WO2013145334A1 - ホイールローダのステアリング装置 - Google Patents
ホイールローダのステアリング装置 Download PDFInfo
- Publication number
- WO2013145334A1 WO2013145334A1 PCT/JP2012/060541 JP2012060541W WO2013145334A1 WO 2013145334 A1 WO2013145334 A1 WO 2013145334A1 JP 2012060541 W JP2012060541 W JP 2012060541W WO 2013145334 A1 WO2013145334 A1 WO 2013145334A1
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- WO
- WIPO (PCT)
- Prior art keywords
- steering
- valve
- control valve
- lever
- handle
- Prior art date
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/225—Control of steering, e.g. for hydraulic motors driving the vehicle tracks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
- B62D1/22—Alternative steering-control elements, e.g. for teaching purposes
-
- 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
- B62D5/07—Supply of pressurised fluid for steering also supplying other consumers ; control thereof
- B62D5/075—Supply of pressurised fluid for steering also supplying other consumers ; control thereof using priority valves
-
- 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
-
- 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
- B62D5/091—Hydraulic steer-by-wire systems, e.g. the valve being actuated by an electric motor
-
- 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
- B62D5/10—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 power unit
- B62D5/12—Piston and cylinder
-
- 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
- B62D5/18—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 power transmitting means
-
- 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
- B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
-
- 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
- B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
- B62D5/28—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for pivoted bogies
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/08—Superstructures; Supports for superstructures
- E02F9/0841—Articulated frame, i.e. having at least one pivot point between two travelling gear units
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2296—Systems with a variable displacement pump
Definitions
- the present invention relates to a steering device, and more particularly to a steering device for a wheel loader in which a front frame and a rear frame are connected so as to be rotatable in a horizontal direction.
- the wheel loader is provided with a handle for performing a steering operation during traveling on a public road or at a high speed on a work site. Further, in a work site where a short distance traveling and a steering operation are repeated, a lever such as a joystick is provided so that an efficient steering operation can be performed with a simple operation.
- the steering operation may be performed unintentionally.
- the control device for a cargo handling machine disclosed in Patent Document 1 is configured such that when the handle and the lever are operated simultaneously, the handle operation is given priority.
- a sequence valve is provided along with a control valve for lever operation. When the steering wheel is operated, the sequence valve is acted by the hydraulic fluid flowing through the steering valve, so that the supply of hydraulic fluid from the lever control valve to the steering cylinder is shut off. It has become.
- An object of the present invention is to realize a mechanism for giving priority to steering operation in a wheel loader that enables steering operation by steering operation and lever operation, and to operate the mechanism stably.
- a steering device for a wheel loader includes a handle that is rotated for steering, a lever that is tilted for steering, and a front frame that rotates relative to a rear frame by extending and contracting.
- a steering cylinder for moving, a steering valve, a pump, a handle control valve, a lever electromagnetic control valve, and a handle priority valve are provided.
- the steering valve controls the supply direction of hydraulic oil to the steering cylinder by pilot hydraulic pressure.
- the pump supplies hydraulic oil to the steering cylinder via the steering valve.
- the handle control valve supplies pilot hydraulic pressure for supply direction control to the steering valve by rotating the handle.
- the electromagnetic control valve for lever supplies pilot hydraulic pressure for supply direction control to the steering valve by tilting operation of the lever.
- the handle priority valve shuts off the pilot hydraulic pressure supplied from the electromagnetic control valve for the lever to the steering valve by the differential pressure or absolute pressure of the hydraulic circuit generated when hydraulic oil flows through the handle control valve when the handle is operated. To do.
- pilot hydraulic pressure for controlling the supply direction of hydraulic oil is supplied to the steering valve via the handle control valve.
- pilot hydraulic pressure for controlling the supply direction of hydraulic oil is supplied to the steering valve via the lever electromagnetic control valve.
- the handle is operated, the hydraulic oil flows through the handle control valve, so that the handle priority valve is operated by the differential pressure or absolute pressure of the hydraulic circuit through which the hydraulic oil flows.
- the pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve is shut off.
- the handle when the handle is operated, even if the lever is operated during the handle operation, the pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve is cut off and the handle operation is given priority. Therefore, even when the driver accidentally touches the lever during the steering operation, it is possible to prevent an unintended steering operation from being performed. Moreover, since the pilot hydraulic pressure from the lever electromagnetic control valve is shut off by the handle priority valve that operates with the differential pressure or absolute pressure of the hydraulic circuit generated by the handle operation, the circuit configuration is simplified, and the operation of the handle priority valve is simplified. Can be prevented from becoming unstable.
- the steering device for a wheel loader is the steering device according to the first aspect, wherein the handle priority valve is prioritized with a first throttle provided in the middle of a circuit that supplies hydraulic oil to the handle control valve. And a valve body.
- the priority valve body has a communication stage for supplying pilot hydraulic pressure from the lever electromagnetic control valve to the steering valve, and a shut-off stage for blocking supply of pilot hydraulic pressure to the steering valve. When a differential pressure occurs, it is switched to the cutoff stage.
- the steering operation can be surely prioritized with a simple configuration.
- a steering device for a wheel loader is the steering device according to the second aspect, wherein the handle priority valve is provided in the middle of a circuit for supplying hydraulic oil to the lever electromagnetic control valve.
- a second diaphragm having a small diameter is further provided.
- the steering wheel operation is given priority even when the priority valve body does not operate normally.
- a second throttle having a throttle diameter smaller than that of the first throttle on the handle control valve side is provided in the middle of the circuit for supplying the hydraulic oil to the lever electromagnetic control valve.
- the first throttle has a relatively large throttle diameter
- the second throttle has a relatively small throttle diameter.
- a lot of hydraulic oil is supplied to the control valve side, and the steering operation is prioritized.
- the steering device for the wheel loader opens in the second or third aspect device in parallel with the first throttle when the differential pressure before and after the first throttle becomes equal to or higher than a predetermined pressure.
- the operation oil is further supplied to the handle control valve, and a check valve for stopping the operation oil flowing backward from the handle control valve is further provided.
- a check valve is provided in parallel with the first throttle. Therefore, when the pressure difference necessary for operating the priority valve main body is exceeded, the check valve is opened, and an increase in pressure loss at a large flow rate is suppressed. Even if the first throttle is clogged, if the circuit pressure becomes equal to or higher than a predetermined pressure, the hydraulic oil is supplied to the handle control valve via the check valve.
- a steering device for a wheel loader further includes a left pilot oil passage and a right pilot oil passage provided between the steering control valve and the steering valve in the first side device.
- the handle priority valve has a priority control valve and a switching valve.
- the priority control valve is arranged between the steering control valve and the electromagnetic control valve for the lever and the steering valve, and communicates the steering control valve and the steering valve and shuts off the electromagnetic control valve for the lever and the steering valve.
- a handle stage, and a lever stage that blocks the handle control valve and the steering valve and communicates the lever electromagnetic control valve and the steering valve.
- the switching valve switches the priority control valve to the handle stage when a differential pressure is generated between the left pilot oil passage and the right pilot oil passage.
- the handle operation is given priority in a stable and reliable manner.
- a steering device for a wheel loader is the pilot oil passage for the left lever and the pilot oil for the right lever provided between the lever electromagnetic control valve and the priority control valve.
- the road is further provided.
- the switching valve switches the priority control valve to the lever stage when there is no differential pressure between the left pilot oil passage and the right pilot oil passage and a differential pressure is generated between the left and right lever pilots.
- the steering operation can be reliably performed by the lever operation.
- a steering device for a wheel loader further includes a left pilot oil passage and a right pilot oil passage provided between the steering control valve and the steering valve in the first side device.
- the steering wheel priority valve has a priority control valve and a switching valve.
- the priority control valve is arranged between the steering control valve and the electromagnetic control valve for the lever and the steering valve, and communicates the steering control valve and the steering valve and shuts off the electromagnetic control valve for the lever and the steering valve.
- a handle stage, and a lever stage that blocks the handle control valve and the steering valve and communicates the lever electromagnetic control valve and the steering valve.
- the switching valve switches the priority control valve to the handle stage when hydraulic oil flows into the handle control valve, and switches the priority control valve to the lever stage when hydraulic oil flows only into the lever electromagnetic control valve.
- the priority control valve when the handle is operated, the hydraulic oil flows into the left pilot oil passage or the right pilot oil passage via the handle control valve. In response to the flow of the hydraulic oil, the priority control valve is switched to the handle stage by the switching valve. Further, when only the lever is operated and hydraulic fluid flows only to the lever electromagnetic control valve, the priority control valve is switched to the lever stage by the switching valve.
- a steering device for a wheel loader includes a left pilot oil passage and a right pilot oil passage provided between a steering control valve and a steering valve, and a steering valve in the first side device. And a return oil passage for guiding the return oil to the tank via the handle control valve.
- the output port of the lever electromagnetic control valve is connected to the left and right pilot oil passages.
- the handle priority valve has a throttle and a priority valve body. The throttle is provided between the handle control valve and the tank in the return oil passage.
- the priority valve body is provided between the output port of the electromagnetic control valve for the lever and the left and right pilot oil passages, and a communication stage for communicating the output port of the electromagnetic control valve for the lever and the left and right pilot oil passages.
- a shut-off stage that shuts off between the output port of the electromagnetic control valve and the left and right pilot oil passages.
- the priority valve body is switched to the shut-off stage when a differential pressure is generated before and after the throttle, and is switched to the communication stage when there is no differential pressure before and after the throttle.
- the handle when the handle is operated, the hydraulic oil is returned from the steering valve to the tank via the handle control valve. Therefore, a differential pressure is generated before and after the throttle provided in the return oil passage.
- the priority valve body is switched to the cutoff stage. Therefore, the hydraulic oil from the lever electromagnetic control valve is not supplied to the steering valve. That is, the steering wheel operation has priority.
- the priority valve body is switched to the communication stage. Therefore, the hydraulic oil from the lever electromagnetic control valve is supplied to the steering valve via the left pilot oil passage or the right pilot oil passage, and the steering operation by the lever operation becomes possible.
- a steering device for a wheel loader is the apparatus of the eighth aspect, wherein the steering device is provided in parallel with the throttle and opens when the differential pressure before and after the throttle exceeds a predetermined pressure and tanks the hydraulic oil. It is further provided with a check valve for returning to.
- the check valve opens and the increase in pressure loss at a large flow rate is suppressed.
- the hydraulic oil is returned from the handle control valve side to the tank side via the check valve. This prevents the handle from becoming inoperable.
- a mechanism for prioritizing steering operation can be realized with a simple configuration, and priority is given to steering operation by stable operation. Can be executed reliably.
- the figure which shows the external appearance structure of a wheel loader The figure which shows the system configuration
- FIG. 1 shows an overall configuration of a wheel loader 1 on which a steering device according to a first embodiment of the present invention is mounted.
- FIG. 1 is a side view of the wheel loader 1.
- the wheel loader 1 includes a body frame 2, a work machine 3, a pair of front tires 4, a driver's cab 5, an engine room 6, and a pair of rear tires 7.
- the body frame 2 has a so-called articulate structure, and includes a front frame 11, a rear frame 12, and a connecting portion 13.
- the front frame 11 is disposed in front of the rear frame 12, and is connected to the rear frame 12 by a connecting portion 13 so as to be rotatable in the left-right direction.
- the work machine 3 has a lift arm 15 and a bucket 16.
- the lift arm 15 and the bucket 16 are driven by pressure oil supplied from a hydraulic pump (not shown).
- the lift arm 15 has a base end rotatably supported by the front frame 11.
- the bucket 16 is rotatably attached to the tip end portion of the lift arm 15.
- the cab 5 is placed on the rear frame 12, and a steering wheel and joystick, operation members for operating the work machine, various display devices, and the like are disposed therein.
- FIG. 2 shows the configuration of the steering device 20.
- the steering device 20 is a device for turning the vehicle by turning the front frame 11 with respect to the rear frame 12.
- the steering device 20 has a handle 21 that is rotated, a joystick 22 that is tilted, and left and right steering cylinders 23L and 23R.
- the handle 21 and the joystick 22 are members that are operated for steering. By operating these members 21 and 22, the left and right steering cylinders 23L and 23R expand and contract, and the front frame 11 rotates with respect to the rear frame 12.
- the steering device 20 includes a steering valve 25, an orbit roll 26 as a handle control valve, a lever electromagnetic control valve 27, and a handle priority valve 28.
- ⁇ Steering valve 25> The steering valve 25 supplies hydraulic oil from the pump 30 to one of the left and right steering cylinders 23L and 23R in accordance with the pilot hydraulic pressure from the orbit roll 26 or the lever electromagnetic control valve 27.
- the direction control valve 25a constituting the steering valve 25 is switched to the left turning stage L when hydraulic oil is supplied to the left pilot port, and is turned right when hydraulic oil is supplied to the right pilot port. Switch to stage R.
- the direction control valve 25a is switched to the left turning stage L, the hydraulic oil from the pump 30 is supplied to the bottom side oil chamber of the left steering cylinder 23L and the rod side oil chamber of the right steering cylinder 23R, and the bottom of the right steering cylinder 23R.
- the hydraulic oil in the side oil chamber and the rod side oil chamber of the left steering cylinder 23L is returned to the tank 31 via the drain oil passage Pd.
- both pilot ports of the directional control valve 25a are communicated with each other through a throttle 25b.
- the hydraulic fluid in the other pilot port side oil passage is returned to the tank 31 via the orbit roll 26 and the drain oil passage Pd.
- the steering valve 25 includes an unload valve, a relief valve, a safety valve, and the like in addition to the directional control valve 25a.
- the orbit roll 26 has an input-side P port connected to a pilot hydraulic pump (not shown) such as a fan pump via a first input oil passage P01.
- the orbit roll 26 discharges hydraulic oil proportional to the amount of handle rotation from the L port when the handle 21 is rotated counterclockwise, and from the R port when the handle 21 is rotated clockwise.
- the left pilot oil passage PL is connected to the L port on the output side, and the right pilot oil passage PR is connected to the R port.
- the left pilot oil passage PL is connected to the left pilot port of the directional control valve 25a constituting the steering valve 25. Further, the right pilot oil passage PR is connected to the right pilot port of the direction control valve 25a. Stop valves 34 and 35 are provided in the left and right pilot oil passages PL and PR, respectively. These stop valves 34 and 35 forcibly stop the supply of pilot hydraulic pressure to the steering valve 25.
- the input side T port of the orbit roll 26 is connected to the tank 31 via the drain oil passage Pd.
- the other pilot port side oil passage is connected to the drain oil passage Pd via this T port.
- the lever electromagnetic control valve 27 has an input-side P port connected via a second input oil passage P02 to a pump to which the first input oil passage P01 is connected.
- the lever electromagnetic control valve 27 discharges hydraulic oil input from the P port to the L port or R port on the output side in accordance with the operation of the joystick 22.
- the left lever pilot oil passage PLl is connected to the L port, and the left lever pilot oil passage PLl is connected to the left pilot oil passage PL.
- the right lever pilot oil passage PRl is connected to the R port, and the right lever pilot oil passage PRl is connected to the right pilot oil passage PR.
- a handle priority valve 28 is provided in the left lever pilot oil passage PLl and the right lever pilot oil passage PRl.
- the hydraulic oil from the lever electromagnetic control valve 27 is supplied to each pilot port of the steering valve 25 via the handle priority valve 28 and the left and right pilot oil paths PL and PR.
- the handle priority valve 28 includes a priority valve main body 40, a first throttle 41, a check valve 42, and a second throttle 43.
- the priority valve body 40 is provided in the middle of the left and right lever pilot oil passages PLl and PRl on the output side of the lever electromagnetic control valve 27.
- the priority valve main body 40 is switched between the communication stage St and the cutoff stage Sb by the pilot hydraulic pressure before and after the first throttle 41.
- the first throttle valve 41 is provided in the first input oil passage P01.
- the check valve 42 is provided in parallel to the first throttle 41, and when the differential pressure before and after the first throttle 41 becomes equal to or higher than a predetermined pressure, the hydraulic oil from the first input oil passage P01 is supplied to the orbit roll 26. Supply.
- the second throttle 43 is provided in the second input oil passage P02, and the throttle diameter is set smaller than that of the first throttle 41.
- a filter 44 is provided on the input side of the second diaphragm 43.
- the priority valve main body 40 when the pilot hydraulic pressure is not applied to the priority valve main body 40, the priority valve main body 40 is switched to the communication stage St by a spring. On the other hand, when the hydraulic oil flows through the first throttle 41 and the hydraulic pressure on the input side of the first throttle 41 becomes higher than that on the output side, the priority valve body 40 is switched to the cutoff stage Sb.
- FIG. 3 shows the flow of the steering hydraulic oil (solid line) and the pilot hydraulic oil (broken line) when the steering wheel is operated for turning to the left.
- the pilot hydraulic oil is input to the orbit roll 26 from the first input oil passage P01. That is, the hydraulic oil passes through the first throttle 41. For this reason, the oil pressure on the input side of the first throttle 41 is higher than the oil pressure on the output side. For this reason, the priority valve body 40 is switched to the cutoff stage Sb.
- the hydraulic oil input from the first input oil passage P01 is output from the orbit roll 26 to the left pilot oil passage PL.
- This hydraulic oil is input to the left pilot port of the direction control valve 25a of the steering valve 25 via the stop valve 35.
- the direction control valve 25a is switched to the left turn stage L by this pilot hydraulic pressure.
- the check valve 42 is opened to suppress an increase in differential pressure, that is, an increase in pressure loss. Further, when the first throttle 41 is clogged during the steering operation, the hydraulic pressure in the first input oil passage P01 increases. When this hydraulic pressure becomes equal to or higher than a predetermined hydraulic pressure, the check valve 42 is opened and hydraulic oil is supplied to the orbit roll 26.
- the hydraulic oil input from the second input oil path P02 is output from the joystick 22 to the left lever pilot oil path PLl.
- This hydraulic oil is supplied to the left pilot oil passage PL, and is input to the left pilot port of the direction control valve 25a of the steering valve 25 as in the case of the steering operation described above. Therefore, the direction control valve 25a is switched to the left turn stage L. Further, the pilot oil in the right pilot oil passage PR is returned from the tank port T of the lever electromagnetic control valve 27 to the tank 31 through the drain oil passage Pd.
- the diameter of the first diaphragm 41 on the handle operating side is set larger than the diameter of the second diaphragm 43 on the joystick operating side. Therefore, even when the priority valve main body 40 does not normally operate, more hydraulic oil is supplied to the orbit roll 26 and the steering operation is prioritized.
- a check valve 42 is provided in parallel with the first throttle 41, and hydraulic oil is supplied to the orbit roll 26 via the check valve 42 when the differential pressure before and after the first throttle 41 becomes a predetermined pressure or more. . Therefore, when a large flow rate of hydraulic oil is supplied to the first throttle 41, the hydraulic oil flows through the check valve 42, and an increase in pressure loss is suppressed. Further, even when the first diaphragm 41 is clogged, the handle operation can be made effective.
- FIG. 5 shows a steering apparatus according to a second embodiment of the present invention.
- This steering device is different from the first embodiment only in the steering wheel priority valve 50, and other configurations are the same as those in the first embodiment.
- the handle priority valve 50 different from the first embodiment will be described.
- the steering wheel priority valve 50 includes a priority control valve 51 provided in the middle of the left and right pilot oil paths PL and PR, and a switching valve 52 that switches the priority control valve 51.
- ⁇ Priority control valve 51> The left and right output ports of the orbit roll 26 are connected to the input port of the priority control valve 51 via the left and right pilot oil passages PL and PR. Further, the left and right output ports of the lever electromagnetic control valve 27 are connected to the other input ports of the priority control valve 51. The input port of the priority control valve 51 and the left and right output ports of the lever electromagnetic control valve 27 are connected by a left lever pilot oil passage PLl and a right lever pilot oil passage PRl.
- the priority control valve 51 is switched between the steering wheel stage Sh and the lever stage Sl by the pilot hydraulic pressure from the switching valve 52. Specifically, when the pilot hydraulic pressure is not supplied, the operation is switched to the handle stage Sh, and when the pilot hydraulic pressure is supplied from the switching valve 52, the operation is switched to the lever stage Sl.
- the orbit roll 26 and the steering valve 25 are communicated with each other and the lever electromagnetic control valve 27 and the steering valve 25 are blocked.
- the orbit roll 26 and the steering valve 25 are disconnected from each other, and the lever electromagnetic control valve 27 and the steering valve 25 are communicated with each other.
- the switching valve 52 is a valve for switching the priority control valve 51 between the handle stage Sh and the lever stage Sl.
- the pilot port of the switching valve 52 is supplied with hydraulic pressures of the left and right pilot oil passages PL and PR.
- the switching stage 52 is switched to the shut-off stage Sb.
- the left and right pilot oil passages PL1 and PR1 are connected to the input port of the switching valve 52 via the shuttle valve 54.
- the output port of the switching valve 52 is connected to the pilot port of the priority control valve 51.
- FIG. 6 shows the flow of the steering hydraulic oil (solid line) and the pilot hydraulic oil (broken line) when the steering wheel is operated for turning to the left.
- the hydraulic oil input from the first input oil passage P01 is output from the orbit roll 26 to the left pilot oil passage PL.
- This hydraulic oil is input to the left pilot port of the direction control valve 25a of the steering valve 25 via the stop valve 35.
- the direction control valve 25a is switched to the left turn stage L by this pilot hydraulic pressure.
- the hydraulic oil flows through the left lever pilot oil passage PL1, and this hydraulic oil is input to the switching valve 52 via the shuttle valve 54. Since the switching valve 52 is switched to the communication stage St, the input hydraulic oil is input to the pilot port of the priority control valve 51. For this reason, the priority control valve 51 is switched to the lever stage S1.
- the hydraulic oil input from the second input oil path P02 is output from the joystick 22 to the left lever pilot oil path PLl.
- This hydraulic oil is supplied to the left pilot oil passage PL via the priority control valve 51, and is input to the left pilot port of the direction control valve 25a of the steering valve 25 as in the case of the steering operation described above. Therefore, the direction control valve 25a is switched to the left turn stage L. Further, the hydraulic oil in the right pilot oil passage PR flows to the drain oil passage Pd through the priority control valve 51 and the lever electromagnetic control valve 27 and is returned to the tank 31.
- the switching valve 52 is controlled by the differential pressure between the left and right pilot oil passages PL and PR generated by the steering operation, thereby switching the priority control valve 51 to the steering wheel stage Sh. Therefore, the circuit configuration is simplified and the operation is stabilized.
- FIG. 8 shows a steering apparatus according to a third embodiment of the present invention.
- This steering device is different from the first and second embodiments only in the steering wheel priority valve 60, and the other configuration is the same as the other embodiments.
- the handle priority valve 60 different from the first embodiment will be described.
- the steering wheel priority valve 60 includes a priority control valve 61 provided in the middle of the left and right pilot oil passages PL and PR, and a switching valve 62 that switches the priority control valve 61.
- ⁇ Priority control valve 61> The left and right output ports of the orbit roll 26 are connected to the input port of the priority control valve 61 via the left and right pilot oil passages PL and PR. Further, the left and right output ports of the lever electromagnetic control valve 27 are connected to the other input ports of the priority control valve 61. The input port of the priority control valve 61 and the left and right output ports of the lever electromagnetic control valve 27 are connected by the left lever pilot oil passage PLl and the right lever pilot oil passage PRl.
- the priority control valve 61 is switched between the handle stage Sh and the lever stage Sl by the pilot hydraulic pressure from the switching valve 62. Specifically, when the pilot hydraulic pressure is not supplied, the operation is switched to the handle stage Sh, and when the pilot hydraulic pressure is supplied from the switching valve 52, the operation is switched to the lever stage Sl.
- the orbit roll 26 and the steering valve 25 are communicated with each other and the lever electromagnetic control valve 27 and the steering valve 25 are blocked.
- the orbit roll 26 and the steering valve 25 are disconnected from each other, and the lever electromagnetic control valve 27 and the steering valve 25 are communicated with each other.
- the switching valve 62 is a valve for switching the priority control valve 61 between the handle stage Sh and the lever stage Sl.
- the left and right pilot oil passages PL and PR are connected to the pilot port of the switching valve 62 via the shuttle valve 63.
- the left and right lever pilot oil passages PLl and PRl are connected to the input port of the switching valve 62 via the shuttle valve 64.
- the output port of the switching valve 62 is connected to the pilot port of the priority control valve 61.
- the switching valve 62 is switched to the cutoff stage Sb. Further, when the hydraulic oil is not flowing in the left and right pilot oil passages PL and PR, the switching valve 62 is switched to the communication stage St.
- FIG. 9 shows the flow of the steering hydraulic oil (solid line) and the pilot hydraulic oil (broken line) when the steering wheel is operated for turning to the left.
- the hydraulic oil input from the first input oil passage P01 is output from the orbit roll 26 to the left pilot oil passage PL.
- This hydraulic oil is input to the left pilot port of the direction control valve 25a of the steering valve 25 via the stop valve 35.
- the direction control valve 25a is switched to the left turn stage L by this pilot hydraulic pressure.
- the hydraulic oil flows through the left lever pilot oil passage PL1, and this hydraulic oil is input to the switching valve 62 via the shuttle valve 64. Since the switching valve 62 is switched to the communication stage St, the input hydraulic oil is input to the pilot port of the priority control valve 61. For this reason, the priority control valve 61 is switched to the lever stage S1.
- the hydraulic oil input from the second input oil path P02 is output from the joystick 22 to the left lever pilot oil path PLl.
- This hydraulic oil is supplied to the left pilot oil passage PL via the priority control valve 61, and is input to the left pilot port of the direction control valve 25a of the steering valve 25 as in the case of the steering operation described above. Therefore, the direction control valve 25a is switched to the left turn stage L. Further, the hydraulic oil in the right pilot oil passage PR is returned from the tank port T of the lever electromagnetic control valve 27 to the tank 31 through the drain oil passage Pd.
- the switching valve 52 is switched to the cutoff stage Sb. Therefore, the hydraulic oil from the lever electromagnetic control valve 27 is shut off by the switching valve 62, and the pilot hydraulic pressure is not supplied to the priority control valve 61. For this reason, the priority control valve 61 is switched to the handle stage Sh as in the case of the handle operation.
- This third embodiment also has the same operational effects as the second embodiment.
- FIG. 11 shows a steering apparatus according to a fourth embodiment of the present invention.
- This steering device differs from the first to third embodiments only in the steering wheel priority valve 70, and the other configuration is the same as the other embodiments.
- the handle priority valve 70 different from the first embodiment will be described.
- the handle priority valve 70 includes a priority valve main body 71, a throttle 72, and a check valve 73.
- the priority valve main body 71 is provided in the middle of the left and right lever pilot circuits PLl and PRl on the output side of the lever electromagnetic control valve 27. More specifically, a left lever pilot oil passage PLl and a right lever pilot oil passage PRl are connected to the output port of the lever electromagnetic control valve 27. The left lever pilot oil passage PLl is connected to the left pilot oil passage PL, and the right lever pilot oil passage PRl is connected to the right pilot oil passage PR.
- the priority valve body 71 is provided in the middle of the left and right lever pilot oil passages PL1, PR1.
- the priority valve main body 71 is controlled by the pilot hydraulic pressure, and is switched between the communication stage St and the cutoff stage Sb.
- the output port of the lever electromagnetic control valve 27 is connected to the left and right pilot oil passages PL, PR via the left and right lever pilot oil passages PL1, PR1. Further, at the shut-off stage Sb, the output port of the lever electromagnetic control valve 27 and the left and right pilot oil passages PL and PR are shut off.
- the throttle 72 is provided in the drain oil passage Pd.
- the drain oil passage Pd is an oil passage that connects between the drain T port of each valve and the tank 31.
- the throttle 72 is provided between the drain T port of the orbit roll 26 and the drain T port of the lever electromagnetic control valve 27 in the drain oil passage Pd.
- the oil passages before and after the throttle 72 are connected to the pilot port of the priority valve main body 71, respectively.
- the priority valve main body 71 is switched to the cutoff stage Sb.
- the check valve 73 is provided in parallel with the throttle 72. Then, when the differential pressure before and after the throttle 72 becomes equal to or higher than a predetermined pressure, it opens, and the upstream hydraulic oil is guided to the tank 31.
- FIG. 12 shows the flow of steering hydraulic oil (solid line) and pilot hydraulic oil (broken line) when the steering wheel is operated for turning to the left.
- the hydraulic oil is returned to the tank 31 from the T port of the orbit roll 26 as described above.
- This hydraulic oil passes through the throttle 72.
- the pressure on the upstream side (orbit roll 26 side) of the throttle 72 is higher than the pressure on the downstream side (lever electromagnetic control valve 27 side). Therefore, the priority valve main body 71 is switched to the cutoff stage Sb.
- the hydraulic oil input from the second input oil path P02 is output from the joystick 22 to the left lever pilot oil path PLl.
- This hydraulic oil is supplied to the left pilot oil passage PL via the priority valve main body 71, and is input to the left pilot port of the direction control valve 25a of the steering valve 25 as in the case of the steering operation described above. Therefore, the direction control valve 25a is switched to the left turn stage L.
- the pilot oil in the right pilot oil passage PR is returned from the drain T port of the lever electromagnetic control valve 27 to the tank 31 through the drain oil passage Pd.
- a mechanism for giving priority to steering wheel operation can be realized with a simple configuration, and the steering operation priority is ensured by stable operation. Can be executed.
Abstract
Description
[ホイールローダの全体構成]
本発明の第1実施形態によるステアリング装置が搭載されたホイールローダ1の全体構成を図1に示している。なお、図1はホイールローダ1の側面図である。
図2にステアリング装置20の構成を示している。このステアリング装置20は、フロントフレーム11をリアフレーム12に対して回動させて車両を旋回させるための装置である。
ステアリング弁25は、オービットロール26又はレバー用電磁制御弁27からのパイロット油圧に応じて、左右のステアリングシリンダ23L,23Rのいずれかにポンプ30からの作動油を供給するものである。
オービットロール26は、入力側のPポートが、第1入力油路P01を介してファンポンプ等のパイロット油圧用のポンプ(図示せず)に接続されている。このオービットロール26は、ハンドル21を左回転した場合はLポートから、またハンドル21を右回転させた場合はRポートから、ハンドル回転量に比例した作動油を吐出するものである。出力側のLポートには左パイロット油路PLが接続され、Rポートには右パイロット油路PRが接続されている。
レバー用電磁制御弁27は、入力側のPポートが、第2入力油路P02を介して、第1入力油路P01が接続されたポンプに接続されている。レバー用電磁制御弁27は、ジョイスティック22の操作に応じて、Pポートから入力された作動油を出力側のLポート又はRポートに吐出するものである。Lポートには左レバー用パイロット油路PLlが接続され、左レバー用パイロット油路PLlは左パイロット油路PLに接続されている。また、Rポートには右レバー用パイロット油路PRlが接続され、右レバー用パイロット油路PRlは右パイロット油路PRに接続されている。そして、左レバー用パイロット油路PLl及び右レバー用パイロット油路PRlにハンドル優先弁28が設けられている。
ハンドル優先弁28は、優先弁本体40と、第1絞り41と、チェック弁42と、第2絞り43と、を有している。
ここでは、左旋回時のステアリング装置の動作について説明する。なお、右旋回の場合の動作は、パイロット用及びステアリング用の作動油の流れる油路が異なるだけで、基本的な動作は同じである。
図3は、左旋回のためにハンドル操作を行った場合のステアリング用作動油(実線)とパイロット用作動油(破線)の流れを示している。
ここでは、ハンドル21が操作されておらず、ジョイスティック22のみが操作された場合について、図4を用いて説明する。図4では、ステアリング用作動油の流れを実線で示し、パイロット用作動油の流れを破線で示している。
ハンドル21を操作している際に、オペレータが誤ってジョイスティック22に触れ、ジョイスティック22が操作される場合がある。この場合は、ハンドル操作が優先される。
優先弁本体40が故障した場合、ハンドル21が操作されていても優先弁本体40が遮断ステージSbに切り替えられない可能性がある。
ホイールローダ1が左旋回のため最大限に回動したとき、ストップ弁35を、チェック弁を有するステージに機械的に移行させる。このため、オービットロール26からの作動油が方向制御弁25aに供給されない。一方、右パイロット油路PR内の作動油はタンク31へ戻るので、左右のパイロット油路PL,PRは共に「0」になる。このため、ホイールローダ1は最大限に左へ操舵されたまま維持される。右旋回の場合は、以上の逆の動作となる。
(1)ハンドル21が操作された場合はハンドル操作が優先される。したがって、ハンドル操作中にオペレータが誤ってジョイスティック22に触れた場合でも、意図しないステアリング操作がなされるのを防止できる。
図5に本発明の第2実施形態によるステアリング装置を示す。このステアリング装置は、ハンドル優先弁50のみが第1実施形態と異なり、他の構成は第1実施形態と同じである。以下、第1実施形態と異なるハンドル優先弁50について説明する。
ハンドル優先弁50は、左右のパイロット油路PL,PRの途中に設けられた優先制御弁51と、この優先制御弁51を切り替える切替弁52と、を有している。
優先制御弁51の入力ポートには、左右のパイロット油路PL,PRを介してオービットロール26の左右の出力ポートが接続されている。また、優先制御弁51の他の入力ポートには、レバー用電磁制御弁27の左右の出力ポートが接続されている。優先制御弁51の入力ポートとレバー用電磁制御弁27の左右の出力ポートとは、左レバー用パイロット油路PLlと右レバー用パイロット油路PRlとによって接続されている。この優先制御弁51は、切替弁52からのパイロット油圧によって、ハンドル用ステージShとレバー用ステージSlとに切り替えられる。具体的には、パイロット油圧が供給されない場合はハンドル用ステージShに切り替えられ、切替弁52からパイロット油圧が供給されるとレバー用ステージSlに切り替えられる。
切替弁52は、優先制御弁51をハンドル用ステージShとレバー用ステージSlとの間で切り替えるための弁である。この切替弁52のパイロットポートには、左右のパイロット油路PL,PRの油圧が入力されている。切替弁52においては、左右のパイロット油路PL,PRの間に差圧が生じると遮断ステージSbに切り替えられ、両油路PL,PRの圧力が同じ場合は連通ステージStに切り替えられる。
ここでは、第1実施形態と同様に、左旋回時のステアリング装置の動作について説明する。
図6は、左旋回のためにハンドル操作を行った場合のステアリング用作動油(実線)とパイロット用作動油(破線)の流れを示している。
ジョイスティック22のみが操作された場合について、図7を用いて説明する。ハンドル21が操作されていない場合は、左右のパイロット油路PL,PRにおいてオービットロール26と優先制御弁51との間に作動油は流れない。したがって、両パイロット油路PL,PRの間に圧力差は生じない。このため、切替弁52は連通ステージStに切り替えられる。
ハンドル21を操作している際に、オペレータが誤ってジョイスティック22に触れ、ジョイスティック22が操作される場合がある。この場合は、ハンドル操作が優先される。
(1)ハンドル21が操作された場合はハンドル操作が優先される。したがって、ハンドル操作中にオペレータが誤ってジョイスティック22に触れた場合でも、意図しないステアリング操作がなされるのを防止できる。
図8に本発明の第3実施形態によるステアリング装置を示す。このステアリング装置は、ハンドル優先弁60のみが第1及び第2実施形態と異なり、他の構成は他の実施形態と同じである。以下、第1実施形態と異なるハンドル優先弁60について説明する。
ハンドル優先弁60は、左右のパイロット油路PL,PRの途中に設けられた優先制御弁61と、この優先制御弁61を切り替える切替弁62と、を有している。
優先制御弁61の入力ポートには、左右のパイロット油路PL,PRを介してオービットロール26の左右の出力ポートが接続されている。また、優先制御弁61の他の入力ポートには、レバー用電磁制御弁27の左右の出力ポートが接続されている。優先制御弁61の入力ポートとレバー用電磁制御弁27の左右の出力ポートとは、左レバー用パイロット油路PLlと右レバー用パイロット油路PRlとによって接続されている。この優先制御弁61は、切替弁62からのパイロット油圧によって、ハンドル用ステージShとレバー用ステージSlとに切り替えられる。具体的には、パイロット油圧が供給されない場合はハンドル用ステージShに切り替えられ、切替弁52からパイロット油圧が供給されるとレバー用ステージSlに切り替えられる。
切替弁62は、優先制御弁61をハンドル用ステージShとレバー用ステージSlとの間で切り替えるための弁である。左右のパイロット油路PL,PRは、シャトル弁63を介して切替弁62のパイロットポートに接続されている。また、左右のレバー用パイロット油路PLl,PRlは、シャトル弁64を介して切替弁62の入力ポートに接続されている。また、切替弁62の出力ポートは優先制御弁61のパイロットポートに接続されている。
ここでは、第1実施形態と同様に、左旋回時のステアリング装置の動作について説明する。
図9は、左旋回のためにハンドル操作を行った場合のステアリング用作動油(実線)とパイロット用作動油(破線)の流れを示している。
ジョイスティック22のみが操作された場合について、図10を用いて説明する。ハンドル21が操作されていない場合は、左右のパイロット油路PL,PRにおいてオービットロール26と優先制御弁61との間に作動油は流れない。したがって、切替弁62のパイロットポートにはパイロット油圧は供給されない。このため、切替弁52は連通ステージStに切り替えられる。
ハンドル21を操作している際に、オペレータが誤ってジョイスティック22に触れ、ジョイスティック22が操作される場合がある。この場合は、ハンドル操作が優先される。
この第3実施形態においても、第2実施形態と同様の作用効果を有する。
図11に本発明の第4実施形態によるステアリング装置を示す。このステアリング装置は、ハンドル優先弁70のみが第1~第3実施形態と異なり、他の構成は他の実施形態と同じである。以下、第1実施形態と異なるハンドル優先弁70について説明する。
ハンドル優先弁70は、優先弁本体71と、絞り72と、チェック弁73と、を有している。
優先弁本体71は、レバー用電磁制御弁27の出力側で左右のレバー用パイロット回路PLl,PRlの途中に設けられている。より詳細には、レバー用電磁制御弁27の出力ポートには左レバー用パイロット油路PLl及び右レバー用パイロット油路PRlが接続されている。左レバー用パイロット油路PLlは左パイロット油路PLに接続され、右レバー用パイロット油路PRlは右パイロット油路PRに接続されている。そして、優先弁本体71は、左右のレバー用パイロット油路PLl、PRlの途中に設けられている。
絞り72はドレン油路Pdに設けられている。ドレン油路Pdは、前述のように、各弁のドレン用のTポートとタンク31との間を接続する油路である。絞り72は、このドレン油路Pdにおいて、オービットロール26のドレン用のTポートとレバー用電磁制御弁27のドレン用のTポートとの間に設けられている。
チェック弁73は絞り72に並列に設けられている。そして、絞り72の前後の差圧が所定の圧力以上になった場合に開いて、上流側の作動油をタンク31に導く。
ここでは、第1実施形態と同様に、左旋回時のステアリング装置の動作について説明する。
図12は、左旋回のためにハンドル操作を行った場合のステアリング用作動油(実線)とパイロット用作動油(破線)の流れを示している。
ジョイスティック22のみが操作された場合について、図13を用いて説明する。ハンドル21が操作されていない場合は、オービットロール26には作動油は流れない。このため、優先弁本体71にはパイロット油圧は供給されていない。したがって、優先弁本体71は連通ステージStに切り替えられている。
ハンドル21を操作している際に、作業者が誤ってジョイスティック22に触れ、ジョイスティック22が操作される場合がある。この場合は、ハンドル操作が優先される。
この第4実施形態においても、前記同様に、ハンドル21が操作された場合はハンドル操作が優先され、意図しないステアリング操作がなされるのを防止できる。また、回路構成が簡単になり、作動が安定する。
本発明は以上のような実施形態に限定されるものではなく、本発明の範囲を逸脱することなく種々の変形又は修正が可能である。
20 ステアリング装置
21 ハンドル
22 ジョイスティック
23L,23R ステアリングシリンダ
25 ステアリング弁
26 オービットロール(ハンドル用制御弁)
27 レバー用電磁制御弁
28,50,60,70 ハンドル優先弁
30 ポンプ
31 タンク
40,71 優先弁本体
41,72 第1絞り
42,73 チェック弁
43 第2絞り
51,61 優先制御弁
52,62 切替弁
PL,PR パイロット油路
PLl,PRl レバー用パイロット油路
Pd ドレン油路
Claims (9)
- フロントフレームとリアフレームとが水平方向に回動自在に連結されたホイールローダのステアリング装置であって、
操舵のために回転操作されるハンドルと、
操舵のために傾動操作されるレバーと、
伸縮することによって前記フロントフレームを前記リアフレームに対して回動するためのステアリングシリンダと、
パイロット油圧によって前記ステアリングシリンダに対する作動油の供給方向を制御するステアリング弁と、
前記ステアリング弁を介して前記ステアリングシリンダに作動油を供給するためのポンプと、
前記ハンドルの回転操作により前記ステアリング弁に供給方向制御用のパイロット油圧を供給するハンドル用制御弁と、
前記レバーの傾動操作により前記ステアリング弁に供給方向制御用のパイロット油圧を供給するレバー用電磁制御弁と、
前記ハンドルが操作された際に作動油が前記ハンドル用制御弁を流れることにより発生する油圧回路の差圧又は絶対圧によって前記レバー用電磁制御弁から前記ステアリング弁に供給されるパイロット油圧を遮断するハンドル優先弁と、
を備えたホイールローダのステアリング装置。 - 前記ハンドル優先弁は、
前記ハンドル用制御弁に作動油を供給する回路の途中に設けられた第1絞りと、
前記レバー用電磁制御弁からのパイロット油圧を前記ステアリング弁に供給する連通ステージと、前記パイロット油圧が前記ステアリング弁に供給されるのを遮断する遮断ステージとを有し、前記第1絞りの前後に差圧が発生した場合に前記遮断ステージに切り替えられる優先弁本体と、
を有する、請求項1に記載のホイールローダのステアリング装置。 - 前記ハンドル優先弁は、前記レバー用電磁制御弁に作動油を供給する回路の途中に設けられ、前記第1絞りより絞り径の小さい第2絞りをさらに有している、請求項2に記載のホイールローダのステアリング装置。
- 前記第1絞りと並列に、前記第1絞りの前後の差圧が所定圧以上になったときに開いて作動油を前記ハンドル用制御弁に供給するとともに、前記ハンドル用制御弁から逆に流れる作動油を停止するチェック弁をさらに備えた、請求項2又は3に記載のホイールローダのステアリング装置。
- 前記ハンドル用制御弁と前記ステアリング弁との間に設けられた左パイロット油路及び右パイロット油路をさらに備え、
前記ハンドル優先弁は、
前記ハンドル用制御弁及び前記レバー用電磁制御弁と前記ステアリング弁との間に配置され、前記ハンドル用制御弁と前記ステアリング弁とを連通するとともに前記レバー用電磁制御弁と前記ステアリング弁との間を遮断するハンドル用ステージと、前記ハンドル用制御弁と前記ステアリング弁との間を遮断するとともに前記レバー用電磁制御弁と前記ステアリング弁とを連通するレバー用ステージと、を有する優先制御弁と、
前記左右のパイロット油路の間に差圧が発生したときに前記優先制御弁を前記ハンドル用ステージに切り替える切替弁と、
を有する、請求項1に記載のホイールローダのステアリング装置。 - 前記レバー用電磁制御弁と前記優先制御弁との間に設けられた左レバー用パイロット油路及び右レバー用パイロット油路をさらに備え、
前記切替弁は、前記左パイロット油路と前記右パイロット油路との間に差圧がなく、かつ前記左レバー用パイロット油路と前記右レバー用パイロット油路との間に差圧が発生したときに前記優先制御弁を前記レバー用ステージに切り替える、
請求項5に記載のホイールローダのステアリング装置。 - 前記ハンドル用制御弁と前記ステアリング弁との間に設けられた左パイロット油路及び右パイロット油路をさらに備え、
前記ハンドル優先弁は、
前記ハンドル用制御弁及び前記レバー用電磁制御弁と前記ステアリング弁との間に設けられ、前記ハンドル用制御弁と前記ステアリング弁とを連通するとともに前記レバー用電磁制御弁と前記ステアリング弁との間を遮断するハンドル用ステージと、前記ハンドル用制御弁と前記ステアリング弁との間を遮断するとともに前記レバー用電磁制御弁と前記ステアリング弁とを連通するレバー用ステージと、を有する優先制御弁と、
前記ハンドル用制御弁に作動油が流れたときに前記優先制御弁を前記ハンドル用ステージに切り替え、前記レバー用電磁制御弁にのみ作動油が流れたときに前記優先制御弁を前記レバー用ステージに切り替える切替弁と、
を有する、請求項1に記載のホイールローダのステアリング装置。 - 前記ハンドル用制御弁と前記ステアリング弁との間に設けられた左パイロット油路及び右パイロット油路と、
前記ステアリング弁からの戻り油を前記ハンドル用制御弁を介してタンクに導く戻り油路と、
をさらに備え、
前記レバー用電磁制御弁の出力ポートは前記左右のパイロット油路に接続されており、
前記ハンドル優先弁は、
前記戻り油路において前記ハンドル用制御弁と前記タンクとの間に設けられた絞りと、
前記レバー用電磁制御弁の出力ポートと前記左右のパイロット油路との間に設けられ、前記レバー用電磁制御弁の出力ポートと前記左右のパイロット油路とを連通する連通ステージと、前記レバー用電磁制御弁の出力ポートと前記左右のパイロット油路との間を遮断する遮断ステージと、を有し、前記絞りの前後の差圧が生じた場合は前記遮断ステージに切り替えられ、前記絞りの前後に差圧がない場合は前記連通ステージに切り替えられる、
請求項1に記載のホイールローダのステアリング装置。 - 前記絞りと並列に設けられ、前記絞りの前後の差圧が所定圧以上になったときに開いて作動油を前記タンクに戻すチェック弁をさらに備えた、請求項8に記載のホイールローダのステアリング装置。
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JP2012523534A JP5362113B1 (ja) | 2012-03-29 | 2012-04-19 | ホイールローダのステアリング装置 |
EP12873379.7A EP2774827B1 (en) | 2012-03-29 | 2012-04-19 | Steering device of wheel loader |
CN201280034261.4A CN103648890B (zh) | 2012-03-29 | 2012-04-19 | 轮式装载机的转向装置 |
US14/122,405 US9085319B2 (en) | 2012-03-29 | 2012-04-19 | Steering device for wheel loader |
US14/726,670 US9309647B2 (en) | 2012-03-29 | 2015-06-01 | Steering device for wheel loader |
US14/726,658 US9309646B2 (en) | 2012-03-29 | 2015-06-01 | Steering device for wheel loader |
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US14/726,670 Division US9309647B2 (en) | 2012-03-29 | 2015-06-01 | Steering device for wheel loader |
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