Classifications

• • 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
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
  • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
  • F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
  • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
  • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
  • B66F9/075—Constructional features or details
  • B66F9/20—Means for actuating or controlling masts, platforms, or forks
  • B66F9/22—Hydraulic devices or systems
• • 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
  • E02F9/2278—Hydraulic circuits
  • E02F9/2296—Systems with a variable displacement pump
• • 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
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/205—Systems with pumps
  • F15B2211/2053—Type of pump
  • F15B2211/20546—Type of pump variable capacity
  • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
  • F15B2211/212—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being accumulators
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/305—Directional control characterised by the type of valves
  • F15B2211/30505—Non-return valves, i.e. check valves
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/305—Directional control characterised by the type of valves
  • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
  • F15B2211/3053—In combination with a pressure compensating valve
  • F15B2211/30555—Inlet and outlet of the pressure compensating valve being connected to the directional control valve
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/31—Directional control characterised by the positions of the valve element
  • F15B2211/3105—Neutral or centre positions
  • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/32—Directional control characterised by the type of actuation
  • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/35—Directional control combined with flow control
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/40—Flow control
  • F15B2211/405—Flow control characterised by the type of flow control means or valve
  • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/50—Pressure control
  • F15B2211/505—Pressure control characterised by the type of pressure control means
  • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
  • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/50—Pressure control
  • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
• • 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
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
  • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
  • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
  • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel

Definitions

• the invention is based on a load-sensing hydraulic control arrangement, which is used in particular for a wheel loader or a forklift.
• a load-sensing hydraulic control arrangement is known, for example, from EP 0 566 449 A1.
• An adjusting pump is set depending on the highest load pressure of the hydraulic consumers actuated so that the pump pressure is above the highest load pressure by a certain pressure difference.
• Pressure fluid flows to each hydraulic consumer via an adjustable metering orifice.
• Each metering orifice is followed by a pressure compensator, which ensures that if the quantity of pressure medium supplied is sufficient, there is a certain pressure difference across the respective metering orifice regardless of the load pressures of the hydraulic consumers, so that the quantity of pressure medium flowing to a hydraulic consumer only depends on the opening cross section of the respective metering orifice.
• the variable pump is adjusted so that it delivers the required amount of pressure medium.
• the pressure compensators are connected downstream of the metering orifices and are acted upon in the opening direction by the pressure after the respective metering orifice and in the closing direction by a control pressure present in a rear control chamber, which usually corresponds to the highest load pressure of all hydraulic consumers supplied by the same hydraulic pump.
• LUDV control load-independent flow distribution
• Hydraulic consumers controlled in this way are called LUDV consumers for short.
• a LUDV control is a special case of a load-sensing or load-sensing control (LS control).
• Wheel loaders or forklifts and similar mobile work machines tend to pitch when they drive faster.
• a damping system which is part of the hydraulic control arrangement of the wheel loader.
• the generally two hydraulic lift cylinders for lifting and lowering the loading shovel can be connected to a hydraulic accumulator via a shut-off valve, which is provided by a hydraulic pump via a filling line the directional valve control block branches off from the pump line and in which a filling valve can be charged.
• the filling valve closes when a limit pressure is reached in the hydraulic accumulator.
• the 5 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.
• pressure medium can flow freely back and forth between the lift cylinders and the hydraulic accumulator, so that the loading shovel is no longer rigidly connected to the vehicle body and the pitching vibrations are damped.
• the branching of the filling line in front of the directional control valve block 15 entails that the hydraulic accumulator is charged not only when the directional valve assigned to the lift cylinders is actuated, but 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 0. If the check valve is then opened, the lift cylinders can move in an uncontrolled manner.
• a control arrangement for damping pitching vibrations is also known from DE 39 09 205 C1, in which the filling line branches off from the consumer line between the directional control valve block and the lift cylinders.
• the hydraulic components for pitching vibration damping are part of a so-called throttle control of the hydraulic consumers.
• the directional control valves have a so-called circulation channel through which the pump conveys pressure medium in circulation to the tank when no directional control valve is actuated.
• the aim of the invention is to arrange the known hydraulic Komis components for pitching vibration damping of a mobile machine within a load-sensing hydraulic control arrangement so that the uncontrolled movements of the hydraulic cylinders described above are largely avoided.
• the filling line branches off from the intermediate section of the main line in a load-sensing hydraulic control arrangement. If the directional control valve is not actuated and the metering orifice is also closed, this intermediate section is fluidly connected neither directly to the hydraulic consumer nor to the pressure medium source. 5 Therefore, if the directional control valve is not actuated, neither the load pressure nor the inlet pressure has a direct influence on the accumulator pressure. At most, if a certain state is maintained for a longer period of time, the state of charge of the memory may be changed via internal leakages. However, this is rare because the operating state changes continuously during the operation of a mobile machine.
• the filling valve closes the filling line when the storage pressure reaches a certain value.
• the full valve should have a large opening cross-section for the pressure medium flowing into the hydraulic accumulator and must therefore be dimensioned accordingly large, so that a spring that acts on the full valve piston in the opening direction of the full valve and its pretensioning force the closing pressure determined by which the full valve is closed, does not have to have a size leading to a voluminous full valve, it is provided according to claim 7 that the full valve piston on a measuring surface which is significantly smaller than the cross section of the valve bore receiving the full valve piston, from the closing pressure in the closing direction How such a small measuring surface can be created in an advantageous manner is specified in claims 8 and 9
• the shut-off valve between the hydraulic accumulator and the pressure chamber of the hydraulic cylinder should also have a large opening cross-section. It is therefore pilot-controlled by a pilot valve and has a control surface which is relieved of pressure in one switching position of the pilot valve and in a second switching position of the pilot valve a closing pressure acting in the closing direction is applied
• the embodiment according to claim 16 also appears to be particularly advantageous, according to which the shut-off valve and full valve are combined to form a single control valve having a control piston, which has a storage connection connected to the hydraulic accumulator, a consumer connection connected to the consumer section of the main line and a full connection connected to the intermediate section of the main line and has three valve positions, wherein in a first valve position taken up under the action of a valve spring, the hydraulic accumulator can be filled with pressure medium via the full connection and the accumulator connection, in a second valve position into which the control valve arrives when the storage pressure or the consumer pressure reaches a certain level, all three connections are blocked against each other and in the third valve position, the consumer connection and the storage connection are connected to one another.
• FIG. 1 shows the first exemplary embodiment, in which the filling valve and the blocking valve are separate valves, the filling valve is controlled by the pressure at its inlet and the blocking valve is a logic element with three control surfaces
• FIG. 2 shows the second exemplary embodiment, in which the filling valve and blocking valve are in turn separated from one another, wherein the filling valve is a pressure reducing valve and the shut-off valve is formed by two oppositely connected lockable check valves
• Figure 3 shows the third embodiment, in which the filling valve and shut-off valve are combined into a single control valve
• Figure 4 shows a fourth embodiment, in which the filling valve again as
• FIG. 5 shows a fifth embodiment which differs from that according to FIG. 4 only in that the inlet and outlet of the filling valve are interchanged and thereby the full valve piston is controlled by the pressure at the inlet
• FIG. 6 shows a longitudinal section through the respective fill valve of FIGS. 4 and 5.
• the various valves for controlling the hydraulic consumers of a wheel loader are combined to form a control block 10, which comprises a plurality of directional valve sections 11, 12 and 13 in disk or monoblock construction. Only the directional valve section 11, which serves to control two lift cylinders 14 5, is shown in detail in the circuit diagram.
• the directional valve section contains a directional valve 15, which can be operated proportionally with the aid of two pilot valves 16 and 17 which can be controlled by proportional magnets and which are designed as pressure-reducing valves.An adjustable metering orifice 18 is also integrated into the directional valve, the opening cross-section of which is one in a through the displacement path
• the directional control valve 15 has an inlet connection 19, to which an inlet channel 20 leading from a connection P of the control block 10 leads.
• a tank chamber 21 is connected to a tank channel 22 leading through the block 10.
• a first consumer chamber 23 of the directional control valve 15 has a first consumer connection 24 and one
• second consumer chamber 25 connected to a second consumer port 26 of the directional valve section 1 1.
• a consumer line 27 leads from the consumer connection 24 to the pressure chambers 28 on the bottom and a consumer line 29 leads from the consumer connection 26 to the pressure chambers 30 on the rod side of the two lift cylinders 14.
• the metering orifice 18 is located between the inlet chamber 19 and a first intermediate chamber 35 the input of a pressure compensator 36 is connected, from the output of which a channel leads via a load holding valve 37 to a second intermediate chamber 38 of the directional control valve 15.
• the control piston of the pressure compensator 36 is pressurized in the direction of closing the connection between the inlet and the outlet of the pressure compensator by the pressure in a load signaling line 39, which corresponds to the highest load pressure of all hydraulic consumers of the wheel loader actuated at the same time.
• a weak compression spring 40 also acts in the closing direction.
• the control piston of the pressure compensator 36 is acted upon by the pressure at the inlet of the pressure compensator.
• the highest load pressure is also applied to a controller of the adjustable hy dropumpe 9 reported, which in each case conveys so much pressure medium that there is an inlet pressure in the inlet line 20 which is above the highest load pressure by a certain pressure difference of, for example, 20 bar.
• I O cher Vogel 27 to the pressure chambers 28 of the two lift cylinders 14. From the pressure chambers 30, pressure medium is displaced into the tank channel 22 via the consumer line 29, the consumer connection 26, the consumer chamber 25 and the tank chamber 21. As described, the pressure medium first flows over the metering orifice 18 and then over the pressure compensator 36.
• the pressure compensator 36 throttles the flowing pressure medium so strongly that the pressure at its input to the control piston generates such a force acting in the opening direction that the sum of the force generated by the load pressure and the force of the spring 40 is kept in balance.
• the pressure compensator is almost completely open if the lift cylinders are operated alone or have the highest load pressure. If this is, for example, 100 bar and the force of the compression spring 40 is 0.5 bar equivalent, a pressure of 100.5 bar builds up at the inlet of the pressure compensator 36.
• the inlet pressure is 120 bar, so that there is a pressure difference of 19.5 bar via the metering orifice.
• the load pressure of the lift cylinder 14 is, for example, only 50 bar and the load pressure of another hydraulic consumer actuated simultaneously, for example 120 bar, 36 120.5 bar act in the closing direction of the pressure compensator.
• a balance of forces on the control piston therefore only exists when 120.5 bar is also present at the inlet of the pressure compensator.
• the control piston closes the opening cross-section of the pressure compensator accordingly.
• the inlet pressure is now 140 bar that there is again a pressure difference of 19.5 bar via the metering orifice 18.
• the 120.5 bar drops to the load pressure of the lift cylinder of 50 bar via the pressure compensator.
• the channels and lines through which pressure medium flows from the variable displacement pump 9 to the pressure chambers 28 or to the pressure chambers 30 of the lift cylinder 14 may be referred to as the main line.
• the section of this main line between the variable displacement pump 9 and the inlet chamber 19 of the directional control valve 15 is the inlet section.
• I O pressure chambers 28 or between the consumer chamber 25 and the pressure chambers 30 of the lift cylinder is the consumer section.
• the control arrangement has a hydraulic damping system for damping pitching vibrations of the wheel loader.
• Essential elements of this damping system are one or more hydraulic accumulators 40, a filling valve 42 and a shut-off valve 50.
• the full valve 42 is a pilot-operated 3/2-way valve, which is arranged in a filling line 41, which is between the load holding valve 37 and the intermediate chamber 38
• Directional control valve 17 goes from the intermediate section of the main line. From this, pressure medium can flow into the hydraulic accumulator 40 via the first section of the filling line 41, the said inlet of the filling valve 42, its outlet and via a check valve 43, which blocks the outlet of the filling valve 42, in order to adjust the hydraulic accumulator to the load pressure to load the lift cylinder 14.
• the check valve 43 prevents the pressure in the hydraulic accumulator 40 from dropping during an operating cycle with the lift cylinders 14.
• the hydraulic accumulator 40 is therefore at the highest in the pressure chambers of the lift cylinders 14 charged load pressure occurring during a work cycle. This applies up to a maximum load pressure, which is determined by the biasing force of a spring on the pilot valve of the filling valve 42.
• This pilot valve opens as soon as this maximum load pressure to be transferred to the accumulator is reached 5. This is indicated by the control line 47 leading from the mentioned input of the filling valve 42 to a control side.
• the pilot valve of the filling valve responds and the filling valve switches to its second switching position. In this the entrance is blocked off. The output is relieved to the tank, so that it is ensured that no pressure medium IO gets into the hydraulic accumulator 40.
• a pressure relief valve 60 is additionally provided.
• a compensating line 44 in which the check valve 50 is located.
• This is structured like a logic element. Such has two connections, which can be shut off from one another like a poppet valve, as well as different control surfaces on which different pressures can act.
• the load pressure prevailing in the pressure chambers 28 0 of the lift cylinder 14 acts on a first control surface 51 in the opening direction of the valve.
• the accumulator pressure acts in the opening direction on a second control surface 52.
• a weak spring 56 acts in the closing direction of the valve, due to which the movable valve element of the blocking valve 50 assumes a closed rest position when the pressure forces cancel each other out.
• a third control surface 53 of the check valve 50 is exactly the same size as the control surfaces 51 and 52 taken together.
• the highest of the two pressures load pressure and storage pressure is present on the control surface 53, or the control surface 53 is relieved of pressure towards a leakage line 46.
• the highest of the two pressures load pressure and storage pressure is selected by a shuttle valve 55.
• the pilot valve 54 While working with the lift cylinders 14, the pilot valve 54 assumes the rest position shown in FIG. 5, in which the control surface 53 is loaded with pressure.
• the check valve 50 is in its locked position. If the mobile working machine exceeds a certain driving speed or if the driver operates an electrical switch at will, the solenoid of the pilot valve 54 is energized so that it reaches its second switching position I O, in which the control surface 53 is relieved of pressure. Under the effect of the accumulator pressure and the load pressure, the check valve 50 reaches its second position, in which there is a wide-open connection between the pressure chambers 28 of the lift cylinders 14 and the hydraulic accumulator 40. Pressure medium can be displaced from the pressure spaces 28 to the reservoir 40. Conversely, pressure medium can flow from the reservoir 40 into the pressure spaces 28.
• the loading shovel of the wheel loader carried by the lift cylinders 14 is no longer firmly connected to the vehicle body, so that pitching vibrations are damped.
• Another logic element 58 with a pilot valve 59 is arranged between the pressure spaces 30 of the lift cylinders 14 and the tank channel 22.
• the pilot valve 59 is in the rest position shown in FIG. 1, in which the logic element 58 is closed.
• the electromagnet of the pilot valve 59 is energized simultaneously with the electromagnet of the pilot valve 54 of the check valve 50, so that a 5 control chamber on the logic element 58 is relieved of pressure and the logic element is already released from a low pressure in the pressure chambers 30 of the lift cylinder 14 can be opened.
• pressure medium can be displaced from the pressure spaces 30 via the logic element 58 into the tank channel 22.
• Pressure medium from the tank channel 22 are sucked into the pressure chambers 30 via the logic element 58.
• a pilot-controlled pressure reducing valve 65 is arranged as the filling valve, which is controlled by the pressure at its outlet on the storage side becomes. So it closes when the accumulator pressure reaches a maximum value.
• the check valve 43 is arranged in the embodiment according to FIG. 2 between the filling valve and the intermediate section of the main line. It fulfills the same function as in the embodiment according to FIG. 1.
• Two lockable check valves 67 are used as the check valve, which is now provided with the reference number 66 and which are arranged a ⁇ -parallel in the compensation line 44 running between the hydraulic accumulator 40 and the pressure chambers 28.
• the two check valves 67 are pilot-controlled by a pilot valve 68, which can assume two switching positions and has four connections. One of these is cordoned off.
• a connection is connected to the leakage line 46.
• a second connection is located at the outlet of the shuttle valve 55 which is also present in the embodiment according to FIG. 1 and which selects the highest of the two pressures load pressure in the pressure chambers 28 of the lift cylinders 14 and accumulator pressure.
• the fourth port of the pilot valve 68 is connected to the control chambers of the check valves 67.
• the pilot valve 68 Under the action of a compression spring, the pilot valve 68 assumes a rest position in which the control chambers of the check valves 67 are relieved of pressure towards the leakage line 46. One non-return valve 67 can therefore flow through pressure medium 28 from the other non-return valve 67 from the hydraulic accumulator 40. There is an open connection between the pressure chambers 28 and the hydraulic accumulator 40. The system for damping pitching vibrations is then switched on. If the pilot valve 68 is brought into its second switching position by energizing an electromagnet, in which the control chambers of the two check valves 67 are acted upon by the highest of the two pressures, load pressure and storage pressure, which is selected via the shuttle valve 55. The check valves 67 are then blocked.
• the logic element 58 with pilot valve 59 and the pressure limiting valve 60 are also present in the embodiment according to FIG.
• the embodiment according to FIG. 2 works in principle exactly the same as that according to FIG. 1, so that reference can be made here to the corresponding description of the first embodiment.
• valve 3 also corresponds with regard to the directional control valve 15, the pressure compensator 36, the load holding valve 37, the logic element 58 together with the pilot valve 59 and the pressure limiting valve 60 to the embodiment according to FIG. 1.
• the shut-off valve and the filling valve are now combined to form a single control valve 70, the check valve 43 in the filling line also
• the control valve 70 has three connections, namely a filling connection 71, which is connected via the filling line 41 between the load-holding valve 37 and the intermediate chamber 38 of the directional control valve 15 to the intermediate section of the main line, a consumer connection 72, which via the equalization line 44 with the pressure chambers 28 of the Lift cylinder 14 is connected and a storage connection 73 which is connected to the hydraulic accumulator 40.
• a filling connection 71 which is connected via the filling line 41 between the load-holding valve 37 and the intermediate chamber 38 of the directional control valve 15 to the intermediate section of the main line
• a consumer connection 72 which via the equalization line 44 with the pressure chambers 28 of the Lift cylinder 14 is connected
• a storage connection 73 which is connected to the hydraulic accumulator 40.
• the control valve 70 fulfills the function of the check valve.
• the control valve 70 is acted upon in the sense of a connection of the accumulator connection 73 to the filler connection 71 by a compression spring 74, the prestressing force of which determines the accumulator pressure which is to occur in the hydraulic accumulator 40 at most.
• the control valve 70 is acted upon by the consumer pressure on a first control surface 75.
• the pressure on a second control surface 76 which acts in the same direction as the consumer pressure, can be controlled by an electromagnetically actuated pilot valve 77.
• the control surface 76 In the rest position of the pilot valve 77, the control surface 76 is relieved of pressure towards the leak oil line 46.
• the maximum pilot pressure for the directional valve 15 prevailing in the control pressure line 78 is applied to it.
• a switchable stroke limiter is provided for the control valve 70, which essentially consists of a stop piston 79 which is acted upon by the maximum pilot pressure in the rest position of the pilot valve 77 and then only permits the control valve 70 to be switched from the first switching position to the middle position.
• the stop piston 79 In the second switching position of the pilot valve 77, the stop piston 79 is relieved of pressure, so that the control valve 70 can be switched through to the second lateral switching position.
• the pilot valve 77 is in its rest position, in which the control surface 76 is relieved of pressure and the stop piston 79 is loaded with pilot pressure.
• the control valve 70 is in the first lateral switching position due to the action of the spring 74, in which pressure medium can flow from the filling connection 71 to the storage connection 73. A pressure medium flow in the opposite direction is prevented by the check valve 43.
• the hydraulic accumulator 40 is charged to the highest consumer pressure that has occurred.
• control valve 70 is adjusted to its central position due to the fact that the control surface 75 is subjected to the consumer pressure against the force of the spring 74. An adjustment beyond that is reliably avoided by the stop piston 79. The memory is protected from the high consumer pressure.
• the pilot valve 77 is switched to dampen pitch vibrations.
• the stop piston 79 is thereby relieved of pressure and the control surface 76 is loaded with pressure.
• the control valve 70 therefore safely reaches its second lateral switching position, in which the consumer connection 72 and the storage connection 73 IO are connected to one another, so that a free flow of pressure medium between the pressure chambers 28 of the lift cylinders 14 and the pressure accumulator 40 is possible.
• control block 10 is shown even more schematically than in Figures 1 to 3 as a bare rectangle. It contains several directional valve segments of the
• a filling line 41 in which a filling valve 85 is located, starts from an intermediate section of the main line.
• This is designed as a 2/2-way pressure reducing valve, which can close the fluidic connection between its 0 inlet 86 and its outlet 87, which can be connected to the hydraulic accumulator 40 via a check valve 43, without leakage.
• the filling valve 85 has a control piston 88, which is designed as a stepped piston with a small area difference 5 and is arranged accordingly stepped valve bore 89 of a valve housing 90 is located.
• the control piston has a first piston collar 91 of large diameter, which has a guiding function and separates the inlet bore 86 opening into the valve bore 89 from a leakage bore 92 opening axially at a distance therefrom into the valve bore. Closes the piston collar 91 a piston neck and a closing cone 93 of the control piston 88 adhere to the inlet bore 86.
• I O control piston 88 acted upon in the direction of opening the connection between the input 86 and the output 87.
• the spring chamber is connected to the outlet 87 on the other end face of the control piston 88 via an axial bore 98 which extends completely through the control piston 88.
• the filling valve 85 is kept open by the compression spring 97, as long as the storage pressure on an active surface, which corresponds in size to the surface 103, generates a force which is less than the force of the compression spring 97.
• the pre-tension of the compression spring is designed for the desired maximum storage pressure. If this storage pressure is reached, it can close the filling valve 85, so that the storage 40 is protected from higher pressures.
• the pressure relief valve 60 is additionally provided. In the embodiment according to FIG. 5, it is not the storage pressure that acts on the surfaces 101 and 102, but the pressure from the intermediate section of the main line at the inlet 86 of the filling valve 85. This can be accomplished in a simple manner 5 by swapping inlet 86 and outlet 87 with one another in the filling valve shown in FIG.
• shut-off valve 110 which is actuated directly by an electromagnet and is used as a 4/2
• I O directional valve is formed.
• the compensation line 44 running between the pressure chambers 28 of the lift cylinders 14 and the hydraulic accumulator 40 is interrupted.
• a connection between the pressure chambers 30 of the lift cylinders 14 and a tank line 22 is also interrupted. If the electromagnet 111 of the shut-off valve 110 is energized, it reaches its second one
• the hydraulic accumulator 40 is also filled when the directional control valve 15 connects the pressure chambers 30 of the lift cylinders 14 to the pressure medium source 59.
• the vehicle operator is set to a delayed build-up of pressure or to a movement when the damping system is switched on after the previous work cycle.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Civil Engineering (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Transportation (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Fluid-Pressure Circuits (AREA)
• Lifting Devices For Agricultural Implements (AREA)
• Operation Control Of Excavators (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7902531

Family Applications (1)

Country Status (4)

Families Citing this family (21)

Family Cites Families (6)

• 1999
  • 1999-03-26 DE DE19913784A patent/DE19913784A1/de not_active Withdrawn
• 2000
  • 2000-03-15 EP EP00912605A patent/EP1165895B1/fr not_active Expired - Lifetime
  • 2000-03-15 AT AT00912605T patent/ATE238465T1/de not_active IP Right Cessation
  • 2000-03-15 DE DE50001872T patent/DE50001872D1/de not_active Expired - Fee Related
  • 2000-03-15 WO PCT/EP2000/002263 patent/WO2000058570A1/fr active IP Right Grant

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events