Check valve

Abstract

The invention relates to a check valve (10), in particular for controlling the flow direction in a pressure medium connection of a hydraulic unit of an electronically slip-controllable vehicle brake system. Known check valves (10) have a valve housing (12) with an inlet (16), an outlet (18) and an interposed control cross section (20) which is controlled by a closing element (24). What is proposed is a check valve (10) in which the inlet (16) and the outlet (18) are opposite one another and in which the closing element (24) is located inside a guide cage (30) in the valve housing (12). The guide cage (30) improves, inter alia, the flow resistance of the check valve (10).

Description

[0001] Disclosure of the invention

[0002] title

[0003] check valve

[0004] State of the art

[0005] The invention relates to a check valve, in particular for controlling the flow direction in a pressure medium connection of a hydraulic unit of an electronically controlled slip-controllable vehicle brake system, according to the features of the preamble of claim 1.

[0006] Such a check valve is known, for example, from DE 197 32 747 A1. This known check valve comprises a valve housing with an inlet at a first end, an outlet on the circumference, and a control cross-section arranged between the inlet and the outlet. A closing element is provided to control this control cross-section. This closing element is displaceably accommodated directly inside the valve housing and can be actuated by the pressure medium against the force of a return spring.

[0007] The disadvantage of this known check valve is that when the closing element is actuated, the associated return spring is compressed, which reduces the distance between the individual spring coils of this return spring and thus reduces the area between the spring coils through which the pressure medium flows. With increasing spring stroke or with increasing differential pressure between the pressure at the inlet and the pressure at the outlet, the flow resistance of this known check valve increases further.

[0008] Advantages of the invention

[0009] A check valve according to the features of claim 1 has the advantage that the spring compressed by the stroke of the closing element has no influence on the flow resistance of the return element.

[0010] This advantage is achieved in a check valve according to the invention in that the inlet and the outlet are opposite each other and that the closing element is arranged within a guide cage in the interior of the valve housing.

[0011] Further advantages or advantageous developments of the invention emerge from the subclaims and / or from the following description.

[0012] By designing the guide cage according to the features claimed in claims 2 to 6, a maximum volume flow through the check valve as well as a pressure drop between inlet and outlet can be determined and maintained independently of the spring stroke.

[0013] Furthermore, the closing element is guided axially and radially by the guide cage, thus preventing vibrations of the closing element and associated operating noise. The user is free to use the invention with a check valve equipped with or without an elastic return element.

[0014] With a guide cage, the maximum stroke of the closing element can be specified and, in addition, a guide cage according to the invention offers a simple possibility for filtering the pressure medium flowing through the check valve, so that contamination can be retained and damage or functional limitations to components provided downstream of the check valve can be avoided.

[0015] To secure a structural unit consisting of a guide cage, a closing element, and, if applicable, a return element in a valve housing, radial projections can be provided on the outer circumference of the guide cage. These projections are arranged in areas where the cross-section of the guide cage exhibits particularly high elasticity, allowing a radial holding or preload force between the guide cage and the valve housing to be adjusted as needed without undesirably affecting the guidance of the closing element and / or any return element.

[0016] Drawing An embodiment of the invention is shown in the drawing and is explained in detail in the following description.

[0017] The drawing comprises a total of four figures, in which corresponding components are provided with identical reference symbols. The figures show the following in detail:

[0018] Fig. 1a, 1b, 1c: a first embodiment of a check valve according to the invention in longitudinal section and in closed, partially open and fully open position;

[0019] Fig. 2a, 2b: a second embodiment of a check valve according to the invention in longitudinal section in closed and fully open position;

[0020] Fig. 3a; 3b, 3c: a guide cage on which the invention is based in two perspective views from obliquely above and from obliquely below, as well as an advantageous further development of a guide cage and

[0021] Fig. 4a, 4b: the guide cage in plan view as a single part and as a detail in its installed state in a

[0022] Valve housing.

[0023] Description of the embodiment

[0024] Figure 1 shows a first embodiment of a check valve (10) according to the invention in longitudinal section in a total of three different valve positions. In this context, Figure 1a shows the check valve (10) in a blocking position, Figure 1b in a partial stroke position, and Figure 1c in a full stroke position. In the partial stroke position and the full stroke position, the check valve (10) is open and is flowed through by pressure medium, preferably hydraulic pressure medium.

[0025] The check valve (10) comprises a valve housing (12) with a hollow interior (14), an inlet (16) which opens into this interior (14) at an upper end-face boundary, and an outlet (18) which opens out of the interior (14) at a lower end-face boundary. The inlet (16) and outlet (18) are located coaxially opposite one another. The opening cross-section of the inlet (16) into the interior (14) forms a control cross-section (20) of the check valve (10) and is enclosed by a valve seat (22). The latter is controlled by a closing element (24), which is designed, for example, as a ball and is acted upon by an elastic return element (26). The return element (26) is, for example, a spiral spring which acts on the closing element (24) against a flow direction from the inlet (16) to the outlet (18).

[0026] The closing element (24) and the return element (26) are accommodated in a guide cage (30). This guide cage (30) is a component, preferably made of plastic using an injection molding process, which is inserted into the interior (14) of the valve housing (12) between the end and peripheral boundaries and is held therein under radial preload.

[0027] This guide cage (30) has a first end (32) on the inlet side and a second end (34) on the outlet side. The two ends (32; 34) are rigidly connected to one another by a preferably odd number of longitudinal struts (36). These longitudinal struts (36) are distributed around the circumference of the guide cage (30) in such a way that pressure medium passage openings (38) are formed between them.

[0028] The first end (32) of the guide cage (30) is shaped into a circular ring whose inner dimensions are larger than the outer dimensions of the closing element (24). This closing element (24), driven by the mechanical force of the elastic return element (26), penetrates the ring opening and interacts with the valve seat (22) formed outside the guide cage (30) on the valve housing (12). In the blocking position according to Fig. 1a, the closing element (24) rests against the valve seat (22) and seals it.

[0029] In contrast to the first embodiment, the second end (34) of the guide cage (30) is designed as a closed base plate which completely covers the cross section of the guide cage (30) with the exception of outer circumferential segments.

[0030] Several support feet (40) extend from this base plate in the longitudinal and axial directions of the guide cage (30). These feet are spaced apart along the circumference of the guide cage (30). With its support feet (40), the guide cage (30) rests on the lower end boundary of the interior (14) of the valve housing (12), thus creating an axial gap (42) between this lower end boundary and the base plate, through which the pressure medium can flow to the outlet (18).

[0031] In the partial stroke position according to Fig. 1 b, the closing element (24) is subjected to the mechanical force of the return element (26) and a compressive force directed in the opposite direction, which results from an existing pressure difference between the pressure of the pressure medium at the inlet (16) and the pressure of the pressure medium at the outlet (18). The compressive force is so great that the closing element (24) is lifted from the valve seat (22), the elastic return element (26) is compressed by the closing element (24), and the control cross-section (20) of the check valve (10) is released. Pressure medium consequently flows through the inlet (16) into the interior space (14) of the valve housing (12).

[0032] The flow path of this pressure medium through the check valve is illustrated in Fig. 1 b using a directional arrow R. Incoming pressure medium first passes through the control cross-section (20) and between the outer contour of the closing element (24) and the inner contour of the ring at the first end (32) into the interior of the guide cage (30). From there, the pressure medium flows through the pressure medium passage openings (38), along the outer circumference of the guide cage (30) to the area of ​​the guide cage (30) with the support feet (40). Between the support feet (40), the pressure medium then flows on to the outlet (18) at the lower end boundary of the interior space (14). The flow path therefore does not run through the elastic return element (26) or between its spring coils, so that the return element (16) has no throttling influence on the pressure medium flow.

[0033] The same applies to the full stroke position of the check valve (10) shown in Fig. 1c, which differs from the partial stroke position according to Fig. 1b only in that the closing element (24) is further away from the valve seat (22) due to an effectively greater pressure difference between the inlet pressure and the outlet pressure and consequently the axial distances between the individual spring coils have become smaller due to the correspondingly greater compression of the return element (26).

[0034] The second embodiment of a check valve (10) according to Figures 2a and 2b differs from the first embodiment explained in that it is designed without an elastic return element (26) and the closing element (24) is thus actuated only by the prevailing flow forces.

[0035] This closing element (24) is accommodated in a guide cage (30), in which both the first end (32) facing the inlet (16) and the second end (34) facing the outlet (18) are each designed as a ring. However, while the ring at the first end (32) of the guide cage (30) still has internal dimensions that are larger than the external dimensions of the closing element (24), this is not the case for the ring at the second end (34). Its internal dimensions are smaller than the external dimensions of the closing element (24), as a result of which this closing element (24) mechanically strikes the second end (34) and is thus held inside the guide cage (30). By matching the internal dimensions of the ring at the second end (34) of the guide cage (30) to the external dimensions of the closing element (24), a maximum stroke of this closing element (24) can be specified structurally.

[0036] In this second embodiment, as mentioned, the closing element (24) is actuated solely as a function of the prevailing pressure gradient between the pressure at the inlet (16) and the pressure at the outlet (18). If this pressure gradient is negative, i.e., the pressure at the outlet (18) is higher than at the inlet (16), the closing element (24) is subjected to the effective flow forces against the valve seat (22), thus closing the check valve (10) (Fig. 2a).

[0037] Conversely, the check valve (10) opens when there is a positive pressure gradient. The closing element (24) is then moved by the flowing pressure medium away from the control cross-section (20) towards the second end (34) of the guide cage (30) until it strikes the ring of this second end (34) and closes the ring cross-section. As indicated by the directional arrow R, in this second exemplary embodiment the pressure medium does not flow through the interior of the guide cage (30), but rather, after initially penetrating the interior of the guide cage (30) through the first end (32), flows back out through the pressure medium passage openings (38) and from there further along the outer circumference of the guide cage (30) to the area with the support feet (40) and, in the continuation between these support feet (40), to the outlet (18) of the check valve (10).

[0038] Figures 3a and 3b of the drawing show two perspective views of a guide cage (30) according to embodiment 1 as an individual part.

[0039] As mentioned, this guide cage (30) comprises a first end (32) facing the control cross-section or the inlet (16) of this check valve (10), which is designed as a ring, as well as a second end (34) arranged opposite thereto, facing the outlet (18), which forms a closed base plate. The ring at the first end (32) is rigidly connected to the base plate at the second end (34) of the guide cage (30) by, for example, three longitudinal struts (36). These longitudinal struts (36) are arranged distributed over the circumference of the guide cage (30) and each delimits one of a total of several circumferential pressure medium passage openings (38) between them.

[0040] The longitudinal struts (36) are connected to the ring within the ring at the first end (32) of the guide cage (30), so that this ring has larger cross-sectional dimensions at the connecting sections (44) than in the sections located between the longitudinal struts (36). In other words, the ring cross-section has recesses (46) in the sections between the longitudinal struts (36) and, due to the different cross-sectional dimensions, is divided in the circumferential direction into sections of high elasticity and, in contrast, of lower elasticity. The sections of different elasticity alternate one another in the circumferential direction.

[0041] Furthermore, a plurality of, for example, three radial projections (48) are formed on the outer circumference of the first end (329) of the guide cage (30) and project outwards. These radial projections (48) can be strip-shaped as shown or alternatively, for example, knob-shaped. The radial projections (48) are arranged in a region of high elasticity of the ring, preferably in the circumferential direction in the middle between each two of the longitudinal struts (36).

[0042] Opposite the first end (32), the longitudinal struts (36) merge into the base plate at the second end (34) of the guide cage (30). This base plate borders on the circumference of guide surfaces (50) formed on the inner sides of the longitudinal struts (36) in order to guide the closing element (24) and, if appropriate, a return element (26) of the check valve (10) axially and radially. The longitudinal struts (36) thus protrude radially outwards from the second end (34) of the guide cage (30) with their respective strut cross-sections. The longitudinal struts (36) each have, for example, the cross-sectional shape of a circular ring segment with one offset in its outer diameter.

[0043] Support feet (40) are formed on the base plate, which protrude from the guide cage (30) in the longitudinal direction of the check valve (10). These support feet (40) are each arranged as an axial extension of one of the longitudinal struts (36) and, by way of example, continue the strut cross-sections explained above.

[0044] In an advantageous development of the invention shown in Fig. 3c, the guide cage is manufactured by overmolding a cylindrical filter fabric (52), so that the pressure medium passage openings (38) of a guide cage (30) are ultimately covered by this filter fabric (52). With a guide cage (30) designed in this way, components arranged downstream of this guide cage (30), for example, components for pressure medium guidance and / or pressure control, can be protected from dirt, particles, and potential malfunctions.

[0045] Figure 4 shows a top view of a guide cage (30) on which the invention is based. Clearly visible are the connecting sections (44) at which the ring of the first end (32) of the guide cage (30) is connected to the longitudinal struts (36) and consequently has a large or wide annular cross-section, the areas of the recesses (46) of the ring, which extend between the longitudinal struts (36) and form a small or narrow annular cross-section, and the outwardly projecting radial projections (48) on the ring, which are opposite the recesses (46). The radial projections (48) serve to force-fit a structural unit comprising the guide cage (30), the closing element (24), and optionally the return element (26) in the interior (14) of the valve housing (12) by pressing in. For this purpose, the radial projections (48) are arranged in those areas where the ring has a small or narrow annular cross-section and thus a high degree of elasticity.The reason for this placement of the radial projections (48) is that the guidance of the closing element (24) and the return element (26) on the guide surfaces (50) of the longitudinal webs (36) can be decoupled from any deformation of the guide cage (30) as a result of the pressing-in process and thus the intended.

[0046] The guiding properties of the locking element (24) and / or the return element (26) remain unaffected. Furthermore, the pressing or holding forces can be adjusted as required by selecting the elasticity of the narrow ring cross-section.

[0047] Of course, changes or advantageous developments of the described embodiments are possible, which do not depart from the scope of protection specified by the claims.

Claims

Claims 1. A check valve (10), in particular for controlling the flow direction in a pressure medium connection of a hydraulic unit of an electronically slip-controllable vehicle brake system, comprising a valve housing (12) forming an inlet (16) and an outlet (18), a control cross-section (20) arranged between the inlet (16) and the outlet (18), and a closing element (24) which controls the control cross-section (20) and is displaceably received in an interior space (14) of the valve housing (12), characterized in that the inlet (16) of the check valve (10) is opposite the outlet (18), and in that the closing element (24) is arranged within a guide cage (30) in the interior space (14) of the valve housing (12).

2. Check valve according to claim 1, characterized in that a first end (32) of the guide cage (30) facing the inlet (16) forms a closed ring with internal dimensions which are larger than the external dimensions of the closing element (24), that the closing element (24) is held in the interior of the guide cage (30) by a second end (34) axially opposite the first end (32), and that the first end (32) is connected to the second end (34) of the guide cage (30) by a plurality of longitudinal webs (36) which are arranged along a circumference of the guide cage (30) at a mutual distance from one another in such a way that a pressure medium passage opening (38) is formed between each two longitudinal webs (36).

3. Check valve according to claim 2, characterized in that that the second end of the guide cage (34) is a closed bottom and serves as an axial support for an elastic return element (26) which actuates the closing element (24) or that the second end (34) of the guide cage (30) forms a ring whose inner dimensions are smaller than the outer dimensions of the closing element (24).

4. Check valve according to claim 1 or 2, characterized in that the guide cage (30) is equipped with a plurality of support feet (40) which project in the axial direction from the second end (34) of the guide cage (30) and which set an axial gap (42) between the second end (34) of the guide cage (30) and an end-side boundary of an interior space (14) of the valve housing (12) on which the outlet (18) of the check valve (10) is formed.

5. Check valve according to claim 4, characterized in that the support feet (40) are arranged in axial extension of the longitudinal webs (36) of the guide cage (30).

6. Check valve according to one of claims 2 to 4, characterized in that the ring has at the first end (32) recesses (46) which are open towards the interior of the guide cage (30) and which, viewed in the circumferential direction of the guide cage (30), are arranged in an axial extension of the pressure medium passage openings (38).

7. Check valve according to one of claims 1 to 4, characterized in that the inner sides of the longitudinal webs (36) form guide surfaces (50) by means of which the closing element (24) is guided radially and axially in the guide cage (30).

8. Check valve according to one of claims 2 to 7, characterized in that that the pressure medium passage openings (38) of the guide cage (30) are covered by a filter fabric (52).

9. Check valve according to one of claims 1 to 8, characterized in that a plurality of radial projections (48) are formed on the outer circumference of the first end (32) of the guide cage (30), which hold the guide cage (30) under a radial prestress in the interior of the valve housing (12).

10. Check valve according to claim 9, characterized in that the radial projections (48) are opposite the recesses (46) of the ring at the first end (32) of the guide cage (30).

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