Electrically controlled solenoid valve

Abstract

The invention relates to an electrically controllable solenoid valve, in particular for controlling and / or regulating a pressure medium connection in a hydraulic unit of an electronically slip-controlled vehicle braking system. Known solenoid valves 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 plunger (24). A closing element (24a) for controlling the control cross-section (22) is coupled to the plunger (24). To actuate the valve, a solenoid coil energizes a magnetic armature (34), which actuates the plunger (24) against the force of a return element (26). A lower part (14) with an end section (14a) is proposed, which is inserted into a lower part receptacle (16a) of the upper part (16). The end section (14a) has at least one recess (44) open towards the upper part (16), which penetrates a wall of the lower part (14) in a radial direction. The proposed lower part (14) reduces the height of a valve insert (12) within a housing block (40) without affecting the flow resistance, magnetic transition or stability of the valve insert (12) of a solenoid valve and also enables a cost-effective hydraulic power unit to be manufactured.

Description

Technical background:

[0001] The invention lies in the technical field of electronically slip-controlled vehicle braking 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 braking systems to release or block a pressure medium connection within a hydraulic unit.

[0002] A number of such solenoid valves are arranged together with an electrically controlled motor of a brake pressure generator on a housing block of this hydraulic unit and are supplied with electrical energy as required by an electronic control unit depending on detected sensor signals.

[0003] The solenoid valve according to the invention is preferably designed to control a hydraulic connection between a master brake cylinder and the wheel brakes of a brake circuit of the vehicle braking system. In normal operation, the solenoid valve interrupts this hydraulic connection, thereby disconnecting the driver from the wheel brakes. In fault mode, the solenoid valve releases this hydraulic connection, allowing the driver to build up brake pressure in the wheel brakes by muscle power and thus enabling the vehicle to be braked despite an electrical fault. State of the art

[0004] Electrically controlled solenoid valves according to the features of the preamble of claim 1 are well known from the prior art. 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 multiple parts for cost reasons and accordingly comprises an upper part and a lower part. Both housing parts are hollow cylindrical and overlap each other lengthwise in sections with projections facing each other. A first projection is formed on the upper part and engages in a receptacle on a second projection of the lower part. A plunger is slidably guided in the upper part, which carries a closing element 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.

[0005] To establish a pressure medium connection between a first pressure medium port located at the end face of a valve insert opposite the armature and a second pressure medium port located on the circumference of the valve insert, groove-shaped projections are provided on the upper part downstream of the control cross-section. These groove-shaped projections are divided into an axial groove section in the area of ​​axial overlap or an existing press fit between the upper and lower parts, and a radial groove section into which one end of the aforementioned axial groove section opens. 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 prevents a possible reduction in the axial overall length of this solenoid valve.

[0006] The reason for this is that a deeper insertion of the radial groove section 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 riveted to the housing block. This would result in radial riveting forces being absorbed less effectively or transferred less efficiently to the housing block.

[0007] Furthermore, the change in the cross-sectional area of ​​the valve insert caused by deeper radial groove sections would affect the magnetic transition between the upper and lower parts and could lead to a reduction in the magnetic force provided by the magnetic circuit.

[0008] Finally, deeper radial groove sections on the upper part would result in a strong flow deflection within a valve chamber, which increases the flow resistance of the solenoid valve.

[0009] The object of the present invention is therefore to provide a solenoid valve that avoids or improves upon these disadvantages described above. Advantages of the invention

[0010] 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 receptacle on the upper part. This end section has at least one recess open towards the upper part, which penetrates a wall of the lower part in a radial direction. The recess forms part of a pressure medium connection between the first and second pressure medium ports of the solenoid valve and offers the following advantages: • Due to the arrangement of the recess on the lower part, this recess is located on the same plane as the area of ​​the valve insert where the upper and lower parts are joined. This allows for a reduction in the axial length of the solenoid valve, particularly below a riveted flange. Furthermore, the first and second hydraulic fluid ports of the solenoid valve are positioned axially closer together, and the hydraulic fluid travels a shorter path when flowing through the valve chamber of the solenoid valve. Together with the resulting less pronounced deflection of the hydraulic fluid flow, this results in a lower flow resistance of a solenoid valve according to the invention. • The cross-section of the upper part in the area of ​​its riveting flange has no pressure-carrying channels and is therefore dimensionally stable. High riveting forces can be applied to anchor the solenoid valve to the housing block, or any riveting forces that occur can be more effectively transferred to the housing block via the valve insert. • 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.

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

[0012] An embodiment of the invention is shown in the drawing and is explained in detail in the following description.

[0013] The drawing includes two figures in which corresponding features are labelled with uniform reference numbers. • The Fig. Figure 1 shows a longitudinal section of a valve assembly of an electrically controlled solenoid valve designed according to the invention. This valve assembly is received in a valve receptacle of a housing block, from which the Fig. 1 shows the surrounding area of ​​this valve mount; • in the Fig. Figure 2 shows the lower part of a solenoid valve according to the invention as a single component in a perspective view and with a view towards the end face of this lower part facing the upper part. Drawing description

[0014] The Fig. The valve assembly (10) shown in Figure 1 is depicted without an attached solenoid coil for the sake of simplicity. It can be assumed that this valve assembly (10) can be fitted with an annular solenoid coil (not shown) that surrounds a so-called valve dome, which projects from the outer surface of a housing block (40). The valve assembly (10) and the solenoid coil together form the solenoid valve underlying the invention.

[0015] The valve assembly (10) shown comprises a valve housing or valve insert (12), which is formed in multiple 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) in order to create a force-fit / form-fit connection between the upper part (16) and the lower part (14). In the assembled state, 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 considerable distance and widens at the open end of the lower part (14), for example, in two right-angled steps.A cup-shaped valve body (20) is accommodated in the valve chamber (18). The base (20a) of the valve body is inserted into the open end of the lower part (14) and is firmly anchored in the smallest diameter region of this valve chamber (20), for example, by means of a press fit. A through-opening is formed in the center of the base of the valve body (20), which defines a control cross-section (22) of the solenoid valve. A pin-shaped closing element (24a) is provided for controlling the solenoid valve. This closing element is formed at one end of a plunger (24) facing the lower part (14). The plunger (24), in turn, is guided axially displaceably within the upper part (16) of the valve insert (12) by its circumferential wall.

[0016] A transition from the closing element (24a) to the plunger (24) forms a circumferential annular shoulder (24b), which serves as a support for one of the two ends of a return element (26) of the valve assembly (10) in the form of a coil spring. The coil spring rests with its opposite end against the base (20a) of the valve body (20). The return element (26), or coil spring, is centered on the closing element (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 element (24a) away 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 return element (26) is surrounded by the pressure medium.

[0017] The pressure medium enters the valve chamber (18) at a first pressure medium port (28) and exits this valve chamber (18) again via a second pressure medium port (30). In the invention, both pressure medium ports are arranged on the lower part (14) of the valve insert (12), with the first pressure medium port (28) being located at the open end of the lower part, while the second pressure medium port is located 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 associated with the pressure medium ports (28; 30).

[0018] To prevent impurities contained in the pressure medium from entering the valve chamber (18) or from being flushed from 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 end face of the valve insert (12). In contrast, the second filter element is sleeve-shaped and is pushed onto the lower part (14) of the valve insert (12) under radial preload.

[0019] A magnetic armature (34) is provided for actuating the plunger (24). This armature is positioned on the outer surface of the valve insert (12) facing the upper part (16) and rests with its armature end face on an end face of the plunger (24) facing away from the closing element. The magnetic armature (34) is axially movable inside a valve capsule (36) that is closed on one side in a dome shape. The open end of this valve capsule is attached to the outer circumference of the upper part (16) of the valve insert (12), in this exemplary embodiment by means of a circumferential weld.

[0020] The upper part (16) of the valve insert (12) has a multi-stepped outer contour and is divided into a cylindrical shaft (16b) to which the valve capsule (36) is attached, a transition section axially adjoining the shaft leading to larger outer dimensions of the valve insert (12), and a circumferential crimping flange (16c) at its end facing the lower part (14). This crimping flange (16c) is located at the same level 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).

[0021] Furthermore, the riveting flange (16c) extends radially outwards from the valve insert (12) to anchor the valve assembly (10) in an associated valve receptacle (38) on a housing block (40) of a hydraulic power unit. For this purpose, the valve assembly (10) is inserted into the valve receptacle (38) from the outside until the riveting flange (16c) rests against a shoulder (38a) formed by the valve receptacle (38) around its circumference. Subsequently, by a crimping or riveting process, material from the area surrounding the valve receptacle (38) of the housing block (40) is deformed into the interior of this valve receptacle (38) such that the deformed material covers at least segmental sections of the riveting flange (16c) of the valve body (20), thus securing the valve assembly to the housing block (40).By choosing the position of the shoulder (38a) within the valve receptacle (38), it is ensured that the pressure medium connections of the solenoid valve with associated pressure medium channels (42a; 42b) on the housing block (40) are contacted and hydraulically sealed against each other.

[0022] An electrically controlled magnetic coil (not shown) generates a magnetic field, causing a first magnetic pole to form on the end face of the magnetic armature (34) facing the plunger (24) and a second magnetic pole to form on the end face of the upper part (16) of the valve insert (12) facing the magnetic armature (34). The magnetic attraction between the magnetic poles causes the plunger (24) to actuate against the force of the return element (26). The magnetic armature (34) then approaches the valve insert (12) to within a small air gap between the facing end faces, and the closing element (24a) connected to the plunger (24) moves successively towards the control cross-section (22) until it finally rests on this control cross-section (22) and interrupts the connection between the pressure medium channels (42a: 42b).

[0023] Fig.Figure 2 shows the lower part (14) of the valve insert (12) as a separate component in a perspective view. This lower part (14) is recognizable 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). 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 essential for the invention and can be freely selected depending on the application.

[0024] These recesses (44) have an open end facing the upper part (16) and penetrate the wall of the lower part (14) in a radial direction. At the outer circumference of the lower part (14), the recesses (44) each transition into a longitudinal groove (45) which runs in the direction of the longitudinal axis L and terminates approximately in the middle of the lower part (14) at a conically circumferential transition section. At the transition section, the dimensions of the lower part increase to an outer diameter that is slightly larger than the outer diameter of the lower part (14) in the area of ​​the recesses (44) or longitudinal grooves (45). A cylindrical section adjoins the transition section and extends to the end face of the lower part (14).

[0025] The upwardly open recesses (44), together with the outwardly open longitudinal grooves (45) on the circumference of the lower part (14), form pressure-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 formed on the sleeve-shaped lower part (14) by forming techniques, for example by cold forging.

[0026] According to the invention, in the assembled solenoid valve, the crimping flange (16c) and the end region (14a), where the lower part (14) and the upper part (16) of the valve insert (12) are joined, are located on at least approximately the same plane. This results, on the one hand, in a reliable fastening of the individual parts of the valve insert (12) to one another and, on the other hand, in a rigid fastening of the valve assembly (10) to the housing block (40) of a hydraulic power unit. In addition, the recesses (44) and longitudinal grooves (45), i.e., the pressure medium channels, are formed only on the lower part (14), which allows for a valve assembly (10) with a particularly short axial length. The pressure medium connections (28; 30) of the solenoid valve according to the invention are positioned axially close to each other, resulting in a short flow path along which the pressure medium flows through the solenoid valve or the valve assembly (10).This flow path is also free of significant flow deflections, so that the solenoid valve or the valve assembly (10) of the solenoid valve exhibits low flow resistance. The individual parts of the valve insert (12) can be manufactured using forming techniques and are therefore cost-effective. The upper part (16) of the valve assembly (10) does not require any pressure-carrying channels and can therefore, due to its stability, effectively transfer any radial clamping forces that occur to the housing block (40).

[0027] Of course, modifications or advantageous further developments compared to the described embodiment are conceivable, which do not deviate from the scope of protection specified by the claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 219 955 A1

[0004]

Claims

[1] Electrically controlled 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) comprising 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 plunger (24) for controlling the control cross-section (22) and an actuatable magnetic armature (34) which acts on the plunger (24) against the force of a return element (26), characterized by , 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 portion (14a) has at least one recess (44) open towards the upper part (16) and penetrating a wall of the lower part (14) in the radial direction. [2] Solenoid valve according to claim 1, characterized by 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 by 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 by that the lower part (14) and the upper part (16) can be produced by forming, in particular by cold forming. [5] Solenoid valve according to one of claims 1 to 4, characterized bythat 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 by , that a valve body (20) is inserted into the lower part (14), on which 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 by that the plunger (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 by 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 by 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 axially fixed in a diameter step. [10] Solenoid valve according to claim 9, characterized by 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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