Screen for a hydraulic control

Abstract

A strainer (1) for a hydraulic control system, comprising a valve housing, a channel housing, and an intermediate plate (7) defining an oil-carrying channel (9) in the valve or channel housing. The strainer (1) comprises a frame (2) injection-molded from plastic and a filter mesh (3) received in the frame (2). It is characterized in that the frame (2) has means (5) on the lateral surfaces (4) facing the valve or channel housing in the assembled state for preventing the frame (2) from falling out during assembly. At least one elastic element (6) is provided on the lower side of the frame (2), which elastic element (6) serves to press the strainer (1) against the intermediate plate (7) in the assembled state. The elastic element (6) is designed such that the strainer (1) projects beyond the valve or channel housing of the hydraulic control system during assembly when the intermediate plate (7) has not yet been assembled.

Description

[0001] The present invention relates to a strainer for a hydraulic control system, as well as a hydraulic control system incorporating such a strainer. Hydraulic control systems are known from the prior art and are used, for example, in industrial hydraulics, brake hydraulics, aircraft hydraulics, and transmission technology. In these systems, electrical signals are converted into hydraulic signals by means of a hydraulic control system.

[0002] Automatic transmissions in motor vehicles feature a hydraulic transmission control unit, which converts the electrical signals from an electronic transmission control unit into hydraulic signals. These signals actuate the transmission's shift elements and supply the starting element, such as a hydrodynamic torque converter, with the necessary lubrication and cooling oil. The hydraulic transmission control unit also provides purely hydraulic functions for controlling the transmission, such as forward and reverse driving, oil pressure for hydraulic valves, lubrication oil quantity control, and emergency driving functions.

[0003] A hydraulic control system, for example a hydraulic transmission control system, therefore has at least two housing parts made of die-cast parts, namely a channel housing and a valve housing, which are separated by an intermediate plate, wherein openings are provided in the intermediate plate that allow oil to flow between the two housing parts and serve to implement hydraulic functions, such as a throttling function, an orifice function or the function of a check valve.

[0004] According to current technology, filters are installed in hydraulic control systems to protect components such as baffles from contamination. In hydraulic control systems, these filters are typically installed in the channel housing, usually in the supply and return lines to and from the gearbox's switching elements. Furthermore, all supply and return lines to the gearbox should be equipped with filters, for example, all hydraulic interfaces between the intermediate plate and the channel housing.

[0005] From DE 10 2008 035 874 A1, an arrangement is known comprising a filter housing and a filter element which is positioned in an opening of the filter housing, wherein the filter element has a bellows made of a filter medium which is connected to a cover for closing the opening of the filter housing, and wherein the cover is sealed against a wall of the filter housing by means of spring connecting elements.

[0006] A sieve is known from US patent 2006 / 226066 A1 which can be fastened by means of at least one snap fastener.

[0007] The present invention is based on the objective of providing a sieve for a hydraulic control system.

[0008] This problem is solved by the features of claim 1. Further embodiments and advantages of the invention are set out in the dependent claims.

[0009] Accordingly, a strainer for a hydraulic control system is proposed, comprising a valve housing, a channel housing, and an intermediate plate as a boundary for an oil-carrying channel in the valve or channel housing. The strainer has a frame injection-molded from plastic and a filter mesh held within the frame, for example, made of an embedded wire mesh or injection-molded plastic mesh. The strainer according to the invention can be installed directly in front of a channel end or at any point in the oil-carrying channel.

[0010] The frame has means on its lateral surfaces facing the valve or duct housing when assembled, which prevent the frame from falling out during assembly, particularly during assembly within the valve housing. These means for preventing the frame from falling out during assembly can be means for creating a friction-fit connection between the frame and the corresponding duct surfaces; for example, the means can be designed as elastic thickenings.

[0011] According to an advantageous embodiment, the frame can have lips on the lateral surfaces facing the valve or duct housing in the assembled state as a means of preventing the frame from falling out during assembly, which act as barbs to prevent it from falling out during assembly.

[0012] According to a further advantageous embodiment, the lips can be replaced by elastic arches, which, due to their elasticity, prevent the frame from falling out. In contrast to a design with lips, this facilitates handling the sieve in larger quantities, for example, as bulk material, by preventing the lips of several sieves from becoming entangled. It is also conceivable to use both lips and arches.

[0013] According to the invention, at least one elastic element, for example a lip, is provided on the lower side of the frame. In the assembled state, this element serves to press the screen against the intermediate plate to create a seal. The elastic element is designed such that, during assembly (before the intermediate plate is installed), the screen projects beyond the valve or duct housing, preferably beyond all tolerances. When the intermediate plate is installed, the screen is pressed down.

[0014] According to one embodiment of the invention, the frame has a circumferential partial thickening at the point where the filter mesh is connected to the frame, which serves to stabilize the sieve, for example when the filter mesh is injected as a metal mesh, and advantageously results in a reduction of the thickness of the frame.

[0015] At the point in an oil-carrying channel where the strainer according to the invention is inserted, the channel is raised on both sides and widened by a chamfer so that the overall oil cross-section is not impaired. Raising the channel on both sides creates a recess for the strainer. This advantageously means that the strainer is not inserted as deeply into the channel or valve housing, thus minimizing the thickening of the channel or valve housing on its rear side.

[0016] Since the sieve sits deeper than the oil-carrying channel when installed, it is pressed axially against the corresponding inner side of the recess formed by the channel's elevations by the oil flow in the channel, thus achieving a further seal.

[0017] The sieve and filter mesh are preferably trapezoidal in shape, with the oil-carrying channel having corresponding draft angles to the casting demolding. The trapezoidal shape facilitates bidirectional flow and a constant mesh size.

[0018] In the event that the sieve is used in the middle of an oil-carrying channel, the channel inlet and outlet are preferably designed identically.

[0019] The intermediate plate of the hydraulic control unit can be designed with at least one orifice plate, in which case the strainer is preferably installed directly in front of the orifice plate. According to a further embodiment, the frame of the strainer according to the invention has recesses on its upper side; this offers the advantage that, if the orifice plate is provided at a channel outlet, the orifice plate can be made as large as possible, since the recesses allow more clearance for the orifice plate.

[0020] No additional machining of the duct or valve housing is required for the installation of the strainer. Furthermore, the trapezoidal design of the strainer and the corresponding draft angles of the duct or valve housing prevent incorrect installation.

[0021] The invention is explained in more detail below with reference to the accompanying figures. Identical reference numerals in the figures denote identical components. They show: Fig. 1a: A schematic perspective view of an embodiment of a sieve constructed according to the invention; Fig. 1b: A schematic front view of the design according to Fig. 1a; Fig. 1c: A detailed view of the in Fig. 1a and Fig. 1 b shown sieve to illustrate the design of the point where the filter mesh is connected to the frame; Fig. 2: A schematic sectional view showing part of an oil-carrying channel; Fig. 3a: A schematic sectional view along the in Fig. 2 shown line AA; Fig. 3b: A schematic sectional view along the in Fig. 3a shown line BB Fig. 4: A schematic sectional view along the in Fig. 3a shown line BB before the intermediate plate is fitted; Fig. 5: A schematic sectional view along the in Fig. 3a line BB shown after the intermediate plate has been fitted; and Fig. 6: A schematic sectional view along the in Fig. Line AA shown in 2 after the intermediate plate has been fitted, with the sieve being inserted directly in front of a baffle provided at a channel outlet. Fig. 7: A schematic front view of an alternative embodiment of a sieve designed according to the invention; Fig. 8: A schematic front view of a further alternative embodiment of a sieve designed according to the invention;

[0022] According to the invention and with reference to Fig. 1a and Fig. 1b comprises a sieve 1 designed according to the invention for a hydraulic control for insertion into an oil-carrying channel in the valve or channel housing, a frame 2 made of injection-molded plastic and a filter mesh 3 made of an embedded wire mesh or injection-molded plastic mesh received in the frame 2.

[0023] According to the invention, the frame 2 has means 5 on its lateral surfaces 4 facing the valve or duct housing in the assembled state, which prevent the frame from falling out during assembly, particularly during assembly in the valve housing. In the example shown, the frame 2 has lips on its lateral surfaces 4 facing the valve or duct housing in the assembled state as means 5 for preventing the frame 2 from falling out during assembly. These lips act as barbs to prevent the frame 2 from falling out. Alternatively or additionally to the lips, elastic arcs can be provided.

[0024] Furthermore, at least one elastic element 6 is provided on the lower side of the frame 2, which in the example shown is designed as a pair of lips. In the assembled state, the elastic element 6 serves to press the sieve 1 against the intermediate plate 7 in order to create a seal. This situation is illustrated by Fig. Figure 5 illustrates this. The elastic element 6 can, for example, also be designed as a spring element.

[0025] The elastic element 6 is designed such that, during assembly, when the intermediate plate 7 has not yet been installed, the sieve 1 projects beyond all tolerances of the valve or channel housing of the hydraulic control, as shown by the Fig. Figure 4 illustrates how the sieve 1 is pressed down during the assembly of the intermediate plate 7.

[0026] Referring to Fig. 1c the frame 2 of the sieve 1 has a circumferential partial thickening 8 at the point where the filter mesh 3 is connected to the frame 2, which increases the stability of the sieve 1 and results in a reduction of the thickness of the frame 2.

[0027] According to the invention and with reference to Fig. 2, Fig. 3a and Fig. 3b The sieve 1 according to the invention can be inserted into a receptacle 10 formed by raising the oil-carrying channel 9 on both sides at the point where the sieve is to be inserted, wherein the channel is widened at this point by means of a chamfer 11 so that the overall oil cross-section is not impaired. Fig. 2 the channel inlet is designated with reference numeral 13, and the channel outlet is designated with reference numeral 14.

[0028] Because the recess for the sieve 1 is created by raising the channel 9, the sieve 1 is advantageously not inserted so deeply into the channel or valve housing, which reduces the required thickening 15 of the channel or valve housing at the rear of the channel or valve housing to a minimum.

[0029] In the examples shown, the sieve 1 and the filter mesh 3 are trapezoidal in shape, with the oil-carrying channel 9 having corresponding draft angles 12.

[0030] At the in Fig. In the example shown in Figure 6, the intermediate plate 7 of the hydraulic control has an orifice 16, with the sieve 1 being inserted directly in front of the orifice 16 in the direction of flow.

[0031] As from Fig. 1a, Fig. 1b, Fig. 4 and Fig. As can be seen in Figure 5, the frame 2 of the sieve 1 can have recesses 17 on the upper side, which means that if the aperture 16 is provided at a channel outlet, it can be made as large as possible, since the recesses 17 allow more clearance for the aperture.

[0032] Fig. Figure 7 shows a schematic front view of an alternative embodiment of a sieve 1 designed according to the invention. The means 5 for preventing the frame 2 from falling out during assembly are now designed as elastic arcs instead of lips. The elastic element 6 is still designed as a pair of lips.

[0033] Fig. Figure 8 shows a schematic front view of a further alternative embodiment of a sieve 1 carried out according to the invention, which is essentially the embodiment according to Fig. 7 corresponds. Now the elastic element 6 is also designed as an elastic arc. Reference sign 1 sieve 2 frames 3 filter mesh 4 side surfaces 5 ways to prevent the frame from falling out 6 elastic elements 7 Intermediate plate 8 partial thickening 9 oil-carrying channel 10 recording 11th phase 12 Draft angle 13 Channel Inlet 14 Channel outlet 15 Thickening 16 aperture 17 recess

Claims

[1] A screen (1) for a hydraulic control system comprising a valve housing, a channel housing and an intermediate plate (7) as a boundary of an oil-carrying channel (9) in the valve or channel housing, the screen (1) comprising a plastic injection-molded frame (2) and a filter mesh (3) received in the frame (2), characterized by , that the frame (2) has means (5) on the lateral surfaces (4) facing the valve or channel housing in the assembled state to prevent the frame (2) from falling out during assembly, wherein at least one elastic element (6) is provided on the lower side of the frame (2) which, in the assembled state, serves to press the screen (1) against the intermediate plate (7), wherein the elastic element (6) is designed such that, during assembly, when the intermediate plate (7) has not yet been installed, the screen (1) projects beyond the valve or channel housing of the hydraulic control. [2] Sieve (1) for a hydraulic control system according to claim 1, characterized by , that at least part of the means (5) for preventing the frame (2) from falling out during assembly are designed as lips which act as barbs to prevent the frame (2) from falling out. [3] Sieve (1) for a hydraulic control system according to claim 1 or claim 2, characterized by , that at least part of the means (5) for preventing the frame (2) from falling out during assembly are designed as elastic arches which, due to their elasticity, prevent the frame (2) from falling out. [4] Sieve (1) for a hydraulic control system according to claim 1, characterized by , that the means (5) for preventing the frame (2) from falling out during assembly are designed as means for creating a friction-fit connection between the frame (2) and the corresponding channel surfaces. [5] Sieve (1) for a hydraulic control according to claim 1, 2, 3 or 4, characterized by , that the elastic element (6) is designed as a pair of lips or as an elastic arc. [6] Sieve (1) for a hydraulic control according to claim 1, 2, 3, 4 or 5, characterized by , that the frame (2) of the sieve (1) has a circumferential partial thickening (8) at the point where the filter mesh (3) is connected to the frame (2), which increases the stability of the sieve (1) and results in a reduction of the thickness of the frame (2). [7] Sieve (1) for a hydraulic control system according to one of the preceding claims, characterized by , that the frame (2) of the sieve (1) has recesses (17) on the upper side which result in the aperture (16) being made as large as possible when the sieve (1) is inserted directly in front of an aperture (16) formed in the intermediate plate (7) and provided at a channel outlet. [8] Sieve (1) for a hydraulic control system according to one of the preceding claims, characterized by , that it can be inserted into a receptacle (10) created by raising the oil-carrying channel (9) on both sides at the point where the sieve (1) is to be inserted, wherein the channel (9) is made wider at this point by means of a chamfer (11) so that the overall oil cross-section is not affected. [9] Sieve (1) for a hydraulic control system according to one of the preceding claims, characterized by , that the sieve (1) and the filter mesh (3) are trapezoidal in shape, with the oil-carrying channel (9) having corresponding draft angles (12). [10] Hydraulic control with a sieve (1) according to any one of claims 1 to 9.

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