JP2012236563A - Steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical steering system that matches conditions of a vehicle used or features of the vehicle.SOLUTION: The steering system includes: an operation device 16 having a steering wheel 26 which is operated by a driver; a front-wheel steering device 18 for holding a front wheel 14F in a rotatable manner and steering the front wheel; and a transmission device 20 for achieving steering of the front wheel by the front-wheel steering device in response to an operation of the steering wheel. When an operation amount of the steering wheel from a state of vehicle traveling straight is between a first operation amount and a second operation amount being larger than the first operation amount, the transmission device does not steers the front wheel regardless of the operation of the steering wheel. The steering of the front wheel is thereby limited in the middle and the occurrence of unstable travelling state such as skid is prevented, and the front wheel can be greatly steered if needed.

Description

  The present invention relates to a steering system for a vehicle.

  In recent years, a steering system mounted on a vehicle includes a steering system that restricts a steering operation so as to narrow an operation range of an operation member operated by a driver, that is, a wheel system that narrows a wheel turning range. Steering systems that restrict steering are being developed. For example, in the steering system described in the following patent document, the steering range of the wheel is narrowed according to the vehicle speed, etc., thereby preventing the steering amount of the wheel from becoming unnecessarily large when turning the vehicle. This prevents the vehicle from falling into an unstable running state such as a skid.

Japanese Utility Model Publication No. 61-56169 Japanese Patent Laid-Open No. 2-117467 JP-A-6-183361

  The steering system described in the above-mentioned patent document restricts the steering operation and the wheel turning according to the situation in which the vehicle is used. Therefore, if steering operation and wheel steering are restricted in consideration of other situations and vehicle characteristics, a highly practical steering system suitable for those situations and characteristics can be obtained. In view of such circumstances, the present invention has an object to provide a highly practical steering system.

  In order to solve the above problems, a steering system according to the present invention includes an operating device having an operating member operated by a driver, a steering device that steers the wheel while holding the wheel rotatably, and an operating member. The operation-based steering realizing means for realizing the wheel steering by the steering device according to the operation of the steering device, and the operation-based steering realizing means has an operation amount of the operating member from the state in which the vehicle goes straight. In the case where the operation amount is between one operation amount and a second operation amount larger than the first operation amount, the wheel is not steered regardless of the operation of the operation member.

  In brief, in the steering system of the present invention, when the operation member is operated from a state in which the vehicle goes straight, a state in which the turning of the wheels is interrupted occurs. For example, as will be described in detail later, a vehicle in which four wheels are arranged at the apex of a rhombus can turn on the spot by turning the front and rear wheels so as to face each side. On the other hand, if the vehicle is steered until the wheels turn to the side during running, it will fall into an unstable running state such as skidding. According to the present steering system, in such a vehicle, it is possible to prevent the wheel from being steered so as to make the running of the vehicle unstable by interrupting the wheel steering halfway. Further, if the steering system is configured to be steered until the front and rear wheels are turned to the side when the operation member is operated beyond the second operation amount, the wheel is turned to the side if necessary. The front and rear wheels can be steered. As described above, this steering system is adapted to the characteristics of the vehicle and the situation in which it is used, and is highly practical.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. Some of the aspects of the claimable invention correspond to the invention according to the claims described in the claims.

  In the following items, items (1) to (8) correspond to claims 1 to 8, respectively.

(1) A steering system for turning a wheel by a driver's operation, the operating device having an operating member operated by the driver;
A steering device that steers the wheel while holding the wheel rotatably,
Operation-based steering realizing means for realizing the steering of the wheel by the steering device according to the operation of the operating member,
When the operation-based steering realizing means has an operation amount of the operation member from a state in which the vehicle goes straight between a first operation amount and a second operation amount larger than the first operation amount. A steering system configured not to steer the wheel regardless of the operation of the operation member.

  In the steering system of the present invention, when the operation member is operated from a state where the vehicle goes straight, the wheels are steered until the operation amount of the operation member reaches the first operation amount, and the second operation amount is changed from the first operation amount to the second operation amount. The wheel is not steered until the operation amount is reached, and the wheel is steered again when the operation amount becomes larger than the second operation amount. Therefore, when the operation member is operated from the state where the vehicle goes straight, the wheel is turned in the middle of the state where the wheel is allowed to be steered (hereinafter sometimes referred to as “steering permissible state”). An interrupted state (hereinafter sometimes referred to as a “steering interrupted state”) occurs. In other words, in the steering system of the present invention, the dead zone between the first operation amount and the second operation amount is a dead zone in which the wheel is not steered with respect to the operation of the operation member. Therefore, the present steering system can prevent the wheel turning amount from becoming unnecessarily large by restricting the wheel turning during the operation of the operation member. Further, if necessary, the wheel can be steered again by largely manipulating the operating member, and thus the wheel can be steered greatly. Therefore, this steering system is suitable for the characteristics of the vehicle and the situation in which it is used, and is highly practical.

  The steering system may be mounted on a general vehicle, that is, a vehicle in which wheels are arranged at the four corners of the vehicle body. For example, a vehicle in which four wheels are arranged at the apexes of a rhombus, That is, it is assumed that the vehicle is mounted on a vehicle having front and rear wheels that are steered wheels and wheels that are arranged on the left and right in the middle of the front and rear wheels. This vehicle has a feature that it can turn on the spot by turning the front and rear wheels 90 degrees, that is, to turn to the side. On the other hand, if the front and rear wheels are steered while facing the vehicle while the vehicle is traveling, the vehicle is put into an unstable traveling state in which skidding or the like occurs. According to the present steering system, it is possible to prevent such an unstable traveling state from occurring by restricting the steering of the wheel on the way. Further, in a situation where it is desired to turn on the spot, the front and rear wheels can be steered until the vehicle is turned sideways by operating the operation member beyond the second operation amount. Thus, this steering system is highly practical, particularly for vehicles in which four wheels are arranged at the apexes of the rhombus.

(2) The operating device includes an input shaft that is coupled to the operating member and rotates according to the operation of the operating member;
The steering device has an output shaft that steers the wheel by its rotation,
The operation-based steering realizing means is
A rotation transmission mechanism that has a driving body that rotates together with the input shaft and a driven body that rotates together with the output shaft, and that the driving body and the driven body engage with each other to transmit the rotation of the input shaft to the output shaft. And
The rotation transmission mechanism is configured to release the engagement between the driving body and the driven body when the operation amount is between the first operation amount and the second operation amount ( The steering system according to item 1).

  In the present steering system, the driving body and the driven body are engaged with each other, so that the wheel is steered by the operation of the operation member. The structure of the rotation transmission mechanism is not particularly limited. When the operation amount is not between the first operation amount and the second operation amount, the driving body and the driven body are engaged with each other. It only has to be configured. For example, the rotation transmission mechanism is a mechanism in which the driving body and the driven body are directly engaged, such as a gear mechanism or a cam mechanism, or a driving body and a driven body, such as a belt mechanism or a chain mechanism. And a mechanism that engages indirectly via a belt, a chain, or the like.

(3) The driving body and the driven body are arranged such that their respective rotation axes are parallel to each other,
The prime mover has a pin that extends in a direction parallel to the rotational axis at a position deviated from the rotational axis of the prime mover and rotates around the rotational axis of the prime mover as the input shaft rotates;
The follower has a plurality of slots formed radially around the rotation axis of the follower and each opening at an outer periphery of the follower;
The rotation transmission mechanism is
When the pin enters one of the plurality of slots, the driving body and the driven body engage with each other, and when the pin escapes from one of the plurality of slots, the original The moving body and the driven body are disengaged from each other; and
When the vehicle is traveling straight, the pin is positioned inside one of the plurality of slots, and the pin is one of the plurality of slots when the operation member is operated to the first operation amount. In the item (2), the pin is configured to enter a slot different from one of the plurality of slots when the operation member is further operated to the second operation amount when the operation member is further operated to the second operation amount. The described steering system.

  In this steering system, the rotation transmission mechanism is configured as a kind of gear mechanism. In this steering system, as the input shaft rotates, it can be considered that the pin of the prime mover circulates on a circular orbit around the rotational axis of the prime mover (hereinafter, this orbit is referred to as a “circular orbit”). May say). Further, it can be considered that the plurality of slots are provided in the driven body so as to intersect with the circular orbit as the output shaft rotates. Therefore, when the pin is in any one of the plurality of slots, the pin is caught in the slot, so that the driven body rotates as the driving body rotates. That is, the driving body and the driven body are engaged, and the rotation of the input shaft can be transmitted to the output shaft. When the operation member is operated to the first operation amount, the opening of the slot is positioned on the circular track with the rotation of each of the driving body and the driven body, and the pin escapes from the slot. Therefore, the engagement between the driving body and the driven body is released, and the steering system is in a steering suspension state. When the operating member is further operated, the pin that rotates on the orbit is separated from the driven body and approaches the driven body again. In the rotation transmission mechanism of the present steering system, the follower is configured such that the opening of the slot different from the slot from which the pin has escaped is positioned on the orbit. Therefore, when the operating member is operated to the second operation amount, the pin enters the other slot, so that the pin is again caught in the slot, and the rotation of the input shaft is again applied to the output shaft. Can be transmitted. The rotation transmission mechanism using pins and slots can be considered as a mechanism using a part of the geneva mechanism.

  (4) The rotation transmission mechanism includes an output shaft rotation prohibiting mechanism that prohibits rotation of the output shaft when the operation amount is between the first operation amount and the second operation amount. The steering system according to item (3).

  According to this steering system, when the operation amount is between the first operation amount and the second operation amount, that is, in the steering interruption state, for example, the wheels are steered because the wheels have passed a step or the like. Even if the external force acts on the wheel, the wheel will not be steered. In addition, when the output shaft is prohibited from rotating, the driven body is also prohibited from rotating. For example, in the case of the above-described driven body having a plurality of slots, the driven body rotates in a steering suspension state. In addition, it is possible to prevent the openings of the two slots from being displaced from the orbit.

(5) The output shaft rotation prohibiting mechanism is provided on the prime mover and is formed in an arc shape centered on the rotation axis of the prime mover; and the latch is provided on the follower. Having a locked portion formed in a curved shape that fits,
In the rotation transmission mechanism, when the operation amount is between the first operation amount and the second operation amount, the driving body and the driven body are arranged such that the locked portion and the locking portion face each other. Each body is configured to be rotated,
When the operation amount is between the first operation amount and the second operation amount, the output shaft rotation prohibiting mechanism causes the output portion of the output shaft to come into contact with the engagement portion. The steering system according to item (4), which is configured to prohibit rotation.

  In this steering system, it can be considered that the locking portion is formed in a convex shape, and the locked portion is formed in a concave shape that fits the convex shape. When the driving body and the driven body are rotated so that the locked portion and the locking portion that are formed in such a shape face each other in a state where the steering is interrupted, a convex shape is formed in the concave locked portion. The locking portion is fitted, and the driven body cannot be rotated. That is, the rotation of the driven body is prohibited, and accordingly, the rotation of the output shaft is prohibited. On the other hand, even in the state where the locked portion and the locking portion face each other, the surface of the locking portion that faces the locked portion is formed in an arc shape centering on the rotation axis of the prime mover, The prime mover can rotate while the locking portion is in sliding contact with the locked portion. That is, the rotation of the input shaft is allowed even in the steering interruption state. Therefore, for example, in the case of the above-mentioned driven body having a plurality of slots, the rotation of the driven body is prohibited while the rotation of the driven body is prohibited in the steering interruption state, that is, in the state where the two slots are respectively opened on the orbit. In other words, the rotation of the pin on the orbit is permitted.

  Further, in order to allow rotation of the driven body in the steerable state, the driving body contacts the driven body except for the pins when the operation amount is not between the first operation amount and the second operation amount. It is desirable to have a shape that does not occur. In such a driving body, in the steerable state, for example, the outer peripheral portion of the driven body comes into contact with the outer peripheral portion of the driving body, so that the rotation of the driven body is not hindered. Therefore, in the case of the driving body of the present steering system in which the locking portion has an arc shape, the portion other than the locking portion is a notched portion, that is, a portion that is shaped like a circular arc. Is desirable. By making the prime mover in such a shape, the prime mover does not contact the follower except for the pins in the steering-permitted state, and the rotation of the follower is not hindered. Note that the output shaft rotation prohibiting mechanism using the arc-shaped locking portion and the locked portion formed in a curved shape in which the locking portion fits is considered as a mechanism using a part of the Geneva mechanism. It is something that can be done.

  (6) The steering system according to any one of (2) to (5), wherein the rotation transmission mechanism is a geneva mechanism.

  Since the rotation transmission mechanism of the present steering system is a geneva mechanism, it can be considered that the rotation transmission mechanism has various configurations. That is, the rotation transmission mechanism of the present steering system has a locked portion when the driving body and the driven body are engaged when the pin enters the slot, and the pin is removed from the slot. While the driven body is prohibited from rotating, the driving body having the locking portion is allowed to rotate.

(7) The turning device has a power source for turning the wheels,
The operation-based steering realizing means is configured by an operation amount detector that detects an operation amount of the operation member, and a control device that controls the power source based on the operation amount,
The steering according to (1), wherein the control device controls the power source so as not to steer the wheel when the operation amount is between the first operation amount and the second operation amount. system.

  It can be considered that the present steering system is a so-called steer-by-wire type steering system. That is, in this steering system, for example, an operation amount detector such as a sensor and a power source such as a motor are provided, and the control device steers the wheel or turns the wheel based on the operation amount. The motor is controlled so as not to be steered. In the steering device, the power source may be configured to steer the wheels via a reduction gear or the like. When a reduction gear is used, it is desirable that its reduction ratio is relatively large, that is, the reverse efficiency is relatively large. With such a speed reducer, it is possible to prohibit the turning of the wheel with a relatively small power even when an external force for turning the wheel acts on the wheel in the steering interruption state.

(8) One forward steered wheel positioned forward and steered, one rear steered wheel positioned rearward and steered, and left and right between the front steered wheel and the rear steered wheel, respectively In a vehicle having two non-steered wheels arranged,
The steering system according to any one of (1) to (7), wherein the vehicle is equipped to steer at least one of the front steered wheels and the rear steered wheels.

  According to the aspect of this section, at least one of the two steered wheels of the vehicle in which the four wheels are arranged at the apex of the rhombus is steered by any of the aforementioned steering systems. . The other of the two steered wheels may be steered by any of the aforementioned steering systems, or may be steered by something like a mechanism that operates in conjunction with a steering system that steers one steered wheel. May be. If the above-described vehicle has such a configuration, the vehicle can turn on the spot, and can prevent the wheel from being steered so that the traveling of the vehicle becomes unstable.

It is a top view which shows the vehicle carrying the steering system of 1st Example. It is a perspective view which shows the steering system of 1st Example. It is a figure which shows a mode that the state of the rotation transmission mechanism which the steering system of 1st Example has changes with operation of an operation member. In the steering system of 1st Example, it is a graph which shows the change of the turning amount of the wheel with respect to the change of the operation amount of an operation member. It is a perspective view which shows the steering system of 2nd Example.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. The claimable invention is not limited to the following examples and modifications, and can be implemented in various modes with various changes and improvements based on the knowledge of those skilled in the art.

≪Configuration of vehicle with steering system≫
FIG. 1 schematically shows a vehicle 12 on which the steering system 10 of the embodiment is mounted. The vehicle 12 has four wheels 14, and each of the four wheels 14 is disposed so as to be located at the apex of the rhombus. Specifically, the vehicle 12 is arranged on the left side of the vehicle between the front wheel 14F disposed on the front side of the vehicle, the rear wheel 14R disposed on the rear side of the vehicle, and the front wheel 14F and the rear wheel 14R. It has a left wheel 14ML provided and a right wheel 14MR disposed on the right side. Although detailed description is omitted, the vehicle 12 is provided with a suspension device and a brake device corresponding to each of the four wheels 14. Of the four wheels 14, the left wheel 14ML and the right wheel 14MR are drive wheels in the vehicle. Each of the left wheel 14ML and the right wheel 14MR is provided with a drive device having a motor as a drive source. Although a detailed description is omitted, the drive device drives the left wheel 14ML and the right wheel 14MR with a motor force according to the driver's accelerator operation. Further, the drive device is configured such that the left wheel 14ML and the right wheel 14MR can be independently driven. The front wheels 14F and the rear wheels 14R are respectively steered wheels in the vehicle 12. FIG. 1 shows a state where the front wheels 14F and the rear wheels 14R are not steered, that is, a state where the vehicle 12 goes straight.

  The vehicle 12 has a feature that if the front wheel 14F and the rear wheel 14R are each turned 90 °, that is, turn rightward, they can turn on the spot. When turning in such a manner, it is necessary to rotationally drive the left wheel 14ML and the right wheel 14MR in directions different from each other, and the vehicle 12 has a switch for rotating the left wheel 14ML and the right wheel 14MR as described above. It is provided near the driver's seat. On the other hand, when the vehicle 12 is traveling, if the front wheel 14F and the rear wheel 14R are turned to the side or if the vehicle 12 is steered considerably large, the vehicle 12 is in an unstable traveling state such as a skid. There is a risk of falling.

≪Steering system configuration≫
FIG. 2 schematically shows the steering system 10 for turning the front wheels 14F. The steering system 10 roughly includes an operation device 16 to which an operation by the driver is input, a front wheel steering device 18 that steers the front wheel 14F while rotatably holding the front wheel 14F, and an operation device 16. The transmission device 20 is configured to transmit an input operation to the front wheel steering device 18.

  The operating device 16 includes a housing 22 fixed to the vehicle body, an operating shaft 24 rotatably held in the housing 22, and a steering wheel 26 fixed to one end of the operating shaft 24. Yes. The steering wheel 26 is an operation member operated by the driver, and the operation shaft 24 rotates in accordance with the operation. The operation device 16 includes an intermediate shaft 28 having one end connected to the other end of the operation shaft 24, and one end connected to the other end of the intermediate shaft 28. And a transmission shaft 30 having ends connected to each other. A universal joint is used to connect these shafts. An assisting device 34 for assisting the rotation of the steering wheel 26 is attached to the front of the housing 22. Although a detailed description is omitted, the assisting device 34 has a motor and generates a motor force corresponding to the force of the driver operating the steering wheel 26. The motor force is applied to the operation shaft 24, and the rotation operation of the steering wheel 26 by the driver is assisted. That is, the assisting device 34 constitutes a so-called power steering device.

  The front wheel steering device 18 includes a pair of wheel holding columns 36 that hold the axle shaft at one end, a bridge 38 that holds the other end of each wheel holding column 36, and one end at the center of the bridge 38. The column shaft 40 is provided upright. The front wheel 14 </ b> F is rotatably held by an axle shaft passed to the pair of wheel holding columns 36. The column shaft 40 is rotatably held by a shaft holder 42 fixed to the vehicle body. With the front wheel steering device 18 configured as described above, the front wheel 14F is steered when the column shaft 40 is rotated. Although not described in detail, each of the wheel holding columns 36 includes a compression coil spring and an oil damper, and the front wheel steering device 18 elastically supports the front wheels 14F with respect to the vehicle body. It also has a function as a suspension device. The other end of the column shaft 40 is provided with two locked pins 44 that protrude in the radial direction. These two locked pins 44 rotate when the column shaft 40 rotates, and the shaft holding portion 42. It abuts on a locking plate 46 provided on the surface. Due to the contact, the column shaft 40 does not rotate so as to be steered beyond 90 ° from the state in which the front wheel 14F is traveling straight. In other words, the two locked pins 42 and the locking plate 46 constitute a stopper mechanism that prohibits excessive steering of the front wheel 14F.

  The vehicle 12 is also provided with a rear wheel steering device 48 that steers the rear wheels 14R. The rear wheel steering device 48 has the same configuration as the front wheel steering device 18, and the rear wheel 14R is steered when the column shaft 50 is rotated. The rear wheel steering device 48 is connected to the front wheel steering device 18 so that the rear wheel 14R can be steered in conjunction with the front wheel steering device 18. More specifically, a front wheel side pulley 52 having a groove around which a wire can be hooked is fixed to the column shaft 40 of the front wheel steering device 18. On the other hand, a rear wheel pulley 54 having the same size as the front wheel pulley 52 is fixed to the column shaft 50 of the rear wheel steering device 48. One end of two wires 56 that connect the front wheel steering device 18 and the rear wheel steering device 48 are fixed to the front wheel side pulley 52 on either side of the column shaft 40. The other ends of the two previous wires 56 are fixed to the rear wheel side pulley 54 on the left and right sides of the column shaft 50, respectively. The two wires 56 are respectively fixed to the front wheel side pulley 52 and the rear wheel side pulley 54 so as to cross each other in the middle. When the column shaft 40 of the front wheel steering device 18 is rotated by the front wheel side pulley 52 and the rear wheel side pulley 54 thus connected by the two wires 56, the column shaft 50 of the rear wheel steering device 48 is The rotation direction is opposite to the rotation direction of 40. In other words, in the vehicle 12, a mechanism for turning the rear wheel 14R in conjunction with the front wheel 14F is constituted by the front wheel side pulley 52, the rear wheel side pulley 54, and the two wires 56.

  The transmission device 20 can be considered as a so-called Geneva mechanism. The transmission device 29 includes an operation side gear 60 fixed to the transmission shaft 30 of the operation device 16 and a steering side gear 62 fixed to the column shaft 40 of the front wheel steering device 18. The operation side gear 60 has a structure in which two plates having different shapes are stacked, and a lower plate portion 64 having a disk shape through which the rotation axis of the transmission shaft 30 penetrates the center of the operation side gear 60, And an upper plate portion 66 provided so as to overlap the upper surface of the lower plate portion 64. The upper plate portion 66 is formed in an arc shape centered on the rotation axis of the transmission shaft 30, and a part thereof is cut out of the arc. Further, a pin extending in a direction parallel to the rotation axis is located on the side of the upper plate portion 66 of the operation side gear 60 and on the upper surface of the lower plate portion 64, in other words, at a position shifted from the rotation axis of the operation side gear 60. 68 is erected.

  On the other hand, in the steered side gear 62, four slots 74 that are radially formed around its own rotation axis are formed at equal intervals in the circumferential direction, that is, at 90 ° intervals. Each slot 74 is open at the outer periphery of the steered side gear 62, and the width of each slot 74 is slightly larger than the diameter of the pin 68. Further, the outer peripheral portion of the steered side gear 62 is formed so as to be recessed in the central direction of the steered side gear 62 except for the portion where the openings of the four slots 74 are formed. Therefore, the steered side gear 62 is shaped such that the opening of each slot 74 projects in the radial direction. Note that the recessed portions of the steered side gear 62 are each formed in a curved shape into which the arc-shaped portion of the upper plate portion 66 is fitted.

  In the transmission device 20, the operation side gear 60 and the steered side gear 62 are arranged such that a part of each of them overlaps. More specifically, on the operation side, a part of the operation side gear 60 and a part of the steered side gear 62 overlap each other above the lower plate part 64 of the operation side gear 60 and on the side of the upper plate part 66. The gear 60 and the steered side gear 62 are arranged. Further, when the front wheel 14F and the rear wheel 14R are not steered, the pin 68 is located on a line connecting the center axis of the transmission shaft 30 and the center axis of the column shaft 40, and the steered side gear 62 The operation side gear 60 and the steered side gear 62 are respectively connected to the transmission shaft 30 and the column shaft 40 so as to be in a state (shown in FIGS. 1 and 2) located in any one of the four slots 74. It is fixed to.

  When the steering wheel 26 is operated and the transmission shaft 30 rotates in the operation side gear 60 and the steered side gear 62 arranged in this way, the pin 68 is caught in the slot 74, so that the column shaft 40 is It will be rotated. That is, the operation side gear 60 and the steered side gear 62 are engaged with each other by the catch, and the rotation of the transmission shaft 30 is transmitted to the column shaft 40. That is, in the transmission device 20, the operation side gear 60 is a driven body that rotates together with the transmission shaft 30 that is an input shaft, and the steered side gear 62 is a driven body that rotates together with the column shaft 40 that is an output shaft. The device 20 is a rotation transmission mechanism in which the operation side gear 60 and the steered side gear 62 are engaged to transmit the rotation of the transmission shaft 30 to the column shaft 40. Therefore, when the driver operates the steering wheel 26, the front wheels 14F are steered. Therefore, the transmission device 20 is an operation-based steering realizing unit that realizes the steering of the front wheel 18 by the front wheel steering device 18 in accordance with the operation of the steering wheel 26. When the front wheel side pulley 52 is rotated along with the rotation of the column shaft 40, the wire 56 is pulled, so that the rear wheel side pulley 54 is rotated. That is, the rear wheel 14R is steered together with the steering of the front wheel 14F.

  FIG. 3 is a diagram illustrating how the operating side gear 60 and the steered side gear 62 rotate when the steering wheel 26 is rotated leftward from a state in which the steering wheel 26 is not operated. FIG. 3A shows a state where the front wheels 14F are not steered, that is, a state where the steering wheel 26 is in the neutral position. When the steering wheel 26 is rotated counterclockwise from the neutral position, the pin 68 moves on a circular orbit (shown by a broken line in FIG. 3) around the rotation axis of the operation side gear 60. Become. Therefore, as the operation side gear 60 and the steered side gear 62 rotate, the pin 68 moves toward the opening of the slot 74 located inside as shown in FIG. 3B. become. When the steering wheel 26 is further rotated counterclockwise, as shown in FIG. 3C, the pin 68 reaches the opening of the slot 74 in which the pin 68 is located and escapes from the slot 74. That is, the engagement between the operation side gear 60 and the steered side gear 62 is released in a state where the operation side gear 60 and the steered side gear 62 are in the rotational positions shown in FIG. become. Therefore, even if the steering wheel 26 is further rotated counterclockwise, as shown in FIG. 3D, the rotational position of the steered side gear 62 does not change from the rotational position shown in FIG. Only 60 will rotate. Further, when the steering wheel 26 is rotated counterclockwise until the state shown in FIG. 3 (e), the pin 68 opens in a slot 74 different from the slot 74 that has escaped in the state shown in FIG. 3 (c). Moved to. Therefore, when the steering wheel 26 is further rotated counterclockwise, as shown in FIG. 3F, the pin 68 enters the other slot 74, and the pin 68 is caught in the other slot 74. It becomes. That is, the rotation of the transmission shaft 30 is transmitted again to the column shaft 40, and the front wheel 14F and the rear wheel 14R can be steered again by the operation of the steering wheel 26.

  Further, in the state shown in FIGS. 3C to 3E, the operation side gear 60 and the recessed portion of the steered side gear 62 face each other so that the arc-shaped portion of the upper plate portion 66 of the operation side gear 60 faces each other. The gear 60 and the steered side gear 62 are rotated. The arc-shaped portion of the operation side gear 60 can be considered as a convex portion that fits into the recessed portion of the steered side gear 62, and the arc-shaped portion of the operation side gear 60 and the steered side gear The arc-shaped portion of the operation side gear 60 is fitted into the recessed portion of the steered side gear 62 in a state where the recessed portions of 62 face each other. Therefore, in the state shown in FIGS. 3C to 3E, the recessed portion of the steered side gear 62 comes into contact with the arc-shaped portion of the operating side gear 60, and the rotation of the column shaft 40 is prohibited. become. In other words, the arc-shaped portion of the operation side gear 60 is a locking portion, and the recessed portion of the steered side gear 62 is a locked portion that is locked to the arc-shaped portion of the operation side gear 60. Can be thought of as Further, in the transmission device 20, an output shaft rotation prohibiting mechanism that prohibits rotation of the column shaft 40 that is an output shaft is configured by the recessed portion of the steered side gear 62 and the arc-shaped portion of the operation side gear 60. Can be considered. Therefore, in the state shown in FIGS. 3C to 3E, for example, even if the front wheel 14F passes through a step or the like and an external force that acts to steer the front wheel 14F is generated, the front wheel 14F is rotated. In this case, the rear wheel 14R is not rotated.

  On the other hand, even in the state shown in FIGS. 3C to 3E, that is, in the state where the arc-shaped portion of the operation side gear 60 faces the recessed portion of the steering side gear 62, the operation side gear 60 is The arc-shaped portion can be rotated while being in sliding contact with the recessed portion of the steered side gear 62. That is, the operation of the steering wheel 26 is allowed. 3B and 3F, that is, in a state where the pin 68 is located in the slot 74, the notched portion of the operation side gear 60 is the slot of the steering side gear 62. It is formed so as to be separated from a portion where the opening 74 is located, that is, a portion protruding in the radial direction of the operation side gear 60. Therefore, when the pin 68 is located in any of the slots 74, the operation side gear 60 does not contact the steered side gear 62 except for the pin 68, and the rotation of the steered side gear 62 is prevented. There is nothing.

  If the steering wheel 26 is rotated clockwise from a state where it is not operated, the operation side gear 60 and the steered side gear 62 are disengaged from each other as in the case of left rotation, and are engaged again. Will match.

  FIG. 4 shows the relationship between the operation amount and the turning amount realized by the steering system 10 in the coordinates where the horizontal axis is the operation amount of the steering wheel 26 and the vertical axis is the turning amount of the front wheel 14F. It is a graph. As shown in this graph, in the transmission device 20, in the vicinity of the state in which the vehicle 12 goes straight, a steering permission state, that is, a state in which the steering of the front wheels 14F is permitted in accordance with the operation of the steering wheel 26 is realized. The When the steering wheel 26 is operated to the first operation amount, that is, the state where the pin 68 is positioned at the opening of the slot 74, as shown in FIG. A state in which the turning of the front wheel 14F in response to the operation of the steering wheel 26 is interrupted is realized. Then, as shown in FIG. 3E, the steering wheel 26 has a larger operation amount than the first operation amount, that is, as shown in FIG. When the operation is performed up to the position, the transmission device 20 realizes the turning permission state again. In other words, in the present steering system 10, a dead zone in which the front wheel 14 </ b> F is not steered with respect to the operation of the steering wheel 26 is between the first operation amount and the second operation amount. When the operation side gear 60 and the steered side gear 62 rotate together in the steerable state, the pin 68 moves in the slot 74 in the direction in which the slot 74 extends. Therefore, as the pin 68 moves, the position where the operation side gear 60 and the steered side gear 62 are engaged changes. Therefore, the ratio between the rotation amount of the operation side gear 60 and the rotation amount of the steered wheel 62, that is, the ratio between the operation amount of the steering wheel 26 and the steered amount of the front wheel 14F is shown in the steerable state of FIG. Thus, it changes according to the operation amount of the steering wheel 26.

  Therefore, the present steering system 10 restricts the turning of the front wheels 14F when the steering wheel 26 is operated to the first operation amount. Therefore, according to the present steering system 10, the front wheel 14 </ b> F and the rear wheel that make the traveling of the vehicle 12 unstable even if the driver operates the steering wheel 26 beyond the first operation amount while the vehicle is traveling. Steering of the wheel 14R can be prevented. Further, if necessary, if the steering wheel 26 is operated beyond the second operation amount, the front wheel 14F and the rear wheel 14R can be steered again, and the front wheel 14F and the rear wheel 14R can be turned 90 °, that is, directly beside. It can be steered until it turns. Therefore, in a situation where it is desired to turn the vehicle 12 on the spot, the front wheel 14F and the rear wheel 14R can be steered until they turn sideways, and the vehicle 12 can be turned on the spot.

≪Configuration of vehicle with steering system≫
FIG. 5 schematically shows a modified steering system 80. Similar to the steering system 10 of the first embodiment, the steering system 80 is a steering system for turning the front wheels 14F of the vehicle 12. Most of the configuration of the steering system 80 is the same as that of the steering system 10 of the first embodiment. Therefore, in the following description of the steering system 80, the description of the same equipment and configuration as the steering system 10 of the first embodiment is omitted for the sake of simplifying the specification.

≪Steering system configuration≫
The steering system 80 roughly includes an operation device 82 to which an operation by the driver is input, a front wheel steering device 84 that can turn the front wheel 14F while holding the front wheel 14F rotatably, The steering ECU 86 is configured to control the front wheel steering device 84 to operate in accordance with an operation input to the device 82.

  The operating device 82 has a reaction force applying motor 88 in front of the housing 22. The steering wheel 26 and the reaction force applying motor 88 are connected by an input shaft that is rotatably held in the housing 22. Although a detailed description is omitted, the reaction force application motor 88 generates a rotational force against the steering wheel 26 when the steering wheel 26 is operated. The rotational force is applied to the steering wheel 26 via the input shaft. That is, the rotational force is applied to the steering wheel 26 as an operation reaction force with respect to the operation of the steering wheel 26.

  The front wheel steering device 84 includes a steering motor 90 fixed to the vehicle body as a power source, a worm 92 fixed to the motor shaft of the steering motor 90, and a worm fixed to the column shaft 40 in mesh with the worm 92. And a wheel 94. That is, in the front wheel steering device 84, the worm 92 and the worm wheel 94 constitute a worm gear mechanism. The worm gear mechanism functions as a speed reducer, and the rotation of the steering motor 90 is decelerated and transmitted to the column shaft 40. That is, the column shaft 40 rotates at a speed reduced with respect to the rotation speed of the steering motor 90, and the front wheels 14F are steered along with the rotation. The worm gear mechanism constituted by the worm 92 and the worm wheel 94 has a relatively high reverse efficiency. Therefore, even if an external force for turning the front wheel 14F acts on the front wheel 14F, the steering motor 90 only generates a relatively small motor force and prohibits the front wheel 14F from being steered by the external force. it can. Although not shown, the rear wheel steering device that rotatably holds the rear wheel 14R has the same configuration as that of the front wheel steering device 84, and the rear wheel steering device is rotated by rotation of the steering motor of the rear wheel steering device. The wheel 14R is steered.

  The steering system 80 includes an operation amount sensor 96 for detecting the operation amount of the steering wheel 26, and the operation amount sensor 96 is connected to the steering ECU 86. The operation amount sensor 96 is provided in the housing 22 of the operation device 82, and as an operation amount detector, detects an operation amount of the steering wheel 26 based on the rotational position of the input shaft. Further, the steering ECU 86 is also connected to the steering motor 90 of the front wheel steering device 84, so that the steering motor 90 operates it based on a signal output from the operation amount sensor 96 as a control device. The signal is output. That is, the operation amount sensor 96 and the steering ECU 86 constitute an operation-based steering realizing unit that realizes the steering of the front wheel 14F by the front wheel steering device 84 according to the operation of the steering wheel 26. Incidentally, the steering motor of the rear wheel steering device is also connected to the steering ECU 86, and the steering motor is operated so that the rear wheel 14R is steered by the same amount in the direction opposite to that of the front wheel 14F. Is output. The reaction force application motor 88 is also connected to the steering ECU 86, and outputs a signal for operating the reaction force application motor 88 so as to generate an operation reaction force corresponding to the operation of the steering wheel 26.

  In the steering system 80 configured as described above, based on the detection amount detected by the operation amount sensor 96, the operation amount of the steering wheel 26 and the turning amount of the front wheel 14 have the relationship shown in the graph of FIG. As described above, the steering ECU 86 outputs a signal to the steered motor 90. That is, in the vicinity of the state in which the vehicle 12 travels straight, the steerable state is realized, and when the steering wheel 26 is operated to the first operation amount, the steering interruption state is realized, and the operation amount is larger than the first operation amount. When the second operation amount is operated, the steered motor 90 is operated so that the steerable state is realized again.

  Accordingly, the steering system 80 limits the turning of the front wheels 14F when the steering wheel 26 is operated to the first operation amount. Therefore, according to the present steering system 80, the front wheel 14 </ b> F that makes the traveling of the vehicle 12 unstable even if the driver operates the steering wheel 26 beyond the first operation amount during the traveling of the vehicle 12. Steering of the rear wheel 14R can be prevented. Further, if necessary, if the steering wheel 26 is operated beyond the second operation amount, the front wheel 14F and the rear wheel 14R can be steered again, and the front wheel 14F and the rear wheel 14R can be turned 90 °, that is, directly beside. It can be steered until it turns. Therefore, in a situation where it is desired to turn the vehicle 12 on the spot, the front wheel 14F and the rear wheel 14R can be steered until they turn sideways, and the vehicle 12 can be turned on the spot.

  10: Steering system 14: Wheel 16: Operation device 18: Front wheel steering device (steering device) 20: Transmission device (rotation transmission mechanism, operation-based transmission means) 26: Steering wheel (operation member) 30: Transmission shaft (input) Shaft) 40: Column shaft (output shaft) 60: Operation side gear (prime body) 62: Steering side gear (driven body) 68: Pin 74: Slot 80: Steering system 82: Operating device 84: Front wheel steering device ( Steering device) 86: Steering ECU (control device, operation-dependent transmission means) 90: Steering motor (power source) 96: Operation amount sensor (operation amount detector, operation-based transmission means)

Claims (8)

A steering system for turning wheels by a driver's operation,
An operating device having an operating member operated by a driver;
A steering device that steers the wheel while holding the wheel rotatably,
Operation-based steering realizing means for realizing the steering of the wheel by the steering device according to the operation of the operating member,
When the operation-based steering realizing means has an operation amount of the operation member from a state in which the vehicle goes straight between a first operation amount and a second operation amount larger than the first operation amount. A steering system configured not to steer the wheel regardless of the operation of the operation member. The operating device has an input shaft coupled to the operating member and rotating in response to an operation of the operating member;
The steering device has an output shaft that steers the wheel by its rotation,
The operation-based steering realizing means is
A rotation transmission mechanism that has a driving body that rotates together with the input shaft and a driven body that rotates together with the output shaft, and that the driving body and the driven body engage with each other to transmit the rotation of the input shaft to the output shaft. And
The rotation transmission mechanism is configured to release the engagement between the driving body and the driven body when the operation amount is between the first operation amount and the second operation amount. Item 2. The steering system according to Item 1. The driving body and the driven body are arranged such that their respective rotation axes are parallel to each other,
The prime mover has a pin that extends in a direction parallel to the rotational axis at a position deviated from the rotational axis of the prime mover and rotates around the rotational axis of the prime mover as the input shaft rotates;
The follower has a plurality of slots formed radially around the rotation axis of the follower and each opening at an outer periphery of the follower;
The rotation transmission mechanism is
When the pin enters one of the plurality of slots, the driving body and the driven body engage with each other, and when the pin escapes from one of the plurality of slots, the original The moving body and the driven body are disengaged from each other; and
When the vehicle is traveling straight, the pin is positioned inside one of the plurality of slots, and the pin is one of the plurality of slots when the operation member is operated to the first operation amount. 3. The device according to claim 2, wherein the pin is configured to enter a slot different from one of the plurality of slots when the operation member is further operated to the second operation amount when the operation member is further operated to the second operation amount. Steering system.   4. The rotation transmission mechanism includes an output shaft rotation prohibiting mechanism that prohibits rotation of the output shaft when the operation amount is between the first operation amount and the second operation amount. The described steering system. The output shaft rotation prohibiting mechanism is provided on the prime mover and is formed in an arc shape centered on the rotation axis of the prime mover, and the follower is provided on the follower and the latching portion is fitted. A locked portion formed in a curved shape,
In the rotation transmission mechanism, when the operation amount is between the first operation amount and the second operation amount, the driving body and the driven body are arranged such that the locked portion and the locking portion face each other. Each body is configured to be rotated,
When the operation amount is between the first operation amount and the second operation amount, the output shaft rotation prohibiting mechanism causes the output portion of the output shaft to come into contact with the engagement portion. The steering system according to claim 4, wherein the steering system is configured to inhibit rotation.   The steering system according to any one of claims 2 to 5, wherein the rotation transmission mechanism is a geneva mechanism. The steering device has a power source for turning wheels,
The operation-based steering realizing means is configured by an operation amount detector that detects an operation amount of the operation member, and a control device that controls the power source based on the operation amount,
The steering system according to claim 1, wherein the control device controls the power source so as not to steer the wheel when the operation amount is between the first operation amount and the second operation amount. . One front steered wheel positioned forward and steered, one rear steered wheel positioned rearward and steered, and disposed between the front steered wheel and the rear steered wheel on the left and right, respectively. In a vehicle with two non-steering wheels
The steering system according to any one of claims 1 to 7, wherein the steering system is mounted on the vehicle to steer at least one of the front steered wheels and the rear steered wheels.

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