JP3687257B2 - Steering device for mobile agricultural machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering apparatus for a mobile agricultural machine that can quickly change the direction of a machine during turning.
[0002]
[Prior art]
For example, in the case of a mobile agricultural machine such as a tractor, the steering angle of the steered wheels is set to the maximum when the steering handle is rotated about two turns to the right or left from the neutral position. The tractor often turns the body suddenly at the end of the field, but it is not easy to change the direction by turning the steering handle twice at a time. In view of this, a proposal has been made that the vehicle can be turned sharply even with a small operation amount of the steering wheel (Japanese Patent Laid-Open No. 8-26126).
[0003]
[Problems to be solved by the invention]
In the steering device (turning device) described in the above publication, the flow of pressure oil from the pressure oil supply source (hydraulic supply means) to the steering hydraulic actuator (power steering cylinder) according to the operation direction of the steering handle (steering wheel). And a power steering unit that adjusts the flow rate of the pressure oil that passes according to the operation amount of the steering handle, and according to the steering state of the steering handle, the supply of the pressure oil to the steering hydraulic actuator, The flow is switched between the flow supplied via the power steering unit and the flow supplied directly.
[0004]
In other words, pressure oil is normally supplied from the hydraulic supply source to the steering hydraulic actuator via the power steering unit, but when the steering handle is operated under a predetermined condition, the pressure is directly applied from the hydraulic supply source to the steering hydraulic actuator. Oil will be supplied. Therefore, when turning under the predetermined condition, the steering wheel operation is not involved in steering the steered wheel, and at this time, even if there is an obstacle in the course of the aircraft, there is a problem that this cannot be avoided. It was.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows. That is, the steering system of the mobile agricultural machine according to the present invention, power for controlling the flow of pressure oil to the steering hydraulic actuator (16) from the steering wheel (9) the hydraulic fluid supply source in response to the operation direction of (10) In the steering device for a mobile agricultural machine provided with a steering unit (12) , a vehicle speed sensor (27) for detecting a vehicle speed of the mobile agricultural machine and a sensor (28) for detecting an operation speed of the steering handle (9) are provided, An opening / closing means (25) is provided between the oil passage between the power steering unit (12) and the steering hydraulic actuator (16) for switching between a state in which the entire amount of oil in the oil passage is allowed to pass and a portion in which the oil is allowed to pass. In the turning operation of the airframe in which the vehicle speed is not more than the set speed and the handle speed is not less than the set speed is detected by the sensors (27, 28), the opening means (25) Is characterized in that a control means (29) to increase the steering speed of the steering wheel (2, 2) the amount of oil between the oil passage as a state for communicating all.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
First, an outline of a tractor provided with the steering device of the present invention will be described. A tractor 1 shown in FIG. 1 is a front and rear four-wheel drive vehicle, and includes front wheels 2 and 2 and rear wheels 3 and 3 at four corners of the fuselage. The rotational power of the engine 5 mounted on the front of the machine body is appropriately shifted by a transmission in the transmission case 6 provided at the rear of the engine, and the power is transmitted to the front wheels 2, 2 and the rear wheels 3, 3. . By a 4WD switching device (not shown), a rear wheel 2WD state in which only the rear wheel is driven, a 4WD state in which the front wheel and the rear wheel are driven at a constant speed, and a front wheel acceleration in which the front wheel is driven at a higher speed than the rear wheel. It can be switched to the state. Fenders 7 and 7 are attached from the front to the top of the left and right rear wheels 3 and 3, and a seat 8 is provided between the left and right fenders. A steering handle 9 is provided in front of the seat 8 to steer the front wheels 2 and 2 as steering wheels.
[0007]
FIG. 2 shows a hydraulic circuit of the first example of the steering device. In this steering apparatus, a part of the pressure oil delivered from the hydraulic pump 10 which is a pressure oil supply source is supplied to a power steering unit (hereinafter referred to as “power steering unit”) 12 through an oil passage 11. The power steering unit 12 includes a directional control valve 12a and a pump 12b that are respectively operated by a steering shaft 9a connected to the steering handle 9. When the steering handle 9 is in the neutral position, the oil passage 11 and the oil passage 13 are provided. And the pressure oil is returned to the oil tank 14 as it is, and when the steering handle 9 is turned to the right from the neutral position, the oil passage 11 and the oil passage 15 are connected, and the pressure oil having a flow rate corresponding to the turning amount of the steering handle is used for steering. While being sent to the right cylinder chamber 16a of the power steering cylinder 16 which is a hydraulic actuator, the oil passage 17 and the oil passage 13 are connected, the oil in the left cylinder chamber 16b of the cylinder is returned to the oil tank 14, and the steering handle 9 is neutralized. When it is turned to the left from the position, the oil passage 11 and the oil passage 17 are connected, and the pressure oil at a flow rate corresponding to the turning amount of the steering handle is supplied to the power steering cylinder 16. Together and sent to the left cylinder chamber 16b, is configured as the oil of the oil passage 15 and the oil passage 13 and ties the right cylinder chamber 16b of the cylinder is returned to the oil tank 14. A part of the oil returned to the oil tank 14 is supplied to the main clutch 18 as lubricating oil. Reference numerals 20, 21, and 22 denote relief valves, respectively.
[0008]
Further, a return oil passage 24 that connects the oil passages 15, 17 and the oil passage 13 is provided. The return oil passage 24 is connected to the oil passages 15 and 17 by a power steering flow rate adjusting valve 25 as an opening / closing means for opening and closing the circuit. In a state where the return circuit 24 is open, a part (about ½) of the pressure oil that has passed through the power steering unit 12 is returned to the oil tank 14 through the return oil passage 24, and the rest is supplied to the power steering cylinder 16. . When the power steering flow rate adjustment valve 25 is driven and the return circuit 24 is closed, the entire amount of pressure oil that has passed through the power steering unit 12 is supplied to the power steering cylinder 16.
[0009]
The power steering flow rate adjusting valve 25 is a solenoid valve, and as shown in FIG. 3, an engine speed sensor 26 for detecting the engine speed, a vehicle speed sensor 27 for detecting the vehicle speed, and a steering sensor 28 for operating the steering handle 9. Based on this detection result, a drive output is output from the microcomputer 29 to the solenoid 25a of the power steering flow rate adjusting valve 25. FIG. 4 is a flowchart of the control, where the vehicle speed is a set speed (for example, 6 km / h) or less, the engine speed is the set speed (for example, 1500 rpm) or more, and the steering wheel operation speed is a set speed (for example, 60 rpm) or more. The return oil passage 24 is closed by outputting to the solenoid 25a, and if at least one of the above conditions is not satisfied, the return oil passage 24 is kept open without outputting to the solenoid 25a.
[0010]
Pilot check valves 31 and 31 are respectively provided between the power steering flow rate adjusting valve 25 and the power steering cylinder 16 in the oil passages 15 and 17 to prevent oil from leaking from the return oil passage 24 when the steering handle 9 is in the neutral position. And keep going straight.
[0011]
This steering device is configured as described above, and operates as follows when working in a normal field. When the steering handle 9 is turned to the right or left at an operation speed equal to or lower than the set speed, only a part (about 1/2) of the pressure oil passing through the power steering unit 12 is supplied to the power steering cylinder 16. The front wheels 2 and 2 are steered at a relatively slow speed. At this time, when the steering wheel 9 is rotated about two turns from the neutral position to the right or left, the steering angle of the front wheels 2 and 2 is maximized (portion A in FIG. 5). When the steering handle 9 is rotated to the right or left at an operation speed exceeding the set speed, the entire amount of pressure oil passing through the power steering unit 12 is supplied to the steering power steering cylinder 16, which is about twice that in the above case. The front wheels 2 and 2 are steered at a speed. Therefore, the steering angle of the front wheels 2 and 2 can be maximized (part B in FIG. 5) by turning the steering wheel 9 about one turn from the neutral position to the right or left, and quick turning is possible.
[0012]
When the vehicle speed exceeds the set speed, the steering is not accelerated even if the steering handle 9 is rotated at an operation speed exceeding the set speed, and a sudden turn during traveling on the road is prevented. Further, even when the engine speed is less than the set speed, it is determined that the engine is not working, so that the steering is not accelerated even if the steering handle 9 is rotated at an operation speed exceeding the set speed.
[0013]
In this steering apparatus, as shown in FIGS. 6 and 7, a hydraulic circuit unit 32 from the power steering unit 12 including the power steering flow rate adjusting valve 25 and the pilot check valves 31, 31 to the power steering cylinder 16 is connected to the power steering unit. By attaching it integrally with Hose 12, hoses, pipes, etc. are simplified and cost reduction is achieved.
[0014]
Next, FIG. 8 as a reference example to some phase differences from the present invention, represents the hydraulic circuit of the second example of the steering device. In this steering device, the pressure oil (power steering pressure oil) delivered from the hydraulic pump 10 is divided into two flows by the flow dividing valve 35, one flow sends pressure oil to the power steering unit 12, and the other flow is the power steering flow rate. Pressure oil is sent to the amplification valve 36 (opening / closing means). The power steering flow rate amplifying valve 36 has a neutral position for joining the pressure oil being sent to the other flow for sending the pressure oil to the power steering unit 12, and the right cylinder chamber 16 a of the power steering cylinder 16 via the right feed oil passage 37. And a left feed position for flowing to the left cylinder chamber 16b via the left feed oil passage 38. Since the power steering unit 12 has the same configuration as that of the first example, the description thereof is omitted.
[0015]
The power steering flow rate amplifying valve 36 is a solenoid valve. As shown in FIG. 9, the engine speed sensor 26 for detecting the engine speed, the vehicle speed sensor 27 for detecting the vehicle speed, and the operating speed of the steering handle 9 are detected . Based on the detection result of the steering sensor 28, drive output is output from the microcomputer 29 to the right steering solenoid 36a and the left steering solenoid 36b of the power steering flow amplifying valve 36. FIG. 10 is a flowchart of the control. When the vehicle speed is equal to or lower than the set speed, the engine speed is equal to or higher than the set speed, and the steering wheel operating speed is equal to or higher than the set speed, output is made to the solenoid 36a (or 36b) on the steering direction side. Then, the feed oil passage 37 (or 38) is opened, and when at least one of the above conditions is not satisfied, the feed oil passages 37 and 38 are kept closed without outputting to any of the solenoids 36a and 36b. I have control.
[0016]
This steering device is configured as described above, and operates as follows when working in a normal field. When the steering handle 9 is rotated to the right or left at an operation speed equal to or lower than the set speed, only the pressure oil passing through the power steering unit 12 is supplied to the steering power steering cylinder 16, and the front wheels are moved at a relatively slow speed. 2 and 2 are steered. At this time, when the steering wheel 9 is rotated about two turns from the neutral position to the right or left, the steering angle of the front wheels 2 and 2 is maximized (portion A in FIG. 5). When the steering handle 9 is rotated to the right or left at an operation speed exceeding the set speed, both the pressure oil passing through the power steering unit 12 and the pressure oil passing through the feed oil passage 37 (or 38) are used for steering. The power is supplied to the power steering cylinder 16 and the front wheels 2 and 2 are steered at a speed approximately twice that in the above case. Therefore, the steering angle of the front wheels 2 and 2 can be maximized (part B in FIG. 5) by turning the steering wheel 9 about one turn from the neutral position to the right or left, and quick turning is possible.
[0017]
As in the first example, when the vehicle speed exceeds the set speed or the engine speed is less than the set speed, the steering is not accelerated even if the steering wheel 9 is rotated at an operation speed exceeding the set speed. .
[0018]
In the first example, a return oil passage 24 for returning a part of the pressure oil that has passed through the power steering unit 12 to the oil tank 14 is provided, and the return oil passage is provided by a power steering flow rate adjustment valve 25 according to the operation speed of the steering handle 9. By opening and closing, the amount of pressure oil supplied to the power steering cylinder 16 is adjusted. Further, in the second example, feed oil passages 37 and 38 for directly sending pressure oil to the power steering cylinder 16 without passing through the power steering unit 12 are provided, and the feed oil passage amplifying valve is provided on the feed oil passage according to the operation speed of the steering handle 9. By opening and closing at 36, the amount of pressure oil supplied to the power steering cylinder 16 is adjusted. In any example, when a large amount of pressure oil is supplied to the power steering cylinder 16 and a sudden turn is performed, the operation of the steering handle 9 is reflected in the steering of the front wheels 2 and 2, so the course of the aircraft during the turn Even if there are obstacles, this can be avoided. In the illustrated example, the power steering flow rate adjustment valve 25 and the power steering flow rate amplification valve 36 are solenoid valves, and their operation is electrically controlled. However, these valves may be mechanically operated.
[0019]
Further, FIG. 11 shows a hydraulic circuit of a third example which is a reference example of the steering device. In this steering apparatus, the basic circuit configuration is the same as that of the second example, and the power steering flow rate amplifying valve 36 ′ is a proportional solenoid valve, and the power steering flow rate amplifying valve 36 ′ is opened according to the operating speed of the steering handle 9. The degree of control is adjusted so that the flow rate of the pressure oil supplied to the power steering cylinder 16 through the feed oil passage 37 (or 38) increases as the operation speed of the steering handle 9 increases. As a result, the steering speed does not change discontinuously at a certain steering wheel rotation speed as in the first and second examples, but the steering speed is continuously changed from the low speed range to the high speed range. It changes (part C of FIG. 5). The degree of change in the steering speed may be set in accordance with individual differences among operators.
[0020]
【The invention's effect】
As described above, the steering device for a mobile agricultural machine according to the present invention allows the entire amount of oil in the oil passage to pass between the oil passage between the power steering unit and the steering hydraulic actuator, and a part thereof. The opening / closing means (25) for switching to the state to be operated is provided, and the opening means is used for the turning operation of the airframe in which a state in which the vehicle speed is not more than the set speed and the handle speed is not less than the set speed is detected by the sensors (27, 28) Since the control means (29) for increasing the steering speed of the steered wheels (2, 2) is provided in such a state that the oil amount between the oil passages is fully communicated with each other (25), it becomes possible to turn quickly during the work. At the same time, it is now possible to prevent sudden turning when not working, such as when driving on the road.
[Brief description of the drawings]
FIG. 1 is a side view of a tractor.
FIG. 2 is a hydraulic circuit diagram of a first example of a steering device.
FIG. 3 is a block diagram of the control device.
FIG. 4 is a flowchart of the control.
FIG. 5 is a graph showing a relationship between a handle rotation speed and a handle rotation speed from neutral to maximum steering.
FIG. 6 is a diagram illustrating an arrangement of a steering device.
7A is a plan sectional view of a hydraulic circuit unit, and FIG. 7B is a side sectional view thereof.
FIG. 8 is a hydraulic circuit diagram of a second example of the steering device.
FIG. 9 is a block diagram of the control device.
FIG. 10 is a flowchart of the control.
FIG. 11 is a hydraulic circuit diagram of a third example of the steering device.
[Explanation of symbols]
1 Tractor 2 Front wheel 3 Rear wheel 5 Engine 9 Steering handle 10 Hydraulic pump (hydraulic supply source)
12 Power steering unit 14 Oil tank 16 Power steering cylinder (steering hydraulic actuator)
24 Return oil passage 25 Power steering flow control valve (opening / closing means)
36, 36 'Power steering flow rate amplifying valve (open / close means)
37, 38 Feed oil passage

Claims (1)

Steering system of the mobile agricultural machine provided with a power steering unit (12) for controlling the flow of the hydraulic fluid of the steering wheel (9) the hydraulic fluid supply source in response to the operation direction from (10) to the steering hydraulic actuator (16) A vehicle speed sensor (27) for detecting the vehicle speed of the mobile agricultural machine and a sensor (28) for detecting the operation speed of the steering handle (9) are provided, and the power steering unit (12) and the hydraulic actuator for steering (16 ) Is provided with an opening / closing means (25) for switching between a state in which the entire amount of oil in the oil passage is allowed to pass and a state in which a part thereof is allowed to pass, and the vehicle speed is set by the both sensors (27, 28). In the turning operation of the airframe in which the state where the steering wheel speed is equal to or higher than the set speed is detected, the opening means (25) is operated in such a state that the entire oil amount is communicated between the oil passages. Steering apparatus for a mobile agricultural machine which is characterized in that a wheel fast to the control means a steering speed of the (2,2) (29).

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