Slide valve, especially for controlling a motor vehicle automatic transmission

Abstract

Slide valve (10), in particular for controlling a motor vehicle automatic transmission, with a housing (12) which has an axial end section (14), wherein a connecting sleeve (34) is arranged on the axial end section (14) of the housing (12), which has a first diameter (38) in a first axial region (36) adjacent to the housing (12) and a second diameter (42) in a second axial region (40) remote from the housing (12), wherein the first diameter (38) is larger than the second diameter (42) and wherein a filter device (58) is arranged in the first axial region (36) and the second axial region (40) comprises a hydraulic connection (44), characterized in that the filter device (58) has a radially outer annular filter section (62) and a radially inner, substantially hat-shaped support section (84),on which a valve spring (86) of the slide valve (10) is supported.

Description

State of the art

[0001] The invention relates to a slide valve according to the preamble of claim 1.

[0002] Automatic transmissions for motor vehicles, which use hydraulically actuated clutches to change gears, are well-known in the market. For shifting to be smooth and imperceptible to the driver, the hydraulic components require a comparatively high degree of precision. For example, electromagnetically actuated pressure control valves are used for this purpose. Such pressure control valves can be affected during operation by dirt particles in the fluid being controlled. Therefore, filters are often incorporated to remove these particles from the fluid. Patent publications in this field include, for example, DE 198 47 304 C2, DE 10 2005 059 433 A1, DE 197 33 660 A1, and DE 10 2010 039 918 A1.

[0003] From DE 198 36 494 A1, an electromagnetic valve with a housing and a connecting sleeve is known, wherein the connecting sleeve has a first diameter in a first axial region adjacent to the housing and a second diameter in a second axial region remote from the housing, the first diameter being larger than the second diameter. A filter device is arranged in the first axial region and the second axial region has a hydraulic connection.

[0004] From DE 100 07 349 A1 a continuous valve for a brake system with a filter device pressed into the hydraulic inlet is known.

[0005] From DE 199 35 602 A1, a spool valve with a housing is known, which has an axial end section on which a connecting sleeve is arranged. The connecting sleeve has a first diameter in a first axial region adjacent to the housing and a second diameter in a second axial region remote from the housing, wherein the first diameter is larger than the second diameter and wherein a filter device is arranged in the first axial region and the second axial region comprises a hydraulic connection. Disclosure of the invention

[0006] The invention relates to a spool valve, in particular for controlling a motor vehicle automatic transmission, with a substantially cylindrical housing having an axial end section. A similarly substantially cylindrical connecting sleeve is arranged on the axial end section of the housing, which has a larger first diameter in a first axial region adjacent to the housing and a smaller second diameter in a second axial region furthest from the housing. A filter device is arranged in the first axial region. The second axial region comprises a hydraulic connection, in particular a so-called "control pressure connection". The spool valve according to the invention is therefore, for example, a pressure control valve.

[0007] Pressure control valves, especially those used to control automatic transmissions, can exhibit hydraulic pressures of up to approximately 20 bar at their inlet and pressure ports. This can generate comparatively high hydraulic forces, which are transmitted to the pressure control valve via O-ring seals located radially on the outside of the spool valve, i.e., coaxially with the housing. For example, the spool valve may contain two O-ring seals with different diameters. The circular area defined by each O-ring seal is crucial for these pressure forces. Therefore, any mounting device used to attach the pressure control valve to the automatic transmission or another section of the vehicle must be able to withstand and transmit these comparatively high forces.

[0008] To minimize these forces, it can be advantageous to keep the diameter of the larger O-ring as small as possible. This minimizes the pressurized area and keeps the hydraulic force low. Conversely, it can be beneficial to maximize the difference in diameter between the larger and smaller O-rings. This can offer advantages in the arrangement and routing of the hydraulic connections on the spool valve. Ultimately, these two requirements for the diameter of the O-ring seals only allow for a comparatively small diameter for the smaller O-ring.

[0009] Despite this limitation, it is possible to design the filter assembly with a comparatively large effective area. This is achieved, among other things, by arranging the filter assembly in the larger first axial section adjacent to the housing. Specifically, the filter assembly is positioned in the section with the larger first diameter. This advantageously allows the effective filtration area to be determined not by the smaller, but by the larger of the two diameters, thus resulting in a correspondingly larger effective area. If required by the design, the second axial section can even be designed with a comparatively small diameter without compromising the effective area of ​​the filter assembly.

[0010] In the slide valve according to the invention, the filter assembly has a radially outer, annular filter section and a radially inner, essentially hat-shaped support section against which a valve spring ("return spring") of the slide valve is supported. This allows the filter assembly to additionally function as a spring retainer for the valve spring, thereby saving space and costs. Although this may reduce the effective area of ​​the filter assembly, the remaining (radially outer) area is still comparatively large thanks to the invention.

[0011] Beneficial further training opportunities are listed in the sub-requirements.

[0012] In particular, according to the invention, the filter device can be arranged on an inner wall section of the connecting sleeve where the first diameter transitions into the second diameter. The filter device is thus supported, as it were, by the shoulder formed by this wall section in the axial direction. This enables particularly simple and precise assembly of the filter device.

[0013] Preferably, the filter assembly is pressed into the connection sleeve. This allows the filter assembly to be easily pre-assembled in the connection sleeve, thus saving costs. This creates a so-called "two-part filter cap" for the filter assembly, where the "filter cap" is formed on one side by the filter assembly and on the other side by the connection sleeve.

[0014] In a preferred embodiment of the invention, the filter device is held between the axial end section of the housing and the aforementioned inner wall section or shoulder of the connecting sleeve between the first and second axial regions. After the connecting sleeve is mounted to the housing—preferably by pressing it radially outward onto the housing—the filter device is positively engaged between the connecting sleeve and the axial end section of the housing and is thus securely positioned during operation of the slide valve.

[0015] In a further embodiment of the slide valve, the transition from the first to the second diameter is at least partially continuous. In particular, this transition can include a radially circumferential "rounding," which not only offers advantages in terms of fluid dynamics but also makes the effective area of ​​the filter device fully usable, especially when it is supported by the shoulder formed between the two diameter sections.

[0016] Furthermore, the filter assembly can be designed essentially as a circular disc ("sieve plate") comprising a radially outer, annular retaining section and a radially inner filter section. This saves installation space and therefore costs. Moreover, this differentiated design of the filter assembly allows for simple and secure press-fitting into the connecting sleeve, as described above.

[0017] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows: Fig. 1. A longitudinal section through a slide valve, which serves for technical explanation; and Fig. 2 a longitudinal section through a slide valve according to the invention.

[0018] The same reference symbols are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

[0019] Fig. Figure 1 shows a longitudinal section through a slide valve 10 not according to the invention, which can be used here for controlling a motor vehicle automatic transmission. The slide valve 10 comprises a stepped cylindrical housing 12, which has an axial end section 14 in the left-hand area of ​​the drawing. The housing 12 and the axial end section 14 are essentially rotationally symmetrical about a longitudinal axis 16. A slide sleeve 18 is arranged radially inside the housing 12 and the axial end section 14, centered along the longitudinal axis 16, and a valve slide 20 is arranged radially inside the slide sleeve 18, centered along the longitudinal axis 16. The slide sleeve 18 is preferably overmolded with a plastic material of the housing 12.

[0020] The valve spool 20 has an axially extending, radially outer circumferential recess 22 in an approximately axially central region. Radially circumferential control edges 24 and 26 are formed on the valve spool 20 at the axial end sections of the recess 22. These control edges interact hydraulically with radial openings 24a, 26a, and 28 of the spool sleeve 18. A radial inlet port 30 and a radial outlet port 32 are formed on the spool valve 10 by means of the radial openings 24a, 26a, and 28 and associated hydraulic channels (without reference numerals, some of which are not shown in the plane of section) in the housing 12, in a manner known per se. A filter fabric 31 is arranged radially outside the inlet port 30, filtering the fluid flowing into the spool valve 10 via the inlet port 30.

[0021] A stepped cylindrical connecting sleeve 34 is arranged radially outside the housing 12 and the axial end section 14 located in the left area of ​​the drawing. The connecting sleeve 34 is essentially rotationally symmetrical and is made of a plastic material. The connecting sleeve 34 has a larger first diameter 38 in a first axial area 36 adjacent to the housing 12 and thus to the right, and a smaller second diameter 42 in a second axial area 40 further away from the housing 12 and thus to the left. Fig. An axial control pressure port 44 of the spool valve 10 is arranged on the left side of the second axial area 40 of the connecting sleeve 34. By means of the inlet port 30, the outlet port 32, and the control pressure port 44, the spool valve 10 can control or regulate the flow of fluid, for example, hydraulic oil for controlling a motor vehicle automatic transmission (not shown), in a manner known per se.

[0022] Furthermore, the connecting sleeve 34 has two radially circumferential outer seals 46 and 48, which in this case are each designed as an O-ring. The connecting sleeve 34 is arranged radially circumferentially on the outside of the housing 12 at three axial sections 50, 52 and 54, forming a fluidically tight seal, and is pressed onto the housing 12 in this case.

[0023] Furthermore, the connecting sleeve 34 comprises a radially circumferential inner wall section 56, at which the first diameter 38 transitions into the second diameter 42, thus forming a kind of step. A filter device 58 for filtering any particles that may be present in the fluid is arranged on the inner wall section 56. The filter device 58 is located in the Fig. 1 is designed as a circular disc (“sieve plate”) and comprises a radially outer annular retaining section 60 and a radially inner sieve-like filter section 62. The filter assembly 58 is held between the axial end section 14 of the housing 12 and the inner shoulder-like wall section 56 of the connecting sleeve 34 by means of the retaining section 60. In this case, the filter assembly 58 is pressed into the connecting sleeve 34 at the annular retaining section 60.

[0024] In the Fig. Figure 1 shows that the transition from the first diameter 38 to the second diameter 42 is continuous in sections, in this case by means of a circumferential rounding 64. As a result, the entire surface of the filter section 62 of the filter device 58 can be used for filtering particles, despite the support on the wall section 56.

[0025] In a right-hand area of ​​the drawing, the slide valve 10 further comprises an electromagnetic actuator (“electromagnet”), which is arranged on the right side of the housing 12 in the drawing and a bracket 66 (right in the Fig. 1) and a substantially cylindrical actuator housing 68. The actuator housing 68 contains, among other things, the following additional elements: a magnetic coil 70, magnetic guides 72 and 74, an axially movable armature 76, a coupling element 78 which axially couples the armature 76 to the valve slide 20, an armature spring 80 designed as a helical spring, and a guide sleeve 82.

[0026] During operation of the slide valve 10, the valve spool 20 can be moved axially by means of the electromagnetic actuator in a manner known per se, thereby enabling control of the fluid and thus of the vehicle's automatic transmission. Depending on the operating state of the slide valve 10, the fluid can flow axially through the filter section 62, whereby any particles are filtered out and thus cannot interfere with the operation of the slide valve 10.

[0027] Fig. Figure 2 shows a longitudinal section through a slide valve 10 according to the invention. In contrast to the Fig. 1 shows the filter device 58 of Fig. 2. Additionally, a radially internal, essentially hat-shaped support section 84 is provided, against which a valve spring 86 ("return spring") of the slide valve 10 is supported. The valve spring 86 exerts a compressive force to the right on an axial end section (without reference numeral) of the valve slide 20, thus counteracting the compressive force of the anchor spring 80. Radially outside the support section 84 are – comparable to the Fig. 1 - the filter section 62 and the holding section 60 are arranged. However, due to the radially inner support section 84, the area of ​​the filter section 62 is smaller than in Fig. 1.

[0028] Operation of the slide valve 10 of Fig. 2 is carried out in a manner similar to the first embodiment of Fig.1 in a comparable manner. Depending on the operating state of the slide valve 10, the filter section 62 is essentially flowed through axially by the fluid, with the fluid flowing radially outside around the support section 84.

Claims

[1] Slide valve (10), in particular for controlling an automatic motor vehicle transmission, with a housing (12) which has an axial end section (14), wherein a connecting sleeve (34) is arranged on the axial end section (14) of the housing (12), which connecting sleeve has a first diameter (38) in a first axial region (36) adjacent to the housing (12) and a second diameter (42) in a second axial region (40) remote from the housing (12), wherein the first diameter (38) is larger than the second diameter (42) and wherein a filter device (58) is arranged in the first axial region (36) and the second axial region (40) comprises a hydraulic connection (44), characterized bythat the filter device (58) has a radially outer annular filter section (62) and a radially inner, substantially hat-shaped support section (84) on which a valve spring (86) of the slide valve (10) is supported. [2] Slide valve (10) according to claim 1, characterized by that the filter device (58) is arranged on an inner wall section (56) of the connecting sleeve (34), at which the first diameter (38) merges into the second diameter (42). [3] Slide valve (10) according to one of the preceding claims, characterized by that the filter device (58) is pressed into the connecting sleeve (34). [4] Slide valve (10) according to claim 2, characterized by that the filter device (58) is held between the axial end portion (14) of the housing (12) and the wall portion (56) of the connecting sleeve (34) between the first and second axial regions (36, 40). [5] Slide valve (10) according to at least one of the preceding claims, characterized by that a transition from the first to the second diameter (38, 42) is carried out continuously at least in sections. [6] Slide valve (10) according to at least one of the preceding claims, characterized by that the filter device (58) is designed substantially as a circular disc which comprises a radially outer annular holding section (60) and a radially inner filter section (62).

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