Slide valve

Abstract

Slide valve (1) with a housing (2) in which at least two connection bores (4, 5, 23) are formed, which open into a slide channel (3), and with a valve slide (8) axially displaceable in the slide channel (3), which has at least two guide sections (9, 10, 24) and at least one control edge (14, 27) for opening or closing a flow cross-section, wherein a first of the connection bores (4) can be operatively connected to a consumer and a second of the connection bores (5) can be connected to a pressure source, wherein at least one of the connection bores (4) is designed as a blind bore (6) and extends beyond the slide channel (3), and that a first of the guide sections (9) having the control edge (14, 27) is associated with the blind bore (6) and has at least one annular groove (15) in its outer surface, characterized in thatthat the annular groove (15) lies at least partially within the blind bore (6) in every position of the valve slide (8) and the diameter (D) of the first connecting bore (4) is larger than the diameter of the slide channel (3).

Description

[0001] The invention relates to a slide valve comprising a housing in which at least two connection bores are formed, which open into a slide channel, and comprising a valve slide which is axially displaceable in the slide channel and has at least two guide sections and at least one control edge for opening or closing a flow cross-section. A first of the connection bores is operatively connected to a consumer and a second of the connection bores is operatively connected to a pressure source. The slide valve is suitable, for example, for controlling an automatic transmission of a motor vehicle. State of the art

[0002] Slide valves of the type mentioned above are known from the prior art. By axially displacing the valve slide in the slide channel, a flow cross-section is opened or closed, or the size of the flow cross-section is determined, by means of at least one control edge. The valve slide is guided in the slide channel by at least two guide sections, which simultaneously interact sealingly with the inner wall of the slide channel. The valve slide is thus constructed like a piston and can be actuated, for example, directly electromagnetically or via a pilot pressure, in particular a hydraulic one. The accuracy of the control edge is important for precise adjustment of the flow cross-section. Furthermore, it is important that the valve slide can be moved with little force and, in particular, has uniform friction over the entire displacement path.To prevent increased friction or jamming of the valve spool due to the hydraulic pressure acting radially on the valve spool, various options for ensuring pressure equalization are known. For example, it is known from the documents DE 35 05 377 A1 or DE 43 24 589 C2 to screw circumferential undercuts into the housing in the area of ​​the connection bores and to provide opposing, aligned bores for the respective connection point and to apply the same pressure to these bores so that the pressure forces are balanced. However, since the pressure or hydraulic medium must be supplied to all bores via appropriate lines, this leads to a complicated and, above all, space-intensive housing design.

[0003] DE 602 22 861 T2 discloses a slide valve having a housing in which at least two connection bores are formed, which open into a slide channel. The slide valve has a valve slide which is axially displaceable in the slide channel and which has at least two guide sections and at least one control edge for opening or closing a flow cross-section, wherein a first of the connection bores is operatively connectable to a consumer and a second of the connection bores is operatively connectable to a pressure source. At least one of the connection bores is designed as a blind bore and extends beyond the slide channel. A guide section having the control edge is assigned to the blind bore and has an annular groove in its outer surface.

[0004] Another slide valve is known from DE 10 2007 039 664 B4. Disclosure of the invention

[0005] The slide valve according to the invention is characterized in that the annular groove lies at least partially in the blind bore or in the region of the blind bore in every position of the valve slide, in particular in every displacement position of the valve slide. This ensures that the radial pressure equalization described above occurs in every position of the valve slide. The extreme positions of the valve slide can preferably be formed by axial stops of the housing, which can be formed by the housing itself or, for example, by a retaining ring introduced into the slide channel. The diameter of the blind bore is larger than the diameter of the slide channel, which means that radial pressure equalization and a large flow cross-section for the inflow and outflow of the fluid on the connection side of the blind bore are quickly achieved.

[0006] In the context of this application, a blind bore is understood to be a bore that is not open on both sides, but ends within the material of the housing. In the present case, the blind bore is designed such that it extends through the spool channel and only ends in the housing beyond the spool channel. This creates a chamber on the side of the spool channel opposite the connection. The first guide section, which is assigned to the blind bore and preferably lies substantially therein, at least when the flow cross-section is closed, has an annular groove in its outer surface. The annular groove is characterized in that it extends over the entire circumference of the component, in this case over the entire circumference of the first guide section of the piston-like valve spool.While the guide section interacts sealingly with the housing, the annular groove provides a channel through which a medium, preferably the hydraulic medium, flows from the connection side of the blind bore to the opposite chamber. This results in the same pressure on the connection side and in the chamber of the blind bore, which acts from opposite sides on the first guide section. Since the blind bore preferably has the same diameter on both sides of the spool channel, radial pressure equalization is ensured because the same pressure forces act on both sides of the valve spool. This advantageous design thus provides a spool valve with low friction forces and is reliably protected against jamming of the valve spool in the spool channel.

[0007] Furthermore, it is preferably provided that the slide valve is designed as a pressure-regulated slide valve. Particularly preferably, a pressure compensation channel is formed in the slide, which comprises at least one radial bore associated with the blind bore, in particular opening into the annular groove, and an axial bore leading from an axial or end face of the slide to the radial bore. The slide channel is typically longer than the valve slide to enable its sliding movement. The means for actuating the valve slide are typically located at one end of the valve slide, while the other end of the valve slide lies freely within the slide channel.Through the pressure equalization channel, which preferably leads to the end face of the free end of the valve spool, pressure equalization takes place between the space formed between the spool and the housing, into which the axial bore opens, and the connection of the blind bore. If the first connection bore is designed as a blind bore, a pressure control valve or a pressure-controlled spool valve is formed. If only one radial bore is provided, this expediently extends through the entire valve spool. Alternatively, two or more radial bores can be provided which are at an angle to one another and meet. If, for example, two radial bores are provided, they are preferably offset by 90° to one another and meet in the axial bore to form the pressure equalization channel.

[0008] According to an alternative embodiment, a pin is arranged in the axial bore of the pressure equalization channel, which pin interacts with the housing at one end. Like the guide sections of the valve spool in the housing, the pin preferably lies radially sealingly in the axial bore. The spool valve is preferably a spool valve controlled by a pilot pressure, so that the valve spool is actuated by the pilot pressure, in particular hydraulic, on the side opposite the chamber.Preferably, the cross-sectional area of ​​the pin that can be moved in the axial bore is smaller than the cross-sectional area of ​​the end face of the valve spool that is acted upon by the pilot pressure, so that the force equilibrium on the valve spool is achieved by a pressure ratio that is inversely proportional to the area ratio, resulting in hydraulic amplification between the pressure in the blind bore and the pilot pressure. As an alternative to a hydraulic pilot pressure, the valve spool can also be actuated directly, for example by an electromagnetic actuator. Here, too, the provision of hydraulic amplification as described above is possible. Particularly preferably, the pin is held in the axial bore by means of an assembly aid element that can preferably be clipped onto the free end of the valve spool, thus providing a loss protection for the pin, which facilitates the assembly of the spool valve.

[0009] Preferably, the first connection bore is designed as a blind hole. Particularly preferably, the first connection bore interacts with the first control edge, wherein—as already mentioned—the first control edge is provided on the first guide section. Thus, the flow cross-section to be opened or closed for the consumer is determined by the overlap position of the first guide section with the first connection bore.

[0010] According to a preferred development of the invention, the housing has a third connection bore, which can be operatively connected to a pressure sink, in particular to a hydraulic tank, and which is located on the side of the first connection bore opposite the second connection bore - viewed in the axial direction. Thus, three connection bores are provided in the housing, which - viewed in the axial direction - are located one behind the other, with the first connection bore located between the second and third connection bores.

[0011] Preferably, the first guide section of the valve spool is arranged between a second guide section and a third guide section and has a second control edge for closing or opening a further flow cross-section, which interacts with the first connection bore. The first guide section thus has both the first and the second control edge, which each interact with the first connection bore. Depending on the direction in which the first guide section is axially displaced by means of the valve spool, either one or the further flow cross-section is opened or closed. The remaining guide sections therefore serve only for guidance and sealing and do not need to have any special control edges, since the respective flow cross-section is determined solely by the first guide section or its position.This simplifies the production of the valve spool and the entire spool valve and reduces manufacturing costs.

[0012] Furthermore, it is preferably provided that the valve spool has a connecting section with a tapered diameter between each guide section, wherein the respective connecting section is located at least partially in the region of the second or third connection bore in every position of the valve spool. If the valve spool is provided with only two guide sections, the connecting section connecting the guide sections is located at least partially in the region of the second connection bore in every position of the valve spool, so that radial pressure equalization always takes place here. The same applies to the embodiment with three guide sections, in which one connecting section is then located in the region of the second connection bore and the other connecting section is located at least partially in the region of the third connection bore in every position of the valve spool, in order to always ensure radial pressure equalization.

[0013] Overall, this provides a cost-effective and easy-to-manufacture slide valve that enables secure displacement of the valve slide within the slide channel through low and, in particular, uniform frictional forces across the displacement path, and requires only a small amount of installation space. By avoiding opposing bores to ensure radial pressure equalization, the housing can be designed more simply overall, with the supply lines to the respective connection bores needing to be provided on only one side of the housing. Furthermore, the provision of the connection bores creates fine control edges, which ensure that only a small flow cross-section is initially released when the valve slide is actuated.

[0014] The invention will be explained in more detail below with reference to the drawings. Fig. 1A and Fig. 1B shows a first embodiment of a slide valve in different operating positions, Fig. 2A and Fig. 2B a second embodiment of the slide valve in different operating positions, Fig. 3A to 3C show a third embodiment of the slide valve in different views, Fig. 4A and Fig. 4B shows a fourth embodiment of the slide valve in different views and Fig. 5 a fifth embodiment of the slide valve in different views.

[0015] Fig. 1A and Fig. 1B show a first embodiment of a slide valve 1 in different operating states. The slide valve 1 comprises a housing 2 having a slide channel 3. The slide channel 3 is designed as a simple bore with a diameter, ensuring simple and cost-effective production of the slide channel 3, which is preferably designed with small tolerances. Two adjacent connection bores 4, 5 open into the slide channel 3, preferably radially. The connection bore 4 can be operatively connected to a consumer, and the connection bore 5 to a pressure source for a hydraulic medium. The first connection bore 4 is designed as a blind hole 6, which extends through the slide channel 3 such that it ends in the material of the housing 2.The blind hole 6 or the first connection hole 4 forms a connection side on one side of the slide channel 3 and a radial pressure compensation chamber 7 on the opposite side of the slide channel 3, the function of which will be discussed in more detail later.

[0016] A valve spool 8 is arranged in the spool channel 3 for axial displacement. The valve spool 8 has a first guide section 9 and a second guide section 10, which are rigidly connected to one another by a connecting section 11. Preferably, the guide sections 9 and 10 are each formed integrally with the connecting section 11. The guide sections 9 and 10 have a diameter that essentially corresponds to the inner diameter of the spool channel 3, so that the guide sections 9 and 10 are located in the spool channel 3 in a guiding and radially sealing manner. The guide sections 9 and 10 are designed with respect to the connecting bores 4 and 5 such that they are spaced further apart from one another than – viewed in the axial direction – the connecting bores 4 and 5.The slide channel 3 is open at one end and has an axial stop for the valve slide 8 at its other end, which is formed by the housing 2 and limits the maximum stroke of the valve slide 8 in the direction of arrow 12. A bore with a tapered diameter adjoins the axial stop, so that a space 22 is formed between the valve slide 8 and the housing 2. In the embodiment shown in . Fig. In the extreme state shown in Figure 1A, in which the valve spool 8 is displaced in the direction of arrow 12 up to the axial stop of the housing 2, the connecting bores 4 and 5 are fluidly connected to one another. The connecting section 11 has a reduced diameter relative to the guide sections 9 and 10, so that an annular chamber 13 is formed between the guide sections 9 and 10, which, in the extreme state shown, is connected to both connecting bores 4 and 5.

[0017] A first control edge 14 is provided on the first guide section 9, which interacts with the first connecting bore 4 to open or close a flow cross-section. As shown, a flow cross-section between the connecting bore 4 and the slide channel 3 is adjusted in a known manner according to the axial position of the valve slide 8.

[0018] The guide section 9 further comprises an annular groove 15 formed in its outer surface such that, in every position of the valve spool 8, it is located at least partially in the blind bore 6 or in the first connection bore 4. This ensures a constant fluidic connection between the connection side of the blind bore 6 and the radial pressure compensation chamber 7. The annular groove 15 and the radial pressure compensation chamber 7 thus apply the same pressure to the guide section 9 from two opposite sides. In other words, the annular groove 15 and the radial pressure compensation chamber 7 ensure radial pressure compensation for the valve spool 8 and in particular for the guide section 9.

[0019] If the valve slide 8 is moved in the opposite direction to the arrow 12, the Fig. 1A released flow cross-section reduced, as in Fig. 1B, or closed by further displacement. Even when the flow cross-section is closed, the annular groove 15 and the radial pressure compensation chamber 7 ensure radial pressure compensation for the guide section 9. The advantageous design of the slide valve 1 effectively prevents, in particular, tilting of the valve slide 8 in the slide channel 3. Furthermore, the frictional forces when moving the valve slide 8 are kept low over the entire displacement path or stroke. By designing the connection bore 4 as a blind hole 6, which extends beyond the slide channel 3, it is not necessary, in contrast to previously conventional solutions, to provide opposing bores on both sides of the slide channel 3, to which a supply line must then also be laid.Thus, the installation space requirement and the manufacturing effort of the present slide valve 1 are reduced compared to conventional solutions.

[0020] In the present exemplary embodiment, the slide channel 3 is tightly closed on the side opposite the chamber 22 by a plug 16, wherein a compression spring 17 is pretensioned between the plug and the valve slide 8, which compression spring 17 is preferably designed as a helical spring and urges the valve slide 8 into its extreme position in the direction of arrow 12. In the area of ​​the compression spring 17, the slide channel 3 is depressurized in a known manner by means of bores, channels or the like, or is connected to a depressurized level, in particular to the tank, so that no pressure can build up in the slide channel 3 in the area of ​​the compression spring 17 due to leakage at the guide section 10. Alternatively, it is also conceivable to actuate the valve slide 8 by means of a magnetic or hydraulic pilot pressure.

[0021] Furthermore, a pressure equalization channel 18 is provided in the valve slide 8, which is formed by at least one radial bore 19 through the guide section 9 and an axial bore 20 opening into the radial bore 19. The axial bore 20 leads from the radial bore 19 to an end face 21 of the valve spool 8 or the guide section 9 and opens there into a space 22 formed by the housing 2 and the guide section 9. The radial bore 19 extends through the entire valve spool 8 in the region of the annular groove 15 of the guide section 9. Thus, the space 22 is always connected to the connection bore 4 via the pressure equalization channel 18. The pressure which is guided from the connection bore 5 via the chamber 13 to the connection bore 4 reaches the space 22 via the pressure equalization channel 18 and generates a pressure force here which is opposite to the force of the compression spring 17.If this pressure force exceeds the force of the compression spring 17, the guide section 9 at the control edge 14 closes the connection bore 4. If the pressure drops, for example due to leakage at the connection bore 4, the pressure in the chamber 22 drops, whereby the pressure force is reduced and the valve spool 3 is displaced in the direction of the arrow 12 by the force of the compression spring 17, thereby opening the connection from the connection bore 4 to the connection bore 5 at the control edge 14 and increasing the pressure in the connection bore 4 again. This results in a pressure-controlled spool valve 1.

[0022] Fig. 2A and Fig. 2B show a second embodiment of the slide valve 1. Elements known from the previous embodiments are provided with the same reference numerals below, so reference is made to the respective preceding description. The following will primarily address the differences.

[0023] In the present exemplary embodiment, the housing 2 is provided with a third connection bore 23, which is formed on the side of the connection bore 4 opposite the connection bore 5, such that the connection bore 4 lies between the connection bores 5 and 23. Furthermore, the valve spool 8 has a third guide section 24, which is connected, in particular integrally, to the guide section 9 via a connecting section 25. The axial bore 18 extends from the at least one radial bore 19 through the connecting section 25 and the guide section 24. The connection 4 is thus still fluidly connected to the chamber 22 via the pressure equalization channel 18. In this case, however, the end face 21 is provided on the guide section 24.Like the connecting section 11, the connecting section 25 also has a smaller diameter than the guide sections 24 and 9, so that an annular chamber 26 is formed between the guide sections 24 and 9. As previously described, the maximum displacement path of the valve slide 8 is limited at one end by a stop of the housing and at the other end by a retaining ring 28 in the slide channel 3.

[0024] The guide section 9 further has a second control edge 27, which interacts with the blind bore 6 to open or close a further flow cross-section. The valve spool 8 and in particular the annular groove 15 are arranged or designed such that the annular groove 15 is always located in the region of the blind bore 6, thus always ensuring a fluidic connection from the connection side to the pressure chamber 7. The guide sections 10 and 24 are arranged at a distance from the guide section 9 such that, in every operating position of the valve spool 8, the chambers 13 and 26 are connected to the connection bores 23 and 25, respectively.

[0025] An end face 29, which is provided at the end of the valve spool 8 opposite the end face 21, is connected to a chamber 30 in which a pilot pressure can be set, which is preferably controlled by an electromagnetically actuated valve.

[0026] In the Fig. In the operating position shown in Figure 2A, the connection bore 4 is hydraulically connected to the connection bore 23 via the chamber 26 and to the chamber 22 via the pressure equalization channel 18. The connection bore 23 can be operatively connected to the pressure sink, in particular to a hydraulic tank. Thus, the connection bore 4 and the chamber 22 are connected to the tank, i.e., depressurized. In the present case, ambient pressure prevails in the chamber 30. The pressure of the pressure source present in the connection bore 5 and in the chamber 13 is sealed by the guide sections 9 and 10 in the spool channel 3 by means of the respective gap seal. Leakage via the gap seals of the guide sections 9 and 10 can occur to the tank via the connection bore 23. Since the surfaces in the chamber 13 are hydraulically balanced, the valve spool 8 does not move due to the applied pressure from the pressure source.

[0027] If the pilot pressure in chamber 30 is increased by actuating the electromagnetic valve, the resulting pressure force moves the valve spool 8 to the left in the direction of arrow 12. In this case, the control edge 27 of the guide section 9 first separates the connecting bore 4 from the chamber 26. Upon further movement in the direction of arrow 12, the guide section 9 moves with its first control edge 14 in the area of ​​the connecting bore 4 and thereby connects the connecting bore 4 with the chamber 13, as shown in Fig. 2B. This connects the pressure source to the consumer, and the pressure in the connection bore 4 increases in line with the pressure provided by the pressure source. At the same time, this pressure is conducted via the pressure equalization channel 18 into the chamber 22, so that pressure is also built up there. The pressure in the chamber 22 now acts on the end face 21 of the guide section 24 and generates a force that displaces the valve spool 8 in the opposite direction to the arrow 12 if the force exerted by the pilot pressure in the chamber 30 on the end face 29 of the guide section 10 is lower. Thus, the connection between the connection bore 4 and the chamber 13 is closed again.

[0028] If, for example, the pressure in the connection bore 4 is reduced due to leakage, the pressure in the chamber 22 is also reduced, which leads to an excess of force on the valve spool 8 and moves it again in the direction of arrow 12. This opens the flow cross-section between the connection bore 4 and the chamber 13 again and creates a connection to the connection bore 5 or the pressure source, and the pressure in the connection bore 4 increases again. If, on the other hand, the pilot pressure in the chamber 30 decreases, this results in an excess of force opposite to the direction of arrow 12, which opens the flow cross-section between the connection bore 4 and the chamber 26 and equalizes the pressure between the connection bore 4 and the tank.The opening and closing of the further flow cross-section to the chamber 26 or the flow cross-section to the chamber 13 thus results in a pressure regulation of the pressure in the connection bore 4. A regulated pressure is thus made available at the connection bore 4 as the working pressure.

[0029] The guide section 9 and the connection bore 4 form all of the control edges 14, 27 of the slide valve 1. The guide sections 10 and 24 and the connection bores 5 and 23, however, do not need to be provided with control edges, so that during production, tight tolerances only need to be observed for the connection bore 4 and the control edges 14 and 17 on the guide section 9, which simplifies production and reduces costs. Since when the flow cross-sections are released due to the circular shape of the connection bore 4, only a small circular section area is initially released and the flow cross-section only increases significantly with a larger stroke, the function of fine control edges is achieved without the need for additional design or manufacturing measures.

[0030] The pressure in the connecting bore 4 is constantly balanced by the annular groove 15 and the radial pressure compensation chamber 7. This pressure compensation ensures that the pressure in the connecting bore 4 does not act one-sidedly on the valve spool 8, thus preventing tilting or an increased normal force, and thus increased friction, due to the resulting pressure force. The advantageous design with the annular groove 15, which is located in the area of ​​the blind bore 6 in every operating position of the valve spool 8, ensures a simple and cost-effective pressure compensation function.

[0031] Based on Fig. 2A and Fig. 2B also explains the conditions for the position of the annular groove 15 in more detail. As in Fig. 2A, the annular groove 15 and the guide section 9 must be dimensioned such that the distance s1 of the control edge 27 to the boundary of the connection bore 4 is greater than zero when the valve spool 8 is in stop against the retaining ring 28. In order to reliably ensure pressure control, a hydraulic connection from the connection bore 4 to the chamber 22 must always be ensured. For this purpose, the radial bore 19 expediently opens into the annular groove 15. In particular, in its other extreme position, when the valve spool 8 is at the stop of the housing, as in Fig. 2B, the bore diameter D of the connecting bore 4 must be dimensioned such that it is larger than the sum of the width s2 of the flow cross-section formed between the connecting bore 4 and the annular groove 15 and the width I of the remaining area of ​​the guide section 9 from the annular groove 15 to the control edge 14, so that: D > I + s2, with s2 > 0

[0032] Another example is in Fig. 3A to 3C. While the Fig. 3A shows the slide valve 1 as before in a simplified longitudinal section view, the Fig. 3B is a plan view of the housing showing the connection holes 4, 5 and 23, and the Fig. 3C shows a cross-sectional view through the slide valve 1 in the area of ​​the radial bore 19. According to the third embodiment, the diameter of the connecting bore 4 is selected to be larger than the diameter of the bore forming the slide channel 3. This significantly increases the space for pressure equalization in the area of ​​the annular groove 15 and also the flow cross sections available for the inflow and outflow of the fluid in the direction of the connecting bore 4, as can be seen from the additional space areas 31a and 31b in Fig. 3B. This allows for an improved pressure equalization function. The filling or emptying of the connection bore 4 and, preferably, the clutch of the motor vehicle connected to the connection bore 4 is improved and, in particular, accelerated by these large flow cross-sections. Rapid filling and emptying, or the rapid pressure buildup and reduction in the connection bore 4, is particularly important for the function of the slide valve in the control of automatic transmissions for motor vehicles.

[0033] Fig. 4A and Fig. 4B show a further embodiment of the slide valve 1, which differs in particular from the first embodiment in that the third connection bore 23 is provided, but no third guide section 24. Fig. 4A shows the slide valve 1 again in a longitudinal section, while the Fig. 4B shows a cross-section through the spool valve 1 along the line BB. In the axial bore 20 of the pressure equalization channel 18, a pin 32 is also axially displaceably mounted, which, in conjunction with the axial bore 20, forms a gap seal between the connection bore 4 and the chamber 22, into which the connection bore 23 also opens. Since one end face of the pin 32 in the chamber 22 is subjected to ambient pressure or tank pressure and / or rests against the housing, and the other end face of the pin 32 is subjected to the pressure in the connection bore 4, a pressure force is generated on the valve spool 8 opposite to the direction of arrow 12, which pressure can be calculated from the pressure in the connection bore 4 or in the radial bore 19 multiplied by the cross-sectional area of ​​the pin 32.Since the cross-sectional area of ​​pin 32 is smaller than the cross-sectional area of ​​the guide section 10 of valve spool 8, the force equilibrium on valve spool 8 is achieved by a pressure ratio inversely proportional to the area ratio. This results in a hydraulic amplification between the pressure in connection bore 4 and the pressure in chamber 30.

[0034] This hydraulic boost function makes it possible, in particular, to deflect or actuate the valve spool 8 not only by a pilot pressure in chamber 30 regulated by a solenoid valve, but also by an electromagnetic actuator acting directly on the valve spool, i.e., direct control of the valve spool 8 is also possible. For this purpose, a magnetic armature preferably exerts a force directly on the end face 29, analogous to the pressure force of the pilot pressure. In this case, the chamber 30 is then connected to a pressureless level (tank) so that no pressure can build up in the chamber 10 due to leakage at the guide section 10, which would create a disturbance to the magnetic force. This embodiment can of course also be used for the spool valves without hydraulic boost described in the other exemplary embodiments.

[0035] Fig. 5 shows a fifth embodiment of the slide valve 1, which differs from the previous embodiment in that an auxiliary assembly element 33 is provided. The auxiliary assembly element is cup-shaped and can be clipped onto the free end 34 of the valve slide 8 with some play. For this purpose, the free end of the valve slide 8 has a radial locking projection 35 and the auxiliary assembly element has a corresponding radial counter-locking projection 36. Preferably, the auxiliary assembly element 33 is elastically deformable at least in the region of the counter-locking projection 36, so that the counter-locking projection 36 can be pushed over the locking projection 35 and reaches a rear engagement position behind it. The auxiliary assembly element 33 functions as a loss protection for the pin 32 before and during assembly of the valve slide 8. The valve slide 8, the pin 32, and the auxiliary assembly element 33 form a pre-assembly group that is inserted into the slide channel 3.The assembly aid 33 is preferably designed as a plastic injection-molded part. When inserted into the slide channel 3, the assembly aid 33 is inserted into a region 37 with a reduced bore diameter and is pushed over the free end face of the valve slide 8 to the bottom of the slide channel 3, as shown in FIG. Fig.5, pushed or positioned. The assembly aid 33 and the area 37 have diameters that form a press fit, so that the assembly aid 33 is non-positively fixed in the position shown. Due to the play between the assembly aid 33 and the valve spool 8, the valve spool 8 can move axially in the manner described above without frictional forces occurring between the assembly aid 33 and the valve spool 8. Therefore, any influence of the assembly aid 33 on the function of the valve spool 8 is excluded. The axial play is determined by the length of the end of the valve spool 8 protruding from the guide section 9 and the depth of the cup-shaped assembly aid 33.

[0036] The slide valve 1 described here in the different embodiments is preferably used in automatic transmissions of motor vehicles, in particular in electro-hydraulic control modules thereof.

Claims

[1] Slide valve (1) with a housing (2) in which at least two connection bores (4, 5, 23) are formed, which open into a slide channel (3), and with a valve slide (8) which is axially displaceable in the slide channel (3) and which has at least two guide sections (9, 10, 24) and at least one control edge (14, 27) for opening or closing a flow cross-section, wherein a first of the connection bores (4) is operatively connectable to a consumer and a second of the connection bores (5) is operatively connectable to a pressure source, wherein at least one of the connection bores (4) is designed as a blind bore (6) and extends beyond the slide channel (3), and that a first of the guide sections (9) having the control edge (14, 27) is assigned to the blind bore (6) and has at least one annular groove (15) in its outer surface, characterized bythat the annular groove (15) lies at least partially in the blind hole (6) in every position of the valve slide (8) and the diameter (D) of the first connection bore (4) is larger than the diameter of the slide channel (3). [2] Slide valve (1) according to one of the preceding claims, characterized by a pressure equalization channel (18) formed in the valve slide (8), which comprises at least one radial bore (19) associated with the first connection bore (4) and opening into the annular groove (15) and an axial bore (20) leading from an end face (21) of the valve slide (8) to the radial bore (19). [3] Slide valve (1) according to claim 2, characterized by that the axial bore (20) of the valve slide (8) opens into a space (22) of the housing (2) associated with the end face (21). [4] Slide valve (1) according to one of claims 2 or 3, characterized bythat a pin (32) is arranged in the axial bore (20) so as to be axially displaceable and which cooperates at one end with the housing (2). [5] Slide valve (1) according to one of the preceding claims, characterized by that the first connection bore (4) is designed as the blind hole (6). [6] Slide valve (1) according to one of the preceding claims, characterized by that the housing (2) has a third connection bore (23) which can be operatively connected to a pressure sink and which is located on the side of the first connection bore (4) opposite the second connection bore (5) - viewed in the axial direction. [7] Slide valve (1) according to one of the preceding claims, characterized bythat the first guide section (9) of the valve slide (8) is arranged between a second guide section (10) and a third guide section (24) and has a second control edge (27) for closing or releasing a further flow cross-section, which second control edge cooperates with the first connection bore (4). [8] Slide valve (1) according to one of the preceding claims, characterized by that the valve slide (8) has a connecting section (11, 25) tapered in diameter between the guide sections (9, 10, 24), wherein the respective connecting section (11, 23) lies at least partially in the region of the second or third connection bore (5, 23) in each position of the valve slide (8). [9] Slide valve (1) according to one of the preceding claims, characterized by that the slide valve (1) is suitable for controlling an automatic transmission of a motor vehicle.

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