EP0877169B1 - Hydraulic control device for the load-independent control of a double acting actuator - Google Patents

Description

State of the art

The invention is based on a hydraulic Control device for load pressure independent control of a double-acting engine according to the in the preamble of Claim 1 specified genus.

Such a hydraulic control device is already used load pressure compensated control of a double acting Motors known from DE 36 34 728 C2, two of which Directional control valves for parallel actuation of the assigned Motors from a common variable displacement pump with pressure medium are supplied, the controller with a control line a shuttle valve chain with the maximum load pressure of the two motors is applied. Here is with everyone Directional control valve the pressure compensator used for load pressure compensation downstream of a metering orifice on the control slide, the Pressure compensator also used for direction control Piston sections of the control spool is connected upstream. The Throttle valve in the downstream pressure compensator is in Opening direction from the pressure downstream of the orifice plate and in Closing direction of the highest load pressure and the Control pressure difference applied by the control spring. With this arrangement can be a so-called Achieve oil flow sharing like many Use cases is required. Flows in here Parallel actuation of two or more directional valves and not sufficient pump oil flow, i.e. in the event of an undersupply, less oil evenly over all orifices. The Pressure differences at the respective orifices are shown smaller and less oil flows to the engines. The oil flow through the directional valves increases in relation to the predetermined target values. So it is principally around a valve arrangement for dividing the pump flow into individual partial flows flowing to each motor, whereby also with different loads on the motors Division ratio remains constant and thus the movements be maintained without the plant coming to a standstill highly loaded engine comes. Despite the beneficial This hydraulic control device has oil flow distribution but the disadvantage of lack of security. So you can Load pressure is not sufficiently safe when the pump pressure drops if the pressure in the control circuit persists, for example Leakage or line break drops. He can also Throttle slide in the pressure compensator one Check valve function not fast enough perceive since it is via control circuits with shuttle valve chains is controlled. Furthermore, the directional valve has no second, Individual orifice on to the oil flow to the engine limit regardless of the slide deflection. Of Another disadvantage is that the directional valve is not a fourth Has switching position for an open gear. Furthermore it is unfavorable that for the formation of the control circuit in Arranged inside the control slide connecting lines need to be relieved to the tank. This leads to a complex, expensive construction of the Control slide.

Furthermore, from DE 40 26 720 A1 is a hydraulic Control device for load pressure independent control of a known double-acting engine, in which a pressure compensator upstream of that formed on the spool Orifice plate is switched. This directional valve can be used with a check valve separated from the pressure compensator Meet security requirements, with discharge of a cross channel between the check valve and orifice plate controlled via a piston section of the control slide which is also designed as a full slide valve. Also points the directional control valve has a second individual orifice Limit the oil flow to. With this directional valve with the Orifice plate upstream pressure compensator is Throttle slide in the closing direction from the pressure upstream of the Orifice plate on the control slide and in the opening direction from Pressure downstream of the orifice plate, i.e. plus the load pressure acted upon by the force of a spring. The pressure compensator holds thus the pressure difference across the measuring throttle on the directional valve constant even with different load pressure, so that too the associated flow rate remains constant and the am Directional control valve set working speed is kept constant. A disadvantage of this Control device is that it is not a supply dependent Allows oil flow sharing. Be with such Directional control valves for several motors in parallel operation is controlled, the motor with the lowest is first Load pressure supplied with a pressure medium stream during the remaining rest of the volume flow to the other motors is directed. This changes the ratio of Distribution of volume flows, which is not constant here remains. In the case of undersupply, this can lead to that the function of the least loaded engine is preserved, while the heavily loaded, parallel actuated engine stops, which in many Use cases is not desirable.

Advantages of the invention

The hydraulic control device according to the invention load-independent control of a double-acting Motors with the characterizing features of claim 1 on the other hand the advantage that they are at a supply-dependent oil flow distribution an increased degree Offers security and an extended usability. So can be separated by the arrangement of the pressure compensator of the check valve in connection with the control of the Pressure relief in the cross channel directly above the Control spool achieve that the load pressure with falling Pump pressure can be kept safer and faster. This also applies if the pressure in the control circuit Leakage or line break decreases. The lines be formed as simply as possible in the control circuit, whereby Connecting lines in the control slide itself are omitted, see above that this as a simple, inexpensive building Full slide can be executed. Furthermore, can this design, the directional valve with a fourth Equip switching position for an open gear, the with the load pressure line connected to the pump is relieved. Further can be a second individual orifice with this directional control valve integrate which the oil flow to the engine limited regardless of the deflection of the control spool. Overall, the control device enables a relative simple and compact design. More beneficial Refinements result from the dependent claims, the Description as well as the drawing.

drawing

An embodiment of the invention is in the drawing shown and in the description below explained. 1 shows a longitudinal section through a hydraulic control device with a directional valve and Combined pressure compensator in a simplified representation, figure 2 as a detail a shuttle valve from a control circuit according to II-II in Figure 1, and Figure 3 is a schematic Representation of a control block for two double-acting Motors with two control devices according to FIG. 1.

Description of the embodiments

Figure 1 shows a longitudinal section through a hydraulic Control device 10 for load pressure-independent control of a double-acting engine. In the control device 10 are the actual directional control valve 11 in the load-sensing version and the associated pressure compensator 12 in one common housing 13 arranged.

The housing 13 has one between the two end faces continuous longitudinal bore 14, in the by annular Extensions trained a total of seven chambers 15 to 21 of which the five adjacent chambers 15 to 19 serve to control the direction of the pressure medium flow, while the two outer chambers 20, 21 one Measuring aperture 22 are assigned, which of Speed control of the engine is used. Of the five adjacent chambers 15 to 19 serve the middle one Chamber as inlet chamber 17, while those lying next to it two chambers a first motor chamber 16 and a second Form motor chamber 18, which with a motor connection 23 or 24 are connected. In addition to each motor chamber 16, 18 there is a return chamber 15 and 19, respectively, which are not shown in FIG drawn way with a return port in the housing 13 are connected. Of the two orifice chambers 20, 21 serves the first lying next to the second return chamber 19 Orifice chamber 20 as a discharge orifice chamber and the other as the inlet-side, second orifice chamber 21.

In the longitudinal bore 14, a spool 25 is tight and slidably guided. The control slide 25 is by annular grooves divided into six piston sections 27 to 32. The three adjacent piston sections 27, 28, 29 are with Control edges equipped and serve the direction control. An adjoining fourth piston section 30, which in the drawn neutral position of the spool 25 in the outlet-side measuring orifice chamber 20 is used all to relieve a control circuit. The one about it subsequent fifth piston section 31 is part of the Measuring aperture 22 and determines with its control edges Deflection of the control spool in both working positions the size of the volume flow to the motor and thus its speed. The outer, sixth piston section 32 protrudes from the longitudinal bore 14 so that a attack actuator not shown can. The protrudes at its opposite end Control slide 25 with the first piston section 27 in one double-acting return device 33, the type of which is known per se and which the spool in its Neutral position 34 centered, out of which he in two Working positions 35 and 36 can be deflected. Furthermore, the Control slide 25 to a fourth switching position 37, which as Free position is executed.

As FIG. 1 also shows, is in the housing 13 below the longitudinal bore 14 a second bore 39 and below a third bore 41 is arranged, all parallel to the Longitudinal bore 14 run. The second bore 39 is trained like a blind hole and takes up inside Check valve 42 with its spherical closing member 43 on. In contrast, there is the third, multiple offset Bore 41 between the two end faces of the housing 13 and in addition to the pressure compensator 12 also takes a second individual orifice plate 44 on. To make this possible, the discharge-side orifice chamber 20 a perpendicular to Spool 25 extending extension 45, which intersects the third bore 41. Besides this Extension 45 also extends in the housing 13 perpendicular to the longitudinal slide 25 a circulation chamber 46, in whose end near the slide opens into the second bore 39, while with its end facing away from the longitudinal slide 25 penetrates the third bore 41. That way it forms one between the extension 45 and the circulation chamber 46 extending wall of the housing 13 an annular web 47, the both as a control edge for the second orifice 44, and serves for a throttle slide 48 of the pressure compensator 12. The Throttle slide 48 is a hollow slide with a Blind bore 49 and a radial bore 51 executed, see above that he is in the starting position centered by the control spring 52 the circulation chamber 46 with the discharge-side orifice chamber 20 connects in a throttled manner. If the throttle valve 48 occupies his working position in the company Connection controlled via the radial bore 51. The Throttle valve 48 is on its right front side Pressure in the extension 45 in the opening direction, that is acted against the force of the spring 52. In The closing direction acts on the throttle slide 48 the control spring 52 and the maximum load pressure in the spring chamber 53, via a control opening 54 from a control circuit is fed.

As FIG. 1 also shows, lies in the second hole 39 in the area between the securing the inlet chamber 17 Check valve 42 and the circulation chamber 46 a Pressure tap opening 55, through which the maximum load pressure of the connected motor is tapped. Like the figure 2 shows as a detail, this pressure signal from the Pressure tap opening 55 in the directional control valve 11 in one Shuttle valve 56 with a different pressure signal from one second directional control valve 70 compared and the selected maximum load pressure signal via a control channel 57 forwarded. Form shuttle valve 56 and control channel 57 thereby parts of a known control circuit 58 in which in a manner known per se via shuttle valve chains maximum load pressure selected and for a load sensing control is used.

While the inlet-side orifice chamber 21 with a Inlet channel 61 is connected, the two flange surfaces of the housing 13 connects to each other discharge-side orifice chamber 20 via a transverse channel 62 with the inlet chamber 17 in connection, in which Cross channel 62 one behind the other, the individual orifice 44, the Pressure compensator 12 and the separate check valve 42 are switched. The throttle slide 48 is thus downstream of the orifice 22 and is such of Tax pressures that with him a supply-dependent oil flow distribution is achieved.

Figure 3 shows a schematic representation of a Control block in which, in addition to the first control device 10 a similar, second control device 70 are flanged together so that at least two double-acting motors can be operated in parallel. The Control devices 10, 70 are between one Connection plate 71 and an end plate 73 switched and connected in parallel to the continuous inlet channel 61. The inlet channel 61 is from a pressure medium supply unit 73 supplied with pressure medium, with the Control circuit 58 of the maximum load pressure is returned. For this purpose, the shuttle valves 56 form in both Control devices 10, 70 a valve chain, via which the maximum load pressure is selected or one Relief of the control circuit 58 is made.

The operation of the control device 10 is as follows explained, the basic function of such Load-sensing valves are assumed to be known per se. With the same, connected in parallel Control devices 10, 70 is the pressure compensator 12 Measuring aperture 20 is connected downstream and is also upstream from the directional control edges in the directional control valve 11. The LS pressure tap, that is, the one that taps the load pressure Pressure tap opening 55 in the directional control valve 11 lies between the Pressure compensator 12 and the check valve 42, so that the respective pressure signal via the shuttle valve 56 in the Control circuit 58 is given. The one in the control circuit 58 The selected, highest load pressure becomes pump 73 on the one hand and on the other hand into the spring chambers 53 of the pressure compensators 12 passed, this load pressure signal via control lines and the control openings 54 enter the spring chambers 53. On the opposite end is the throttle slide 48 from the pressure downstream of the orifice 22 in the opening direction applied. This type of interconnection and the Pressurization of the throttle slide 48 enables one supply-dependent oil flow distribution at Parallel actuation of both control devices 10, 70.

In the neutral position 34, as shown in FIG. 1 and FIG. 3 is shown in more detail, is that at the pressure tap opening 55 hanging control circuit 58 via the circulation chamber 46, the controlled radial bore 51 and the blind bore 59 in Throttle slide 48, the extension 45, the outlet side Orifice chamber 20 and the open control edge on the fourth Piston section 30 to the second return chamber 19 is relieved. This also lowers the pump 73 Output pressure regulated. This relieves the LS pressure line builds on the pressure compensator 12 and the spool 25 particularly simple and enables training of Control spool 25 as a full spool, which is therefore no internal connection holes. The same kind of Relief can also be achieved if the control spool 25 occupies its fourth switching position 37 for clearance.

If the control device 10 is operated by itself and deflected into one of the working positions 35 or 36, so a load pressure independent control of the connected motor. The one from the Pressure medium supply unit 73 via the inlet channel 61 incoming volume flow flows via the controlled Orifice plate 22 and the downstream pressure compensator 12 and that Check valve 42 in the inlet chamber 17 and on to Motor or from the motor back into the return. Before doing this the throttle slide 48 in the pressure compensator 12 opens, controls he the relief connection via the radial bore 51. The control edge also closes at the fourth piston section 30 the connection to the return chamber 19 before the orifice 22 opens. In this way there is no loss of oil to the return on. The pressure compensator 12 maintains the pressure drop the measuring aperture 22 constant in a manner known per se, so that the speed of the motor proportional to the displacement of the spool 25 and regardless of Load pressure fluctuations is controlled. Should do this Leakage or a sticking shuttle valve the function of the Pressure compensator 12 may be impaired, in any case close the check valve 42 and prevent oil from the load flows towards the pump connection. Independent of the pressure conditions in the spring chamber 53 of the pressure compensator 12 a load on the motor becomes safe when the pump pressure drops held. The check valve 42 designed as a seat valve ensures low leakage.

If both control devices 10, 70 are operated in parallel, this results in a supply-dependent oil flow distribution, which is also referred to as so-called social behavior.

The highest is on one of the motors occurring load pressure to all pressure compensators 12 the Control devices 10 and 70 created. With that, pose the throttle slide 48 of both pressure compensators 12 so that at their end faces facing the respective measuring aperture 22 always with different loads on the motors the same pressure prevails, so that the orifice 22 from im Relative to each other constant amounts of pressure medium be flowed through. In principle, it is about a valve arrangement for dividing the pump flow into individual partial flows flowing to each motor, whereby also with different loads on the motors Division ratio remains constant and thus the desired Speed is maintained. Flows at this Parallel actuation of both control devices 10, 70 none sufficient pump oil flow so that an undersupply is present, then flows evenly over all orifices 22 correspondingly less oil. This is ensured by the downstream Pressure compensator 12, which always keeps the pressure at the highest Load pressure plus regulating pressure difference regulates. The Pressure differences at the orifice plates 22 become smaller and less oil flows to the engines. The oil flow through the directional valves 11 increases in relation to the given Setpoints.

The directional valve 11 also has a fourth Switch position, this free position 37 by Pressing the control slide 25 into the housing 13 is achieved. Both are in this release position Motor connections 23, 24 with the return chambers 15 and 19 connected and the LS pressure line is relieved.

With the second individual orifice 44, which between the Orifice plate 22 on control slide 25 and pressure compensator 12 is switched, the volume flow can be independent of Limit the stroke of the control slide 25 for the directional valve 11, as is known in itself.

The formation of the control device 10 with one of the Measuring orifice 22 connected downstream on the control slide 25 Pressure compensator 12, with the one separated from the pressure compensator 12 Check valve 42 and with the relief of the LS pressure line 55 via the throttle valve 48 and the Control spool 25 for returning, the control spool 25 is designed as a full slide valve particularly advantageous combination.

Of course, are shown on the embodiment Changes within the scope of the protection request are possible.

Claims (12)

1. Hydraulic control device for the load-pressure-independent control of a double-acting engine, with a directional valve (10), the housing (13) of which receives in a longitudinal bore (14) a control slide (25) which has piston portions which serve for controlling the speed and direction of the engine and of which the piston portion serving as a measuring diaphragm (22) for the speed control, on the control slide, is connected via a housing-side transverse duct (62) to the piston portions (27-29), arranged separately from the said piston portion, for direction control, on the control slide (25), this transverse duct (62) having inserted in it a two-way pressure balance (12) which controls the volume flow and the throttle slide (48) of which is acted upon in the closing direction by a spring (52) and a maximum load pressure and in the opening direction by the pressure in the transverse duct (62), downstream of the measuring diaphragm (22) and upstream of the pressure balance (12), and with a pressure pick-up orifice (55) for a control circuit, the said pressure pick-up orifice lying downstream of the throttle slide (48), in the transverse duct (62), and being capable of being relieved to a return chamber (19) via a relief device on the control slide, characterized in that a non-return valve (42) separate from the throttle slide (48) is inserted into the transverse duct (62), downstream of the pressure balance (12) and upstream of the control slide (25), in that the pressure pick-up orifice (55) lies upstream of the non-return valve (42), in that the relief device has, on the control slide (25) , a piston portion (30) which controls the connection between an outflow-side measuring-diaphragm chamber (20) and the adjacent return chamber (19), and in that the throttle slide (48), in its initial position (74), makes a throttled connection (51, 49) between the pressure pick-up orifice (55) and this measuring-diaphragm chamber (20) and, in its working positions (75), shuts off this connection (51, 49).
2. Hydraulic control device according to Claim 1, characterized in that a second individual measuring diaphragm (44), which, in particular, is designed to be adjustable, is inserted into the transverse duct (62), downstream of the measuring diaphragm (22) and upstream of the pressure balance (20).
3. Hydraulic control device according to Claim 1 or 2, characterized in that the control slide (25) has, in additon to a neutral position (34) and two working positions (35, 36), a fourth switching position (37) for free motion.
4. Hydraulic control device according to one of Claims 1 to 3, characterized in that the control slide (25) is designed as a solid slide without connecting lines for working or control-pressure media inside it.
5. Hydraulic control device according to one of Claims 2 to 4, characterized in that the housing (13) has two bores (39, 41) which run parallel to the longitudinal bore (14) for the control slide (25) and which all lie in one plane and of which the second, middle bore (39) receives the non-return valve (42), whilst the pressure balance (12) and the individual measuring diaphragm (44) are arranged in the other, third bore (41).
6. Hydraulic control device according to Claim 5, characterized in that the middle bore (39) is designed in a manner of a blind hole and projects with its inner end into a circulation chamber (46) which runs perpendicularly to the longitudinal axis of the control slide (25) and which passes through the third bore (41).
7. Hydraulic control device according to Claim 6, characterized in that the measuring-diaphragm chamber (20) lying downstream has a prolongation (45) which extends perpendicularly to the control slide (25) and which runs essentially parallel to the circulation chamber (46) and passes through the third bore (41), whilst the measuring-diaphragm chamber (21) lying upstream is connected to an inflow duct (61).
8. Hydraulic control device according to one of Claims 1 to 7, characterized in that the measuring-diaphragm chambers (20, 21) assigned to the measuring diaphragm (22) are arranged in the longitudinal bore (14) laterally next to the five working chambers (15 to 19) for direction control in the housing (13).
9. Hydraulic control device according to one of Claims 1 to 8, characterized in that the throttle slide (48) is designed as a hollow slide with a blind-hole bore (49) and, for controlling the relief of the pressure pick-up orifice (55), has a radial bore (51) capable of being overlapped as a function of position.
10. Hydraulic control device according to one of Claims 6 to 9, characterized in that the wall lying in the housing (13) between the circulation chamber (46) and the outflow-side measuring-diaphragm chamber (20), in the third bore (41), forms an annular web (47) which forms the housing-side control edges for the throttle slide (48) and for the individual measuring diaphragm (44).
11. Hydraulic control device according to Claim 10, characterized in that the annular web (47) lies approximately the same radial plane as the relief-controlling piston portion (30) on the control slide (25) in its neutral position (34).
12. Hydraulic control device according to one of Claims 1 to 11, characterized in that the throttle slide (48) has, between its initial position (74) and its working positions (75), a shut-off position (76), in which the throttled connection (51) is closed and the transverse duct (62) is not yet opened.

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