JPH07108666B2 - Front wheel steering Steering system for all-wheel drive type self-propelled vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering method and device for a front wheel steering all-wheel drive type self-propelled vehicle such as a speed sprayer, and more specifically, while securing a small turn at low speed. The present invention relates to a steering method and device for a front wheel steering all-wheel drive type self-propelled vehicle capable of smoothly turning at high speed.

[Conventional technology]

A self-propelled vehicle for agriculture, such as a speed sprayer, adopts an all-wheel drive system in order to ensure drivability in soft ground.

Further, in the conventional agricultural self-propelled vehicle, the steering system is either the Ackermann steering type or the parallel steering type, and it is difficult to switch between the Ackermann steering type and the parallel steering type.

[Problems to be Solved by the Invention]

In the case of the Ackermann steering type, there is an advantage that the turning center of the outer wheel and the inner wheel coincide with each other at the time of turning, and the tire can turn without causing skidding. Since the speed sprayer travels at a high speed when reciprocating to the field and moving to the water drawing field, the Ackermann steering type is advantageous in such a high speed travel.

On the other hand, when the Ackermann steering type is adopted for the speed sprayer, the turning angle of the outer wheel is smaller than that of the inner wheel when turning sharply, so that the driving torque on the outer wheel side becomes large and the turning radius increases. There is.
Especially for agricultural self-propelled vehicles, one-brake is used to further reduce the turning radius beyond the turning angle of the steered wheels, which is a major disadvantage when the agricultural self-propelled vehicle is of the Ackermann steering type. Becomes

It is an object of the inventions of claims 1 and 2 to provide a front-wheel steering all-wheel drive type self-propelled vehicle which is used to solve the problem at the time of a sharp turn while ensuring the convenience at the time of high speed traveling by the Ackerman steering type. A steering device is provided.

Another object of the invention of claim 2 is to further reduce the operation force required for the switching operation between the Ackermann steering and the non-Ackermann steering.

[Means for Solving the Problems]

The present invention will be described using the reference numerals of the drawings corresponding to the embodiments.

A steering device of a front wheel steering all-wheel drive type self-propelled vehicle (10) according to claim 1 has the following components (a) to (c).

(A) When the length is fixed, the left and right front wheels (12) are joined together so that the left and right front wheels (12) are steered at the Ackermann steering angle. Then, the second retractable joint that connects the left and right front wheels (12) so that the turning angle of the outer wheel is larger than the Ackermann steering angle.
The tie rods (56) (c) of the first tie rod (54) and the second tie rod (56) are fixed and extendable at the time of high speed traveling and the first tie rod (at the time of low speed traveling, respectively) at the time of high speed traveling. 54) The steering member of the front wheel steering all-wheel drive type self-propelled vehicle (10) according to claim 2, wherein the second tie rod (56) is extendable and retractable and the length is fixed. Fixed and switchable hydraulic cylinders (58, 60) are arranged on the first tie rod (54) and the second tie rod (56). Also, operating members (62)
An oil pressure switching valve (66) is provided which is operated by the switch to switch between expansion and contraction and fixed length of the hydraulic cylinders (58, 60).
This hydraulic pressure switching valve (66) is used when the hydraulic cylinders (58, 60) are retractable and fixed in length.
The oil chambers (80, 82) on both sides of the piston (78) in (0) are respectively brought into communication and non-communication.

[Action]

In the invention of claim 1, according to high speed traveling and low speed traveling,
When the operating member (62) is switched, the first tie rod (54) and the second tie rod (56) can be fixed in length and extendable / contractible during high-speed traveling. As a result, the transmission of the steering force between the left and right front wheels (12) is performed by the first tie rods (54), and the left and right front wheels (12) are steered at the Ackermann steering angle to match the turning centers. On the other hand, when traveling at low speed, the first tie rod (54) and the second tie rod (54)
The tie rods (56) are extendable and fixed in length. As a result, the steering force is transmitted between the left and right front wheels (12) by the second tie rods (56), and the left and right front wheels (12) have a non-Ackermann steering angle at which the outer wheels have a larger turning angle than the Ackermann steering angle. Steered. As a result, the difference in driving torque between the outer wheel side and the inner wheel side of the left and right front wheels (12) decreases, and the turning angle on the outer wheel side increases, and the turning radius of the front wheel steering all-wheel drive type self-propelled vehicle (10) Decreases.

In the invention of claim 2, the hydraulic pressure switching valve (66) is operated by the operating member (62) to communicate the oil chambers (80, 82) on both sides of the piston (78) in the hydraulic cylinder (58, 60). And control non-communication. The hydraulic cylinders (58,60) in which both oil chambers (80,82) communicate with each other absorb the hydraulic pressure between both oil chambers (80,82), and the hydraulic cylinders (58,60) can expand and contract. The first tie rod (54) or the second tie rod (56) on which the hydraulic cylinders (58, 60) are arranged can also be expanded and contracted. On the other hand, the hydraulic cylinder (58, 60) in which both oil chambers (80, 82) communicate with each other is
82), the suction and discharge of hydraulic pressure is stopped, and the hydraulic cylinder (58,6
0) has a fixed length, and the second tie rod (56) or the first tie rod (54) on which the hydraulic cylinder (58, 60) is arranged also has a fixed length.

〔Example〕

 Hereinafter, the present invention will be described with reference to the embodiments of the drawings.

FIG. 7 is a side view of the speed sprayer 10. The speed sprayer 10 is provided with a frame 16 which is supported by front wheels 12 and rear wheels 14 and is self-propelled. On the upper side of the frame 16, a driver's seat 18 and a chemical solution are stored in order from the front of the speed sprayer 10. Chemical tank 20, engine 28 described later
The hood 22 that encloses the engine room that houses the engine room, the spout 24 that sprays the chemical liquid, and the spout that sucks air from the rear.
A blower 26 for discharging to 24 is installed.

FIG. 3 is a configuration diagram of a power transmission system and a steering system of the speed sprayer 10. Rotational power of the engine 28 is transmitted to the transmission 32 via the clutch 30 and is distributed to the front and rear propeller shafts 34, 36 in the transmission 32. The rotary power distributed to the propeller shaft 34 is transmitted to the left and right front wheels 12 via the front differential device 38, and the rotary power distributed to the propeller shaft 36 is transmitted to the left and right rear wheels 14 via the rear differential device 40. . The steering wheel 42 is arranged in the driver's seat 18, and the steering force of the steering wheel 42 is transmitted to the right knuckle arm 48 via the gear box 44 and the drag link 46. The left knuckle arm 48 is rotatably supported around the kingpin 50 and rotates integrally with the front wheel 12 and the tie rod arm 52. Tie rod arm 52 is knuckle arm 48
The first tie rod 54 for Ackerman steering and the second tie rod 56 for parallel steering, which project further rearward, extend in the left-right direction and are rotatably coupled to the tie rod arm 52 at both ends. First hydraulic cylinder
The 58 and the second hydraulic cylinder 60 are arranged in the middle of the first tie rod 54 and the second tie rod 56, respectively.
The tie rod 54 and the second tie rod 56 of FIG. The switching lever 62 is swingably arranged in the driver's seat 18 and switches the transmission 32 between a high speed gear and a low speed gear via a connecting rod 64. The hydraulic pressure switching valve 66 includes a first hydraulic cylinder 58 and a second hydraulic cylinder via pipelines 68 and 70, respectively.
It is connected to 60, and the position can be switched by the switching lever 62 via the operating rod 72.

Figure 4 shows the left and right tie rod arms 52 and the first tie rod.
FIG. 6 is a plan view showing a connection relationship between 54 and a second tie rod 56. The first tie rod 54 and the second tie rod 56 are rotatably coupled at both left and right ends via ball ends 74. FIG. 4 shows the positional relationship during straight traveling, in which the first tie rod 54 and the second tie rod 56 extend in the left-right direction in parallel with each other. In Figure 4, L1
Is the distance between the left and right kingpins 50, L2 is the first tie rod 54
, L3 is the length of the second tie rod 56, L4 is the longitudinal distance between the kingpin 50 and the first tie rod 54, and L5 is the longitudinal distance between the kingpin 50 and the second tie rod 56. Ball end of kingpin 50 and first tie rod 54
The two straight lines that connect with 74 intersect at the midpoint O of the left and right rear wheels 14. The first tie rod 54 is disposed rearward of the second tie rod 56, and L1 = L3, L2 <L3, L4> L5.

FIG. 5 is a structural diagram of the first tie rod 54 and the second tie rod 56 as seen from the rear of the speed sprayer 10. The first tie rod 54 and the second tie rod 56 are the same in structure but only different in length. In the first hydraulic cylinder 58 and the second hydraulic cylinder 60, a piston 78 is slidably slidably contacted in a case 76, and oil chambers 80 and 82 are defined on the left and right sides of the piston 78, respectively. The left and right rods 84 are fixed to the piston 78 and the case 76, respectively, at one end,
The other end is fixed to the tie rod end 86. O
The ring 79 and the O-ring 81 seal the peripheral portion of the piston 78 and the penetrating portion of the left rod 84 in the case 76, respectively. The tie rod end 86 is rotatably fitted to the ball end 74, and the bolt 88 is a ball end in the vertical direction.
The ball end 74 is fixed to the tie rod arm 52 by penetrating the 74 and the tie rod arm 52 and screwing a nut 90 at the lower end.

FIG. 6 shows a first hydraulic cylinder 58 and a second hydraulic cylinder.
It is a hydraulic circuit diagram of 60. The pipe line 68 and the pipe line 70 communicate with the left and right oil chambers 80 and 82 of the first hydraulic cylinder 58 and the second hydraulic cylinder 60, respectively. The hydraulic switching valve 66
The position is switched by the switching lever 62 via the operation rod 72, and one and the other of the oil chambers 80, 82 are disconnected and in contact with each other. In FIG. 6, the pipe line 68 and the pipe line 70 are disconnected and in contact with each other, and the first hydraulic cylinder 58 has the oil chambers 80, 82.
The second hydraulic cylinder 60 is allowed to suck and drain the hydraulic pressure between the oil chambers 80 and 82 while being prevented from sucking and draining the hydraulic pressure between them and fixed in length. Contrary to FIG. 6, when the pipe line 68 and the pipe line 70 are connected and disconnected, respectively,
The first hydraulic cylinder 58 is expandable and contractable, and the second hydraulic cylinder 60 is fixed in length.

1 and 2 show the steering system in the turning states of high speed running and low speed running, respectively. 1 and 2
The operation of the embodiment will be described with reference to the drawings.

When the speed sprayer 10 is driven at high speed (Fig. 1), such as when returning to and from a farm or a water fetching place, the driver's seat 18
The driver sets the switching lever 62 to the high speed position. As a result, the transmission 32 is switched to the high speed gear, and the front wheels 12 and the rear wheels are changed.
14 rotates at high speed. On the other hand, the hydraulic pressure switching valve 66 has the conduits 68, 7
The positions are set to 0 and 0 respectively, the first hydraulic cylinder 58 and the second hydraulic cylinder 60 are fixed in length and extendable, respectively, and the first tie rod 54 and the second tie rod 56 are respectively set in length. It can be fixed and stretched. The length of the first tie rod 54 is fixed to L2, and as a result, the steering force is transmitted between the left and right front wheels 12 by the first tie rod 54, so that the left and right front wheels 12 receive the Ackermann steering angle (inward in the turning direction). And the steering angles on the outer side are α and β, respectively, and α> β), and the turning centers are matched and the vehicle turns.

When running the speed sprayer 10 at a low speed (Fig. 2), such as when spraying a chemical solution in the field, the driver's seat 18
The driver sets the switching lever 62 to the low speed position. As a result, the transmission 32 is switched to the low speed gear, and the front wheels 12 and the rear wheels are changed.
14 rotates at low speed. On the other hand, the hydraulic pressure switching valve 66 has the conduits 68, 7
The positions of 0 and 0 are respectively contacted, the first hydraulic cylinder 58 and the second hydraulic cylinder 60 are extendable and fixed in length, respectively, and the first tie rod 54 and the second tie rod 56 are extendable and retractable, respectively. And the length is fixed. The length of the second tie rod 56 is fixed to L3, and as a result, the steering force is transmitted between the left and right front wheels 12 by the second tie rod 56, so that the left and right front wheels 12 have parallel steering angles (inward in the turning direction). And the outside steering angle is α)
And the steering angle α of the front wheel 12 on the outside in the turning direction is
It becomes larger than the Ackermann steering angle β and becomes equal to the steering angle of the inner front wheel 12. As a result, the turning radius of the speed sprayer 10 is reduced. At this time, the driver can further reduce the turning radius by using the one-side braking operation for braking only the front wheels 12 and the rear wheels 14 on the inside in the turning direction.

In the illustrated embodiment, the parallel steering is shown as the non-Ackerman steering, but the non-Ackerman steering at low speed traveling to which the present invention is applicable is not limited to the parallel steering, and the turning angle of the outer wheel when turning is Ackerman steering. Other non-Ackerman steering having a non-Ackermann steering angle larger than the steering angle may be used.

Further, in the illustrated embodiment, the speed sprayer 10 has two rear wheels 14, and the speed sprayer 10 is four-wheel drive. However, there are two or more rear wheels 14 on each side, and the total number of wheels is four. There are 10 more speed sprayers,
The present invention is applied to an all-wheel drive type self-propelled vehicle including four-wheel drive.

〔The invention's effect〕

In the invention of claim 1, the front wheel steering all-wheel drive type self-propelled vehicle is
While steering at high speed and low speed, the Ackerman steering and the non-Ackerman steering, in which the turning angle of the outer wheel is larger than the Ackerman steering angle, respectively, ensure smooth turning during high speed running,
It is possible to reduce the turning radius when traveling at low speed.

In the invention of claim 2, the hydraulic cylinders are disposed on the first tie rod and the second tie rod, the operating member operates the hydraulic switching valve, and the hydraulic pressure is switched to the hydraulic cylinder by the hydraulic switching valve, whereby Ackermann steering and Since the non-Ackermann steering can be switched, the operating force of the operating member can be reduced.

[Brief description of drawings]

The drawings relate to an embodiment of the present invention, and FIGS. 1 and 2 are views showing a steering system in a turning state of high speed traveling and low speed traveling, respectively, and FIG. 3 is a configuration diagram of a power transmission system and a steering system of a speed sprayer, FIG. 4 is a plan view showing the connecting relationship between the left and right tie rod arms and the first and second tie rods, and FIG. 5 is a structural diagram of the first and second tie rods seen from the rear of the speed sprayer. FIG. 6 is a hydraulic circuit diagram of the first hydraulic cylinder and the second hydraulic cylinder, and FIG. 7 is a side view of the speed sprayer. 10 …… Speed sprayer (front wheel steering all-wheel drive type self-propelled vehicle), 12 …… front wheel, 54 …… first tie rod, 56 …… second tie rod, 58 …… first hydraulic cylinder (hydraulic cylinder) , 60 …… Second hydraulic cylinder (hydraulic cylinder),
62 …… Switching lever (operating member), 66 …… Hydraulic switching valve, 78
...... Piston, 80,82 …… Oil chamber.

Claims (2)

[Claims] 1. A retractable first tie rod (54) for connecting left and right front wheels (12) so that the left and right front wheels (12) are steered at an Ackermann steering angle when the length is fixed.
And, when the length is fixed, the second tie rod (56) that expands and contracts to connect the left and right front wheels (12) so that the turning angle of the outer wheel becomes a non-Ackerman steering angle that is larger than the Ackerman steering angle, and high / low speed switching. At the same time, the length of the first tie rod (54) and the length of the second tie rod (56) can be fixed and the length of the second tie rod can be extended and contracted during high speed traveling, and the first tie rod (54) and the second tie rod ( A steering device for a front wheel steering all-wheel drive type self-propelled vehicle, characterized in that it has an operating member (62) that can be expanded and contracted and fixed in length. 2. A switchable hydraulic cylinder (58, 60) which can be expanded and contracted and fixed in length is disposed on the first tie rod (54) and the second tie rod (56), and the operating member (62).
Is provided with a hydraulic switching valve (66) for switching between expansion and contraction and fixed length of the hydraulic cylinder (58,60). The hydraulic switching valve (66) includes the hydraulic cylinder (58,6).
0) when it is telescopic and fixed in length, the oil chambers (80, 8) on both sides of the piston (78) in the hydraulic cylinder (58, 60) are fixed.
The steering device for a front wheel steering all-wheel drive type self-propelled vehicle according to claim 2, wherein 2) is set to a communication state and a non-communication state, respectively.