EP0968334A1 - Hydraulic control system for a mobile work machine, especially a wheel loader - Google Patents

Hydraulic control system for a mobile work machine, especially a wheel loader

Info

Publication number
EP0968334A1
EP0968334A1 EP98916979A EP98916979A EP0968334A1 EP 0968334 A1 EP0968334 A1 EP 0968334A1 EP 98916979 A EP98916979 A EP 98916979A EP 98916979 A EP98916979 A EP 98916979A EP 0968334 A1 EP0968334 A1 EP 0968334A1
Authority
EP
European Patent Office
Prior art keywords
valve
hydraulic
pressure
control
directional
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP98916979A
Other languages
German (de)
French (fr)
Other versions
EP0968334B1 (en
Inventor
Georg Rausch
Dieter Roth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bosch Rexroth AG
Original Assignee
Mannesmann Rexroth AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mannesmann Rexroth AG filed Critical Mannesmann Rexroth AG
Publication of EP0968334A1 publication Critical patent/EP0968334A1/en
Application granted granted Critical
Publication of EP0968334B1 publication Critical patent/EP0968334B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E02F9/2207—Arrangements for controlling the attitude of actuators, e.g. speed, floating function for reducing or compensating oscillations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2267—Valves or distributors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators

Definitions

  • the invention is based on a hydraulic control arrangement which is used for a mobile working machine, in particular for a wheel loader, and which has the features from the preamble of claim 1.
  • the shut-off valve between the hydraulic accumulator and the lift cylinders is closed as long as the loading shovel is in use and can be opened by the driver or automatically as soon as pitching vibrations occur while driving or as soon as the driving speed exceeds a certain value, e.g. over 6 km / h lies.
  • the branching of the filling line in front of the directional control valve block means that the hydraulic accumulator not only when the directional valve assigned to the lift cylinders is actuated, but also when which is charged when any directional valve is actuated, which leads to pressure build-up in the pump line.
  • the actuation of the steering valve belonging to a hydraulic steering of the working machine can also lead to an inflow of pressure medium to the hydraulic accumulator. If the check valve is also open, the lift cylinders can move in an uncontrolled manner.
  • the invention is based on the object of further developing a hydraulic control arrangement with the features from the preamble of claim 1 in such a way that uncontrolled movements of the hydraulic cylinder which can be connected to the hydraulic accumulator for damping pitching vibrations of the working machine are largely avoided.
  • the hydraulic cylinder is usually a double-acting one, which can be controlled with the aid of a directional control valve, which can be adjusted from a middle rest position into two opposite directions in working positions.
  • a directional control valve which can be adjusted from a middle rest position into two opposite directions in working positions.
  • the hydraulic accumulator can only be filled in one direction when the directional valve is actuated. This simplifies the control arrangement. With a wheel loader e.g. it will suffice if the hydraulic accumulator can only receive pressure fluid when the directional valve is actuated in the direction of lifting the lift cylinder.
  • a control valve is advantageously used to control the fillability of the hydraulic accumulator, which by actuating the directional control valve from a first switch position, in which it prevents the hydraulic accumulator from being filled, in which the filling line is therefore blocked in such a way that also then no pressure medium flows to the hydraulic accumulator when the pump pressure or the load pressure is higher than the accumulator pressure, can be switched to a second switching position in which the hydraulic accumulator can be filled.
  • the switchable by operating the directional control valve is advantageously a seat valve, so that a largely leak-free shut-off of the filling line is guaranteed.
  • Directional valves that are used in mobile hydraulics are nowadays no longer controlled directly mechanically, but rather via pilot signals that can be specified using a pilot control device.
  • a pilot signal for the directional control valve is now also used to bring about a control signal for switching the control valve from the first switching position into the second switching position.
  • the filling line branches off from a working line running between the directional control valve and the hydraulic cylinder and in the filling line there is a pressure-controlled shut-off valve with a valve member which is dependent on the load pressure prevailing in the working line in the opening direction and on the pressure in a rear control room can be acted upon in the closing direction.
  • the rear control room is connected to the hydraulic accumulator.
  • the rear control room to the tank is relieved.
  • the rear control chamber can be blocked against the discharge of pressure medium. The check valve can then not be opened by the load pressure.
  • Claims 7 to 10 contain advantageous developments of a hydraulic control arrangement according to claim 6.
  • Several exemplary embodiments of a hydraulic control arrangement according to the invention are shown in the drawings. The invention will now be explained in more detail using these exemplary embodiments.
  • Figure 1 shows the first embodiment in which the filling line is connected to the working line leading to two hydraulic cylinders and is in the filling line
  • Check valve is located, which is controlled by two electromagnetically actuated pilot valves
  • Figure 2 shows the second embodiment, which is largely identical to the first embodiment and in which two individual pilot valves of the first embodiment are combined to form a single pilot valve
  • Figure 3 shows the third embodiment which branches off the filling line from the pump line in front of the directional control valve and a control valve is located in the filling line, with which the filling line can be shut off when the directional control valve is not actuated.
  • the hydraulic control arrangements shown are each intended for wheel loaders, tractors, telescopic handlers or other machines and comprise a control block 10 with a plurality of directional control valves, in particular also with a directional control valve 11, which can assume a spring-centered central position and can be controlled with the two hydraulic cylinders 12 designed as differential cylinders with which the boom of a wheel loader is lifted and can be lowered.
  • the directional control valve 11 has a first working connection 13, from which a first working line 14 leads to the pressure chambers 15 on the bottom side of the hydraulic cylinders 12.
  • a second working line 16 runs between a second working connection 17 of the directional control valve 11 and the pressure chambers 18 of the hydraulic cylinders 12 on the piston rod side.
  • a filling line 20 branches off from the working line 14 and leads to a hydraulic accumulator 21.
  • a check valve 22 is arranged in the filling line, which is designed as a 2-way cartridge valve and has a movable valve member 23.
  • This is a stepped piston, which can sit on a seat cone with the end face of the piston section, which is smaller in diameter, in the manner of a seat valve.
  • the valve member 23 is acted upon by the pressure prevailing in the working line 14, that is to say by the load pressure of the two hydraulic cylinders 12 in the opening direction.
  • the accumulator pressure acts in the opening direction on the annular surface between the two piston sections of the valve member 23.
  • the valve member 23 is acted upon by a pressure prevailing in a rear control chamber 24 and by a weak compression spring 25.
  • the first valve 30 is a 3/2
  • Directional control valve with a first inlet 31, which is connected to the section of the filling line 20 between the working line 14 and the check valve 22, and with a second inlet 32, which is connected to the hydraulic accumulator 21.
  • On Output 33 of the directional control valve 30 can be connected either to the input 31 or to the input 32, depending on the load pressure in the working line 14.
  • an adjustable compression spring acts on the valve member of the valve 30, which is not shown in detail.
  • the valve member is affected by the pressure in the input 31, that is, Load pressure of the hydraulic cylinder 12 is applied.
  • a pilot valve 40 is placed on the directional control valve 30, which is designed as a 2/2-way seat valve and can be regarded as an unlockable check valve.
  • a control channel 41 extending from the outlet 33 of the directional control valve 30 leads to a connection P of a further pilot valve 50, which is a 4/2 way valve.
  • Whose valve member assumes a rest position under the action of a compression spring 51, in the passage between the port P and a port A, which is connected to a connection of the pilot valve 40.
  • a tank connection T and a further connection B of the pilot valve 50 are blocked in its rest position.
  • the tank connection is connected to a leakage connection Y of the plate 26 via channels leading through the housings of the various valves.
  • connection B of the pilot valve 50 is connected to the rear control chamber of a second 2-way built-in valve 60 located in the plate 26, via which the piston rod-side pressure chambers 18 of the hydraulic cylinders 12 can be connected to a tank connection T of the plate 26.
  • the valve member of the pilot valve 50 can be brought into a switching position by an electromagnet 52, in which the port P is closed and the two ports A and B are connected to the port T.
  • the pilot valve 40 is arranged in a line 53 between the connection A of the pilot valve 50 and the rear control chamber 24 of the check valve 22. Its valve member is acted upon by a compression spring 42 and by the pressure prevailing in the rear control chamber of the check valve 22 in the direction of a rest position, in which it prevents an outflow of pressure medium from the rear control chamber 24 to port A of the pilot valve 50, an inflow of pressure medium from the port A of the pilot valve 50 to the rear control chamber 24, however, allows.
  • the valve member can be brought by an electromagnet 43 into a switching position in which there is a free passage between the connection A of the pilot valve 50 and the rear control chamber 24 of the check valve 22.
  • the directional control valve 11 of the control block 10 can be actuated in a hydraulically proportional manner, the pilot control pressures being generated with the aid of a hydraulic pilot control device 55 and being supplied to the directional control valve 11 via control lines 56.
  • An electrical pressure switch 57 is connected to the pilot line, into which a pilot pressure is introduced when the hydraulic cylinders 12 are to be actuated in the direction of lifting the boom and for this purpose pressure medium is applied to the bottom pressure chambers 15, which switches over at a specific pilot pressure.
  • This specific pilot pressure is preferably the pilot pressure at which the spring-centered valve spool of the directional control valve 11 begins to move.
  • the solenoid 52 of the pilot valve 50 is activated arbitrarily by the driver when pitching vibrations occur, or automatically at a certain speed of the mobile working machine, e.g. at a speed of 6 km / h put on tension.
  • the hydraulic accumulator 21 is therefore not influenced in its state of charge by the pressure build-up in the pressure chambers 15. The same applies if the directional valve is actuated in the direction of lowering the hydraulic cylinder 12. The pilot valve 40 then remains in the switching position shown, so that the check valve 22 cannot be opened by the pressure in the pressure chambers 15 of the hydraulic cylinders 12.
  • the pressure switch 57 switches over, as a result of which the electromagnet 43 is actuated and the valve member of the pilot valve 40 reaches the second switching position.
  • the pressure in the pressure chambers 15 remains below the pressure set on the compression spring 34 of the directional control valve 30, this switches the accumulator pressure through via the pilot valve 50 and the pilot valve 40 to the rear control chamber 24 of the check valve 22.
  • the load pressure in the pressure chambers 15 of the hydraulic cylinders 12 now opens the shut-off valve 22 whenever it is at least the small pressure difference equivalent to the force of the compression spring 25 above the storage pressure.
  • Pressure medium can then get into the hydraulic accumulator so that, if one looks at the force of the weak compression spring 25, it is always charged to the greatest load pressure in the pressure chambers 15 that occurs during a working cycle.
  • the check valve 22 remains closed only when the load pressure at the valve 30 can overcome the force of the compression spring 34. After a switchover of the valve 30, the load pressure is present in the rear control chamber 24 of the check valve 22, so that the check valve 22 is held securely in conjunction with the compression spring 25.
  • the pressure in the hydraulic accumulator 21 can therefore not exceed the value set on the compression spring 34 of the valve 30.
  • a pressure limiting valve 58 is additionally provided, the input of which is connected to the hydraulic accumulator 21.
  • both magnets 43 and 52 of the pilot valves 40 and 50 are energized so that both pilot valves switch from the rest positions shown in FIG. 1 to the other switching position.
  • the rear control chamber 24 of the check valve 22 is connected via the pilot valve 40 and via the pilot valve 50 to the connection Y of the plate 26 and is thus relieved to the tank 27.
  • the valve member 23 of the check valve 22 is lifted from its seat by load and accumulator pressure, so that there is an open connection between the hydraulic accumulator 21 and the pressure chambers 15 of the hydraulic cylinders 12.
  • the accumulator pressure 21 corresponds to the maximum pressure reached during the working cycle, when the shut-off valve 22 is opened there is no sagging, but rather a slight lifting of the loading shovel. It may be the case that load pressures occur during the working cycle which cause the valve 30 to switch and which therefore do not follow the state of charge of the hydraulic accumulator 21. However, these load pressures only occur in special situations, for example when an object anchored in the ground is torn away or when the loading shovel moves against a stop, but are not caused by the weight of the loading shovel and the load that only acts when the wheel loader is driving. The state of charge of the hydraulic accumulator 21 is therefore always sufficient to keep the loading shovel at the level which it assumes when the check valve 22 is opened.
  • pressure medium can be drawn from the piston rod side.
  • gen pressure spaces 18 of the hydraulic cylinder 12 are displaced into the tank or fed from the tank to compensate for volume changes in the pressure spaces 18, which occur during the open connection of the pressure spaces 15 to the hydraulic accumulator 21.
  • the embodiment according to FIG. 2 differs from that according to FIG. 1 only with regard to the pilot valves 40 and 50. Therefore, with regard to the control block 10, the hydraulic cylinders 12, the hydraulic accumulator 21, the check valves 22 and 60, the directional control valve 30 and the pilot control unit 55 refers to the corresponding description of FIG. 1. Different from the embodiment according to FIG. 1 is that the two pilot valves 40 and 50 are now combined to form a single pilot valve 60 which is placed on the directional control valve 30.
  • the pilot valve 60 has a spring-centered central position, in which the connections T and B are shut off and only a flow from P to A is possible between the connections P and A.
  • the valve member of the pilot valve 60 can be brought out of the central position into a lateral switching position in which the connections A and B are connected to the connection T by driving an electromagnet 52. From the middle position in the opposite direction, the valve member can be adjusted by acting on the pressure prevailing in the pilot line 56, in which a pilot pressure is built up to supply pressure medium into the bottom-side pressure chambers 15 of the hydraulic cylinders 12. In this other switching position of the directional control valve 60, the connection A is freely connected to the connection P. The connection A is now connected directly to the rear control chamber 24 of the check valve 22.
  • the pilot valve 60 In the middle position or in the lower position of the directional control valve 11, the pilot valve 60 assumes its middle position provided the speed of the working machine does not exceed a certain value or the electromagnet 52 has not been switched on arbitrarily.
  • the valve member of the directional valve 60 In the raised position of the directional valve 11, the valve member of the directional valve 60 is pressurized and reaches the switch position in which the port P is connected to the port A.
  • the accumulator pressure or the load pressure is then present in the rear control chamber 24 of the check valve 22. The hydraulic accumulator is charged up to the maximum load pressure reached or up to the pressure set on the compression spring 34 of the valve 30.
  • the electromagnet 52 is excited so that the valve member of the directional control valve 60 reaches the switching position in which the connections A and B are connected to the connection T.
  • the rear control chambers of the check valves 22 and 60 are relieved of pressure, so that the two check valves 22 and 60 open and there is an open connection between the hydraulic accumulator 21 and the pressure chambers 15 of the hydraulic cylinders 12 and displaces pressure medium from the pressure chambers 18 and into the pressure chambers 18 Pressure fluid can be fed.
  • the pressure at the connection T of a valve block is usually a few bar above the tank pressure prevailing at the drain port Y, so that the check valve 60 is opened by the pressure at the tank connection T against the tank pressure in the rear control chamber can. It is particularly advantageous that after slowing down and de-energization of the electromagnets 43 and 52 in the embodiment according to FIG. 1 and the electromagnet 52 alone in the embodiment according to FIG 24 of the check valve 22 is controlled and therefore closes the check valve. Influencing the hydraulic accumulator 21 or influencing the hydraulic accumulator 21 on the control system is then ruled out when the hydraulic cylinders 12 are subsequently lowered or the blade is unloaded, during which the directional control valve 11 is in its central position.
  • the filling line 20 branches off from a pump line 65 in front of the valve control block 10.
  • a 2/2-way valve 70, a pressure control valve 71 and a check valve 72 are first arranged in the filling line 20 leading to a plurality of hydraulic accumulators 21, as seen in the flow direction of the pressure medium from the pump line 65 to the hydraulic cylinders 21.
  • the directional valve 70 In the rest position of the directional valve 70, which is brought about by a compression spring, its two connections are shut off from one another.
  • the directional control valve can be switched into a through position by driving an electromagnet 73.
  • the electromagnet 73 is always energized when the directional valve 11 located within the control block 10 is actuated in the direction of lifting in order to actuate the hydraulic cylinders 12.
  • the directional valve 70 In the middle position of the directional valve 11 and when it is actuated in the direction of lowering, the directional valve 70 is in its initial position.
  • a maximum pressure is set at the pressure control valve 71, up to which the hydraulic accumulators 21 can be charged. As long as this pressure is not reached, the pressure control valve switches through the output of the directional valve 70 to the check valve 72.
  • the inlet of the valve 71 connected to the outlet of the directional control valve 70 is blocked and the connection connected to the check valve is connected to the tank.
  • the hydraulic accumulators 21 can be connected via a line 74 to the working line 14 running between the working connection 13 of the directional control valve and the pressure chambers 15 of the hydraulic cylinders 12.
  • a 4/2 way valve 75 is installed, which, under the action of a compression spring 76, assumes a rest position in which two sections of the line 74 are shut off from one another and thus there is no connection between the hydraulic accumulators 21 and the working line 14 .
  • the directional control valve 75 has two further connections for two sections of a line 77 which leads from the working line 15 between the directional control valve 11 and the pressure chambers 18 of the hydraulic cylinders 12 to the tank 27.
  • the two sections of the line 77 are also shut off from one another.
  • the directional control valve 75 can be brought into a switching position by an electromagnet 78, in which the two sections of the line 74 and the two sections of the line 77 are connected to one another.
  • the electromagnet 78 is energized when the working machine equipped with the hydraulic control arrangement shown shows a agreed driving speed exceeds. Then the hydraulic accumulators 21 are connected to the pressure chambers 15 of the hydraulic cylinders 12, so that pitching vibrations can be damped. Changes in volume of the pressure chambers 18 can be compensated for via the line 77.
  • the electromagnet 73 of the directional control valve 70 is only energized when the directional control valve 11 is actuated in the direction of lifting the hydraulic cylinders 12, ie when pressure medium 15 is supplied to the pressure chambers, the hydraulic accumulators 21 can only be charged. For example, do not happen that when there is pressure in line 65 while the working machine is traveling fast, pressure medium enters pressure chambers 15 of hydraulic cylinders 12 via filling line 20 and valve 75 switched during fast travel, even if directional control valve 11 is in

Abstract

The invention relates to a hydraulic control system for use predominantly for a mobile working machine, especially a wheel loader, comprising at least one hydraulic cylinder (12) which helps to move the working tool, a distribution valve (11) for controlling the pressure channels between the hydraulic cylinder (12), a pressure source and a tank (27), a hydraulic accumulator (21) which can be connected to the pressure source via a filling line (20) and a control valve (50, 60, 75). Said control valve provides the means for controlling the opening and closing of a connection between the hydraulic accumulator (21) and the hydraulic cylinder (12). The aim of a hydraulic control system of this type is to avoid unwanted movements of the hydraulic cylinder. According to the invention, the inventive hydraulic accumulator can only be filled up when the distribution valve is activated in order to achieve this aim.

Description

Beschreibungdescription
Hydraulische Steueranordnunσ für eine mobile Arbeitsmaschine, insbesondere für einen RadladerHydraulic Steueranordnunσ for a mobile machine, especially for a wheel loader
Der Erfindung geht aus von einer hydraulischen Steueranordnung, die für eine mobile Arbeitsmaschine, insbesondere für einen Radlader verwendet wird und die die Merkmale aus dem Oberbegriff des Anspruchs 1 aufweist.The invention is based on a hydraulic control arrangement which is used for a mobile working machine, in particular for a wheel loader, and which has the features from the preamble of claim 1.
Aus der DE 39 09 205 Cl ist es bekannt, die Nickschwingungen von Radladern, die insbesondere bei gefüllter Ladeschaufel und höherer Fahrgeschwindigkeit auftreten, mit einem Dämpfungssystem zu dämpfen, das Bestandteil der hydraulischen Steueranord- nung des Radladers ist. Zur Schwingungsdämpfung sind die im allgemeinen zwei hydraulischen Liftzylinder zum Heben und Senken der Ladeschaufel über ein Sperrventil an einen Hydrospeicher anschließbar, der von einer Hydropumpe über eine Füllei- tung, die vor dem Wegeventilsteuerblock von der Pumpenleitung abzweigt, aufgeladen werden kann. Das zwischen dem Hydrospeicher und den Liftzylindern angeordnete Absperrventil ist geschlossen, solange mit der Ladeschaufel gearbeitet wird, und kann vom Fahrer oder automatisch geöffnet werden, sobald beim Fahren Nickschwingungen auftreten oder sobald die Fahrgeschwin- digkeit über einem bestimmten Wert, z.B. über 6 km/Std. liegt.From DE 39 09 205 Cl it is known to dampen the pitching vibrations of wheel loaders, which occur in particular when the loading shovel is full and at a higher driving speed, with a damping system which is part of the hydraulic control arrangement of the wheel loader. To dampen vibrations, the generally two hydraulic lift cylinders for lifting and lowering the loading shovel can be connected via a check valve to a hydraulic accumulator, which can be charged by a hydraulic pump via a filling line that branches off the pump line in front of the directional control valve block. The shut-off valve between the hydraulic accumulator and the lift cylinders is closed as long as the loading shovel is in use and can be opened by the driver or automatically as soon as pitching vibrations occur while driving or as soon as the driving speed exceeds a certain value, e.g. over 6 km / h lies.
Die Abzweigung der Fülleitung vor dem Wegeventilsteuerblock bringt es mit sich, daß der Hydrospeicher nicht nur bei einer Betätigung des den Liftzylindern zugeordneten Wegeventils, son- dern bei einer Betätigung jedweden Wegeventils, die zu einem Druckaufbau in der Pumpenleitung führt, aufgeladen wird. Z.B. kann auch die Betätigung des zu einer hydraulischen Lenkung der Arbeitsmaschine gehörenden Lenkventils zu einem Zufluß von Druckmittel zum Hydrospeicher führen. Ist dann auch noch das Sperrventil offen, so kann eine unkontrollierte Bewegung der Liftzylinder stattfinden.The branching of the filling line in front of the directional control valve block means that the hydraulic accumulator not only when the directional valve assigned to the lift cylinders is actuated, but also when which is charged when any directional valve is actuated, which leads to pressure build-up in the pump line. For example, the actuation of the steering valve belonging to a hydraulic steering of the working machine can also lead to an inflow of pressure medium to the hydraulic accumulator. If the check valve is also open, the lift cylinders can move in an uncontrolled manner.
Ein anderes DämpfungsSystem gegen Nickschwingungen, das eben- falls Teil der hydraulischen Steueranordnung einer Arbeitsmaschine ist, ist aus der DE 41 29 509 C2 bekannt. Dabei zweigt die Fülleitung von einer Arbeitsleitung ab, die zwischen den Liftzylindern und dem diesen zugeordneten Wegeventil verläuft. Das in der Fülleitung angeordnete Sperrventil ist druckgesteu- ert und kann von dem in der Arbeitsleitung herrschendenAnother damping system against pitching vibrations, which is also part of the hydraulic control arrangement of a work machine, is known from DE 41 29 509 C2. The filling line branches off from a working line that runs between the lift cylinders and the directional valve assigned to them. The check valve in the filling line is pressure-controlled and can be different from that in the working line
Lastdruck der Liftzylinder gegen den Speicherdruck, von dem ein rückwärtiger Steuerraum am Ventilglied des Sperrventils beaufschlagbar ist, und gegen die Kraft einer schwachen Druckfeder geöffnet werden. Der Speicherdruck ist also jeweils nur gering- fügig kleiner als der während eines Arbeitsspiels auftretende höchste Lastdruck der Liftzylinder. Zur Dämpfung der Nickschwingungen wird der rückwärtige Steuerraum des Sperrventils über ein Pilotventil zum Tank entlastet, so daß das Sperrventil öffnet und Druckmittel frei zwischen dem Hydrospeicher und den Liftzylindern hin und her geschoben werden kann.Load pressure of the lift cylinder against the accumulator pressure, from which a rear control chamber on the valve member of the check valve can be acted upon, and opened against the force of a weak compression spring. The accumulator pressure is therefore only slightly lower than the highest load pressure of the lift cylinder that occurs during a work cycle. To dampen the pitching vibrations, the rear control chamber of the check valve is relieved to the tank via a pilot valve, so that the check valve opens and pressure medium can be freely pushed back and forth between the hydraulic accumulator and the lift cylinders.
Es hat sich nun gezeigt, daß aufgrund besonderer kinematischer Verhältnisse an einem Radlader beim Einstechen der Schaufel in die Erde in den Liftzylindern ein höherer Druck aufgebaut wer- den kann, als er im Hydrospeicher herrscht, und dann Druckmittel aus den Liftzylindern in den Hydrospeicher verdrängt wird, selbst wenn das zugeordnete Wegeventil nicht betätigt ist. Der Radlader wird vorne angehoben, so daß die Vorderräder in der Luft drehen und die Hinterräder sich eingraben. Dies ist für den Ladevorgang nachteilig.It has now been shown that due to special kinematic conditions on a wheel loader, when the bucket is inserted into the ground, a higher pressure is built up in the lift cylinders. can, when it is in the hydraulic accumulator, and then pressure medium is displaced from the lift cylinders into the hydraulic accumulator, even if the assigned directional valve is not actuated. The front loader is raised so that the front wheels spin in the air and the rear wheels dig in. This is disadvantageous for the charging process.
Der Erfindung liegt die Aufgabe zugrunde, eine hydraulische Steueranordnung mit den Merkmalen aus dem Oberbegriff des An- Spruchs 1 so weiterzuentwickeln, daß unkontrollierte Bewegungen des zur Dämpfung von Nickschwingungen der Arbeitsmaschine mit dem Hydrospeicher verbindbaren Hydrozylinders weitgehend vermieden werden.The invention is based on the object of further developing a hydraulic control arrangement with the features from the preamble of claim 1 in such a way that uncontrolled movements of the hydraulic cylinder which can be connected to the hydraulic accumulator for damping pitching vibrations of the working machine are largely avoided.
Dieses Ziel wird bei einer hydraulischen Steueranordnung mit den Merkmalen aus dem Oberbegriff des Anspruchs 1 erfindungsgemäß dadurch erreicht, daß der Hydrospeicher nur auffüllbar ist, wenn das Wegeventil, das dem Hydrozylinder zugeordnet ist, betätigt ist. Somit kann bei einer Betätigung eines anderen Wege- ventils kein Druckmittel dem Hydrospeicher zufließen, so daß die Betätigung eines anderen Wegeventils nicht zu einer Bewegung des Hydrozylinders führen kann. Ebenso wird verhindert, daß bei nicht betätigtem Wegeventil aus dem Hydrozylinder Druckmittel in den Hydrospeicher verdrängt wird. Das einge- schlossene Druckmittel verhindert deshalb eine Bewegung des Zylinderkolbens und damit eine Veränderung der relativen Lage zwischen dem Ausleger und dem Körper der Arbeitsmaschine, so daß ein Anheben der Vorderachse verhindert wird. Vorteilhafte Ausgestaltungen einer hydraulischen Steueranordnung kann man den Unteransprüchen entnehmen.This aim is achieved according to the invention in a hydraulic control arrangement with the features from the preamble of claim 1 in that the hydraulic accumulator can only be refilled if the directional valve which is assigned to the hydraulic cylinder is actuated. Thus, when another directional control valve is actuated, no pressure medium can flow into the hydraulic accumulator, so that the actuation of another directional control valve cannot lead to a movement of the hydraulic cylinder. It also prevents pressure medium from being displaced from the hydraulic cylinder into the hydraulic accumulator when the directional control valve is not actuated. The enclosed pressure medium therefore prevents movement of the cylinder piston and thus a change in the relative position between the boom and the body of the working machine, so that the front axle is prevented from lifting. Advantageous configurations of a hydraulic control arrangement can be found in the subclaims.
Üblicherweise ist der Hydrozylinder ein doppeltwirkender und mit Hilfe eines Wegeventils steuerbar, das aus einer mittleren Ruhestellung heraus nach zwei entgegengesetzten Richtungen in Arbeitsstellungen verstellbar ist. Gemäß Anspruch 2 ist vorgesehen, daß der Hydrospeicher nur bei einer Betätigung des Wegeventils in die eine Richtung auffüllbar ist. Die Steueranord- nung vereinfacht sich dadurch. Bei einem Radlader z.B. wird es genügen, wenn dem Hydrospeicher nur bei einer Betätigung des Wegeventils in Richtung Heben der Liftzylinder Druckmittel zufließen kann.The hydraulic cylinder is usually a double-acting one, which can be controlled with the aid of a directional control valve, which can be adjusted from a middle rest position into two opposite directions in working positions. According to claim 2 it is provided that the hydraulic accumulator can only be filled in one direction when the directional valve is actuated. This simplifies the control arrangement. With a wheel loader e.g. it will suffice if the hydraulic accumulator can only receive pressure fluid when the directional valve is actuated in the direction of lifting the lift cylinder.
Gemäß Anspruch 3 wird zur Steuerung der Befüllbarkeit des Hy- drospeichers vorteilhafterweise ein Steuerventil verwendet, das durch eine Betätigung des Wegeventils aus einer ersten Schalt- stellung, in der es ein Befüllen des Hydrospeichers verhindert, in der also die Fülleitung so abgesperrt ist, daß auch dann kein Druckmittel dem Hydrospeicher zufließt, wenn der Pumpendruck oder der Lastdruck höher als der Speicherdruck ist, in eine zweite Schaltstellung umschaltbar ist, in der der Hydrospeicher befüllbar ist.According to claim 3, a control valve is advantageously used to control the fillability of the hydraulic accumulator, which by actuating the directional control valve from a first switch position, in which it prevents the hydraulic accumulator from being filled, in which the filling line is therefore blocked in such a way that also then no pressure medium flows to the hydraulic accumulator when the pump pressure or the load pressure is higher than the accumulator pressure, can be switched to a second switching position in which the hydraulic accumulator can be filled.
Das durch eine Betätigung des Wegeventils umschaltbare Steuerventil ist vorteilhafterweise ein Sitzventil, so daß eine weitgehend leckagefreie Absperrung der Fülleitung gewährleistet ist. Grundsätzlich ist es denkbar, das durch eine Betätigung des Wegeventils umschaltbare Steuerventil mechanisch mit diesem zu koppeln. Wegeventile, die in der Mobilhydraulik verwendet werden, werden heute immer öfter nicht mehr direkt mechanisch, sondern über mithilfe eines Vorsteuergerätes vorgebbaren Vorsteuersignalen angesteuert. Gemäß Anspruch 5 wird nun ein Vorsteuersignal für das Wegeventil auch dazu genutzt, um ein Steuersignal zur Umschaltung des Steuerventils von der ersten Schaltstellung in die zweite Schaltstellung herbeizuführen.The switchable by operating the directional control valve is advantageously a seat valve, so that a largely leak-free shut-off of the filling line is guaranteed. In principle, it is conceivable to mechanically couple the control valve which can be switched over by actuating the directional valve. Directional valves that are used in mobile hydraulics are nowadays no longer controlled directly mechanically, but rather via pilot signals that can be specified using a pilot control device. According to claim 5, a pilot signal for the directional control valve is now also used to bring about a control signal for switching the control valve from the first switching position into the second switching position.
Besonders bevorzugt wird eine Ausgestaltung gemäß Anspruch 6, nach dem die Fülleitung von einer zwischen dem Wegeventil und dem Hydrozylinder verlaufenden Arbeitsleitung abzweigt und sich in der Fülleitung ein druckgesteuertes Sperrventil mit einem Ventilglied befindet, das vom in der Arbeitsleitung herrschenden Lastdruck in Öffnungsrichtung und vom Druck in einem rückwärtigen Steuerraum in Schließrichtung beaufschlagbar ist. Zum Befüllen des Hydrospeichers ist der rückwärtige Steuerraum mit dem Hydrospeicher verbunden. Zur Dämpfung der Nickschwingungen der Arbeitsmaschine muß eine offene Verbindung zwischen dem Hydrospeicher und dem Hydrozylinder vorhanden sein. Dazu wird der rückwärtige Steuerraum zum Tank entlastet. Um ein Befüllen des Hydrospeichers zu verhindern, wenn das Wegeventil nicht betätigt ist, ist der rückwärtige Steuerraum gegen den Abfluß von Druckmittel absperrbar. Das Sperrventil kann dann vom Lastdruck nicht geöffnet werden.Particularly preferred is an embodiment according to claim 6, according to which the filling line branches off from a working line running between the directional control valve and the hydraulic cylinder and in the filling line there is a pressure-controlled shut-off valve with a valve member which is dependent on the load pressure prevailing in the working line in the opening direction and on the pressure in a rear control room can be acted upon in the closing direction. To fill the hydraulic accumulator, the rear control room is connected to the hydraulic accumulator. To dampen the pitching vibrations of the working machine, there must be an open connection between the hydraulic accumulator and the hydraulic cylinder. For this purpose, the rear control room to the tank is relieved. In order to prevent the hydraulic accumulator from being filled when the directional control valve is not actuated, the rear control chamber can be blocked against the discharge of pressure medium. The check valve can then not be opened by the load pressure.
Die Ansprüche 7 bis 10 enthalten vorteilhafte Weiterbildungen einer hydraulischen Steueranordnung gemäß Anspruch 6. Mehrere Ausführungsbeispiele einer erfindungsgemäßen hydraulischen Steueranordnung sind in den Zeichnungen dargestellt. Anhand dieser Ausführungsbeispiele wird die Erfindung nun näher erläutert.Claims 7 to 10 contain advantageous developments of a hydraulic control arrangement according to claim 6. Several exemplary embodiments of a hydraulic control arrangement according to the invention are shown in the drawings. The invention will now be explained in more detail using these exemplary embodiments.
Es zeigenShow it
Figur 1 das erste Ausführungsbeispiel, bei dem die Fülleitung an die zu zwei Hydrozylindern führende Arbeitsleitung angeschlossen ist und sich in der Fülleitung einFigure 1 shows the first embodiment in which the filling line is connected to the working line leading to two hydraulic cylinders and is in the filling line
Sperrventil befindet, das von zwei elektromagnetisch betätigbaren Pilotventilen gesteuert wird, Figur 2 die zweite Ausführung, die weitgehend gleich der ersten Ausführung aufgebaut ist und bei der zwei einzelne Pilotventile der ersten Ausführung zu einem einzigen Pilotventil zusammengefaßt sind, und Figur 3 die dritte Ausführung, bei der die Fülleitung vor dem Wegeventil von der Pumpenleitung abzweigt und sich in der Fülleitung ein Steuerventil befindet, mit dem bei nicht betätigtem Wegeventil die Fülleitung absperrbar ist.Check valve is located, which is controlled by two electromagnetically actuated pilot valves, Figure 2 shows the second embodiment, which is largely identical to the first embodiment and in which two individual pilot valves of the first embodiment are combined to form a single pilot valve, and Figure 3 shows the third embodiment which branches off the filling line from the pump line in front of the directional control valve and a control valve is located in the filling line, with which the filling line can be shut off when the directional control valve is not actuated.
Die gezeigten hydraulischen Steueranordnungen sind jeweils für Radlader, Traktoren, Teleskop-Handler oder andere Maschinen vorgesehen und umfassen einen Steuerblock 10 mit mehreren Wegeventilen, insbesondere auch mit einem Wegeventil 11, das eine federzentrierte Mittelstellung einnehmen kann und mit dem zwei als Differentialzylinder ausgebildete Hydrozylinder 12 ansteuerbar sind, mit denen der Ausleger eines Radladers gehoben und abgesenkt werden kann. Das Wegeventil 11 besitzt einen ersten Arbeitsanschluß 13, von dem eine erste Arbeitsleitung 14 zu den bodenseitigen Druckräumen 15 der Hydrozylinder 12 führt. Eine zweite Arbeitsleitung 16 verläuft zwischen einem zweiten Ar- beitsanschluß 17 des Wegeventils 11 und den kolbenstangenseiti- gen Druckräumen 18 der Hydrozylinder 12.The hydraulic control arrangements shown are each intended for wheel loaders, tractors, telescopic handlers or other machines and comprise a control block 10 with a plurality of directional control valves, in particular also with a directional control valve 11, which can assume a spring-centered central position and can be controlled with the two hydraulic cylinders 12 designed as differential cylinders with which the boom of a wheel loader is lifted and can be lowered. The directional control valve 11 has a first working connection 13, from which a first working line 14 leads to the pressure chambers 15 on the bottom side of the hydraulic cylinders 12. A second working line 16 runs between a second working connection 17 of the directional control valve 11 and the pressure chambers 18 of the hydraulic cylinders 12 on the piston rod side.
Bei der Ausführung nach Figur 1 zweigt von der Arbeitsleitung 14 eine Fülleitung 20 ab, die zu einem Hydrospeicher 21 führt. In der Fülleitung ist ein Sperrventil 22 angeordnet, das als 2- Wege-Einbauventil ausgebildet ist und ein bewegliches Ventilglied 23 aufweist. Dieses ist ein Stufenkolben, der mit der Stirnseite des im Durchmesser kleineren Kolbenabschnitts nach Art eines Sitzventils auf einem Sitzkegel aufsitzen kann. An der besagten Stirnfläche wird das Ventilglied 23 vom in der Arbeitsleitung 14 herrschenden Druck, also vom Lastdruck der beiden Hydrozylinder 12 in Öffnungsrichtung beaufschlagt. An der Ringfläche zwischen den beiden Kolbenabschnitten des Ventig- lieds 23 wirkt der Speicherdruck in Öffnungsrichtung. In Schließrichtung wird das Ventilglied 23 von einem in einem rückwärtigen Steuerraum 24 herrschenden Druck und von einer schwachen Druckfeder 25 beaufschlagt.In the embodiment according to FIG. 1, a filling line 20 branches off from the working line 14 and leads to a hydraulic accumulator 21. A check valve 22 is arranged in the filling line, which is designed as a 2-way cartridge valve and has a movable valve member 23. This is a stepped piston, which can sit on a seat cone with the end face of the piston section, which is smaller in diameter, in the manner of a seat valve. On the said end face, the valve member 23 is acted upon by the pressure prevailing in the working line 14, that is to say by the load pressure of the two hydraulic cylinders 12 in the opening direction. The accumulator pressure acts in the opening direction on the annular surface between the two piston sections of the valve member 23. In the closing direction, the valve member 23 is acted upon by a pressure prevailing in a rear control chamber 24 and by a weak compression spring 25.
Auf die Platte 26 mit dem 2 -Wege-Einbauventil 22 sind drei wei- tere Ventile aufgebaut. Das erste Ventil 30 ist ein 3/2-Three further valves are built on the plate 26 with the 2-way cartridge valve 22. The first valve 30 is a 3/2
Wegeventil mit einem ersten Eingang 31, der mit dem zwischen der Arbeitsleitung 14 und dem Sperrventil 22 befindlichen Abschnitt der Fülleitung 20 verbunden ist, und mit einem zweiten Eingang 32, der mit dem Hydrospeicher 21 verbunden ist. Ein Ausgang 33 des Wegeventils 30 ist in Abhängigkeit vom Lastdruck in der Arbeitsleitung 14 entweder mit dem Eingang 31 oder mit dem Eingang 32 verbindbar. Und zwar wirkt im Sinne einer Verbindung des Ausgangs 33 mit dem Eingang 32 eine einstellbare Druckfeder auf das nicht näher dargestellte Ventilglied des Ventils 30. Im Sinne einer Verbindung des Ausgangs 33 mit dem Eingang 31 wird das Ventilglied von dem Druck im Eingang 31, also vom Lastdruck der Hydrozylinder 12 beaufschlagt.Directional control valve with a first inlet 31, which is connected to the section of the filling line 20 between the working line 14 and the check valve 22, and with a second inlet 32, which is connected to the hydraulic accumulator 21. On Output 33 of the directional control valve 30 can be connected either to the input 31 or to the input 32, depending on the load pressure in the working line 14. In fact, in the sense of connecting the output 33 to the input 32, an adjustable compression spring acts on the valve member of the valve 30, which is not shown in detail. In the sense of connecting the output 33 to the input 31, the valve member is affected by the pressure in the input 31, that is, Load pressure of the hydraulic cylinder 12 is applied.
Auf das Wegeventil 30 ist ein Pilotventil 40 aufgesetzt, das als 2/2-Wege-Sitzventil ausgebildet ist und als entsperrbares Rückschlagventil betrachtet werden kann. Durch das Gehäuse des Pilotventils 40 hindurch führt ein vom Ausgang 33 des Wegeventils 30 ausgehender Steuerkanal 41 zu einem Anschluß P eines weiteren Pilotventils 50, das ein 4/2 -Wegeventil ist. Dessen Ventilglied nimmt unter der Wirkung einer Druckfeder 51 eine Ruhestellung ein, in der Durchgang zwischen dem Anschluß P und einem Anschluß A besteht, der mit einem Anschluß des Pilotventils 40 verbunden ist. Ein Tankanschluß T und ein weiterer An- Schluß B des Pilotventils 50 sind in dessen Ruhestellung abgesperrt. Der Tankanschluß ist über durch die Gehäuse der verschiedenen Ventile hindurchführende Kanäle mit einem Leckanschluß Y der Platte 26 verbunden. Der Anschluß B des Pilotventils 50 ist mit dem rückwärtigen Steuerraum eines zweiten sich in der Platte 26 befindlichen 2 -Wege-Einbauventils 60 verbunden, über das die kolbenstangenseitigen Druckräume 18 der Hydrozylinder 12 mit einem Tankanschluß T der Platte 26 verbunden werden können. Das Ventilglied des Pilotventils 50 kann von einem Elektromagneten 52 in eine Schaltstellung gebracht werden, in der der Anschluß P abgesperrt und die beiden Anschlüsse A und B mit dem Anschluß T verbunden sind.A pilot valve 40 is placed on the directional control valve 30, which is designed as a 2/2-way seat valve and can be regarded as an unlockable check valve. Through the housing of the pilot valve 40, a control channel 41 extending from the outlet 33 of the directional control valve 30 leads to a connection P of a further pilot valve 50, which is a 4/2 way valve. Whose valve member assumes a rest position under the action of a compression spring 51, in the passage between the port P and a port A, which is connected to a connection of the pilot valve 40. A tank connection T and a further connection B of the pilot valve 50 are blocked in its rest position. The tank connection is connected to a leakage connection Y of the plate 26 via channels leading through the housings of the various valves. The connection B of the pilot valve 50 is connected to the rear control chamber of a second 2-way built-in valve 60 located in the plate 26, via which the piston rod-side pressure chambers 18 of the hydraulic cylinders 12 can be connected to a tank connection T of the plate 26. The valve member of the pilot valve 50 can be brought into a switching position by an electromagnet 52, in which the port P is closed and the two ports A and B are connected to the port T.
Das Pilotventil 40 ist in einer Leitung 53 zwischen dem An- Schluß A des Pilotventils 50 und dem rückwärtigen Steuerraum 24 des Sperrventils 22 angeordnet. Sein Ventilglied wird von einer Druckfeder 42 und von dem im rückwärtigen Steuerraum des Sperrventils 22 herrschenden Druck in Richtung einer Ruhestellung beaufschlagt, in der es einen Abfluß von Druckmittel aus dem rückwärtigen Steuerraum 24 zum Anschluß A des Pilotventils 50 verhindert, einen Zufluß von Druckmittel vom Anschluß A des Pilotventils 50 zum rückwärtigen Steuerraum 24 aber zuläßt. Das Ventilglied kann von einem Elektromagneten 43 in eine Schaltstellung gebracht werden, in der ein freier Durchgang zwischen dem Anschluß A des Pilotventils 50 und dem rückwärtigen Steuerraum 24 des Sperrventils 22 besteht.The pilot valve 40 is arranged in a line 53 between the connection A of the pilot valve 50 and the rear control chamber 24 of the check valve 22. Its valve member is acted upon by a compression spring 42 and by the pressure prevailing in the rear control chamber of the check valve 22 in the direction of a rest position, in which it prevents an outflow of pressure medium from the rear control chamber 24 to port A of the pilot valve 50, an inflow of pressure medium from the port A of the pilot valve 50 to the rear control chamber 24, however, allows. The valve member can be brought by an electromagnet 43 into a switching position in which there is a free passage between the connection A of the pilot valve 50 and the rear control chamber 24 of the check valve 22.
Das Wegeventil 11 des Steuerblocks 10 ist hydraulisch proportional betätigbar, wobei die Vorsteuerdrücke mithilfe eines hy- draulischen Vorsteuergerätes 55 erzeugt und über Steuerleitungen 56 an das Wegeventil 11 gegeben werden. An die Vorsteuerleitung, in die ein Vorsteuerdruck eingesteuert wird, wenn die Hydrozylinder 12 in Richtung Heben des Auslegers betätigt werden sollen und dazu die bodenseitigen Druckräume 15 mit Druck- mittel beaufschlagt werden, ist ein elektrischer Druckschalter 57 angeschlossen, der bei einem bestimmten Vorsteuerdruck umschaltet. Dieser bestimmte Vorsteuerdruck ist vorzugsweise der Vorsteuerdruck, bei dem sich der federzentrierte Ventilschieber des Wegeventils 11 zu bewegen beginnt. Durch das Umschalten des Druckschalters 57 wird der Elektromagnet 43 des Pilotventils 40 erregt und dieses Pilotventil in die Schaltstellung gebracht, in der eine offene Verbindung zwischen dem Anschluß A des Pilotventils 50 und dem rückwärtigen Steuerraum 24 des Sperrven- tils 22 herrscht.The directional control valve 11 of the control block 10 can be actuated in a hydraulically proportional manner, the pilot control pressures being generated with the aid of a hydraulic pilot control device 55 and being supplied to the directional control valve 11 via control lines 56. An electrical pressure switch 57 is connected to the pilot line, into which a pilot pressure is introduced when the hydraulic cylinders 12 are to be actuated in the direction of lifting the boom and for this purpose pressure medium is applied to the bottom pressure chambers 15, which switches over at a specific pilot pressure. This specific pilot pressure is preferably the pilot pressure at which the spring-centered valve spool of the directional control valve 11 begins to move. By switching the Pressure switch 57 excites the electromagnet 43 of the pilot valve 40 and brings this pilot valve into the switch position in which there is an open connection between the connection A of the pilot valve 50 and the rear control chamber 24 of the shutoff valve 22.
Der Elektromagnet 52 des Pilotventils 50 wird willkürlich durch den Fahrzeugführer, wenn Nickschwingungen auftreten, oder automatisch bei einer bestimmten Geschwindigkeit der mobilen Ar- beitsmaschine, z.B. bei einer Geschwindigkeit von 6 km/Std. an Spannung gelegt.The solenoid 52 of the pilot valve 50 is activated arbitrarily by the driver when pitching vibrations occur, or automatically at a certain speed of the mobile working machine, e.g. at a speed of 6 km / h put on tension.
In der Ruhestellung des Wegeventils 11 steht in der Vorsteuerleitung 56, an die der Druckschalter 57 angeschlossen ist, kein Vorsteuerdruck an, so daß sich der Druckschalter 57 in seiner Ruhestellung befindet und der Elektromagnet 43 des Pilotventils 40 entregt ist. Das Pilotventil 40 nimmt deshalb die in der Figur 1 gezeigte Schaltstellung ein, in der ein Abfluß von Druckmittel aus dem rückwärtigen Steuerraum 24 des Sperrventils 22 verhindert ist. Sollte sich nun beim Einstechen der Ladeschaufel in Erdreich oder sonstiges Schüttgut in den Druckräumen 15 der Hydrozylinder 12 ein Druck aufbauen, so kann von diesem Druck das Sperrventil 22 nicht geöffnet werden, da ein Öffnen des Sperrventils nur möglich wäre, wenn Druckmittel aus dem Steuerraum 24 verdrängt würde. Der Hydrospeicher 21 wird deshalb in seinem Ladezustand durch den Druckaufbau in den Druckräumen 15 nicht beeinflußt. Gleiches gilt, wenn das Wegeventil in Richtung Senken der Hydrozylinder 12 betätigt wird. Auch dann bleibt das Pilotventil 40 in der gezeigten Schaltstellung, so daß das Sperrventil 22 nicht vom Druck in den Druckräumen 15 der Hydrozylinder 12 geöffnet werden kann.In the rest position of the directional valve 11, there is no pilot pressure in the pilot line 56, to which the pressure switch 57 is connected, so that the pressure switch 57 is in its rest position and the electromagnet 43 of the pilot valve 40 is de-energized. The pilot valve 40 therefore assumes the switch position shown in FIG. 1, in which an outflow of pressure medium from the rear control chamber 24 of the check valve 22 is prevented. If a pressure builds up in the pressure chambers 15 of the hydraulic cylinders 12 when the loading shovel is inserted into the soil or other bulk material, the check valve 22 cannot be opened from this pressure, since opening the check valve would only be possible if pressure medium from the control chamber 24 would be ousted. The hydraulic accumulator 21 is therefore not influenced in its state of charge by the pressure build-up in the pressure chambers 15. The same applies if the directional valve is actuated in the direction of lowering the hydraulic cylinder 12. The pilot valve 40 then remains in the switching position shown, so that the check valve 22 cannot be opened by the pressure in the pressure chambers 15 of the hydraulic cylinders 12.
Bei einer Betätigung des Wegeventils 11 in Richtung Heben dage- gen schaltet der Druckschalter 57 um, wodurch der Elektromagnet 43 betätigt wird und das Ventiglied des Pilotventils 40 in die zweite Schaltstellung gelangt. Solange der Druck in den Druckräumen 15 unterhalb des an der Druckfeder 34 des Wegeventils 30 eingestellten Drucks verbleibt, schaltet dieses den Speicher- druck über das Pilotventil 50 und das Pilotventil 40 zum rückwärtigen Steuerraum 24 des Sperrventils 22 durch. Der Lastdruck in den Druckräumen 15 der Hydrozylinder 12 öffnet nun das Sperrventil 22 immer dann, wenn er mindestens um die der Kraft der Druckfeder 25 äquivalente kleine Druckdifferenz über dem Speicherdruck liegt. Es kann dann Druckmittel in den Hydrospeicher gelangen, so daß dieser, sieht man einmal von der Kraft der schwachen Druckfeder 25 ab, immer auf den größten während eines Arbeitsspiels auftretenden Lastdruck in den Druckräumen 15 aufgeladen ist. Nur wenn der Lastdruck am Ventil 30 die Kraft der Druckfeder 34 zu überwinden vermag, bleibt das Sperrventil 22 geschlossen. Denn nach einer Umschaltung des Ventils 30 steht im rückwärtigen Steuerraum 24 des Sperrventils 22 der Lastdruck an, so daß im Verein mit der Druckfeder 25 das Sperrventil 22 sicher zugehalten wird. Der Druck im Hydrospeicher 21 kann deshalb den an der Druckfeder 34 des Ventils 30 eingestellten Wert nicht übersteigen. Aus Sicherheitsgründen ist jedoch zusätzlich ein Druckbegrenzungsventil 58 vorgesehen, dessen Eingang mit dem Hydrospeicher 21 verbunden ist. Es sei nun angenommen, daß die Ladeschaufel beladen und mit dem Radlader zu einer Abladesteile gefahren wird. Sobald dabei eine bestimmte Geschwindigkeit überschritten wird, werden beide Magnete 43 und 52 der Pilotventile 40 und 50 bestromt, so daß beide Pilotventile aus den in Figur 1 gezeigten Ruhestellungen in die andere Schaltstellung umschalten. Nun ist der rückwärtige Steuerraum 24 des Sperrventils 22 über das Pilotventil 40 und über das Pilotventil 50 mit dem Anschluß Y der Platte 26 verbunden und damit zum Tank 27 entlastet. Das Ventilglied 23 des Sperrventils 22 wird von Last- und Speicherdruck von seinem Sitz abgehoben, so daß eine offene Verbindung zwischen dem Hydrospeicher 21 und den Druckräumen 15 der Hydrozylinder 12 besteht. Da der Speicherdruck 21 dem während des Arbeitsspiels maximal erreichten Druck entspricht, erfolgt beim Öffnen des Sperrventils 22 kein Absacken, sondern allenfalls ein leichtes Anheben der Ladeschaufel. Es mag zwar sein, daß während des Arbeitsspiels Lastdrücke auftreten, die das Ventil 30 zum Schalten bringen und denen deshalb der Ladezustand des Hydrospeichers 21 nicht folgt. Diese Lastdrücke treten jedoch nur in be- sonderen Situationen, z.B. beim Losreißen eines im Erdreich verankerten Gegenstandes oder beim Fahren der Ladeschaufel gegen einen Anschlag auf, sind jedoch nicht durch das Gewicht der Ladeschaufel und des Ladegutes bedingt, das allein beim Fahren des Radladers wirkt. Der Ladezustand des Hydrospeichers 21 reicht deshalb immer, um die Ladeschaufel auf dem Niveau zu halten, die diese beim Öffnen des Sperrventils 22 einnimmt.On the other hand, when the directional valve 11 is actuated in the direction of lifting, the pressure switch 57 switches over, as a result of which the electromagnet 43 is actuated and the valve member of the pilot valve 40 reaches the second switching position. As long as the pressure in the pressure chambers 15 remains below the pressure set on the compression spring 34 of the directional control valve 30, this switches the accumulator pressure through via the pilot valve 50 and the pilot valve 40 to the rear control chamber 24 of the check valve 22. The load pressure in the pressure chambers 15 of the hydraulic cylinders 12 now opens the shut-off valve 22 whenever it is at least the small pressure difference equivalent to the force of the compression spring 25 above the storage pressure. Pressure medium can then get into the hydraulic accumulator so that, if one looks at the force of the weak compression spring 25, it is always charged to the greatest load pressure in the pressure chambers 15 that occurs during a working cycle. The check valve 22 remains closed only when the load pressure at the valve 30 can overcome the force of the compression spring 34. After a switchover of the valve 30, the load pressure is present in the rear control chamber 24 of the check valve 22, so that the check valve 22 is held securely in conjunction with the compression spring 25. The pressure in the hydraulic accumulator 21 can therefore not exceed the value set on the compression spring 34 of the valve 30. For safety reasons, however, a pressure limiting valve 58 is additionally provided, the input of which is connected to the hydraulic accumulator 21. It is now assumed that the loading shovel is loaded and driven to an unloading part by the wheel loader. As soon as a certain speed is exceeded, both magnets 43 and 52 of the pilot valves 40 and 50 are energized so that both pilot valves switch from the rest positions shown in FIG. 1 to the other switching position. Now the rear control chamber 24 of the check valve 22 is connected via the pilot valve 40 and via the pilot valve 50 to the connection Y of the plate 26 and is thus relieved to the tank 27. The valve member 23 of the check valve 22 is lifted from its seat by load and accumulator pressure, so that there is an open connection between the hydraulic accumulator 21 and the pressure chambers 15 of the hydraulic cylinders 12. Since the accumulator pressure 21 corresponds to the maximum pressure reached during the working cycle, when the shut-off valve 22 is opened there is no sagging, but rather a slight lifting of the loading shovel. It may be the case that load pressures occur during the working cycle which cause the valve 30 to switch and which therefore do not follow the state of charge of the hydraulic accumulator 21. However, these load pressures only occur in special situations, for example when an object anchored in the ground is torn away or when the loading shovel moves against a stop, but are not caused by the weight of the loading shovel and the load that only acts when the wheel loader is driving. The state of charge of the hydraulic accumulator 21 is therefore always sufficient to keep the loading shovel at the level which it assumes when the check valve 22 is opened.
Über das durch das Umschalten des Pilotventils 50 ebenfalls geöffnete Ventil 60 kann Druckmittel aus den kolbenstangenseiti- gen Druckräumen 18 der Hydrozylinder 12 in den Tank verdrängt oder aus dem Tank eingespeist werden, um Volumenveränderungen der Druckräume 18 auszugleichen, die während der offenen Verbindung der Druckräume 15 mit dem Hydrospeicher 21 auftreten.Via the valve 60, which is also opened by switching the pilot valve 50, pressure medium can be drawn from the piston rod side. gen pressure spaces 18 of the hydraulic cylinder 12 are displaced into the tank or fed from the tank to compensate for volume changes in the pressure spaces 18, which occur during the open connection of the pressure spaces 15 to the hydraulic accumulator 21.
Die Ausführung nach Figur 2 unterscheidet sich lediglich im Hinblick auf die Pilotventile 40 und 50 von derjenigen nach Figur 1. Es wird deshalb im Hinblick auf den Steuerblock 10, die Hydrozylinder 12, den Hydrospeicher 21, die Sperrventile 22 und 60, das Wegeventil 30 und das Vorsteuergerät 55 auf die entsprechende Beschreibung der Figur 1 verwiesen. Unterschiedlich zu der Ausführung nach Figur 1 ist, daß nun die beiden Pilotventile 40 und 50 zu einem einzigen Pilotventil 60 zusammengefaßt sind, das auf das Wegeventil 30 aufgesetzt ist. Das Pilot- ventil 60 besitzt eine federzentrierte Mittelstellung, in der die Anschlüsse T und B abgesperrt sind und zwischen den Anschlüssen P und A nur ein Durchfluß von P nach A möglich ist. Das Ventilglied des Pilotventils 60 kann durch Ansteuern eines Elektromagneten 52 aus der Mittelstellung heraus in eine seit- liehe Schaltstellung gebracht werden, in der die Anschlüsse A und B mit dem Anschluß T verbunden sind. Aus der Mittelstellung heraus in die Gegenrichtung kann das Ventilglied durch Beaufschlagung mit dem in der Vorsteuerleitung 56 herrschenden Druck verstellt werden, in der zum Zuführen von Druckmittel in die bodenseitigen Druckräume 15 der Hydrozylinder 12 ein Vorsteuerdruck aufgebaut wird. In dieser anderen Schaltstellung des Wegeventils 60 ist der Anschluß A frei mit dem Anschluß P verbunden. Der Anschluß A ist nun direkt mit dem rückwärtigen Steuerraum 24 des Sperrventils 22 verbunden. In der Mittelstellung oder in der Senkenstellung des Wegeventils 11 nimmt das Pilotventil 60 seine Mittelstellung ein, sofern die Geschwindigkeit der Arbeitsmaschine einen bestimmten Wert nicht überschreitet oder der Elektromagnet 52 nicht willkürlich eingeschaltet worden ist. In der Hebenstellung des Wegeventils 11 wird das Ventilglied des Wegeventils 60 mit Druck beaufschlagt und gelangt in die Schaltstellung, in der der Anschluß P mit dem Anschluß A verbunden ist. Im rückwärtigen Steuerraum 24 des Sperrventils 22 steht dann je nach Stellung des Ventils 30 der Speicherdruck oder der Lastdruck an. Der Hydrospeicher wird bis zum maximal erreichten Lastdruck bzw. bis zu dem an der Druckfeder 34 des Ventils 30 eingestellten Druck aufgeladen. Zur Dämpfung von Nickschwingungen während schneller Fahrt wird der Elektromagnet 52 erregt, so daß das Ventilglied des Wegeventils 60 in die Schaltstellung gelangt, in der die Anschlüsse A und B mit dem Anschluß T verbunden sind. Die rückwärtigen Steuerräume der Sperrventile 22 und 60 sind von Druck entlastet, so daß die beiden Sperrventile 22 und 60 öffnen und eine offene Verbindung zwischen dem Hydrospeicher 21 und den Druckräumen 15 der Hydrozylinder 12 besteht und aus den Druckräumen 18 Druckmittel verdrängt und in die Druckräume 18 Druckmittel eingespeist werden kann. Bei dieser Gelegenheit sei ausdrücklich darauf hingewiesen, daß der Druck am Anschluß T eines Ventilblocks üblicherweise einige bar über dem Tankdruck, der am Leckölanschluß Y herrscht, liegt, so daß das Sperrventil 60 von dem Druck am Tankanschluß T gegen den Tankdruck im rückwärtigen Steuerraum geöffnet werden kann. Besonders vorteilhaft ist, daß nach Verlangsamung der Fahrt und Entregung der Elektromagnete 43 und 52 bei der Ausführung nach Figur 1 und des Elektromagneten 52 allein bei der Ausführung nach Figur 2 wegen der Funktionsweise der Pilotventile 40 bzw. 60 als Rückschlagventile sofort Speicherdruck in den rückwärtigen Steuerraum 24 des Sperrventils 22 eingesteuert wird und deshalb das Sperrventil schließt. Eine Beeinflussung des Hydrospeichers 21 oder eine Einflußnahme durch den Hydrospeicher 21 auf die Steuerung ist dann bei einem anschließenden Senken der Hydrozylinder 12 oder einem Entladen der Schaufel, währenddessen sich das Wegeventil 11 in seiner Mittelstellung befindet, ausgeschlossen.The embodiment according to FIG. 2 differs from that according to FIG. 1 only with regard to the pilot valves 40 and 50. Therefore, with regard to the control block 10, the hydraulic cylinders 12, the hydraulic accumulator 21, the check valves 22 and 60, the directional control valve 30 and the pilot control unit 55 refers to the corresponding description of FIG. 1. Different from the embodiment according to FIG. 1 is that the two pilot valves 40 and 50 are now combined to form a single pilot valve 60 which is placed on the directional control valve 30. The pilot valve 60 has a spring-centered central position, in which the connections T and B are shut off and only a flow from P to A is possible between the connections P and A. The valve member of the pilot valve 60 can be brought out of the central position into a lateral switching position in which the connections A and B are connected to the connection T by driving an electromagnet 52. From the middle position in the opposite direction, the valve member can be adjusted by acting on the pressure prevailing in the pilot line 56, in which a pilot pressure is built up to supply pressure medium into the bottom-side pressure chambers 15 of the hydraulic cylinders 12. In this other switching position of the directional control valve 60, the connection A is freely connected to the connection P. The connection A is now connected directly to the rear control chamber 24 of the check valve 22. In the middle position or in the lower position of the directional control valve 11, the pilot valve 60 assumes its middle position provided the speed of the working machine does not exceed a certain value or the electromagnet 52 has not been switched on arbitrarily. In the raised position of the directional valve 11, the valve member of the directional valve 60 is pressurized and reaches the switch position in which the port P is connected to the port A. Depending on the position of the valve 30, the accumulator pressure or the load pressure is then present in the rear control chamber 24 of the check valve 22. The hydraulic accumulator is charged up to the maximum load pressure reached or up to the pressure set on the compression spring 34 of the valve 30. To dampen pitching vibrations during fast travel, the electromagnet 52 is excited so that the valve member of the directional control valve 60 reaches the switching position in which the connections A and B are connected to the connection T. The rear control chambers of the check valves 22 and 60 are relieved of pressure, so that the two check valves 22 and 60 open and there is an open connection between the hydraulic accumulator 21 and the pressure chambers 15 of the hydraulic cylinders 12 and displaces pressure medium from the pressure chambers 18 and into the pressure chambers 18 Pressure fluid can be fed. On this occasion, it should be expressly pointed out that the pressure at the connection T of a valve block is usually a few bar above the tank pressure prevailing at the drain port Y, so that the check valve 60 is opened by the pressure at the tank connection T against the tank pressure in the rear control chamber can. It is particularly advantageous that after slowing down and de-energization of the electromagnets 43 and 52 in the embodiment according to FIG. 1 and the electromagnet 52 alone in the embodiment according to FIG 24 of the check valve 22 is controlled and therefore closes the check valve. Influencing the hydraulic accumulator 21 or influencing the hydraulic accumulator 21 on the control system is then ruled out when the hydraulic cylinders 12 are subsequently lowered or the blade is unloaded, during which the directional control valve 11 is in its central position.
Bei der Ausführung nach Figur 3 zweigt die Fülleitung 20 vor dem Ventilsteuerblock 10 von einer Pumpenleitung 65 ab. In die zu mehreren Hydrospeichern 21 führende Fülleitung 20 sind, in Strömungsrichtung des Druckmittels von der Pumpenleitung 65 zu den Hydrozylindern 21 gesehen, zunächst ein 2/2 -Wegeventil 70, ein Druckregelventil 71 und ein Rückschlagventil 72 angeordnet. In der durch eine Druckfeder herbeigeführten Ruhestellung des Wegeventils 70 sind dessen beide Anschlüsse gegeneinander abgesperrt. Das Wegeventil kann durch Ansteuerung eines Elektromagneten 73 in eine DurchgangsStellung geschaltet werden. Und zwar wird der Elektromagnet 73 immer dann erregt, wenn das sich innerhalb des Steuerblocks 10 befindliche Wegeventil 11 zur AnSteuerung der Hydrozylinder 12 in Richtung Heben betätigt wird. In der Mittelstellung des Wegeventils 11 und bei dessen Betätigung in Richtung Senken befindet sich das Wegeventil 70 in seiner Ausgangsstellung. Am Druckregelventil 71 ist ein maximaler Druck eingestellt, bis zu dem die Hydrospeicher 21 aufgeladen werden können. Solange dieser Druck nicht erreicht ist, schaltet das Druckregelventil den Ausgang des Wegeventils 70 zum Rückschlagventil 72 durch. Bei Erreichen des Druckes wird der mit dem Ausgang des Wegeventils 70 verbundene Eingang des Ventils 71 gesperrt und der mit dem Rückschlag verbundene Anschluß mit Tank verbunden.In the embodiment according to FIG. 3, the filling line 20 branches off from a pump line 65 in front of the valve control block 10. A 2/2-way valve 70, a pressure control valve 71 and a check valve 72 are first arranged in the filling line 20 leading to a plurality of hydraulic accumulators 21, as seen in the flow direction of the pressure medium from the pump line 65 to the hydraulic cylinders 21. In the rest position of the directional valve 70, which is brought about by a compression spring, its two connections are shut off from one another. The directional control valve can be switched into a through position by driving an electromagnet 73. Namely, the electromagnet 73 is always energized when the directional valve 11 located within the control block 10 is actuated in the direction of lifting in order to actuate the hydraulic cylinders 12. In the middle position of the directional valve 11 and when it is actuated in the direction of lowering, the directional valve 70 is in its initial position. A maximum pressure is set at the pressure control valve 71, up to which the hydraulic accumulators 21 can be charged. As long as this pressure is not reached, the pressure control valve switches through the output of the directional valve 70 to the check valve 72. When the pressure is reached, the inlet of the valve 71 connected to the outlet of the directional control valve 70 is blocked and the connection connected to the check valve is connected to the tank.
Die Hydrospeicher 21 können über eine Leitung 74 mit der zwischen dem Arbeitsanschluß 13 des Wegeventils und den Druckräumen 15 der Hydrozylinder 12 verlaufenden Arbeitsleitung 14 verbunden werden. In diese Leitung 74 ist ein 4/2 -Wegeventil 75 eingebaut, das unter der Wirkung einer Druckfeder 76 eine Ruhe- Stellung einnimmt, in der zwei Abschnitte der Leitung 74 gegeneinander abgesperrt sind und somit keine Verbindung zwischen den Hydrospeichern 21 und der Arbeitsleitung 14 besteht. Außer den beiden für das Öffnen und Schließen der Leitung 74 notwendigen Anschlüsse besitzt das Wegeventil 75 zwei weitere An- Schlüsse für zwei Abschnitte einer Leitung 77, die von der Arbeitsleitung 15 zwischen dem Wegeventil 11 und den Druckräumen 18 der Hydrozylinder 12 zum Tank 27 führt. In der Ruhestellung des Wegeventils 75 sind auch die beiden Abschnitte der Leitung 77 gegeneinander abgesperrt. Das Wegeventil 75 kann von einem Elektromagneten 78 in eine Schaltstellung gebracht werden, in der jeweils die beiden Abschnitte der Leitung 74 und die beiden Abschnitte der Leitung 77 miteinander verbunden sind. Der Elektromagnet 78 wird erregt, wenn die mit der gezeigten hydraulischen Steueranordnung ausgestattete Arbeitsmaschine eine be- stimmte Fahrgeschwindigkeit überschreitet. Dann sind die Hydrospeicher 21 mit den Druckräumen 15 der Hydrozylinder 12 verbunden, so daß Nickschwingungen gedämpft werden können. Volumenveränderungen der Druckräume 18 können über die Leitung 77 aus- geglichen werden.The hydraulic accumulators 21 can be connected via a line 74 to the working line 14 running between the working connection 13 of the directional control valve and the pressure chambers 15 of the hydraulic cylinders 12. In this line 74, a 4/2 way valve 75 is installed, which, under the action of a compression spring 76, assumes a rest position in which two sections of the line 74 are shut off from one another and thus there is no connection between the hydraulic accumulators 21 and the working line 14 . In addition to the two connections necessary for opening and closing the line 74, the directional control valve 75 has two further connections for two sections of a line 77 which leads from the working line 15 between the directional control valve 11 and the pressure chambers 18 of the hydraulic cylinders 12 to the tank 27. In the rest position of the directional valve 75, the two sections of the line 77 are also shut off from one another. The directional control valve 75 can be brought into a switching position by an electromagnet 78, in which the two sections of the line 74 and the two sections of the line 77 are connected to one another. The electromagnet 78 is energized when the working machine equipped with the hydraulic control arrangement shown shows a agreed driving speed exceeds. Then the hydraulic accumulators 21 are connected to the pressure chambers 15 of the hydraulic cylinders 12, so that pitching vibrations can be damped. Changes in volume of the pressure chambers 18 can be compensated for via the line 77.
Da der Elektromagnet 73 des Wegeventils 70 nur erregt wird, wenn das Wegeventil 11 in Richtung Heben der Hydraulikzylinder 12 betätigt wird, wenn also den Druckräumen 15 Druckmittel zu- geführt wird, ist nur dann ein Aufladen der Hydrospeicher 21 möglich. Es kann z.B. nicht passieren, daß bei einem während schneller Fahrt der Arbeitsmaschine in der Leitung 65 anstehenden Druck über die Fülleitung 20 und das bei schneller Fahrt geschaltete Ventil 75 Druckmittel in die Druckräume 15 der Hy- drozylinder 12 gelangt, auch wenn sich das Wegeventil 11 inSince the electromagnet 73 of the directional control valve 70 is only energized when the directional control valve 11 is actuated in the direction of lifting the hydraulic cylinders 12, ie when pressure medium 15 is supplied to the pressure chambers, the hydraulic accumulators 21 can only be charged. For example, do not happen that when there is pressure in line 65 while the working machine is traveling fast, pressure medium enters pressure chambers 15 of hydraulic cylinders 12 via filling line 20 and valve 75 switched during fast travel, even if directional control valve 11 is in
Mittelstellung befindet und ein Ausfahren der Kolbenstangen der Hydrozylinder 12 nicht gewünscht ist. Middle position and extending the piston rods of the hydraulic cylinder 12 is not desired.

Claims

Patentansprüche claims
1. Hydraulische Steueranordnung für eine mobile Arbeitsmaschine, insbesondere für einen Radlader, mit mindestens einem Hydrozylinder (12), mit dessen Hilfe ein Arbeitswerkzeug bewegbar ist, mit einem Wegeventil (11) zur Steuerung der Druckmittelwege zwischen dem Hydrozylinder (12), einer Druckmittelquelle und einem Tank (27) , mit einem Hydrospeicher (21) , der über eine Fülleitung (20) mit der Druckmittelquelle verbindbar ist, und mit einem Steuerventil (50, 60, 75), mit dem eine Verbindung zwischen dem Hydrospeicher (21) und dem Hydrozylinder (12) auf- und zusteuerbar ist, dadurch gekennzeichnet, daß der Hydrospeicher (21) nur auffüllbar ist, wenn das Wegeventil (11) betätigt ist.1. Hydraulic control arrangement for a mobile working machine, in particular for a wheel loader, with at least one hydraulic cylinder (12), by means of which a working tool can be moved, with a directional control valve (11) for controlling the pressure medium paths between the hydraulic cylinder (12), a pressure medium source and a tank (27) with a hydraulic accumulator (21) which can be connected to the pressure medium source via a filling line (20), and with a control valve (50, 60, 75) with which a connection between the hydraulic accumulator (21) and the Hydraulic cylinder (12) can be opened and closed, characterized in that the hydraulic accumulator (21) can only be filled when the directional valve (11) is actuated.
2. Hydraulische Steueranordnung nach Anspruch 1, dadurch gekennzeichnet, daß das Wegeventil (11) aus einer mittleren Ruhestellung heraus nach zwei entgegengesetzten Richtungen in Arbeitsstellungen verstellbar ist und daß der Hydrospeicher (21) nur bei einer Betätigung des Wegeventils (11) in die eine Richtung auffüllbar ist.2. Hydraulic control arrangement according to claim 1, characterized in that the directional control valve (11) is adjustable from a middle rest position in two opposite directions in working positions and that the hydraulic accumulator (21) only when the directional control valve (11) is actuated in one direction is refillable.
3. Hydraulische Steueranordnung nach Anspruch 1 oder 2, gekennzeichnet durch ein Steuerventil (40, 60, 70), das durch eine Betätigung des Wegeventils (11) aus einer ersten Schalt- Stellung, in der es ein Befüllen des Hydrospeichers verhindert, in eine zweite Schaltstellung umschaltbar ist, in der der Hydrospeicher (21) befüllbar ist.3. Hydraulic control arrangement according to claim 1 or 2, characterized by a control valve (40, 60, 70) by actuating the directional valve (11) from a first switching position in which it prevents filling of the hydraulic accumulator, can be switched into a second switching position in which the hydraulic accumulator (21) can be filled.
4. Hydraulische Steueranordnung nach Anspruch 3, dadurch gekennzeichnet, daß das durch eine Betätigung des Wegeventils4. Hydraulic control arrangement according to claim 3, characterized in that by actuating the directional valve
(11) umschaltbare Steuerventil (40, 60) ein Sitzventil ist.(11) switchable control valve (40, 60) is a seat valve.
5. Hydraulische Steueranordnung nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß das Wegeventil (11) über ein mit Hilfe einer Vorsteuerung (55) vorgebbares Vorsteuersignal ansteuerbar ist und daß dem durch eine Betätigung des Wegeventils (11) umschaltbaren Steuerventil (40, 60, 70) beim Vorliegen eines Vorsteuersignals für das Wegeventil (11) ein Steuersignal zur Umschaltung von der ersten Schaltstellung in die zweite Schaltstellung zuführbar ist.5. Hydraulic control arrangement according to claim 3 or 4, characterized in that the directional control valve (11) can be controlled via a pilot control signal which can be predetermined by means of a pilot control (55) and that the control valve (40, 60,) which can be switched over by actuating the directional control valve (11) 70) when a pilot signal for the directional control valve (11) is present, a control signal for switching over from the first switching position into the second switching position can be supplied.
6. Hydraulische Steueranordnung nach einem vorhergehenden Anspruch, dadurch gekennzeichnet, daß die Fülleitung (20) von einer zwischen dem Wegeventil (11) und dem Hydrozylinder (12) verlaufenden Arbeitsleitung (14) abzweigt, daß in der Fülleitung (20) ein druckgesteuertes Sperrventil (22) mit einem Ventilglied (23) angeordnet ist, das vom in der Arbeitsleitung (14) herrschenden Lastdruck in Öffnungsrichtung und vom Druck in einem rückwärtigen Steuerraum (24) in Schließ- richtung beaufschlagbar ist, und daß der rückwärtige Steuerraum (24) zum Befüllen des Hydrospeichers (21) mit dem Hydrospeicher (21) und zum Öffnen der Verbindung zwischen dem Hydrospeicher (21) und dem Hydrozylin- der (12) mit Tank (27) verbindbar und bei nicht betätigtem Wegeventil (11) gegen den Abfluß von Druckmittel absperrbar ist.6. Hydraulic control arrangement according to one of the preceding claims, characterized in that the filling line (20) branches off from a working line (14) running between the directional control valve (11) and the hydraulic cylinder (12), that in the filling line (20) a pressure-controlled check valve ( 22) is arranged with a valve member (23) which can be acted upon by the load pressure prevailing in the working line (14) in the opening direction and by the pressure in a rear control chamber (24) in the closing direction, and that the rear control chamber (24) for filling of the hydraulic accumulator (21) with the hydraulic accumulator (21) and for opening the connection between the hydraulic accumulator (21) and the hydrocycline the (12) can be connected to the tank (27) and can be blocked against the outflow of pressure medium when the directional control valve (11) is not actuated.
7. Hydraulische Steueranordnung nach Anspruch 6, dadurch gekennzeichnet, daß der rückwärtige Steuerraum (24) des Sperrventils (22) bei nicht betätigtem Wegeventil (11) über ein zum Steuerraum (24) hin öffnendes Rückschlagventil (40, 60) vom Hydrospeicher (21) her mit Druckmittel beaufschlagbar ist.7. Hydraulic control arrangement according to claim 6, characterized in that the rear control chamber (24) of the check valve (22) when the directional valve (11) is not actuated via a check valve (40) opening towards the control chamber (24) from the hydraulic accumulator (21). pressure fluid can be applied here.
8. Hydraulische Steueranordnung nach Anspruch 6 oder 7, gekennzeichnet durch ein Pilotventil (60) , durch das in einer Mittelstellung der rückwärtige Steuerraum (24) des Sperrventils (22) gegen den Abfluß von Druckmittel abgesperrt ist, das aus der Mittelstellung in eine erste seitliche Schaltstellung ver- stellbar ist, in der der rückwärtige Steuerraum (24) zum Tank (27) entlastet ist, und das durch eine Betätigung des Wegeventils (11) aus der Mittelstellung in eine zweite seitliche Schaltstellung verstellbar ist, in der der rückwärtige Steuerraum (24) mit Speicherdruck beaufschlagbar ist.8. Hydraulic control arrangement according to claim 6 or 7, characterized by a pilot valve (60) by which in a central position of the rear control chamber (24) of the check valve (22) is blocked against the outflow of pressure medium, which from the central position into a first lateral Switch position is adjustable, in which the rear control chamber (24) is relieved to the tank (27), and which can be adjusted by actuating the directional valve (11) from the middle position into a second side switch position, in which the rear control chamber (24 ) can be acted upon with storage pressure.
9. Hydraulische Steueranordnung nach Anspruch 6 oder 7, gekennzeichnet durch ein erstes Pilotventil (50) mit einer Schaltstellung, in der der rückwärtige Steuerraum (24) des Sperrventils (22) zum Tank (27) entlastbar ist, und mit einer Schaltstellung, in der der rückwärtige Steuerraum (24) mit9. Hydraulic control arrangement according to claim 6 or 7, characterized by a first pilot valve (50) with a switching position in which the rear control chamber (24) of the check valve (22) to the tank (27) can be relieved, and with a switching position in which the rear control room (24) with
Speicherdruck (21) beaufschlagbar ist, und durch ein zweites Pilotventil (40) , das im vom rückwärtigen Steuerraum (24) zum ersten Pilotventil (50) verlaufenden Druckmittelkanal (53) angeordnet ist und eine Schaltstellung, in der der Druckmittelka- nal (53) gegen einen Abfluß von Druckmittel aus dem rückwärtigen Steuerraum (24) abgesperrt ist, und eine Schaltstellung, in der der Druckmittelkanal (53) offen ist, aufweist.Storage pressure (21) can be acted upon, and by a second pilot valve (40) which is arranged in the pressure medium channel (53) running from the rear control chamber (24) to the first pilot valve (50) and a switching position in which the pressure medium nal (53) is blocked against an outflow of pressure medium from the rear control chamber (24), and has a switching position in which the pressure medium channel (53) is open.
10. Hydraulische Steueranordnung nach Anspruch 9, dadurch gekennzeichnet, daß die beiden Pilotventile (40, 50) jeweils durch einen Elektromagneten (43, 52) betätigbar sind. 10. Hydraulic control arrangement according to claim 9, characterized in that the two pilot valves (40, 50) are each actuated by an electromagnet (43, 52).
EP98916979A 1997-03-21 1998-03-17 Hydraulic control system for a mobile work machine, especially a wheel loader Expired - Lifetime EP0968334B1 (en)

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DE19711769A DE19711769C2 (en) 1997-03-21 1997-03-21 Hydraulic control arrangement for a mobile work machine, in particular for a wheel loader
DE19711769 1997-03-21
PCT/EP1998/001543 WO1998042923A1 (en) 1997-03-21 1998-03-17 Hydraulic control system for a mobile work machine, especially a wheel loader

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EP0968334B1 EP0968334B1 (en) 2002-06-12

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Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3796376B2 (en) * 1999-02-22 2006-07-12 カヤバ工業株式会社 Control device for work vehicle
US6634653B2 (en) * 2001-07-17 2003-10-21 Probir Chatterjea & Associates, Inc. Ride control system for construction equipment
DE10148962C1 (en) * 2001-10-04 2003-02-27 Hydac Technology Gmbh Hydraulic control device for digger or excavator has control block controlling switching valve in filling line and controlled valve in bypass line damping movement of hydraulic cylinders
US6612375B2 (en) * 2001-11-02 2003-09-02 Husco International, Inc. Apparatus for counteracting vehicle pitch variation resulting from the operation of an electronic draft control system
GB2418903B (en) * 2004-10-08 2008-06-25 Caterpillar Inc Ride control circuit for a work machine
US7661251B1 (en) * 2008-08-22 2010-02-16 Deere & Company Header float system for use with an agricultural windrower or combine
US7793740B2 (en) 2008-10-31 2010-09-14 Caterpillar Inc Ride control for motor graders
KR101021773B1 (en) 2009-04-06 2011-03-15 울산대학교 산학협력단 Direct drive hydro-static actuator
CN102587444B (en) * 2012-03-07 2014-07-30 浙江大学 Oil hybrid system for excavator with energy differential recovery
CN102691700B (en) * 2012-06-20 2014-12-03 山河智能装备股份有限公司 Boarding rotating energy recycling system
CN102995523A (en) * 2012-09-07 2013-03-27 徐州万邦道路工程装备服务股份公司 Hydraulic control device of ironing plate of paver
CN103243752B (en) * 2013-05-07 2015-09-02 山东理工大学 Stage clip energy storage type loading arm potential energy reclaiming device
CN103243751B (en) * 2013-05-07 2015-09-02 山东理工大学 Elastic rubber belt energy accumulator formula loading arm potential energy reclaiming device
CN103225321A (en) * 2013-05-07 2013-07-31 山东理工大学 Elastic rubber band energy-stored type loading machine movable arm potential energy recycle and regeneration control method
CN103243750B (en) * 2013-05-07 2015-11-18 山东理工大学 Composite accumulator formula loading arm potential energy reclaiming device
CN103243753A (en) * 2013-05-07 2013-08-14 山东理工大学 Elastic rubber band energy accumulator type loader movable arm potential energy recovery and regeneration control system
CN105421509B (en) * 2015-11-16 2017-11-10 潍柴动力股份有限公司 A kind of hybrid excavator movable arm potential energy retracting device and hybrid excavator
US10246854B2 (en) 2016-10-26 2019-04-02 Wacker Neuson Production Americas Llc Material handling machine with ride control system and method
CN108757593B (en) * 2018-06-12 2020-11-10 北京理工大学 Hydraulic oil supply system of machine tool for rolling and strengthening torsion shaft tooth root
RU2719295C9 (en) * 2019-06-18 2020-09-03 Федеральное государственное бюджетное образовательное учреждение высшего образования " Псковский государственный университет" Continuous-action excavating machine hydraulic drive
JP7214610B2 (en) * 2019-10-28 2023-01-30 株式会社クボタ Hydraulic system of work equipment
RU2768769C1 (en) * 2021-03-26 2022-03-24 Федеральное государственное бюджетное образовательное учреждение высшего образования «Псковский государственный университет» Trencher

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3717995A (en) * 1971-10-12 1973-02-27 Hesston Corp Hydraulic flotation for implement header
US3971215A (en) * 1974-06-06 1976-07-27 Marion Power Shovel Company, Inc. Power shovel and crowd system therefor
JPH0663264B2 (en) 1984-07-20 1994-08-22 株式会社小松製作所 Swing energy recovery and reuse device for swiveling construction machinery
JPS63106404A (en) 1986-10-22 1988-05-11 Komatsu Ltd Hydraulic device for driving inertial body
JPS6466324A (en) * 1987-09-08 1989-03-13 Kobe Steel Ltd Vibration suppressor for vehicular construction machine
US5116188A (en) * 1987-09-16 1992-05-26 Kabushiki Kaisha Kobe Seiko Sho Vibration suppressing device for wheeled construction equipment
JP2688966B2 (en) 1989-01-13 1997-12-10 油谷重工株式会社 Running vibration suppression and stabilization circuit for wheeled construction machines
EP0381788B1 (en) * 1989-02-06 1994-10-19 KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. Vibration suppressing device for a wheeled construction equipment
DE3909205C1 (en) * 1989-03-21 1990-05-23 Hanomag Ag, 3000 Hannover, De
JPH0662270B2 (en) * 1989-05-10 1994-08-17 株式会社神戸製鋼所 Displacement restraint device for mobile crane
JP2602728B2 (en) * 1990-03-31 1997-04-23 東洋運搬機株式会社 Vehicle dynamic damper
JP2582310B2 (en) 1990-09-10 1997-02-19 株式会社小松製作所 Potential energy recovery and utilization device for work equipment
US5195864A (en) * 1991-08-28 1993-03-23 Case Corporation Hydraulic system for a wheel loader
DE4221943C2 (en) * 1991-09-04 1996-01-25 Orenstein & Koppel Ag Hydraulic system for mobile working machines provided with working devices
DE9208942U1 (en) * 1991-09-04 1993-01-14 O & K Orenstein & Koppel Ag, 1000 Berlin, De
DE4129509C2 (en) * 1991-09-05 1994-06-16 Rexroth Mannesmann Gmbh Hydraulic control arrangement for construction machines
SK368091A3 (en) * 1991-12-04 1994-05-11 Frantisek Krnavek Device for potential energy recuperation of working device of building or earth machine
JP3129495B2 (en) 1991-12-13 2001-01-29 株式会社小松製作所 Potential energy recovery device for lifting machine
JP3153864B2 (en) * 1993-03-29 2001-04-09 株式会社小松製作所 Running vibration suppression device for wheel type construction vehicles
JPH06286446A (en) 1993-03-30 1994-10-11 Hitachi Constr Mach Co Ltd Suspension control device for vehicular construction machine
DE4416228A1 (en) * 1994-05-07 1995-11-09 Rexroth Mannesmann Gmbh Hydraulic system for a mobile working device, in particular for a wheel loader
US5992146A (en) * 1996-04-12 1999-11-30 Caterpillar Inc. Variable rate ride control system
US6167701B1 (en) * 1998-07-06 2001-01-02 Caterpillar Inc. Variable rate ride control

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9842923A1 *

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KR100491841B1 (en) 2005-05-27
DE59804420D1 (en) 2002-07-18
JP2001519009A (en) 2001-10-16
DE19711769A1 (en) 1998-10-01
DE19711769C2 (en) 1999-06-02
WO1998042923A1 (en) 1998-10-01
KR20010005508A (en) 2001-01-15
EP0968334B1 (en) 2002-06-12

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