WO2001004497A1

WO2001004497A1 - Precontrolled sliding valve

Info

Publication number: WO2001004497A1
Application number: PCT/DE2000/002014
Authority: WO
Inventors: Horst Rott
Original assignee: Mannesmann Rexroth Ag
Priority date: 1999-07-09
Filing date: 2000-06-20
Publication date: 2001-01-18
Also published as: DE19932139B4; DE19932139A1

Abstract

Disclosed is a precontrolled distributing valve configured as a sliding valve. The sliding valve (40) is provided with different surfaces, whereby it can be moved into a control position as a result of the force arising from the difference between said surfaces when pressure is applied to both front surfaces.

Description

description

Pilot operated slide valve

The invention relates to a slide valve according to the preamble of claim 1 and a valve slide provided therefor.

Such slide valves can be designed, for example, as a 3/2-way valve in order to connect a consumer connected to a work connection, for example a lifting cylinder, to a pump or a tank.

In such a solution, known for example from the data sheet "DMDA Data Sheet (4/99) # 999-901-185" from Sunhydraulik GbmH, the valve slide is guided in a cartridge-like housing, the pressure connection being designed as an axial connection during the The working connection and the tank connection are formed by radial bore stars in the valve housing. The valve slide is provided on its outer circumference with circumferential control edges, so that the three connections (pressure connection, working connection, tank connection) can be connected to one another by its axial displacement. Depending on the design of the valve slide, the working connection can be connected to the tank connection, to the pump connection or the pump connection to the tank connection in a basic position.

It is problematic that such 3/2-way valves are only suitable for the control of relatively small flow rates because of the considerable flow forces with larger flow rates.

The invention has for its object to provide a slide valve and a suitable valve slide, which can also be used at high flow rates.

This object is achieved by a slide valve with the features of claim 1 and a valve slide according to claim 11. According to the invention, the valve slide is designed with a difference in area, the rear end face of the valve slide, which is designed with a larger area, being acted upon by a pilot valve arrangement with approximately the same pressure as the other end face, so that the valve slide is caused by the force resultant in one Switch position is moved. Another switching position can be set in which the pressure space adjacent to the larger end face is relieved via the pilot valve arrangement, so that the valve slide is moved by the pressure acting on its smaller end face into the other switching position.

By means of the hydraulic actuation of the slide valve controlled by the pilot control, large flow forces are also overcome, so that the slide valve can be brought into its display positions and held therein even with very large flow rates.

The end section of the valve slide with the larger end face can be delimited, for example, by a radial collar or by a guide ring which is placed on an end section of the valve slide.

The first-mentioned solution with the radial collar formed in one piece on the valve slide has the disadvantage that the valve slide has to be turned off during manufacture over a large axial length, so that a considerable manufacturing outlay is required.

In order to avoid jamming of such a valve slide having a considerable axial length in the valve bore, it is necessary to carry out the graduation of the valve slide forming the area difference and the corresponding guide sections of the valve bore with a small tolerance. This disadvantage can be eliminated by the formation of the larger end face via the aforementioned guide ring. Together with the associated end section of the valve slide, the guide ring forms the larger end face, the outer circumference of the guide ring being guided in a radially widened part of the valve bore. When manufacturing the slide valve according to the invention, the outer diameter of the valve slide must then be adapted essentially only to the smaller diameter of the valve bore, while the outer diameter of the guide ring is adapted to the larger diameter of the valve bore.

Any manufacturing tolerances can then be compensated for in the sealing gap between the inner circumferential surface of the guide ring and the outer circumference of the end section of the valve slide which plunges into it. Such tolerances can be compensated for, for example, by means of an elastic seal which is inserted into the sealing gap between the guide ring and the slide valve.

Because of the simpler manufacture, it is preferred to use this seal in a circumferential groove of the valve slide.

By extending the guide ring beyond the valve slide, the ring end face of the guide ring can be used as a stop surface for the valve slide to limit a switching position. The axial fixing in the stop direction takes place via a radial shoulder of the guide ring, which rests on the adjacent end face of the valve slide. In addition, the guide ring can be fixed axially on the valve slide via a locking ring.

A particularly compact design is obtained when a compression spring acting on the valve slide engages the ring face of the guide ring on the valve side. This means that in this variant the compression spring engages around an axial section of the valve slide and is supported on a housing shoulder. In a particularly preferred variant, the valve slide is provided with an axial throttle bore, via which pressure medium can be guided from the pressure connection to the larger end face delimited by the guide ring. This axial throttle bore opens into a pilot valve seat, which can be closed by a valve body of a pilot valve. In the closed position, a connection is made from the valve body between the pressure space adjacent to the larger end face with the tank connection, so that the rear of the valve slide is relieved and this is brought into its other switching position by the pressure at the pressure connection P.

A two-part design of the valve housing enables easy machining of the guide surfaces.

The construction according to the invention can be used particularly advantageously in 3/2-way slide valves with a pump connection, a tank connection and a pressure connection.

A compression spring can apply a force to the valve spool, which acts parallel or opposite to the pressure force resulting on the end faces.

Other advantageous developments of the invention are the subject of the further subclaims.

Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Figure 1 is a circuit diagram of a first embodiment of a pilot operated 3/2-way slide valve.

FIG. 2 shows a section through a slide valve according to FIG. 1 in a first switching position;

3 shows the slide valve from FIG. 2 in a second switching position; 4, 5 two further embodiments of a pilot operated 3/2-way slide valve and

Figure 6 shows an embodiment with a one-piece valve slide.

Fig. 1 shows a hydraulic circuit diagram of the valve assembly according to the invention with a 3/2-way valve 2 which is controlled via a pilot valve 4.

The directional control valve 2, which is designed as a valve, has a pressure connection P, a tank or tank connection T and a working connection A. The pressure connection P is connected via a pressure line 6 to a hydraulic pump 8. The consumer connection A is connected to an unillustrated consumer via an indicated working line 10, while the tank connection T is connected to a tank T via a return line 12. In the switching position marked with (a), the pressure port P is connected to the work port A, the tank port T is shut off. In the other switching position (b), the connections A and T are connected to one another so that the pressure medium can flow back from the consumer to the tank T. The pressure port P is then shut off.

The pilot valve 4 has a pump connection R, a return connection U and a control connection X. The latter is guided via a control line 14 to that end face of a valve slide of the directional control valve 2, via which pressure can be applied in the direction of the switching position marked with (b). The end face of the valve slide acting in the opposite direction (switching position (a)) is acted upon by the pressure in the pressure line 6 and the force of a compression spring 16.

The pilot valve 4 is biased via a pilot spring 18 into a switching position marked with (c), in which the control connection X is connected to the pump connection R and which with the Return line 12 connected return port U is blocked. By actuating an electromagnet 20, the pilot valve 4 can be brought into the switching position labeled (d), in which the pump connection R is shut off and the control connection X is connected to the return connection U, so that the slide valve in the switching position (b) of the directional control valve acting end face is relieved.

As will be described in more detail below, the end faces of the directional control valve spool are designed with a surface difference, so that when the same pressure is applied to the two end faces, a force resultant acting against the force of the compression spring 16 forces the directional control valve spool into the with the Switching position (b) shown pre-tensioned.

This means that when the electromagnet 20 is not actuated, the pressure in the pump line 6 is present on both end faces of the directional valve valve slide, so that it is biased against the force of the compression spring 16 into the basic position identified by (b) and by the consumer via the connections A and T flows off with pressure medium. When the electromagnet 20 is energized, the pilot valve 4 is brought into the switching position marked with (d), so that the pressure medium can flow out of the control line 14 into the tank T - the right-hand end face of the directional control valve -valve slide is relieved in FIG. 1, so that this is brought from the basic position (b) to the switching position marked (a), in which the working port A is connected to the pressure port P. Pressure medium can then flow to the consumer, for example a hydraulic cylinder.

2 and 3, a section through a valve assembly 1 is shown, with which the circuit shown in Fig. 1 is realized.

The valve arrangement 1 shown in FIG. 1 is designed as a built-in valve which is inserted into a stepped receiving bore 22 of a valve block 24. In the receiving bore 22 of the valve block

24 also open the pressure port P, the working port A and the tank connection T, the latter two connections A, T being radial connections, while the pressure connection P is an axial connection.

The valve assembly 1 has a multi-part valve housing 26 which is screwed into the receiving bore 22 and tapers step-wise towards the pressure connection P. The three connections P, A and T are sealed off from one another by means of O-ring seals 28, which will not be discussed in more detail here.

The valve housing 26 essentially consists of an inner sleeve 30 and an outer sleeve 32 which engages around it in sections. The latter has an external thread with which it is screwed into the receiving bore 22. The protruding from the valve block 24 part of the outer sleeve 32 is expanded to a receiving portion 34 into which the electromagnet 20 is screwed. This has a conventional structure, so that only the part of the housing screwed into the receiving section 34 and a plunger 36 are shown in the illustration according to FIG. 2 - to an illustration of the other components, such as anchors, coil formers, pole tubes, etc. can be omitted with reference to the state of the art.

The inner sleeve 30 forms a valve bore 38, in which a valve spool 40 is guided axially.

The inner sleeve 30 has two axially spaced annular grooves 42, 44, the annular groove 42 forming an annular space 46 together with the inner circumferential wall of the receiving bore 22 in the region of the working connection A. The other annular groove 44, together with the inner circumferential wall of the outer sleeve 32, forms a further annular space 48.

These two annular spaces 46, 48 are over a first one

Radial bore star 50 or a second radial bore star 52 connected to the valve bore 38 of the inner sleeve 30. In the embodiment shown in FIG. 2, the first radial bore star 50 formed by two axially spaced bore stars with a comparatively small diameter.

The valve slide 40 has an end collar 54 and a rear collar 56, so that the central portion is radially recessed. Two control edges 58, 60 are formed on the annular collar 54 arranged on the left in FIG. 2. The connection between the front pressure connection P and the first radial bore star 50 can be opened or closed via the control edge 58 formed on the end face, while the connection between the first radial bore star 50 and the second radial bore star can be opened or closed via the other control edge 60 of the annular collar 54 52 can be opened or closed. This connection is made via the radially recessed area between the ring collars 54, 56.

The outer sleeve 32 is provided in the area of the annular space 48 with radial openings 62 so that the tank connection T is connected to the annular space 48.

The inner sleeve 32 is further provided with oblique bores 64, via which the tank connection T is connected to a spring chamber 66, which is delimited on the face side by the inner sleeve 30 on the one hand and by an end face of the valve slide 40 described in more detail below.

The valve spool 40 has an axial bore 68 which is narrowed to a throttle bore 70 in the central region. This throttle bore 70 opens into a radially enlarged guide bore 72 in which a pilot valve body 74 is guided axially displaceably. This has a cone, via which a valve seat 76 in the mouth area of the throttle bore 70 can be closed. In the basic position shown in Fig. 2, the pilot valve body 74 is biased via the pilot spring 18 in the open position in which the cone is lifted from the valve seat 76. On the end portion of the pilot valve body 74 remote from the valve seat 76, an axial projection 78 is formed, which bears against the end portion of the tappet 36. In the transition Area to the axial projection 78, a control edge 80 is formed, via which a connecting bore 93 to the spring chamber 66 can be opened.

The pilot valve body 74 has a through hole 98 through which the pilot spring 18 receiving space is connected to the rear of the valve spool.

A guide ring 82 is placed on the end section of the valve slide 40 protruding from the inner sleeve 30, by means of which the outer diameter of the valve slide 40 is enlarged relative to the end face on the pressure connection side. The outer circumference of the guide ring 82 is guided without play on the circumferential wall of an inner bore 84 of the outer sleeve 32, that is to say this inner bore 84 forms part of the valve bore 38 in which the valve slide 40 is axially displaceably mounted.

The guide ring 32 has an inner shoulder 86 which on the in

Fig. 2 abuts the right end face of the valve slide 40. The end face 88 protruding beyond the valve slide 40 is arranged at a distance from a stop 90, which, for example, on the housing of the

Solenoid valve is provided.

When no pressure is present in the pressure port P, the valve slide 40 is biased into its position (a) by the compression spring 16 accommodated in the spring chamber 66. This compression spring 16 is supported on the one hand on the adjacent end face of the inner sleeve 30 and on the other hand on the ring end face of the guide ring 32, so that the valve slide 40 rests with its stop shoulder 92 on the inner sleeve 30 and the end face 88 is spaced from the stop 90.

On the outer circumference of the valve slide 40, a stop shoulder 92 is also formed, which in the basic position (b) shown in FIG. 2 runs onto the end face of the inner sleeve 30 and thus defines an end position of the valve slide 40 while the another end position (a) is predetermined by running the end face 88 onto the stop 90.

In the overlap section between the guide ring 32 and the valve slide 40, an O-ring seal 94 is formed, which is fixed in a circumferential groove 96 of the valve slide 40 via a support ring. A certain amount of play is provided between the outer circumference of the valve slide 40 and the inner circumferential wall of the guide ring 82 encompassing it, so that manufacturing tolerances with regard to the coaxiality of the valve bore 38 in the inner sleeve 30 and the inner bore 84 in the outer sleeve 32 can be compensated. The seal 94 ensures that the gap between the guide ring 32 and the valve slide 40 is sealed, so that no short circuit between the spring chamber 66 and the rear of the valve slide 40 can occur.

Due to the inventive division of the valve slide guide into two sections with a small axial length, that is, the end section of the valve slide 40 with a smaller diameter guided in the valve bore 38 and the guide ring 82 guided in the larger inner bore 84, a significantly simplified production is possible, any manufacturing inaccuracies are compensated for via the O-ring seal 94.

In the basic position shown in FIG. 2, that is to say when the electromagnet 20 is not energized, the pilot valve body 74 is lifted off the valve seat 76. The pressure medium can thus pass from the pressure connection P via the axial bore 68, the throttle bore 70, the spring chamber of the pilot spring 18 and the connecting bore 98 to the rear of the valve spool 40, so that both end faces of the valve spool 40 are subjected to essentially the same pressure are. Since the right end face of the valve slide 40 in FIG. 2 is enlarged via the guide ring 82, a force acts on the valve slide 40 corresponding to this area difference, which acts on the valve slide 40 to the left against the force of the compression spring 16 (FIG. 2). The area ratios and the spring rate of the compression spring 16 are coordinated so that the valve slide 40 is brought into its illustrated basic position (b) when a predetermined pressure is reached. The connection from the pressure port P to the working port A is interrupted. The first radial bore star 50 is opened in this position by the control edge 16, so that the working connection A is connected to the tank connection T via the first radial bore star 50 and the second radial bore star 52, the annular space 48 and the radial openings 62. The spring chamber 66 is also relieved to the tank connection T via the oblique bores 64. This means that the pressure medium can flow back from the consumer to the tank T.

When the electromagnet is energized, the plunger 36 is moved to the left in the illustration according to FIG. 2, so that the pilot valve body 74 closes the valve seat 76. At the same time, the connection bore 93 is opened by the axial displacement of the pilot valve body 74 via its control edge 80, so that the rear of the valve slide 40 is connected to the tank connection T via the connection bore 93, the spring chamber 66 and the oblique bores 64 - which in Fig. 2 right end face of the valve spool 40 is relieved.

Since the pressure at the pressure connection P continues to act on the smaller end face, this is shifted to the right in the illustration according to FIG. 2 until the end face 88 hits the stop 90. This axial displacement of the valve slide 40 controls the connection between the tank connection T and the working connection A via the control edge 60, while the control edge 58 opens the connection to the pressure connection P to the working connection A, so that the consumer is supplied with pressure medium during the Tank connection T is blocked.

This switching position of the valve arrangement according to the invention is shown in Fig. 3. When the electromagnet 20 is switched off, the pilot valve body 74 lifts off the valve seat 76 again, so that the pressure on the pressure Final P acts and this is moved back into the switching position shown in FIGS. 1 and 2 due to the area difference against the force of the compression spring 16.

In the exemplary embodiment described above, in the flow-through basic position (b) of the 3/2-way valve 2, the working port A is connected to the tank port T, while the pressure port P is shut off.

The pressure spring 16 provides a position in which the ports P and A are connected to one another for the valve slide in the event that there is no pressure at port P. It is also conceivable to have a compression spring act on the valve slide 40 in the opposite direction instead of the arrangement shown. If there was no pressure in P, the valve slide 40 would then assume a position in which the connections A and T are connected to one another. The compression spring could be between the guide sleeve 82 and the electromagnet 20 in the space around the stack 36.

Of course, other valve constructions can also be realized with the configuration of the valve slide according to the invention.

In Fig. 4, an embodiment is shown in which the valve slide 40 is formed with jacket openings 100 which open in the region upstream of the valve seat 76 in the axial bore 68. In the basic position shown, that is to say when the electromagnet 20 is not energized, the axial bore 68 is connected to the second radial bore star 52 via the jacket openings 100.

In this exemplary embodiment, the two annular collars 54, 56 arranged at an axial distance from one another are not formed, so that there is no control edge 60. Accordingly, no connection from the working connection A to the tank connection T is provided. The diameter of the axial bore 68 is in some cases significantly larger than in the embodiment described above, so that the pressure medium without a significant loss of pressure from the pressure connection P can flow out to the tank connection T. The other components of the embodiment shown in FIG. 4 essentially correspond to the construction described in connection with FIG. 2, so that further explanations for the structure are unnecessary.

When the electromagnet 20 is deenergized, the pilot valve body 74 is lifted from its valve seat 76, so that the valve slide 40 is brought into its switching position shown in FIG. 4 due to the compressive forces acting on its end faces. In this, the connection from the pressure connection P to the working connection A via the control edge 58 is blocked, while the connection from the pressure connection P to the tank connection T via the axial bore 68, the jacket openings 100, the second radial bore star 52, the annular groove 44 and the radial openings 62 are opened is so that the pressure medium is returned to the tank T.

When the electromagnet 20 is energized, the pilot valve body 74 closes the axial bore 68, so that the larger end face of the valve slide 40 is relieved and this is moved to the right in the illustration according to FIG. 4. The control edge 58 controls the connection between the pressure connection P and the working connection A, while a control edge 102 controls the second radial bore star 52, so that the connection between the working connection A and the tank connection T is interrupted. In this switching position, the consumer is supplied with pressure medium.

The associated circuit diagram of this valve arrangement is shown in Fig. 4 bottom left.

Fig. 5 shows an embodiment in which, according to the switching symbol shown at the bottom left, the valve spool connects the pressure port P to the working port A in the basic position, while the connection between the working port A and the tank port T is open when the electromagnet is energized. For this purpose, the valve slide 40 is provided with jacket holes 104, via which the axial bore 68 is connected to the first radial bore star 50 in the basic position of the valve slide. The valve slide 40 is designed in a similar manner to the exemplary embodiment shown in FIG. 2 with two axially spaced ring collars 54, 56, so that a control edge 105 is formed by the radially recessed section in between, via which the connection from the working connection A to the tank connection T or more precisely to the second radial bore star 52 can be opened. The diameter of the axial bore 68 is large in the area between the pressure and tank connection to minimize the pressure losses.

When the electromagnet 20 (not shown in FIG. 5) is energized, the valve slide 40 is moved to the right by the pressure relief of the rear end face, so that the control edge 105 opens the connection between the first radial bore star 50 and the second radial bore star 52 and the working connection A with the Tank connection T is connected. About a through the jacket bore 104 formed control edge 106, the connection between the pressure port P and the first radial bore star 50 is controlled so that the pressure port P is shut off.

In principle, the construction according to the invention with the

Formation of an enlarged end face using a guide ring can also be used with other valve constructions with multiple formwork positions and connections. The use with proportional valves or with directly controlled valves is also conceivable.

In the exemplary embodiments described with reference to FIGS. 2 to 5, the larger end face of the valve slide 40 is delimited by a guide ring 82 which is placed on the rear end section of the valve slide.

In the case of shorter axial lengths of the valve slide 40 or in cases in which the manufacturing outlay is of minor importance, the enlarged end face of the valve slide 40 can be can also be formed by a radial collar 110 of the valve slide 40. That is, in this case the valve slide 40 is formed in one piece. This presupposes that the valve slide is turned almost along its entire axial length from the front end face (left in FIG. 6) to the radial collar 110. The compression spring 16 then engages the ring end face formed by the radial collar 110.

In the exemplary embodiment shown in FIG. 6, the radial bore 93 connecting the spring chamber 66 to the rear of the valve slide 40 is designed as an oblique bore, so that the opening area in the guide bore 72 is offset axially to the rear (to the right in FIG. 6) compared to the exemplary embodiments described above , Correspondingly, the pilot valve cone 74 is designed with the control edge 80 with a larger axial length. Otherwise, the exemplary embodiment shown in FIG. 6 corresponds to the variant shown in FIG. 4, so that further explanations are unnecessary.

Of course, the exemplary embodiments shown in FIGS. 2, 3 and 5 can also be carried out with a valve slide 40 which is provided with a radio collar 110 in the manner described above.

Disclosed is a pilot-operated directional valve in valve-spool construction, in which the valve spool is designed with a surface difference, so that when a pressure is applied to both end faces, it can be moved into a control position by a force resulting from the surface difference.

Claims

Expectations

1. slide valve with an axial bore (68) of a valve housing (26) guided valve slide (40), via which a working connection (A) with a return connection (T) or a pressure connection (P) can be connected, characterized by a Pilot valve arrangement (74, 76, 80, 93), via which the end faces of the valve slide (40), which are designed with an area difference, can be acted upon with a pressure or a pressure difference.

2. Slide valve according to claim 1, characterized by a guide ring (82) which is placed on an end portion of the valve slide (40) and is guided in the axial bore (68) and which forms the peripheral region of the larger end face of the valve slide (40) ,

3. Slide valve according to claim 2, characterized in that a seal (94) is arranged in a sealing gap between the guide ring (82) and the end portion of the valve slide (40).

4. Slide valve according to claim 3, characterized in that the seal (94) in an annular groove (96) of the valve slide (40) is inserted.

5. slide valve according to one of claims 2 to 4, characterized in that the guide ring (82) on the end face of the valve spool (40) is extended and that the inner bore is reset via a radial shoulder, which on the end face of the valve spool (40 ) is present.

6. Slide valve according to one of the preceding claims, characterized in that the end portion of the valve slide (40) with a larger end face in an outer sleeve (32) of the valve housing (26) and the portion of the valve slide bers (40) with a smaller diameter is guided in an inner sleeve (30).

7. slide valve according to one of the preceding claims, characterized in that a compression spring (16) on one of the larger

End face determining ring end face of the valve slide (40) engages and is supported on a housing shoulder.

8. slide valve according to one of the preceding claims, characterized in that the valve slide (40)

Axial throttle bore (68,70), via which the pressure at the axial pressure connection (P) can be guided to the larger end face and which opens into a pilot valve seat (76), which can be closed by a valve body (74) of the pilot valve, via which when the axial throttle bore (68, 70) is shut off, the pressure chamber adjacent to the larger end face of the valve slide (40) can be connected to the tank connection (T).

9. Slider valve according to claim 8, characterized in that on a remote from the pilot valve seat (76) shoulder of the

Pilot valve body (74) a control edge (80) is formed, via which at least one radial bore connecting the pressure chamber to the tank connection (T) (93) in the valve slide (40) can be opened.

10. Slider valve according to one of the preceding claims, characterized in that the slide valve is a 3/2-way valve, via which in the basic position (a) the working connection (A) with the tank connection (T) or with the pressure connection (P) or the pressure connection (P) is connected to the tank connection (T).

11. Slide valve according to claim 10, characterized by a compression spring (16) which acts on the valve slide (40) with a force acting counter to or in the direction of the pressure force resulting from the area difference.

2. Valve slide for a slide valve according to one of the preceding claims, the end faces of which are designed with a surface difference, characterized by a guide ring (82) which is placed on the valve slide (40) and limits the end face with a larger diameter.