Solenoid valve

Abstract

Solenoid valve (1) comprising a magnetic armature (3) axially displaceable in a valve housing (2) and at least one valve element (25, 26) operatively connected to the magnetic armature (3), wherein the valve element (25, 26) is displaceable by means of the magnetic armature (3) for opening or closing at least one valve seat (11, 13) of the solenoid valve (1), and wherein at least one flow path (24) is formed between the valve housing (2) and the magnetic armature (3) and / or the valve element (25, 26), characterized by a flow restrictor element (27) provided in the flow path (24), which is axially displaceable between a first end stop (28) formed by the magnetic armature (3) and a second end stop (29) formed by the valve element (25, 26).

Description

[0001] The invention relates to a solenoid valve, comprising a magnet armature arranged axially displaceably in a valve housing and at least one valve element operatively connected to the magnet armature, wherein the valve element is displaceable by means of the magnet armature to release or close at least one valve seat of the magnet valve, and wherein at least one flow path is formed between the valve housing and the magnet armature and / or the valve element. State of the art

[0002] Solenoid valves of the type mentioned above are known from the prior art. For example, the document JP H07-35 874 U shows a solenoid valve with a valve housing and an axially displaceable magnet armature. A sealing ring is arranged on the magnet armature, which forms a sealing contact with the valve housing. The sealing ring has an opening for throttling a fluid flow occurring between the valve housing and the magnet armature.

[0003] The prior art also includes document DE 10 2008 001 864 A1.

[0004] The magnet armature of the solenoid valve can be acted upon, for example, by at least one coil in such a way that it is axially displaced and in the process positions the valve element to release or close the valve seat. The magnet armature or the valve element can additionally be operatively connected to a spring element, which creates a spring force that urges the magnet armature or the valve element towards the respective rest position or initial position. The rest position can be a release position in which the valve seat is at least partially released by the valve element, or a closed position in which the valve element closes the valve seat. In the former case, the solenoid valve is a normally open solenoid valve, in the latter case a normally closed solenoid valve.The solenoid valve can, for example, be designed as a high-pressure switching valve (HSV) and used in a driver assistance system. The driver assistance system could be, for example, an ESP, ASR, or ABS system.

[0005] A flow path is provided to enable pressure equalization between fluid chambers located on different sides of the magnet armature during displacement of the magnet armature or valve element. This flow path lies between the valve housing and the magnet armature and / or the valve element. When the magnet armature is displaced, the fluid in the magnet valve can flow along the flow path, passing from one of the fluid chambers into another. Because the flow path usually has only a small volume, i.e. the distance between the valve housing and the magnet armature or valve element is relatively small, the fluid flowing along the flow path is greatly accelerated. Consequently, when the magnet armature or valve element is displaced, the fluid flows through the flow path at high speed.If the fluid encounters a hydraulic stop, it is suddenly decelerated, creating high pressure at that point. This impact of the fluid on the hydraulic stop (for example, an area of ​​the solenoid armature or the valve seat) causes pressure waves to develop, generating noises that can be perceived as unpleasant.

[0006] This is particularly the case if the solenoid valve is multi-stage, especially two-stage, and therefore has a pilot stage and a main stage, and / or if the solenoid valve has a large stroke. At high differential pressures between an inlet and an outlet of the solenoid valve, for example, ≥ 30 bar, only the pilot stage can be opened. This causes the differential pressure to drop. If the differential pressure drops sufficiently, the main stage is forced open, for example, at a differential pressure of ≤ 10 bar. The disturbing noises occur particularly when the main stage opens or closes in a depressurized state. Disclosure of the invention

[0007] In contrast, the solenoid valve with the features recited in claim 1 has the advantage that the noise generated when the solenoid valve is switched or when the magnet armature and / or the valve element are displaced is reduced. At the same time, the switching time of the solenoid valve should not be influenced, or at least not significantly influenced. This is achieved according to the invention with a flow throttle element provided in the flow path, which is arranged between a first end stop, in particular formed by the magnet armature, and a second end stop, in particular formed by the valve element. The flow throttle element effects hydraulic damping in the flow path. In this way, the velocity of the fluid is reduced, so that the generation or transmission of pressure waves in the fluid is prevented or the pressure waves are attenuated.According to the invention, the flow throttle element is mounted so as to be freely movable between the first and second end stops, i.e., it is arranged so as to be axially displaceable between the first and second end stops. However, the displacement of the flow throttle element is limited by the two end stops. The first stop is preferably formed by the magnet armature, and the second end stop is preferably formed by the valve element. Due to its throttling effect, the flow throttle element causes noticeable damping in the gap flow in the flow path, i.e., between the valve housing and the magnet armature and / or the valve element; the pressure wave created in the fluid by the displacement of the magnet armature or the valve element is thus no longer transmitted unhindered.

[0008] The extent of damping caused by the flow throttle element can be adjusted, among other things, via the distance between the first and second end stops. If the flow throttle element is held stationary between the two end stops, the throttling effect of the flow throttle element begins immediately when the magnet armature or valve element is displaced. If, on the other hand, the first and second end stops are spaced apart in such a way that the flow throttle element is not permanently in contact with both the first and second end stops, but is movable between them, the flow throttle element only begins to exert its throttling effect when the magnet armature or valve element has moved far enough that the flow throttle element has come into contact with either the first or second end stop.The axial displacement of the flow restrictor element only occurs when it is in contact with only one of the two end stops, not the first and second. In such a design, the flow restrictor element is not held stationary between the end stops, but rather is movable or displaceable between them.

[0009] The flow restrictor element is preferably geometrically simple, for example, in the form of a ring disk. It can be installed in the solenoid valve without structural modifications to the existing standard components. The additional flow restrictor element is therefore a very cost-effective and effective solution for reducing noise generation in the solenoid valve. Only one additional step is required during assembly of the solenoid valve: inserting the flow restrictor element into the solenoid valve.

[0010] A further development of the invention provides that the valve element has at least one closing element assigned to the valve seat, wherein in particular an intermediate piece of the valve element establishes an operative connection between the magnet armature and the closing element. The closing element is a component of the valve element. It interacts with the valve seat to either open or close it. In the former case, the closing element is spaced from the valve seat, preferably in the axial direction of the solenoid valve; in the latter case, the closing element lies sealingly in the valve seat. Preferably, a closing element is provided for each valve seat of the solenoid valve, each of which belongs to the valve element. The valve element can additionally have the intermediate piece, via which the operative connection between the magnet armature and the closing element is established.This means that if the magnet armature is displaced, this displacement is at least partially transferred to the locking element. However, the locking element can also be attached to the magnet armature, eliminating the need for an intermediate piece. If multiple locking elements are provided, for example, one of the locking elements can be attached to the magnet armature and another of the locking elements can be operatively connected to it.

[0011] A further development of the invention provides that the valve element has several closing elements, each closing element being designed to open or close a respective valve seat. It is initially irrelevant whether the valve seats are connected fluidically one after the other or in parallel. In the former case, the solenoid valve is designed as a multi-stage solenoid valve.

[0012] A further development of the invention provides that one of the closing elements is assigned to a preliminary stage and another of the closing elements to a main stage of the solenoid valve. The solenoid valve is therefore multi-stage, in particular two-stage. As already explained above, when there are high differential pressures between an inlet and an outlet of the solenoid valve, the closing element of the preliminary stage is first displaced in order to release the corresponding valve seat. In this way, a flow connection is established between the inlet and the outlet of the solenoid valve, whereby the differential pressure drops. Once the differential pressure has dropped sufficiently, the closing element of the main stage is finally displaced so that it, too, releases the corresponding valve seat.

[0013] A further development of the invention provides that the intermediate piece encompasses the magnet armature at least in part and / or is attached to it. The intermediate piece thus has, for example, retaining arms that engage the magnet armature, or is at least partially sleeve-shaped to encompass the magnet armature. Preferably, the intermediate piece is firmly connected to the magnet armature, so that a displacement of the magnet armature acts directly on the intermediate piece, causing it to be displaced accordingly.

[0014] A further development of the invention provides that the flow throttle element is designed as an annular disc. The annular disc has a circular cross-section, viewed in the axial direction of the solenoid valve, and a central recess which also has a circular cross-section. The annular disc is preferably arranged such that the magnet armature extends through the central recess at least in part. The annular disc is therefore mounted on the magnet armature so that guidance is provided in the axial direction. The annular disc can have at least one axial bore, via the dimensions of which the throttling effect of the annular disc can be adjusted. Instead of or in addition to the axial bore, at least one open-edged axial opening, which is designed, for example, as a notch, can also be provided on the outer or inner contour of the annular disc.

[0015] A further development of the invention provides that the first end stop is formed by an annular step of the magnet armature and / or the second end stop is present on an end face of the intermediate piece. The annular step is formed by a change in the cross-sectional size of the magnet armature. Preferably, the magnet armature is circular in cross-section when viewed in the axial direction of the solenoid valve, so that the annular step is in the form of a change in the diameter of the magnet armature. If the flow throttle element is designed as an annular disc, the region of the smaller diameter of the magnet armature can penetrate the central recess of the annular disc and the magnet armature can simultaneously provide the first end stop in the region of the change in diameter or the annular step. Additionally or alternatively, the second end stop is present on the end face of the intermediate piece.

[0016] A further development of the invention provides that the flow restrictor element has a flow passage between its outer wall and the valve housing and / or between its inner wall and the magnet armature. The flow restrictor element is thus spaced from the valve housing and / or the magnet armature in such a way that the flow passage is present, through which the fluid can flow upon displacement of the magnet armature or the valve element. The flow restrictor element thus merely throttles the fluid flow, reducing its velocity, but does not block the flow path.

[0017] A further development of the invention provides that the distance between the outer wall and the valve housing, the distance between the inner wall and the magnet armature and / or an axial extension of the flow throttle element are selected according to a desired throttling effect of the flow throttle element. The throttling effect of the flow throttle element depends on the diameter ratios of magnet armature to flow throttle element and flow throttle element to valve housing. The axial extension of the flow throttle element is also important. By appropriately designing the flow throttle element, the throttling effect can be realized either by guiding the flow throttle element in the valve housing, with the flow passage being located between the inner wall and the magnet armature, or on the magnet armature, with the flow passage in this case being located between the outer wall and the valve housing.In order to determine the throttling effect of the flow throttling element, at least one of the distances and / or the axial extension of the flow throttling element are selected accordingly.

[0018] A further development of the invention provides that the distance between the first and the second end stop is less than or equal to a stroke of the solenoid valve, in particular of the main stage, and / or that the distance between the first and the second end stop is greater than or equal to a stroke of the pre-stage. The path that the flow throttle element can travel in the axial direction between the first end stop and the second end stop is set such that it is greater than the stroke of the pre-stage, but less than the stroke of the main stage. Stroke is understood to be the distance by which the closing element of the pre-stage or the main stage can be displaced. This ensures that the flow throttle element only becomes hydraulically effective when the pre-stage or its closing element is already in the corresponding open position.The pilot stage of the solenoid valve is therefore not affected by the flow restrictor, so the response time of the solenoid valve (switching time tan or tab) is not affected. Rather, the throttling effect of the flow restrictor only occurs when the pilot stage is open and the main stage, or its closing element, is to be moved into the open position. This is achieved by ensuring that the distance between the end stops is initially greater than or equal to the stroke of the pilot stage and simultaneously less than or equal to the stroke of the main stage of the solenoid valve.

[0019] The invention will be explained in more detail below with reference to the exemplary embodiments illustrated in the drawings, without limiting the invention. They show: Fig. 1 a side sectional view of a solenoid valve with a magnet armature and a valve element, each forming an end stop, wherein a flow throttle element is arranged between the end stops, and Fig. 2 a detailed sectional view of the solenoid valve in the area of ​​the flow restrictor element.

[0020] The Fig. 1 shows a section through a solenoid valve 1. The solenoid valve 1 has a valve housing 2 in which a magnet armature 3 is arranged so as to be axially displaceable. Fig. Figure 1 shows how the solenoid valve 1 with the valve housing 2 is arranged or fastened in a holder 4 of an external device. The solenoid valve 1 has a plurality of inlets 5 - although alternatively only a single inlet 5 can be provided - although only two of the inlets 5 are visible here. The flow to the solenoid valve 1 through the inlets 5 occurs in a radial direction. The flow out of the solenoid valve 1 through an outlet 6, on the other hand, is provided in an axial direction. The axial direction is to be understood as a longitudinal axis of the solenoid valve 1, which is indicated here by the line 7. In terms of flow, a filter element 8 is attached upstream of the inlets 5, which is also assigned to the solenoid valve 1.

[0021] The solenoid valve 1 is designed as a two-stage solenoid valve. It accordingly has a pre-stage 9 and a main stage 10. The pre-stage 9 is assigned a valve seat 11 and a closing element 12, whereas the main stage 10 is assigned a valve seat 13 and a closing element 14. The closing element 14 is part of a valve body 15, on which the valve seat 11 of the pre-stage 9 is also provided. The valve body 15 has a fluid channel 16 passing through it in the axial direction, through which a flow connection is established between the inlets 5 and the outlet 6 when the closing element 12 releases the valve seat 11. However, the fluid channel 16 has, at least in some regions, only a small diameter, so that only a small amount of fluid can flow through it per unit of time.

[0022] In order to fully open the solenoid valve 1, it is therefore also necessary for the closing element 14 to also release the valve seat 13. Typically, when the differential pressure between the inlets 5 and the outlet 6 is high, only the pre-stage 9 can be opened. Opening causes the differential pressure to drop. Once it has dropped sufficiently, the main stage 10 can also be opened by displacing the closing element 14 out of the valve seat 13. Both the displacement of the closing element 12 and the closing element 14 is brought about by a displacement of the magnet armature 3. For this purpose, the closing element 12 is attached directly to the magnet armature 3, so that a direct operative connection is established. The operative connection between the magnet armature 3 and the closing element 14 is established via an intermediate piece 17.The intermediate piece 17 is sleeve-shaped, at least in part, and at least partially surrounds a lower region 18 of the magnet armature 3. This surround firmly connects the intermediate piece 17 to the magnet armature 3. For example, the intermediate piece 17 is crimped onto the lower region 18.

[0023] In the in the Fig. In the closed position of the solenoid valve 1 shown in Figure 1, the magnet armature 3 is arranged to close the valve seats 11 and 13. This means that the closing element 12 sits sealingly in the valve seat 11 and the closing element 14 sits sealingly in the valve seat 13, so that there is no fluid connection between the inlets 5 and the outlet 6. In order to hold the magnet armature 3 in the closed position, a spring 19 is provided, which urges the magnet armature 3 into this position. The closed position is therefore an initial position of the solenoid valve 1, so that it represents a normally closed solenoid valve. In order to open the solenoid valve 1, the magnet armature 3 is moved towards an open position or release position. In this process, the closing element 12 is first moved out of the valve seat 1, so that a fluid connection is established via the fluid channel 16.The closing element 14 initially remains in the valve seat because a guide device 20 of the intermediate piece 17, via which an operative connection can be established between the magnet armature 3 and the closing element 14, is spaced so far in the axial direction from a counter surface 21 of the closing element 14 that the guide device 20 only comes into contact with the counter surface 21 when the magnet armature 3 is in a position in which the preliminary stage 9 is fully open. Only when the preliminary stage 9 is open and the magnet armature 3 is displaced further toward the open position can the main stage 10 also be opened by displacing the closing element 14 from the valve seat 13.

[0024] Above the magnet armature 3 there is a fluid chamber 22 and below it a fluid chamber 23. When the magnet armature 3 is displaced, fluid must be able to flow from the fluid chamber 22 into the fluid chamber 23 and vice versa in order to achieve pressure equalization. For this purpose, a flow path 24 is provided between the valve housing 2 and the magnet armature 3 or a valve element 25. In this case, the valve element 25 has the closing element 14 and the intermediate piece 17. The closing element 12, on the other hand, is assigned to a further valve element 26. Particularly when the solenoid valve 1 is in the depressurized state, pressure waves can arise when the main stage 10 opens and closes, which lead to disturbing noises. These noises arise when the fluid flows through the flow path 24, which has a small cross-section, in order to flow between the fluid chambers 22 and 23. The fluid is therefore greatly accelerated.If it now hits a hydraulic stop, high pressure occurs at this point and the annoying noise is created.

[0025] To prevent this, a flow throttle element 27 is assigned to the solenoid valve 1, which in the present embodiment is in the form of an annular disk. The flow throttle element 27 is arranged in the flow path 24 and is axially displaceable between a first stop 28 and a second end stop 29. In the embodiment presented here, the first end stop 28 is formed by the magnet armature 3, and the second end stop 29 is formed by the intermediate piece 17 or the valve element 25. The flow throttle element 27 is guided by the latter completely encompassing the lower region 18 of the magnet armature 3 in the circumferential direction. The first end stop 28 is in the form of an annular step 30 of the magnet armature 3. The annular step 30 is formed by a change in the diameter of the magnet armature 3 between the lower region 18 and an upper region 31. The upper region 31 therefore has a larger diameter than the lower region 18.The second end stop 29, on the other hand, is located on an end face 32 of the intermediate piece 17 or the valve element 25.

[0026] The flow throttle element 27 is designed such that a flow passage 33 is present between its outer wall and the valve housing 2. The fluid can flow through this flow passage 33, whereby the throttling effect of the flow throttle element 27 occurs simultaneously. In order to prevent the flow throttle element 27 from negatively influencing the switching time of the solenoid valve 1, the distance between the first end stop 28 and the second end stop 29 is selected such that it is greater than or equal to a stroke of the pre-stage 9. In such an embodiment, the flow throttle element 27 usually only comes into contact with the first end stop 28 or the second end stop 29 when the pre-stage 9 is already fully open. The throttling effect of the flow throttle element 27 is therefore only present for the main stage 10.Due to the axial displaceability of the flow throttle element 27, at the beginning of a displacement of the magnet armature 3 - until the preliminary stage 9 is fully opened when the solenoid valve 1 is opened or the main stage 10 is fully closed when the solenoid valve 1 is closed - this has no effect on a fluid flow between the fluid chambers 22 and 23, but rather enables an unhindered up or down movement of the magnet armature 3. The reaction time of the solenoid valve 1 is therefore not changed.

[0027] As the displacement of the magnet armature 3 continues, the flow throttle element 27 hits either the first stop 28 or the second stop 29, subsequently causing hydraulic throttling or damping. The point in time at which the flow throttle element 27 comes into contact with one of the end stops 28 and 29 can be determined by specifically attaching or pressing the intermediate piece 17 onto the magnet armature 3 at a predetermined distance. Of course, the end stops 28 and 29 can alternatively also be formed by separate elements, for example, by retaining rings applied to the magnet armature 3. However, the end stops 28 and 29 are preferably formed by the magnet armature 3 or the intermediate piece 17, because this allows for simple and cost-effective production of the solenoid valve 1 without additional parts (apart from the flow throttle element 27).During manufacture or assembly of the solenoid valve 1, the distance between the end stops 28 and 29 is achieved by appropriately selecting the axial extension of the intermediate piece 17. This is selected such that the required displacement of the flow restrictor element 27 is ensured after adjusting the stroke of the pre-stage 9.

[0028] The Fig. 2 shows a detailed sectional view of the solenoid valve 1 in the area of ​​the flow throttle element 27. The embodiment shown here corresponds to the one shown in the Fig. 1. In this respect, reference is made to the above explanations.

Claims

[1] Solenoid valve (1), comprising a magnet armature (3) arranged axially displaceably in a valve housing (2) and at least one valve element (25, 26) operatively connected to the magnet armature (3), wherein the valve element (25, 26) is displaceable by means of the magnet armature (3) to release or close at least one valve seat (11, 13) of the magnet valve (1), and wherein at least one flow path (24) is formed between the valve housing (2) and the magnet armature (3) and / or the valve element (25, 26), characterized by a flow throttle element (27) provided in the flow path (24), which is arranged to be axially displaceable between a first end stop (28) formed by the magnet armature (3) and a second end stop (29) formed by the valve element (25, 26). [2] Solenoid valve according to claim 1, characterized bythat the valve element (25,26) has at least one closing element (12,14) assigned to the valve seat (11,13), wherein in particular an intermediate piece (17) of the valve element (25,26) establishes an operative connection between the magnet armature (3) and the closing element (12,14). [3] Solenoid valve according to claim 2, characterized by that the valve element (25,26) has a plurality of closing elements (12,14), each closing element (12,14) being provided for releasing or closing a respective valve seat (11,13). [4] Solenoid valve according to claim 2 or 3, characterized by that one of the closing elements (12,14) is assigned to a preliminary stage (9) and another of the closing elements (12,14) is assigned to a main stage (10) of the solenoid valve (1). [5] Solenoid valve according to one of claims 2 to 4, characterized by that the intermediate piece (17) encompasses the magnet armature (3) at least in part and / or is fastened to it. [6] Solenoid valve according to one of the preceding claims, characterized by that the flow throttle element (27) is designed as an annular disc. [7] Solenoid valve according to one of the preceding claims, characterized by that the first end stop (28) is formed by an annular step (30) of the magnet armature (3) and / or the second end stop (29) is present on an end face (32) of the intermediate piece (17). [8] Solenoid valve according to one of the preceding claims, characterized by that the flow throttle element (27) has a flow passage (33) between its outer wall and the valve housing (2) and / or between its inner wall and the magnet armature (3). [9] Solenoid valve according to one of the preceding claims, characterized bythat the distance between the outer wall and the valve housing (2), the distance between the inner wall and the magnet armature (3) and / or an axial extension of the flow throttle element (27) are selected according to a desired throttling effect of the flow throttle element (27). [10] Solenoid valve according to one of the preceding claims, characterized by that the distance between the first and the second end stop (28,29) is less than or equal to a stroke of the solenoid valve (1), in particular of the main stage (10), and / or that the distance between the first and the second end stop (28,29) is greater than or equal to a stroke of the preliminary stage (9).

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