DE2350380A1 - Control plunger for hydraulic motors - has piston with two operating positions with pressure compensation and reducing valves - Google Patents

Abstract

The slidable piston can move in a bore between two operating positions for selectively connecting the motor to the hydraulic inlet and return. A pressure compensation valve has a piston which in the first slide piston position controls the flow from the inlet to the feed channel according to variations in the pressure difference between a section in front of the slide piston and a section behind it. A pressure reducing valve, in the second slide piston position, controls the flow from the motor connection to the return and provides a fixed small pressure at the connection which is above the pressure at the return. A hydraulic operator relates to the pressure of the hydraulic fluid flowing from the feed channel to the motor connection in the first operating position.

Description

ff ΐ ¹ hydraulic motor

The invention relates to a control slide for single and double ir?: Lrksa®eh ^ draislische cylinders or other hydromotor® f which operates at constant speed regardless of the load acting on the engine

In the case of such control spools, a spool connects Seleistiv the Mötoranscirusses with the pressure medium inlet or the reflux .. Sine actuation of the motor with decreased Speed results when the spool is only partially shifted in the direction of the working position and there is a throttled inflow 2um the motor connection.

The object of the invention is to create a control slide of the aforementioned type _p with which the speed

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of the motor both on the inflow side and on the return side is very precisely controllable.

This object is achieved by a pressure congestion valve with a pressure-dependently displaceable piston which, in the first working position of the slide piston, controls the flow from the inlet to the feed channel depending on fluctuations in the pressure difference between a feed channel section upstream of the slide piston and a feed channel section downstream of the slide piston lying feed _{channel section regulates t} a pressure reducing valve, which in the second working position of the spool regulates the StrSmungsialttelfluss from the motor connection to the return flow and ensures a fixed low pressure at the motor connection, which is above the bracket on the return flow, and also a hydraulic actuating device that reacts to the pressure of the from the feed channel to the motor connection in the first working position of the slide piston responds to pressure medium flowing and ensures a substantially unhindered flow to the hydraulic motor connected to the motor connection.

In the case of control spools for double-acting hydraulic cylinders or motors, two pressure reducing valves are provided which restrict the return flow coming from the motor, its inflow but don't hinder.

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Further details and features of the invention result from the following detailed description and the accompanying drawing, in which a preferred Embodiment of a control slide according to the invention is shown in an axial section «.

The control slide 10 shown in the drawings contains in its housing 12 a bore 11 for a slide piston 13 »which is displaceable in two working positions in relation to the neutral or holding position shown ₉ which are on both sides of the neutral position ο

The control slide includes pressure medium inlet 14 "a pressure medium outlet 15 _g a feed channel with @ £ m" front section 16 between the J ^ ckmitteleixtl @ ® 14 BBi d @ r bore 11 and a rear section 17 "which is axially offset with respect to the front section in the Bore 11 opened in. The rear section 17 of the feed channel leads via an iasthaltendes check valve 18 to two opposite feed channel arms 19 and 20, which in turn lead to the bore 11 and open on opposite sides of the central bore part outside of the feed channel sections 16 and 17 o

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Control slides also include two Wotoranaohlußkanäle 21 and 22, which opened into the bore 11 outside the Speechkaaalarae 19 and 20 respectively or _{cut 0} 22 «

In the illustrated neutral position of the control slide, piston sections arranged in the vicinity of the valve piston ends block a connection between the Hotoranseblußkanäle and the feed duct or return duct arms feeding channel ο Am Solbenabsefcmitt 28 are JDroseelkerben provided 30 seun axially opening out to opposite sides and the possibility g @ bem ₉ the flow of pressure medium from the front Speisekanalaisseliisitt 16 rear portion 17 te the vessels! © ä © new rope-j \ rbeitsetellungen of STEU @ rse »Ieb © re to dose both sides üex leutrelposition.

If the Sehieberkolben into a right of Feutralstellung lying working position different ^ @ "wi & A _9, the pressure

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medium in the front feed channel section 16 via the bobbin 11 along the slide piston to the rear feed channel section 1? flow and then reach the feed channel arm 19 via the check valve 13, so that a connection via the bore 11 to the motor connection channel 21 and to the rod-side end of the working cylinder B 24 connected to the motor connection channel 21 is made possible o The pressure medium released at the head end of the cylinder 27 returns to the motor connection channel 22 back, from which it can flow freely via the bore 11 to the adjacent Bückflusskanalarm 27 _c

The aforementioned connections between the motor connection ducts and the supply and return ducts are reversed when the slide piston is moved to a working position to the left of the neutral position _{or the like}

The pressure medium inlet 14 and the pressure medium outlet 15 open axially apart into a bore 32 a pressure-dependently displaceable piston 35 of a pressure compensation valve 34o The pressure medium outlet 15 can be consider as a return channel, which is also connected to the pressure medium inlet a second control slide can be connected to the control slide described above

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downstream let. The pressure medium outlet is in any case 15, however, as shown, in the end with a line in connection to the pressure medium collecting container leads, which is provided for the control slide assembly.

The front feed channel section 16 also opens into the bore 32 of the pressure compensation valve 34 at one Zone that is adjacent to the pressure medium inlet 14 on the side that is remote from the pressure medium outlet 15 solder.

The opposite ends of the bore 32 are blocked with screw plugs 36 so that on opposite sides Ends of the bore cylinder 37 and 38 arise, which can work together with the opposite ends of the piston 33 · Sine screw pressure spring 39 in the cylinder acts on the piston 33 in its one boundary division, in which the piston 33 comes to rest against the visual plug 36 A circumferential groove ensures that the piston is in this position of the piston 33 for a connection within the bore 32 between the pressure medium inlet H and the front Section 16 of the feed channel *

In any position of the piston, however, the pressure medium can come from a pressure medium source, for example a

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Pump P through a radial opening 41 in the wall of the Piston 33 enter an axial channel 42 of piston 33, which leads to the cylinder 37 at the left end of the bore 32. As a result, it works coming from the pump® Pressure medium always on the left end of the compensation piston 33 to push the piston to the right into a position in which a free connection between the Pressure medium in Xass 14 and the pressure medium outlet 15 consists "

The last-mentioned state is present when the control slide piston 13 is in the neutral position. The peder 39 generates all the force - which counteracts the force that the pressure medium coming from the pump - in the cylinder! ' 37 © ffi Compeiaeationskolben 33 exercises. For this purpose, the di @ Druekfedes 39 contained! © cylinder 38 to the collecting container via * © ia @ BeItTOg 43, which is connected to the bore 11 at the intersection with the rear section 17 of the feed channel. This zone of the bore 11 is connected in the neutral position of the slide ^{piston 13 via channels 1} ′, to which a piston section 44 of the slide piston 13 with a reduced diameter, an annular widening 45 of the support 41 and a line 46 leading to the collecting container

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It is important to point out ₉ that even a slight displacement of the valve spool 13 from the neutral position in any direction has the consequence that the ventilation path for the cylinder 38 of the compensation valve containing the spring 39 is blocked o The relatively long cage section 47 of the spool, the lies with its left end in the bore enlargement 45, the Yerbindirag locked to the cylinder 38 through the formed reduced ^ diameter spool piston member 44 at a slight after leftward movement of the ski upper piston 13 from the üTeutrala "position out _β Similarly, occurs much shorter Piston section 48 of the valve piston 13 at the left end of the section 44 of the valve piston 13, which is designed with a reduced diameter, enters the bore 11 when the valve piston is moved slightly to the right from the neutral position. In this way, the cylinder 38 is opposite the ventilated bore extension 45 cordoned off

In every rope working position i @ s valve piston 13, in a metered amount from the Löfiaekmitteleinlaß to one of the working channel connections ilb © s? the front feed channel section 16, one or more throttle notches 30

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of the piston section 28 _p the rear feed channel section 17 and one of the feed channel lines 19 or 20 is passed on s there is a pressure difference between the feed channel sections 16 and 17 on opposite sides of the slide piston 13. The piston 33 of the pressure compensation valve 34 responds to this pressure difference "around at each." Metering position of the slide piston 13 either to increase the pressure in the front feed channel section 15 or to reduce it so that the pressure difference is kept at a constant value. In this way, a hydraulic motor controlled by a control slide can be kept in operation at a constant low speed _{or the like}

This operation results from the fact ₉ that the pump pressure in the forward supply duct portion 16 is implemented in the cylinder 37 at the left end of the piston 33 in eifce force by which the piston is displaced in one direction, the love sehlußfluß increased in the pressure medium outlet 15, and in correspondingly, the pressure medium flow to the feed channel section 16 becomes lower. “The fluid pressure in the bore 11 at the zone in which the rear feed channel section 17 merges is set at the other end of the piston 33 in the cylinder 38 to a force which is in the same direction as the spring 39 works

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and moves the piston in a sighting in which the earthquake flow between inlet and outlet is reduced, so that the Bruekmittelfluss to the front feed channel section 16 becomes larger with a corresponding increase in pressure.

The pressure in the bore 11 below the check valve 18 will understandably vary in accordance with the load of the motor 24 »If, for example, the The load on the cylinder 24 is greater, while a metered amount of pressure medium is applied to the head-side end of the working cylinder is supplied, the working cylinder 24 tends to a speed vex reduction with a corresponding Enlargement of the pressure in the actuating cylinder 38 of the compensation valve 34. In this way, the force acting on the right end of the piston 33 increases, to move men piston 33 in a direction 2u, in the the connection cross-section between inlet 14 and outlet 15 decreases, while at the same time the connection cross-section between pressure medium inlet 14 and the front Feed channel section 16 becomes larger in order to correct the situation again «

It is similar if the load on the working cylinder 24 should be less so that the pressure in this cylinder

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parent piston is "bestreit to move faster than desired. In this case, the result generated" · \ de pressure drop in the rear supply duct portion 17 increasing the pressure difference between the front and rear portions 16 ₉ 17 of feed channel _0, the piston 35 of the IDruckkoiapensationsventils speaks to the reduced pressure in the cylinder 38 characterized in that it moves to the right to the WebenschluSfluß between Binlaß and Auelaß to increase. This then results in a corrective © Yerminderung the supply pressure in the front Speisekanalabsehnitt 1 β _o

By keeping the pressure difference between the front section and the rear section of the feed channel at a fixed value, the Gteeobwittälgfesit üa working cylinder or motor remains at © la «, b @ © tti» * ®i * the value of the setting of the spool in any dosing position corresponds to »

The pressure compensation valve 34 thus influences more, or less the dosage of the pressure medium flow coming from the pump to the feed channel and from there su eitsem hydraulic motor via one or the other hot water connection point, which is connected with the help of the spool »

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According to the present invention, however, the "reflux of the pressure medium regulated by the controlled motor in a metered operation to prevent under certain working conditions drive the load of the engine » so that at any time a positive regulation of the speed, with which the motor works, is achieved »For this purpose, there are pressure reducing valves for the two motor connection ducts 21 and 22 50 and 51 provided

In the illustrated embodiment, the pressure reducing valves are in a housing 52, which is directly is placed on the housing 12 of the control slide over the openings of the motor connection channels 21,22. i) a these pressure reducing valves are equal to each other is sufficient it is only to describe the one pressure reducing valve from ρ, which the engine pressure medium return flow at the left engine connection channel 21 regulates "

The pressure reducing valve 50 has a bore 53 which is closed at its ends with screw plugs 54 and 55 so that pressure chambers 56 and 57 are formed at the ends of the bore 53. In the bore 53, a pressure-dependent piston 59 is displaceable, the end parts of which protrude into the chambers 5 and 57. Aa piston 59 is located

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sieve a central circumferential channel 60 ₉ which normally enables a connection between the arms 61 and 62 of the motor connection channel via the bore 53. The two arms 61 and 62 form a continuation of the associated motor connection channel 21 _β

Since the arm 61 is directly connected to the motor connection duct, it will hereinafter be referred to as the arm on the slide side axially spaced points in the bore 53 and are normally connected to one another via the Ifcafa-ügsrinne 60 of the piston 59 «

It is easy to overlook the fact that the housing 52 _9, the piston 59 and the arms 61 and 62 can be arranged at a distance from the housing of the control slide. The only important thing is that the two channel arms 61 and 62 form a motor connection line through which the Motor connection channel 21 is connected to one of the motor connections «

The pressure reducing valve also includes a peder 64 «die is in the pressure chamber 57 and the adjacent end of the

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-. 14 -

Piston 59 shown in the? usually existing inactive position pushes the opposite end of the piston 59 rests against the screw plug 54,

The left pressure chamber 56 is with the arm on the slide side 61 and thus connected to the motor connection channel 21 via a channel provided in the piston itself, to which a axial section 66 which opens into the chamber 56, and a radial arm 67 which leads to the arm 61 on the side of the slide valve. The connection channel 66,67 is constantly a connection between the pressure chamber 56 and the Motorahseblußkanal 21 so that the pressure medium in the Chamber 56 is under the motor connection pressure »

The pressure chamber 57 containing the Peäer is ventilated so that the piston can move to the right into the flow-restricting position when the pressure in the pressure chamber 56 rises. The pressure chamber 57 can be to the collecting container of the system ssu which the control slide heard aerate _e In the illustrated embodiment, is ventilated, however, the Speisekanalarmett 19 »20 of the rear Speisekanalabsehnittes 17 via a vent line 7O ₀ This vent line in any desired manner is schematically shown as a

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Axialbobrung 71 of the threaded plug 55 and an axial bore 72 in the holding-Sehraubstopf en 73 of the Hückschlagven- \ TILs 18ο About this Belüftungaleitung 70 communicates the pressure chamber 57 with a recess 74 inside the threaded plug 73 in conjunction "Sine angle bore 75 ensures the non-return valve 13 for a Connection of the recess 74 to the rear feed channel arms 19 ₉ 20 ₀

In the neutral position of the spool 13, the rear feed _{ducts 19 9} 20 plus the return duct 26 are ventilated ο This ventilation takes place via a duct 76 of the control slide 13 with radial arms 77 and 78 at the opposite inlets a connection to the rear feed duct arm 19 and the SüökfluBkanal 26 manufactures.

In this way, the spring-loaded pressure chamber 37 of the pressure reducing valve is ventilated via the back-like arms 19, 20 of the rear feed channel section and the channel 76 of the slide piston in the neutral position 61 xmü thus also respond in the chamber 56 _{9 in} order to move in the direction reducing the flow rate in order to

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to cause change in the motor inlet channel 21 to a value, which "is determined by the force of the spring 64, which counteracted the movement of the piston 59

If "for example, attacking a spring in accordance with a force of 14 atm on the piston 59, that! Pressure reducing valve for pressure reduction in the motor connecting channel 21 provides _s atmospheres to about 14 while otherwise the pressure may with high loads on the engine to a value of 200 atmospheres rise could

It follows from ₉ that at a pressure in the return channel 26 of 0 atü, the seepage to the return channel along the wall of the bore 11 containing the valve piston 13 from the motor connection 21 will only be 1/15 of the value ρ that would be present if one were in the The holding or neutral position of the spool would leave an unreduced pressure of 210 atmospheres.In other words: with a pressure difference between return duct 26 and motor connection channel 21 of 210 atmospheres, the seepage loss would be considerably greater than with a pressure difference of only 14 atmospheres between the named connections, ,

The pressure reducing valve 50 keeps the pressure difference between

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Rüekflusskanal 26 and Motoransohlußkanal 21 on one

the desired low value as long as the seepage loss along the left piston section of the piston 59 aum the motor connection channel is not greater than the seepage loss from the motor connection channel 21 along the Sehleberfcolbens to the adjacent return flow channel 26 _Q. This condition can normally be met by placing the piston 59 between the confluence of the engine-side and slide-side arms 61 and 62 led to a sufficient length in the cylinder

Means of the pressure reducing valve described can be the seeping down of pressure medium from any motor connection passage for Hückflußkanal 26 or "27 in the Hfeutral- or holding position of the spool 13 at a minimum value hold ₀

In every working position of the spool Ί3 * in the a partial connection between motor connection duct 21 and backflow channel 26 is effected * the piston 59 speaks of the pressure reducing valve to any load-related pressure increase in the motor connection channel above that caused by the spring 64 fixed pressure from 14 atm on by a near right directed movement through which the pressure medium flow from

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motor-side arm 62 to sebiebersei term arm 61 dee Motor connection 21 is so "restricted" that it to restore the desired 14 atmospheric pressure difference between motor connection duct 21 and return duct 26 comes ο This results in "end at every I" to increase the pressure in the Moforan connection channel 21 due a tendency of the load on the controlled cylinder in increasingly downward "move, another automatic Haehregulation of the piston 59 in a "backflow" restricting direction, so that the pressure at the motor connection channel 21 is kept at a constant low value and the speed at which the pressure medium is released the cylinder, essentially the speed becomes the same with which the pressure medium is delivered to the cylinder ρ

By maintaining a pressure difference between Hotoransohlußkanal 21 and RiiekfluSkanal 26 on one Worth? On only 14 atu are the axial back-up forces that normally at the spool 13 due to a high fluid flow along the spool in

to "fci * ö" fceii Direction towards the reflux canal to a considerable extent reduced »Just as important, however, is the fact that in this way the throttle area of the spool

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is hereditarily enlarged "

\ It is still to be mentioned; that the pressure reducing valves do not need to disturb the flow of fluid from the feed _{channel arms 19 or 20. sum selected motor connection and to the connected hydraulic motor 0} For this purpose, either the motor connection or the slide-side arm 61 can be connected to the motor-side arm 62 via a line not shown, which runs in the siphon to the pressure reducing valve and contains a check valve which prevents the pressure reducing valve from being bypassed by the return flow coming from the motor to the return flow channel of the control slide «,

The same result with the illustrated arrangement available in the vent line 70 to the feed channel arms 19 and 20 communicates ₀ These arms 19 and 20 include, always under high pressure pressure medium; when the spool is in one of its working positions. If, for example, pressure medium under high pressure is fed to the engine connection duct, this high pressure medium also flows through the ventilation line 70 to the chamber of the left pressure reducer containing a spring.

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valve 5O to the piston 59 in a wide open position to move in which the flow from the motor connection channel 21 to the arms on the valve side and on the motor side 61,62 is not disabled.

An essential feature of the invention is that through the connection of the pedestal chambers of the two pressure reducing valves with the feed channel arms 19 and 20 a Compensation or flow coordination effect arises can normally only be achieved with much more complicated equalization valves »

Let us assume, for example, that the sight Bear piston 15 is shifted to the left to the of the Pump coming pressure medium to the feed channel arm 20 and from there to the motor connection 22 and to the head-side bottom of the cylinder 24, while at the same time the pressure medium emerging at the rod-side end of the cylinder can return via the motor connection duct 21 to the return duct 26 »At this point in time, the Speisedruek also from the pedal chambers 57 of both pressure reducing valves perceived thanks to the ventilation line 70. The pressure then rises immediately at the cylinder head and in the Feed channel arms 19 »20 when the piston of the pressure reducer

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valve "prevents limiting position shifts ₈ in that the rod side output at the cylinder pressure means obtains a speed _v which is high enough to accommodate the feeding pressure medium at the head-side end of the cylinder" 50 located in a the flow This increase in pressure is also described in chamber 56 erfaßt- the pressure reducing valve 50 so that the piston of Iteackminöerrentils fcung in valve opening the Rieh- ■ or moved du3? chflußkoordiQierend © r direction _s so wirä eggs reflux by controlled .Arbeit ssylind he teann done as quickly ^ as in a given setting cies control slide 13 releases the pressure medium from the pump «

From the above description and the attached Drawing is apparent to the ^ aehsaann that the invention discloses a control valve assembly with which see the operating speed of a controlled Hydro ~ motors goose can be steered particularly well »

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Claims (1)

Claims j 1 « J Control valve for hydraulic valves with a slide piston that can be moved between two working positions in a ^^^ bore for the selective connection of the motor connection with the pressure medium inlet and the return flow, characterized by a pressure compensation valve (34) with a pressure-dependently displaceable piston (33 ), which in the first working position of the slide »piston controls the flow from the inlet (14) to the feed channel (16,17,19,21) depending on fluctuations in the pressure difference between a feed channel section (16) in the direction of flow in front of the slide valve piston (13) and a feed channel section (17) located downstream of the slide piston (13) regulates a pressure reducing valve (50) which, in the second working position of the Schißber piston (13), regulates the flow of fluid from the motor connection (62,61,21) to the return flow (26) and at the motor outlet (62) provides a fixed low pressure which is above the pressure at the return flow (ZS) , and fer ner a hydraulic actuating device / which reacts to the pressure of the pressure medium flowing from the feed channel (21) to the motor connection in the first working position of the slide piston (13) 5 0 981 6/0090
BATH ORIGINAL responds and for an essentially unrestricted flow to the one connected to the motor connection £ 2) Hydraulic motor (24) ensures, 2 "spool according to claim 1 for two-sided loadable hydraulic motors with two Motoranschlüasen, of which one DruckmitteleinlaS and aer other is connected to the reflux in the operating positions with the, characterized in that for each of the two motor terminals (21,22), a pressure reducing valve ( 50,51) is provided in order to control the return flow, and that both pressure reducing valves (50,51) \ hydraulic actuating devices (56,57) which ensure an essentially unimpeded flow to the connected motor (24). 3, control slide according to claim 1 or 2, characterized in that that the pressure reducing valves (50,51) contain a valve piston (59) in the flow-through valve Direction through increasing pressure in the steering wheel * slide-side connection (61) of the pressure reducing valve ^ (50 »51) is moved and a spring (64) is applied in the opposite direction · 509816/0090
BATHROOM ORIGINAL ¹ 4 · spool according to claim 2 and 3 »characterized in that the pressure-reducing valves (50,51) are provided with a transmitting only flow Erich Tung connected to the hydraulic motor (24) shunt · 509816/0090 BATH ORIGINAL