EP1952032B1 - Hydraulic/pneumatic control valve with fail-safe function - Google Patents

Abstract

The invention relates to a hydraulic/pneumatic control valve, comprising a control slide (3) which is actuated by means of an actuating element (1) of an actuating device (2), which control valve is in force equilibrium with the pressure acting on the end faces of the slide (3), which control valve, in a first position, produces a connection via a relief duct (6) in the control slide (3) from a pressurized port point P to at least one port point A for a load, and which control valve, in a second position, breaks the connection of the port point A to the port point P and relieves the load A of pressure at a port point T into a tank via the relief duct (6), wherein the relief duct (6) is connected to the port point A and to the port point T, and is guided up to a port point (10), which is embodied as a control opening (8) in a retaining space (7) of the control valve, of the control slide (3) with the actuating element (1), and the connection of the relief duct (6) to the port point T can be controlled by the actuating device (2), a force-fitting and form-fitting connection in the form of a coaxial seal is provided between the control slide (3) and the actuating element of the control slide, and comprising a safety function, which, in the event of a malfunction of the control valve, relieves the load port point A of pressure to the port point T in the non-actuated state irrespective of the position of the control slide (3), wherein the port point A is relieved of pressure via the open seal (9) and the retaining space (7) to the tank (port point T). The invention is characterized in that the coaxial seal (9) is arranged at that side of the actuating element (1) which faces towards the port point (10).

Description

The invention relates to a hydraulic / pneumatic control valve according to the features of the preamble of claim 1.

State of the art

A generic control valve with fall-safe function is from the DE-A-103 08 910 known and finds use especially in tax tasks in the field of mobile hydraulics. The safety function is that in case of failure in any position in which the valve is moved by an actuator, a connected to the junction A hydraulic control element should be depressurized. This is realized in that a pressurized connection point P is connected to one or more further connection points T, which is connected to one or more containers, and thus relieves this connection.

In the aforementioned valve, the safety function is formed by a valve member into which a spool is integrated. The slide has for this purpose a coaxial bore, which is designed as a relief channel, which is connected via a transverse channel and control recesses in the form of an annular groove on the circumference of the spool with the consumer connection point. The end face of the spool formed by a plunger of an actuating element is open and opens into a control chamber. The transverse bore is designed so that it is connected to the connection point for the consumer both in the first position in which the spool is not actuated, and in a second position, and in any intermediate position between the two positions in which it was actuated is.

Even if no additional sealing measures are provided, the closed in normal operation compensation channel in the spool requires a metallic seal between the valve piston and actuator rod. But such a seal is only at an increased manufacturing accuracy of Slider possible. In addition, there are leakage problems with this type of seal, which greatly affect the life of the valve, which lead to a pressure drop at the consumer connection in normal operation.

In the generic arrangement no statement is made about the nature of a coaxial seal. In the arrangement, a valve function is integrated in the spool, which is in communication with a consumer port. Between the spool and the actuator of the spool, a positive and positive connection in the form of a coaxial seal is provided. The storage space is directly connected to an additional tank connection, through which the hydraulic medium can flow in the event of a malfunction. Normally, ie with the seal closed, the discharge takes place via another tank connection.

US 5,085,402A shows a solenoid valve, in the function of a poppet valve with the directly arranged in the axial direction inlet and outlet of the valve can be closed or opened by an axial lifting movement of a cylindrical actuator. The head of the actuating element is designed in the direction of the outlet channel as a sealing plunger which presses against the opening of the outlet channel when actuated, thus closes it in the form of a coaxial seal and releases the opening during the return and thus ensures a flow of the fluid. The known seat valve has no safety function. With the coaxial seal in the form of a sealing ram, the blocking and switching through in normal operation.

US Pat. No. 3,797,526 shows a pressure control valve with which a pressure drop is to be displayed in an inlet and outlet channel. The arrangement has an actuating device designed as a lifting magnet with an actuating rod arranged in the direction of action, which acts as a sealing tappet with a sealing head which normally seals the passage between an inlet and outlet channel. When pressure drops in the sealing head is pressed by the overpressure in the outlet channel against a retaining spring and thus opens the flow between inlet and outlet channel. The coaxial seal of the plunger works as a direct actuator for a pressure control valve. The known valve thus also operates as a seat valve.

EP 1 589 392 A1 shows a pressure control valve with a slide with control edges, which is arranged via a compression spring in a valve housing. The slide has an internal blind hole, through which, depending on the axial position of the slide, one pump and a plurality of working inputs can be connected or disconnected. At the end of the slide facing away from the spring, a fixed valve seat is arranged in the valve housing, which is held by a sealing element designed as a valve cone that can be acted upon by an actuating rod of an actuating element: From the valve plug, a discharge channel leads to a tank. By the spring of the slider is pressed against the fixed valve seat of the housing and built in the blind hole pressure, whereby a gap between the fixed valve seat and the valve cone is formed. As a result, the pressure medium can flow away via the drainage channel until the pressure is equalized. Upon actuation of the actuating rod, the gap is closed and the drain to the tank closed. By the occurring pressure imbalance, the slider is moved in the opposite direction to equilibrium. In the known pressure control valve, the pressure control via a cone seat connection, which is provided as an adjusting element for the pressure control. The coaxial sealing of the valve plug does not work directly against the spool but against a fixed valve seat in the housing.

EP 1 103 992 shows an electromagnetically actuated miniature pressure control valve with an electromagnet as actuator and an actuating rod which acts on a valve member having a valve spool which acts against the force of a return spring and each have a connection point A, a pressurized connection point P and a drain point T. Safety devices in the sense of a fail-safe function are not present in the valve.

The present invention has for its object to achieve an improved sealing in a generic control valve, which prevents leakage losses and a pressure drop, in particular during normal operation. The object is achieved in connection with the preamble by the characterizing part of claim 1.

The advantage of the invention is that no or only small leaks can occur at the point during a loading of a control slide by the actuating element by the positive and positive sealing at the head of the actuating element in normal operation, so that no pressure loss at the connection A occurs. In a malfunction, however, when the junction between the actuator and the control port is opened, a pressure built up at the junction A is guided through the discharge channel in the spool to the head of the slide in the storage space and degraded by the line connection between the storage space and the connection point T to the tank connection.

Additional lines in the spool valve, over which the safety function has hitherto been realized according to the prior art, are no longer necessary in the control valve according to the invention. To ensure the fail-safe function, the spool valve of a conventional valve only has to be slightly modified. For example, valve spools with the same outer contour can be used for the valve as for valves that work exclusively in "normal" function. The only requirement for use with valves in fail-safe function is that they have a continuous coaxial bore as a discharge channel.

In the normal function of the sealed head of the actuating element is located directly on the control port of the spool. The control opening of the slide is closed by the seal. The normal function can be described by two positions. In a position of the slide designated as the first position, the pressurized connection P is connected directly to the working connection via the discharge channel. The drain to the tank connection is blocked. However, the storage space is permanently connected to the connection point T via a line connection. Due to the further sealed connection point of the control opening of the spool there is no pressure drop at the consumer A.

In the second position of the spool, the pressure port P is locked. The consumer A is now connected via the compensation channel in the spool valve via the tank connection T connected to the duct. In this case, the sealing of the control port only has a sealing function which prevents excessive penetration of the fluid of the valve into the region of the actuating device. The connection of the connection P with the tank connection is blocked by the axial slide position.

In both the normal function characterizing positions of the spool thus the valve control function for the consumer is guaranteed.

In a malfunction of the valve, the control of the actuating element is terminated when, for example, the spool is blocked between the two position due to contamination or the like. The spool is placed in a position where the head ends of spool and actuator are spaced apart. In this position, which is located between the first and the second position of the spool described above, the port T is blocked from the consumer port A of the valve, however, the connection from A to the pressure port P is still open, so that the port A is still is pressurized. A relief of this pressurized connection point A is initially in conjunction with the designed as a coaxial bore in the spool discharge channel, the control port is now open and opens into a storage space. This space has according to the invention a conductive connection to the connection point of the tank T, so that in this way always a pressure relief of the consumer point A is ensured. The connection of the discharge channel via the storage space to the connection point T remains upright.

In the prior art line connections between the storage space and the environment in hydraulic / pneumatic control valves for driving a working device or a drive control are used exclusively for venting or emptying of the valve or the actuator of the fluid. A use of these cables for safety devices and fail-safe function is not apparent from the prior art.

The line connection is arranged within the outer envelope of the valve and runs parallel to the discharge channel of the spool. If further connection points to the environment are provided, then of course this connection can also be routed to these locations. It is only crucial that a pressure relief of the storage space is guaranteed at open connection between spool and actuator.

It has proved to be advantageous to carry out the sealing at the head of the actuating element with an elastomeric material. This material serves to better seal the control port. The seal can z. B. be realized by a mounted at the head end of the actuator plug or by a coating of the front page. The shape of the seal can advantageously be done either as an elastomeric piston or cone. In a first embodiment, the elastomeric material can occupy the entire radial surface. This is depending on the used material of the elastomer an elastic contact point provided that prevents or mitigates a hard impact of the actuating element on the spool at the connection point. By this measure wear and tear of the two components are prevented or significantly reduced.

For better fitting, it is advantageous if the elastomer seal is enclosed in a mouth-like, axial recess of the head part of the actuating element and terminates flush with the head part in the radial direction. The opening diameter of the mouth corresponds to the diameter of the control opening of the control slide, so that the seal is made by the embedded elastomer material. The power transmission from the actuator to the head of the spool takes place exclusively by the outer coaxial ring contact surface of the head of the actuator.

As a further elastomeric sealing a sealing over O-rings is advantageous, which are arranged in a circumferentially arranged groove on the end face of the actuating element. Structurally, the O-ring seal can be realized by a cylindrical pin arranged on the end face, on the outer circumference of which the O-rings are arranged.

If, in special cases of use of the valve, an elastomeric seal is not possible, the seal can also be designed as a flat surface of the front part of the actuating element. The actuator is executed in this case at the junction as a full piston surface which seals the coaxial opening bore of the spool.

Another advantageous possibility of sealing is that to perform actuator as a sealing plunger. The head of the actuating element is designed in this embodiment as a brass cone, the tip of which penetrates into the open end face of the spool and seals this point.

The sealing ram can also be constructed in a further advantageous embodiment in the form of a sleeve whose outer sleeve bottom forms the sealing surface with respect to the bore of the spool. Inside the sleeve, a ball or other shaped seat body is loosely arranged and is from the end face of the dipping into the sleeve opening head of the actuating element held in your position. The actuator abuts against the ball, which thus presses the outer sleeve bottom against the control hole. Such a construction prevents tilting of the joint, so that a complete seal is always possible.

To improve the pressure equalization between the end face of the spool and the actuating element, the spool in the stowage on a restoring device, which is suitably designed as a compression spring. The head of the spool in the storage space has radial shoulders for this purpose. One end of the compression spring is supported there while the other end presses against the bottom of the storage space facing away from the connection point. By this arrangement it is additionally ensured that the head of the actuating element in each switching position of the spool is always in contact with the control port of the slide and leakage in normal operation can be avoided by leaks.

A further advantageous embodiment of the invention comprises, in particular as an actuating device, an electromagnet whose armature with axially extended rod tappet forms the actuating element, at whose head the seal is arranged. For hydraulic control functions, a proportional solenoid is preferably used whose stroke / current characteristic corresponds to the axial displacement of the control spool.

For the safe operation both in the normal function and in the fail-safe function, it is also advantageous if the armature of the electromagnet is provided with an additional coaxial seal against its armature counterpart, at an axial distance to seal the connection point is arranged. By this measure it is prevented that the inflowing through the hollow spool hydraulic medium, especially at open junction of the spool with the armature plunger, can not flow into the armature space of the magnet, and flows exclusively through the discharge line from the storage space to the junction T.

Further details of the invention will become apparent from the dependent claims and the two embodiments described below.

embodiment

• Fig. 1 shows a longitudinal sectional view of a first embodiment of the inventive control valve in an overall view.
• Fig. 2 shows a longitudinal sectional view of a second embodiment of the inventive control valve in an overall view.
• Fig. 3a to Fig. 3c show in longitudinal section details of the Fig. 1 ,

At the in Fig. 1 illustrated hydraulic control valve is a working as a safety valve in fail-safe function 3/2-way proportional pressure reducing valve, ie the pressure to be controlled is applied to the end face of a spool 3 of a valve member 17 of the control valve and acts by an actuator 2 of a Actuator 1 generated force and the counterforce generated by a restoring device 5 against.

The valve member 17 , which is substantially the right side of the Fig. 1 comprises, consists of a sleeve-like valve body 12 and has, arranged at its left end face, a marked A connection point of a consumer, via a pressure line 4 , which is connected to a pressure port P , and with a working medium z. B hydraulic oil is supplied. The consumer may be either the direct hydraulic control of a drive or work system or the control of pilot valves for such systems. As a further connection point, the valve body 12 has on its periphery a third connection point for a tank T. The designed as a cylinder spool 3 has in its interior a coaxial discharge channel. 6 on, which extends axially over its entire length. The fail-safe function of the in Fig. 1 valve shown is that in case of malfunctions, the connection point A is to be relieved in any position of the control slide, A must be connected to T, at the same time the connection from A to P should be interrupted.

At the in Fig. 1 illustrated valve member 17 was a part of a cartridge-mounted cartridge in a designated location (Cavity). On the outer circumference of the valve body 12 are each three O-ring seals can be seen. Reference numeral 19 shows the O-ring seal between the actuator 2 and the atmospheric environment of the valve. In the axial direction between the terminals T and P and between P and A , the two other O-ring seals 20, 21 are arranged. These separate the supply lines of the individual connections in the cavity from each other.

In a the entire axial length of the valve body 12 extending coaxial bore 30 of the spool 3 is mounted. At the actuator 2 opposite end of the valve body 12 , the bore 30 opens directly into the consumer connection point A. The spool 3 has at its outer periphery in the axial region between the terminals P and T an axial recess 31 , and a recess connected to this radial connection 32 which is connected to the coaxial discharge channel 6 in the interior of the spool 3 . This discharge channel 6 extends over the entire axial length of the spool 3 from the junction A to a junction 10 at the other end.

The valve body 17 has, at its end associated with the actuating device 2 , a coaxial recess which forms a storage space 7 , in which the restoring device acts against the force effect of the confirmation element 2 . The restoring device is arranged as a compression spring about the outer diameter of the spool 3 and presses with its axially left end against the bottom of the recess and with the other end against a shoulder of the head of the spool 3 in this area. The discharge channel 6 of the spool 3 opens at this head end in a control opening. 8 The opening is firmly closed in the illustrated position of the slider 3 at the junction 10 with the head of the actuating element 1 .

The valve body 12 also has an axially disposed in the interior of the body line connection 34 through which a conductive connection of the storage space 7 is made to the tank port T. The connecting line 34 provides in the normal function for a venting or emptying of the fluid, which collects in the storage space or in the actuator 2 during operation. With the open position of the control opening 8 and the open connection point P, the line 34 fulfills the function that by this measure the connection A receives a direct connection to the connection T and is thus relieved. In the in Fig. 1 shown position of the spool 3 is in a functional failure of a consumer relief of the terminal A via the discharge channel 6 , the radial connection 32 and the axial recess 31 to the tank port T ensured. The connection P , ie the pressure supply, is blocked.

As actuator 2 shows Fig. 1 a cup-shaped electromagnet in construction as a proportional magnet. With appropriate design of a force-stroke characteristic of the magnet, a proportional relationship between the magnetic current and the pending on the spool 3 pressure is achieved. The magnet parts 28 of the electromagnet are surrounded by a pot-like housing pot 29 , at the bottom of the pot, a plug 22 is provided for the energization of a arranged in a bobbin 26 winding 25 . Embedded in the housing pot 29 , the yoke with a yoke disc 23rd The magnetic flux is closed via the winding 25 , via a non-magnetic material, designed as a hollow cylinder armature 14 and the characteristic influencing armature counterpart, which is designed in the region of the working stroke of the armature 14 as a cone 15 , which tapers against the stroke direction. The force generated by the magnetic field causes the armature 14 in the axial direction to the left stroke movement.

The armature 14 is guided via a bearing bush 24 in a sleeve 27 configured as a pot, which extends axially from the in the direction of the valve body 12 arranged end of the magnet member 28 , along the outer circumference of the cone 15 and armature 14 extends and there fixedly connected to both the bobbin 26 , and with the armature counterpart, and at its bottom of the pot the lifting direction opposite end face of the armature 14 comprises. Between the armature counterpart and the pressure sleeve 27 , an additional O-ring seal 18 is additionally provided as a seal of the magnetic member 28 against ambient media. In the direction of the lifting direction facing open end of the armature 14 designed as a plunger rod 13 is recessed, which forms the head of the actuating element 1 through a continuous coaxial opening of the armature counterpart at its other end. Within the opening of the armature counterpart of the plunger 13 is supported by a bearing book 16 .

By the lifting movement of the plunger 13 of the spool 3 is in a position to the left in Fig. 1 shifted, in which the connection P via the radial bore 32 and possibly via the axial recess with the discharge channel 6 of the spool 3 is connected. The junction 10 between the control port 8 and the head of the plunger 13 is closed by the application of the magnetic force. The working port A is supplied with pressure.

According to the invention, the head of the plunger 13 has on its front side a seal 9 , which the control opening 8 in the in Fig. 1 represented position of the spool 3 closes. In the execution after Fig. 1 the seal 9 comprises an elastomer material 11 , which is arranged in a coaxial recess of the end face of the plunger 13 . The elastomeric material 11 is pressed into the recess as a cone.

The execution according to the Fig. 2 differs only in the type of seal 9 of the execution in Fig. 1 , Therefore, the same reference numerals are used in the following for the same functions as in Fig. 1 , The material combination of plunger material (steel) and elastomer material 11 ( Fig.1 ) is executed in this embodiment as O-ring seal 33 . The directed in the direction of the control port 8 end face of the plunger head has for this purpose a radial pin, which is provided as a receptacle for the O-ring seal 33 . The sealing of the connection point 10 between the plunger and the control opening. 8 occurs outside circumference through the O-rings 33 , while the power is transmitted to the spool 3 by the steel of the plunger 13 .

The operation of the safety device for the control valve according to the invention is in the following to hand Fig. 3a to Fig. 3c explained. The Fig. 3a and Fig. 3b show the normal operation, both in a non-activated position of the actuator 2 - according to the embodiments of Fig. 1 and Fig. 2 corresponds to this position of a de-energized Etektromagnetenals and activated by the actuator 2 position of the spool 3 , that is, the solenoid is energized and the spool 3 is moved in the direction of the lifting movement of the plunger 13 axially to the left. In both positions, the control opening 8 of the spool 3 is closed, the head of the actuating element 1 is applied to the opening. The connection point 10 is positively and positively sealed.

In the position after Fig. 3a is the junction A for the consumer via the discharge channel 6 , the radial connection 32 and the axial recess 31 to the tank T relieved. The axial recess 31 of the spool 3 terminates at its right end in height of the tank port T and is connected thereto. However, the radial connection 32 is axially away from the pressure line 4 of the pressure port P , so that it is closed. About the radial connection 32 and the discharge channel 6 of the working port A is connected to the tank port T. The connection for a working device or for a pilot valve of a drive is thus shut down. The spool 3 is pressed by acting as restoring device 5 compression spring against the head of the actuating element 1 . The connection point 10 is closed. The line connection 34 parallel to the spool 3 within the valve body 12 exerts no safety function in this slide position, but serves exclusively for the usual venting or draining for the fluid of the control valve, which has collected within the actuator 2 (solenoid).

The position of the Fig. 3b shows the spool 3 in an activated by the actuator 1 position (energized state of the electromagnet to Fig. 1 or Fig. 2 ). The slider 3 is moved to the stroke of the actuator 1 so far axially to the left until the radial connection 32 is above the connection point P , but at the same time the tank outlet T is closed. The connection point 10 towards the actuating element 1 is still closed. The connection point A is connected in line with the pressure line 4 and the port P. Now can be built on the consumer pressure for the operation of a working device or a pilot valve for a connected drive system. Also in this position, arranged in the valve body 12 line connection 34 again serves only the venting and / or emptying of the storage space 7 or the actuator 2 (solenoid).

In the event of a malfunction, the actuation (energization) of the actuating device 2 is interrupted. The plunger 13 is moved axially to the left. Normally, the spool 3 would follow by the return spring 5 of the rear stroke movement of the actuating element 1 . If this subsequent movement of the slider 3 is disturbed, so he in the position of Fig. 3b , for example, by a chip, another object or generally stuck by dirt particles, is the working connection - like this Fig. 3c shows - still connected to the pressure port P. The pressurized medium accumulates in the storage space, but it can now flow through the conductive connection 34 of the storage space 7 to the tank outlet T. The working port A is thus relieved and the connected devices are shut down.

The invention was based on the example of a seal from an elastomer seal as a cone ( Fig. 1 ) or as O-ring seal 33 ( Fig. 2 ) explained. It also includes other forms of sealing, especially those in which the head of the plunger is made of the same material as that of the actuating element. This also includes sealing tappets with an associated seat body, which is confirmed directly or indirectly via an inner tappet. In addition to the described in the two embodiments hydraulic control valves, the invention also relates to pneumatically operated valves. In addition to the actuator as an electromagnet also belong manually or electronically actuated or triggered switching devices as actuators to the disclosure of the invention.

Claims (14)

1. A hydraulic/pneumatic control valve, comprising

   - a control slide (3) which is actuated by an actuating element (1) of an actuating device (2), said actuating element (1) being in force equilibrium with the pressure acting on the end faces of the slide (3),

   - in a first position produces a connection, via a relief duct (6) in the control slide (3), from a pressurized connecting point P to at least one connecting point A for a load,

   - in a second position interrupts the connection of the connecting point A to the connecting point P and, via the relief duct (6), relieves the load A of pressure at a connecting point T into a tank,

   - wherein the relief duct (6) is connected to the connecting point A and the connecting point T and is guided as far as a connection point (10) of the control slide (3) to the actuating element (1), said connection point (10) being configured as a control opening (8) in a retaining space (7) of the control valve, and the connection of the relief duct (6) to the connecting point T can be controlled by the actuating device (2),

   - a force- and form-fitting connection in the form of a coaxial seal is provided between the control slide (3) and the actuating element of the control slide,

   - and a safety function, which, in the event of a malfunction of the control valve, relieves the load connecting point A of pressure to the connecting point T in the non-actuated state, irrespective of the position of the control slide (3),

   - wherein the connecting point A is relieved of pressure via the opened seal (9) and the retaining space (7) to the tank (connecting point T),

   characterized in that the coaxial seal (9) is arranged at that side of the actuating element (1) that is directed toward the connection point (10), and provided between the retaining space (7) and the tank connection (T) is a conductive connection (34) which is arranged within an external sheathing (12) of the valve and parallel to the relief duct (6) of the control slide (3), wherein pressure compensating ducts which are present are used as conductive connection (34).
2. The control valve as claimed in claim 1, characterized in that the seal (9) comprises a plug made of an elastomeric material (11).
3. The control valve as claimed in claim 2, characterized in that the elastomeric plug (11) has a conical profile in the direction of the connection point (10).
4. The control valve as claimed in one or more of claims 1 to 3, characterized in that the seal (9) comprises a pairing made of the elastomeric material (11) and the material of the actuating element (1).
5. The control valve as claimed in claim 4, characterized in that the head of the actuating element (1 ) at the connection point (10) has circumferentially arranged grooves, in which an elastomeric seal, in particular an O-ring seal (33), is mounted.
6. The control valve as claimed in one or more of claims 1 to 4, characterized in that the head of the actuating element (1) at the connection point (10) has a coaxial recess in which the elastomeric material (11) is fitted.
7. The control valve as claimed in one or more of claims 1 to 6, characterized in that the seal (9) takes place by way of the elastomeric material (11) and the force is transmitted by way of that end face of the actuating element (1) that is arranged in the direction of the control slide (3).
8. The control valve as claimed in one or more of claims 1 to 7, characterized in that the actuating element (1) is configured as a sealing plunger in the direction of the connection point (10).
9. The control valve as claimed in claim 8, characterized in that the sealing plunger is configured as a sleeve, wherein the actuating element (1) moves into the coaxial opening in the sleeve and presses the latter by way of its outwardly directed bottom surface toward the opening bore in the control slide (3).
10. The control valve as claimed in claim 8 or 9, characterized in that the sealing plunger is configured as a cone, the tip of which presses against the connection point.
11. The control valve as claimed in one or more of claims 1 to 10, characterized in that the actuating device (2) comprises an electromagnet, in particular a proportional magnet, and the actuating element (1) comprises the plunger (13) of the armature (14) of the magnet.
12. The control valve as claimed in claim 11, characterized in that the armature (14) of the electromagnet is provided with an additional coaxial seal opposite its armature counterpart, said additional coaxial seal being arranged at an axial distance from the seal of the connection point (10).
13. The control valve as claimed in one or more of claims 1 to 12, characterized in that the switch from the first to the second position of the control slide (3) takes place by way of a restoring device (5) that is arranged in the retaining space (7) and acts on the head of the actuating element (1).
14. The control valve as claimed in one or more of claims 1 to 13, characterized in that the restoring device (5) comprises a compression spring, one end of which is supported on the shoulder of the control opening (8) in the control slide (3) and the opposite end of which is supported on the bottom of the retaining space (7).

Images