Electrically drivable solenoid valve

Abstract

The invention relates to an electrically drivable solenoid valve, in particular for open- and / or closed-loop control of a pressure medium connection in a hydraulic unit of an electronically slip-controllable vehicle braking system. Solenoid valves known for this purpose have a valve insert (12) consisting of a lower part (14) with a control cross-section (22) and an upper part (16) for guiding a tappet (24). A closing element (24a) for controlling the control cross-section (22) is coupled to the tappet (24). To actuate the valve, a magnetic coil acts on a magnetic armature (34), which actuates the tappet (24) against the force of a return element (26). The invention proposes a lower part (14) with an end portion (14a) which is inserted into a lower part receptacle (16a) in the upper part (16). The end portion (14a) has at least one recess (44) which is open towards the upper part (16) and penetrates a wall of the lower part (14) in the radial direction. The proposed lower part (14) reduces the height of a valve insert (12) within a housing block (40) without impairing the flow resistance, magnetic transition or stability of the valve insert (12) of a solenoid valve and in addition enables a hydraulic unit to be manufactured cost-effectively.

Description

[0001] Disclosure of the invention

[0002] Title:

[0003] Electrically controlled solenoid valve

[0004] Technical background:

[0005] The invention lies in the technical field of electronically controlled slip-controllable vehicle brake systems and relates to an electrically controllable solenoid valve according to the features of the preamble of claim 1, which is used in such vehicle brake systems to release or block a pressure medium connection within a hydraulic unit.

[0006] For this purpose, a plurality of such solenoid valves are arranged on a housing block of this hydraulic unit together with a motor of a brake pressure generator, which can also be controlled electrically, and are supplied with electrical energy as required by an electronic control unit depending on the sensor signals detected.

[0007] The solenoid valve according to the invention is preferably provided for controlling a pressure medium connection between a master brake cylinder and the wheel brakes of a brake circuit of the vehicle's braking system. During normal operation, the solenoid valve interrupts this pressure medium connection, thus disconnecting the driver from the wheel brakes. During fault operation, the solenoid valve releases this pressure medium connection, allowing the driver to build up braking pressure in the wheel brakes using muscle power, and thus braking the vehicle despite the presence of an electrical fault.

[0008] State of the art

[0009] Electrically controllable solenoid valves according to the features of the preamble of claim 1 are well known from the prior art.

[0010] By way of example, reference is made in this context to the disclosure in DE 10 2018 219 955 A1. In the solenoid valve disclosed here, the valve housing or valve insert is designed in several parts for cost reasons and accordingly comprises an upper part and a lower part. Both housing parts are hollow cylindrical and overlap lengthwise in sections with extensions that face each other. A first extension is formed on the upper part and engages in a receptacle on a second extension of the lower part. A plunger is slidably guided in the upper part and carries a closing body of the solenoid valve at its end. A control cross-section of the solenoid valve, controlled by this closing element, is arranged on the lower part.

[0011] To create a pressure medium connection between a first pressure medium connection located on the end face of a valve insert facing away from the armature and a second pressure medium connection located on the circumference of the valve insert, groove-shaped formations are provided on the upper part downstream of the control cross-section. These groove-shaped formations are divided into an axial groove section in the area of ​​axial overlap or an existing press connection between the upper part and the lower part, and a radial groove section into which the aforementioned axial groove section opens with one of its ends. Viewed in the longitudinal direction of the solenoid valve, the radial groove section is located above the area where the upper and lower parts overlap and therefore precludes a possible reduction in the axial length of this solenoid valve.

[0012] The reason for this is that inserting the radial groove section deeper into the upper part would weaken the cross-section of the valve insert in an area where a valve flange of the solenoid valve is formed and where the solenoid valve is caulked to the housing block. This would make it more difficult to absorb any radial caulking forces or to transfer them to the housing block.

[0013] The cross-sectional change of the valve insert caused by deeper radial groove sections would also influence the magnetic transition between the upper and lower sections and could lead to a reduction in the magnetic force provided by the magnetic circuit. Finally, deeper radial groove sections on the upper section would result in a strong flow deflection within a valve chamber, which would increase the flow resistance of the solenoid valve.

[0014] The object of the present invention is therefore to provide a solenoid valve which avoids or improves these disadvantages.

[0015] Advantages of the invention

[0016] In a solenoid valve according to the invention, the lower part is connected to the upper part by an end section that can be inserted into an associated lower part receptacle on the upper part. This end section has at least one recess open toward the upper part, which penetrates a wall of the lower part in a radial direction. The recess is part of a pressure medium connection between the first and second pressure medium connections of the solenoid valve and offers the following advantages:

[0017] • Due to the arrangement of the recess on the lower part, this recess is located on the same level as the area of ​​the valve insert where the upper and lower parts are joined. This allows for a shortening of the axial length of the solenoid valve, particularly below a caulking flange. Furthermore, the first and second pressure medium connections of the solenoid valve are axially closer together, and the pressure medium travels a shorter distance when flowing through the valve chamber of the solenoid valve. Together with the resulting less severe deflection of the pressure medium flow, this results in a lower flow resistance of a solenoid valve according to the invention.

[0018] • The cross-section of the upper part in the area of ​​its caulking flange does not require any pressure-medium-carrying channels and is therefore dimensionally stable. High caulking forces can be applied to anchor the solenoid valve to the housing block, or any caulking forces that occur can be better dissipated to the housing block via the valve insert.

[0019] • The influence of the pressure-medium-carrying channels on the magnetic circuit is reduced because the upper and lower parts have a larger common contact area. Further advantages or advantageous developments of the invention will become apparent from the dependent claims or the following description.

[0020] drawing

[0021] An embodiment of the invention is illustrated in the drawing and is explained in detail in the following description.

[0022] The drawing comprises two figures in which corresponding features are provided with identical reference numbers.

[0023] • Figure 1 shows a longitudinal section of a valve assembly of an electrically controllable solenoid valve designed according to the invention. This valve assembly is accommodated in a valve receptacle of a housing block, of which Figure 1 shows the surrounding area of ​​this valve receptacle.

[0024] • in Figure 2, the lower part of a solenoid valve according to the invention is shown as an individual part in a perspective view and with a view towards the end face of this lower part facing the upper part.

[0025] Drawing description

[0026] The valve assembly (10) shown in Figure 1 is depicted without a mounted solenoid coil for the sake of simplicity. It is assumed that this valve assembly (10) can be equipped with a ring-shaped solenoid coil (not shown) that encloses a so-called valve dome, which protrudes beyond the outer side of a housing block (40). The valve assembly (10) and solenoid coil together form the solenoid valve underlying the invention.

[0027] The valve assembly (10) shown comprises a valve housing or a valve insert (12), which is constructed in several parts and consists of a lower part (14) and an upper part (16). The upper and lower parts are each hollow-cylindrical or sleeve-shaped and are coaxially inserted into one another. According to the invention, the lower part (14) has an end section (14a) with which it is pressed into a lower part receptacle (16a) formed on the upper part (16), thus creating a force-fitting / positive connection between the upper part (16) and the lower part (14).When joined, the upper part (16) and the lower part (14) enclose a continuous cylindrical valve chamber (18) with an inner diameter that remains constant axially over a long distance and widens at the front, open end of the lower part (14), for example in two right-angled steps. The valve chamber (18) accommodates a cup-shaped valve body (20) which is inserted with its base (20a) first into the open end of the lower part (14) and is firmly anchored in the region of this valve chamber (20) with the smallest diameter, for example by means of a press connection. In the center of the base of the valve body (20) there is a through-opening which defines a control cross-section (22) of the solenoid valve. For controlling the valve, a pin-shaped closing element (24a) is provided which is formed on one end of a tappet (24) facing the lower part (14).The tappet (24) in turn is guided with its peripheral wall axially displaceably in the upper part (16) of the valve insert (12).

[0028] A transition from the closing member (24a) to the tappet (24) forms a circumferential annular shoulder (24b), which serves as a support for a first of the two ends of a return element (26) of the valve assembly (10) in the form of a spiral spring. With its opposite second end, the spiral spring rests on the bottom (20a) of the valve body (20). The return element (26) or spiral spring is centered on the closing member (24a) and surrounds the control cross-section (22) of the valve assembly (10) formed on the valve body (20). The effect of the return element (26) is to lift the closing member (24a) from the control cross-section (22) when the solenoid valve is not electrically actuated, thereby opening this control cross-section (22) and allowing a pressure medium to flow through the valve chamber (18) or the control cross-section (22). In this case, the pressure medium flows around the return element (26).

[0029] The pressure medium enters the valve chamber (18) at a first pressure medium connection (28) and exits this valve chamber (18) again via a second pressure medium connection (30). In the invention, both pressure medium connections are arranged on the lower part (14) of the valve insert (12), with the first pressure medium connection (28) being located at the frontal, open end of the lower part, while the second pressure medium connection is arranged on the circumference of the end of the lower part (14) closest to the upper part (16). Pressure medium channels (42a; 42b) of the housing block (40) are assigned to the pressure medium connections (28; 30).

[0030] To prevent impurities contained in the pressure medium from penetrating the valve chamber (18) or being flushed out of the valve chamber (18) into the downstream pressure medium circuit, filter elements (32a, b) are assigned to the pressure medium connections (28; 30). A first filter element (32a) is designed as a flat filter, the filter body of which is pressed into one of the diameter steps at the front end of the valve insert (12). The second filter element, in contrast, is sleeve-shaped and is pushed onto the outside of the lower part (14) of the valve insert (12) under radial preload.

[0031] To actuate the tappet (24), a magnetic armature (34) is provided, which is placed on the outer side of the valve insert (12) facing the upper part (16), where its armature face rests on a face of the tappet (24) facing away from the closing member. The magnetic armature (34) is arranged in an axially movable manner inside a valve capsule (36) that is closed on one side in a dome-shaped manner and is fastened by its open end to the outer circumference of the upper part (16) of the valve insert (12), in the exemplary embodiment by means of a circumferential welded joint.

[0032] The upper part (16) of the valve insert (12) has a multiply stepped outer contour and is divided into a cylindrical shaft (16b) to which the valve capsule (36) is attached, an axially adjoining transition section towards the larger outer dimensions of the valve insert (12), and a circumferential caulking flange (16c) at its end facing the lower part (14). This caulking flange (16c) is located at the same height as the lower part receptacle (16a) formed on the upper part (16), thereby achieving a largely constant wall cross-section of the upper part (16).

[0033] Furthermore, the caulking flange (16c) protrudes radially outward from the valve insert (12) in order to anchor the valve assembly (10) in an associated valve receptacle (38) on a housing block (40) of a hydraulic unit. For this purpose, the valve assembly (10) is inserted from the outside into the valve receptacle (38) until the caulking flange (16c) rests circumferentially against a shoulder (38a) formed by the valve receptacle (38). Subsequently, the valve assembly (10) is secured by a stamping orDuring the caulking process, material from the area surrounding the valve receptacle (38) of the housing block (40) is deformed into the interior of the valve receptacle (38) in such a way that the deformed material covers the caulking flange (16c) of the valve body (20) at least in segmental sections and thus fixes the valve assembly to the housing block (40). The selection of the position of the shoulder (38a) within the valve receptacle (38) ensures that the pressure medium connections of the solenoid valve are in contact with the associated pressure medium channels (42a; 42b) on the housing block (40) and are hydraulically sealed off from one another.

[0034] Electrical control of the magnetic coil (not shown) generates a magnetic field, resulting in the formation of a first magnetic pole on the end face of the magnet armature (34) facing the tappet (24) and a second magnetic pole on the end face of the upper part (16) of the valve insert (12) facing the magnet armature (34). The magnetic attraction force acting between the magnetic poles causes the tappet (24) to be actuated counter to the force of the return element (26). The magnet armature (34) thereby approaches the valve insert (12) to within a small air gap between the facing end faces, and the closing element (24a) connected to the tappet (24) moves successively toward the control cross-section (22) until it ultimately rests on this control cross-section (22) and interrupts the connection between the pressure medium channels (42a: 42b).

[0035] Figure 2 shows the lower part (14) of the valve insert (12) as a single part in perspective. This lower part (14) is clearly designed as a sleeve-shaped formed part, in particular as a cold-forged part, which has recesses (44) at its end section (14a) pressed into the upper part (16). By way of example, in the illustrated embodiment, three such recesses (44) are arranged at equal angular intervals across the end face, whereby the number, arrangement, or dimensions of the recesses (44) are not critical to the invention and can be freely selected depending on the specific application.

[0036] These recesses (44) have an open end facing the upper part (16) and penetrate the wall of the lower part (14) in the radial direction. On the outer circumference of the lower part (14), the recesses (44) each merge into a longitudinal groove (45) which runs in the direction of the longitudinal axis L and ends approximately in the middle of the lower part (14) at a conical transition section. At the transition section, the dimensions of the lower part increase to an outer diameter which is slightly larger than the outer diameter of the lower part (14) in the area of ​​the recesses (44) or longitudinal grooves (45). Adjoining the transition section is a cylindrical section which extends to the front end of the lower part (14).

[0037] The upwardly open recesses (44), together with the outwardly open longitudinal grooves (45) on the circumference of the lower part (14), form pressure-medium-carrying channels through which the pressure medium flows out of the valve chamber (18). Since these channels are open to the outside, they can be produced by forming, for example, by cold-forming, on the sleeve-shaped lower part (14).

[0038] According to the invention, in the assembled solenoid valve, the caulking flange (16c) and the end region (14a) at which the lower part (14) and the upper part (16) of the valve insert (12) are joined together are located on at least approximately the same plane. This results, on the one hand, in reliable fastening of the individual parts of the valve insert (12) to one another and, on the other hand, in rigid fastening of the valve assembly (10) to the housing block (40) of a hydraulic unit. In addition, the recesses (44) and longitudinal grooves (45), i.e. the pressure medium-carrying channels, are formed only on the lower part (14), which allows a valve assembly (10) with a particularly short axial length. The pressure medium connections (28; 30) in the solenoid valve according to the invention are positioned axially close to one another, resulting in a short flow path along which the pressure medium flows through the solenoid valve or the valve assembly (10).This flow path also avoids significant flow deflections, so that the solenoid valve or the valve assembly (10) of the solenoid valve exhibits low flow resistance. The individual components of the valve insert (12) are formed and thus cost-effective to manufacture. The upper part (16) of the valve assembly (10) does not require any pressure-medium-carrying channels and, due to its stability, can therefore effectively dissipate any radial caulking forces to the housing block (40).

[0039] Of course, changes or advantageous developments compared to the exemplary embodiment explained are conceivable, which do not depart from the scope of protection specified by the claims.

Claims

Claims 1 . Electrically controllable solenoid valve, in particular for controlling and / or regulating a pressure medium connection in a hydraulic unit of an electronically controlled slip-controllable vehicle brake system, with a valve insert (12) which has a lower part (14) with a control cross-section (22) and an upper part (16) connected to the lower part (14) for guiding a tappet (24), a closing member (24a) coupled to the tappet (24) for controlling the control cross-section (22) and an actuatable magnetic armature (34) which acts on the tappet (24) counter to the force of a return element (26), characterized in that the lower part (14) can be inserted with an end section (14a) into an associated lower part receptacle (16a) of the upper part (16), wherein the end section (14a) has at least one recess (44) open towards the upper part (16) and penetrates a wall of the lower part (14) in the radial direction.

2. Solenoid valve according to claim 1, characterized in that the recess (44) opens into a longitudinal channel (45) formed on the outer circumference of the lower part (14).

3. Solenoid valve according to claim 1 or 2, characterized in that the lower part receptacle (16a) of the upper part (16), viewed in the direction of a longitudinal axis L of the valve insert (12), is arranged at a level with a caulking flange (16c).

4. Solenoid valve according to one of claims 1 to 3, characterized in that the lower part (14) and the upper part (16) can be produced by forming technology, in particular by cold forming technology.

5. Solenoid valve according to one of claims 1 to 4, characterized in that the lower part (14) and the upper part (16) are connected to one another in a form-fitting and / or force-fitting manner, preferably by mutual pressing.

6. Solenoid valve according to one of claims 1 to 5, characterized in that a valve body (20) is inserted into the lower part (14), on which valve body the control cross section (22) of the solenoid valve is formed and on which the return element (26) is axially supported with a first of its ends.

7. Solenoid valve according to one of claims 1 to 6, characterized in that the tappet (24) has an annular shoulder (24b) on which the return element (26) is supported with a second of its ends.

8. Solenoid valve according to one of claims 1 to 7, characterized in that the return element (26) is arranged between the tappet (24) and the valve body (20) in a section of a valve chamber (18) through which the pressure medium flows.

9. Solenoid valve according to one of claims 6 to 8, characterized in that the lower part (14) has, at its end facing away from the upper part (16), an inner diameter which decreases in a step-like manner from the outside to the inside, wherein a filter element (32a) is arranged in an axially fixed manner in a diameter step.

10. Solenoid valve according to claim 9, characterized in that the valve body (20) and the filter element (32a) are each fastened in a force-fitting and / or form-fitting manner inside the lower part (14).

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