Solenoid valve

Abstract

The invention relates to a solenoid valve (10), in particular for controlling a pressure medium connection between a main brake cylinder and a wheel brake of an electronically slip-controllable vehicle brake system. Known solenoid valves (10) comprise a solenoid coil (20) which encloses a valve housing, a tappet (34) which is displaceably arranged in the valve housing, a valve body (44) with a control cross-section (48) between a first valve connection (50) and a second valve connection (52), a closing member (42) which is coupled to the tappet (34) and controls the control cross-section (48), and an armature (38) for actuating the tappet (34). According to the invention, the valve housing has a multi-part design and comprises a valve insert (22) which guides the tappet (34) and a carrier sleeve (24) which receives the valve body (44). As a result of their structural design, the valve insert (22) and carrier sleeve (24) can be produced by means of forming technology and thus cost-effectively with high component quality.

Description

[0001] Disclosure of the invention

[0002] title

[0003] solenoid valve

[0004] State of the art

[0005] The invention relates to a solenoid valve, in particular for controlling a pressure medium connection between a master brake cylinder and a wheel brake of an electronically slip-controlled vehicle brake system according to the features of the preamble of claim 1.

[0006] Such a solenoid valve is already known, for example, from DE 10 2019 210 284 A1.

[0007] This solenoid valve is used, for example, in a hydraulic unit of a power brake system to control a pressure connection between the master brake cylinder and a wheel brake. During normal operation of the power brake system, this pressure connection is closed by the solenoid valve. In the event of a system failure, the pressure connection is opened, enabling a driver to manually actuate the master brake cylinder to build up brake pressure in an assigned wheel brake and decelerate the vehicle. In technical circles, this functionality is known as a hydraulic fallback system.

[0008] In this context, the requirements for the solenoid valve are to shut off the aforementioned pressure medium connection when closed, i.e. during normal operation of the power brake system, and to reliably seal it against high pressure in the master brake cylinder if necessary.

[0009] On the other hand, if a fault occurs, the solenoid valve must be able to open against any existing system pressure.

[0010] A solenoid valve underlying the invention is constructed from a number of components, which, due to their geometric complexity, have traditionally been manufactured using machining. This process is time-consuming and costly, resulting in, among other things, a high amount of machined material. Furthermore, larger component tolerances result. With the increasing prevalence of power brake systems on the market, the need for cost-effective and reliable solenoid valves is also growing.

[0011] Advantages of the invention

[0012] Solenoid valves according to the features of claim 1 comprise valve components which can be produced by forming and can thus be provided in sufficient quantities at low cost and with good quality and low component tolerance.

[0013] According to the invention, the valve housing is constructed in several parts and consists of a valve insert and a support sleeve inserted therein. The valve insert is manufactured using cold-forming technology, and the support sleeve is manufactured using a deep-drawing process.

[0014] The axial or radial grooves required inside the solenoid valve to create a flow contour can thus be created without drilling or milling. By pressing a valve body with a control cross-section into the carrier sleeve and pressing this carrier sleeve into the valve insert equipped with a tappet and a return element, the valve forces and valve characteristics can be adapted or individually adjusted to the specific requirements of the individual case. The invention avoids a rigid assembly consisting of a caulking contour and an interference fit when fixing the solenoid valve to a hydraulic block of a hydraulic unit, thus preventing stresses caused by component tolerances and / or different expansion properties of the affected materials of the valve components. The valve body is attached to the carrier sleeve via a press fit, pressure-tight and space-saving.

[0015] Further advantages or advantageous developments of the invention emerge from the subclaims or from the following description.

[0016] Drawing: An exemplary embodiment of the invention is illustrated in the drawing and explained in detail in the following description. The drawing comprises a single figure, which shows a longitudinal section of a hydraulic assembly of a solenoid valve underlying the invention, anchored to a hydraulic block of a hydraulic unit.

[0017] Description

[0018] The single figure shows a longitudinal section of a hydraulic assembly (12) of a solenoid valve (10) underlying the invention. This hydraulic assembly (12) is mounted in an associated valve receptacle (14) formed on an outer surface of a hydraulic block (16) of a hydraulic unit of an electronically controlled power brake system. Only a section of the hydraulic block (16) is shown in the figure.

[0019] The hydraulic assembly (12) of the solenoid valve (10) extends partially into the valve receptacle (14) and further comprises a second valve section that protrudes outward relative to the outer surface of the hydraulic block (16). This protruding valve section forms a so-called valve dome (18), on which a solenoid coil (20) is arranged such that the valve dome (18) is enclosed by this solenoid coil (20). The figure shows a simplified schematic representation of the solenoid coil (18).

[0020] The hydraulic assembly (12) of the solenoid valve (10) consists, among other things, of a valve housing which, according to the invention, is designed in several parts and comprises a valve insert (22) and a carrier sleeve (24) inserted therein.

[0021] The valve insert (22) is hollow-cylindrical in design and has a continuous cylindrical opening (26). On its outer circumference, the valve insert (22) is provided with a radially outwardly projecting flange (28), with which the valve insert (22) rests flush against an associated shoulder (30) of the valve receptacle (14). The valve insert (22) is caulked to the hydraulic block (16) via this flange (28). During a caulking process, material from the wall of the valve receptacle (14) is plastically deformed radially inward such that it covers, at least in segments, the annular surface of the flange (26) facing the valve receptacle opening. In the direction of a longitudinal axis L of the valve insert (22), the flange (28) is stepped several times in its outer diameter from the inside outward.

[0022] As mentioned, the valve insert (22) has a continuous cylinder opening (26). The latter is stepped once in its inner diameter, with a first section of this cylinder opening (26) having a larger inner diameter located within the hydraulic block (16), while a second section of the cylinder opening (26) having a smaller inner diameter faces outwards. The carrier sleeve (24) is pressed into the opening area of ​​the first section of the cylinder opening (26).

[0023] The valve insert (22) is free of undercuts and can therefore be produced cost-effectively and in large quantities with good quality using forming technology. A cold forming process is particularly suitable for this purpose.

[0024] The support sleeve (24) is divided into two sleeve sections (24a, 24b) of different sizes. A first sleeve section (24a), with a smaller outer diameter, is pressed into the cylinder opening (26) of the valve insert (22) in a pressure-tight manner. A second, larger-diameter sleeve section (24b) protrudes from the valve insert (22) in the direction of the longitudinal axis L and is pressed into an associated bore of the valve seat (14) inside the hydraulic block (16).

[0025] The two sleeve sections (24a, 24b) of the support sleeve (24) merge into one another at a right-angled step (32). The support sleeve (24) can be pressed into the first area of ​​the valve insert (22) until the step (32) is flush with an annular surface at one end of the valve insert (22). In this way, the press-in dimension of the support sleeve (24) into the valve insert (22) can be freely selected depending on the tolerance and, if necessary, adjusted mechanically during valve assembly.

[0026] The carrier sleeve (24) is also produced cost-effectively using forming technology; due to its thin walls, a deep-drawing process is preferred.

[0027] A fully cylindrical tappet (34) is accommodated in the first section of the cylinder opening (26) of the valve insert (22), which has a smaller inner diameter, and is guided for axial displacement against the force of an elastic return element (36) in the form of a spiral spring. A first tappet end is designed as a flat end face, with which this tappet (34) protrudes from the cylinder opening (26) of the valve insert (22) by a working gap A. An armature (38) of the solenoid valve (10) rests on the end face of the tappet (34). The armature is accommodated for axial displacement inside a hollow valve capsule (40). This valve capsule (40) has a dome shape and is fastened by its open end to the outer circumference of the valve insert (22). A circumferential welded joint is preferably provided as the connection between the valve capsule (40) and the valve insert (22).

[0028] The end of the plunger (34) opposite the flat end face is designed as a pin-shaped, conically tapered closing member (42) which is formed at its free end, for example, as a spherical segment.

[0029] A transition from the closing member (42) to the plunger (34) forms a radially circumferential support surface for the elastic return element (36). An opposite end of this return element (36) bears against a valve body (44), which is pressed into the interior of the smaller-diameter first sleeve section (24a) of the support sleeve (24) in a pressure-tight manner.

[0030] This valve body (44) is hat-shaped and consists of a cylindrical shaft (44a) and a base (44b), which closes the shaft (44a) at its end facing the return element (36). The base (44b) is formed into a valve seat (46) in the shape of an inner cone, at the base of which a through-bore opens. The cross-section of this through-bore forms the control cross-section (48) of the solenoid valve (10), which is controlled by the closing element (42) of the tappet (34).

[0031] In the illustrated, non-energized basic position of the solenoid valve (10), the closing member (42) is lifted from the valve seat (46) by the mechanical force of the return element (36), thus opening the control cross-section (48). If the solenoid coil (20) is energized, the mechanical force of the return element (36) is counteracted by a magnetic force of a magnetic circuit, so that the closing member (42) closes the control cross-section (48), thus interrupting a pressure medium connection between a first valve connection (50) and a second valve connection (52) of the solenoid valve (10).

[0032] The first valve connection (50) is arranged on the circumference of the solenoid valve (10) in the transition region between the end of the valve insert (22) and the protruding second sleeve section (24b) of the support sleeve (24). Pressure medium which flows to the solenoid valve (10) via this first valve connection (50) is cleaned of impurities by a fitted filter. For this purpose, the filter comprises a ring filter (54) carried by a filter frame and is pressed with its tappet-side end onto a filter seat (56) on the valve insert (22). The opposite end of this filter, facing away from the tappet, forms a corresponding press and sealing connection with the circumference of the second sleeve section (24b) of the support sleeve (24) protruding from the valve insert (22).Incoming pressure medium flows through flow channels formed inside the solenoid valve (10) between the inner circumference of the valve insert (22) and the outer circumference of the pressed-in first part of the support sleeve (24) to an installation space for the return element (36) or the spiral spring, and from there to the control cross-section (48). When the control cross-section (48) is open, the pressure medium flows further into the interior of the valve body (44) and from there into the second, larger-diameter sleeve section (24b) of the support sleeve (24) to the second valve connection (52).

[0033] The latter is formed at the mouth point of the larger diameter sleeve section (24b) of the support sleeve (24) into the hydraulic block (16) and comprises a filter pressed circumferentially into the support sleeve (24) and consisting of an annular filter housing and a flat filter (58) made of close-meshed filter fabric covering the annular opening.

[0034] Both valve ports (50, 52) are therefore provided with filters (54; 58), since the solenoid valve (10) is designed to accept flow in both directions. A second flow direction is opposite to the flow direction described above. The two filter devices (54; 58) at the two valve ports (50; 52) accordingly keep the interior of the solenoid valve (10) free of contaminants that could impair the sealing function of the closing element (42) or the freedom of movement of the movable valve components, or that could cause wear on the movable components over the operating life of the solenoid valve (10).

[0035] Of course, changes to the described embodiment of a solenoid valve are conceivable without thereby departing from the scope of protection determined by the claims.

Claims

Claims 1. Solenoid valve (10), in particular for controlling a pressure medium connection between a master brake cylinder and a wheel brake of an electronically slip-controllable vehicle braking system, comprising a valve housing in which a tappet (34) is slidably received counter to the force of an elastic return element (36), a valve body (44) with a control cross-section (48) surrounded by a valve seat (46), which is arranged between a first valve connection (50) and a second valve connection (52) of the solenoid valve (10), a closing member (42) which is coupled to the tappet (34) for controlling the control cross-section (48) and with a displaceably arranged armature (38) for actuating the tappet (34), characterized in that the valve housing is designed in several parts and comprises a valve insert (22) guiding the tappet (34) and a carrier sleeve (24) receiving the valve body (44) and inserted into the valve insert (22).

2. Solenoid valve according to claim 1, characterized in that the carrier sleeve (24) can be produced in a deep-drawing process and has sleeve sections (24a; 24b) of different external dimensions, wherein the carrier sleeve (24) with the first sleeve section (24a), which has smaller external dimensions than the second sleeve section (24b), is pressed into the valve insert (22), wherein the valve body (44) is received in the first sleeve section (24a) in a pressure-tight manner and wherein the second sleeve section (24b) protrudes from the valve insert (22) in the direction of a longitudinal axis L and forms one of the valve connections (52).

3. Solenoid valve according to claim 1 or 2, characterized in that the second sleeve portion (24b) is designed to be pressed into an associated bore of a valve receptacle (14) of a hydraulic block (16) of an electronically slip-controllable vehicle brake system.

4. Solenoid valve according to claim 3, characterized in that the valve insert (22) is produced in a forming process, in particular by cold forming, and has a radially projecting flange (28) with which the solenoid valve (10) is fastened, in particular caulked, to the hydraulic block (16) of a hydraulic unit of an electronically slip-controllable power brake system.

5. Solenoid valve according to one of claims 1 to 4, characterized in that a filter (54; 58) is each assigned to the valve connections (50, 52), the first filter (54) being pressed with one end onto the circumference of the valve insert (22) and with the other end onto the circumference of the second sleeve section (24b) in a sealing manner, and the second filter (58) being pressed with its circumference into the interior of the second sleeve section (24b) of the carrier sleeve (24).

6. Solenoid valve according to one of claims 1 to 5, characterized in that the first filter comprises a cylindrical ring filter (54) and the second filter comprises a flat filter (58).

7. Solenoid valve according to one of claims 1 to 6, characterized in that a transition from the first sleeve section (24a) to the second sleeve section (24b) of the carrier sleeve (24) forms a step (32) which faces an annular surface on the end face of the valve insert (22).

8. Solenoid valve according to one of claims 1 to 7, characterized in that the valve body (44) is pot-shaped and has a hollow shaft (44a) and a bottom (44b) at one end of this shaft (44a), on which the valve seat (46) and the control cross-section (48) are formed.

9. Solenoid valve according to one of claims 8, characterized in that the valve body (44) is pressed into the first sleeve portion (24a) of the carrier element (24).

10. Solenoid valve according to one of claims 1 to 9, characterized in that a spiral spring forms the return element (36) for the tappet (34), which is supported with one of its ends on the bottom (44b) of the valve body (44)

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