JPH0725322B2 - Rear wheel steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention steers rear wheels in the same phase as long as the front wheel steering angle is small,
The present invention relates to a rear wheel steering system for a four-wheel steering vehicle that steers the rear wheels in opposite phases when the front wheel steering angle increases.

[Prior Art] In the rear wheel steering system of the vehicle disclosed in JP-A-55-91458, the rear wheels are steered (steered) in the same phase while the front wheel steering angle is small, and the front wheel steering angle is large. Then, in order to steer the rear wheels in the opposite phase, when the pin of the input rod moves in the front-rear direction in association with the front wheel steering, the sliding body having the planar S-shaped cam groove that engages with the pin moves left and right, The rear wheel is steered by the sliding body via the tie rod. In addition, JP-A-58-97
In the one disclosed in Japanese Patent No. 565, a rear wheel is steered via a tie rod by a pin of a crank connected to a planetary gear that operates in a trochoidal curve.

[Problems to be Solved by the Invention] Although the former rear wheel steering device has a simple structure, there is a problem in the wear resistance of the line contact portion between the cam groove of the sliding body and the pin of the input rod, and the line contact The play of the part affects the steering stability of the vehicle. In the latter rear wheel steering system, in order to obtain a large rear wheel steering angle, not only the gear size becomes large and the cost increases, but also there is a disadvantage in terms of an increase in weight and a mounting space for a vehicle.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a small vehicle which can be mounted in a narrow mounting space and which can be arbitrarily set the rear wheel steering angle ratio and which is excellent in wear resistance and reliability. To provide a wheel steering device.

[Means for Solving the Problem] In order to achieve the above object, the structure of the present invention is configured such that a guide member having a rectangular cross section is connected to a rear end portion of an input shaft in a front-rear direction which is rotated by a handle operation. A rear end of the output shaft is supported on the vehicle body by a spherical bearing on the rear extension line, and an arcuate sliding member penetrating the guide member is coupled to the front end of the output shaft. A toothless bevel gear is fixed to the vehicle body concentrically with the input shaft, a partial gear centering on the spherical bearing is formed on the sliding member, and a pinion meshed with the partial gear is attached to one end of the shaft supported on the side wall of the guide member. A bevel gear that meshes with a pair of front and rear tooth-missing bevel gears is connected to the other end of the shaft, and a mechanism is provided for converting a conical motion with the spherical bearing of the output shaft as a fulcrum into a lateral movement of the rear wheel steering tie rod. The bevel gear rotates as the input shaft rotates from its neutral position. It meshes with the toothless bevel gear on one side to draw the partial gear into the guide member,
When the output shaft is coaxial with the input shaft, the region where the rear wheels are steered in the same phase as the front wheels is switched to the region where the rear wheels are steered in the opposite phase to the front wheels.

[Operation] For example, when the handle is turned to the right from the neutral position, the guide member rotates together with the input shaft, the bevel gear supported by the guide member meshes with one of the pair of toothless bevel gears, and the partial gear is driven by the pinion. Is driven. As a result, the cone angle of the conical motion of the output shaft that supports the partial gear gradually decreases, the rear-wheel steering tie rod that engages with the intermediate portion of the output shaft moves to the right, and the rear wheel becomes in phase with the front wheel. Steer.

When the output shaft is coaxially aligned with the input shaft, the rear wheels return to the straight-ahead position, and the region where the rear wheels are steered in the same phase as the front wheels is switched to the region where the rear wheels are steered in the opposite phase to the front wheels.

When the steering wheel is further turned to the right, the cone angle of the conical motion of the output shaft increases, and the rear-wheel steering tie rod moves leftward to steer the rear wheels in the opposite phase to the front wheels.

Embodiment of the Invention FIG. 3 is a plan view showing a schematic configuration of a four-wheel steering vehicle equipped with a rear wheel steering device. Each knuckle arm 6 that supports the left and right front wheels 4 is rotatably supported on the vehicle body by a vertical support shaft 6a, and is connected to both ends of the tie rod 8 by pins 5. Tyrod 8 equipped with a rack,
Inside the base frame that houses the steering gear mechanism 7, it is meshed with the pinion of the steering shaft 3 that is operated by the handle 2.

The movement of the tie rod 8 in the left-right direction has a pinion 9 that meshes with the rack of the tie rod 8 and extends rearward.
The rotation of 10 is transmitted to the rear wheel steering device 12. An output shaft 68, which is an output member of the rear wheel steering device 12, is engaged with the tie rod 23. Both ends of the tie rod 23 are pinned to the knuckle arm 25 and the pin.
Connected by 24. Natsukuru arm that supports the rear wheel 27
25 is rotatably supported on the vehicle body by a vertical support shaft 25a.

As shown in FIGS. 1 and 2, the rear wheel steering device 12 includes a pair of stationary tooth-chipped bevel gears 53, 5 on a bracket 51, 51 a fixed to a vehicle body 52.
Equipped with 8. The bevel gear 53 with missing teeth has a central angle θ (180 ° or less).
There are teeth in the other part, and there are no teeth in the other parts. Specifically, in the neutral position shown in FIG. 1, the tooth-chipped bevel gear 53 has teeth on the upper half and no teeth on the lower half. On the contrary, the bevel gear without teeth 58
Has no teeth on the upper half and has teeth on the lower half. Therefore, the bevel gear 65 selectively meshes with the toothless bevel gears 53, 58.
When it revolves upward from the neutral position shown in FIG. 1, it meshes with the toothless bevel gear 53, and when it revolves downward, it meshes with the toothless bevel gear 58.

The input shaft 10 penetrates through the shaft centers of the bracket 51 and the bevel gear 53 having no teeth, and a guide member 54 having a rectangular cross section is coupled between the pair of bevel gears 53, 58 having no tooth. Arc-shaped opening formed in the guide member 54
A sliding member 56 having an arc-shaped partial gear 56a penetrates through 55. A pinion 65a meshing with the partial gear 56a is coupled to an inner end of a shaft 66 supported on a side wall of the guide member 54. A bevel gear 65 is coupled to the outer end of the shaft 66.

The output shaft 68 has a front end to which a sliding member 56 is coupled via an arm 57, and a spherical seat 62, which constitutes a spherical bearing at the rear end, is engaged with a sphere 63 of the vehicle body 52. The intermediate portion of the output shaft 68 is connected to the tie rod 23 by the conversion mechanism A. That is, an opening 59 having a rectangular cross section that extends in the front-rear direction is integrally formed in the tie rod 23, and a spherical seat 60 having a spherical surface 67 formed of two halves is slidable in a vertical guide groove 69 formed in the opening 59. Supported. A flat partial sphere 61 supported by the output shaft 68 slidably in the axial direction is engaged with the spherical seat 60.

Next, the operation of the rear wheel steering system according to the present invention will be described. When the front wheels 4 are in a straight traveling state, the bevel gear 65 is in the neutral position shown in FIG. 1, that is, on the right side of the longitudinal axis 50, and partially (slightly) meshes with the teeth of the tooth-chipped bevel gears 53, 58. It fits. The center axis of the output shaft 68 is a plane axis in the front-back direction.
Consistent with 50, the arm 57 is above the longitudinal axis 50.

Turning the handle 2 to the right in FIG. 3, the tie rod 8
Moves to the left, the knuckle arm 6 rotates clockwise around the support shaft 6a, and the front wheel 4 is deflected to the right. When the guide member 54 is rotated together with the input shaft 10 in the direction of the arrow in FIG. 1 along with the leftward movement of the tie rod 8, the bevel gear 65 meshes only with the bevel gear 58 with no teeth, and together with the bevel gear 65. On pinion
65a is rotated in the direction of the arrow, the partial gear 56a is fed inward of the guide member 54 (to the back side of the paper surface of FIG. 1), and the cone angle α (FIG. 2) of the output shaft 68 is gradually reduced. At the same time, output shaft
The arm 57 and the output shaft 68 tilt to the right of the longitudinal axis 50 along with the conical movement of the sphere 63 of the 68. Therefore, the tie rod 23 moves to the right, and the knuckle arm 25 rotates clockwise about the support shaft 25a in FIG.
Is deflected to the right (in phase with the front wheels 4). When the input shaft 10 rotates 90 ° from the neutral position (the state shown in FIG. 2), the rear wheels 27 reach the maximum steering angle in the same phase. At this time, the position of the bevel gear 65 is below the toothless bevel gears 53 and 58.

When the input shaft 10 further rotates in the same direction, the partial gear 56a is continuously fed inward of the guide member 54, the cone angle α of the output shaft 68 gradually decreases, and when the input shaft 10 rotates 180 ° from the neutral position, The cone angle α becomes 0, the central axis of the output shaft 68 coincides with the longitudinal axis 50, and the arm 57 is positioned in the longitudinal axis.
Below 50. While the input shaft 10 rotates from 90 ° to 180 °, the tie rod 23 moves leftward and returns to the neutral position.

When the input shaft 10 further rotates in the same direction, the partial gear 56a is continuously fed to the guide member 54, and the cone angle α of the output shaft 68
Will gradually increase. The arm 57 and the output shaft 68 tilt to the left side of the longitudinal axis 50 along with the conical movement of the output shaft 68 around the sphere 63. Therefore, Tyrod 23 moved to the left,
The knuckle arm 25 rotates counterclockwise about the support shaft 25a in FIG. 3, and the rear wheel 27 is deflected to the left (in the opposite phase to the front wheel 4).

When the handle 2 is cut from the neutral position to the left, the bevel gear 65
Operates in the same way by meshing only with the toothless bevel gear 53. When the steering wheel 2 has a small cutting angle, the front wheel 4 and the rear wheel 27 are both deflected to the left, and when the steering wheel 2 has a large cutting angle, Wheel 27 is deflected to the right.

The amount of movement of the tie rod 23 with respect to the rotation angle of the input shaft 10 (corresponding to the steering angle of the front wheels 4), that is, the steering angle of the rear wheels 27 exhibits the characteristics shown in FIG. The characteristics of the rear wheel rudder angle are set arbitrarily by changing the gear ratio between the bevel gear 65 and the pinion 65a, specifically by simply replacing the sliding member 56 of the pinion 65a, as shown by the broken line in FIG. can do.

[Advantages of the Invention] As described above, according to the present invention, a guide member having a rectangular cross section is coupled to a rear end of an input shaft in the front-rear direction rotated by a handle operation, and a spherical bearing is provided on a rear extension line of the input shaft by an output shaft. The rear end is supported by the vehicle body, an arcuate sliding member penetrating the guide member is coupled to the front end of the output shaft, and a pair of front and rear tooth-chipped bevel gears facing each other with the guide member interposed therebetween are concentric with the input shaft. A partial gear centering on the spherical bearing is formed on the sliding member, and a pinion meshing with the partial gear is attached to one end of a shaft supported on the side wall of the guide member, and a pair of front and rear pairs is attached to the other end of the shaft. Since the bevel gears meshing with the toothless bevel gears are respectively coupled to each other, a mechanism for converting the conical movement with the spherical bearing of the output shaft as a fulcrum into the lateral movement of the rear wheel steering tie rod is used. When the pinion is rotated by the input shaft, the pinion The output shaft that connects the partial gears that mesh with is tilted, the rear wheel steering tie rod moves left and right, and the rear wheels are steered.

The rear wheel rudder angle changes to the same phase when the front wheel rudder angle is small, and becomes the opposite phase when the front wheel rudder angle becomes large, so that stable steering without vehicle shake when changing lanes at high speed is obtained, and low speed You can get a good maneuverability while turning around on a narrow road or entering a garage.

According to the present invention, for example, by changing the pinion that meshes with the partial gear or changing the inclination of the output shaft at the neutral position, the maximum steering angle of the rear wheel in the same phase and the maximum steering angle of the rear wheel in the opposite phase can be obtained. The ratio to the rudder angle can be set freely, the components transmitting the steering power are composed of a gear mechanism, and there is no rattling, so that it has wear resistance and operational reliability is improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a neutral position (straight running state) of a rear wheel steering system for a vehicle according to the present invention, and FIG. 2 is a plan view showing a right-turned state (same phase as front wheels) of the rear wheel steering system. FIG. 3 is a plan view showing a schematic configuration of a vehicle equipped with the rear wheel steering device,
FIG. 4 is a characteristic diagram of the rear wheel steering system. A: Conversion mechanism, 23: Ti rod, 10: Input shaft, 52: Body, 53,
58: Partial bevel gear, 54: Guide member, 56: Sliding member, 56a: Partial gear, 57: Arm, 65: Bevel gear, 65a: Pinion, 66: Shaft, 68: Output shaft

Claims (2)

[Claims] 1. A guide member having a rectangular cross section is coupled to a rear end portion of an input shaft in a front-rear direction which is rotated by a handle operation, and a rear end of the output shaft is supported on a vehicle body by a spherical bearing on a rear extension line of the input shaft. , A front-rear direction in which an arcuate sliding member penetrating the guide member is coupled to the front end of the output shaft and facing each other with the guide member interposed therebetween 1
A pair of toothless bevel gears is fixed to the vehicle body concentrically with the input shaft, a partial gear centering on the spherical bearing is formed on the sliding member, and a pinion meshed with the partial gear at one end of the shaft supported on the side wall of the guide member. Is connected to the other end of the shaft with a bevel gear that meshes with a pair of front and rear bevel gears, and a conical motion with the spherical bearing of the output shaft as a fulcrum is converted into a lateral movement of the rear wheel steering tie rod. The bevel gear is engaged with one of the toothless bevel gears as the input shaft rotates from the neutral position and pulls the partial gear into the guide member.When the output shaft is aligned with the input shaft, the rear wheel is the same as the front wheel. A rear-wheel steering system for a vehicle, wherein the rear-wheel steering device switches a rear-wheel steering area to a front-wheel steering area in a phase opposite to a front-wheel steering area. 2. A mechanism for converting a conical motion of the output shaft into a left-right movement of a rear-wheel steering tie rod is provided with an opening having a rectangular cross section extending in the front-rear direction at an intermediate portion of the rear-wheel steering tie rod. The rear wheel steering apparatus for a vehicle according to claim (1), wherein a partial spherical body formed in an intermediate portion of the output shaft is supported by a spherical bearing that is vertically movable along a groove.