EP2466152A1 - Electrohydraulic control device - Google Patents

Abstract

The device (EHR) has a lifting section (37) and a lowering section (38) with proportional-pressure regulating valves (41, 50) with leakage-free locking position for load pressure, a load pressure signal circuit (LS), and an electric control device. The electric control device is connected with proportional magnets (2, 2') and sensors (49, 51, 52), which notifies actual states. The proportional-pressure regulating valves arranged at the lifting section are formed with a pressure control (43) and actuated by the proportional magnets in a load-pressure compensating manner.

Description

The invention relates to an electro-hydraulic control device specified in the preamble of claim 1. Art.

Such mobile working machines include, without limitation, for example, tugboats with attachment equipment, agricultural machinery such as tugs, graders, wheel loaders, road maintenance vehicles, seeders, and similar work machines. The proposed in such mobile machines electro-hydraulic control devices show in practice, despite high control effort no properly load-independent performance. Known from the prospectus of the company Bosch "EHR system, EHR 23 LS Bosch, the control device has in the lifting strand of the unilaterally acted on a hydraulic motor directly actuated by a proportional solenoid 2/3-Druckregelsitzventil on which an inlet pressure compensator is connected upstream The proportional solenoid does not receive any feedback on the actual load pressure or load pressure changes as soon as the pressure regulator seat valve is opened by energizing the proportional solenoid The inlet pressure compensator is an additional required equipment component of the control device and increases the throttle loss in the lifting control.

In the prospectus of Rexroth Bosch Group, 1 987 760 507 / 09.99; AKY 005/7 "Electro-Hydraulic Hoist Control" for high performance tractors or tractors, page 4/55, is also an electrohydraulic control device DE 10 200 033 315 A known, in which the controllable via the electronic control unit control valve for a front or rear-factory controls the admission of the respective hydraulic motor or regulates. According to DE 10 2004 033 315 A the pressure regulating seat valves arranged in the lift train and lowering train are proportionally actuated via their pressure pilot controls proportionally via an upstream 4/4-proportional directional spool valve with two proportional solenoids. Although a load pressure signal circuit is provided, there is nevertheless no sufficient precision of the load pressure independence, although the 4/4-proportional directional spool is preceded by an inlet pressure compensator. This control device is complex and complex and requires considerable throttle losses, since there are several throttling stages between the pressure source and the hydraulic motor.

Even with the out EP 2 031 256 A known, complex electro-hydraulic control device is the two proportional pressure control seat valves upstream of a 4/4-proportional directional spool with inlet regulator.

The invention has for its object to provide an electro-hydraulic control device of the type mentioned, the structurally simple and low-loss operation allows control or regulation of the hydraulic motor of the hoist, which is characterized by complete load pressure independence.

The stated object is achieved with the features of claim 1.

Since at least disposed in the lifting strand proportional pressure regulating seat valve is designed with pressure precontrol and having a proportional solenoid which actuates the pressure precontrol load pressure compensating, the control device operates at least when lifting or in a lifting control completely independent of load pressure. Such pressure-independent proportional pressure control seat valves with pressure precontrol are in the European patent application with the file number 09 008 683.6-1252 proposed by the Applicant, the entire disclosure of which is hereby incorporated by reference. The control device is structurally simple, since in addition to the proportional pressure control seat valves for lifting and lowering control no further valve components are needed, whereby the throttle losses are minimized at least in the lifting control.

In an expedient embodiment, with regard to a completely load pressure-independent lowering control or lowering control, the proportional pressure regulating seat valve in the drain train is also provided with a pressure precontrol which actuates a proportional solenoid in a load pressure compensating manner so that a completely load pressure independent control is possible.

In an expedient embodiment, at least the lifting strand is connected upstream of the proportional Druckregelsitzventils to a hydropneumatic gas pressure accumulator, for example, to produce a certain damping and / or suspension and / or to operate the control device with energy recovery and / or less Einschaltzyklen the pressure source.

Since functions are usually required in a hoist in which a limitation of the force generated by the hoist is required at least in the lifting control, in an expedient embodiment, at least the lifting strand via a secondary pressure relief valve or a changeover valve with a tank connected. The secondary pressure relief valve responds to a set maximum pressure and limits this. The change-over valve allows an optional pressure limiting function or pressure relief function for the hoist.

The secondary pressure relief valve is adjusted by a proportional solenoid in an expedient embodiment, so that the maximum pressure is sensitive and can be changed even during operation, especially for certain functions can be set to a very low pressure value.

In one embodiment with a switching valve this is expediently a magnetic switching valve, which is connected via the electrical or electronic control unit as needed or for certain functions.

The magnetic switching valve is expediently a 2/2-way valve which blocks the lifting strand against the tank in a switching position and keeps the load pressure signal circuit open, which is then used for example to control the pressure supply from a pressure source in operation the other switching position relieves the hoist line and the load pressure signal circuit to the tank to limit or reduce the maximum force for the hydraulic motor of the hoist or reduce and at the same time relieve the load pressure signal circuit, which is useful, for example, when transporting the machine, so the pressure source, a variable displacement pump or a fixed displacement pump, does not respond to load pressure signal shocks resulting from travel or the like, and could cause the hoist to oscillate with the implement attached thereto.

In the case of a hydraulic motor which can be acted upon on one side, it is expedient to connect the load-pressure signal circuit, preferably via a shuttle valve, only to the lifting cable. In the case of a double-sided acted hydraulic motor, however, the load pressure signal circuit via a further shuttle valve downstream of the respective proportional pressure regulating seat valve and pressure-dependent connected to the hoisting line or the sink train.

In an expedient embodiment, a control force acting on at least one armature of the proportional magnet is generated hydraulically in the pressure precontrol of the proportional pressure regulating seat valve from the load pressure. Thus, the proportional solenoid can regulate clearer and more responsive than with load pressure signals from the load pressure signal circuit. In this case, preferably, the profile of the varying control force is selected such that at each set value of the current supply of the proportional solenoid, the amount flowing between the load pressure side and the low pressure side is independent of at least changes in the load pressure either constant durable or even user-specific adjustable. User-specific controllable in this context means that in certain applications, no absolute load pressure-independent control is desired, but adjusted to meet user-specific requirements. This may relate, for example, to applications in which the quantity should remain constant only over a partial region of the setting stroke of the proportional magnet, and is to be regulated outside of this subrange according to other requirements. Thus, the force curve can be set linearly or as a curved curve, wherein it is crucial that the control of the amount in each case is independent of the load pressure or changes in the load pressure. Incidentally, the proportional pressure regulating seat valve may be selected so that it is closed either normally open or de-energized.

In an advantageous embodiment, the load pressure independent controllable proportional pressure regulating seat valve has a valve seat between the load pressure side and the low pressure side, a cooperating with the valve seat, a seat having a main piston which is sealed displaceable in a control chamber, one of a pilot seat in the main piston and a pilot cone existing Druckvorsteuerungs pilot valve between the control chamber and the low pressure side, a pilot cone acting on the control spring and an armature pilot valve proportional solenoid which is energized coupled in at least one direction of its Stellhubs to a starting position with the pilot cone, wherein between the load pressure side and the control chamber a Flow connection with a fixed throttle and between the fixed throttle and the control chamber, a control throttle are provided, wherein the size of the actuating throttle with open pilot valve over the setting stroke of the armature is variable, and the control throttle from the load pressure directly or via the pilot cone at the anchor dependent on the pressure difference between the load pressure side and the low pressure side Regulating force generated. Since the varying control force then provides feedback to the proportional magnet with respect to the actual load pressure, the proportional magnet can regulate the respective quantity completely independently of the load pressure via the pressure precontrol. The control choke, the instantaneous size of which depends on the position of the armature, forces the armature open the pilot force, which is a meaningful feedback to the value of the pressure difference between the load pressure side and the low pressure side, so that the proportional solenoid in conjunction with the control spring either complete independent of load or even according to user-specific requirements can regulate load-independent. The control force is an additional control parameter as defined information about the pressure difference between the load pressure side and the low pressure side or to load pressure change in order to be able to regulate the amount ideally independent of the load.

Depending on whether the proportional pressure regulating seat valve shuts off without current or is kept open by the regulating spring, the control force on the armature, which is generated hydraulically, acts either in the closing direction or in the opening direction of the pilot valve, ie opposite to the direction of action of the armature when the proportional solenoid is energized that the proportional solenoid picks up the control force as uniquely identifiable control parameters.

In a further advantageous embodiment, an auxiliary control chamber is provided between the armature and the fixed throttle, one end of the armature receiving control chamber, which is separated from the control chamber by a passage having a partition wall through which the pilot cone extends into the control chamber , To generate the governing force, the pilot cone has a cam portion that gradually increases toward the pilot's seat and relative to an axis of the pilot cone, the locator being defined by the cam portion and the passage. This training is useful for a proportional pressure regulating seat valve that is de-energized in the locked position. Since the control choke gradually narrows in the opening direction as the actuating stroke of the pilot cone increases, a throttling effect with a flow dynamics arises, which hydraulically generates the control force from the load pressure. The armature itself is expedient, for example, based on the pressure in the auxiliary control chamber, pressure balanced, so that the control force is not affected by any distorting forces at the anchor.

In an expedient embodiment, the armature extends into the control chamber, wherein it is sealed with at least one sealing portion in a stationary sealing portion, which limits the control chamber and communicates with the fixed throttle. The control throttle is defined between the sealing sections, so that the control force is generated hydraulically from the load pressure directly at the armature.

In this case, it is expedient for the armature and a guide bore each facing away from the control chamber to have a first sealing section with a larger effective diameter and the control chamber facing a second sealing section with a smaller effective diameter. The first sealing portion of the armature defines a sealed against the control chamber and communicating with the load pressure side annular chamber. The fixed throttle is arranged between the first and second sealing portions, so that it opens into the guide bore. The armature has here in the second sealing portion on a direction sloping toward the control chamber control surface portion, wherein on the side facing the control chamber side of the fixed throttle in the guide bore between the sealing portions a circumferential control edge is provided with the control surface portion of the armature here here blind-shaped control choke Are defined. The blind-like interaction between the control edge and the control surface section at the anchor allows an exact predetermination of the stroke-dependent varying course of the control force.

Fig. 1

eine erste Ausführungsform einer elektrohydraulischen Steuervorrichtung eines Hubwerks einer fahrbaren Arbeitsmaschine, als Blockschaltbild mit zugeordnetem Wirkschema,

Fig. 2

eine weitere Ausführungsform der elektrohydraulischen Steuervorrichtung für das Hubwerk von Fig. 1,

Fig. 3

eine elektrohydraulische Steuervorrichtung in einer anderen Ausführungs-form für ein Hubwerk mit einem doppelt wirkend beaufschlagbaren Hydro-motor,

Fig.4

ein Blockschaltbild einer weiteren Ausführungsform der elektrohydraulischen Steuervorrichtung für das Hubwerk der Fig. 3,

Fig.5

einen Längsschnitt einer ersten Ausführungsform eines Proportional-Druckregelsitzventils, in drucklosem Zustand, und

Fig. 6

eine weitere Ausführungsform eines Proportional-Druckregelsitzventils, in drucklosem Zustand.

Embodiments of the subject invention will be explained with reference to the drawings. Show it:

Fig. 1

a first embodiment of an electro-hydraulic control device of a hoist of a mobile work machine, as a block diagram with an associated operating scheme,

Fig. 2

a further embodiment of the electro-hydraulic control device for the hoist of Fig. 1 .

Fig. 3

an electro-hydraulic control device in another embodiment for a hoist with a double-acting hydro-motor,

Figure 4

a block diagram of another embodiment of the electro-hydraulic control device for the hoist of Fig. 3 .

Figure 5

a longitudinal section of a first embodiment of a proportional pressure control seat valve, in a pressureless state, and

Fig. 6

Another embodiment of a proportional pressure regulating seat valve, in a pressureless state.

A mobile work machine M according to Fig. 1 has a hoist H (at the rear or at the front or on one side), which is controllable and / or regulated by means of at least one unidirectional hydraulic motor Z via an electro-hydraulic control device EHR, by means of an electrical or electronic control unit CU. The control unit CU can be, for example, a CAN arithmetic unit which receives its supply voltage via a line 33, leads at 34 to interfaces, and has outputs 35. The control unit CU is connected to electrical or electronic components in the work machine M and / or the control device EHR, and may comprise an input and display section, not shown.

The hydraulic motor Z is for example a differential cylinder whose piston-side chamber is connected via a working line 36 to an output 44 of the control device EHR.

The control device EHR has a hoist line 37 and a drain line 38 and is connected to a load pressure signal circuit LS and a pressure source P (constant pump or control pump) and a tank R. From the pressure source P, a pressure line 39 leads to the lifting strand 37, while from the connection 44 a drain line 45 leads to a tank line 46. In the lift train 37 and, preferably, in the drain train 38, a proportional pressure regulating seat valve 41 or 50 with a proportional solenoid 2, 2 '(PE1, PE2 indicate the respective energization) and a pressure pilot control 43, for example with a pressure reducing valve actuated by the proportional solenoid , At least the proportional pressure regulating seat valve 41 in the lifting train can be operated independently of the load pressure. Suitably, the proportional pressure control seat valve 50 in the sink train 38 is also completely load-independent operable (load pressure compensated). In the lift train 37, check valves 40 are arranged upstream and downstream of the proportional pressure regulating seat valve 41 and block check valves in the return flow direction. Optionally available to the Stirrup 37 a hydropneumatic gas pressure accumulator 48 may be connected, which is connected via a blocking in the outflow direction check valve 40 'to the terminal 44. The pressure at port 44 is reported via a pressure sensor 49 to the control unit CU. The hoist H may be associated with a displacement sensor 52 and a force sensor 51, which are also connected to the control unit CU, as well as the proportional solenoid 2, 2 'and optionally a not shown drive the pressure source P. The lifting strand 37 and the drainage strand 38 are also connected together to a line 53 which leads to the tank line 46 and in Fig. 1 contains a secondary pressure relief valve 47, the response pressure is appropriately adjustable. The proportional pressure regulating valve 41 is connected so that it blocks against the pressure in the pressure line 39, while the proportional pressure control valve 50 is connected so that it locks against the load pressure in the control line 54. The load pressure signal circuit LS is connected via a shuttle valve 57 to the pressure line 39 downstream of the proportional pressure regulating seat valve 41.

In the Fig. 2 shown, alternative embodiment of the electro-hydraulic control device EHR for the hoist H of Fig. 1 is different from that of Fig. 1 in that instead of the manually adjustable secondary pressure limiting valve 47 in the conduit 53 to the tank R, a remotely adjustable pressure limiting valve 47 'with a proportional magnet 55 is provided (energization indicated by PE3).

In the embodiment in FIG Fig. 1 the secondary pressure relief valve 47 can be set by hand to the respective required set pressure, while the secondary pressure relief valve 47 'in Fig. 2 can be adjusted by the proportional solenoid 55 even during operation, appropriately monitored by the pressure sensor 49, for example via the control unit CU.

Fig. 3 illustrates a mobile machine M with a hoist H with at least one double-acting hydromotor Z, for example, a differential cylinder whose piston-side and piston rod side chambers are connected via two working lines 36 and 56 with the electro-hydraulic control device EHR. In connected via the line 45 to the pressure line 39 drain line 38, the proportional pressure regulating seat valve 50 'is connected here so that it locks against the pressure in the pressure line 39. The load pressure signal circuit LS is connected via a further shuttle valve 58 to both working lines 36, 56. When lowering hydraulic fluid either fed into the optionally existing gas pressure accumulator 48, or returned to the energy saving in the conduit 45 as soon as the proportional pressure regulating seat valve 50 'is controlled by its proportional solenoid 2' (PE2). The secondary pressure relief valve 47 'is here by means of the proportional solenoid 55 (energization PE3) adjustable and connected separately from the sink string 38 directly to the tank line 46.

The embodiment of the electrohydraulic control device EHR in Fig. 4 is different from that of Fig. 3 thereby (likewise for the hoist H of the Fig. 3 with the double-sided acted upon hydraulic motor Z) that the optionally usable gas pressure accumulator 48 is missing here, and instead of the secondary pressure relief valve 47 'is provided a switching valve 49 which is connected in the line 53 to the tank line 46 so that it is not energized the control line 54 for Load pressure signal circuit LS consistently holds and simultaneously shuts off the line 53 to the tank line 46, or energized (PE3) via a black / white magnet 60, both the line 53 and the control line 54 with each other and with the tank line 46 connects.

The Fig. 5 and 6 each show a proportional pressure regulating seat valve 41, 50, 50 ', as for example in the electro-hydraulic control device EHR of Fig. 1 to 4 at least in the hoisting line 37 can be used to allow a precise load-independent volume control sensitive. A screw-in cartridge design E is shown, although alternatively a conventional block design is possible.

In the Fig. 5 shown Einschraubpatrone E is screwed with a proportional solenoid 2, 2 'bearing screw 1 in a stepped bore 6 (with an internal threaded portion) of a block 5, in which intersect channels 7, 8 corresponding to the load pressure side or the low pressure side (eg the lifting strand 37 or drain line 38 and the pressure line 39 in the Fig. 1 to 4 ).

The proportional magnet 2, 2 'has an armature 3, which is moved under current flow relative to a stationary magnet part 4 from the position shown upwards and thereby develops a dependent on the value of the current supply force. The screw-1 is sealed in sealing areas 7, 8 and contains a sealed sleeve body 9, in which a main piston 10 is sealed displaced. The main piston 10 has a sealing surface 11, for example a conical or chamfered sealing surface and, preferably, an approximately cylindrical or slightly conical Mengenregelfortsatz 32, which dips into a valve seat 12 of the sleeve body 9. A bore 13 in the main piston 10 leads to a pilot seat 14 of a predetermined cross-sectional size. A control chamber 15 above the main piston 10 is bounded by a partition wall T of a sleeve 16.

In screw-1 a connection 18 is provided to the load pressure side, which contains a fixed throttle F of a certain cross-sectional size. The cross-sectional size of the fixed throttle F is smaller than the cross-sectional size of the pilot seat 14. The armature 3 dives with its lower end loosely in the sleeve 16 and limited with the partition T an auxiliary control chamber 17, which communicates via a passage 19 with the fixed throttle F. In the sleeve 16, optionally, a further passage 20 between the fixed throttle F and the auxiliary control chamber 17 may be provided.

In an oversized inner bore of the armature 3, a plunger-shaped pilot cone 21 is arranged, the above has a pierced end flange 22 for cooperation with a driver shoulder 22 'in the armature 3, wherein the end flange 22 is acted upon by a control spring 23 down, which abuts the magnetic body 4 is supported. Optionally, a bias adjuster 24, e.g. a sleeve provided, either as shown, between the end flange 22 and the control spring 23 or between the control spring 23 and the magnet body 4. Thus, the armature 3 is pressure balanced with respect to the pressure in the auxiliary control chamber 17.

Between the fixed throttle F and the auxiliary control chamber 17 and the control chamber 15, a control throttle S is provided, the instantaneous size of the relative stroke position of the pilot cone 21 and the armature 3 with respect to the valve seat 12, for example. The control throttle S is defined by a passage 25 in the partition wall T and a control surface portion 26 on the pilot cone 21, which passes through the passage 25 for cooperation with the pilot seat 14. The control surface portion 26 is formed inclined relative to the axis of the pilot cone and toward the pilot seat 14. For example, the cam surface portion 26 is an approximately conical thickening of the round pilot cone 21, wherein the generatrix of the cam portion 26 may be a straight or a convex or concave curve, or straight and / or curved sections.

The farther the pilot cone 21 is moved with the armature 3 at powered Proportionalmagneten over the shut-off position shown, the closer the cross-section of the control throttle S. When the pilot valve and decreasing pressure in the control chamber 15 is from the pressure in the auxiliary control chamber 17, such adjusted from the load pressure on the fixed throttle F, hydraulically generates a varying control force K, which acts on the armature 3 in the closing direction of the pilot valve. The control force K represents a feedback of the load pressure at the load pressure side and is used by the proportional solenoid 2 as a further control parameter with open pilot valve against the force of the control spring 23 to perform an accurate flow control completely independent of the load pressure.

If load pressure is present at the load pressure side, the pilot seat 14 is closed by the pilot cone 21 (control spring 23) in the de-energized state of the proportional solenoid 2, 2 '. The pressure builds up from the load pressure via the fixed throttle F and the wide open throttle S in the control chamber 15 the main piston 10 on the valve seat 12th

If the proportional magnet 2, 2 'energized with a certain current value corresponding to a certain speed of the hydraulic motor Z, then generates the armature 3 against the control spring 23 an upward traction, which lifts the pilot cone 21 from the pilot seat 14, so that the pressure in the control chamber 15 to the low pressure side or the channel 8 drops. The cross section of the control throttle S narrows so that the control force K with a value corresponding to the stroke position of the armature 3 acts against the force of the control spring on the armature 3. Since the load pressure from the channel 7 acts on the main piston 10 on an annular cross-section, which is defined by the outer diameter of the main piston 10 and the diameter of the valve seat 12, the main piston 10 is lifted from the valve seat 12. Hydraulic medium flows from the channel 7 to the channel 8. The main piston 10 approaches the pilot cone 21, so that the pilot seat 14 is throttled or finally closed, and a balance between the control force K, the force of the control spring 23, and the magnetic force of the armature 3, and a pressure difference between the load pressure in the channel 7 and the pressure in the channel 8 is formed, which corresponds to a certain amount and thus the desired speed of the hydraulic motor Z. The value of the pressure difference is kept constant at constant current now, for example by a control independent of at least changes in the load pressure. If the load pressure increases (increasing the pressure difference), then the control force K increases, and the pressure in the control chamber 15 increases, so that the main piston 10 throttles more strongly at the valve seat 12 and in turn keeps the volume constant. If the load pressure in the channel 7 drops, the control force K decreases and the pressure in the control chamber 15 is reduced, so that the main piston 10 at the valve seat 12 throttles less and in turn the amount is kept constant. In this quantity control, the extension 32 acts in the valve seat 12.

If the energization is increased, then the control throttle S further throttles, so that the control force K increases until a new equilibrium is established and for the new current value is independent of the load pressure flow control for now a larger amount or other pressure difference.

Conversely, at a lower energization, the control force K is reduced because the control spring 23, the pilot cone 21 further pushes down until an equilibrium sets again and the amount is kept constant, taking into account the control force K. The control force K is here generated hydraulically on the pilot cone 21 and transmitted to the armature 3 via the end flange 22 and the driver shoulder 22 '.

In the Fig. 6 shown embodiment of the proportional pressure regulating seat valve 2, 2 '(normally shut off) differs from that of Fig. 5 characterized in that the control force K is generated directly at the armature 3, for which the control throttle S between the armature 3 and the sleeve 16 'is arranged and defined so that the cross section of the control throttle S only from the stroke position of the armature 3 at current-fed proportional solenoid 2, 2 'depends.

The fixed throttle F opens into Fig. 6 in the sleeve 16 'on a shoulder 29 between an overhead first sealing portion 26 having a larger effective diameter and a lower second sealing portion 27 with a smaller effective diameter. In the sleeve 16 'inside a control edge 31 is provided. A lateral passage 20 in the sleeve 16 'connects, bypassing the fixed throttle F, the channel 7 with an annular chamber 25 which is delimited by an overhead section of the armature 3, the screw-in body 1 and the upper first sealing section 26 of the sleeve 16'. The passage 20 serves to equalize the pressure of the upper part of the armature 3, which dips with its lower end in the control chamber 15, that is, a pressure equalization with respect to the pressure in the channel 7 and in the control chamber 15th

At the anchor 3, an upper first sealing portion 30 is also formed with a larger effective diameter and the control chamber 15 facing lower second sealing portion 28 with a smaller effective diameter, between which a conical shoulder can be formed. The sealing portions 30, 28 on the armature 3 cooperate with the sealing portions 26 and 27 of the sleeve 16 'together. In the sealing portion 28 of the armature 3, a control surface portion 26 'is provided, for example, as a straight or curved in the direction of the main piston 10 sloping longitudinal groove or control notch (alternatively a conical surface), and cooperates with the control edge 31 as the control throttle, namely directly downstream of the fixed throttle F. Is at powered Proportional 2, 2 'the pilot cone 21 lifted from the pilot seat, then decreases due to the increasing cross-section of the control throttle S and the effect of the fixed throttle F, the pressure in the control chamber 15 relative to the pressure in the annular chamber 25th About the control throttle S is formed in the closing direction oriented control force K directly at the anchor, since the load pressure in the annular chamber 25 acts on an annular surface between the smaller cross section of the upper end of the armature 3 and the larger cross section of the sealing portion 30 downwards, while on the Fixed throttle F and the current cross Nitt the control throttle S against the load pressure reduced pressure in the control chamber 15 acts on the same annular surface upwards. The pressure difference producing the control force K arises because the fixed throttle F and the control throttle S are throttled to the pressure-relieved control chamber 15, while the annular chamber 25 is acted upon directly by the load pressure from the channel 7 while bypassing the fixed throttle F. The proportional solenoid 2, 2 'regulates the amount that flows from the channel 7 into the channel 8 completely load-independent.

The course of the control force K can be a straight line in order to keep the amount constant, independently of the value of the pressure difference. If a control according to user-specific requirements is required, can be adjusted by appropriate design of Stelldrossei S or choice of the course of the control force K on the control stroke an inclined straight line or a curved curve, for example, by the corresponding design of the control surface portion 26, 26 '. In any case, the proportional solenoid 2, 2 'on the control force K imposed a feedback to the current load pressure, so that the proportional solenoid controls the amount regardless of the load pressure.

Alternatively to the proportional pressure regulating seat valves 41, 50, 50 'of Fig. 5 and 6 may also be used proportional pressure control seat valves, for example EP 0 837 275 A and EP 0 893 607 A the applicant are known.

Claims (15)

Electrohydraulic control device (EHR) of a lifting mechanism (H) of a mobile working machine (M) having at least one hydraulic motor (Z) which can be acted upon on one or two sides, wherein the control device (EHR) has a lifting strand (37) and a sinking strand (38) each with a proportional Pressure control seat valve with leak-free locking position for the load pressure, a load pressure signal circuit (LS) and an electrical control unit (CU), which is connected to the proportional magnets (2, 2 ', 55), and actual status reporting sensors (49, 51, 52), characterized in that at least the proportional pressure regulating seat valve (41, 50, 50 ') arranged in the lifting strand (37) is formed with a pressure precontrol (43) and can be actuated by the proportioning agent (2, 2') to compensate for load pressure. Electrohydraulic control device according to Claim 1, characterized in that the proportional pressure regulating seat valve (50, 50 ') arranged in the drain train (38) is also designed with a pressure precontrol and can be actuated by the proportional solenoid (2') to compensate for load pressure. Electrohydraulic control device according to claim 1, characterized in that at least the lifting strand (37) upstream of the proportional pressure regulating seat valve to a hydropneumatic gas pressure accumulator (48) is connected. Electrohydraulic control device according to claim 1, characterized in that the lifting strand (37) via a Senkundär-pressure limiting valve (47, 47 ') or a switching valve (59) with a tank (R) is connectable. Electrohydraulic control device according to claim 4, characterized in that the secondary pressure relief valve (47 ') by a proportional solenoid (55) is adjustable. Electrohydraulic control device according to claim 4, characterized in that the switching valve (59) is a black / white magnetic switching valve. Electrohydraulic control device according to claim 4, characterized in that the switching valve (59) is a 2/4-solenoid valve, which locks in a switching position the hoist strand (37) relative to a tank (R) and keeps the load pressure signal circuit (LS) open, and relieved in the other switching position the hoist strand (37) and the load pressure signal circuit (LS) to the tank (R). Electrohydraulic control device according to claim 1, characterized in that for a one-sided acted upon hydraulic motor (Z) of the load pressure signal circuit (LS), preferably via a shuttle valve (57), only to the lifting strand (37), or for a double-sided acted upon hydraulic motor (Z ) via a further shuttle valve (53) downstream of the respective proportional Druckregelsitzventils pressure-dependent on the lifting strand (37) or the drainage train (38) can be connected. Electrohydraulic control device according to claim 1, characterized in that in the pressure pilot control (43) of the proportional pressure regulating seat valve from the load pressure hydraulically on at least one anchor (3) of the proportional solenoid (2, 2 ') acting control force (K) is generated, preferably such in that, for each set value of energization of the proportional magnet (2, 2 '), the quantity flowing between the load pressure side and the low pressure side is either constant-lasting or user-specific independently of at least changes in the load pressure. Electrohydraulic control device according to claim 9, characterized in that the load pressure independently operable proportional pressure regulating seat valve (41, 50, 50 ') is formed with a valve seat (12) between the load pressure side and the low pressure side, one with the valve seat (12) cooperating, a seat surface (11) having a main piston (10) which is sealed in a control chamber (15) from the shut-off position on the valve seat, one of a pilot seat (14) in the main piston (10) and a pilot seat (14) cooperating pilot cone (21) existing pilot pressure pilot valve between the control chamber (15) and the low pressure side, a pilot cone (21) acting on the control spring (23), and the pilot valve with the armature (3) actuating proportional solenoid (2, 2 '), which when energized in at least a direction of its Stellhubes against a starting position with the pilot cone (21) can be coupled, wherein between the Lastdru back and the control chamber (15) a flow connection (18) with a fixed throttle (F) and between the fixed throttle (F) and the control chamber (15) a control throttle (S) are provided, wherein the size the control throttle (S) is variable over the control stroke of the armature (3) with the pilot valve open, and the control throttle (S) from the load pressure directly or via the pilot cone (21) at the armature (3), which depends on the pressure difference between the load pressure side and the Low-pressure side dependent control force (K) generated. Electrohydraulic control device according to claim 10, characterized in that the control spring (23) acts on the pilot cone (21) in the closing direction, that the energized proportional solenoid (2, 2 ') acts on the pilot cone (21) with the armature (3) in the opening direction of the pilot valve in that the control force (K) generated hydraulically via the control throttle (S) acts on the armature (3) in the closing direction of the pilot valve. Electrohydraulic control device according to claim 10, characterized in that the control spring acts on the pilot cone in the opening direction, that the energized proportional solenoid impinges the pilot cone with the armature in the closing direction, and that with the control throttle (S) hydraulically generated control force (K) at the armature in the opening direction the pilot valve acts. Electrohydraulic control device according to at least one of claims 9 to 12, characterized in that an auxiliary control chamber (17) is provided between the armature (3) and the control throttle (15) which communicates with the fixed throttle (F) and accommodates one end of the armature (3) which is separated from the control chamber (15) by a partition (T) having a passage (25), through which passage (25) the pilot cone (21) extends into the control chamber (15) such that the pilot cone (21) a cam portion (26) gradually increasing toward the pilot seat (14) and relative to an axis of the pilot poppet (21); and that the poppet (S) is defined by the cam portion (26) and the passage (25). Electrohydraulic control device according to at least one of claims 9 to 12, characterized in that the armature (3) extends into the control chamber (15) and with at least one sealing portion (28, 30) in a stationary sealing portion (26, 27) slidably displaceable is, which limits the control chamber (15) and communicates with the fixed throttle (F), and that the control throttle (S) between the sealing portions (28, 30, 26, 27) is defined. Electrohydraulic control device according to claim 14, characterized in that the armature (3) and a guide bore facing away from the control chamber (15) the first sealing portion (26, 30) having a larger effective diameter, and the control chamber (15) facing the second sealing portion (27, 28) having a smaller effective diameter, of which the first sealing portion (30) of the armature (3) opposite to the control chamber (15 ) sealed and communicating with the load pressure side annular chamber (25) limits that the fixed throttle (F) between the first and second sealing portions (26, 27) opens into the guide bore, that the armature (3) in the second sealing portion (28) has an in Direction to the control chamber (15) inclined sloping control surface portion (26 '), and in that on the control chamber (15) facing side of the fixed throttle (F) between the first and second sealing portions (26, 27) is provided a circumferential control edge (31) , which defines with the control surface portion (26) the here blind-like control throttle (S).

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