It is also conceivable to form a corresponding filter screen in both flow channels 26 and 29. According to a further alternative embodiment, the respective flow channel 29 has a taper or constriction that forms a corresponding filtering gap.

[0028] Fig. 4 shows a longitudinal sectional view of a further embodiment of the closing body 13. In contrast to the previous embodiments, the closing body 13 is now formed in two parts, with the dividing line running along the flow path or the flow channels 26 and 29. As a result, the flow channels 26 and 29 are each formed by a first inner part 33 and a second outer part 34 of the closing body 13. The two parts 33 and 34 are firmly connected to one another. For this purpose, for example, a positive or non-positive connection can be provided. In particular, it is provided that the two parts 33 and 34 form an interference fit, are fastened to one another by a friction weld, or have a snap-in, particularly latching, connection.The two-part design of the closing body 13 makes the production of the flow channels 26 and 29 easier than in the previous embodiments. Pressure drops can also be further minimized through clever flow guidance. According to this embodiment, it is also provided that the flow channels 29 each have a circular ring-segment-shaped cross-section. The radial webs located between adjacent flow channels 29 preferably bear sealingly against the inside of the part 34, with the design of these webs being selected such that they form a press fit with the part 34. The filtering gap 28 can also, as shown in FIG. Fig. 4, in the flow channels 29 or extending axially instead of radially. In particular, the filter gap 28 is formed by the parts 33 and 34 together.

[0029] While the two parts 33 and 34 can in principle be made of the same material, according to the present exemplary embodiment, it is also provided that at least part 34 is made of a ferritic material. In an existing magnetic field, which is generated, for example, by the magnetic coils, the closing body 13 is then drawn toward the actuating element 8. This makes it possible to dispense with the spring element 14. As an alternative to the present exemplary embodiment, it is also conceivable to manufacture both parts 33 and 34 or the one-piece closing body 13 from a ferritic material. It is also conceivable to manufacture only part 33 from the ferritic material.

[0030] Of course, according to a further embodiment (not shown), it is conceivable to design the valve 1 with more than just two valve stages. It is also conceivable for the first and / or second closing bodies 6, 13 to be mounted not axially, but rather radially displaceable or rotatable, for example.

Claims

[1] Valve (1) for controlling fluids, in particular hydraulic fluid, comprising a first connection opening (4) and a second connection opening (5), a preliminary stage (2) with a first valve seat (7) and a first displaceable closing body (6), and a main stage (3) with a second valve seat (19) and a second displaceable closing body (13), wherein the second closing body (13) has a flow opening (15) to which the first valve seat (7) is assigned, wherein the second closing body (13) has at least one flow channel (26, 29) which forms a flow path from the first connection opening (4) to the preliminary stage (2), wherein at least one filter device (35) is formed in the flow path, wherein the second closing body (13) has a first flow channel (26) which runs radially inward from a casing outer side of the second closing body (13), and at least one second flow channel (29),which extends axially through the second closing body (13) from an end face of the second closing body (13) associated with the first valve seat (7) to the first flow channel (26), , characterized by that the first flow channel (26) is designed as a multi-stage annular groove (27) which extends over the entire circumference of the second closing body (13). [2] Valve according to claim 1, characterized by that the filtering device (35) has a filtering gap (28) formed by a narrowing of the flow path. [3] Valve according to claim 2, characterized by that the filtering gap (28) is assigned to the second flow channel (29) or the first flow channel (26), wherein the filtering gap (28) is provided in particular only in a radially inner section of the first flow channel (26). [4] Valve according to one of the preceding claims, characterized bythat a plurality of first flow channels (26) are arranged distributed over the circumference, in particular uniformly over the circumference of the second closing body (13). [5] Valve according to one of the preceding claims, characterized by that a plurality of second flow channels (29) are provided, which are distributed over the circumference, in particular uniformly over the circumference of the second closing body (13). [6] Valve according to one of the preceding claims, characterized by that the filter device (35) has a filter screen (32) formed integrally with the second closing body (13). [7] Valve according to one of the preceding claims, characterized by that the second closing body (13) is formed in at least two parts. [8] Valve according to one of the preceding claims, characterized by that a part (34) of the two-part second closing body (13) is made of a ferritic material.

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