EP0676547B1 - Flow control device for a high pressure hydraulic system and a valve for a load-lowering brake - Google Patents

Abstract

The quantity regulator for high pressure hydraulics has pressure medium flowing to and from a hydraulic actuator limited independently of pressure and/or load alterations. A measurement diaphragm (9) is incorporated which for each flow direction has a pressure balance measurement diaphragm (25-29) adjusting the pressure difference indicated by the measurement diaphragm. At least one conduit branches off the hydraulic circuit. The measurement diaphragm with the two pressure balance regulating diaphragms are arranged in a two-direction sink brake valve with exclusive two-way flow regulating function in a section of a work pressure conduit. <IMAGE>

Description

The invention relates to a quantity control device according to the preamble of claim 1 and a Lowering brake valve in the preamble of claim 7 specified type.

In the magazine "HYDRAULICS AND PNEUMATICS", June 1964, pp. 72 to 75 two-way flow controllers are explained, which has an orifice and a regulating pressure regulator orifice included and from a predetermined response pressure the pressure medium quantity independent of pressure changes keep constant. 1, 2, 4 and 8 is a Two-way flow regulator arranged in the working pressure line. 3, 5, 6, 7 is the two-way flow controller arranged in a bypass line to the tank. In the working pressure line arranged two-way flow controllers often used as so-called counterbalance valves the maximum movement speed of a hydro consumer limit, either in one or in the other flow direction, with the current regulator Part of a flow control device for high pressure hydraulics is.

A quantity control device known from DE-A-39 38 560 limits the speed of a one-way load Hydro consumer in both directions of movement in different ways. The quantity control device namely forms a two-way flow controller for Lowering movements and a three-way flow regulator for lifting movements. A common one when lifting and lowering in orifice in the same direction of flow is assigned to two parallel pressure regulator regulating orifices.

This flow control device has a complicated structure and only for one powered by the pump Hydro consumer useful, when controlling it when Lifting pressure medium flowing to the tank does not matter plays. With several from a common pressure source this is inappropriate for supplied consumers because that pressure medium flowing to the tank supplies others Consumers affected. With a lifting device like one Lift truck, especially an electrically powered one Forklift trucks, if this flow control device were not practical, because of what is pumped to the tank when lifting Pressure medium electrical energy is wasted or at the supply of other parallel consumers of pressure medium is missing.

With lifting devices, especially forklifts, are mostly several hydro consumers are provided, at least of which one is subordinate in the sense that it has no load lifting and has to perform lowering movements, but for movement control one essentially always the same Load moving device component is used. For example this would be a double-acting hydraulic cylinder for swiveling the lifting device back and forth, the is directionally controlled via a directional control valve. The Swiveling movement is at maximum speed in each direction limited. In more modern lifting devices this Type is also a speed-controlled pump in the hydraulic circuit usual, the delivery rate of the pump speed is proportional and can be regulated in such a way that they practically from standstill with increasing speed delivers an increasing output. With the speed-controlled Subordinate hydraulic consumer can pump in the respective one, selected by the directional valve Direction of movement up to its limit speed start up. The limit speed is determined by a Lowering brake observed in each direction. For the two directions of movement two lowering brake valves are provided, each of which flows out in its working pressure line Pressure medium amount limited while moving in the direction of inflow opens without throttling. The construction effort of two Lowering brakes in the working pressure lines is high because one orifice plate and one for each flow direction Pressure compensator orifice plate and a bypass for the unthrottled Flow are needed.

In a hydraulic known from DE-A-34 22 978 Control device of a double-acting Hydro consumer is in the on the piston side Working chamber of the hydraulic consumer connected Work management included a single control panel that alternately with an orifice plate of two in the direction Control valve provided measuring orifices cooperates, in each case in one flow direction Quantity dependence on the deflection of the directional control valve to regulate, either that of the piston side Incoming or out of the working chamber quantity flowing out of the piston-side working chamber. Because of of the two, alternately assigned to the only control panel Orifice plates also become a multi-position directional control valve for swapping the pressure compensator control pressures needed to the pressure compensator in each flow direction to control accordingly. The pressure compensator is also express of the directional control valve containing the orifice plates and the multi-position directional control valve are structurally separate. This requires considerable construction effort and considerable circuit and space requirements.

Further state of the art for technological Background is contained in: DE-A-31 39 944, FR-A-25 51 171, MACHINE DESIGN, July 18, 1963, Cleveland, US, pp. 168-184, and DE-A-36 05 980.

The invention has for its object a quantity control device and a lowering brake valve from the DE-A-39 38 560 to create known type in which the Speed limit of the hydro consumer in both directions of movement with little structural effort and reduced circuit and space requirements possible is.

The object is achieved with the Quantity control device according to claim 1 or the counterbalance valve solved according to claim 7.

The flow control device can despite Speed limit of the hydro consumer in no unnecessary pressure medium in both directions of movement stream unused. Other intended in parallel As a result, consumers become Control process of the aforementioned hydro consumer properly supplied. In the event that no other Hydro consumer is operated simultaneously or is present, can be the one usually provided Safety valve in the pressure supply for draining excess pressure medium are used. The Flow control device is particularly suitable for Cooperation with a speed-controlled pump that a speed control until the intervention of the Quantity control device enables and also with several Consumers the required delivery rate provides. Be next to the one with the Flow control device monitored hydraulic consumers no other hydraulic consumers actuated, then the speed-controlled pump only the currently necessary Deliver flow rate so that no pump drive energy is wasted. This is particularly the case with lifting devices advantageous whose hydraulic pump from a battery is supplied.

With the bidirectional lowering brake valve, both are two-way flow regulators with a common orifice in one and the same working pressure line. It will thereby reducing the construction effort and the space requirement. An intervention in the other working pressure line not applicable. Despite the quantity regulation or Speed limit for both directions of movement no excess pressure medium from the hydraulic consumer wasted because there is none in the two-way flow controller function Pressure medium to the tank is drained.

The quantity control device according to claim 2 used excess pressure medium for the supply at least of another hydro consumer. It could be excess Pressure over the Safety pressure relief valve can be drained.

Processed in the embodiment according to claim 3 the subordinate hydro consumer only so much pressure medium, how the pressure compensator control panel lets through. From that priority, other hydro consumers, whose Operated by the subordinate and in both directions Hydro consumer limited to maximum speeds is not affected.

In the embodiment according to claim 4, the Pump only as much pressure medium ready as that Pressure compensator control orifice at the speed limit needs. The speed can be reduced up to this delivery rate of the hydraulic consumer by means of the pump speed adjust. Only then will the pump deliver more Pressure medium when supplying additional hydraulic consumers are.

In the embodiment according to claim 5, means of the directional control valve the respective direction of movement of the hydro consumer selected. The quantity control device is in every direction of movement of the hydro consumer effective.

In the embodiment according to claim 6, the quantity control device in a single working pressure line housed. Nevertheless, the speed of movement of the hydro consumer in both directions of movement limited.

A structurally simple, compact and reliable Embodiment of the lowering brake valve goes from claim 8 forth. The two pressure compensator control orifices are designed that they are open together in the normal position and each in the direction of flow they monitor from the open position towards its shut-off position curtail. This avoids unnecessary flow losses at low speed of the hydro consumer.

Wear to the structural simplicity of the lowering brake valve the features of claim 9.

In the embodiment according to claim 10 is on construction simple way for each flow direction the same Volume control reached. The common rule spring can be accommodated to save space. The lowering brake valve has only a few individual parts.

With regard to smooth control movements of the control piston the embodiment according to claim 11 is appropriate.

In the embodiment according to claim 12, the union nut a double function, since on the one hand it Orifice plate secures and on the other hand the stop for the Rule spring forms.

An alternative embodiment results from claim 13 forth. Here are different for both directions of flow Adjustable speeds that are independent let each other change.

In the embodiment according to claim 14, the Passages housed in a small space to save space. Nevertheless, the control behavior is clean.

The embodiment according to claim 15 is special space-saving. The one integrated into the screw-in housing Lowering brake valve is a unit that into the working pressure line or a channel of the Hydro consumer screwed.

Fig. 1

eine hydraulische Steuervorrichtung als Blockschaltbild,

Fig. 2

einen Längsschnitt durch eine Mengenregelvorrichtung bzw. ein Senkbremsventil, das in Fig. 1 symbolisch dargestellt ist, in der Normalstellung,

Fig. 3

die linke Hälfte eines Längsschnitts des Senkbremsventils von Fig. 2 in einer Regelstellung, und

Fig. 4

die rechte Hälfte eines Längsschnittes desselben Senkbremsventils in einer anderen Regelstellung.

Embodiments of the subject matter of the invention are explained with the aid of the drawing. Show it:

Fig. 1

a hydraulic control device as a block diagram,

Fig. 2

2 shows a longitudinal section through a quantity control device or a lowering brake valve, which is shown symbolically in FIG. 1, in the normal position,

Fig. 3

the left half of a longitudinal section of the lowering brake valve of Fig. 2 in a control position, and

Fig. 4

the right half of a longitudinal section of the same counterbalance valve in a different control position.

A hydraulic control device S according to Fig. 1, e.g. a lifting device, such as a forklift or forklift, has a pump P sucking from a tank T, which a pump line 1 feeds. A tank line leads to the tank 2. Between the pump and tank lines 1, 2 a safety pressure relief valve 3 is provided. The pump P can be a speed-controlled pump, the Flow rate is proportional to the pump speed. A Hydro consumer V, e.g. a double-acting hydraulic cylinder 5, with a piston side and a piston rod side Working chamber 6, 7 is via working pressure lines 3, 4 to a directional control valve W (4/3-way control valve with blocked zero position) connected, with which the direction of movement of the hydro consumer 5 is adjustable.

In the working pressure line 3 is a flow control device M, additionally in the form of a Two-way lowering brake valve Z, provided.

In addition, another hydro consumer V1 is over a working pressure line 8 and another directional control valve W1 to the pump line 1 or the tank line 2 connected.

In a lifting device, the hydraulic consumer V can Swivel adjustment, e.g. a lifting fork, after both Directions can be provided while the hydro consumer V1 used for another function of the lifting device is.

The bidirectional lowering brake valve Z has a (in the present Case fixed) orifice 9 and a Pressure compensator control orifice arrangement 10, which has a Pilot line 11 with that in the working pressure line 3 prevailing between the chamber 7 and the orifice 9 Pressure and in the opposite direction via a pilot line 12 with the between the orifice 9 and the pressure compensator orifice arrangement 10 prevailing Pressure can be applied. A rule spring 13 (or two) is used to center the pressure compensator orifice plate arrangement 10 in an open normal position.

2 shows the construction of the quantity control device M or the bidirectional lowering brake valve Z shown. It is a screw-in valve, whose screw-in housing G with an external thread section 15 into an internally threaded section 14 of the working pressure line 3 is screwed in. It is conceivable the valve with a conventional block-shaped housing train and connections for the working pressure line 3 to provide.

An axial bore in the housing G forms a housing chamber 16, in which a control piston designed as a hollow pot piston 17 sealed with a guide section 18 is guided. At the open piston end is 19 the measuring aperture 9 in the form of an aperture ring 36 with a Aperture bore 37 set. The one labeled 20 The piston crown contains at least one throttle passage 21 to a control chamber part 22 of the housing chamber 16. Am lower end of the screw-in housing G is a screw-in tool engagement point 23 provided.

In the wall of the control piston 17 are in the circumferential direction distributed radial bores 24 are provided which a pair in Direction of displacement of the control piston 17 spaced first and form second control edges 25, 26. In the wall the housing chamber 16 is an open to the control piston 17 Circumferential groove 27 formed, the groove flanks also a Form a pair of first and second control edges 29, 28. In the circumferential groove 27 open oblique bores 30 which for outer circumference adjacent to the external thread section 15 of the screw-in housing G.

A control spring 13 surrounds the control piston end 19 and is via abutment parts 35 between stops 33 and 34 on Control piston 17 and between abutments 32 and 31 of the Screw-in housing fixed with preload. The abutment 32 is formed by a screw-in ring 40, with which the control piston 17 and the control spring 13 in the screw-in housing G are secured. The stop 33 will formed by a union nut 38 with which the orifice plate 9 against another orifice with different large orifice bore 37 set interchangeably is. The union nut 38 has a passage 39 which is also shaped as a turning aid.

In the position of Fig. 2, pressure medium in the working pressure line 3 happen in each flow direction, as long as the amount of pressure medium is only a pressure difference generated via the orifice 9, which is smaller than the force of the control spring 13 is. In this position the speed of the hydraulic consumer V in FIG. 1 increased or decreased by means of the speed of the pump P. The direction of movement is with the directional valve W set.

The control spring 13 serves to adhere to that shown in FIG. 2 Normal position of the control piston 17. The over the Measuring orifice occurring pressure difference affects that of Guide section 18 defined loading area of the control piston 17, which in Fig. 2 above the orifice 9 acting pressure down while the pressure below the orifice 9 above the Passage 21 in the control chamber part 22 in the direction of displacement acts upwards.

The piston rod of the hydraulic cylinder 5 in FIG. 1 pushed out (Fig. 3, flow direction 41), then acted upon the higher pressure upstream of the orifice 9 den Control piston 17 down while the lower pressure downstream of the orifice 9 via the passage 21 in the control chamber part 22 acts on the control piston 17 upwards. The control spring also acts with the pressure in the control chamber part 22 13 the higher pressure upstream of the orifice 9 opposite. The control piston 17 is (Fig. 3) down postponed. The control edges 25 and 29 cooperate crosswise and regulate the continuous amount of pressure medium a predetermined pressure difference across the orifice 9 adhere to and the speed of the adjustment of the Hydraulic cylinder 5 to keep constant. If the Pressure upstream of the orifice, then the control piston 17 further down and the between the Control edges 25 and 29 continuous quantity further regulated, until the pressure difference across the orifice 9 again is at its predetermined value. The speed of the hydraulic cylinder 5 still does not change. At This control game of the control piston 17 releases the stop 34 of the control piston 17 from the lower on the spring abutment 31 supported spring end of the control spring 13 while the upper stop 33 compresses the control spring, whose upper spring end detaches from the spring abutment 32.

The directional control valve W is changed to the direction of movement of the hydro consumer V, then that will Lowering brake valve Z in the opposite flow direction 42 flows through. The higher pressure then upstream the orifice 9 acts through the passage 21 in the control chamber part 22 on the pressure surface of the control piston 17, while the lower pressure downstream of the Measuring aperture 9 in the opposite direction to the Control piston 17 acts. The control piston 17 is shown in FIG. 4 adjusted upwards. The cross-cooperating control edges 26, 28 regulate the amount of pressure medium so far until the pressure difference across the orifice 9 again corresponds to predetermined value, the movement speed of the hydraulic consumer V in the new adjustment direction is limited. With a pressure increase upstream of the orifice 9, the passage between the Control edges 26, 28 further narrowed, so that the pressure difference is maintained via the orifice 9 and the speed of the hydro consumer does not rise. Takes on the other hand, the pressure downstream of the orifice 9 increases, for example because the load on the hydro consumer V increases, then the control piston 17 in Fig. 4 downwards, so that the control edges 26, 28 move apart and allow a larger amount of pressure medium to pass through Pressure difference across the orifice 9 and the speed of the hydro consumer. In this rule game the control piston 17 (Fig. 4) becomes the control spring 13 between the spring abutment 32 and the stop 34 squeezed as they stop from stop 33 and Spring bearing 31 is released.

It is possible instead of one for both flow directions 41, 42 common control spring 13 two separate Allow control springs 13 to engage the control piston 17. These can be biased differently or differently Have spring stiffness to different Control behavior for the two to be monitored To cause flow directions. Both at one common control spring 13 and two separate Structural measures can be taken to control springs to be able to change the preload as desired. The Installation position of the bidirectional lowering brake valve Z in relation on the hydro consumer doesn't matter. The Orifice plate 9 could also be arranged separately from control piston 17 be.

Claims (15)

1. Volume-regulating device (S) for high-pressure hydraulics, by means of which device, in a hydraulic circuit, the flow of pressure medium to and from a hydraulic consumer (V) of at least one hydraulic consumer (V, V₁) which can be connected to a pressure source (P) can be limited independently of changes in pressure and/or load, having an orifice plate (9), which is assigned a pressure balance regulating restrictor (25-29), which sets the pressure difference predetermined by the orifice plate (9), for each direction of flow, and having at least one line (1, 2) which branches off from the hydraulic circuit, characterized in that the orifice plate (9), structurally combined with the two pressure balance regulating restrictors (25-29) in a two-directional load-lowering brake valve (Z) with exclusively two-way flow regulating function for each direction of flow (41, 42), is arranged in a section of a working pressure line (3), and in that the line (1, 2) which branches off is provided on that side of the two-directional load-lowering brake valve (Z) which is remote from the hydraulic consumer (V).
2. Volume-regulating device according to Claim 1, characterized in that at least one further hydraulic consumer (V₁) and/or a safety pressure-limiting valve (3) is/are connected to the line (1, 2) which branches off.
3. Volume-regulating device according to Claims 1 and 2, characterized in that the hydraulic consumer (V) which is monitored using the two-directional load-lowering brake valve (Z) is subsidiary to the hydraulic consumer (V₁) which is connected to the line which branches off.
4. Volume-regulating device according to at least one of Claims 1 to 3, characterized in that the working pressure lines (3, 4) are connected to a speed-regulated pump (P), the delivery volume of which is proportional to the rotational speed of the pump.
5. Volume-regulating device according to at least one of Claims 1 to 4, characterized in that a directional control valve (W) for setting the direction of movement of the hydraulic consumer (V) is arranged between the pump (P) and the two-directional load-lowering brake valve (Z).
6. Volume-regulating device according to at least one of Claims 1 to 5, characterized in that the hydraulic consumer (V) is a double-acting hydraulic cylinder (5) which has a piston-side and a piston-rod-side working chamber (6, 7), in that the two chambers (6, 7) can be optionally connected to a pump line (1) and a tank line (2) via working pressure lines (3, 4) and the directional control valve (W), which is preferably a 4/3-way control valve with a blocked neutral position, and in that the two-directional load-lowering brake valve (Z) is arranged in that working pressure line (3) which leads from the piston-rod-side chamber (7) to the directional control valve (W).
7. Load-lowering brake valve (Z) for limiting the maximum speed of movement of a hydraulic consumer (V) independently of load or pressure fluctuations, having an orifice plate (9) and a pressure balance regulating restrictor (25-29) which sets the pressure difference across the orifice plate (9), which form a two-way flow regulator for one direction of flow in a working pressure line of the hydraulic consumer, characterized in that the orifice plate (9), together with a second pressure balance regulating restrictor (25, 26, 28, 29) for the other direction of flow, forms a second two-way flow regulator in the same working pressure line (3), and in that the two two-way flow regulators are combined to form a two-directional load-lowering brake valve (Z) and alternately limit the speeds of movement of the hydraulic consumer (V5) in the two directions of movement.
8. Load-lowering brake valve according to Claim 7, characterized in that a hollow regulating piston (17) is sealed in a housing chamber (16), onto one side of which medium can flow via the orifice plate (9), and is guided so that it can be displaced in each direction of flow (41, 42) counter to the force of a regulating spring (13), in that the regulating piston (17) in the housing chamber (16) has an application surface to which, in one displacement direction of the regulating piston (17), the pressure on one side of the orifice plate (9) can be applied and, in the other displacement direction, the pressure on the other side of the orifice plate (9) can be applied, and in that flow passages (24) in the regulating piston (17) and in the wall of the housing chamber (16) form two pairs of first and second control edges (25, 26, 28, 29), which are spaced apart in the direction of displacement of the regulating piston (17) and either the first or the second of which alternately and in a crosswise manner cooperate, as control plate, as a function of the direction of flow.
9. Load-lowering brake valve according to Claim 8, characterized in that the regulating piston (17) is designed as a type piston with an external guide section (18), in that the type piston has, in its base (20), a passage (21) to a control chamber part (22) of the housing chamber (16) and, in its end (19) which is remote from the base (20), has the orifice plate (9), preferably as an exchangeable orifice ring (36).
10. Load-lowering brake valve according to Claim 8, characterized in that a common regulating spring (13) is provided for both directions of displacement of the regulating piston (17), which spring is stressed with a, preferably adjustable, prestress between axially spaced-apart stops (33, 34) of the regulating piston (17) and axially spaced-apart abutments (31, 32) of the housing chamber (16) in such a manner that, depending on the direction of displacement of the regulating piston (17), one end of the spring which lifts off one abutment is supported against the stop and the other end of the spring which lifts off the other stop is supported against the other abutment.
11. Load-lowering brake valve according to Claim 11, characterized in that sleeve-like spring abutment parts (35) are provided in both ends of the spring.
12. Load-lowering brake valve according to Claims 9 to 11, characterized in that the orifice plate (9) is exchangeably fixed to the open piston end (19) by means of a standard union nut (38) which at the same time forms one stop (33) for the regulating spring (13).
13. Load-lowering brake valve according to Claims 8 and 9, characterized in that a dedicated, prestressed regulating spring is provided for each direction of displacement of the regulating piston (17), and in that, preferably, the prestressing or stiffness of one regulating spring can be altered independently of the prestressing or stiffness of the other regulating spring.
14. Load-lowering brake valve according to Claim 8, characterized in that the flow passages (24) in the regulating piston (17) are circumferentially distributed radial bores, and in that the flow passages provided in the wall of the housing chamber, for example in the form of inclined bores (30), open out into a circumferential groove (29) which is open towards the regulating piston (17) and the groove flanks of which form a pair of control edges comprising first and second control edge (29, 28).
15. Load-lowering brake valve according to at least one of Claims 7 to 14, characterized in that the housing chamber (16) is provided in a screw-in housing (G) which between the flow passages (30) and a housing part assigned to that end (19) of the piston onto which medium can flow freely has an externally threaded section (15) and an axially accessible rotary handle (23).

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