DE2223965A1 - Hydraulic control valve assembly - Google Patents

Description

Hydraulic control valve assembly

The invention relates to a hydraulic control valve assembly for the operation of fluid motors and in particular such control valves, with which the operating speed of the fluid motors very much can be set precisely: even if the from Motor moving load tends to move the motor faster than is desired.

It is well known that fluid motors, for example Hydraulic cylinders through which the load acting there can be moved. For example, the loading arms of backhoe excavators and front loaders are very heavy loads, which generally have to be raised and lowered according to the settings of the control valves. At the Lowering such a charging swing θ. directs the control valve the pressure medium coming from the pump to one end of the cylinder and also provides a connection between the the other end of the cylinder and the sump of the system. The loading arm tilts under the influence of gravity to move uncontrollably and with increasing speed downwards. Often it reaches the loading arm such a high speed that the increasing

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Chamber of the cylinder not fast enough with pressure medium can be topped up from the pump. As soon as this happens, a negative pressure arises in the expanding cylinder chamber, ο that the precise control of the loading arm is lost goes until the cylinder is refilled with pressure medium 1st.

When it comes to loading arms that can also be moved sideways, as is the case with loading arms from Excavation is the case, inertial forces can cause the load to move the drive cylinder in one direction or the other This also makes it extremely difficult or even impossible to precisely set the swivel speed of the loading arm to control.

A wide variety of throttle arrangements have been proposed in the past in order to be able to control the movement of heavy loads with hydraulic cylinders more precisely. The previously known throttle arrangements are, however, neatly complex and expensive.

The object of the present invention is therefore to provide a particularly simple and inexpensive hydraulic control valve arrangement, with which the working speed can be controlled extremely well by hydraulic motors, even with very heavy loads.

The above object is achieved according to the invention in that at least one of the motor connection ducts of the control valve arrangement occurs in one of the controlled motor

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Load pressure regulated pressure reducing valve is arranged »which the pressure when the pressure medium flowing back from the engine to the outlet behind the pressure reducing valve at a small ** essentially constant value above the outlet pressure.

In addition to the pressure reducing valve provided according to the invention To set operation when the motor connection channel controlled by it is fed can, according to the invention, either be at Druckini ttelventil a shunt with a check valve can be provided or there is a dated on the pressure reducing valve Hydraulic actuating piston that can be acted upon by feed pressure is provided, which moves the valve body of the pressure reducing valve in Direction to inactive position applied

Preferably, the pressure reducing valve according to the invention is as Piston valve formed, which has a central circumferential groove and the receiving its slide piston Bore allows a passage in the motor connection channel and has hydraulic actuating pistons at its ends, one of which is adjacent to a pressure chamber exposed to the discharge pressure downstream of the pressure reducing valve and the other is adjacent to a pressure chamber which contains the return spring. second pressure chamber receive the feed pressure in the feed position of the main control valve and in the neutral holding position and the Be ventilated outflow position.

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

In the drawings show:

Pig. 1 shows an axial component through a hydraulic control slide according to the invention,

Pig, 2 shows a broken axial section corresponding to the left part of FIG. 1 with a spool in a working position and

Pig »3 an axial sonicity, which a! Ceil der Figure 1 corresponds and explains a modified AusfUhrungsforn of the invention «

The essentially conventionally designed hydraulic control slide 5 consists of a housing 6, in the bore 7 of which a slide piston 8 is axially displaceable · From the in Pig. I illustrated In the neutral or holding position, the valve spool can be moved in two opposite directions in Ar- ' Postpone jobs, one of which is in Pig · 2 is shown. In the working position

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one of the motor connections 9 and 10 with the (not shown) pressure medium inlet connected, at the it is a high pressure feed or bridge duct Ii acts. Xn the working position is on the same side second motor connection with a (not shown) Collecting tank connected via an adjacent Aualaßkanal.

In the case of the control spool shown, the «· lass insoles 12 and 15 into the stop hole 7 at widely spaced locations is U-shaped; its leg parts 11 * and 11b open into the bore 7 at points which are offset inwardly with respect to the outlet ports 12 and 15. The motor connections srt & en with the bore 7 each in connection between one of the outlet ports and the leg of the adjacent one Bridge canal are »-

In all working positions of the valve piston 8 is Pressure medium coming from the inlet into the high pressure bridge channel 11 is branched off in the usual way via a load-holding check valve 15. Screw plug en H held, which is directed downwards

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«· 6

Screwed into the case 1st and one inside Has recess 15 which is connected to the bridge channel 11 connected is »Sin stem 16 of the check valve is in the recess 15 of the Sohraubatopfene, ge · performs in order to be able to open and close the valve seat by its axial movement. In the usual way is in the RUekschlagventllsohaft a kinked channel 17, which the inside of the recess connects to the bridge channel 11, so that when opening of the check valve, the pressure medium can be released from the recess 1 into the bridge channel 11 kanno Bin weak leather (not shown) in the recess 15 acts on the check valve 1? in 8oHU «ei * dittatg <,

In the housing 6 of the control slide there are pressure reducing valves 20 or «21 _{β directly above the openings of the motor connections 9 and 10.}

Pressure reducing valve 20 includes a housing 22 a through hole 23, which is at the opposite * lying bathing old plugs 24 and 25 are closed, the bore parts adjacent to the plugs 24 and 25 form chambers 26 and "27" In the bore 23 there is a pressure sensor

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piston 29, which engages with its end parts in the chambers 26 and 27 and in its middle has a circumferential groove 30, which normally via the bore 23 as an extension of the associated motor connection 9 establishes a connection between the pressure reducing valve solenoid 31 and 32 ₀ The connection 31 is directly with the motor connection 9 and the bore 23 at a small axial distance toil of the confluence of the other connection j2 in connection _ö

Between the Sohrauble 25 and the neighboring one At the end of the piston 29 is a helical compression spring 34 which turns the piston 29 into the inactive Normal position presses, welohe through the stopper What is defined is “In this normal position of the piston the circumferential groove 30 bridges both junctions of the connections 31 and 32 in the bore 23, so that the connection 32 free with the associated motor socket 9 is connected »

The grain 26 lying at the left end of the piston 29 is connected to the connection 31 and the motor connection 9 via channels in the piston. Belongs to these connection channels an axially directed channel 36 which opens into the Kaamer 26 and a radial channel part 37 which leads into the connection 31 empties and is constantly connected to the

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Motor connection 9 ensured. For this reason, the pressure medium in the chamber 26 is always the same Pressure like the motor connection 9 «,

The chamber at the other end of the piston 29 is ventilated so that the piston 29 can move to the right depending on the pressure in the chamber 26. The chamber 27 can be connected in any desired manner to the collecting container of the system when the spool is one · however, the vent may also lead to Brüokenkanal 11, including providing a Belüftungeleitung 40 in Steuersohlebergehäuse 6 θθΙβ germ _f "su rich axial bores bzwβ 42 of the two screw plug 25 or" 14 performs the Belüftungsleitting 40 thus provides a Connection ▼ on the chamber 27 to the recess 15 of the dust plug 14 and thus via the angled channel 17 of the check valve 15 with the high pressure bridge channel 11 «

According to the present invention is located in Sohieberkolben 8 a channel 44 with axially spaced apart radial branches 45, one of which connects to the leg 11a of the Hoohdruok bridge canal 11 and the other is used to connect to the return flow channel 12 when the control slide piston 8 in the neutral or holding position

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is located «, By such a ventilation of the Brüokenkanal the chamber 27 of the pressure reducing valve is also ventilated in the holding position of the valve piston 8 »so that the piston 29 can respond to the load pressure in the chamber 26 by moving to the right reduce the pressure in the motor connection 9 to a value au, which depends on the force of the spring 34, the acted on the piston 29

If, for example, the spring is set for a pressure of 14 atmospheres, the pressure reducing valve ensures that the pressure in the Hotoransohlufi 9 is reduced to about & tü, whereas the pressure occurring there can otherwise reach values that are 210 atmospheres with a heavily loaded, controlled cylinder It follows that at zero pressure in the adjacent outlet connection 12 the seepage along the wall of the bore 7 from the motor connection 9 to the outlet connection 12 is only 1/15 of the value that would otherwise be set for the Sioker flow if the A non-reduced pressure of 210 tu in the holding position of the valve piston to the motor inlet of the valve body would allow _{0 In} other words, the seepage flow at 210 atm differential pressure between outlet port 12 and motor port 9 is much greater than the seepage flow at only 14 att ^: Differential pressure between

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the named connections »

The pressure reducing valve 20 provides for the Upright * pose this desired low differential pressure between the A _n schlttssen 9 and 12 in the Heutralstellung of Sohieberkolbens 8 as long as the Siokerf Luss along the left piston section dee piston 29 sum Mötoransohluß 9 is not greater than the percolation * f The flow from the motor connection 9 "to the adjacent outlet channel 12 along the control slide piston 8 _O Bios can normally be achieved by making the guide of the Xolbone 29 along the wall of the bore 23 between the connections 31 and 32 sufficiently long"

The pressure reducing valve according to the invention provides a Reduction of the pressure fluid seepage from the hot water connections to the neighboring air connection connections along the control spool 8 in its neutral or stop o

Fig. 2 shows the control slide piston 8 in one Working position for which only accepted for explanation should be that in this working position that coming from a single-acting hydraulic cylinder Pressure medium via the motor connection 9 to the outlet channel 12 o The spool is not in its left

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Endetellung been taken, but it is a TeilversteHung left the neutral position has been chosen to reflux for Auslaßansohluß 12 au dose, "These are the usual regulation of the Hotorgeschwindigkeit, d _o h _e in this case the sink rate at which the load on the cylinder moved downwards

If θβ is a very large weight with the load \ iffi controlled by the cylinder , which tends to drop with increasing speed »the pressure medium flowing back is driven at a correspondingly greater speed through the metering opening, which is set with the control slide piston With the slide "piston 8 you can only throttle in a very narrow area, provided that it is the throttling on the spool notches that are provided in the piston sections to regulate the return flow"

The above problem is solved for the motor connection 9 by the pressure reducing valve 20. Ee is again assumed that the spring 34 exerts a pressure of 14 at ti on the piston 29 to hold it in the wide-open or inactive position in which the pressure medium may enter from the terminal 32 is exposed in the motor terminal 9 ₀ The piston 29 speaks then on the pressure increase in the motor connection 9 to a value above

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14 * tü and if this pressure in the Kanner 26 is adjusted to the right in Sohließrlchtu ^ g in order to restrict the connection between the connection 32. and the Motbransohluß 9 as much as it is necessary ₉ to the desired Dlfferenedruck von H Restore the air in the motor connection 9 and in the adjacent outlet duct 12 "Any tendency for an increase in pressure in the hot water connection 9 due to the lumbar load on the controlled cylinder to move downwards at increasing speed" is thus countered by further automatic adjustment of the Solbens 29 in the closing direction _f whereby the pressure in the Hotoransohluß 9 is kept at a constant low value, which depends on the strength of the spring 34

There are other advantages that should be mentioned through the use of the pressure reducing valve according to the invention If, for example, there is only a pressure difference of 14 «tti between the connections 9 and 12, the axial reaction forces on the slide piston, which result from the fact that the Pressurized fluid under high pressure flows along the valve piston to the outlet port, but is also significantly reduced the Xateaohe that the throttle path length of the spool is greatly increased,

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If the pressure reducing valve 20 improves the speed control for the lowering movement of a single-acting cylinder (or the speed of a rotary hydraulic motor fed from the other motor control unit 13), this must not interfere with the pressure medium supply from the pump to a cylinder or other electric motor When the cutting piston 8 is in a working position ₉ in the outer motor connection 9 is connected to the adjacent leg ü® & Hochdruok bridge channel 11 and a load has to be lifted o For this purpose, the ventilation air 4O ₉ serves as the collector 27 of the Brackminder valve also connects the high pressure back channel 11 with making the piston 29 insensitive to the pump delivery pressure which is present when the cylinder is fed via the motor connection 9 «. This effect arises through the fact that the pressure medium is maintained in the chamber 27 at the same high pressure in this 3FaIIe, such as is present in Brüokenkanal. 11, D _e r piston 29 thus remains in wide open Finished slope, represented by the System on screw plug 24 is defined ο

Pressure reducing valves 20 and 21 according to FIG. 3iig. 1 can be used for both motor connections of a ¹ control valve *. turn, which is used for reversible bydromomotors, both

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For example, double-acting hydraulic key actuators. The mode of operation of the pressure reducing valve 21 is the same as that of the pressure reducing valve described above it moves into a position in which the motor connector 10 connects to the adjacent connector 13 of the exhaust port. The ventilation line to the bridge duct 11 makes the valve 21 ineffective if the associated motor connection 10 is connected to the leg 11b of the bridge duct via the control slide piston _{or the like}

Pig. 3 shows another possibility, the unimpeded. To ensure the flow of the pressurized medium under high pressure from the pump to a controlled hydraulic motor via one of the motor connections 9 or 10 of the control slide, without disturbances from the pressure reducing valve occurring when the chamber 27 occupied by the Seder eu a collecting container or sum of the opposite motor connection 10 Place the bridge channel 11 is ventilated «. As sohematisoh shown in Pig x 3, provided with a check valve 51 ffebensohlußleitung can provide for 50 parallel connects the terminals 31 and 32 Eum piston 29th The check valve 51 in the bypass

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is used so that a flow from the AaaatHusaA 2mm connection 32 is enabled regardless of the position te © 29 in the pressure reducing valve, "% Äa?" and the opposite flow is prevented by the shunt _e

It should also be mentioned that the auxiliary line 50 with check valve 51 in the housing of the pressure reducing valve can be accommodated if necessary «Velvet Corresponding the pressure reducing valves in the Qeh & use 6 of the control spool itself or fix it there with screws »

From the foregoing description and the accompanying drawings, the trader _{9 recognizes} that the present invention discloses an extremely simple but effective means of improving the speed control of hydraulic motors controlled by the control slides by means of a pressure reducing valve.

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Claims (1)

Claims [1. hydraulic control valve arrangement, characterized in that that at least in one of the motor connection channels (9 * 10) a pressure reducing valve (20,21) regulated by the load pressure occurring on the controlled motor is arranged, which when from the engine to the outlet (12, 13) rttckfließendem pressure medium, the pressure behind the Pressure reducing valve (20, 21) on a small, essentially constant, above the outlet pressure value. 2. Control valve arrangement according to claim 1, characterized in that the pressure reducing valve (20, 21) is displaceable between an inactive position in which the flow in the Motoraneohlußkanal (21 , 32) is not impaired, and a working position in which the Durohfluß of the engine to the engine outlet channel (32, 31f 9) is throttled depending on the discharge pressure at the engine outlet »1 5 * Steuervtntilanerdnun * according to claim 1 and 2 »thereby gek «an * ti paves the way for the pressure child valve (20, 21) to have a hydraulic actuation piston (29) is omitted, the ÖtrÖBKinfeMiddeldruck la MotoreaaschlußkeneJ. (31) la Drainage behind the pressure reducing valve (20, 21) is exposed and the valve body of the DrtiekftittderrentlXe (20,21) against a return spring (34) in the closed direction. 20 98 50/0767 «Wi **. “HiflQTfB 4. Control valve arrangement according to claim 1 to 3 »characterized in that the pressure reducing valve (20» 21), is provided with a shunt (50) which is a Contains check valve (51), which in the direction of flow from the controlled motor to the motor connection (31) locks * 5. Control valve arrangement according to claim 1 to 3 »characterized in that the pressure reducing valve (2O ₉ 21) contains a hydraulic actuating piston (30) which can be hit by the Spelsedruck« which acts on the valve body of the pressure reducing valve (20, 21) in the direction of the inactive position « 6. Control valve arrangement according to claim 1 to 5, characterized characterized in that the pressure reducing valve (20, 21) is designed as a piston slide which has a middle Ümfangsrinne and its slide disks receiving bore (23) allows a passage in the engine connection channel (31t 32) and at its ends hydraulic actuating piston (29, 30), one of which (29) to one of the discharge pressure behind d Pressure reducing valve (20, 21) exposed pressure chamber (26) and the other (30) is adjacent to a pressure chamber (27) which contains the return spring (34). 209850/0767 OR] SlHAL 7. Control valve arrangement according to claim 6, characterized characterized in that the second pressure chamber (27) is connected to the control valve (7, 8) via a line (40) is connected and in its feed position receives the feed pressure and in its discharge position is ventilated. 8. Control valve arrangement according to claim 7 »characterized in that the second pressure chamber (27) also is vented in the neutral holding position of the control valve (7, 8). 9. Control valve arrangement according to claim 8, characterized in that the control valve (7, 8) has a Contains control channel (44, 45), which in the neutral holding position of the control valve (7, 8) with the Connection line (40) of the second pressure chamber (27) connected feed channel (11) of the control valve (7,8) vented to outlet (12) »' 10. Control valve arrangement according to claim 1 to 9, characterized characterized in that the pressure reducing valve (20, 21) in or on the housing (6) is a piston valve (7 * 8) trained control valve is arranged and the valve body (29,30) of the pressure reducing valve (20,21) designed as a slide piston (23) across the motor connection duct (32,31 »9) parallel to the Axis of the control valve piston (8) extends 209850/0767 Blank page