JP2011093404A - Steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering system changing the rate of variation of a steering amount of a single front wheel 12F with respect to variation of an operation amount of a steering wheel 40. <P>SOLUTION: The steering system 10 includes an operation device 20 having a main shaft 52, a telescopic suspension device 24 steering the front wheel according to the rotation of a stem 68, and a rotation transmission device 26 having an operation side pulley 70 rotating integrally with the main shaft, a steered side pulley 72 rotating integrally with the stem, and a loop-shape belt 74 wound around outer peripheries of the pulleys and transmitting the rotation of the main shaft as the rotation of the stem, and the operation side pulley and the steered side pulley are manufactured so as to have cross-sectional shapes respectively allowing a rotation transmission ratio that is a ratio of a rotational angular velocity of the operation side pulley to a rotational angular velocity of the steered side pulley changes accompanying a rotation phase of the operation side pulley. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a steering system in a vehicle including a single front wheel disposed in a front portion of a vehicle and a left wheel and a right wheel respectively disposed on the left and right behind the front wheel.

  Conventionally, a vehicle including a single front wheel that is disposed at the front portion of the vehicle and serves as a steered wheel, and a left wheel and a right wheel that are respectively disposed on the left and right in the vehicle width direction behind the front wheel of the vehicle, that is, There is a vehicle that runs on three wheels. Further, in recent years, as described in Patent Document 1 below, in addition to the front wheels and the left and right wheels, a vehicle in which a single rear wheel is arranged at the rear portion of the vehicle, that is, four wheels are provided. Vehicles arranged in a diamond shape are also being studied.

  On the other hand, in a conventional vehicle having four front wheels, each of which has four wheels arranged at the left and right sides of the front and rear portions of the vehicle, that is, at the four corners of the vehicle, to steer the two front wheels that are steered wheels In addition, a rack and pinion type steering system as described in Patent Document 2 below is generally used. Further, in a recent steering system, as described in Patent Document 2 below, the ratio of the change in the wheel turning amount to the change in the operation amount of the operation member according to the operation amount of the operation member by the driver There are also things that fluctuate. If such a steering system is employed, for example, when the operation amount is relatively small, the ratio of the change in the wheel turning amount to the change in a certain operation amount is reduced to improve the straight running stability of the vehicle. On the other hand, when the operation amount is relatively large, it is possible to easily change the direction of the vehicle by increasing the ratio of the change in the wheel turning amount with respect to the same change in the operation amount.

Chinese patent advertisement 1304237 JP 2002-31941 A

  Even in the case of a vehicle having a single front wheel as a steered wheel, it is possible to adopt a rack and pinion type steering system as in a conventional vehicle, but a rack and pinion type steering system is There is a problem that processing for manufacturing a gear mechanism such as a pinion is expensive, or a heavy metal member is used, resulting in an increase in weight. In addition, the steering system described in Patent Document 2 has a complicated structure because it includes a drive source such as a motor in order to change the rate of change in the amount of steering of the wheel with respect to change in the amount of operation of the operation member. This is an expensive steering system. The present invention has been made in view of such circumstances, and an object thereof is to improve the practicality of a steering system that steers a single front wheel.

Means and effects for solving the problem

  A steering system of the present invention is mounted on a vehicle including a single front wheel disposed at a front portion, and a left wheel and a right wheel respectively disposed on the left and right behind the front wheel, for turning the front wheel. A steering system comprising: (A) an operating member operated by a driver; an operating device having an output shaft that rotates according to the operation of the operating member; and (B) an input shaft having the input shaft. (C) a first rotating body attached to the output shaft and rotating integrally with the output shaft, and attached to the input shaft and integrated with the input shaft Rotation of the input shaft having a second rotating body that rotates automatically, and a loop-shaped rotation transmission member that is wound around both the outer periphery of the first rotating body and the outer periphery of the second rotating body. A rotation transmission device for transmitting the rotation as the rotation of the output shaft, and a first rotation And the second rotator each have a cross-sectional shape in which a rotation transmission ratio, which is a ratio of the rotation angular velocity of the first rotator to the rotation angular velocity of the second rotator, varies according to the rotation phase of the first rotator. It is prepared as follows.

  According to this steering system, the first rotating body attached to the operating device, the second rotating body attached to the steering device, and the rotation transmission member wound around these rotating bodies are simple and lightweight. The front wheels can be steered by the structure steering device. In addition, since the first rotating body and the second rotating body are prepared so that the rotation transmission ratio fluctuates according to the rotation phase of the first rotating body, the operation member is operated according to the operation amount of the operation member. It is possible to vary the ratio of the change in the turning amount of the wheel with respect to the change in the amount.

  The cross-sectional shapes of the first rotating body and the second rotating body in the rotation transmission device are not particularly limited as long as the rotation transmission ratio can be changed according to the rotation phase of the first rotating body. . For example, one or both of the first rotating body and the second rotating body can be rotated by adjusting the distance from the position to the center of rotation according to the circumferential position on the outer periphery of the rotating body. The transmission ratio varies according to the rotational phase of the first rotating body.

  For the first rotating body, the second rotating body, and the rotation transmitting member, pulleys and belts, sprockets and chains, rollers and wires, which will be described later, or other members can be used. It can also be used.

  In addition, since the rotation transmission ratio with respect to the rotation phase of the first rotating body can be changed by changing the cross-sectional shape of these rotating bodies, the front wheel with respect to the operation amount of the operating member can be changed by changing the cross-sectional shape of these rotating bodies. The amount of steering can be changed. Further, by providing a difference in the size in the radial direction between the first rotator and the second rotator, for example, when the first rotator rotates halfway, the second rotator is rotated 1/4. A reduction mechanism can also be provided in the rotation transmission device.

  One of the first rotating body and the second rotating body may have a circular cross section, and the other cross sectional shape may be an ellipse or an oval. For example, when the cross-sectional shape of the first rotating body is a circular shape and the cross-sectional shape of the second rotating body is an elliptical shape, the first rotating body is positioned according to the circumferential position on its outer periphery. The distance from the center of rotation to the center of rotation is constant, but the distance from the position to the center of rotation of the second rotating body varies depending on the position in the circumferential direction on its outer periphery. Therefore, if the distance that the rotation transmitting member circulates around the outer periphery of the first rotating body and the second rotating body, that is, the distance that one point on the rotation transmitting member moves by the rotation of the rotation transmitting member is defined as the circulation amount. The rotation angle of the first rotating body is constant regardless of the rotation phase of the first rotating body with respect to a certain amount of rotation of the rotation transmitting member, but the rotating angle of the second rotating body is the same as that of the second rotating body. It fluctuates according to the rotation phase. Therefore, the rotation transmission ratio can be varied according to the rotation phase of the first rotating body.

  The rotation transmission device is preferably configured such that the rotation transmission ratio is the smallest when the front wheels are positioned at the neutral position, and the rotation transmission ratio increases as the amount of steering of the front wheels increases. When the position of the front wheel when the vehicle is in a straight traveling state is set to the neutral position, when the front wheel is positioned at the neutral position, the rotation transmission ratio is minimized, and the operation amount of the operation member is relatively small. The ratio of the change in the amount of steering of the wheel with respect to a change in a certain operation amount can be reduced to improve the straight running stability of the vehicle. On the other hand, if the rotation transmission ratio is increased as the turning amount of the front wheels increases, when the operation amount is relatively large, the ratio of the change in the wheel turning amount to the change in a certain operation amount is increased. Thus, the direction of the vehicle can be easily changed.

  Each of the first rotating body and the second rotating body may be a pulley, and the rotation transmission member may be a belt. By using a pulley and a belt, a steering system that is easy to manufacture and inexpensive can be obtained.

  The rotation transmission device may include a tension applying mechanism that applies tension to the rotation transmission member in order to prevent the rotation transmission member from loosening. The tension applying mechanism may include, for example, a roller that is pressed against the rotation transmission member to generate a tensile stress on the rotation transmission member, a compression spring that presses the roller against the rotation transmission member, and the like. By configuring the rotation transmitting device to have a tension applying mechanism, it is possible to prevent slippage between the rotation transmitting member and each rotating body.

  This steering system is mounted on a vehicle in which the front wheel is located in the center in the vehicle width direction, and the seat on which the driver is seated is arranged in an eccentric position in the vehicle width direction. It is suitable for a vehicle that is located at a position shifted with respect to the input shaft of the steering device in the width direction according to the position of the seat. That is, since the rotation of the output shaft can be transmitted to the input shaft via the rotation transmitting member, the front wheels can be steered by a simple steering system.

1 is a schematic diagram showing an overall configuration of a vehicle equipped with a steering system that is an embodiment of the present invention. It is a perspective view which shows the steering system of an Example. It is a schematic diagram which shows the rotation transmission apparatus of the steering system of an Example. It is a graph which shows the rotation transmission ratio with respect to the rotation phase of the 1st rotary body in the steering system of an Example.

  Hereinafter, as a mode for carrying out the present invention, a steering system of an embodiment will be described in detail with reference to the drawings. Note that the steering system of the present invention is not limited to the following embodiments, and can be in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

≪Steering system configuration≫
FIG. 1 schematically shows a vehicle on which the steering system 10 of the embodiment is mounted. This vehicle has four wheels 12 arranged in a diamond shape. Specifically, a single front wheel 12F disposed at the front of the vehicle and in the center in the vehicle width direction, a left wheel 12M _L and a right wheel 12M _R respectively disposed on the left and right of the vehicle behind the front wheel 12F, And a single rear wheel 12R disposed at the center in the vehicle width direction.

Left wheel 12M _L and the right wheel 12M _R of the four wheels 12 are drive wheels in this vehicle. Each of the left wheel 12M _L and the right wheel 12M _R is provided with a driving device 14 having a motor as a driving source. Detailed description is omitted, the drive unit 14, the motor force according to the operation of the accelerator device 16 mainly composed of an accelerator pedal, to drive the left wheel 12M _L and a right wheel 12M _R. Each of the four wheels 12 is provided with a brake device so that each wheel 12 can be braked.

  The front wheel 12F is a steered wheel in the vehicle, and is steered by the steering system 10 shown in FIG. The rear wheel 12R is a caster that can rotate with respect to the vehicle body, and can freely rotate with respect to the vehicle body in accordance with the turning of the vehicle.

  The steering system 10 is steered so that the front wheel 12F is steered according to the operation received in the operation device 30, the steering device 32 that steers the front wheel 12F, and the operation device 30 that receives the operation. And a rotation transmission device 34 for operating the device 32.

  The operating device 30 includes a steering wheel 40 that is an operating member operated by a driver, a steering shaft 42 to which the steering wheel 40 is connected to one end thereof, and a steering shaft 42 that is rotatably held and fixed to the vehicle body. And a steering tube 44 formed. The other end of the steering shaft 42 is connected to an intermediate shaft 48 through a universal joint 46. The intermediate shaft 48 is further connected to one end of the output shaft 52 via a universal joint 50. The output shaft 52 is rotatably held by the vehicle body at the other end thereof. Since the seat on which the driver is seated is located on the right side of the vehicle, the operating device 30 is also located on the right side of the vehicle.

  Further, an assisting device 58 for assisting a steering force that is a force for steering the front wheels 12F is attached to the front side of the steering tube 44 in the vehicle. The assisting device 58 has a drive source, and it is possible to assist the steering force by applying rotational torque corresponding to the operation torque of the steering wheel 40 to the steering shaft 42.

  The steered device 32 has two wheel holding members 62 that hold the axle provided on the front wheel 12F at one end from both sides, and an oval crown 66 that holds the other end of each of the two wheel holding members 62. And an input shaft 68 having one end fixed to the central portion of the crown 66. The input shaft 68 is rotatably held by the vehicle body at the other end thereof. Although not described in detail, each of the two wheel holding members 62 includes a compression coil spring and an oil damper, and the steering device 32 elastically supports the front wheel 12F with respect to the vehicle body. It also has a function as a suspension device.

  In the steering device 32, the input shaft 68 is located at the center in the vehicle width direction together with the front wheels 12F. Further, in the operating device 30, the output shaft 52 is located on the right side in the vehicle width direction together with the steering wheel 40. That is, in the present steering system 10, the output shaft 52 is located at a position shifted in the vehicle width direction with respect to the input shaft 68.

  The rotation transmission device 34 includes an operation side pulley 70 attached to the output shaft 52, a steered side pulley 72 attached to the input shaft 68, an outer peripheral portion of the operation side pulley 70, and an outer peripheral portion of the steered side pulley 72. And a loop-shaped belt 74 wound around both. The operation-side pulley 70 can rotate about the rotation axis of the output shaft 52 integrally with the output shaft 52. The cross-sectional shape orthogonal to the rotation axis of the operation side pulley 70 is a circle. The steered pulley 72 is rotatable around the rotation axis of the input shaft 68 integrally with the input shaft 68. In addition, the cross-sectional shape orthogonal to the rotation axis of the turning pulley 72 is an ellipse, and when the front wheel 12F is in a neutral position that is not being steered, its long axis is the longitudinal direction of the vehicle. The steered side pulley 72 is fixed to the input shaft 68 so as to face.

  The operation-side pulley 70 and the steered-side pulley 72 are arranged such that their rotation axes are parallel to each other. That is, in the steering system 10, the output shaft 52 and the input shaft 68 are arranged so that their rotational axes are parallel to each other. Further, the operation side pulley 70 and the steered side pulley 72 are arranged on a plane perpendicular to the respective rotation axes.

  In the steering system 10 configured as described above, the output shaft 52 is an output shaft in the operation device 30, and the input shaft 68 is an input shaft in the steering device 32. In the rotation transmission device 34, the operation-side pulley 70, the steered-side pulley 72, and the belt 74 are a first rotating body, a second rotating body, and a rotation transmitting member, respectively. Therefore, when the steering wheel 40 is operated, the operation side pulley 70 is rotated together with the output shaft 52, and the belt 74 is caused to go around the outer peripheral portions of the operation side pulley 70 and the steered side pulley 72. The steered pulley 72 is rotated together with the input shaft 68 by the rotation of the belt 74. That is, the rotation transmission device 34 can transmit the rotation of the output shaft 52 as the rotation of the input shaft 68. Therefore, when the steering wheel 40 is operated, the steering device 32 is rotated and the front wheels 12F are steered. Incidentally, when the front wheel 12F is in the neutral position and the operation side pulley 70 is rotated by 90 °, the rotation transmission device 34 rotates the steered side pulley 72 by 90 ° to direct the front wheel 12F to the side. It is configured to let you.

  As shown in FIG. 3, the steering system 10 includes a tensioner 80 on a plane on which the operation side pulley 70 and the steered side pulley 72 are arranged. The tensioner 80 roughly includes a roller 82 that contacts the belt 74, a holding member 84 that rotatably holds the roller 82, and one end portion of the tensioner 80 that is fixed to the holding member 84 and the other end portion that is fixed to the vehicle body. And a compression coil spring 86. The tensioner 80 can press the roller 82 against the belt 74 by the compression reaction force of the compression coil spring 86, and is a tension applying mechanism that can apply tension to the belt 74. Therefore, the slack of the belt 74 is prevented, and slippage between the belt 74 and the operation side pulley 70 and the steered side pulley 72 can be prevented.

≪Operation of rotation transmission device≫
3A to 3C show a state where the operation side pulley 70 is rotated by the operation of the steering wheel 40 and the steered side pulley 72 is rotated via the belt 74. FIG. 3A shows a state where the front wheels 12F are in the neutral position, that is, the positions where the front wheels 12F are not steered. When the steering wheel 40 is operated and the front wheel 12F is steered from the neutral position, the amount of rotation of the operation side pulley 70 and the steered side pulley 72 is set to the operation side rotational phase θ _S and the steered side, respectively. This is expressed as a rotational phase θ _T. Incidentally, FIG. 3 is a view of the rotation transmission device 26 as viewed from below, and shows the operation-side pulley 70 and the steering-side pulley 72 when the steering wheel 40 is operated so as to steer the front wheel 12F in the right direction. Shows rotation.

Further, the operation-side rotation phase θ _S is equal to the amount by which the steering wheel 40 is rotated when the front wheels 12F are steered from the neutral position. That is, the operation side rotation phase θ _S also indicates the operation amount of the steering wheel 40. Further, the turning-side rotation phase θ _T is equal to the amount by which the front wheels 12F are rotated when the front wheels 12F are steered from the neutral position. That is, the turning-side rotation phase θ _T also indicates the turning amount of the front wheels 12F. Since the operation device 30 is provided with a stopper for restricting the rotation of the steering wheel 40, the operation device 30 is operated with the operation-side rotation phase θ _S exceeding 90 ° on both the left and right sides. Absent.

3 (a) to 3 (c) will be described in detail. In FIG. 3 (a), the front wheel 12F is in the neutral position, and the operation side rotation phase θ _S and the steered side rotation phase θ _T are each 0 °. It shows the state. In the state of FIG. 3B, the operation side pulley 70 is rotated from the state of FIG. 3A until the operation side rotation angle dθ _S1 is 45 °, that is, the operation side rotation phase θ _S is 45 °. The state is shown. The operation side pulley 70 thus rotated rotates the belt 74 by a distance L _{1 at} the outer peripheral portions of the operation side pulley 70 and the steered side pulley 72. In accordance with this distance L ₁ , the steered pulley 72 is rotated by the steered side rotation angle dθ _T1 . In this case, the turning-side rotation angle dθ _T1 , that is, the turning-side rotation phase θ _T is smaller than 45 °. 3C, the operation-side pulley 70 is rotated from the state of FIG. 3B until the operation-side rotation angle dθ _S2 is 45 °, that is, the operation-side rotation phase θ _S is 90 °. The state is shown. The operation side pulley 70 rotated in this way causes the belt 74 to circulate by a distance L _{2 at} the outer peripheral portions of the operation side pulley and the steered side pulley. The steered side pulley 72 is rotated by the steered side rotation angle dθ _T2 according to the distance L ₂ . In this case, the turning-side rotation angle dθ _T1 is larger than 45 °, and the turning-side rotation phase θ _T in this state, that is, the sum of the turning-side rotation angles dθ _T1 and dθ _T2 is 90 °. Become.

Since the operation-side pulley 70 has a circular cross-sectional shape, the operation-side pulley 70 is rotated from the state shown in FIGS. 3A to 3B and the state shown in FIGS. 3B to 3C. The distance L ₁ is equal to the distance L ₂ when the operation-side pulley 70 is rotated. That is, the operation-side pulley 70 is related to the operation-side rotation phase θ _S if the amount of rotation of the belt 74, that is, the distance that the belt 74 circulates around the outer periphery of the operation-side pulley 70 and the steered-side pulley 72 is constant. In other words, the operation-side rotation angle dθ _S is constant. On the other hand, the steering-side rotation angle dθ _{T that} is the rotation angle of the steering-side pulley 72 is changed from the state shown in FIGS. 3A to 3B because the cross-sectional shape of the steering-side pulley 72 is elliptical. The case where the operation side pulley 70 is rotated is different from the case where the operation side pulley 70 is rotated from the state shown in FIG. That is, the turning-side pulley 72 varies the turning-side rotation angle dθ _T in accordance with the turning-side rotation phase θ _T even if the turning amount is constant. Therefore, the rotation transmission device 34 can change the rotation transmission ratio according to the operation side rotation phase θ _S.

FIG. 4 shows a rotation transmission ratio dθ _T / dt which is a ratio of the rotational angular velocity dθ _S / dt of the operating pulley 70 and the rotational angular velocity dθ _T / dt of the steered pulley 72 with respect to the change of the operating rotational phase θ _S. 6 is a graph showing fluctuations in dθ _S. In other words, the rotation transmission ratio dθ _T / dθ _S is a value indicating the rate of change of the turning-side rotation phase θ _T with respect to the operation-side rotation phase θ _S. That is, when the rotation transmission ratio dθ _T / dθ _S is larger than 1.0, when the operation side pulley 70 is rotated by a certain operation side rotation angle dθ _S1 , the steering side rotation angle dθ _T1 associated therewith becomes the operation side rotation. It becomes larger than the angle dθ _S1 . On the other hand, when the rotation transmission ratio dθ _T / dθ _S is smaller than 1.0, even if the operation-side pulley 70 rotates by a certain operation-side rotation angle dθ _S2 , the steered-side rotation angle dθ _T2 associated therewith is rotated. It becomes smaller than the angle dθ _S2 . Incidentally, when the ratio of the length of the major axis to the minor axis of the steered pulley 72 is changed, the fluctuation of the rotation transmission ratio dθ _T / dθ _S may be different from the fluctuation shown in FIG. it can.

Therefore, the steering system 10 reduces the rotation transmission ratio dθ _T / dθ _{S and} reduces the straight running stability of the vehicle when the operation amount is relatively small, such as when the vehicle travels straight or travels along a gentle curve. On the other hand, when the operation amount is relatively large, such as when the vehicle makes a U-turn, the rotation transmission ratio dθ _T / dθ _S is increased, and the vehicle can be easily turned. Thus, according to the present steering system 10, since the cross-sectional shape of the operation-side pulley 70 is circular and the cross-sectional shape of the steered-side pulley 72 is elliptical, the operation-side rotation phase θ _S Accordingly, the rotation transmission ratio dθ _T / dθ _S can be varied. That is, according to the operation amount of the steering wheel 40, the ratio of the change in the turning amount of the front wheel 12F with respect to the change in the operation amount of the steering wheel 40 can be changed.

  By the way, this steering system 10 can also be made to have the same steering system by making the cross-sectional shape of the steered side pulley an oval. In other words, when the front wheels are in the neutral position, if the steered pulley, which is an oval, is fixed to the input shaft so that it faces the front-rear direction of the vehicle, the rotation transmission ratio varies according to the operation-side rotation phase. Can be made. Therefore, the ratio of the change in the steering amount of the front wheel to the change in the operation amount of the steering wheel can be varied according to the operation amount of the steering wheel.

  Further, the cross-sectional shapes of the operation side pulley and the steered side pulley are not particularly limited as long as the rotation transmission ratio can be changed according to the rotation phase of the operation side pulley. Prepare one or both of the operation-side pulley and the steered-side pulley so that the distance from the position to the center of rotation differs according to the position in the circumferential direction on its outer circumference, such as an oval or oval shape. Thus, the rotation transmission ratio is changed according to the rotation phase of the operation side pulley.

  Thus, according to the present steering system 10, the operation side pulley 70 attached to the operation device 30, the steering side pulley 72 attached to the steering device, and the belt 74 wound around these pulleys. The single front wheel 12F can be steered by the simple rotation transmission device 34 constituted by Further, the present steering system 10 uses pulleys and belts without using expensive and heavy members such as racks and pinions, so that it is easy to manufacture and is inexpensive and uses metal members. Because of its small volume, it is a light steering system. Further, the present steering system 10 is a vehicle in which the output shaft 52 of the operation device 30 is shifted with respect to the input shaft 68 of the steering device 32 that steers the single front wheel 12F in the vehicle width direction. Is preferred. That is, since the rotation of the output shaft 52 can be transmitted to the input shaft 68 via the belt 74, the front wheels 12F can be steered by a simple steering system.

DESCRIPTION OF SYMBOLS 10: Steering system 12: Wheel 30: Operation apparatus 32: Steering apparatus 34: Rotation transmission apparatus 40: Steering wheel (operation member) 52: Output shaft (output shaft) 68: Input shaft (input shaft) 70: Operation side pulley (First rotating body) 72: Steering side pulley (second rotating body) 74: Belt (rotation transmission member) 80: Tensioner (tension applying mechanism) dθ _S / dt: Rotational angular velocity of the operation side pulley 70 dθ _T / dt : Rotational angular velocity of the steered pulley 72 dθ _T / dθ _S : rotation transmission ratio

Claims (6)

A steering system for turning a front wheel mounted on a vehicle having a single front wheel disposed in a front portion and a left wheel and a right wheel respectively disposed on the left and right behind the front wheel,
An operating device having an operating member operated by a driver and an output shaft that rotates in accordance with the operation of the operating member;
A steering device that has an input shaft and steers the front wheel according to the rotation of the input shaft;
A first rotating body attached to the output shaft and rotating integrally with the output shaft; a second rotating body attached to the input shaft and rotating integrally with the input shaft; and A rotation transmission device having a loop-shaped rotation transmission member wound around both the outer peripheral portion and the outer peripheral portion of the second rotating body, and transmitting the rotation of the input shaft as the rotation of the output shaft; Prepared,
Each of the first rotating body and the second rotating body has a rotation transmission ratio, which is a ratio of the rotating angular velocity of the first rotating body to the rotating angular velocity of the second rotating body, according to the rotation phase of the first rotating body. The steering system is prepared so as to have a cross-sectional shape that fluctuates.   The steering system according to claim 1, wherein one of the first rotating body and the second rotating body has a circular cross-sectional shape, and the other cross-sectional shape is an ellipse or an oval.   The rotation transmission device is configured such that the rotation transmission ratio is the smallest when the front wheels are located in a neutral position, and the rotation transmission ratio increases as the amount of steering of the front wheels increases. The steering system according to claim 1 or 2.   The steering system according to any one of claims 1 to 3, wherein each of the first rotating body and the second rotating body is a pulley, and the rotation transmission member is a belt.   The steering system according to any one of claims 1 to 4, wherein the rotation transmission device includes a tension applying mechanism that applies tension to the rotation transmission member to prevent the rotation transmission member from slackening. The steering system
The front wheel is located in the center in the vehicle width direction, and the seat on which the driver is seated is mounted on the vehicle disposed in an eccentric position in the vehicle width direction,
The said output shaft of the said operating device is located in the position shifted with respect to the said input shaft of the said steering device according to the position of the said sheet | seat in the vehicle width direction. Steering system described in one.

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