JPH07502936A - Electrohydraulic control device and pressure reducing valve - Google Patents

Abstract

An electro-hydraulic control device (S) for a clamping device of an automatic lathe, with a pressure reducing valve (V) connected to a pressure source (1), the output of which can be connected via a directional control valve (W) to two user lines (11, 12) operable alternately, with a pressure switching device (D) fitted in the pressure reducing valve (V) and with a regulating input (20) to which control pressure can be applied, whereby in the directional control valve (W) there is a user pressure tapping (Z) at which the control pressure exists only in the control position (a and/or b) of the multi-way valve where the output (6) of the pressure reducing valve (V) is properly connected to a user line (11, 12), and in which the pressure tapping (Z) is connected to the control input (20). In the pressure reducing valve (V), between the control piston (14) and the pressure switching device (D) there is a mechanical, motion-transmitting link with which the pressure switching device (D) is actuatable directly by the control piston (14) once the monitoring pressure set via the force of the spring (22) has been reached.

Description

[Detailed description of the invention] Electrohydraulic control device and pressure reducing valve The present invention comprises an electrohydraulic control device according to the preamble of claim 1 as well as Relating to a directly controlled pressure reducing valve according to the preamble of scope item 8.

To ensure the fixation of workpieces in holding fixtures of machine tools, e.g. automatic lathes, The machine tool control system issues an acknowledgment signal or an acknowledgment signal when the required tightening pressure is achieved. If the clamping 11 pressure is lower than the required value, an error signal is sent to the machine tool. Tightening is pressure If the pressure is not reached, the acknowledgment signal will not appear. is automatically maintained via the pressure reducing valve regardless of the supply pressure. This tightening is the pressure value of the pressure is adjusted to meet each requirement at the pressure reducing valve.

Different processed products or different materials constituting these processed products are different from each other. Different tightening requires pressure.

Herion Belga (Germany) J, Luba Sofa City D-7012 W crke) KG Publication No. 7501614 dated May 2, 1986 For each equipment line leading to the retaining fitting, the tightening will be replaced by a new tightening when the pressure changes. A separate adjustable pressure switch that must be readjusted to the pressure V;A11I ＋Let's do it. This poses a safety risk. The reason is that the pressure switch This is because correct adjustments are sometimes ignored or performed incorrectly. the above The same publication states that the pressure switch should be integrated into the pressure reducing valve to eliminate this safety hazard. This section describes the means for converting the data. This pressure switch adjustment changed the pressure reducing valve adjustment A zero-problem pressure reducing valve, which can sometimes automatically adapt, is installed on a common shirt shirt for both equipment lines. Indirectly controlled reduction by supplying pilot pressure from each affected equipment line through a double valve. It is a pressure valve.

DE-C-3532592 discloses that the measuring piston is actuated by its own spring. A separate pot-shaped piston that acts as a pressure switch and operates the pressure switch independently of pressure. A direct control pressure reducing valve provided in addition to the control piston is described.

DE-C-3039002 discloses that in this case two separate throttle pistons are used. An electric current installed in addition to the control piston as a measuring piston that activates the pressure switch. A direct control pressure reducing valve in a body pressure control device is described.

The throttle piston is centered by two springs. The pilot pressure is Directed from the outlet of the pressure valve.

Electric current for machine tool parts as known from DE-C-3204055 In an indirect control pressure reducing valve installed in a body pressure control device, the pressure switch is connected to the pressure reducing valve's control piston. Operated by a ton pilot valve. control piston and pilot valve closing member; The pilot pressure for It is guided from the equipment conduit where it is acted upon.

Electric current for machine tool parts as known from DE-C-2310193 The pressure reducing valve installed in the body pressure control device is affected by the control spring and pilot pressure. The control piston is adjusted and measured in response to the pressure it is subjected to, independent of the force of the control spring. It can be placed inside the auxiliary piston that acts as a piston and operates the pressure switch. Ru. The pilot pressure for this control piston is in the direction placed on the downstream steel of the pressure reducing valve. Induced upstream of the control valve, but switching to the auxiliary piston and pressure switch Pressure is applied to equipment pressure lines, pilot lines and non-return checks with increased pre-tension. Induction through a valve. Two pyros equipped with check valves for safe functioning A common leakage line with a cut line and a discharge hole is required. These additional On the one hand, these components increase the construction cost, and on the other hand, these components do not have a safety function. is an additional potential source of error. This pressure reducing valve is complex and has many parts. consisting of goods.

An object of the present invention is to provide an electro-hydraulic control device as described above as well as other control devices. We have attempted to provide a direct control pressure reducing valve for use in such a control device at home. There is something to do. The electrohydraulic pressure control device and pressure reducing valve described above are structurally simple, but Furthermore, it is highly reliable with respect to the target safety function and consists of only a small number of individual parts. can reduce the number of potential sources of error. This pressure reducing valve also serves as a pressure switch means. Can be used universally in combination with other pressure monitoring devices .

According to the present invention, this object is achieved by the configuration stated in claim 1 as well as the concomitant claims. This can be achieved by the configuration described in claim 8 listed as the scope.

In the electrohydraulic control device according to claim 1, the pilot pressure is used for directional control. Directly inside the valve, it is easy to take out the device, and the directional control valve allows the equipment line to be routed to the desired location. Just connect it to the outlet of the pressure reducing valve like this. directional control valve is that correct Functions no longer need to be monitored separately and each separate pilot tube ducts, shuttle valves or check valves can likewise be dispensed with. this Control valves are simple and consist of a few parts.

If this directional control valve functions as intended, it will only actuate the pressure switch means. This pressure switch provides a reliable safety function when changing the adjustment of the pressure reducing valve. The switch means immediately responds to new demands with the pressure reducing valve! ! ! can do. direction The control valve becomes stuck in the operating process and cannot accurately occupy the monitored control position. This creates a pilot pressure for the pressure reducing valve and also for the pressure switch means to respond. . The pressure switch means either does not provide an acknowledgment signal or provides an error signal and 5. If the damage has been reported for a long time, or measures are taken to prevent damage. The pilot pressure is The directional control valve is displaced to such an extent that adequate supply is reliably guaranteed. up to the pressure take-off point, in which case the remaining displacement of the directional valve is still arise. Since pressure is the most important safety criterion when tightening holding fittings, The equipment for tensioning the pilot pressure for the reduction of the supply pressure only acting on the pipe line. It is better to induce, but to release the holding fixture, supply without pressure reduction. Pressure is used to control the direction of other equipment lines without inducing pilot pressure. It is connected to the outlet of the pressure reducing valve through a valve, in which case the pressure reducing valve is fully opened and no control action is performed. Make sure not to

The directional pressure reducing valve according to claim 8 is provided by a control piston via a tappet. Because it is directly actuated, it features a small number of individual parts, compact construction and high reliability. be a sign. When changing the adjustment of the pressure reducing valve control, use the pressure switch means separately. The response of the pressure switch means required for the safety function is piloted without the need for readjustment. Regardless of the method of displacing the control piston by pressure, is guaranteed regardless of the nature of the pilot pressure used by the pressure switch means. Reduced pressure for fluid pressure controllers when pilot pressure is available as the pressure to monitor. Pressure valves can be used universally.

Appropriate embodiments are described in the second claim. control piston and pressure Based on the motion transmission connection between the switch means, the pressure switch means The safety function remains reliable because it responds directly to movement or position.

The means according to claim 3 is provided in the intermediate and/or central position of the directional control valve. Therefore, no pilot pressure is generated and, conversely, there is no potential pressure drop. We guarantee that The simplest way to relieve pressure is to connect to a return line.

An embodiment according to claim 4 provides a low-cost construction with a control passage in the casing. Using a 4/2-way or 4/3-way slide valve, the mouth of the control passage should be located at the equipment pressure take-off point. form part of The basic concept of directional control valves is necessary to adapt to this pressure takeoff point. There is no need to change the It can be used for both equipment lines. In the former case, the equipment line is deactivated by the stopper. It can be done.

In the embodiment according to claim 5, it is a sliding piston.

Cutting to take out pressure at each control position or at one control position -5 A vertical passageway formed by the above is provided. Due to the structure and arrangement of this longitudinal passage, Pilot pressure is not induced in the intermediate position and does not open the directional control valve as expected. It is ensured that the pressure switch means will only generate a signal if the m organ No additional monitoring of the road is required.

In an embodiment according to claim 6, it is possible to directly Pressure relief can be guaranteed. Close the sump connection when the pressure take-off point is not in use.

A common common connector is used with the switching means to save time and form a short, low-loss flow path. It can be placed inside a compact casing.

The means according to claim 7 ensures that each channel always opens and closes in a predetermined manner. Important to ensure. The detent means is designed to prevent slipping if the supply of ttt flow is interrupted. to hold the piston in a controlled position and prevent the retaining fixture from releasing too quickly. . Two detection devices monitor whether the detent means locks as intended. It may be possible to output a signal indicating correct switching of the directional control valve. Ru. This means that the pilot pressure is not routed through the pressure take-off point, but at some point at the pressure reducing valve. 1 actuating magnet or sliding piston suitable for the embodiment in case of removal at other points Can be monitored alternately by backup device.

An embodiment of the pressure reducing valve according to claim 9 provides that the pressure switch is controlled by a control piston. It has the advantage of being directly actuated. Pressure reducing valves are compact and consist of only a few separate parts. Has a structure.

In an embodiment according to claim 10, the movement or position of the control piston is controlled by the tappet. Mechanically transmits the pressure to the tappet via the pressure switch. control without responding to surrounding pressure. According to each displacement of the control piston, the tappet is displaced by the control piston. pressure The switch can be arranged laterally, in which case the pressure reducing valve has compact construction dimensions. The pressure switch can be adjusted accurately.

In the embodiment according to claim 11, due to the progressive nature of the spring or spring structure: At the switching point of a pressure switch, for example when pressure is generated at the outlet of a pressure reducing valve Or the minimum permissible pressure chain is obtained when changing the feed rate.

In the embodiment according to claim 12, a structurally simple mode of transmitting the movement is obtained. It will be done. A common control piston is used since the connection is made by spring abutment. be able to.

In the embodiment according to claim 13, the Pilot pressure is directly induced by a pressure valve. Pressure reducing valves also allow pilot pressure to flow through equipment lines. It can be used for other modes of operation if it is not guided from the working path leading to the

The embodiment according to claim 14 connects each of the required passages and closes the other passages. This allows universal adaptation to various operating modes.

Embodiments of the subject matter of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of an electrohydraulic control device according to the present invention.

FIGS. 2 and 3 are I-I in FIG. 3 showing a pressure reducing valve according to the present invention, respectively. FIG. 3 is a cross-sectional view taken along line III--III of FIG. 2;

4, 5 and 6 each show a directional control valve according to the invention IV-IV FIG.

FIG. 7 is a sectional view of a modification of the pressure reducing valve of the present invention.

FIG. 8 is a sectional view of another modification of the pressure reducing valve of the present invention.

The electrohydraulic control device S according to FIG. By the transmission M used to perform the safety monitoring operation of the double-acting hydraulic cylinder of the holding fixture. A driven air-cooled constant displacement pump 1 sucks fluid medium from a reservoir 2 and creates a pressure reservoir. The storage means 4 is filled via the pressure line 3 via the pressure limiting valve. Pipe line leading to pressure reducing valve V 3a separates from the pressure pipe 3. The return pipe 5a is connected from the pressure reducing valve V to the return pipe 5. It also leads to reservoir 2. The pressure switch means is structurally connected to the pressure reducing valve. decrease The outlet side of the pressure valve V is connected to a directional control valve W, that is, a 4/2-way sliding valve, via a pipe 6. It is. A return line 5b leads from this control valve to the return line 5 (direction control valve W). connection parts P, T) and the outlet side of the directional control valve W are connected to the machine tool part via equipment pipes 11 and 12. The directional control valve W has an equipment pressure take-off point Z (connection parts A and B). (schematically shown in the markings of the directional control valve W). Take-out point Z is It is connected to a control input 20 of a pressure reducing valve V via a line 7. Directional control valve W is switched between two control positions a and b by two operating magnets 9 and 10. It has a sliding piston 8. Pressure take-off at intermediate position between two control positions The point Z is connected to the return line 5b, and the pilot line 7 becomes zero pressure.

The structure of the pressure reducing valve V is explained in detail in FIGS. 2 and 3 (first embodiment). Decompression The valve V casing a control piston 14 with two control edges 15 connecting the outlets. The outlet contained in the casing hole 13 is connected to the conduit 6, and the opening 18 of this outlet is connected to the conduit 6. The pressure connection 19 (return line 3 8) and the reservoir connecting portion 17 (connected to the return pipe 5a). to cross. Control piston 14 receives pilot pressure delivered at control inlet 20 The piston end 16 has a piston end 16 adapted to be acted upon by It is counteracted by the force of a spring 22 placed in a chamber 28 which is relieved of pressure.

The biasing force of the spring 22 is adjusted. The spring 22 connects the spring abutment body 23 via which it acts on the control piston 14. The head 2 of the tappet 26 is attached to the spring abutment 23. 7 is provided with a filler 24 that is positively engaged. The tappet 26 is the casing hole 1 3 and is adapted to be displaced within a hole 25 extending parallel to the 3. Tappet 26 transmits motion It is mechanically coupled to the control piston 14 via a spring abutment 23 at will. Tape The tappet 26 is aligned with the pressure tappet 28. Tappet 28 projects beyond hole 25 , actuating a pressure switch 29 sealed against the hole 25 and having a pressure switch notch means. It is intended to be used for

The two passages 30,32 are connected to the control inlet 20 via a connecting passage 33. General The passage 30 intersects the passage 33 following the opening 18, and the passage 32 crosses the passage 33 outside the pressure reducing valve V. 0 connected to a connecting part 7' provided on the side and connecting the pilot pipe 7. In the illustrated embodiment, the passageway 30 is closed by a plug between the opening 18 and the passageway 33 and is threaded. It is sealed from the outside by a stopper 31. However, the connecting part 7' is open and the pilot It is connected to the top pipe line 7. When the connecting part 7' is closed, the connecting part leading to the opening 18 is opened. The pilot pressure from the outlet 6 is then applied to the control inlet 20. There is also a connection part 7'. , a pipe which receives the higher pressure of the two instrument lines 11 and 12 via the shuttle valve. Connect the pilot pipes.

The spring 22 has a spring structure with progressive (non-linear) characteristics, so that the spring It is possible to provide several active springs or one spring with different winding sections. I can do it. The progressive spring characteristic is characterized by an increasing supply rate or rather an increasing working pressure. This has the advantage that the switching pressure of the pressure switch 29 approaches the operating pressure.

According to FIGS. 4, 5 and 6, the directional control valve is moved in the bore 34 for the sliding piston. It is provided with a sliding piston 8 which is movably guided and sealed against the bore 34.

The sliding screws 8 are arranged to be alternately moved by a tappet 37. Tape The shaft 37 is moved by actuating magnets 9 and 10. The detent means 36 is the sliding piston 3 Mechanically secure the two control positions of 5. Population 38 connected to outlet 6 of pressure reducing valve V is located at the center of the sliding piston hole 34. Groove shape formed by turning The outlets 39,40 are located on either side of the inlet 38. The reservoir connecting portion 43, T is It is provided on the side of each outlet 39,40 facing away from the inlet 38. return line 5b (FIG. 1) is a reservoir connecting portion 43, which is connected to T and has one cylindrical sealed section 42. The girder-sliding piston 8 is formed with flow pockets 41 diametrically opposed to each other. It is. Each pocket 41 is connected to the interior of the sliding piston 8 and controls each inlet 38. outlet 39 or outlet 40, the other outlet 40.39 connects to the adjacent reservoir. The sliding piston 8 is connected to the connecting part 43 via the narrowed part 35 of the sliding piston 8. sliding piste It is sufficient to provide one flow pocket 41 on one side of the tube 8. By pressure compensation Also, due to the smooth running of the sliding piston 8, flow pockets opposite each other along the diameter are formed. 41 is helpful.

Two diametrically opposed longitudinal passages 44 (shaped into sealed sections 42 by cutting) Did it happen? 11I) is formed in the circumferential direction. The longitudinal passage 44 is a flow pocket. 41, and are interconnected by diagonal through holes 48.

The control passage opening 45 of the sliding piston hole 34 is connected to one of the longitudinal passages 44 (the fifth (lower passage in the figure). The control passage port 45 is a part (part) of the control passage 51. The longitudinal passage 44 on the opposite side forms a transverse slot (connected to the pilot pipe 7). Intersect with 49. The slot 49 provides a reservoir connection in the reservoir passage 50 during movement of the sliding piston 8. The flow passes over the junction 46 and then between the longitudinal passage 44 and the return line 5b (FIG. 1). Generate connections. The pilot line 7 is released from pressure via said flow connection. Ru. The sump connection 46 is moved laterally with respect to the longitudinal passage 44 and only the transverse slot 49 so that it exceeds the reservoir connection part 46.

4 to 6 show the sliding piston 8 in its central position lb. , the outlet 40 is connected to the inlet 38 while the outlet 39 is connected to the sump connection 43. It will be done. The pressure in the equipment line 12 is applied to the central passageway port 45 as pilot pressure. , this pressure is sent to the control input line 20 of the pressure reducing valve (Fig. 1) via the pilot line 7. make it possible to do so. The connection to the reservoir connection 46 is provided by a transverse slot 49 (FIG. 5). It is not present because it is located to the right of the connection, and on the other hand the equipment line 1 The correct pressure between the two is thus transmitted as pilot pressure, and on the other hand It is ensured that the sliding piston 8 has virtually reached its correct control position.

For example, the sliding piston 8 does not engage against the detent means 36 and is stuck in an intermediate position. The control passageway port 45 is then connected to the reservoir via the transverse slot 49, and the pilot pressure I can't convey my power.

A particularly important aspect is that in all embodiments of the pressure reducing valve, the pressure reducing valve and the pressure switch hand Adjustment of the step is performed by a signal control member, that is, adjustment, against the biasing force of the spring or spring structure 22. It can be changed synchronously by screws.

The control piston of the pressure reducing valve ■, for example, the piston 14 in FIG. It is also conveniently used as a measuring piston. The reason is that it responds to the surrounding pressure. Is there no longer a member between the control piston and the pressure switch that can be displaced by It is et al.

In the embodiment according to FIG. 7, an axial tappet is provided on the control piston 14° of the pressure reducing valve V°. 54 is provided. A tappet 54 is attached to the control piston and connected to the control valve 20. located adjacent to and aligned with the pressure switch 29 to actuate the pressure switch 29; A tappet 54 extends through the sealing structure of the casing bore. this place The combined pilot pressure is conducted from the outlet 6 via the passage 30.33. close this passage 1, the control mass 20 is then connected to the pressure take-off point Z of FIG. 1 or directly to the system as shown. It is connected to two II vessel lines 11 and 12 via a shuttle valve.

In the embodiment of the pressure reducing valve V" according to FIG. 8, the tappet 26° is the same as in FIG. It is coupled to transmit motion to the control piston 14 via a spring abutment. Tape At 26°, there is a cam surface 5 that the cam follower arm of the pressure switch 29° abuts against. 6 is provided. This cam follower arm is located externally on the -left side of the pressure reducing valve V". This constitutes a part of the pressure switch means.

Instead of the 4/2-way sliding valve, a 473-way valve is used as the directional control valve W (as shown in Figure 1). It can be provided as follows. The device pressure take-off point Z is connected to the sump connecting part. or by communicating with an equipment line connected to the return line. released except for the new control position (a and/or b). When using a 4/3 way sliding valve The pilot line for pilot pressure is connected directly to the return line in a central position. However, both ejector lines are blocked or connected to a return line. Pilot pressure on one side If guided only at the control position, the pilot line will be connected to the return line at the other control position. It is connected to the equipment line that has just been opened, and this pilot line is released. each separately or a combination of these measures, if a good control system of the fixed fixture This serves to filter out incorrect acknowledgment signals of the pressure switch means responding at .

Claims (1)

[Claims] 1. downstream directional control connected to reservoir (2) for switching between each control position; Alternately connected to one of the two holding fixture equipment lines (11, 12) via valves (W) It has an outlet (18) cooperating with the control piston (14, 14') and has a pressure An adjustable pressure reducing valve (V, V', V'') connected to the power source (1) is provided to reduce the pressure. set by the valves (V, V', V'') and controlled as desired via the directional control valve (W). regulated to a monitoring pressure in at least one equipment line (11, 12) which is acted upon by a pressure switch regulated and operatively associated with said pressure reducing valve (V, V', V''); further comprising means D, further comprising an equipment line provided to and acted upon by said pressure reducing valve; Pilot pressure induced from the delivery pressure of the pressure reducing valve for (11, 12) The retaining fixture is equipped with a controlled inlet (20) adapted to add In electrohydraulic control devices (S) for holding fixtures of machine tools such as panels, the front The outlet (V, V', V'') of the pressure reducing valve (V, V', V'') is 6) is connected to the equipment pipe (11, 12) at the directional control valve control position (a and or b) ), only the pilot pressure can be induced, and this pilot pressure A device pressure take-off point (Z) used for inducing force is provided in the directional control valve (W). , the pressure take-off point (Z) is connected to the control inlet of the pressure reducing valve (V, V', V''). (20) An electrohydraulic control device (S) characterized in that it is connected to. 2. Said control piston (14, 14') imparts movement to said pressure switch means (D). 2. The control device of claim 1, wherein the control device is communicatively coupled. 3. The pressure take-off point (Z) in the directional control valve (W) is connected to the directional control valve (W). Between each control position (a and b) of the sliding piston (35), preferably the reservoir (2) a central position for closing or opening said equipment conduit (11, 12) by communication with between each control position (a and b) or between the central position and each control position (a and b). Claim 1 characterized in that the pressure is released at each intermediate position between (b) and (b). Control device as described. 4. The directional control valve (W) is operated by at least one actuating magnet (9, 10). so that it can be displaced in the sliding piston hole (34) between two control positions (a or b). and an inlet (38) connected to the outlet (6) of the pressure reducing valve (V) and the equipment line (1). 1, 12) and the outlet (39, 40) connected to the outlet (39, 40) is opened at each control position; The outlet (40, 39) connected to the other equipment pipe line (11, 12) is connected to the reservoir connection part (T ) 4/2-way or 4/3-way sliding valve with sliding piston (35) simultaneously connected to using the sliding piston (35) into the hole (34) for the sliding piston. connected to at least one outlet (39, 40) at each control position (a or b) and said A sliding piston (35) separates the two outlets (39, 40) between each control position. A device pressure take-off control passage port (45) is provided to separate the pressure from the pressure reducing valve (V) and the direction characterized in that the control valve (W) is preferably arranged in one common casing. The control device according to any one of claims 1 and 3. 5. At least one of said sliding pistons (35) is provided with a cylindrical sealing section (42). A flow pocket (41) partitioned in the axial direction and the circumferential direction is provided on the side of the control A passageway opening (45) is arranged outside the contour of said flow pocket (41) and said slip When viewed in the circumferential direction of the piston hole (34), the flow pocket (41) is A vertical passageway (44) partitioned in the axial direction so that the passageway opening (45) can move. is provided in the sealing section (42) of said sliding piston (35), and said longitudinal passage (44) ) is aligned with said control passageway opening (45) and at least one control position is aligned with said control passageway opening (45). It is characterized by connecting the road entrance (45) and the exits (39, 40). The control device according to claim 4. 6. A longitudinal passageway (44) is provided at each intermediate position and/or at said sliding piston (44). 35) at the center position between each control position (a, b) of the sliding piston (35). For sliding pistons through transverse slots (49) that intersect with longitudinal channels (44) A feature is that it can be connected to the reservoir connecting part (46) of the hole (34). 6. The control device according to claim 5. 7. The sliding piston (35) is secured against rotational movement within the hole (34). A detent means (36) is provided in the hole (34), and detent means (36) are provided in the defined two locations. and the detent means (36) correspond to each control position (a or b). ) acts on the sliding piston (35). 7. The control device according to any one of 6 to 6. 8. in response to pilot pressure and moving within the valve bore (13) against the force of the spring (22). pressure coupling by means of axially spaced control edges (15). Alternately controlling the communication of the outlet (18) with the connection part (19) and the reservoir connection part (17) A control piston (14, 14') is provided in the pressure reducing valve body to control the delivery. and signal-generating pressure switch means (D) for use in monitoring the pressure. Electrohydraulic control system for holding fixtures, especially for machine tools such as automatic lathes. In direct control pressure reducing valves (V, V', V'') for direct use, the control piston (1 4, 14') and pressure switch means (D), between which said control piston (1 This control piston (14, 14') can move together with the control piston (14, 14') mechanically transmits the motion of the spring (22) and reaches the set delivery pressure by the force of the spring (22). tappets (54, 26, 26') which actuate the pressure switch means (D) when ) A direct control pressure reducing valve (V, V', V'') characterized in that it is provided with: 9. The tappet (54) has a sealing effect on the control piston (14'). The pressure switch (29) can be moved along with the pressure switch (29). The pressure reducing valve according to claim 8, characterized in that: 10. The tappet (26 or 26') is arranged parallel to the control piston (14). mechanically coupling said tappet to said control piston (14); align with the pressure switch tappet (28) which can be moved in a sealed manner, or The cam surface (56) for the cam follower arm of the pressure switch (29') is attached to the tappet. 9. The pressure reducing valve according to claim 8, further comprising: ). 11. The control pistons (14, 14') are provided with a plurality of e.g. Spring or spring structure with progressive characteristics consisting of springs or helical springs with different windings According to any one of claims 8 to 10, characterized in that the effect is exerted by (22). Pressure reducing valve as described. 12. The spring abutment (23) is connected to the spring or spring structure (22) and the control piston. (14), and the tapepets (26, 26') are placed between the spring abutment bodies (23 and 23). ) according to any one of claims 8 to 11, characterized in that it is mechanically coupled to pressure reducing valve. 13. The pilot pressure for moving the control pistons (14, 14') is controlled by a pressure reducing valve. (V, V') from the outlet (6) or connected to this outlet (6) Any one of claims 8 to 12, characterized in that the method is derived from 12). Pressure reducing valve described in . 14. In the body of the pressure reducing valve (V, V'), there is a control valve connected to the control piston (14). Select the pilot pressure at the control inlet (20) through one of the two passages (32, 30). One of the passages (30) is connected to the pressure reducing valve (V). The outlet (6) leads to the control inlet (20), the other passage (32) leading to the casing. The control inlet (20) is connected to the control inlet (20) from the control inlet (20). The pressure reducing valve according to any one of claims 8 to 13.