Pressure medium switching valve

Abstract

Pressure medium switching valve (2) of an automatic transmission of a motor vehicle, comprising a valve plate (4) on which a first housing part (8) is arranged with an intermediate plate (6) in between, wherein a channel-shaped valve interior (12) is formed in the valve plate (4) arranged perpendicular to the intermediate plate (6), wherein a first valve seat (14) formed on the intermediate plate (6) is assigned to the intermediate plate-side end of the valve interior (12), wherein the first valve seat (14) is connected to a first controllable pressure medium line (16) formed in the first housing part (8), wherein a second valve seat (18) is formed at the valve plate-side end of the valve interior (12) and is connected to a second controllable pressure medium line (20) formed in the valve plate (4),wherein a third pressure medium line (22) branches off axially from the valve interior (12) between the first valve seat (14) and the second valve seat (18), and wherein a valve body (24) is arranged in the valve interior (12) which is axially freely movable between the first valve seat (14) and the second valve seat (18) and which interacts with the two valve seats (14, 18), characterized in that the second pressure medium line (20) is formed by an open channel which is formed above the second valve seat (18) in the valve plate (4), and which is covered by a second housing part (10) attached to the valve plate (4) to form a closed channel.

Description

The invention relates to a pressure-medium switching valve in an automatic transmission of a motor vehicle, comprising a valve plate on which a first housing part is arranged with an intermediate plate in between, wherein a channel-shaped valve interior is formed in the valve plate, arranged perpendicularly to the intermediate plate, wherein a first valve seat formed on the intermediate plate is assigned to the intermediate plate-side end of the valve interior, wherein the first valve seat is connected to a first controllable pressure medium line formed in the first housing part, wherein a second valve seat is formed at the valve plate-side end of the valve interior, which is connected to a second controllable pressure medium line formed in the valve plate, and wherein a third pressure medium line branches off axially from the valve interior between the first valve seat and the second valve seat.and in which a valve body is arranged in the valve interior between the first valve seat and the second valve seat, which is axially freely movable and interacts with the two valve seats. Switching valves of this type are used, for example, to control an emergency stop function or to safeguard a holding function in automatic transmissions of motor vehicles. Compared to ball rocker switching valves, which are also commonly used, they are characterized by their simple design, reliable and rapid switching, and high level of sealing. Valve balls are predominantly used as the valve body. From DE 103 32 209 A1, a switching valve of the type mentioned in the preamble of claim 1 is known. A housing part, which interacts with the valve plate, is arranged on a valve plate with an intermediate plate. A channel-shaped valve interior, designated as a control channel, is formed in the valve plate, to which three pressure medium lines are connected. A first valve seat formed on the intermediate plate is associated with the end of the control channel on the intermediate plate side, and this seat is connected to a first pressure medium line. At its end on the valve plate side, the control channel has a second valve seat, which is connected to a second controllable pressure medium line. A third pressure medium line branches off axially from the control channel between the two valve seats. The second pressure medium line consists of a first section coaxial with the control channel, a second section running transversely to it and inserted from the outside as a blind bore into the valve plate, a third section intersecting the second section and running parallel to the control channel, and a channel opening perpendicularly into this third section. The latter channel must be connected to other housing components (not shown) that are connected to a pressure medium source. The blind-bore second section of the second pressure medium line is sealed from the outside by a cover plate downstream of the branch to the third section. This channel configuration is evidently complex in terms of design and manufacturing, and therefore expensive to produce. Against this background, the invention is based on the objective of creating a pressure medium switching valve of the type mentioned in the preamble of claim 1, which is structurally and structurally much simpler and therefore more cost-effective to manufacture. The solution to this problem arises from the features of the main claim, while advantageous embodiments and further developments of the invention can be found in the dependent claims. The invention is based on the understanding that where two components abut each other over a flat surface, a groove formed in one of the contact surfaces and covered by the other contact surface can form a closed channel or conduit. Such an open groove is particularly easy and inexpensive to manufacture. The invention relates to a pressure-medium switching valve for an automatic transmission of a motor vehicle, comprising a valve plate on which a first housing part is arranged with an intermediate plate in between, wherein a channel-shaped valve interior is formed in the valve plate, arranged perpendicularly to the intermediate plate, wherein a first valve seat formed on the intermediate plate is assigned to the intermediate plate-side end of the valve interior, wherein the first valve seat is connected to a first controllable pressure medium line formed in the first housing part, wherein a second valve seat is formed at the valve plate-side end of the valve interior, which is connected to a second controllable pressure medium line formed in the valve plate, and wherein a third pressure medium line branches off axially from the valve interior between the first valve seat and the second valve seat.and in which a valve body is arranged in the valve interior between the first valve seat and the second valve seat, which is axially freely movable and interacts with the two valve seats. To solve the problem posed, this pressure medium switching valve is designed so that the second pressure medium line is formed by an open channel that is formed above the second valve seat in the valve plate, and which is covered by a second housing part attached to the valve plate to form a closed channel. In a preferred embodiment of this pressure medium switching valve, the valve plate is made of a cast material, wherein the valve interior containing the valve body and the first valve seat are subsequently machined to ensure precise guidance and a precise, tight fit of the valve body. According to a further embodiment, the second valve seat formed on the intermediate sheet is created by punching and embossing, whereby punching and embossing of sheet material are also simple and inexpensive process steps. The channel-shaped valve interior is preferably mounted with a vertical axis alignment relative to a horizontal position of the motor vehicle, so that the valve body rests against a valve seat due to gravity in the rest state, thereby giving the switching valve a defined initial control position. The valve body can have any suitable shape, for example a cylinder. In a preferred embodiment, however, the valve body is a valve ball. The invention is further explained below with reference to an exemplary embodiment. A drawing is attached to the description, which shows a schematic longitudinal section through a pressure medium switching valve with the features of the invention. The switching valve 2 shown in Fig. 1 comprises a valve plate 4, a valve housing 8 arranged thereon with an intermediate plate 6, and a gear housing 10 also arranged on the valve plate 4. The valve housing 8 is referred to in claim 1 as the first housing part and the gear housing 10 as the second housing part. The valve plate 4 has a channel-shaped valve chamber 12 with a circular cross-section, which is oriented perpendicularly to the intermediate plate 6. A first valve seat 14, formed on the intermediate plate 6, is associated with the axial end of the valve chamber 12 on the intermediate plate side and is connected to a first pressure medium line 16 formed in the valve housing 8, which is controllable via the switching valve 2. A second valve seat 18 is formed at the axial end of the valve chamber 12 on the valve plate side and is connected to a second pressure medium line 20, which is also controllable via the switching valve 2. A third pressure medium line 22 branches off axially from the valve interior 12 between the two valve seats 14, 18. A valve body 24, designed here as a valve ball, is arranged in the valve interior 12 and is axially freely movable between the first valve seat 14 and the second valve seat 18, cooperating with these valve seats 14, 18. As the two directional arrows 26 and 28 show, the first pressure medium line 16 and the second pressure medium line 20 serve as supply lines that deliver pressure medium at different pressures. Depending on which of the two pressure medium lines 16, 20 is pressurized, pressure medium at a higher or lower pressure is directed via the switching valve 2 into the third pressure medium line 22, which is connected, for example, to an emergency stop valve. As the figure shows, the second pressure medium line 20 is initially designed as an open channel in a contact surface 32 of the valve plate 4, the channel being covered by a mounting surface 30 of the gearbox housing 10, so that the pressure medium line 20 is designed as a closed channel overall. Reference sign 2 Switching valve 4 Valve plate 6 Intermediate plate 8 Valve housing, first housing part 10 Gearbox housing, second housing part 12 Valve interior 14 First valve seat 16 First hydraulic line 18 Second valve seat 20 Second hydraulic line 22 Third hydraulic line 24 Valve body, valve ball 26 Directional arrow 28 Directional arrow 30 Mounting surface of the gearbox housing 32 Contact surface of the valve plate

Claims

Pressure medium switching valve (2) of an automatic transmission of a motor vehicle, comprising a valve plate (4) on which a first housing part (8) is arranged with an intermediate plate (6) in between, wherein a channel-shaped valve interior (12) is formed in the valve plate (4) arranged perpendicular to the intermediate plate (6), wherein a first valve seat (14) formed on the intermediate plate (6) is assigned to the intermediate plate-side end of the valve interior (12), wherein the first valve seat (14) is connected to a first controllable pressure medium line (16) formed in the first housing part (8), wherein a second valve seat (18) is formed at the valve plate-side end of the valve interior (12) and is connected to a second controllable pressure medium line (20) formed in the valve plate (4),wherein a third pressure medium line (22) branches off axially from the valve interior (12) between the first valve seat (14) and the second valve seat (18), and wherein a valve body (24) is arranged in the valve interior (12) which is axially freely movable between the first valve seat (14) and the second valve seat (18) and which interacts with the two valve seats (14, 18), characterized in that the second pressure medium line (20) is formed by an open channel which is formed above the second valve seat (18) in the valve plate (4), and which is covered by a second housing part (10) attached to the valve plate (4) to form a closed channel. Switching valve according to claim 1, characterized in that the valve plate (4) is made of a cast material, and that the valve interior (12) containing the valve body (24) and the first valve seat (14) are machined. Switching valve according to claim 1 or 2, characterized in that the first valve seat (14) formed on the intermediate plate (6) is formed by punching and embossing. Switching valve according to one of claims 1 to 3, characterized in that the channel-shaped valve interior (12) is mounted with a vertical axis alignment with respect to a horizontal position of the motor vehicle. Switching valve according to one of claims 1 to 4, characterized in that the valve body (24) is a valve ball.

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