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WO2001045997A1 - Hydraulic system, particularly a steering device for an articulated vehicle - Google Patents

Hydraulic system, particularly a steering device for an articulated vehicle Download PDF

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Publication number
WO2001045997A1
WO2001045997A1 PCT/DK2000/000706 DK0000706W WO0145997A1 WO 2001045997 A1 WO2001045997 A1 WO 2001045997A1 DK 0000706 W DK0000706 W DK 0000706W WO 0145997 A1 WO0145997 A1 WO 0145997A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
motor
allocated
control
tank
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DK2000/000706
Other languages
French (fr)
Inventor
Jens Bjerregaard
Svend Erik Thomsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Danfoss Power Solutions ApS
Danfoss Power Solutions Holding ApS
Original Assignee
Sauer Danfoss Holding ApS
Sauer Danfoss Nordborg ApS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sauer Danfoss Holding ApS, Sauer Danfoss Nordborg ApS filed Critical Sauer Danfoss Holding ApS
Priority to AU21511/01A priority Critical patent/AU2151101A/en
Publication of WO2001045997A1 publication Critical patent/WO2001045997A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D12/00—Steering specially adapted for vehicles operating in tandem or having pivotally connected frames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/061—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle provided with effort, steering lock, or end-of-stroke limiters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/08—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of steering valve used
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/09—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by means for actuating 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
    • F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and 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
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/351—Flow control by regulating means in feed line, i.e. meter-in 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
    • F15B2211/50—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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5159—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a return line
    • 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6336—Electronic controllers using input signals representing a state of the output member, e.g. position, speed or acceleration
    • 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
    • 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
    • F15B2211/76—Control of force or torque of the output member
    • 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
    • F15B2211/78—Control of multiple output members
    • F15B2211/781—Control of multiple output members one or more output members having priority

Definitions

  • Hydraulic system particularly a steering device for an articulated vehicle
  • the invention concerns a hydraulic system, particularly a steering device for an articulated vehicle, with a pump, a tank, a control device and at least one motor connected with this control device via two motor lines, at least one stop device, which is activated on each reaching of an end position, and is allocated to the motor line being on the return side in this case, a control pressure system influencing the fluid pressure to be led to the control device and at least one normally closed non-return valve, which connects the control pressure system with the tank on acti- vation of the stop device.
  • a stop device is needed to prevent the parts driven by the motor from passing certain end positions.
  • Typical examples are articulated vehicles, in which it is desired to prevent the two parts of the vehicle from getting in mechanical touch with each other. This is uncomfortable for the driver. Additionally, vehicle parts might be damaged by such collisions.
  • US 4,558,759 describes a stop device with which the steering wheel column of the vehicle is locked, when the end position is reached.
  • a hydraulic system as described in the introduction is known from US 5,117,935.
  • a non-return valve is oper- ated when the end position is reached, the valve connecting a control pressure system, here the load pressure sensing system, with the tank.
  • a control pressure system here the load pressure sensing system
  • this state is only permitted for a short while, as otherwise the pressure build-up in the system, which is required for a movement of the motor in the opposite direction, could not take place.
  • the operator is therefore merely advised that the end position has been reached. When he does not react, the operation of the motor can continue and the unwanted contact of the two vehicle parts may occur.
  • the invention is based on the task of providing a hydraulic system as described in the introduction, in which the pressure reduction in the end position can be maintained for a longer while, however enabling a quick pressure build-up when leaving the end position.
  • this task is solved in that means depending on the pressure in the allocated motor line are provided, which means increase the control pressure, when the control device is activated to take the motor away from the end position.
  • the control pressure drops to a low value with the consequence that also the control pressure supplied to the control device drops to a stand-by pressure.
  • the hydraulic system can remain in this state for as long as desired. A fixed and unique end position appears, in which a slip is practi- cally completely avoided.
  • the operator activates the control device in the opposite direction, the motor line allocated to the stop device, which was until now a return side motor line, becomes a forward motor line. It thus carries an increased pressure. This pressure is now utilised by the stressed means to increase the control pressure, that is, to revert to the normal operating conditions .
  • a preferred embodiment provides that an activation of the stop device will cause each non-return valve to connect the allocated motor line with the control pressure system.
  • the pressure in the control pressure system is low, and the pressure supplied to the control device is reduced to the stand-by pressure mentioned.
  • the motor is moved in the opposite direction by a corresponding activation of the control device, the motor line in the control device being return side until now, becomes a forward motor line, whose pressure continues to prevail over the non- return valve in the control pressure system, so that a relatively quick pressure build-up is achieved.
  • a further preferred alternative provides that an activation of the allocated stop device will cause each non-return valve to connect the control pressure system with the tank, the non-return valve being arranged in series with a normally open additional valve, which closes at increased pressure in the allocated motor line.
  • the reduction of the control pressure endeavoured because of the stand- still of the motor is caused by the control pressure system being connected with the tank via the non-return valve.
  • the additional valve then overrules this non-return function of the non-return valve, so that an operation of the control device in the opposite direction will cause the control pressure to quickly assume the value required for the nor ⁇ mal operation.
  • An advantageous embodiment provides that on activation of the allocated stop device each non-return valve connects the control pressure system with the tank, that the nonreturn valves have an additional pressure inlet for the pressure in the allocated motor line and close at increased pressure. With the additional pressure inlet, the pressure in the motor line allocated to the stop device can be activated, which again enables an overruling of the opening function of the non-return valve.
  • an electrical switch is allocated to the end position and that the non-return valve is a solenoid valve.
  • An electrical switch of this kind is pre- ferred, as it will be sufficient to provide easily run electrical cables additionally to the hydraulic lines.
  • a control pressure dependent priority valve is inserted between the pump and the control device.
  • the priority valve supplies the motor with the quantity it requires, while the remaining output of the pump is led into a branch, which may comprise additional consumers.
  • the first motor reaching its end position does not influence the additional consumers.
  • Fig. 1 a steering device for an articulated vehicle ac- cording to the invention, shown as a line diagram
  • Fig. 2 a section of the line diagram of a second embodiment
  • Fig. 3 a section of the line diagram of a third embodiment Fig. 1 shows a control device 1, here a steering unit, having a rotatable steering shaft 2, a pump connection P for a pump line 3, a tank connection T for a tank line 4, two motor connections L and R for motor lines 5 and 6, as well as a control pressure connection LS for a control pressure system 7. These connections are connected with corresponding connections P' , T' , L' , R, and LS' of a module 8.
  • This module merely contains a schematically shown flow amplifier 9, which is connected with the lines 3, 4, 5 and 6 and has outlet lines 10 and 11, which carry the outlet connections CL and CR, to which the steering motor 12, having two cylinders 13 and 14, can be connected.
  • the motor lines 5 and 6 carry a pressure P R and P L , respectively, which is low, for example tank pressure level, in the return side motor line, and increased in the forward side motor line.
  • a pump 15 with a constant capacity supplies a priority valve 16, to whose priority outlet the pump line 3 is connected.
  • the priority valve is operated in dependence of the difference between the pump pressure led to the connection PP via a line 17 and the control pressure taken from the control device 1, which is passed on through the control pressure system 7.
  • the pressure fluid quantity, which is not required, is led via a branch line 18 to a connection EF and then either direct or via one or more consumers 19 to the tank 20.
  • the tank line 4 in the module 8 leads to a tank connection HT, to which the tank 20 is connected.
  • the motor 12 activates an electric switch 21 or 22, respectively.
  • the switch 21 sends an electrical signal to a non-return valve 23, which connects the control pressure system 7 with the allocated, presently return side, motor line 6.
  • the non- return valve 24 is activated and opens the connection between the control pressure system 7 and the motor line 5 then being the return line.
  • the tank pressure ruling in the return side motor line acts upon the priority valve 16, so that the priority valve reduces the pressure in the pump line 3 to a standby pressure of, for example, 10 bar.
  • the remaining consumers 19 can still be operated in the usual way. The hydraulic losses are minimal.
  • the end position can be maintained for as long as desired.
  • a throttle 25 is inserted, which ensures that an activation of the non-return valves 23 and 24 will not cause the pressure to increase and de- crease abruptly, but eventually.
  • An additional throttle may be provided in the control device 1.
  • the hydraulic system also works without such throttles.
  • control pressure is decisive for the size of the fluid pressure to the control device.
  • the control device 1 can have any desired, known shape, for example, it can be a Danfoss steering unit type OSPB, OSPC or OSPF.
  • the module 8 is known, for example, under the name OSQA or OSQB from the company Danfoss A/S.
  • the control pressure system 107 is connected with the tank 120 via two lines 126 and 127.
  • the line 126 has a non-return valve 124, which opens when the electric switch 122 signalises the end position of the motor.
  • the second line 127 which has the series connection of the non-return valve 123, which can be activated by the electric switch 121, and an additional valve 129, which is brought to the blocking position by an increased pressure P L in the left motor line.
  • the hydraulic system is not only suited for articulated or artic-frame vehicles, but can be used anywhere, where a motor needs an end position limitation to prevent it from striking a fixed counter flange.
  • the flow amplifier 9 is no compulsory feature.
  • the pump 15 can also be a variable pump, whose capacity depends on the control pressure.
  • the non-return valves 23, 123, 223, 24, 124, 224 are shown as solenoid valves being activated by means of the switches 21 and 22.
  • the non-return valves 23 and 24 can also be arranged immediately next to the motor and be direct mechanically activated. Also the use of any other known proximity switch is possible.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

A hydraulic system, particularly a steering device for an articulated vehicle, has a pump (15), a tank (20), a control device (1) and at least one motor (12) connected with the control device via two motor lines (5, 6). There is at least one stop device, which is activated when reaching one of the end positions, and which is allocated to the return side motor line, a control pressure system (7) influencing the pressure supplied to the control pressure (LS) and at least one normally closed non-return valve (23, 24), which connects the control pressure system (7) with the tank (20), when the stop device is activated. Further, means depending on the pressure (PR, PL) in the allocated motor line (5, 6) are provided, which increase the control pressure (LS) when the control device (1) is activated to take the motor (12) away from the end position. Thus, the motor (12) is stopped in the end positions. When a motor movement in the opposite direction is initiated, the full pump pressure is built up very quickly.

Description

Hydraulic system, particularly a steering device for an articulated vehicle
The invention concerns a hydraulic system, particularly a steering device for an articulated vehicle, with a pump, a tank, a control device and at least one motor connected with this control device via two motor lines, at least one stop device, which is activated on each reaching of an end position, and is allocated to the motor line being on the return side in this case, a control pressure system influencing the fluid pressure to be led to the control device and at least one normally closed non-return valve, which connects the control pressure system with the tank on acti- vation of the stop device.
In many hydraulic systems, a stop device is needed to prevent the parts driven by the motor from passing certain end positions. Typical examples are articulated vehicles, in which it is desired to prevent the two parts of the vehicle from getting in mechanical touch with each other. This is uncomfortable for the driver. Additionally, vehicle parts might be damaged by such collisions.
US 4,558,759 describes a stop device with which the steering wheel column of the vehicle is locked, when the end position is reached.
US 3,993,158 describes a stop device with a normally closed non-return valve which is activated when getting close to the end position, thus connecting the pump pressure line with the tank. However, this causes substantial energy losses .
A hydraulic system as described in the introduction is known from US 5,117,935. Here, a non-return valve is oper- ated when the end position is reached, the valve connecting a control pressure system, here the load pressure sensing system, with the tank. However, this state is only permitted for a short while, as otherwise the pressure build-up in the system, which is required for a movement of the motor in the opposite direction, could not take place. The operator is therefore merely advised that the end position has been reached. When he does not react, the operation of the motor can continue and the unwanted contact of the two vehicle parts may occur.
The invention is based on the task of providing a hydraulic system as described in the introduction, in which the pressure reduction in the end position can be maintained for a longer while, however enabling a quick pressure build-up when leaving the end position.
According to the invention, this task is solved in that means depending on the pressure in the allocated motor line are provided, which means increase the control pressure, when the control device is activated to take the motor away from the end position.
When the stop device activates the non-return valve, the control pressure drops to a low value with the consequence that also the control pressure supplied to the control device drops to a stand-by pressure. The hydraulic system can remain in this state for as long as desired. A fixed and unique end position appears, in which a slip is practi- cally completely avoided. When, however, the operator activates the control device in the opposite direction, the motor line allocated to the stop device, which was until now a return side motor line, becomes a forward motor line. It thus carries an increased pressure. This pressure is now utilised by the stressed means to increase the control pressure, that is, to revert to the normal operating conditions .
A preferred embodiment provides that an activation of the stop device will cause each non-return valve to connect the allocated motor line with the control pressure system. As the return side motor line is connected with the tank, the pressure in the control pressure system is low, and the pressure supplied to the control device is reduced to the stand-by pressure mentioned. When, later, the motor is moved in the opposite direction by a corresponding activation of the control device, the motor line in the control device being return side until now, becomes a forward motor line, whose pressure continues to prevail over the non- return valve in the control pressure system, so that a relatively quick pressure build-up is achieved.
A further preferred alternative provides that an activation of the allocated stop device will cause each non-return valve to connect the control pressure system with the tank, the non-return valve being arranged in series with a normally open additional valve, which closes at increased pressure in the allocated motor line. Here, the reduction of the control pressure endeavoured because of the stand- still of the motor is caused by the control pressure system being connected with the tank via the non-return valve. The additional valve then overrules this non-return function of the non-return valve, so that an operation of the control device in the opposite direction will cause the control pressure to quickly assume the value required for the nor¬ mal operation.
An advantageous embodiment provides that on activation of the allocated stop device each non-return valve connects the control pressure system with the tank, that the nonreturn valves have an additional pressure inlet for the pressure in the allocated motor line and close at increased pressure. With the additional pressure inlet, the pressure in the motor line allocated to the stop device can be activated, which again enables an overruling of the opening function of the non-return valve.
It is advantageous that an electrical switch is allocated to the end position and that the non-return valve is a solenoid valve. An electrical switch of this kind is pre- ferred, as it will be sufficient to provide easily run electrical cables additionally to the hydraulic lines. However, it is also possible to use a purely mechanical solution, in which the non-return valve is brought to its open position direct by the connecting rod of the motor.
In a preferred embodiment, it is provided that a control pressure dependent priority valve is inserted between the pump and the control device. Here, the priority valve supplies the motor with the quantity it requires, while the remaining output of the pump is led into a branch, which may comprise additional consumers. With this embodiment the first motor reaching its end position does not influence the additional consumers.
In the following, the invention is described in detail on the basis of preferred embodiments in connection with the drawings, showing:
Fig. 1 a steering device for an articulated vehicle ac- cording to the invention, shown as a line diagram
Fig. 2 a section of the line diagram of a second embodiment
Fig. 3 a section of the line diagram of a third embodiment Fig. 1 shows a control device 1, here a steering unit, having a rotatable steering shaft 2, a pump connection P for a pump line 3, a tank connection T for a tank line 4, two motor connections L and R for motor lines 5 and 6, as well as a control pressure connection LS for a control pressure system 7. These connections are connected with corresponding connections P' , T' , L' , R, and LS' of a module 8. This module merely contains a schematically shown flow amplifier 9, which is connected with the lines 3, 4, 5 and 6 and has outlet lines 10 and 11, which carry the outlet connections CL and CR, to which the steering motor 12, having two cylinders 13 and 14, can be connected. The motor lines 5 and 6 carry a pressure PR and PL, respectively, which is low, for example tank pressure level, in the return side motor line, and increased in the forward side motor line.
A pump 15 with a constant capacity supplies a priority valve 16, to whose priority outlet the pump line 3 is connected. The priority valve is operated in dependence of the difference between the pump pressure led to the connection PP via a line 17 and the control pressure taken from the control device 1, which is passed on through the control pressure system 7. The pressure fluid quantity, which is not required, is led via a branch line 18 to a connection EF and then either direct or via one or more consumers 19 to the tank 20. The tank line 4 in the module 8 leads to a tank connection HT, to which the tank 20 is connected.
In both end positions, the motor 12 activates an electric switch 21 or 22, respectively. The switch 21 sends an electrical signal to a non-return valve 23, which connects the control pressure system 7 with the allocated, presently return side, motor line 6. In the same way, when at the end of the movement path the switch 24 is activated, the non- return valve 24 is activated and opens the connection between the control pressure system 7 and the motor line 5 then being the return line.
As soon as one of the non-return valves 23 or 24 is activated, the tank pressure ruling in the return side motor line acts upon the priority valve 16, so that the priority valve reduces the pressure in the pump line 3 to a standby pressure of, for example, 10 bar. In this situation, the remaining consumers 19 can still be operated in the usual way. The hydraulic losses are minimal. The end position can be maintained for as long as desired.
When now, in the control device, the steering handwheel is turned in the opposite direction, the motor line 6, still connected with the control pressure system 7, carries a higher pressure and no longer the tank pressure. This immediately influences the priority valve, which leads to a quick pressure increase, as desired. Therefore, the hydrau- lie system is operational again immediately.
In the control pressure system 7 a throttle 25 is inserted, which ensures that an activation of the non-return valves 23 and 24 will not cause the pressure to increase and de- crease abruptly, but eventually. An additional throttle may be provided in the control device 1. However, the hydraulic system also works without such throttles.
Several embodiments of the control pressure system are possible, in which the control pressure is decisive for the size of the fluid pressure to the control device. This is particularly the case for static load pressure systems, as known from US 5,117,935, and also for dynamic control pressure systems as described in DE 43 42 933 C2. The control device 1 can have any desired, known shape, for example, it can be a Danfoss steering unit type OSPB, OSPC or OSPF. Also the module 8 is known, for example, under the name OSQA or OSQB from the company Danfoss A/S.
In relation to Fig. 1, the reference numbers for corresponding parts are increased by 100 in the circuit shown in Fig. 2. The control pressure system 107 is connected with the tank 120 via two lines 126 and 127. The line 126 has a non-return valve 124, which opens when the electric switch 122 signalises the end position of the motor. In series with the non-return valve is an additional valve 128, which closes under the influence of an increased pressure PR in the right motor line. When the end position is reached, the line 126 is therefore opened and closes again on an activation of the control device in the opposite direction, so that the control pressure LS can increase rapidly again. The same conditions apply for the second line 127, which has the series connection of the non-return valve 123, which can be activated by the electric switch 121, and an additional valve 129, which is brought to the blocking position by an increased pressure PL in the left motor line.
In the embodiment according to Fig. 3, reference numbers increased by 200 are used for corresponding parts. Here, the functions of the two series connected valves according to Fig. 2 are united in one modified non-return valve 223, 224. For this purpose, an additional pressure inlet 230, 231 is provided, which is supplied with the pressure PR in the right motor line or the pressure PL in the left motor line. When the pressure in the motor line is low, because the return side motor line is concerned, the non-return valve assumes the opening position on activation of one of the electric switches 221 or 222. When, on the other hand, the pressure in the allocated motor line increases, because the activation of the control device 1 makes it an inflow side motor line, the motor line pressure PR or P, respectively, overcomes the magnet forces and leads the nonreturn valve 223, 224 back into the blocking position.
The hydraulic system is not only suited for articulated or artic-frame vehicles, but can be used anywhere, where a motor needs an end position limitation to prevent it from striking a fixed counter flange.
Several variations with respect to the embodiment shown can be made, without deviating from the basic idea of the invention. For example, the flow amplifier 9 is no compulsory feature. The pump 15 can also be a variable pump, whose capacity depends on the control pressure. The non-return valves 23, 123, 223, 24, 124, 224 are shown as solenoid valves being activated by means of the switches 21 and 22. However, the non-return valves 23 and 24 can also be arranged immediately next to the motor and be direct mechanically activated. Also the use of any other known proximity switch is possible.

Claims

Patent Claims
1. Hydraulic system, particularly a steering device for an articulated vehicle, with a pump, a tank, a control device and at least one motor connected with this control device via two motor lines, at least one stop device, which is activated on each reaching of an end position, and is allocated to the motor line being on the return side in this case, a control pressure system influencing the fluid pressure to be led to the control device and at least one normally closed non-return valve, which connects the control pressure system with the tank on activation of the stop device, characterised in that means depending on the pressure (PR, PL) in the allocated motor line (5, 6) are provided, which means increase the control pressure (LS), when the control device (1) is activated to take the motor (12) away from the end position.
System according to claim 1, characterised in that an activation of the stop device will cause each nonreturn valve (23, 24) to connect the allocated motor line (5, 6) with the control pressure system.
3. System according to claim 1, characterised in that an activation of the allocated stop device will cause each non-return valve (123, 124) to connect the control pressure system (107) with the tank (120), the non- return valve being arranged in series with a normally open additional valve (128, 129), which closes at increased pressure (PR, PL) in the allocated motor line.
4. System according to claim 1, characterised in that on activation of the allocated stop device each non-return valve (223, 224) connects the control pressure system
(207) with the tank (220), that each non-return valve has an additional pressure inlet (230, 231) for the pressure (PR, PL) in the allocated motor line (5, 6) and closes at increased pressure.
5. System according to one of the claims 1 to 4, characterised in that an electrical switch (21, 22) is allocated to the end position and that the non-return valve (23, 24) is a solenoid valve.
6. System according to one of the claims 1 to 5, characterised in that a control pressure (LS) dependent priority valve (16) is inserted between the pump (15) and the control device (1) .
PCT/DK2000/000706 1999-12-20 2000-12-18 Hydraulic system, particularly a steering device for an articulated vehicle Ceased WO2001045997A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU21511/01A AU2151101A (en) 1999-12-20 2000-12-18 Hydraulic system, particularly a steering device for an articulated vehicle

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1999161891 DE19961891C2 (en) 1999-12-20 1999-12-20 Hydraulic system, in particular steering device for an articulated vehicle
DE19961891.7 1999-12-20

Publications (1)

Publication Number Publication Date
WO2001045997A1 true WO2001045997A1 (en) 2001-06-28

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DE (1) DE19961891C2 (en)
WO (1) WO2001045997A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11447374B2 (en) 2016-09-15 2022-09-20 Terex Australia Pty Ltd Crane counterweight and suspension

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3993158A (en) * 1975-01-03 1976-11-23 O & K Orenstein & Koppel Aktiengesellschaft Device for limiting in a contact-free manner the movement of hydraulically operable mechanical parts
US4558759A (en) * 1982-12-14 1985-12-17 Danfoss A/S Hydrostatic steering device steering wheel travel limits
US5117935A (en) * 1990-12-21 1992-06-02 Caterpillar Inc. Load sensing hydrostatic steering system
US5660096A (en) * 1992-12-11 1997-08-26 Danfoss A/S Controlled proportional valve

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4342933C2 (en) * 1993-12-16 1995-10-19 Danfoss As Device for controlling the pressure to be supplied to a hydrostatic steering unit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3993158A (en) * 1975-01-03 1976-11-23 O & K Orenstein & Koppel Aktiengesellschaft Device for limiting in a contact-free manner the movement of hydraulically operable mechanical parts
US4558759A (en) * 1982-12-14 1985-12-17 Danfoss A/S Hydrostatic steering device steering wheel travel limits
US5117935A (en) * 1990-12-21 1992-06-02 Caterpillar Inc. Load sensing hydrostatic steering system
US5660096A (en) * 1992-12-11 1997-08-26 Danfoss A/S Controlled proportional valve

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11447374B2 (en) 2016-09-15 2022-09-20 Terex Australia Pty Ltd Crane counterweight and suspension

Also Published As

Publication number Publication date
DE19961891A1 (en) 2001-06-28
DE19961891C2 (en) 2002-10-24
AU2151101A (en) 2001-07-03

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