solenoid valve

Abstract

This invention relates to a solenoid valve (10), which is particularly used for controlling the pressure medium connection between the master brake cylinder and the wheel brakes of an electronic anti-skid control vehicle braking system. A known solenoid valve (10) includes an electromagnetic coil (20) surrounding a valve housing, a tappet (34) slidably arranged in the valve housing, a valve body (44) having a control cross section (48) located between a first valve port (50) and a second valve port (52), a closure (42) coupled to the tappet (34) and controlling the control cross section (48), and an armature (38) for actuating the tappet (34). According to the invention, the valve housing is a multi-piece structure and includes a valve insert (22) that guides the tappet (34) and a support sleeve (24) that accommodates the valve body (44). By designing the structure of the valve insert (22) and the support sleeve (24), the valve insert and the support sleeve can be manufactured using forming techniques, thereby reducing costs while maintaining high component quality.

Description

Technical Field

[0001] The present invention relates to a solenoid valve, particularly a solenoid valve for controlling the pressure medium connection between the master brake cylinder and the wheel brakes of an electronic anti-skid control vehicle braking system, the solenoid valve having the features of the preamble of claim 1. Background Technology

[0002] For example, such a solenoid valve has been disclosed in document DE 10 2019 210 284 A1.

[0003] This solenoid valve is used, for example, in the hydraulic unit of an external braking system to control the pressure medium connection between the master brake cylinder and the wheel brakes. During normal operation of the external braking system, this pressure medium connection is closed by the solenoid valve; in the event of a system failure, the connection is opened so that the driver can manually operate the master brake cylinder to build braking pressure in the corresponding wheel brakes and decelerate the vehicle. In the professional field, this function is known as the concept of a "hydraulic backup layer (Rückfallebene)".

[0004] In this context, the requirements for the solenoid valve are that, in the closed state—that is, during normal operation of the external braking system—it disconnects the aforementioned pressure medium connection and, if necessary, reliably seals against any high pressure that may exist in the master brake cylinder. On the other hand, in the event of a malfunction, the solenoid valve must be able to open over any potential system pressure.

[0005] The solenoid valve upon which this invention is based consists of multiple components, most of which have been manufactured to date through machining due to their complex geometry. This method is time-consuming, expensive, and generates a large amount of shavings. Furthermore, it introduces significant component tolerances. With the increasing prevalence of external braking systems in the market, the demand for cost-effective and reliable solenoid valves is also growing. Summary of the Invention

[0006] The solenoid valve according to claim 1 comprises valve components that can be manufactured using forming techniques, thus enabling the provision of a sufficient number of components at low cost and with good quality and small component tolerances.

[0007] Therefore, according to the present invention, the valve body is a multi-piece structure, consisting of a valve insert and a support sleeve inserted therein. The valve insert can be manufactured by cold forging technology, while the support sleeve is manufactured by deep drawing process.

[0008] Therefore, the axial or radial grooves required to form the flow profile inside the solenoid valve can be achieved without drilling or milling. By pressing the valve body with a control cross-section into the carrier sleeve in a stroke-monitoring manner, and then pressing the carrier sleeve into the valve insert equipped with a push rod and a reset element, the valve force or valve characteristics can be adjusted or individually set according to specific requirements. In this invention, the rigid connection structure of flared profile and press fit when fixing the solenoid valve to the hydraulic block of the hydraulic unit is avoided, thus preventing stress caused by component tolerances and / or different expansion characteristics of valve component materials. The valve body is fixed to the carrier sleeve in a space-saving manner by press fit for pressure medium sealing.

[0009] Other advantages or advantageous improvements of the invention are derived from the dependent claims or from the following description. Attached Figure Description

[0010] An embodiment of the invention is illustrated in the accompanying drawings, which are described in detail below. The drawings contain a unique illustration showing, in longitudinal sectional view, the structure of the hydraulic assembly of the solenoid valve, on which the invention is based, anchored to a hydraulic block of a hydraulic unit. Detailed Implementation

[0011] The only accompanying drawing shows, in longitudinal sectional view, the hydraulic assembly (12) of the solenoid valve (10) upon which the invention is based. This hydraulic assembly (12) is fixed in a corresponding valve housing (14), which is constructed on the outer surface of the hydraulic block (16) of the hydraulic unit of the electronic anti-slip control external force braking system. Only a portion of the hydraulic block (16) is shown in the figure.

[0012] The hydraulic assembly (12) of the solenoid valve (10) extends partially into the valve housing (14) and also has a second valve section extending outward relative to the outer surface of the hydraulic block (16). This extended valve section forms a so-called valve cap (18), on which a solenoid coil (20) is arranged such that the valve cap (18) is surrounded by the solenoid coil (20). The solenoid coil (20) is schematically shown in a simplified manner in the figure.

[0013] The hydraulic assembly (12) of the solenoid valve (10) also includes a valve housing, which is a multi-piece structure according to the invention and includes a valve insert (22) and a load-bearing sleeve (24) inserted therein.

[0014] The valve insert (22) is constructed in a hollow cylindrical shape and has a through cylindrical opening (26). A radially outwardly protruding flange (28) is constructed on the outer periphery of the valve insert (22), and the valve insert (22) rests against the corresponding shoulder (30) of the valve receiving portion (14) by means of the flange. The valve insert (22) is riveted to the hydraulic block (16) through the flange (28) by means of the material of the wall of the valve receiving portion (14) undergoing radial inward plastic deformation during the riveting process, so that it at least partially covers the annular surface of the flange (28) facing the opening of the valve receiving portion. Along the longitudinal axis L of the valve insert (22), the diameter of the flange (28) is stepped from the inside to the outside.

[0015] As described above, the valve insert (22) has a through cylindrical opening (26). The latter has a stepped inner diameter, with the larger first section located within the hydraulic block (16), while the smaller second section opens outward. The support sleeve (24) is pressed into the opening region of the first section of the cylindrical opening (26).

[0016] The valve insert (22) has no undercut, so it can be manufactured at low cost, in large quantities and with high quality using forming techniques. Cold forging is particularly suitable for this.

[0017] The bearing sleeve (24) is divided into two sleeve sections (24a, 24b) of different sizes. The bearing sleeve (24) with its smaller diameter first sleeve section (24a) is pressed into the cylindrical opening (26) of the valve insert (22) to achieve a pressure medium seal. The larger diameter second sleeve section (24b) extends from the valve insert (22) along the longitudinal axis L and is pressed into the corresponding orifice of the valve receiving part (14) inside the hydraulic block (16).

[0018] The two sleeve sections (24a, 24b) of the bearing sleeve (24) transition into each other at a right-angle step (32). The bearing sleeve (24) can be pressed into the first section of the valve insert (22) until its step (32) rests flat against the annular surface at the front end of the valve insert (22). In this way, the amount of pressing of the bearing sleeve (24) into the valve insert (22) can be freely selected according to tolerances and can be set by machine during valve assembly.

[0019] The bearing sleeve (24) is also manufactured inexpensively using forming technology, and due to its thin wall thickness, it is preferably suitable for deep drawing.

[0020] A solid cylindrical push rod (34) is accommodated in the first section of the cylindrical opening (26) of the valve insert (22) with a smaller inner diameter, and is axially slidably guided against the force of an elastic reset element (36) in the form of a helical spring. The end of the first push rod is constructed with a flat end face, through which the push rod (34) extends from the cylindrical opening (26) of the valve insert (22) with a working clearance A. The armature (38) of the solenoid valve (10) abuts against the end face of the push rod (34). The armature is axially slidably accommodated inside a hollow valve cover (40). The valve cover is domed and fixed to the outer periphery of the valve insert (22) with its open end. A circumferential welded connection is preferably used as the connection between the valve cover (40) and the valve insert (22).

[0021] The end of the push rod (34) facing the flat end is constructed as a pin-shaped, tapering closure (42), which is exemplarily constructed as a spherical section at its free end.

[0022] The transition portion from the closure (42) to the push rod (34) forms a radially surrounding support surface for the resilient reset element (36). The opposite end of the reset element (36) abuts against the valve body (44), which is press-fitted into the interior of the smaller diameter first sleeve section (24a) of the bearing sleeve (24) by a pressure medium.

[0023] The valve body (44) has a cap-like structure and is divided into a cylindrical stem (44a) and a bottom (44b), the bottom (44b) closing the stem (44a) at the end of the valve body facing the reset element (36). The bottom (44b) is formed into an inner cone-shaped valve seat (46) with a through hole leading to the base of the valve seat. The cross-section of the through hole constitutes the control cross-section (48) of the solenoid valve (10), which is controlled by the closure (42) of the push rod (34).

[0024] In the unenergized initial position shown in the figure of the solenoid valve (10), the closure (42) is lifted from the valve seat (46) by the mechanical force of the reset element (36), thereby opening the control cross section (48). When the solenoid coil (20) may be energized, the magnetic force of the magnetic circuit overcomes the mechanical force of the reset element (36), causing the closure (42) to close the control cross section (48), thereby cutting off the pressure medium connection between the first valve port (50) and the second valve port (52) of the solenoid valve (10).

[0025] The first valve port (50) is arranged on the outer periphery of the solenoid valve (10) in the transition area between the end of the valve insert (22) and the extended second sleeve section (24b) of the bearing sleeve (24).

[0026] The pressurized medium flowing into the solenoid valve (10) via the first valve port (50) is filtered for impurities by an installed filter. For this purpose, the filter comprises an annular filter (54) supported by a filter frame, with its pushrod-side end pressed against the filter seat (56) of the valve insert (22). The opposing end of the filter, away from the pushrod, forms a corresponding press-fit connection and a sealing connection with the outer periphery of the second sleeve section (24b) of the support sleeve (24) extending from the valve insert (22). The flowing pressurized medium reaches the mounting space of the reset element (36) or helical spring via a flow channel, and from there reaches the control cross section (48), which is internally constructed within the solenoid valve (10) between the inner periphery of the valve insert (22) and the outer periphery of the first pressed-in portion of the support sleeve (24). When the control cross section (48) is open, the pressure medium continues to flow into the valve body (44) and from there into the larger diameter second sleeve section (24b) of the bearing sleeve (24), and then to the second valve port (52).

[0027] The second valve interface is constructed at the connection point of the larger diameter second sleeve section (24b) of the bearing sleeve (24) to the hydraulic block (16), and includes a filter pressed into the bearing sleeve (24) from the circumferential side, the filter consisting of an annular filter housing and a flat filter (58) covering the annular opening, the flat filter being made of a fine filter screen.

[0028] Therefore, filters (54, 58) are provided at both valve ports (50, 52) because the solenoid valve (10) can be flowed through in two directions. The second flow direction is opposite to the flow direction mentioned above. The two filters (54, 58) at the two valve ports (50, 52) respectively keep the inside of the solenoid valve (10) free of impurities that may interfere with the sealing function of the closure (42) or the degree of freedom of movement of the movable valve components, or may cause wear of the movable components during the operation of the solenoid valve (10).

[0029] Of course, modifications can be made to the described embodiments of the solenoid valve without departing from the scope of protection defined by the claims.

Claims

1. A solenoid valve (10), specifically used for controlling the pressure medium connection between the master brake cylinder and the wheel brakes of an electronic anti-skid control vehicle braking system, the solenoid valve having: A valve housing in which a push rod (34) is accommodated, the push rod being able to slide against the force of an elastic reset element (36); The valve body (44) has a control cross section (48) surrounded by a valve seat (46), the control cross section being arranged between the first valve port (50) and the second valve port (52) of the solenoid valve (10). The closure (42), coupled to the push rod (34) to control the control cross section (48); and An armature (38) is displaceably arranged for manipulating the pushrod (34). Its features are, The valve housing is a multi-piece structure and includes a valve insert (22) that guides the push rod (34) and a support sleeve (24) that accommodates the valve body (44) and is inserted into the valve insert (22).

2. The solenoid valve according to claim 1, characterized in that, The bearing sleeve (24) can be manufactured by deep drawing process and has sleeve sections (24a; 24b) with different outer dimensions. The bearing sleeve (24) is pressed into the valve insert (22) with the first sleeve section (24a) having a smaller outer dimension than the second sleeve section (24b). The valve body (44) is housed in the first sleeve section (24a) in a pressure medium sealed manner. The second sleeve section (24b) extends from the valve insert (22) along the longitudinal axis L and forms one of the valve ports (52).

3. The solenoid valve according to claim 1 or 2, characterized in that, The second sleeve section (24b) is designed to be pressed into the corresponding orifice of the valve receiving part (14) of the hydraulic block (16) of the electronic anti-skid control vehicle braking system.

4. The solenoid valve according to claim 3, characterized in that, The valve insert (22) is manufactured by forming process, particularly by cold forming, and has a radially protruding flange (28). The solenoid valve (10) is fixed, particularly riveted, to the hydraulic block (16) of the hydraulic equipment of the electronic anti-slip control external force braking system by means of the flange.

5. The solenoid valve according to any one of claims 1 to 4, characterized in that, The valve ports (50, 52) are respectively equipped with filters (54; 58), wherein the first filter (54) is pressed against the outer periphery of the valve insert (22) with one end sealed and against the outer periphery of the second sleeve section (24b) with the other end sealed; and wherein the second filter (58) is pressed into the interior of the second sleeve section (24b) of the bearing sleeve (24) with its outer periphery pressed in.

6. The solenoid valve according to any one of claims 1 to 5, characterized in that, The first filter is a columnar annular filter (54), and the second filter is a flat filter (58).

7. The solenoid valve according to any one of claims 1 to 6, characterized in that, The transition portion of the bearing sleeve (24) from the first sleeve section (24a) to the second sleeve section (24b) forms a step (32), the step facing the annular surface at the end side of the valve insert (22).

8. The solenoid valve according to any one of claims 1 to 7, characterized in that, The valve body (44) is cup-shaped and has a hollow rod (44a) and a bottom (44b) at one end of the rod (44a), on which the valve seat (46) and the control cross section (48) are constructed.

9. The solenoid valve according to claim 8, characterized in that, The valve body (44) is pressed into the first sleeve section (24a) of the bearing element (24).

10. The solenoid valve according to any one of claims 1 to 9, characterized in that, A helical spring forms the reset element (36) for the push rod (34), the reset element being supported at one end on the bottom (44b) of the valve body (44).