JP4105454B2 - Steering device for front and rear wheel steering vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering device for a front and rear wheel steering vehicle in which front wheels and rear wheels are steered by hydraulic pressure applied to a power cylinder.
[0002]
[Prior art]
Conventionally, in a large vehicle such as a truck, a vehicle capable of steering both front wheels and rear wheels is known. Among them, a switch that is capable of alternately switching between the normal travel mode and the crab travel mode by a switch provided near the driver's seat is known. Here, the crab traveling refers to traveling with the front wheels and the rear wheels oriented in the same direction, whereby the vehicle moves in parallel.
[0003]
The supply of oil to the power cylinder provided on the front axle for changing the direction of the front wheels is generally adjusted by a control valve that changes the position of the valve in conjunction with the rotation of the steering wheel. ing.
[0004]
[Problems to be solved by the invention]
However, in the conventional steering device for front and rear wheel steering vehicles, when the steering wheel is rotated at a high speed, the amount of oil supplied to the power cylinder is insufficient and the steering force of the front wheels becomes extremely large. was there.
[0005]
The present invention solves such a conventional problem. Even when the steering wheel is rotated at a high speed, the amount of oil supplied to the power cylinder is not short, and the front wheel can sufficiently secure the steering force. An object of the present invention is to provide a steering device for a wheel steering vehicle.
[0006]
[Means for Solving the Problems]
A steering device for a front and rear wheel steering vehicle according to the present invention includes a front axle and a rear axle provided with a power cylinder, a link mechanism for transmitting the rotation of the steering wheel to a steering mechanism provided on the front axle, and a pressure feed from a pump. And a hydraulic circuit that supplies hydraulic oil to the front cylinder and the power cylinder of the rear axle, and the hydraulic circuit includes a front passage that supplies oil to the front axle, A rear flow path for refueling the rear axle, and a flow path switching device provided in the rear flow path, and a connection for connecting the front flow path and the flow path switching device A flow path, a check valve provided in each of the front flow path and the connection flow path, provided between the flow path switching device and a power cylinder of the rear axle, via the rear path. Characterized by comprising a pressure regulating device for adjusting the pressure of oil fed to the rear axle.
[0009]
(Function)
In the steering device for a front-rear wheel steering vehicle according to the present invention , a flow path switching device is provided in the rear flow path, and the flow path switching apparatus and the front flow path are connected by a connection flow path to supply oil to the rear axle. With this pump, it is possible to supply oil to the front axle . In addition, a check valve is provided in the connection channel, and oil in the front channel is prevented from flowing into the rear channel.
[0010]
In addition, a check valve is provided in the front flow path, and oil that flows from the rear flow path through the connection flow path into the front flow path is prevented from flowing in the direction in which the pump is located. Further, the pressure adjusting device is connected to the flow path in the middle of the oil passing through the flow path switching device and going to the rear axle.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a hydraulic circuit of one embodiment (corresponding to claims 1 to 4) of a steering device for a front and rear wheel steering vehicle of the present invention, and FIG. 3 shows front and rear wheels of the present invention. 1 shows a configuration of a steering system according to an embodiment of a steering device for a steered vehicle.
[0012]
In the steering system shown in FIG. 3, the front wheel side has a steering wheel 1 that is a steering force input means for changing the direction of the front wheel 2 </ b> A, a steering gear box 3, and a pitman arm connected to the steering gear box 3. 5.
As a link mechanism, one end side of the pitman arm 5 is connected to the other end side of the pitman link 7, and an idler arm 9A for transmitting a steering force to the front wheels 2A and 2B is provided on one end side of the pitman link 7. It has been. A drag link 11A is connected to one end of the idler arm 9A, and a steering force is transmitted to the front wheel 2A via the drag link 11A. The other end of the middle link 15 is connected to the other end of the idler arm 9A. The other end side of the idler arm 9B is connected to one end side of the middle link 15, and the other end side of the drag link 11B is connected to one end side of the idler arm 9B, and the steering force is transmitted via the drag link 11B. It is transmitted to the front wheel 2B.
[0013]
The first and second axle devices 13A and 13B, which are front axles, have the same steering mechanism 16. Specifically, the steering arms 17R and 17L rotated by the movement of the drag links 11A and 11B, the power cylinders 1CR, 1CL, 2CR and 2CL connected to the steering arms 17R and 17L, and the steering arm 17R, respectively. , 17L.
[0014]
In the steering system shown in FIG. 3, on the rear wheel side, the rear and third axles 13C and 13D are not connected to the steering wheel 1, and the power cylinders 3CR, 3CL, 4CR, Only the movement of the piston 23 press-fitted into the 4CL changes the direction of the rear wheels 4A and 4B. Further, the third axle device 13C and the fourth axle device 13D, which are rear axles, use the steering lever 25 and drag links 27 connected to both ends thereof to synchronize the directions of the rear wheels 4A and 4B. Has been.
[0015]
Further, the third and fourth axle devices 13C and 13D have the same steering mechanism 16 as the first and second axle devices 13A and 13B.
In changing the directions of the front wheels 2A and 2B, the steering wheel 1 is first rotated. Then, the steering arm 17R rotates in conjunction with it, and further, in conjunction with it, the steering arm 17L rotates through the tie rod 19, and the directions of the front wheels 2A and 2B are changed. At this time, the directions of the front wheels 2A and 2B are also changed by the oil pressure. That is, when the steering wheel 1 is rotated, the hydraulic pressure applied to the power cylinders 1CR, 1CL, 2CR, 2CL changes in conjunction with the rotation of the steering wheel 1, and the piston 23 moves in the axial direction of the power cylinders 1CR, 1CL, 2CR, 2CL. The arms 17R and 17L are rotated to change the direction of the front wheels 2A and 2B.
[0016]
In changing the direction of the rear wheels 4A and 4B, when a button near the driver's seat (not shown) is pressed, the duty ratio of the electromagnetic valve 41 changes, the amount of oil 28 passing through the electromagnetic valve 41 changes, and the piston 23 Moves in the axial direction of the power cylinders 3CR, 3CL, 4CR, 4CL, the steering arms 17R, 17L are rotated, and the directions of the rear wheels 4A, 4B are changed.
[0017]
FIG. 1 shows a state in which the front wheels 2A and 2B are controlled by the hydraulic circuit 44 of the steering device for the front and rear wheel steering vehicle in this embodiment.
The hydraulic circuit 44 includes an oil pump 29A having a discharge amount of 80 cc / rev that pumps oil 28 to the power cylinders 1CR, 1CL, 2CR, and 2CL, and a discharge amount 40cc that pumps oil 28 to the power cylinders 3CR, 3CL, 4CR, and 4CL. / Rev oil pump 29B. A reservoir 46 filled with oil 28 is provided as a supply source of oil 28.
[0018]
The hydraulic circuit 44 adjusts the flow rate and pressure when supplying the oil 28 pumped from the oil pumps 29A, 29B to the power cylinders 1CR, 1CL, 2CR, 2CL, 3CR, 3CL, 4CR, 4CL. For this purpose, flow rate pressure adjusting valves 31A and 31B are provided. The flow rate pressure adjusting valves 31A and 31B are constituted by relief valves 33A and 33B which are pressure adjusting devices, and orifices 35A and 35B for adjusting the flow rate. Here, the oil pump 29B has a smaller discharge amount than the oil pump 29A, but the maximum operating pressure of the relief valve 33B is larger than that of the relief valve 33A.
[0019]
Further, the hydraulic circuit 44 includes a control valve 39 that is operated by turning the steering wheel 1, an electromagnetic valve 41 that is electrically controlled, and a rear side for supplying oil to the power cylinders 3CR, 3CL, 4CR, and 4CL. It has an electromagnetic valve 47 which is a flow path switching device connected to the flow path 45. The hydraulic circuit 44 has a connecting channel 51 that connects the front channel 49 and an electromagnetic valve 47 that is a channel switching device. The connecting channel 51 is provided with a check valve 53. ing. Similarly, a check valve 55 is provided in the front flow path 49. Furthermore, the hydraulic circuit 44 has a relief valve 57 that is a pressure adjusting device that adjusts the hydraulic pressure of the oil 28 that passes through the electromagnetic valve 47 and travels toward the power cylinders 3CR, 3CL, 4CR, and 4CL.
[0020]
In the hydraulic circuit 44 of the present embodiment configured as described above, the oil 28 is controlled as follows.
First, the flow of the oil 28 in the hydraulic circuit 44 when the first axle device 13A and the second axle device 13B are operated will be described.
Here, since both the oil pump 29A and the oil pump 29B are activated by the rotation of the engine 37, the flow of the oil 28 pumped by the oil pump 29A will be described first.
[0021]
First, the oil 28 sucked through the tube 43 by the oil pump 29A using the engine 37 as a power source is partly stored in the reservoir by the flow rate pressure adjustment valve 31A so that the flow rate and pressure become predetermined values. Return to 46. Next, the oil 28 having a predetermined flow rate and pressure flows into the control valve 39, and the outflow direction (direction of the front wheels 2A and 2B) is selected. Subsequently, it flows into the power cylinders 1CR, 1CL, 2CR, 2CL and moves the piston 23. Finally, due to the movement of the piston 23, the discharged oil 28 is discharged to the reservoir 46 via the control valve 39.
[0022]
Next, the flow of the oil 28 pumped by the oil pump 29B will be described.
The oil 28 sucked up through the tube 43 by the oil pump 29B using the engine 37 as a power source is part of the oil 28 in the reservoir 46 so that the flow rate and pressure become predetermined values by the flow rate pressure adjustment valve 31B. Returned. Next, the oil 28 whose flow rate and pressure are set to predetermined values is discharged to the connection flow path 51 via the electromagnetic valve 47. Next, the oil 28 is connected to the front flow path 49 via the check valve 53. Subsequently, it flows into the power cylinders 1CR, 1CL, 2CR, 2CL via the control valve 39, and the piston 23 is moved. Finally, due to the movement of the piston 23, the discharged oil 28 is discharged to the reservoir 46 via the control valve 39.
[0023]
Next, the flow of the oil 28 in the hydraulic circuit 44 when the third and fourth axle devices 13C and 13D are operated will be described with reference to FIG.
The oil 28 sucked up through the tube 43 by the oil pump 29B is returned to the reservoir 46 by the flow rate pressure adjustment valve 31B so that the flow rate and pressure become predetermined values. Next, the oil 28 whose flow rate and pressure are set to predetermined values is directed to the electromagnetic valve 41 via the electromagnetic valve 47. Next, a part of the oil 28 is returned again to the reservoir 46 by the relief valve 57 so that the pressure becomes a predetermined value. Subsequently, the oil 28 whose pressure is set to a predetermined value flows into the electromagnetic valve 41, and the outflow direction (direction of the rear wheels 4A and 4B) is selected. Subsequently, it flows into the power cylinders 3CR, 3CL, 4CR, 4CL and moves the piston 23. Finally, due to the movement of the piston 23, the discharged oil 28 is discharged to the reservoir 46 via the electromagnetic valve 41.
[0024]
In the steering device for a front and rear wheel steering vehicle according to the above-described embodiment, the electromagnetic valve 47 is provided in the rear flow path 45, and the electromagnetic valve 47 and the front flow path 49 are connected by the connection flow path 51. When the third and fourth axle devices 13C and 13D are not used, the oil 28 pumped by the oil pump 29B is supplied to the first and second axles. Since it can be sent to the devices 13A and 13B, even if the steering wheel 1 is rotated at a high speed, the amount of oil supplied to the power cylinders 1CR, 1CL, 2CR and 2CL is not insufficient, and the steering force of the front wheels 2A and 2B is increased. It can be secured sufficiently.
[0025]
Even if the oil pump 29A breaks down, the oil 28 can be pumped to the first and second axle devices 13A and 13B by the oil pump 29B, preventing the vehicle from getting stuck on the work site or on the road. be able to.
In addition, a check valve 53 is provided in the connection flow path 51 to prevent the oil 28 in the front flow path 49 from flowing into the rear flow path 45, so that the rear flow path 45, the electromagnetic valve from the oil pump 29B is prevented. Even if the pressure of the oil 28 pumped to the connection channel 51 via 47 is low, the first and second axle devices 13A and 13B can be controlled by the oil 28 pumped from the oil pump 29A.
[0026]
Further, a check valve 55 is provided in the front flow path 49, and the oil 28 that has flowed into the front flow path 49 from the rear flow path 45 through the electromagnetic valve 47 and the connection flow path 51 is directed in the direction in which the oil pump 29A is present. Since it is prevented from flowing, even if the pressure of the oil 28 pumped from the oil pump 29A to the first and second axle devices 13A and 13B via the flow pressure control valve 31A is low, the oil pump 29B pumps the oil. The oil 28 can control the first and second axle devices 13A and 13B.
[0027]
Further, the pressure of the oil 28 that passes through the electromagnetic valve 47 and travels toward the third and fourth axle devices 13C and 13D is adjusted by the relief valve 57, and a predetermined hydraulic pressure is obtained, so that the maximum pressure of the relief valve 33B is increased. In addition, the hydraulic pressure applied to the power cylinders 1CR, 1CL, 2CR, 2CL when the electromagnetic valve 47 is circulated with the connecting flow path 51 can be increased.
[0028]
【The invention's effect】
According to the present invention, the flow path switching device is provided in the rear flow path, and the flow path switching apparatus and the front flow path are connected by the connection flow path, so that fueling to the front axle is possible. When the side axle is not used, the oil pumped by the pump can be sent to the front axle, so even if the steering wheel is rotated at high speed, the amount of oil supplied to the power cylinder is not insufficient, and the front wheels are steered. Enough power can be secured.
[0029]
Further, even if the front axle pump breaks down, oil can be pumped to the front axle with the rear axle pump, and the vehicle can be prevented from getting stuck on the work site or on the road. In addition, a check valve is provided in the connecting flow path to prevent the oil in the front flow path from flowing into the rear flow path, so the rear flow path and flow path switching device can be removed from the rear axle pump. Even if the pressure of the oil pumped to the connecting flow path is low, the front axle can be controlled by the oil pumped from the oil pump for the front axle.
[0030]
Also, a check valve is provided in the front flow path, and oil that has entered the front flow path from the rear flow path through the flow switching device and the connection flow path may flow in the direction in which the front axle pump is located. Therefore, even if the pressure of the oil pumped from the front axle pump is low, the front axle can be controlled by the oil pumped from the rear axle pump.
[0031]
Further, since the pressure adjusting device is connected to the flow path in the middle of the oil passing through the flow path switching device and going to the rear axle, if the oil pressure is higher than the set value of the pressure adjusting device, a predetermined oil pressure is set. The pressure can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a hydraulic circuit during front axle control in a steering device for a front and rear wheel steering vehicle according to an embodiment.
FIG. 2 is an explanatory diagram showing a hydraulic circuit during rear axle control in the steering device for a front and rear wheel steering vehicle of the present embodiment.
FIG. 3 is an explanatory diagram showing a steering system in the steering device for the front and rear wheel steering vehicle of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering wheel 13A 1st axle apparatus 13B 2nd axle apparatus 13C 3rd axle apparatus 13D 4th axle apparatus 16 Steering mechanism 26,44 Hydraulic circuit 28 Oil 29A, 29B Pump 45 Rear flow path 47 Flow path switching apparatus 49 Front flow Passage 51 connection passage 53, 55 check valve 57 pressure regulator 1CR, 1CL, 2CR, 2CL, 3CR, 3CL, 4CR, 4CL power cylinder

Claims (1)

A front axle and a rear axle provided with a power cylinder;
A link mechanism for transmitting the rotation of the steering wheel to a steering mechanism provided on the front axle;
A hydraulic circuit for supplying oil pumped from the pump to the power cylinders of the front axle and the rear axle;
In a steering device for a front and rear wheel steering vehicle having
The hydraulic circuit includes a front flow path that supplies oil to the front axle, and a rear flow path that supplies oil to the rear axle,
A channel switching device provided in the rear channel;
A connecting flow path for connecting the front flow path and the flow path switching device;
A check valve provided in each of the front channel and the connection channel;
A pressure adjusting device that is provided between the flow path switching device and the power cylinder of the rear axle, and that adjusts the pressure of oil sent to the rear axle through the rear passage;
Steering system of the front and rear wheel steering vehicle, characterized in that it comprises a.

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