DE102014113209A1 - Mobile work machine, in particular industrial truck - Google Patents

Abstract

The invention relates to a mobile work machine, in particular industrial truck, with a lifting device (2) for raising and lowering a load (L), wherein the lifting device (2) comprises a hydraulic lifting cylinder device (15), to whose control a control valve device (23) is provided which controls the connection of a pressure chamber (25) of the lifting cylinder device (15) with a hydraulic pump (20) and a container (21), wherein the pressure chamber (25) of the lifting cylinder device (15) is connectable to a hydraulic device for shock absorption (30) comprising a biasing space (31a) under a gas bias and a fluid space (31b) connectable to the pressure space (25). The hydraulic device for shock absorption (30) is designed as a double piston accumulator (31), by means of which the gas pressure of the gas bias of the preload space (31a) during operation of the machine is automatically adapted to the loading state of the lifting device (2).

Description

The invention relates to a mobile work machine, in particular industrial truck, with a lifting device for raising and lowering a load, wherein the lifting device comprises a hydraulic Hubzylindereinrichtung, for controlling a control valve device is provided which controls the connection of a pressure chamber of Hubzylindereinrichtung with a hydraulic pump and a container in which the pressure space of the lifting cylinder device can be connected to a hydraulic device for shock absorption, which has a prestressing space which is under a gas pretension and a fluid space which can be connected to the pressure space.

Mobile machines, such as industrial trucks, usually have an attachment, such as a load handling device, can be lifted and transported with the loads.

For lifting or lowering the load, a hydraulic Hubzylindereinrichtung is provided, which may consist of one or more lifting cylinders, which are directly or indirectly, often via a lifting chain or a lifting belt, connected to the load receiving means. The force required to lift the load is generated by the Hubzylindereinrichtung whose pressure chamber is connected via a hydraulic connecting line with a control valve device, such as a control way valve. The control valve device generally has three switching positions, wherein the pressure chamber of the lifting cylinder device can optionally be connected to a container for lifting the load with a hydraulic pump or to lower the load or shut off to hold the load. According to the respective switching position of the control valve device, the load is raised, lowered or held in the current position.

When the switching position of the control valve device is closed, the lifting cylinder device constitutes an at least approximately rigid component, whereby the load receiving means is not movably coupled to the frame of the working machine. As a result of this rigid coupling vibrations and shocks, for example, due to driving on road bumps, directly and directly transmitted from the load-carrying means to the load thereon and to the frame of the working machine.

In order to absorb this shock resulting from the road bumps and vibrations occurring during operation of the working machine, wherein the lifted load is carried by the liquid column of the Hubzylindereinrichtung, and to save the recorded load, it is already known, the pressure chamber of Hubzylindereinrichtung with a hydraulic device for To connect shock absorption, which comprises one or more gas pressure accumulator in known solutions. A gas pressure accumulator has a biasing space under a gas bias and a fluid space connectable to the pressure space of the lifting cylinder device. At this time, the bias pressure in the gas-filled bias space of the gas pressure accumulator is made unique to the rated load of the work machine, i. the maximum load capacity and the maximum load weight of a load of the working machine to be picked up, in order to be able to reduce the shocks and vibrations occurring at the highest load weight of a load that can be picked up.

However, such a gas pressure accumulator, which is designed for the nominal load of the working machine to reduce the shocks and vibrations at nominal load of the working machine, it only allows only for a certain load condition and thus a specific load case, namely at rated load, the shock absorption and the Load conservation by the gas pressure accumulator is optimal and for other load conditions and thus other load cases, such as the operation of the machine without load or with a load less than the rated load, no satisfactory load protection and no satisfactory reduction of shock and vibration loads is achieved.

The present invention has for its object to provide a mobile machine of the type mentioned available that enables low-cost shock absorption and load protection by the hydraulic device for shock absorption for different loading conditions.

This object is achieved in that the hydraulic device for shock absorption is designed as a double piston accumulator, by means of which the gas pressure of the gas bias of the preload space during operation of the machine is automatically adapted to the loading state of the lifting device. With a double piston accumulator, which forms the hydraulic device for shock absorption, the gas pressure of the gas bias of the biasing space of the double piston accumulator and thus the spring stiffness of the double piston accumulator and thus the hydraulic device for shock absorption in a simple way automatically added to the current load condition and thus to different load weights of a current Load to be adjusted. Thus, with a double piston accumulator, the shock absorption and the load protection by the hydraulic device for shock absorption can be automatically adapted to the current loading state in a simple manner, so that the operating machine can operate with different degrees of difficulty Loads at any time optimum shock absorption and load-saving is achieved with the hydraulic device for shock absorption.

According to an advantageous embodiment of the invention, the double piston accumulator on a first piston, which is arranged longitudinally displaceably in a housing of the double piston accumulator, and a second piston, which is arranged longitudinally displaceably in the housing of the double piston accumulator, wherein the stationary under a gas bias biasing space between the two Piston is formed, the first piston is used for shock absorption and the second piston forms an actuating piston, which allows adjustment of the gas pressure of the gas bias of the biasing space in the operation of the working machine to the loading state of the lifting device. The double-piston accumulator thus has two pistons longitudinally displaceable in the housing of the double-piston accumulator and thus arranged in a floating manner. Between the two pistons of the gas-filled and under the gas biasing biasing space of the hydraulic device is designed for shock absorption. The first piston has the function of the hydraulic shock absorption device. The second piston forms an actuating piston with which the gas pressure in the preload space can be adapted to the current load condition. With such a double-piston accumulator, which has the function of the hydraulic device for shock absorption on the first piston and the function of a control piston on the second piston, with which the gas pressure in the biasing space of the hydraulic device for shock absorption can be adapted to the current load state, can low construction cost and low space requirement in a particularly cost-effective manner, the gas pressure in the gas-filled biasing space and thus the spring stiffness of the hydraulic shock absorption device to be changed to automatically adjust the gas pressure of the hydraulic shock absorbing device to the current load state and thus to achieve the currently recorded load ,

The dual-piston accumulator can form the function of the hydraulic device for shock absorption at low construction costs with the first piston, if, according to an advantageous embodiment of the invention, the first piston with the housing forms the fluid space which is connectable to the pressure chamber of Hubzylindereinrichtung.

The dual-piston accumulator can form the function of the adjusting piston with the second piston with low construction costs, with which the gas pressure in the preload space can be adapted to the current loading state, if forms according to an advantageous embodiment of the invention, the second piston with the housing a control pressure chamber of the actuating piston, which serves to adapt the gas pressure of the gas bias of the biasing space.

According to an advantageous embodiment of the invention, the control pressure chamber of the actuating piston for adapting the gas pressure of the gas bias of the biasing space with the pressure chamber of the lifting cylinder device is connectable. In this way it is achieved that the control pressure chamber of the control piston is acted upon by the current load pressure of the lifting cylinder device. As a result, the gas pressure of the gas bias of the preload space can be adapted to the current load state with little construction effort, since the actual load pressure in the pressure chamber of the lifting cylinder device is a measure of the load weight of a currently recorded load.

According to an advantageous embodiment of the invention, the second piston is designed as a stepped piston, wherein the piston has a first piston surface in the control pressure chamber and a second piston surface in the biasing space. With a stepped piston having different sized first and second piston surfaces on the gas side and on the fluid side, can be achieved with low construction costs by the ratio of the piston surfaces to adapt to the pressure ratio between the fluid side and the gas side of the double piston accumulator.

Preferably, the first piston area is smaller than the second piston area. In general, the gas pressure in the biasing space is less than the load pressure in the pressure chamber of the Hubzylindereinrichtung. If the first piston surface on the fluid side is smaller than the second piston surface on the gas side of the double piston accumulator, the applied load pressure level can be transferred to a lower gas pressure level in a simple manner.

According to an advantageous embodiment of the invention, a first control valve is provided, by means of which the connection of the fluid space of the double piston accumulator with the pressure chamber of the lifting cylinder device or with a container is controllable. By connecting the fluid space of the double piston accumulator with the pressure chamber of the lifting cylinder device, the function of the hydraulic device for shock absorption of the double piston accumulator can be activated in a simple manner by means of a control valve in order to achieve a shock absorption and load protection. By connecting the fluid space of the double piston accumulator with the container, the fluid space of the double piston accumulator for adjusting and adjusting the gas pressure in the preload space of the double piston accumulator can be switched to the current loading state in a simple manner by means of a control valve.

For this purpose, the first control valve advantageously has a first control position, in which the fluid chamber of the double piston accumulator is connected to the pressure chamber of the lifting cylinder device, and a second control position, in which the fluid chamber of the double piston accumulator is connected to the container.

Advantageously, the first control valve has a third control position, in which the fluid space of the double piston accumulator is shut off. With such a third control position, the function of the hydraulic device for shock absorption of the double piston accumulator and thus the shock absorption and load protection by the double piston accumulator can be deactivated in a simple manner.

Conveniently, the first control valve is designed as a proportional valve.

According to an advantageous development of the invention, a second control valve is provided, by means of which the connection of the control pressure chamber of the double piston accumulator with the pressure chamber of the lifting cylinder device or with the container is controllable. Such a second control valve makes it possible in a simple manner to adjust the pressure in the control pressure chamber of the control piston of the double piston accumulator by the control pressure chamber of the control piston with the pressure chamber of Hubzylindereinrichtung or with the container is connectable. By connecting the control pressure chamber of the control piston with the pressure chamber of the lifting cylinder device, the gas pressure in the gas-filled prestressing chamber of the double piston accumulator can be increased in a simple manner. By connecting the control pressure chamber of the control piston with the container can be reduced in a simple way, the gas pressure in the gas-filled biasing chamber of the double piston accumulator. With the adjusting piston of the double piston accumulator and the second control valve can thus be adapted in a cost effective manner, the gas pressure in the gas-filled biasing chamber of the double piston accumulator to the current load condition.

For this purpose, the second control valve advantageously has a first control position, in which the control pressure chamber of the double piston accumulator is connected to the pressure chamber of the lifting cylinder device, and a second control position, in which the control pressure chamber of the double piston accumulator is connected to the container.

The second control valve expediently has a third control position, in which the control pressure chamber of the double piston accumulator is shut off.

Conveniently, the second control valve is designed as a proportional valve.

According to an advantageous embodiment of the invention, the double-piston accumulator can be controlled by means of an electronic control device which is connected on the input side to a sensor device detecting the load weight of a picked-up load and / or to a sensor device detecting the travel speed of the machine. With an electronic control device, the gas pressure in the gas-filled prestressing space of the double-piston accumulator can be adjusted automatically to the current load state in a simple manner by controlling the two control valves, so that at any time optimal shock absorption and load protection is achieved with the double piston accumulator.

The electronic control device is designed according to an embodiment of the invention such that when receiving a load for adjusting the gas pressure in the biasing space of the double piston accumulator to the current load state, the fluid chamber of the double piston accumulator is depressurized and the control pressure chamber of the double piston accumulator is connected to the pressure chamber of Hubzylindereinrichtung. By a depressurization of the fluid space of the double piston accumulator, the gas pressure in the gas-filled biasing chamber of the double piston accumulator by appropriate connection of the control pressure chamber of the double piston accumulator with the pressure chamber of Hubzylindereinrichtung, wherein the control pressure chamber is acted upon by the load pressure in the pressure chamber of Hubzylindereinrichtung, in a simple manner when receiving a load the current load weight and thus the current load condition can be adjusted.

The electronic control device is according to an embodiment of the invention further designed such that when depositing a load to adjust the gas pressure in the preload space of the double piston accumulator to a load-free loading state, the fluid space of the double piston accumulator is shut off and the control pressure chamber of the double piston accumulator is depressurized. By shutting off the fluid space of the double piston accumulator and depressurizing the control pressure chamber of the double piston accumulator, the double piston accumulator can be brought into a neutral position, in which the second piston is displaced from the pressure in the fluid chamber to a stop. Preferably, the setting of the double piston accumulator in this neutral position corresponds to a load-free loading state. After activation of the function of the hydraulic device for shock absorption of the double piston accumulator rattling noise of the lifting device when driving without load or when driving with empty transport containers and thus a light load can be easily reduced.

The electronic control device is advantageously designed such that after the adaptation of the gas pressure in the preload space of the double piston accumulator, the shock absorption is activated by the double piston accumulator, in which the fluid space of the double piston accumulator is connected to the pressure chamber of Hubzylindereinrichtung and the control pressure chamber is shut off. In this way can be achieved in a simple manner that when driving the machine with an empty load-receiving device or with a recorded load, the shock absorption function of the double piston accumulator is activated to achieve a vibration absorption and load protection.

The automatic adjustment of the gas pressure of the double piston accumulator to the current load state can be achieved in a simple manner, when the first control valve is controlled by the electronic control device according to an embodiment of the invention, wherein the control valve for adjusting the gas pressure in the biasing space of the double piston accumulator when receiving a load in Direction of the second control position is actuated and is actuated to adjust the gas pressure in the biasing space of the double piston accumulator when depositing a load in the direction of the third control position. As a result, it is achieved in a simple manner that when receiving a load for adjusting the gas pressure to the loading state, the fluid space is depressurized and shut off when settling a load to adjust the gas pressure to the loading state of the fluid space.

An automatic activation of the shock absorption and load protection by the double piston accumulator after adjusting the gas pressure to the current load state is achieved in a simple manner when the first control valve is actuated by the electronic control device for activating the shock absorption by the double piston accumulator in the direction of the first control position, in which Fluid space of the double piston accumulator is connected to the pressure chamber of Hubzylindereinrichtung.

An automatic deactivation of the shock absorption and load protection by the double piston accumulator is achieved in a simple manner when the first control valve is actuated by the electronic control device for deactivating the shock absorption by the double piston accumulator in the third control position.

The automatic adjustment of the gas pressure of the double piston accumulator to the current load state can be achieved in a simple manner, when the second control valve is controlled by the electronic control device according to an embodiment of the invention, wherein the second control valve for adjusting the gas pressure in the biasing space of the double piston accumulator when receiving a load is actuated in the direction of the first control position, so that the control pressure chamber of the double piston accumulator is connected to the pressure chamber of the hydraulic cylinder device and thus the load pressure in the control pressure chamber of the double piston accumulator, and to adjust the gas pressure in the biasing space of the double piston accumulator when depositing a load in the direction of the second control position is pressed to depressurize the preload space.

The second control valve is actuated by the electronic control device for activating the shock absorption by the double piston accumulator expediently in the third control position.

Expediently, furthermore, the second control valve is actuated by the electronic control device when the shock absorption is deactivated by the double piston accumulator into the second control position.

The electronic control device is designed according to an advantageous embodiment of the invention such that after each deactivation of the shock absorption, a calibration of the double piston accumulator is performed on the current load condition.

To calibrate the dual-piston accumulator to the current load state of the electronic control device in a first step, the first control valve in the third control position and the second control valve is operated in the second control position, in a second step, the first control valve in the second control position and the second control valve in the first control position is actuated. By actuating the first control valve in the third control position and the second control valve in the second control position in the first step is achieved that the fluid space of the double piston accumulator is shut off and the control pressure chamber of the double piston accumulator is relieved to the container. The pressure present in the fluid space therefore displaces the first piston and the second piston against a stop. Subsequently, in the second step, an actuation of the first control valve in the second control position achieves that the fluid space of the double piston accumulator is relieved of the container, so that the actuating pressure chamber of the double piston accumulator is connected to the pressure chamber of the hydraulic cylinder device by actuating the second control valve into the first control position is and thus the load pressure in the preload space of Dual piston accumulator is present and the double piston accumulator is set to the current load condition. Subsequently, the shock absorption by the double piston accumulator can be activated by actuation of the second control valve in the third control position and actuation of the first control valve in the first control position.

Particular advantages arise when, according to a development of the invention, the electronic control device controls the shock absorption by the double piston accumulator and / or the pressure adjustment of the gas pressure in the preload space of the double piston accumulator as a function of the driving speed.

The electronic control device is advantageously designed such that when falling below a Grenzfahrgeschwindigkeit the shock absorption is deactivated by the double piston accumulator and carried out when exceeding the Grenzfahrgeschwindigkeit an adjustment of the gas pressure in the preload space of the double piston accumulator and the shock absorption is activated by the double piston accumulator. As a result, can be achieved in a simple way that when driving the machines above the Grenzfahrgeschwindigkeit the adjustment of the gas pressure of the double piston accumulator is performed on the current load condition and the shock absorption and load protection is activated by the double piston accumulator and falls below the Grenzfahrgeschwindigkeit the shock absorption and load protection by the double piston accumulator is automatically deactivated to facilitate the picking up or setting down of a load.

Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. This shows

1 a mobile work machine in a side view and

2 a hydraulic circuit diagram of the working machine according to the invention.

In the 1 is an industrial truck 1 represented as an example of a mobile working machine according to the invention. The conveyor belt 1 is formed in the illustrated embodiment as a counterbalance forklift.

The truck 1 is in the front area with a lifting device designed as a mast 2 for lifting and lowering a lifting device 3 Mistake. In the rear area is the truck 1 with a counterweight 4 Mistake. The truck 1 includes a vehicle body 5 with a frame and on the vehicle body 5 arranged driver's roof 6 within which there is a driver's workplace 7 located. The driver's workplace 7 includes in the present embodiment, a driver's seat 8th , a steering device 9 and at least one foot pedal arranged in the pedal for controlling a traction drive, not shown. Furthermore, in the driver's workplace 7 several controls 10 arranged for a working hydraulics, which is a lifting drive for raising and lowering the lifting device 3 having. The working hydraulics can optionally be a tilt drive 14 the mast and an additional consumer include, for example, a side shift drive for the load-carrying means 3 , The truck 1 supports itself by means of front wheels 11 and one or more rear wheels 12 on a roadway 13 from.

The mast is executed in the illustrated embodiment as Mehrfachhubgerüst in the execution of a duplex mast. The duplex mast includes a stand mast 2a , which is formed by two laterally arranged in the vehicle transverse direction vertical mast profiles. The stationary mast 2a can by means of the tilt drive 14 , which is formed by tilt cylinders, adjustable in inclination on the truck 1 be arranged. At the mast 2a is an extension mast 2 B raised and lowered arranged on which the load-carrying means 3 is arranged liftable and lowerable. The load handling device 3 is in the illustrated embodiment of a fork with two forks 3a educated. The forks 3a are on a fork carriage 3b arranged on the extension mast 2 B is arranged adjustable in height.

For lifting and lowering the load handler 3 has the lifting device 2 as a lifting drive a hydraulic Hubzylindereinrichtung 15 on.

The truck 1 has an unsprung suspension. The front wheels 11 and the rear wheels 12 are without suspension on the vehicle body 5 or the counterweight 4 arranged. The lifting device 2 is also without suspension on the vehicle body 5 or one of the front wheels 11 supporting drive axle attached.

The roadway 13 has bumps in this example 16 on. When driving over the bumps 16b Vibrations and shocks on the load handler 3 located and from the Hubzylindereinrichtung 15 carried load L and on the vehicle body 5 transfer.

In the 2 is a hydraulic circuit diagram of the lifting device 2 illustrated the mobile machine according to the invention.

A hydraulic pump 20 sucks pressure medium, such as hydraulic oil, from a container 21 and is about a promotion line 22 with a control valve device 23 connected to the Hubzylindereinrichtung 15 and thus the lifting movement and lowering movement of the load receiving means 3 is controllable. This is a connection line 24 provided, which is the control valve device 23 with a pressure room 25 the lifting cylinder device 15 combines. To the control way valve 23 is still one to the container 21 guided container line 27 connected.

The control valve device 23 has a neutral position, a lifting position and a lowering position. In the neutral position, which the control valve device 23 For example, due to spring force occupies rest, is the connecting line 24 shut off. In this switching position is the control valve device 23 if no signal for raising or lowering the load L is given by the operator. To raise the load L, the control valve device 23 acted upon in the lifting position, in which the hydraulic pump 20 with the connection line 24 the lifting cylinder device 15 is connected, whereby piston rods of Hubzylindereinrichtung 15 as a result of in the pressure chamber 25 the lifting cylinder device 15 Extend the pressure upwards. To lower the load L, the control valve device 23 acted upon in the lowering position, in which the connecting line 24 the lifting cylinder device 15 with the container line 27 connected, causing the pressure chamber 25 the lifting cylinder device 15 with the container 21 is connected and the piston rods of Hubzylindereinrichtung 15 drive in down.

In the illustrated embodiment is of the Hubzylindereinrichtung 15 only one lifting cylinder shown. The lifting cylinder is designed as a single-acting plunger cylinder, which has an extending in a cylinder housing piston rod and between the cylinder housing and the piston rod a corresponding pressure chamber 25 forms. It is understood that the Hubzylindereinrichtung 15 may include several lifting cylinders.

The pressure room 25 the lifting cylinder device 15 is to reduce the load L and the vehicle body 5 acting vibrations and load shocks when driving over bumps 16 and thus for shock absorption in the lifting device 2 and for the load-saving of the load L with a hydraulic device for shock absorption 30 connectable.

The hydraulic device for shock absorption 30 has a filled with gas, such as nitrogen or air, and under a gas bias biasing space 31a and a pressure medium filled fluid space 31b on. The fluid space 31b is for shock absorption in the lifting device 2 and for the protection of the load with the pressure chamber 25 the lifting cylinder device 15 connectable. For this purpose, in the illustrated embodiment, the fluid space 31b by means of a connecting line 32 to the connection line 24 connected.

According to the invention, the hydraulic device is for shock absorption 30 as a double piston accumulator 31 educated. With the double piston accumulator 31 allows the gas pressure of the gas bias of the biasing space 31a during operation of the work machine automatically to the loading state of the lifting device 2 adapt.

The double piston accumulator 31 has a housing 35 in which a first piston 36 and a second piston 37 each longitudinally displaceable and thus arranged to float. The gas filled and biased biasing space 31a is between the two pistons 36 and 37 formed so that the two pistons 36 . 37 include the gas volume. The first piston 36 serves with the fluid space 31b for shock absorption and ensures shock absorption in the lifting device 2 and thus the load-saving of a recorded load L. The second piston 37 forms an actuating piston 38 , which is an adjustment of the gas pressure of the gas bias of the biasing space 31a during operation of the working machine to the current loading state of the lifting device 2 allows. With the adjusting piston 38 it allows the gas pressure and thus the spring stiffness of the double piston accumulator 31 to be able to adapt to different load weights of a recorded load L and thus the current load condition and thus to achieve optimal shock absorption at different load weights of a recorded load L.

The first piston 36 forms for this purpose with the housing 35 the fluid space 31b ,

The second piston 37 forms with the housing 35 a signal pressure chamber 39 of the adjusting piston 38 , which adjusts the gas pressure of the gas bias of the biasing space 31a serves.

In the illustrated embodiment, the control pressure chamber 39 of the adjusting piston 38 for adjusting the gas pressure of the gas bias of the biasing space 31a with the pressure room 25 the lifting cylinder device 15 connectable. For this purpose, in the illustrated embodiment, the control pressure chamber 39 by means of a connecting line 40 to the connection line 24 connected.

The second piston 37 is formed in the illustrated embodiment as a stepped piston having a first, fluid-side piston surface 37a in the signal pressure chamber 39 and a second, gas-side piston surface 37b in the leader room 31a having. The piston surfaces 37a . 37b are different sizes, in the illustrated embodiment, the first piston surface 37a smaller than the second piston area 37b is. The ratio of piston areas 37a . 37b corresponds to the pressure ratio between that of the control room pressure 39 formed fluid side and that of the biasing space 31a formed gas side of the actuator piston 38 ,

For controlling the double piston accumulator 30 is a first control valve 50 provided by means of which the connection of the fluid space 31b of the double piston accumulator 31 with the pressure room 25 the lifting cylinder device 15 or with the container 21 is controllable. The control valve 50 has a first control position 50a on, in the fluid space 31b of the double piston accumulator 31 with the pressure room 25 the lifting cylinder device 15 connected, and a second control position 50b on, in the fluid space 31b of the double piston accumulator 31 with the container 21 is connected and thus the fluid space 31b of the double piston accumulator 31 is depressurized. The first control valve 50 also has a third control position 50c on, in the fluid space 31b of the double piston accumulator 31 is locked. The first control valve 50 is formed in the illustrated embodiment as throttling in intermediate positions proportional valve. The first control valve 50 thus serves to activate the shock absorption by the double piston accumulator 31 in the first control position 50a the fluid space 31b with the pressure room 25 the lifting cylinder device 15 and deactivating the shock absorption by the double piston accumulator 31 in the third control position 50c the fluid space 31b shut off and thus the fluid space 31b from the pressure room 25 the lifting cylinder device 15 is disconnected. The control valve 50 serves in the second control position 51b for depressurization of the fluid space 31b of the double piston accumulator 31 by the fluid space 31b with the container 21 is connected.

For controlling the double piston accumulator 30 is a second control valve 55 provided by means of the connection of the control pressure chamber 39 of the double piston accumulator 31 with the pressure room 25 the lifting cylinder device 15 or with the container 21 is controllable. The second control valve 55 has a first control position 55a on, in which the signal pressure chamber 39 of the double piston accumulator 31 with the pressure room 25 the lifting cylinder device 15 connected, and a second control position 55b on, in which the signal pressure chamber 39 of the double piston accumulator 31 with the container 21 connected is. The second control valve 55 also has a third control position 55c on, in which the signal pressure chamber 39 of the double piston accumulator 31 with the pressure room 25 the lifting cylinder device 15 is locked. The second control valve 55 is formed in the illustrated embodiment as throttling in intermediate positions proportional valve. With the second control valve 55 can thus the pressure in the control pressure chamber 39 and thus the gas pressure in the gas-filled biasing space 31a of the double piston accumulator 31 be set. At an admission of the second control valve 55 in the direction of the first control position 55a can the gas pressure in the biasing space 31a of the double piston accumulator 31 increase. Accordingly, when the second control valve is acted upon 55 in the direction of the second control position 55b the gas pressure in the biasing space 31a of the double piston accumulator 31 be reduced.

The two control valves 50 . 55 are by means of an electronic control device 60 controllable. The electronic control device 60 is on the input side with a load weight of the load L detecting sensor device 61 and / or a sensor device detecting the travel speed of the work machine 62 in connection. The sensor device 61 is formed in the illustrated embodiment as a pressure sensor, the load pressure in the pressure chamber 25 the lifting cylinder device 15 detected.

The first control valve 50 is for driving by the electronic control device 60 with electrical controls 65a . 65b , For example, proportional magnets, provided with which the first control valve 50 in the direction of the tax positions 50a . 50b is operable. The second control valve 55 is for driving by the electronic control device 60 with electrical controls 66a . 66b , For example, proportional magnets, provided with which the second control valve 55 in the direction of the tax positions 55a . 55b is operable.

The system according to the invention with the adaptable to the current load condition double piston accumulator 31 works as follows.

With shock absorption deactivated by the double piston accumulator 31 is the first control valve 50 in the third control position 50c operated and the second control valve 55 in the second control position 55b actuated, in which the control pressure chamber 39 to the container 21 is relieved. The second piston 37 is here after in the 2 pressed right and is located on a right stop 41 in the illustrated embodiment of the Diameter of the stepped piston 38 and a housing shoulder of the housing 35 is formed. This condition corresponds to a neutral position of the double piston accumulator 31 ,

Used with the lifting device 2 picked up a load L, the load pressure in the pressure chamber increases 25 the lifting cylinder device 15 at. From the electronic control device 60 is used to adjust and adjust the gas pressure in the biasing space 31a of the double piston accumulator 31 to the current load state when receiving a load L by means of a control of the first control valve 50 in the direction of the second control position 50b the fluid space 31b of the double piston accumulator 31 to the container 21 Relieves and then the second control valve 55 in the direction of the first control position 55a actuated, in which the control pressure chamber 39 of the double piston accumulator 31 with the pressure room 25 connected is. The signal pressure chamber 39 of the adjusting piston 38 and thus the actuator piston 38 is thus acted upon by the current load pressure. The one in the leader room 31a Pending gas pressure corresponds to the ratio of the piston surfaces 37a . 37b designed as a stepped piston second piston 37 , The one in the leader room 31a Pending gas pressure can thus by applying the control pressure chamber 39 be adjusted with the current load pressure to the current load condition. After adjusting the gas pressure in the biasing space 31a to the current loading state are from the electronic control device 60 the second control valve 55 in the third control position 55c operated as well as the control valve 50 in the first control position 50a operated, in the fluid space 31b with the pressure room 25 connected to the shock absorption through the fluid space 31b and the first piston 36 of the double-piston accumulator 31 to activate.

After receiving the load and adjusting the gas pressure in the preload space 31a of the double piston accumulator 31 may be a transport of the recorded load L with activated shock absorption by the first piston 36 of the double piston accumulator 31 be performed, with the adjusted by the current load pressure and thus to the current load weight of a recorded load L gas pressure in the preload space 31a of the double piston accumulator 31 and thus adapted to the current load weight spring stiffness of the double piston accumulator 31 optimum shock absorption and load protection is achieved.

Used with the lifting device 2 set off a load L, the load pressure in the pressure chamber decreases 25 the lifting cylinder device 15 , To the double piston accumulator 31 is again positioned in the neutral position, by the electronic control device 60 when settling the load L by means of a control of the first control valve 50 in the direction of the third control position 50c the fluid space 31b of the double piston accumulator 31 shut off and the second control valve 55 in the direction of the second control position 55b actuated, in which the control pressure chamber 39 of the double piston accumulator 6 with the container 21 connected is. The one in the fluid space 31b upcoming higher pressure acts on both pistons 36 . 37 after in the 2 right until the actuator piston 38 forming second piston 37 to the right stop 41 passes and rests against this. The double piston accumulator 31 is then again in the deactivated state, in which the shock absorption by the double piston accumulator 31 is switched off.

In the third control position 55c located second control valve 55 can by controlling the control valve 50 in the direction of the first control position 50a the shock absorption by the double piston accumulator 31 be activated or by controlling the control valve 50 in the third control position 50c the shock absorption by the double piston accumulator 31 be deactivated.

From the electronic control device 60 is hereby preferred after each deactivation of the shock absorption of the double piston accumulator 31 a calibration of the double piston accumulator 31 performed on the current load condition, by in a first step by means of a control of the first control valve 50 in the direction of the third control position 50c the fluid space 31b of the double piston accumulator 31 shut off and by means of a control of the second control valve 55 in the direction of the second control position 55b the signal pressure chamber 39 of the double piston accumulator 6 with the container 21 is connected, so that in the fluid space 31b upcoming higher pressure both pistons 36 . 37 after in the 2 acted on the right until the actuator piston 38 forming second piston 37 to the right stop 41 passes and rests against this. Subsequently, in a second step by means of a control of the first control valve 50 in the direction of the second control position 50b the fluid space 31b of the double piston accumulator 31 to the container 21 relieved and by means of the control of the second control valve 55 in the direction of the first control position 55a the signal pressure chamber 39 of the double piston accumulator 31 with the pressure room 25 connected, so that the signal pressure chamber 39 of the adjusting piston 38 and thus the actuator piston 38 is acted upon by the current load pressure and the double piston accumulator 31 calibrated to the current load condition.

Subsequently, by a control of the second control valve 55 in the third control position 55c and by a control of the first control valve 50 in the first control position 50a the shock absorption due to the dual piston accumulator set to the current load condition 31 to be activated.

Adjusting the gas pressure in the biasing space 31a on the current load state can by the electronic control device 60 depending on the means of the sensor device 62 detected driving speed of the working machine are controlled.

When falling below a Grenzfahrgeschwindigkeit is preferred, the shock absorption by the double piston accumulator 31 disabled to absorb or absorb a load L shock absorption by the double piston accumulator 31 to turn off, thereby facilitating the picking and setting of a load L. When the limit travel speed is exceeded by the electronic control device 60 by appropriate control of the control valves 50 . 55 an adjustment of the gas pressure to the current load state performed and after adjusting the gas pressure to the current load state, the shock absorption by the double piston accumulator 31 activated when transporting a load L or while driving the work machine with empty load handling equipment 3 the shock absorption by the double piston accumulator 31 turn.

Alternatively or additionally, by the electronic control device 60 the automatic adjustment of the gas pressure in the biasing space 31a of the double piston accumulator 31 depending on the means of the sensor device 61 detected load pressure of the currently recorded load L and thus controlled by the detected current load state, so that the adjustment of the gas pressure is automatically carried out at a change in the measured load pressure.

The double piston accumulator according to the invention 31 , whose gas pressure in the preload space 31a can be adapted to the current load state, allows that at any time on the corresponding load state and thus adapted to the corresponding load L gas pressure in the gas-filled biasing space 31a of the double-piston accumulator 31 prevails and thus designed as a gas pressure accumulator double piston accumulator 31 having a matched to the respective load state spring stiffness. It is thus achieved for each load condition and different heavy loads L in a simple way optimum shock absorption and load protection. The inventive automatic adjustment of the gas pressure in the gas-filled biasing space 31a of the double-piston accumulator 31 to the current load condition and the currently recorded load, it also allows, with empty load handling equipment 3 and thus a load-free loading condition, the noise emissions by rattling components of the lifting device 2 while driving the mobile work machine can be reduced.

For variable loads L with different load weights and thus different load conditions can thus with the double piston accumulator according to the invention 31 an optimal shock absorption in the lifting device 2 and load conservation of a recorded load L can be achieved. By means of the electronic control device 60 is achieved in a simple manner that the gas pressure in the biasing space 31a of the double piston accumulator 31 automatically adapted to the recorded load L and the corresponding loading condition, in order to allow optimal load protection and shock absorption.

The double piston accumulator according to the invention 31 also has a low construction cost and a low space requirement, so that with little construction effort and shock absorption for different heavy loads L is achieved with the load handling equipment 3 be recorded.

Claims (29)

Mobile work machine, in particular industrial truck ( 1 ), with a lifting device ( 2 ) for lifting and lowering a load (L), wherein the lifting device ( 2 ) a hydraulic lifting cylinder device ( 15 ), to the control of which a control valve device ( 23 ) is provided which the connection of a pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) with a hydraulic pump ( 20 ) and a container ( 21 ), wherein the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) with a hydraulic device for shock absorption ( 30 ), which has a biasing space ( 31a ) and one with the pressure chamber ( 25 ) connectable fluid space ( 31b ), characterized in that the hydraulic device for shock absorption ( 30 ) as a double piston accumulator ( 31 ) is formed, by means of which the gas pressure of the gas bias of the biasing space ( 31a ) in the operation of the work machine automatically to the loading state of the lifting device ( 2 ) is customizable. Mobile work machine according to claim 1, characterized in that the double piston accumulator ( 31 ) a first piston ( 36 ) in a housing ( 35 ) of the double piston accumulator ( 31 ) is longitudinally displaceable, and a second piston ( 37 ), which in the housing ( 35 ) of the double piston accumulator ( 31 ) is arranged longitudinally displaceable, wherein the prestressing space ( 31a ) between the two pistons ( 36 . 37 ), the first piston ( 36 ) for shock absorption and the second piston ( 37 ) an actuating piston ( 38 ), which is an adaptation of the gas pressure of the gas bias of the biasing space ( 31a ) in the operation of Working machine to the loading state of the lifting device ( 2 ). Mobile work machine according to claim 2, characterized in that the first piston ( 36 ) with the housing ( 35 ) the fluid space ( 31b ). Mobile work machine according to claim 2 or 3, characterized in that the second piston ( 37 ) with the housing ( 35 ) a signal pressure chamber ( 39 ) of the adjusting piston ( 38 ), which for adjusting the gas pressure of the gas bias of the biasing space ( 31a ) serves. Mobile working machine according to claim 4, characterized in that the control pressure chamber ( 39 ) of the adjusting piston ( 38 ) for adjusting the gas pressure of the gas bias of the biasing space ( 31a ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) is connectable. Mobile work machine according to one of claims 2 to 5, characterized in that the second piston ( 37 ) is designed as a stepped piston, wherein the second piston ( 37 ) a first piston surface ( 37a ) in the signal pressure chamber ( 39 ) and a second piston surface ( 37b ) in the leader room ( 31a ) having. Mobile working machine according to claim 6, characterized in that the first piston surface ( 37a ) smaller than the second piston area ( 37b ). Mobile work machine according to one of claims 1 to 7, characterized in that a first control valve ( 50 ) is provided, by means of which the connection of the fluid space ( 31b ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) or with a container ( 21 ) is controllable. Mobile work machine according to claim 8, characterized in that the first control valve ( 50 ) a first control position ( 50a ), in which the fluid space ( 31b ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ), and a second control position ( 50b ), in which the fluid space ( 31b ) of the double piston accumulator ( 31 ) with the container ( 21 ) connected is. Mobile work machine according to claim 8 or 9, characterized in that the first control valve ( 50 ) a third control position ( 50c ), in which the fluid space ( 31b ) of the double piston accumulator ( 31 ) is locked. Mobile work machine according to one of claims 8 to 10, characterized in that the first control valve ( 50 ) is designed as a proportional valve. Mobile work machine according to one of claims 4 to 11, characterized in that a second control valve ( 55 ) is provided, by means of which the connection of the control pressure chamber ( 39 ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) or with the container ( 21 ) is controllable. Mobile work machine according to claim 12, characterized in that the second control valve ( 55 ) a first control position ( 55a ), in which the control pressure space ( 39 ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ), and a second control position ( 55b ), in which the control pressure space ( 39 ) of the double piston accumulator ( 31 ) with the container ( 21 ) connected is. Mobile work machine according to claim 12 or 13, characterized in that the second control valve ( 55 ) a third control position ( 55c ), in which the control pressure space ( 39 ) of the double piston accumulator ( 31 ) is locked. Mobile work machine according to one of claims 12 to 14, characterized in that the second control valve ( 55 ) is designed as a proportional valve. Mobile work machine according to one of claims 1 to 15, characterized in that the double-piston accumulator ( 31 ) by means of an electronic control device ( 60 ) is controllable, the input side with a load weight detecting sensor device ( 61 ) and / or a sensor device detecting the traveling speed of the working machine ( 62 ). Mobile work machine according to claim 16, characterized in that the electronic control device ( 60 ) is designed such that when receiving a load (L) for adjusting the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) to the current loading state of the fluid space ( 31b ) of the double piston accumulator ( 31 ) is depressurized and the signal pressure chamber ( 39 ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) is connected. Mobile work machine according to claim 16 or 17, characterized in that the electronic control device ( 60 ) is designed such that when a load (L) is set down to adjust the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) to a load-free loading state of the fluid space ( 31b ) of the double piston accumulator ( 31 ) is shut off and the control pressure chamber ( 39 ) of the double piston accumulator ( 31 ) is depressurized. Mobile work machine according to one of claims 16 to 18, characterized in that the electronic control device ( 60 ) is designed such that after the adaptation of the gas pressure in the preload space ( 31a ) of the double piston accumulator ( 31 ) the shock absorption by the double piston accumulator ( 31 ) is activated, in which the fluid space ( 31b ) of the double piston accumulator ( 31 ) with the pressure chamber ( 25 ) of the lifting cylinder device ( 15 ) and the signal pressure chamber ( 39 ) is shut off. Mobile work machine according to one of claims 16 to 19, characterized in that the first control valve ( 50 ) from the electronic control device ( 60 ), wherein the control valve ( 50 ) for adjusting the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) when picking up a load (L) in the direction of the second control position ( 50b ) and for adjusting the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) when depositing a load (L) in the direction of the third control position ( 50c ) is actuated. Mobile work machine according to one of claims 16 to 20, characterized in that the first control valve ( 50 ) from the electronic control device ( 60 ) for activating the shock absorption by the double piston accumulator ( 31 ) in the direction of the first control position ( 50a ) is actuated. Mobile work machine according to one of claims 16 to 21, characterized in that the first control valve ( 50 ) from the electronic control device ( 60 ) for deactivating the shock absorption by the double piston accumulator ( 31 ) into the third control position ( 50c ) is actuated. Mobile work machine according to one of claims 16 to 22, characterized in that the second control valve ( 55 ) from the electronic control device ( 60 ), wherein the second control valve ( 55 ) for adjusting the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) when picking up a load (L) in the direction of the first control position ( 55a ) and for adjusting the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) when depositing a load (L) in the direction of the second control position ( 55b ) is actuated. Mobile work machine according to one of claims 16 to 23, characterized in that the second control valve ( 55 ) from the electronic control device ( 60 ) for activating the shock absorption by the double piston accumulator ( 31 ) into the third control position ( 55c ) is actuated. Mobile work machine according to one of claims 16 to 24, characterized in that the second control valve ( 55 ) from the electronic control device ( 60 ) with deactivated shock absorption by the double piston accumulator ( 31 ) in the second control position ( 55b ) is actuated. Mobile work machine according to one of claims 16 to 25, characterized in that the electronic control device ( 60 ) is designed such that after each deactivation of the shock absorption, a calibration of the double-piston accumulator ( 31 ) is performed on the current load condition. Mobile work machine according to claim 26, that for calibrating the double-piston accumulator to the current load state of the electronic control device ( 60 ) in a first step, the first control valve ( 50 ) into the third control position ( 50c ) and the second control valve ( 55 ) in the second control position ( 55b ) is actuated, in a second step, the first control valve ( 50 ) in the second control position ( 50b ) and the second control valve ( 55 ) in the first control position ( 55a ) is pressed. Mobile work machine according to one of claims 16 to 27, characterized in that the electronic control device ( 60 ) the shock absorption by the double piston accumulator ( 31 ) and / or the pressure adjustment of the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) depending on the driving speed controls. Mobile work machine according to claim 28, characterized in that the electronic control device ( 60 ) is designed such that when falling below a Grenzfahrgeschwindigkeit the shock absorption by the double piston accumulator ( 31 ) is deactivated and an adjustment of the gas pressure in the prestressing space ( 31a ) of the double piston accumulator ( 31 ) and the shock absorption by the double piston accumulator ( 31 ) is activated.

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