DE2302845A1 - PRESSURE COMPENSATION VALVE FOR HYDRAULIC PISTON VALVE - Google Patents

Description

Pressure compensation valve for hydraulic piston valves

The invention relates to a pressure compensation valve with a slide piston which is attached to a first Piston surface is acted upon by the inlet pressure in the direction of a bypass position in which the on Pressure medium entering an inlet port is bypassed to a food outlet port to an outlet port flows, and which is opposite to a second piston surface from a returned working pressure in Direction is applied to a feed position in which the pressure medium entering at the inlet connection to the Feed connection is supplied.

Such valves are mainly used as bypass pressure compensation valves for piston valve assemblies which, in the neutral position, control the flow between the inlet and block the outlet. The hydraulically movable piston of the compensation valve, the one with the piston slide of the control spool works together, varies the

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Pump flow «£ ls?, & To the inlet of the control slide accordingly the pressure difference between pump outlet pressure and motor connection pressure of the control spool.

If the spool of a control spool that blocks the flow in the neutral position is in a neutral or holding position in which the motor connections are separated from both the inlet and return channels, the pump outlet pressure can no longer be reduced via the control spool such time acts on the light coming from the pump pressure means that a piston end of the associated pressure compensating valve against a restoring spring which engages at the other end of this piston, so that it is held in a shunt position, are in which all coming from the pump pressure medium diverted to an outlet can*

If, however, the spool of the control slide is in a working position in which the pressure medium is fed to one of the motor connections, the fluid pressure that is established at the motor connection is fed back to the pressure compensation valve so that it can then attack the other end of the compensation piston in order to work together with the power of the Rüokstell-

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spring the compensation piston in a feed position in which the pressure drop between the pump outlet and the motor connection is kept at a constant value will. This value depends on the size of the opening on the control spool piston that restricts the flow, Via which the pressure medium reaches the selected motor connection. In this way, it will be shunted flowing pressure medium is reduced by the amount that is in. Via the control opening of the control spool piston a certain working position can flow to the motor connection.

In general, the piston of the pressure compensation valve is provided with a strong spring which acts against the feed position. It is known to a person skilled in the art that precise adjustment of the operating speed of the controlled hydraulic motor is only possible if. the spring force is large enough to ensure the desired rapid response of the pressure compensation piston to the slightest changes in the pump outlet pressure and / or the returned motor connection pressure under all working conditions

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Λ . *

The importance of a pressure compensation piston that is preloaded with spring force against the feed position is well known. However, a very serious problem arises from this measure, which has not yet found a usable solution. As already mentioned, the compensation piston must be held in a bypass position when the control valve piston is in the neutral or Holding position. The purpose of this measure is to relieve the pump in the same way as with one Control slide, which in the neutral position with its slide piston a free flow allows between inlet and outlet.

Up to now, however, it was only possible to partially switch the pump to the neutral position of the control slide. to relieve, because at this point in time the pump must deliver an output pressure that the compensation piston holds against the force of the strong return spring in the bypass position. Not only is a significant amount of energy wasted, but one also results

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unwanted heating of the pressure medium as an unavoidable consequence of such an unproductive How the pump works.

Based on the above problem, the object of the invention is to create a compensation valve whose between a feed and a shunted position of movable pistons in the shunted position with an extraordinary low pump outlet pressure can be maintained while in the feed position of the Valve piston a desired strong spring force is effective, a return movement to the shunt position counteracts

According to the invention, this object is achieved in that the slide piston is supported by a primary spring in The direction of the feed position is applied and a secondary spring is provided, which is in the shunt position of the slide piston is switched on with an auxiliary piston arrangement in such a way that their spring force corresponds to the spring force of the primary spring

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counteracts and the spool in the bypass position with significantly reduced Spring force is supported.

Preferably, the primary and secondary springs are connected in series to under the influence of the Inlet pressure to oppose a movement in the direction of the bypass position only a small force, the force of the motor connection z returned pressure medium is used to the secondary spring ineffective make so that the full force of the primary spring and the pressure medium returned from the motor connection are available on the compensation piston to prevent a return movement of the valve piston to counteract from the eating position.

The invention is directed not only to pressure compensation valves, but also to bypass valves per se.

According to a preferred embodiment of the invention, the auxiliary piston is located between the primary and secondary springs and is actuated by the returned working pressure in a direction in which the Secondary spring relaxed

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Further details and features of the invention result from the following detailed description and the "accompanying drawings, in which preferred embodiments of the invention are illustrated by way of example

In the drawings show:

3? Ig. 1 a schematic representation of a

hydraulic piston valve with a pressure compensation valve according to the invention in shunted position,

]? ig "2 an axial section through the pressure compensation valve the Pigo 1 in the feeding position,

Pigo 3 is a schematic sectional view one designed according to the invention Pump relief valve and

Fig. 4

and FIG. 5 schematic sectional views of a

pressure compensation valve according to the invention in a modified version o

In the reversible hydraulic shown in lig »1 Motor 5 is a reversible one

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Hydraulic cylinder, the piston rod 6 of which can be connected to a load, not shown. The working cylinder receives the pressure medium from a pump P according to the setting of a control slide. The control valve shown as an example is a piston slide 8 with a single slide piston in a conventional design. The slide piston 9 is axially displaceable in working positions on both sides of the neutral position in relation to the shown Heutralstelkung in order to supply the pressure medium coming from the pump via an inlet channel 10 to one or the other motor connections 11,12 connected to the opposite ends of the working cylinder.

The control slide is "an in the IT neutral position shut-off valve with a feed jc & iialirsii located in front in the direction of flow -14 » which can be referred to as the inlet of the piston valve, and a rear one in the direction of flow % ice channel part 15 »that via the bore 16 of the spool valve housing with the front feed channel part 14 can be connected »The rear feed channel part 15 is connected via a load-holding non-return valve 17 the inlet port 10 in connection »

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The inlet channel 10 is TJ-shaped and intersects with its "two arms 18 and 19 the bore 16 at points opposite to the motor connection channels 11 and 12 are offset inward. The slide piston is provided with circumferential grooves so that piston sections arise, which the connection between the motor connections 11,12 and the inlet duct arms 18,19 or with the reflux channels 20,21 «, the reflux channels 2Oy 21 cut the bore 16 at points which with respect to the junctions of the motor connection channels 11 and 12 are axially offset outward.

A central piston section 22 of the slide piston is arranged so that in the neutral or holding position shown, the slide piston opens the connection between the feed channel parts 15,16 which the pressure medium flows from the front feed channel part 14 to the rear feed channel part 15 when the slide piston is moved in any direction in a metering position from the neutral position until the full working stroke of the slide piston is reached, _etc.

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In a dispensing position of the shifted to the right The pressure medium entering at the feed channel part 14 flows through the valve piston 9 via the throttle notch 23 to the end of the working cylinder 5 on the rod side the rear feed channel part 15, the check valve 17 and then with the motor connection channel 11 in Connecting arm 18 of the inlet channel 10. In the metering position of the slide piston, which is shifted to the left reaches the pressure medium entering the front feed channel part 14 via the throttle notch 24 to head-side end of the working cylinder 5 via the rear feed channel part 15, the check valve 17 and then with the motor connection duct 12 in connection standing inlet duct arm 19 * In both cases the motor connection duct which is not selected is also shown the adjacent return channel 20 or 21 in connection, in order to supply the pressure medium released by the working cylinder 5 to the collecting container of the system

The pressure compensating valve 25 according to the invention is located in the system between the pump Έ and the spool 8. The valve 25 has the task of keeping the DruckmittelzufluS to the cylinder constant at a value of ₉ by the administering position, d ₀ h _0, the comparison

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As is generally the case, the pressure compensation valve is connected to a hydraulically displaceable valve piston, which responds to the pressure drop at the throttle notches 23 or 24 in order to control the pressure drop from the pump to the front feed channel part 14 according to the fluctuations in the pressure drop rules, which result from the value that should be present when the pressure medium is fed to the hydraulic motor at the desired speed

The valve piston 26 of the pressure compensation valve contains recesses at its opposite ends. The valve piston 26 is axially displaceable in a bore 27 closed at both ports, into which five different connections open out at axially spaced points. These connections are from left to right by a depressed <3 he return flow connection 28, a return connection 29, an outlet connection 30, an inlet connection 31 and a feed connection 32 _o

The reflux connection 28 can be part of the reflux channel

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The feed connection 32 is connected to the front feed channel part 14 via a line 33. The return port 29 can, in a conventional manner Connected via a switching valve either to the motor connection or 12 wasens in the illustrated slide arrangement with only one slide piston, the return connection 29 is connected to the arm 18 of the inlet channel 10 connected via a line 34 "

The Rtiekführansebluß 29 can also be connected to the rear feed channel part 15 with the same result The return port 29 is vented to the system sump when the spool is closed is in the neutral position and then with an Asrialbohrung 35 of the slide piston via its radial Arms 36, 37 establish a connection between the inlet channel arm 18 and the return channel 20 is.

Locked in the neutral position of the spool 9, like Pig. 1 shows the piston portion 22 the connection

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between the front and rear feed channel parts 14 and 15o The Iförderfluß from the pump then passes into the inlet connection 31 of the compensation valve and "acts on the right end of the valve piston 26 such that the valve piston remains in the Ifebensehlußstellung if the entire Eörderfluß of the pump through the Circumferential groove 26 * of the valve piston, which bridges the connections 30 and 31, flows to the outlet connection 30 »Here the pressure chamber 38 at the right end of the bore 27 is connected to the inlet connection 31 via a radial bore 39 on the hollow end part of the valve piston * The radial bore 39 has a constant connection to the feed port 32 and thus also to the inlet port 31 laßkanal 10 has then substantially the same size as the pressure of the then connected motor terminals 11 and 12o In the usual manner, this pressure is returned to the compensation valve ₉ in order to expose the left end of the valve piston 26 against the force

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the pressure medium coming from the pump exerts in the pressure chamber 38 at the right end of the valve piston _o The valve piston 26 is also biased in the usual way with spring force in the direction of the feed position

According to the present invention, the biasing force for the valve piston 26 is supplied by two compression springs, namely a fairly strong primary spring 40 and a weaker secondary or auxiliary spring 41 β these two Springs 40 and 41 are on the left end of the valve piston

26 attached to opposite ends of a stepped piston 42 «, the primary spring 40 lies in the recess 43 in the hollow left end of the valve piston between the bottom of this recess and the adjacent inner one

End portion 44 of the piston 42 _s which has a smaller diameter than the recess 43 hate Preferably, between the piston 42 and the primary spring is a washer 45ο The piston 42 is extending in a graduated cylinder 46 ₉ which koaxial.zur bore 27 slidable The smaller diameter formed inner end portion of the cylinder 46 sinks into the bore

27 a "

One end part of the secondary spring 41 protrudes into an extension

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recess 47 in the larger diameter formed outer end part 48 of the piston 42 »Das the other end of the triple edge 41 protrudes into a recess 49 a closure cap 50 into it, which is the larger diameter formed outer end portion of the cylinder

46 closes _β In this embodiment, the secondary spring 41 lies between the bottom surfaces of the recesses

47 and 49ο

The larger-diameter end part of the cylinder 46 is longer than the piston part 4S ₉ which can be moved therein. The shoulder in the cylinder forms a stop 51 and the inside of the cap 50 forms a second stop 52 "These stops 51 and 52 limit the axial movement of the piston part 48»

The stepped piston 42 has a TJmfangsrinne in its center 53 between its two piston parts "This region of the TTmfangsrinne 53 is the 55 'that receives via a radial bore 54 in the wall ISylinderteiles the flask vented. The inner end of the “ cylinder part” also forms a stop which defines the neutral or full lift-closed position of the compensation valve piston 26

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The stepped piston 42 is provided with an ibcial bore 57, via which pressure equalization between the spring chucks at the opposite ends of the stepped piston 42 can take place ₀

In the neutral or holding position of the control slide piston _{9f shown} in FIG. 1, the compensation valve piston 26 is in a bypass connection in which the entire pressure medium coming from the pump can flow from the inlet connection 31 to the outlet connection 30 in the bypass to the supply connection 32. This state arises from the fact that the primary and secondary spring chambers 43 and 47 are ventilated via a bore 58 in the side wall of the chamber 43 and the return connection 29 to the return flow channel 20. In this connection it should be remembered that the return connection 29 is in the Neutral position of the control slide piston via the line 34 »the inlet channel arm 18 and the bores 35, 36 and 37 of the control slide piston 9 are connected to the return flow channel 20,

When the spring chambers are ventilated in this way, can be the pump outlet pressure at the inlet port 31, which

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the right end of the compensation piston 26 in the chamber 38 "is applied, the latter slightly against hold the force of the primary and secondary springs 40 and 41 in the bypass position. In this Case, the primary and secondary springs work against each other. The total force they exert on the spool, which endeavors to push the spool out of the lift-closed position is much less than the force that the primary spring 40 alone could exert. Since the two springs 40 and practically connected in series, can be the exercised from within Calculate the total force in the same way as the total resistance of electrical resistors connected in parallel, if one considers the forces of springs 40 and 41 with R1 and R2, the total spring force results

■ nm R1 3C R2

R ₁ «Er— ^

Assuming as an example that R1 = 7 kg / cm and R2 = 3.5 kg / cm ² , the total force RT is 2.3 kg / cm * Outlet port 30 kept at a very desirable low value when the control spool piston is in the neutral position and then also the Kompensaticms-

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valve piston spool 26 a corresponding ISeutral- or lift-closed position, as shown in Figo 1 shows"

The spring force acting on the compensation spool but - which is very important - is considerably larger if the control piston 9 is in a working position Moved position in which the pressure medium at high pressure from the inlet channel 10 to the selected motor connection 11 or 12 flows »Assuming that the control spool piston is moved to the left, the pressure medium coming from the pump flows from the front feed channel part 14 via the throttle notch 24 »the rear feed channel part 15, the check valve 17 and the arm 19 of the inlet duct to the motor connection 12.

The fluid pressure that is established in the cylinder head is transmitted via the inlet 10, the line 34, the return connection 29, the bore 53 of the compensation valve slide piston 26 and the axial bore 57 of the piston to the spring chambers 43 and 47 transferred

The returned pressure medium in the chamber 47 pushes the piston 42 into the limit position shown in FIG.

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so that there is a discharge of the secondary spring 41st 33a now the secondary spring 41 has become ineffective, the full force of the primary spring 40 comes into effect without any counteraction of the secondary spring 41 on the valve piston 26 of the piston 26 and the pressure medium guided back by the cooperating forces 3 and the primary spring 40, which come into action at the left end of the piston 26.

With each predetermined setting of the control slide piston 9, the compensation valve slide piston 26 adjusts itself automatically in order to change the fluid pressure at the feed connection 32 as a function of the fluctuations in the pump outlet pressure at the inlet connection 31 ssu. In other words, this means that the adjustment of the valve piston 26 takes place as a function of the fluctuations in the pressure guided by the pressure. The piston 26 moves due to such pressure changes in such a direction that the changed operating conditions are compensated and the pressure at the supply connection 32 remains at a constant value, for example

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the basket 26 "moves" to the right to increase the fluid pressure at the feed port 32 when on Hückfübransehluß 29 a pressure increase is detected » In a corresponding manner, the piston 26 is moved to the left to reduce the feed connection pressure, when the pressure at the return connection 29 drops.

It can thus be seen that, in the illustrated single-piston valve arrangement, the compensation valve piston keeps the pressure at the feed connection 32 constant by changing the passage connection between the inlet connection 31 and the outlet connection 30 to keep the feed connection pressure constant by changing the passage cross-section between the feed connection 32 and the inlet connection 31 if the outlet connection 30 is used as a pressure transmission connection for a downstream control slide, the slide piston of which must operate a hydraulic motor with a higher pressure than this is the EaIl for the control slide located in front of it in the direction of flow _{or the like}

An actuation of the spool valve 9 in a

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The full working position naturally means that the outlet connection 30 is separated from the inlet connection 31 is so that all of the pressure medium coming from the pump flow to the associated working cylinder can.

However, as soon as the control slide 9 is returned to the neutral position, a shut-off occurs of the front feed channel part 14 and for ventilation of the return connection 29 ″. Through that now to the chamber at the right end of the piston 26 flowing pressure medium coming from the pump, the piston 26 is in the bypass position adjusted, in which, in turn, the secondary spring 4-1 can become effective in order to counteract the primary spring 40 β

From the above explanation of the mode of operation it can be seen that the spring force with which the compensation _{piston 26 is pressed out of the bypass position is desirably small, while a much greater spring force is available 9 to} move the piston 26 out of its feed position when the pressure medium is fed to one or the other end of the working cylinder 5 »Through this last-

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the effect mentioned is the desired precise speed control for the working cylinder 5 made possible

3 ze igt j as Peder He & hense entertainment with advantage in a pump relief valve can be applied _e In many respects, the relief valve the pressure compensation valve described above is similar "even though it may be a simpler design something. Here the slide piston 65 is cup-shaped corresponding to the left, larger diameter end part of the pressure compensation piston 26. The closed bottom part 66 of the slide piston works together with a valve seat 67, which is formed by a short part of the bore 68, from which the slide piston 65 is received axially displaceable. Seen from left to right, the relief valve contains a collecting tank connection 69, a return connection 70, an outlet connection 71, an inlet connection 72 and a feed connection 73. While the inlet and outlet connections open into the bore 68 on axially opposite sides of the bore part 67, The feed connection 73 can be connected directly to the inlet connection 72 or form a part thereof, as FIG. 3 shows.

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The collecting container connection 69 opens into a counterbore 74 * in which a stepped cylinder ■ forming insert 75 is attached, which receives the stepped piston 76 as before in an axially displaceable manner »The primary and secondary seders 77 and 78 are located on opposite sides Ends of the piston 76, the primary Seeder 77 into the hollow interior 79 of the slide piston 65 intervenes

The valve piston 65 protrudes out of the bore 68 into the Gregen bore 74 to the inner end of the To act on insert 75 and thus as a stop to serve for the piston 65 in the fully open or lift-off position, on the & i8enraantel des Piston 65 is located in a circumferential groove, a snap ring 80, which is located on the step surface 81 between the bores 68 and 74 can come to rest to the shut-off position of the piston 65, in which the right end of the piston 65 lies in the bore part 67 forming the valve seat, in order to establish a connection between the inlet connection 72 and the outlet connection 71 to block ",

As before, a bore 83 in the side wall of the piston 65 serves to establish a connection between the return valve

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connection 7ö and the interior of the piston 65 so that a pressure supply to the chambers at the opposite ends of the stepped piston 76 can take place in this way _e

The pump relief valve works essentially in the same way as the pressure compensation valve. When the associated control slide cage is in the neutral position, the return port 70 is ventilated and the feed port 73 is shut off. As a result, the pressure medium coming from the pump, which is fed to the inlet port 72, acts against the floor 66 of the slide piston 65 _{9 in} order to move it into the illustrated fully open position The pressure medium supplied then flows to the outlet connection 71 and from defct. back to the collecting tank! with only a slight pressure drop between connections 71 and 72 «,

But as soon as the control slide piston of the associated control piston slide is moved into a working position is, so that the pressure medium coming from the pump over

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the supply channel can flow to a selected motor connection, the pressure is transferred from the motor connection channel to the return connection 70 of the relief valve to "pressurize both Eederkammern at the opposite ends of the stepped piston 76" * The pressure medium in the secondary spring chamber then moves the stepped piston 76 in the direction of Slide piston 65 "whereby the secondary spring 78 is relieved" The pressure medium in the primary fire chamber acts directly on the piston 65 in order to move it in the direction of the closed position. The Sebieberkolben 65 can occur through the interaction of the acting on it forces in the bore portion 67 to the outlet port 71 shut off from the inlet port 72 ₉ so that the light coming from the pump pressure medium can flow from the inlet port 72 undiminished to the feed terminal 73 and to be controlled working cylinder _e

The Sehieberkorben 65 may also pass into an intermediate position, in which a ¹ IEU the light coming from the pump pressure medium flows to the outlet port 71 and the rest to feed terminal 73 »Such a position results from the fact ,, that the slide piston of the control spool valve is moved into a dosing position ,

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as it was already described earlier «Now he can Piston 65 respond to changes in the pressure drop that result at the throttle notches over which the working cylinder is supplied by the pump.

It is also obvious to the person skilled in the art that the return connection 70 of the relief valve can be connected to the motor connections of the associated control slide in a more or less conventional manner via a switchover valve _{or the like}

3? Ig _o 4 shows a further embodiment of the pressure compensation valve according to the invention ο The valve spool 89, the 1st shown in Fig. 4 in the Nebensehlußstellung, has a TJmfangsrinne 90th The piston 89 is displaceable in the longitudinal direction in a bore 91, the opposite ends of which are closed _e

In the illustrated pump relief position, the circumferential channel 90 of the piston 89 connects the inlet connection 93 with an outlet connection 94 'so that the pressure medium coming from the pump is shunted to a feed connection 95 flows »The piston 89 assumes this relief or bypass position when the slide piston

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of the associated control spool in the neutral position and prevents drainage from the feed connection is. At this point in time, the left end of the bore 91 is ventilated via a return connection 96.

Limited in the feeding position shown in Fig. 5 or the left portion of the piston 89 blocks the flow from the pump to the outlet port an adjustable amount of pressure medium via the t & nfangschinne 90 to the feed connection 95 "The piston 89 comes into the feed position by actuating the slide piston of the associated control slide into a working position, in which the pressure medium coming from the pump is passed on from the feed connection to the hot water connection and the bypass port 96 is pressurized in the manner previously described.

Coaxial recesses 97 and 98 at the opposite ends of the piston 89 form the spring-receiving pressure chambers _e A secondary spring 100 in the recess acts on a piston 101, which is

scülagstteilung can run up against the adjacent end of the bore 91 _o In this stop or limit position, the piston 101 holds the secondary spring 1oo weakly.

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cocked The piston 101 can under the fluid pressure are pressed into the chamber 1o2 at the right end of the bore 91 into the interior of the recess 98, to compress the secondary spring 100 nooh further " For this reason, the recess 98 is continuously connected to one another via a bore 104 in the compensation piston 89 Collecting container connection 103 ventilated.

The secondary spring 100 strives to move the compensation piston 89 to the left in the direction of bypass or pumps to move relief point »The secondary spring 100 counteracts the primary spring 105, which is located in the Recess 97 is located at the outer end of the compensation piston 89 and strives to move the piston 89 into the feed position to move ο The secondary spring thus works against the primary spring, which is, however, slightly stronger and usually strives to the To move the compensation piston 89 in the bore 91 to the right into the feed position.

The pressure chamber 102 is at the right end of the bore 91 constantly with the feed connection 95 and thus also with the inlet connection 93 via a bore 106 of the compensation piston 89 in connection.

- 29 - 23028A5

The piston 101 is provided with a pin 107 which coaxially protrudes into the secondary spring 100 and is directed towards the bottom of the recess 98, where it acts as a stop dieit, in order to limit the inward movement of the piston 101 relative to the compensation piston »

In operation, the compensation piston 89 is normally held in the bypass or pump relief position _? as long as the piston of the associated control slide: .n the neutral position to vent to the return port 96 and _o shut off the light coming from the pump pressure medium of the feeding terminal 95 Under these circumstances, the light coming from the pump pressure flows directly to the outlet port 94 in shunt with the Speiseanachlußi The corresponding pressure is also established in the chamber 102 at the right-hand end of the compensation piston. which is greater than the force exerted by the primary spring 105 on the piston 89 _o In this way, the piston 89 is essentially by the force of the secondary spring in the

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Shunted position held, which cancels the force of the primary spring to a considerable extent.

Thus, here too, the force of the primary spring in the final lifting position of the piston 89 is very significantly reduced and the pressure drop between inlet port 93 and outlet port 94 remains at the desired level low values

However, as soon as the piston of the associated control slide is moved into a working position, it flows from the Feed channel returned pressure medium into the return port 96 in order to move the compensation piston to the right move and restrict or shut off the flow to the outlet connection 94 and the feed connection 95 with the selected motor connection of the associated control spool <>

As soon as the pressure in the feed channel 95 rises when a load is overcome in the controlled working cylinder must, the pressure in the chamber 102 also increases in order to move the piston 101 into the inner end position, in the pin 107 acted upon the bottom of the recess 98. In this position, the piston 101 becomes practical

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part of the compensation piston 39 »so that the action the secondary spring 100 practically becomes Hullo Xn according to the feed position of the compensation piston Pig «5 thus practically only activates the primary spring 105 the piston 89, without counteracting by means of the secondary spring. This creates the desired one strong spring preload required for a precise regulation of the flow from the pump to the feed connection 95 °

As before, here too the compensation piston speaks to changes in the pressure difference between the pressure medium at the inlet port 93 and the returned pressure medium at return port 96 to the rotary fluid flow to change the supply connection according to these pressure fluctuations ο

From the above description and the accompanying drawings, those skilled in the art will recognize that the invention discloses a pressure compensation valve whose compensation piston can be held in the bypass position with relatively weak forces, but which is under a much greater spring force when it comes to the compensation piston move out of the feeding position _o

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ITLR skilled in the art It is also evident that the invention can be modified in deviation from the above description and modified ₀

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Claims (8)

Expectations A pressure compensation valve with a slide piston, which on a first piston surface from the inlet pressure is acted upon in the direction of a bypass position in which the entering at an inlet port Pressure medium in shunted to a feed port to an outlet port, and which at one second piston surface is acted upon in the opposite direction by a returned working pressure in the direction of a feed position in which the at the inlet connection incoming pressure medium is fed to the feed connection, characterized in that the Slide piston (26) is acted upon by a primary spring (40) in the direction of the feed position and a Secondary spring (41) is provided, which in the bypass position of the slide piston (26) with a Auxiliary piston arrangement (22) is switched on in such a way that its spring force corresponds to the spring force of the primary spring (40) counteracts and the spool (26) in the bypass position with significantly reduced spring force is supported. 309835/0394 2. Pressure compensation valve according to claim 1, characterized characterized in that the secondary spring (41) cooperates with an auxiliary piston (42) which, in the feed position of the slide piston (26), is the secondary spring (41) relieved. 3 * pressure compensation valve according to claim 1 and 2, characterized in that the auxiliary piston (42) is arranged coaxially to the slide piston (26) between the primary spring (40) and the secondary spring (41) 4 · Pressure compensation valve according to claim 1 to 3, characterized in that the primary deder (40) is made much stronger than the secondary spring (41). 5 pressure compensation valve according to claim 1 to 4, characterized in that the primary and secondary springs (40, 41) are in series with the slide piston (26) are switched so that the total force exerted by them (RT) is the same in the shunt position the product of the spring constants (R1 χ R2) divided by the sum of the spring constants R1 + R2). 309835/0394 6. Pressure compensation valve according to claim 1 to 5 » characterized in that the displacement of the auxiliary piston (42) in the feed position by the returned working pressure takes place » 7. Pressure compensation valve according to claim 1 to 6 » characterized in that the secondary spring (41) is in the bottom part (49) of one of the auxiliary pistons (42) Cylinder (46) rests, which is connected to the connection (29) for the returned working pressure is. 8. Pressure compensation valve according to claim 7 »characterized in that its slide piston (26) in a recess (43) adjacent to the auxiliary piston (42) contains the primary spring (40) so that this recess (43) is connected to a return connection and that the auxiliary piston (42) has an axial channel (57) which connects the recess (43) with the bottom part (47) of the cylinder (46) connects. 9 pressure compensation valve according to claims 7 and 8, characterized in that the opposite ends of the auxiliary piston (42) reflect the returned working pressure in the recess (42) and the bottom part (47) 309835/0394 of the cylinder (46) are exposed and that the auxiliary piston is designed as a stepped piston (42), works in a stepped cylinder (46) and its larger cross-section on that of the slide piston (26) has remote end. 309835/0394