JPS61146678A - Front and rear wheel steering system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a steering device for front and rear wheels of a vehicle.

(Prior technology) As one of the four-wheel steering systems for vehicles, a lever that swings in conjunction with the steering wheel is disposed at the front of the vehicle body, and an arm that connects and supports tie rods for the left and right rear wheels is located in the middle. It is known that the arm is pivoted and one half of the arm is connected to the lever by a link. According to this, it is possible to steer the rear wheels in the opposite direction to the front wheels by steering the steering wheel,
A small turning radius is obtained, which improves maneuverability of the vehicle.

(Problem to be solved by the invention) However, the steering system has a so-called linear characteristic, in which the rear wheels are steered in the opposite direction to the front wheels even when the steering wheel is operated at a small steering angle. Because the steering wheel response in the vicinity is sharp, it becomes difficult to keep the vehicle going straight.

Therefore, an object of the present invention is to make the rear wheel steering characteristics non-linear by making some improvements to the above-mentioned steering system, so that when the steering wheel is operated at a small steering angle, the rear wheels can be almost steered in the same manner as in a normal front wheel steering vehicle. By operating the steering wheel at a large steering angle, the rear wheels can be relatively largely steered in the opposite direction to the front wheels to obtain a small turning radius, and the vehicle can be driven straight. To provide a steering device for front and rear wheels, which maintains the stability of the vehicle and also allows the vehicle to be moved diagonally left and right to easily perform width closing.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a lever (41) that is disposed at the front of the vehicle body and swings in conjunction with the handlebar, and a lever (41) that is pivotally supported at an intermediate portion and that is connected to the left and right sides. In a steering device for front and rear wheels, in which one half of an arm (47) that connects and supports a rear wheel tie rod is connected by a link (51), one of the lever (41) or the arm (47) and the link (51) ) and the crankshaft (
53), and a planetary gear mechanism is configured between the shaft portion (50) on the steering input side of the crankshaft (53) and the vehicle body side.

Specifically, the shaft portion on the steering input side of the crankshaft (53) (
An external gear (57) is fixedly provided on the vehicle body side so that the binion (5B) is engaged with the binion (5B) provided on the pinion 50, and whose axis is the pivot point of the lever (41) or arm (47). ) or internal gear (157
) constitutes a planetary gear mechanism.

(Example) Examples will be described in detail below based on the accompanying drawings.

FIG. 1 is a cutaway side view of a riding working machine, and FIG. 2 is a plan view of a steering system. In this embodiment, a riding working machine (1) such as an agricultural tractor is equipped with front and rear wheel steering devices.

The riding work machine (1) is equipped with an engine (3) with a crankshaft (0 being vertically mounted) in the front part of the frame (2), a mission case (5) is arranged in the rear part of the frame (2), The mission output shaft (8) and the crankshaft (4) are connected to the propulsion shaft (
8), place the seat (3) on the rear of the vehicle,
The vehicle body is equipped with front wheels (11), (11) and rear wheels (12), (12) of the same diameter on the front, rear, left and right sides of the vehicle body, and such a work vehicle can perform front and rear wheel steering by operating the handle (31), and has four wheels. It is possible to drive.

That is, the transmission case (13), (13) is disposed on both sides of the transmission case (5), and the input shaft thereof is interlocked with the output shaft of the differential provided in the transmission case (5). Reduction output shaft (14).

Attach the rear wheels (12) and (12) to (14). A differential case (15) is arranged below the engine (3), and the differential input shaft (16) and transmission output shaft (7) are connected by a propulsion shaft (17). Beam transmission cases (18), (18) are arranged, and the input shaft and the differential output shaft are interlocked, and the front wheels (11), (19) are connected to the reduction output shaft (19), (19).
1) Attach. In this way, the four-wheel drive system is configured and roars.

The four-wheel steering system is constructed as follows.

First, the front wheels (11), (11) are mounted on the shafts, and the transmission case (18), (Is) is mounted on the king pins (21), (2).
1) Provided with knuckle arms (22), (22) that can swing around and extend rearward, and the knuckle arms (22)
, (22) are connected to tie rods (23), (23) using ball joints (24), (24). Also rear wheel (12)
, (12) or transmission case (13),
(13) is also swingable around the king pins (28) and (2B), and the knuckle arms (27) and (2B) extend inwardly.
27) and a knuckle arm (27).

Connect the tie rod (28) and (28) to (27) with the ball joint (
29), connect at (29).

A gear box (
30, and this gear box (34) is connected to the engine (3
) located at the rear. At the front inside the gear box (34) is a binion (
35), a sector gear (36) meshing with this binion (35) is provided, and a support shaft (37) integrated with the sector gear (3B) is made to hang down and protrude below the gear box (30). ) is integrally provided with a lever (41).

This lever (41) has a flat bell crank shape,
Front wheel tie rods (23) are attached to the left and right ends of the half portion (42) that extends forward and is fixed to the support shaft (37) at the corner of the intermediate portion.
, (23) are connected and supported by ball joints (45) and (45). It also extends to the rear side of the lever (41).
A side U-shaped portion (40) is provided at the tip of the allogenous portion (43).

On the other hand, the frame (2) in front of the mission case (5)
A support shaft (48) is set up on the top, and an arm (47) in the shape of a flat bell crank is swingably supported on the support shaft (48) at a corner of the intermediate portion. The inner end portions of the rear wheel tie rods (28), (28) are connected and supported by ball joints (49), (49) to the tips of both measuring portions extending forward.

In the above, the support shaft (37) of the lever (41) and the support shaft (4B) of the arm (47) are both arranged on the center line of the vehicle body, and the tip of the right half of the arm (47) has a protruding part. Department (
48).

And this arm protrusion (48) has a linkage link (
51) are pivotally connected by a pin (52).

Further, as shown in FIGS. 3 and 4, the U-shaped portion (40) of the lever (41) and the front end of the link (51) are connected by a crankshaft (53). That is, the crankshaft (53) Upper and lower crank pins (54) with eccentric centers (e).

(55) is integrally formed with the lower crank pin (55).
5) pivots the front end of the link (51), thus making the link (51) intersect with the weight center line of the vehicle body, while the upper crank pin (54) is inserted longitudinally into the cone-shaped part (40). support,
A pinion (58) is integrally provided at the intermediate portion of the crank pin (50) facing into this U-shaped portion (40).

An external gear (57) meshed with the pinion (5B) is fixed to the lower surface of the gear box (30).The axis of this external gear (57) is aligned with the axis of the support shaft (37). It forms a sector gear type sun gear, and this sun gear (57) is attached to the lower surface of the gear box (30) with bolts (58).
)... to fix it. Therefore, the pinion (5B) forms a planetary pinion that rotates around the outer periphery of the sun gear (57).

The above planetary gear mechanism (5B), (57) and the crankshaft (
53) are initialized as follows.

First, the center point of the sun gear (57) in the neutral steering state (
01) and the center point (02) of the planetary pinion (58)
Connect the joint pin (51) with the link (51) on the straight line connecting the
55) to match the center point (P). That is, as shown in FIG. 5, which is initially set diagrammatically, (Rt) is the standard pitch circle radius of the sun gear (57), and (R2) is the pinion (57).
6) is the standard pitch circle radius, (R3) is the pinion (5B
) is the eccentricity of the joint pin (55) with respect to (
α) is the rotation angle of the lever (41) from the neutral position.

If we take the orthogonal coordinate system that intersects at point (01), it will be as shown in Figure 6, and from the condition of an epicycloid, R1α=R2θ,°, θ=(R+/Rz)α...(1
) Therefore, the coordinates of point (02) are Xl = (Rt +l'12) cosa =
(II) Y r = (Rt + R2) sin α
-(m) Next, find the relative coordinates of point (P) with respect to point (02).

First, if R3=R2, that is, point (P) coincides with the reference pitch circle of the pinion (56), then as is clear from FIG. 7, X = -R2cog(a+θ) -(iV)
Y = −R2gin(a10) ・(v
) and the coordinates of point (P) with respect to point (Ol) are X=+X
l +x, y=yl +Y, so x= (R1
10fL2)cos(E-It2cot(a+θ)V=
(Rt + R2) sin α - R2 sin (α 10) Substituting equation (1) into this, the value of y in equation (Vl) is almost lever (41)
This is the control stroke of the joint pin (55) at the rotation angle (α).

In addition, when the point (P) is not made to coincide with the reference pitch circle of the pinion (5B), that is, when the center point of the joint pin (55) is set as the point (po), the above-mentioned (iV) and (V).

Equations (vl) and (vi) are as follows.

X=-R3cos(a+0)...(X
FIG. 8 shows the locus of the center point (P) or (Po) of the joint pin (55). Here, R, = 76.5, R2 = 12, and if R3 = 17, the trajectory is (A), and if R3 = 12, the trajectory is (B).
, when R2=8, a trajectory (C) is drawn.

Furthermore, the steering characteristics of the rear wheels (12), (12) corresponding to each trajectory are shown in FIG. Here, the operating angle of the lever (can) is ±38.5°, the linear characteristic (L) shows the conventional characteristic, and the area (A) and (B) shows the anti-phase steering of the front and rear wheels. ), (d) represent in-phase steering.

As is clear from this characteristic diagram, R,>R,.

That is, the center of the joint pin (55) is connected to the pinion (5B).
When set outside the reference pitch circle, that is, the center point (
In the case of Po), it is possible to slightly steer the rear wheels (12), (12) in the same direction as the front wheels (11), (11) within a small steering angle range of the steering wheel (31), causing the vehicle to turn diagonally. It can be moved in the left and right directions, making it easy to bring it closer together.

When R3≦R2, that is, the center of the joint pin (55) is set inside the reference pitch circle of the pinion (58), that is, when the center point (P) is set, the handle (
In the small steering angle range of 31), the rear wheels (12), (12) are hardly turned, and the vehicle can maintain straight travel equivalent to a normal front wheel steered vehicle.

Also, in any case, the rear wheels (12), (12) can be largely steered in the opposite direction to the front wheels (o), (11) in the large steering angle range of the handle (31), so the turning radius is small. is obtained, and the maneuverability of the vehicle is improved.

The abduction cycloid has been explained above, but the adduction cycloid will be explained first.

In this embodiment, as shown in FIGS. 10 and 11, an internal gear (157) with which the pinion (56) meshes is fixed to the lower surface of the gear box (30). This internal gear (157) supports the shaft center. This internal gear (1) forms an arc-shaped ring gear aligned with the axis of the shaft (37).
57) to the gear box (pole on the bottom of 30) (158)
- Fix at... Therefore, the pinion (58) forms a planetary pinion that rotates around the inner circumference of the internal gear (157).

The above initial settings of the planetary gear mechanism (5B), (157) and crankshaft (53) are the center point (01) of the internal gear (157) and the link (51) in the neutral steering state.
This is done by aligning the center point (0,) of the planetary pinion (58) with the center point (P) of the joint pin (55).

Also, as shown in Fig. 12, the internal gear (157)
This is the same as above except that the reference pitch circle radius of is set to (R+), and the above-mentioned conditional expressions also hold true with this internal rotation cycloid system.

Then, the locus of the center point of the joint pin (55) is
Figure 14 shows the steering characteristics of the rear wheels (12), (12) corresponding to their respective trajectories, where R, = 88.5, and the trajectory and characteristics (A) are R2 = 12 , when Rz=17, (B) when R2=R3=12, (C) when R,=
12, in the case of R3=8, and (D) is R2=R3=8
This is the case.

It can thus be seen that the adduction cycloid method can also provide the same effects as the above-mentioned epicycloid method.

By the way, in the above embodiment, the lever (41) and the link (
Although the crankshaft (53) and the planetary gear mechanism (5B), (5?), (157) are configured at the connection between the link (51) and the arm (47), the same structure is used at the connection between the link (51) and the arm (47). In that case, a planetary gear mechanism is constructed on the steering input side of the crankshaft, that is, on the crank pin with the link (51) and on the vehicle body side.

It goes without saying that the steering device for one or more front and rear wheels is applied not only to a work vehicle but also to a general vehicle such as a passenger car.

(Effects of the Invention) As described above, according to the present invention, the lever that is disposed at the front of the vehicle body and swings in conjunction with the steering wheel, and the lever that is pivotally supported at the intermediate portion and connects and supports the tie rods for the left and right rear wheels. In a steering device for front and rear wheels, in which a lever or one half of an arm is connected by a link, the lever or one of the arms and the link are connected by a crankshaft, and the shaft part on the steering input side of the crankshaft and the vehicle body side are connected by a crankshaft. Since the planetary gear mechanism is configured in this way, it is possible to realize nonlinear rear wheel steering characteristics with a relatively simple structure.

Therefore, when the steering wheel is operated at a small steering angle, the rear wheels can hardly be steered or the rear wheels can be slightly steered in the same direction as the front wheels, similar to a normal front wheel steering vehicle, while when the steering wheel is operated at a large steering angle, the rear wheels can be steered slightly in the same direction as the front wheels. The front wheels can be steered by a relatively large amount in the opposite direction.

A small turning radius is obtained, which improves the maneuverability of the vehicle, and it also becomes easier to keep the vehicle running straight, and it also becomes possible to move the vehicle diagonally left and right to easily pull over.

[Brief explanation of the drawing]

Figure 1 is a cutaway side view of the riding work machine, Figure 2 is a plan view of the steering system, Figure 3 is an enlarged side view of the main parts, Figure 4 is the same plan view, and Figure 5 is a diagrammatic representation. 6 is a diagram showing the relative coordinates of the center point of the joint pin with respect to the center point of the external gear; FIG. 7 is a diagram showing the relative coordinates of the center point of the joint pin with respect to the center point of the pinion; Figure 8 is a locus diagram of an epicycloid, Figure 9 is a rear wheel steering characteristic diagram, Figure 10 is an enlarged side view of the main part showing the second embodiment, Figure 11 is a plan view of the same, and Figure 12 is a line diagram. Fig. 13 is a plan view of the main part shown in Figure 13 is a locus diagram of an adduction cycloid, Fig. 14
The figure is a rear wheel steering characteristic diagram. In one drawing, (11) is the front wheel, (12) is the rear wheel, and (23)
is the tie rod for the front wheel, (28) is the tie rod for the rear wheel, (
31) is the handle, (30 is the gear box, (35) is the pinion, (36) is the sector gear, (37) is the spindle,
(41) is the lever, (4B) is the support shaft, (47) is the arm, (51) is the link (53) is the crankshaft, (50 is the shaft on the steering input side, (55) is the joint pin, (5B)
) is a planetary pinion, (57) is an external gear, and (157) is an internal gear. Patent Applicant Honda Motor Co., Ltd. Agent Patent Attorney 1) Kuni Ohashi, Patent Attorney, Part 1, Yu Koyama, Patent Attorney, Part 6, Figure 7

Claims (2)

[Claims] (1) A lever that swings in conjunction with the handlebar is disposed at the front of the vehicle body, and an arm that connects and supports the tie rods for the left and right rear wheels is pivoted at the intermediate part, and one half of the arm and the lever are connected. In a vehicle steering system that is connected by a link, the rear wheels are steered along with the front wheels by steering operation of the steering wheel.
A steering device for front and rear wheels, characterized in that one of the lever or the arm and a link are connected by a crankshaft, and a planetary gear mechanism is constructed between a shaft portion on a steering input side of the crankshaft and a vehicle body side. (2) The planetary gear mechanism is fixed to the vehicle body so that the pinion meshes with a pinion provided on the shaft portion on the steering input side of the crankshaft, and the shaft center is the pivot point of the lever or arm. A steering device for front and rear wheels according to claim 1, comprising an external gear or an internal gear.