JPH0224379Y2 - - Google Patents

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 art) As one of the four-wheel steering systems for vehicles, a lever that swings in conjunction with the steering wheel is provided 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 becomes possible to steer the rear wheels in the opposite direction to the front wheels by steering the steering wheel, thereby obtaining a small turning radius and improving maneuverability of the vehicle.

(Problem that the invention aims to solve) However, because 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 with a small steering angle, it is difficult to drive in general, especially when driving straight. Because the steering wheel response in the vicinity is sharp, it becomes difficult to keep the vehicle going straight.

Therefore, the purpose 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 turned almost as much as in a normal front wheel steering vehicle. The front and rear wheels are designed so that they do not steer, and when the steering wheel is operated at a large steering angle, the rear wheels are steered by a relatively large amount in the opposite direction to the front wheels, allowing a small turning radius to be obtained while maintaining straight-line performance. to provide steering equipment.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a lever 41 that is disposed at the front of the vehicle body and swings in conjunction with the handlebar.
and a half part of an arm 47 which is pivotally supported at the intermediate part and connects and supports tie rods for the left and right rear wheels.
1, one of the lever 41 or the arm 47 and the link 51 are connected by a crankshaft 53, and the crankshaft 5
3 is rotatably supported on one of the lever 41 or the arm 47 and the link 51, and a pinion 56 is integrally provided on the shaft portion 54 on the steering input side of the crankshaft 53 and meshes with the pinion 56. An external gear 57 or an internal gear 157 is fixedly provided on the vehicle body side, and the shaft of the shaft portion 55 on the steering output side of the crankshaft 53 is connected to the shaft of the crankshaft 53 in a plan view. It is characterized in that the center is located inside the pitch circle including the reference pitch circle of the pinion 56.

Specifically, the initial setting in the steering neutral state in which the front wheels 11 and the rear wheels 12 are both facing in the straight-ahead direction is performed as follows or as follows.

When the external gear 57 is employed, the axis of the shaft portion 55 on the steering output side of the crankshaft 53 is aligned with the straight line connecting the axes of the external gear 57 and the pinion 56.

When the internal gear 157 is adopted, the internal gear 157 and the crankshaft 53
The axis of the pinion 56 is aligned with the straight line connecting the axes of the shaft portion 55 on the steering output side.

(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 vertical crankshaft 4 mounted on the front part of a frame 2, a transmission case 5 is arranged at the rear part of the frame 2, and a transmission input shaft 6 and a crankshaft 4 are connected to each other. They are connected by a propulsion shaft 8, a seat 9 is placed on the rear part of the vehicle body, and front wheels 11, 11 with the same diameter and a rear wheel 1 are mounted on the front, rear, left and right sides of the vehicle body.
2, 12, such a work vehicle has a handle 31
Front and rear wheel steering can be performed by operating the , and four-wheel drive is possible.

That is, reduction cases 13, 13 are disposed on both sides of the transmission case 5, and the input shaft thereof and the output shaft of the differential provided in the transmission case 5 are interlocked and connected, and the reduction output shafts 14, 14 are connected to each other.
Attach the rear wheels 12, 12 to the. and engine 3
A differential case 15 is disposed below, and connects a differential input shaft 16 and a transmission output shaft 7 with a propulsion shaft 17. Further, reduction cases 18, 18 are disposed on both sides of the differential case 15, and the input shaft The reduction output shaft 1 is connected and interlocked with the differential output shaft.
Attach the front wheels 11, 11 to 9, 19. A four-wheel drive system is thus constructed.

The four-wheel steering system is constructed as follows.

First, the reduction cases 18, 18 bearing the front wheels 11, 11 are made swingable around the king pins 21, 21, and the knuckle arms 22, which extend rearward,
22 is provided, and tie rods 23, 23 are connected to the knuckle arms 22, 22 by ball joints 24, 24. Further, the reduction cases 13, 13 bearing the rear wheels 12, 12 are also swingable around the king pins 26, 26, and the knuckle arms 2 extending inwardly.
7, 27 are provided, and tie rods 28, 28 are connected to the knuckle arms 27, 27 by ball joints 29, 29.

A gearbox 34 is provided at the bottom of the handle column 33 through which the steering shaft 32 of the handle 31 passes longitudinally, and this gearbox 34 is connected to the engine 3.
Placed at the rear. A pinion 35 that rotates in conjunction with the steering shaft 32 is disposed in the front part of the gear box 34, a sector gear 36 that meshes with the pinion 35 is provided, and a support shaft 37 integrated with the sector gear 36 hangs downwardly and protrudes below the gear box 34. let A lever 41 is integrally provided on the protrusion of this support shaft 37.

This lever 41 has a substantially bell-crank shape when viewed from above, and is fixed to the support shaft 37 at the corner of the intermediate portion, and connects the inner ends of front wheel tie rods 23, 23 with ball joints on the left and right sides of the tip of a half portion 42 extending forward. Connect and support at 45,45. Further, a side U-shaped portion 44 is provided at the tip of the other half portion 43 extending toward the rear side of the lever 41 .

On the other hand, the frame 2 in front of the transmission case 5
A support shaft 46 is set up on the support shaft 46, and an arm 47 having a substantially bell-crank shape in plan view is pivotally supported at the corner of the intermediate portion thereof, and a tip portion extending forward on both sides of the arm 47 is attached to the support shaft 46. The inner ends of the rear wheel tie rods 28, 28 are connected and supported by ball joints 49, 49.

In the above, the support shaft 37 of the lever 41 and the support shaft 46 of the arm 47 are both arranged on the width center line of the vehicle body, and the right half of the arm 47 has a protrusion 4 at its tip.
8 will be provided.

A linkage link 51 is pivotally connected to this arm protrusion 48 by a pin 52.

Furthermore, as shown in FIGS. 3 and 4, the lever 4
The U-shaped portion 44 and the front end of the link 51 are connected by a crankshaft 53. That is, the crankshaft 53 has upper and lower crank pins 54, 55 whose shaft centers are eccentric e.
The front end of the link 51 is pivotally supported by the lower crank pin 55, and thus the link 51
intersects with the width center line of the vehicle body, while an upper crank pin 54 is longitudinally supported in the U-shaped portion 44, and a pinion 56 is integrally provided at the middle portion of the crank pin 54 facing inside the U-shaped portion 44. .

An external gear 57 with which the pinion 56 meshes is fixed to the lower surface of the gear box 34. This external gear 57 forms a sector gear type sun gear whose axis is aligned with the axis of the support shaft 37,
This sun gear 57 is fixed to the lower surface of the gear box 34 with bolts 58. Therefore, the pinion 56 forms a planetary pinion that rotates around the outer periphery of the sun gear 57.

The above planetary gear mechanism 56, 57 and crankshaft 5
Perform the initial settings in step 3 as follows.

First, the center point (P) of the joint pin 55 with the link 51 is aligned with the straight line connecting the center point (O ₁ ) of the sun gear 57 and the center point (O ₂ ) of the planetary pinion 56 in the neutral steering state. That is, initial settings are made as shown diagrammatically in FIG. In the figure, (R ₁ ) is the standard pitch circle radius of sun gear 57, (R ₂ )
is the reference pitch circle radius of the pinion 56, (R ₃ ) is the eccentricity of the joint pin 55 with respect to the pinion 56, and (α) is the rotation angle of the lever 41 from the neutral position.

If we take the orthogonal coordinate system that intersects at the point (O ₁ ), it will look like Figure 6, and from the epicyclic cycloid condition, R ₁ α=R ₂ θ ∴ θ=(R ₁ /R ₂ ) α …(i) _{Therefore ,} the coordinates _{of point (} O _{2 ) are} Find relative coordinates.

First, if R ₃ = R ₂ , that is, point (P) coincides with the reference pitch circle of the pinion 56, then as is clear from Fig. 7, X = -R ₂ cos (α + θ) ... (iv) Y = - R ₂ sin (α+θ) …(v) And the coordinates of point (P) with respect to point (O ₁ ) are expressed as x=x ₁ +X, y=y ₁ +Y, so x=(R ₁ +R ₂ )cosα− R ₂ cos (α + θ) y = (R ₁ + R ₂ ) sin α − R ₂ sin (α + θ) Substituting equation (i) into this, x = (R ₁ + R ₂ ) cos α − R ₂ cos {(R ₁ + R ₂ /R ₂ )α} …(vi) y=(R ₁ +R ₂ ) sinα−R ₂ sin {(R ₁ +R ₂ /R ₂ ) α} …(vii) From the above, y in equation (vii) The value is approximately the control stroke of the joint pin 55 at the rotation angle (α) of the lever 41.

In addition, if the point (P) is not made to coincide with the reference pitch circle of the pinion 56, that is, if the center point of the joint pin 55 is set to the point (P'), the above (iv), (v),
Equations (vi) and (vii) are as follows.

X = -R ₃ cos (α + θ) ... () Y = -R ₃ sin (α + θ) ... () x = (R ₁ + R ₂ ) cos α - R ₃ cos {(R ₁ + R ₂ / R ₂ ) α} ... () y = (R ₁ + R ₂ ) sin α − R ₃ sin {(R ₁ + R ₂ / R ₂ ) α} ... () And if we express the locus of the center point (P) or (P') of the joint pin 55, then As shown in Figure 8.
Here, R ₁ = 76.5, R ₂ = 12, and if R ₃ = 17, the trajectory (A), if R ₃ = 12, the trajectory (B), and if R ₃ = 8, the trajectory (C). draw.

Further, the steering characteristics of the rear wheels 12, 12 corresponding to each locus are shown in FIG. 9. Here lever 4
The angle used in No. 1 is ±38.5 degrees, the linear characteristic (L) shows the conventional characteristic, and regions A and B represent anti-phase steering of the front and rear wheels, and regions C and D represent in-phase steering.

As is clear from this characteristic diagram, when R ₃ ≦ R ₂ , that is, when the center of the joint pin 55 is set inside the reference pitch circle of the pinion 56 , that is, when the center point (P) In the small steering angle range, the rear wheels 12, 12 are hardly steered, and the vehicle can maintain straight travel equivalent to a normal front wheel steered vehicle.

As described above, in the present invention, the center of the joint pin 55 forming the shaft portion on the steering output side is made to coincide with the reference pitch circle of the pinion 56 or to be located inside the pitch circle.

On the other hand, when R ₃ > R ₂ , that is, when the center of the joint pin 55 is set outside the reference pitch circle of the pinion 56, that is, when the center point (P'), the rear wheel 12 is , 12 as front wheel 1
It becomes possible to slightly turn the vehicle in the same direction as 1 and 11, and the vehicle can be moved diagonally to the left and right, making it possible to easily perform width closing, etc.

In either case, the rear wheels 12, 12 can be largely steered in the opposite direction to the front wheels 11, 11 in the large steering angle range of the steering wheel 31, so a small turning radius is obtained, and the maneuverability of the vehicle is improved. It will be good.

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

In this embodiment, as shown in FIGS. 10 and 11, the internal gear 15 is engaged with the pinion 56.
7 is fixed to the lower surface of the gear box 34. This internal gear 157 forms an arcuate ring gear whose axis is aligned with the axis of the support shaft 37, and is fixed to the lower surface of the gear box 34 with bolts 158. Therefore, the pinion 56 forms a planetary pinion that rotates around the inner circumference of the internal gear 157.

The above initial settings of the planetary gear mechanisms 56, 157 and the crankshaft 53 are based on the center point (O ₁ ) of the internal gear 157 and the link 51 in the neutral steering state.
The center point (O ₂ ) of the planetary pinion 56 is on the straight line connecting the center point (P) of the joint pin 55.
Do it in a consistent manner.

Also, as shown in Fig. 12, the internal gear 1
It is the same as above except that the reference pitch circle radius of 57 is set to (R ₁ ), and the above-mentioned conditional expressions also hold true with this internal rotation cycloid system.

FIG. 13 shows the trajectory of the center point of the joint pin 55, and FIG. 14 shows the steering characteristics of the rear wheels 12, 12 corresponding to each trajectory. Here, R ₁ = 88.5, and the trajectory and characteristics (A) are R ₂ = 12, R ₃ = 17,
(B) is the case when R ₂ =R ₃ =12, (C) is the case when R ₂ =12 and R ₃ =8, and (D) is the case when R ₂ =R ₃ =8.

It can thus be seen that the same effect as the above-mentioned epicycloid system can be obtained by the internal rotation cycloid system.

By the way, in the above embodiment, the crankshaft 53 and the planetary gear mechanism 56, 57, 157 were configured at the connection part between the lever 41 and the link 51, but the link 51
A similar structure may be applied to the connecting portion between the arm 47 and the arm 47. In that case, a planetary gear mechanism is configured 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 above-mentioned steering device for the front and rear wheels can be applied not only to work vehicles but also to general vehicles such as passenger cars.

(Effects of the invention) As described above, according to the invention, the lever is disposed at the front of the vehicle body and swings in conjunction with the steering wheel, and the tie rod for the left and right rear wheels is connected and supported by the lever which is pivoted at the intermediate part. In a steering device for front and rear wheels, in which one half of the lever or arm and the link are connected by a link, one of the levers or the arms and the link are connected by a crankshaft, and the crankshaft is connected to one of the levers or the arms and the link, respectively. Since the crankshaft is rotatably supported and a planetary gear mechanism is constructed on the shaft portion on the steering input side of the crankshaft and on the vehicle body side, nonlinearization of the rear wheel steering characteristics can be realized with a relatively simple structure.

In particular, a pinion is integrally provided on the shaft on the steering input side of the crankshaft, and an external gear or internal gear with the shaft center as the pivot point of the lever or arm is fixed to the vehicle body in order to mesh with the pinion. Furthermore, since the axis of the shaft on the steering output side of the crankshaft is located inside the pitch circle including the reference pitch circle of the pinion in plan view, the crankshaft that rotates with either the lever or the arm Depending on the rotation of a pinion that is integrally provided and meshes with a fixed external gear or internal gear, the rear wheels can be almost steered in the same way as a normal front-wheel steering vehicle by operating a small steering angle of the steering wheel. By operating the steering wheel at a large steering angle, the rear wheels can be steered by a relatively large amount in the opposite direction to the front wheels, resulting in a small turning radius, which improves maneuverability of the vehicle and makes it easier to maintain straight driving. can be done.

[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 trajectory diagram of an internal rotation cycloid, and FIG. 14 is a rear wheel steering characteristic diagram. In the drawing, 11 is a front wheel, 12 is a rear wheel, 23 is a tie rod for the front wheel, 28 is a tie rod for the rear wheel, and 31 is a tie rod for the rear wheel.
is a handle, 34 is a gearbox, 35 is a pinion, 36 is a sector gear, 37 is a support shaft, 41 is a lever, 46 is a support shaft, 47 is an arm, 51 is a link,
53 is a crankshaft, 54 is a shaft portion on the steering input side, 5
5 is a joint pin which is the shaft part on the steering output side, 56
is a planetary pinion, 57 is an external gear, and 157 is an internal gear.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) 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 pivoted at the intermediate portion, and the arm In a vehicle steering system, one half of the lever or the arm is connected to the lever by a link, and one of the levers or the arm is connected to the link by a crankshaft. and the crankshaft is rotatably supported by one of the levers or the arms and the link, and a pinion is integrally provided on the shaft portion on the steering input side of the crankshaft, and the shaft is configured to mesh with the pinion. An external gear or an internal gear is fixedly provided on the vehicle body side with the center as the pivot point of the lever or arm, and the axis of the shaft portion on the steering output side of the crankshaft is located at the reference pitch of the pinion in plan view. A steering device for front and rear wheels, characterized in that the steering device is located inside the pitch circle including the top of the circle. (2) In a neutral steering state in which the front wheels and the rear wheels are both facing straight ahead, the pinion and
Before and after claim 1 of the utility model registration claim, in which the positional relationship of each axis between the external gear or the internal gear and the shaft portion on the steering output side of the crankshaft is initially set as shown below. Wheel steering device. The axis of the shaft on the steering output side of the crankshaft is aligned with the straight line connecting the axis of the pinion and the external gear. The axis of the pinion is aligned with the straight line connecting the shaft on the steering output side of the crankshaft and the axis of the internal gear.