JP2009208521A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of freely setting ackerman ratio while maintaining high steering rigidity. <P>SOLUTION: A left rack shaft 1 connected to a left wheel and a right rack shaft 2 connected to a right wheel are opposedly arranged in a vehicle longitudinal direction, a first left turning rack 6 and a first right turning rack 7 with different rack pitch from each other are provided on the left rack shaft 1, and a second left turning rack 8 and a right turning rack 9 with different rack pitch from each other are provided on the right rack shaft 2. On the steering shaft 10, a first pinion 12 engaged with the first left turning rack 6 at left turning, a second pinion 13 engaged with the left turning rack 8 at left turning and engaged with the first right turning rack 7 at right turning, and a third pinion 14 engaged with the second right turning rack 9 at right turning are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field of a rack and pinion type vehicle steering apparatus.

Patent Document 1 discloses a technique for changing the Ackermann rate using a rack moving mechanism that displaces a rack shaft in the vehicle longitudinal direction.
Japanese Patent Laid-Open No. 2003-127876

  However, since the rack shaft is displaced in the vehicle front-rear direction in the above-described prior art, there is a problem that steering rigidity is low, and steering stability is deteriorated and steering stability such as course holding performance is deteriorated. It was.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle steering apparatus capable of freely setting an Ackermann rate while maintaining high steering rigidity. .

  In order to achieve the above object, in the present invention, a left steering rack and a right steering rack having different rack pitches are formed on the left and right rack shafts, respectively, and a pinion connected to the steering shaft is provided. , Two left-turning pinions that mesh with the left-hand turning racks on the left and right rack shafts when turning left, and two right-turning gears that mesh with the right-turning racks on the left and right rack shafts when turning right It consisted of a pinion.

  According to the present invention, it is possible to freely set the Ackermann rate while maintaining high steering rigidity.

  Hereinafter, the best mode for carrying out the present invention will be described based on Examples 1 and 2.

  FIG. 1 is a plan view showing the configuration of the vehicle steering device of the first embodiment, and FIG. 2 is a left side view showing the configuration of the vehicle steering device of the first embodiment. 1 and 2 both show a neutral state in which the steering is neutral. In the following description, left and right indicate left and right on the plan view of FIG.

  The vehicle steering apparatus according to the first embodiment includes a left rack shaft 1 and a right rack shaft 2. A left side rod 3 is connected to the left end of the left rack shaft 1. A left wheel (not shown) is connected to the left side rod 3. A right side rod 4 is connected to the right end of the right rack shaft 2. A right wheel (not shown) is connected to the right side rod 4.

  The left and right rack shafts 1 and 2 are housed in the rack casing 5 with the conventional rack shaft divided into two in the vehicle front-rear direction and overlapped in the vehicle front-rear direction. The left and right rack shafts 1 and 2 can slide in the vehicle width direction within the rack casing 5 without interfering with each other.

  In the rack casing 5, the left rack shaft 1 is located on the front side in the vehicle front-rear direction, and the right rack shaft 2 is located on the rear side in the vehicle front-rear direction. The lengthwise dimensions of the left and right rack shafts 1 and 2 are the same as the conventional product, and the widthwise dimension is about half that of the conventional product. Therefore, the outer shape and the internal space of the rack casing 5 are the same as the conventional product.

  On the left rack shaft 1, a portion where a rack is formed and a portion where there is no rack are arranged diagonally. That is, the first left steering rack 6 is provided on the left side of the left rack shaft 1 from the center position (II) in the vehicle width direction, and the first right steering rack 7 is provided on the right side from the center position (II) in the vehicle width direction. Is provided. The first left steering rack 6 and the first right steering rack 7 are arranged on the vehicle front side with respect to the first right steering rack 7. The rack pitch of the first left steering rack 6 is set larger than the rack pitch of the first right steering rack 7.

  On the right rack shaft 2, a portion where a rack is formed and a portion where there is no rack are arranged diagonally. That is, the second left steering rack 8 is provided on the left side of the center position (II) in the vehicle width direction of the right rack shaft 2, and the second right steering rack 9 is provided on the right side of the center position (II) in the vehicle width direction. Is provided. The second left steering rack 8 is disposed on the vehicle front side with respect to the second right steering rack 9.

  The rack pitch of the second right steering rack 9 is set to be larger than the rack pitch of the second left steering rack 8. The rack pitch of the second left steering rack 8 is the same as the rack pitch of the first right steering rack 7 of the left rack shaft 1, and the rack pitch of the second right steering rack 9 is the same as that of the left rack shaft 1. This is the same as the rack pitch of the first left-turning rack 6.

  The steering shaft 10 has a handle (not shown) connected to one end thereof and is accommodated in the steering case 11 so as to be rotatable around a rotation shaft (L-L). A first pinion 12, a second pinion 13, and a third pinion 14 are connected to the other end of the steering shaft 10 in this order from the tip side. The first pinion 12 meshes with the first left-turning rack 6 during left-turning. The second pinion 13 meshes with the second left steering rack 8 during left steering, and meshes with the first right steering rack 7 during right steering. The third pinion 14 meshes with the second right turning rack 9 at the time of right turning. As shown in FIG. 3, the vehicle width direction position of the rotation shaft (L-L) of the steering shaft 10 coincides with the vehicle width direction center position (I-I) of the left and right rack shafts 1, 2.

In the first embodiment, the racks 6 to 9 and the pinions 12 to 14 are straight tooth racks and straight tooth pinions, and the rack casings are configured such that each pinion 12 to 14 meshes with the corresponding rack at an angle of 90 degrees. The angle of the steering case 11 with respect to 5 is set.
The first pinion 12 and the third pinion 14 use pinions having the same shape, and have a larger diameter than the diameter of the second pinion 13. Therefore, as shown in FIG. 2, the first pinion 12 and the third pinion 14 are in a state in which the first right turning rack 7 and the second left turning rack 8 are sandwiched in the vehicle front-rear direction.
The axial dimensions from the first pinion 12 to the third pinion 14 are the same size as the conventional pinion.

A spring retainer 15 that presses the left and right rack shafts 1 and 2 against the steering shaft 10 is provided on the rear surfaces of the left and right rack shafts 1 and 2 (the surface opposite to the surface on which the racks 6 to 9 are provided). In the first embodiment, the rack and the pinion that are engaged at the time of the right turning and the left turning are different from each other. Therefore, in order to reliably maintain the engagement, the left and right rack shafts 1 and 2 by the spring retainer 15 The pressing is particularly effective.
Seal members 16 and 17 are interposed between the spring retainer 15 and the left and right rack shafts 1 and 2 to suppress an increase in sliding resistance of the left and right rack shafts 1 and 2 due to the pressing force of the spring retainer 15. . In the first embodiment, the seal members 16 and 17 are fixed to the left and right rack shafts 1 and 2, but may be fixed to the spring retainer 15 side.

  Guide grooves 18 and 19 are formed in the vehicle width direction on the vehicle front surface 1 a of the left rack shaft 1 and the vehicle rear surface 2 b of the right rack shaft 2. On the other hand, the rack casing 5 is provided with six guide protrusions 20a, 20b, 20c, 20d, 20e, and 20f that slide-engage with the guide grooves 18 and 19. Each of the guide protrusions 20a to 20f is formed in a circular shape at the tip, and is supported in rolling contact with the guide grooves 18 and 19 by being supported by the rack casing 5 so as to be rotatable in the left-right direction.

  Further, six roller members 21a and 21b that maintain the distance between the left and right rack shafts 1 and 2 in the vehicle front-rear direction by rolling contact with the vehicle front surface 2a of the right rack shaft 2 on the vehicle rear surface 1b of the left rack shaft 1. , 21c, 21d, 21e, 21f.

Next, the operation will be described.
[Steering operation]
In the vehicle steering apparatus according to the first embodiment, when the driver starts turning right from the neutral state of FIG. 4A, the first to third pinions 12 to 14 connected to the tip of the steering shaft 10 are rotated to the right. To do.
At this time, the second pinion 13 meshes with the first right steering rack 7 of the left rack shaft 1, and the third pinion 14 meshes with the second right steering rack 9 of the right rack shaft 2.

  Here, since the gear ratio between the second right-turning rack 9 and the third pinion 14 is set larger than the gear ratio between the first right-turning rack 7 and the second pinion 13, the left and right gear ratios are set. Thus, the right rack shaft 2 has a larger stroke (amount of movement in the axial direction) than the left rack shaft 1, and the tire turning angle difference between the inner and outer wheels can be increased. That is, it is possible to increase the Ackermann rate, and it is possible to reduce the turning radius when turning right.

  FIG. 4 (c) shows the case of left turning. At this time, the first pinion 12 is engaged with the first left turning rack 6 of the left rack shaft 1, and the second left turning of the right rack shaft 2. The second rackion 8 meshes with the second pinion 13.

Here, since the gear ratio between the first left steering rack 6 and the first pinion 12 is set larger than the gear ratio between the second left steering rack 8 and the second pinion 13, the left and right gear ratios are set. Due to this difference, the left rack shaft 1 has a larger stroke than the right rack shaft 2, and the tire steering angle difference between the inner and outer wheels can be increased. Therefore, it is possible to increase the Ackermann rate, and it is possible to reduce the turning radius when turning left.
[Cooperation between link efficiency and Ackermann rate]
Usually, when the attachment position of the tie rod and the knuckle arm is determined with priority given to securing link efficiency, the Ackermann rate cannot be secured. The link efficiency can be adjusted according to the suspension geometry. However, since the layout is limited, the link efficiency cannot be increased as a result, and a high-power actuator is required for the power steering system.

On the other hand, in Example 1, the combination of the left and right rack shafts 1 and 2 divided into two for left wheel steering and for right wheel steering, and a three-row pinion (first pinion 12 to third pinion 14), The rack and pinion meshes that differ between the right and left steering from the center are arranged so that the left and right tire turning angles can be arbitrarily changed.
For this reason, the Ackermann rate can be set freely even in a geometry arrangement that prioritizes link efficiency.

In the first embodiment, the gear ratio of the turning inner wheel is made larger than the gear ratio of the turning outer wheel, thereby realizing both improvement in link efficiency and securing of the Ackermann ratio.
As shown in FIG. 5, in the conventional vehicle steering apparatus, the link efficiency and the Ackermann rate are almost in a trade-off relationship, whereas in the first embodiment, both the high link efficiency and the high Ackermann rate are realized. is doing. This makes it possible to reduce the decrease in the Ackermann rate by 40% or more compared to the conventional configuration that emphasizes link efficiency.

[Maintenance of steering rigidity]
In the technique described in Japanese Patent Application Laid-Open No. 2003-127876, the left and right rack positions are changed while the left and right members are expanded. For this reason, the link is not fixed, and there is a large amount of play between the components, leading to a reduction in steering rigidity.

  On the other hand, in the vehicle steering apparatus of the first embodiment, the left and right rack shafts 1 and 2 are moved only in the length direction (axial direction), and need to be moved in the vehicle front-rear direction as in the prior art. There is no. Therefore, since the steering rigidity can be maintained as high as before, it is possible to improve both the steering feeling and the steering stability such as the course holding performance.

[Reduces overall size]
In the technique described in Japanese Patent Application Laid-Open No. 2003-127766, since the rack casing and the steering casing are moved in the vehicle front-rear direction by an L-shaped arm that moves up and down and a helical rack that moves the arm, the casing is It has a shape that is long in the vertical direction, is inferior in-vehicle property, and is difficult to apply to an actual vehicle.

  On the other hand, in the vehicle steering apparatus according to the first embodiment, the same type of casing as in the conventional case can be used, so that the size can be suppressed to the same level as in the conventional case. For this reason, it can be replaced with a vehicle steering device that is actually mounted on the vehicle, and is excellent in vehicle mounting.

[Right and left rack shaft positioning]
In the first embodiment, since the two left and right rack shafts 1 and 2 are caused to stroke in the rack casing 5, the left and right rack shafts 1 and 2 are connected to the pinions 12 to 14 as compared with the configuration using one rack shaft. And easily deviate from a predetermined position where they mesh properly.

  Therefore, in the first embodiment, the guide grooves 18 and 19 are formed on the left and right rack shafts 1 and 2, and the guide protrusions 20 a to 20 f that slide-engage with the guide grooves 18 and 19 are provided on the rack casing 5. Thereby, the moving direction of the left and right rack shafts 1 and 2 can be regulated in the stroke direction (vehicle width direction).

  In the first embodiment, the first pinion 12 and the third pinion 14 are set larger in diameter than the second pinion 13, and the first right steering rack 7 and the second pinion 14 are set by the first pinion 12 and the third pinion 14. The left steering rack 8 is sandwiched in the vehicle longitudinal direction. Therefore, both the movement of the left rack shaft 1 toward the vehicle front side and the movement of the right rack shaft 2 toward the vehicle rear side at the meshing positions with the respective pinions 12 to 14 can be restricted. Engagement between each rack 6-9 and each pinion 12-14 can be reliably maintained.

[Contact prevention of left and right rack shafts]
In the first embodiment, six roller members 21a to 21f are provided on the vehicle rear surface 1b of the left rack shaft 1 and are in rolling contact with the vehicle front surface 2a of the right rack shaft 2, so The distance between the front and rear directions can be maintained at a predetermined distance according to the amount of protrusion of each of the roller members 21a to 21f from the vehicle rear surface 1b. Thereby, the contact of both rack shafts 1 and 2 can be avoided, and the increase in sliding resistance can be prevented.

Next, the effect will be described.
The vehicle steering apparatus according to the first embodiment has the following effects.

  (1) A first left steering rack in which a left rack shaft 1 connected to the left wheel and a right rack shaft 2 connected to the right wheel are arranged opposite to each other in the vehicle front-rear direction, and the left rack shaft 1 has a different rack pitch. 6 and the first right-turning rack 7 are provided, the right rack shaft 2 is provided with a second left-turning rack 8 and a right-turning rack 9 having different rack pitches, and the steering shaft 10 is turned to the left A first pinion 12 that meshes with the first left steering rack 6 during steering, a second pinion that meshes with the second left steering rack 8 during left steering, and meshes with the first right steering rack 7 during right steering 13 and a third pinion 14 that meshes with the second right-turning rack 9 when turning right. As a result, the Ackermann rate can be set freely while maintaining high steering rigidity.

  (2) The pitch of the first left steering rack 6 of the left rack shaft 1 is set larger than the pitch of the first right steering rack 7, and the pitch of the second right steering rack 9 of the right rack shaft 2 is set. Is set larger than the pitch of the second left-turning rack 8. Thereby, the Ackermann rate can be increased and the turning radius of the vehicle can be reduced.

  (3) Since the first right-turning rack 7 and the second left-turning rack 8 are adjacent to each other in the vehicle front-rear direction and the pinions that mesh with both racks 7, 8 are one second pinion 13, both racks 7 , 8 can be reduced as compared with the case where a pinion that meshes with each other is provided separately.

  (4) Since the diameters of the first pinion 12 and the third pinion 14 are larger than the diameter of the second pinion 13, the left and right rack shafts 1 and 2 are sandwiched between the pinions 12 and 14 in the vehicle front-rear direction. Thus, the left and right racks 1 and 2 can be prevented from being separated, and the meshing between the racks 6 to 9 and the pinions 12 to 14 can be maintained.

  (5) Since the left and right rack shafts 1 and 2 are provided with the guide grooves 18 and 19 extending in the vehicle width direction, and the rack casing 5 is provided with the guide protrusions 20a to 20f that are slidably engaged with the guide grooves 18 and 19, the left and right rack shaft 1 , 2 can be regulated in the sliding direction.

  (6) Since the left rack shaft 1 is provided with the roller members 21a to 21f which are in rolling contact with the right rack shaft 2 and maintain the distance between the left and right rack shafts 1 and 2 in the vehicle front-rear direction, the contact between the left and right rack shafts 1 and 2 It is possible to prevent an increase in sliding resistance associated with.

Example 2 is an example in which each rack and each pinion is a helical tooth.
FIG. 6 is a left side view illustrating the configuration of the vehicle steering apparatus according to the second embodiment. In the second embodiment, the first left turning rack 31, the first right turning rack 32, and the second left turning are illustrated. The rack 33 and the second right steering rack 34 are helical racks, and the first pinion 35, the second pinion 36, and the third pinion 37 are helical pinions.

  The second pinion 36 has an inclination angle opposite to that of the first tooth portion 36 a that meshes with the first right-turning rack 32 and the second tooth portion 36 b that meshes with the first left-turning rack 33.

The inclination angle of the helical teeth is set so that the axial thrust generated by the engagement of the first left-turning rack 31 and the first pinion 35 is generated toward the rear side of the vehicle.
The inclination angle of the helical teeth is set so that the axial thrust generated by the engagement between the first right-turning rack 32 and the first tooth portion 36a of the second pinion 36 is generated toward the vehicle rear side.

The inclination angle of the helical teeth is set so that the axial thrust generated by the engagement between the second left-turning rack 33 and the second tooth portion 36b of the second pinion 36 is generated toward the front side of the vehicle.
The inclination angle of the helical teeth is set so that the axial thrust generated by the engagement between the second right-turning rack 34 and the third pinion 37 is generated toward the front side of the vehicle.
Since other configurations are the same as those in the first embodiment, illustration and description thereof are omitted.

Next, the operation will be described.
[Positioning action by axial thrust]
At the time of right turning, the first right turning rack 32 of the left rack shaft 1 is engaged with the first tooth portion 36a of the second pinion 36, and the second right turning rack 34 of the right rack shaft 2 is The third pinion 37 is engaged. At this time, an axial thrust force to the rear of the vehicle due to the engagement of the first right-turning rack 32 and the first tooth portion 36a acts on the left rack shaft 1. On the other hand, an axial thrust force forward of the vehicle due to the engagement of the second right-turning rack 34 and the third pinion 37 acts on the right rack shaft 2.

  Therefore, since the left and right rack shafts 1 and 2 are pressed toward each other when turning right, it is possible to prevent the left and right rack shafts 1 and 2 from being separated in the vehicle front-rear direction. Further, the relative displacement between the corresponding rack and pinion is suppressed, and the meshing state can be maintained.

  During left turning, the first pinion 35 is engaged with the first left turning rack 31 of the left rack shaft 1, and the second pinion 36 of the second pinion 36 is engaged with the second left turning rack 33 of the right rack shaft 2. The two tooth portions 36b mesh with each other. At this time, an axial thrust force to the rear of the vehicle due to the engagement of the first left steering rack 31 and the first pinion 35 acts on the left rack shaft 1. On the other hand, axial thrust to the front of the vehicle due to the meshing of the second left-turning rack 33 and the second tooth portion 36b acts on the right rack shaft 2.

  Therefore, since the left and right rack shafts 1 and 2 are pressed toward each other when turning left, it is possible to prevent the left and right rack shafts 1 and 2 from being separated in the vehicle front-rear direction. Further, the meshing state in which the relative displacement between the corresponding rack and pinion is suppressed can be maintained.

Next, the effect will be described.
In addition to the effects (1) to (6) of the first embodiment, the vehicle steering apparatus of the second embodiment has the following effects.

  (7) Each rack 31 to 34 and each pinion 35 to 37 is a helical rack and a helical pinion, and each of the racks 31 to 34 and the pinions 35 to 37 are arranged so that axial thrust is generated in the direction in which the left and right rack shafts 1 and 2 approach each other during turning. The inclination angle of the tooth was set. As a result, it is possible to both prevent the left and right rack shafts 1 and 2 from being separated and maintain the meshing between the rack and the pinion.

(Other examples)
As mentioned above, although the best form which implements the vehicle steering device of this invention was demonstrated based on Example 1, 2, the concrete structure of this invention is not limited to Example 1,2. Any design changes that do not change the gist of the invention are also included in the present invention.

  For example, in the first and second embodiments, the second left-hand turning rack 8 of the right rack shaft 2 meshes with the second left-turning rack 8 during left-turning, and the second right-hand turning rack 7 of the left rack shaft 1 meshes with the second right-turning rack 7 during right-turning. Although an example in which the pinion 13 is provided is shown, a pinion that meshes with the second left turning rack 8 of the right rack shaft 2 at the time of left turning, and a first right turning rack 7 of the left rack shaft 1 at the time of right turning. A pinion that meshes with each other may be provided separately.

1 is a plan view illustrating a configuration of a vehicle steering apparatus according to a first embodiment. 1 is a left side view illustrating a configuration of a vehicle steering device according to a first embodiment. 1 is a front view illustrating a configuration of a vehicle steering apparatus according to a first embodiment. It is explanatory drawing which shows the steering operation of the steering apparatus for vehicles of Example 1. FIG. It is a relationship diagram of the link efficiency and the Ackermann rate which show the effect | action of Example 1. FIG. It is a left view which shows the structure of the steering apparatus for vehicles of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Left rack shaft 1a Vehicle front surface 1b Vehicle rear surface 2 Right rack shaft 2a Vehicle front surface 2b Vehicle rear surface 3 Left side rod 4 Right side rod 5 Rack casing 6 First left steering rack 7 First right steering Rack 8 Second left steering rack 9 Second right steering rack 10 Steering shaft 11 Steering case 12 First pinion 13 Second pinion 14 Third pinion 15 Spring retainers 16, 17 Seal members 18, 19 Guide grooves 20a to 20a 20f Guide protrusions 21a to 21f Roller member 31 First left turning rack 32 First right turning rack 33 Second left turning rack 34 Second right turning rack 35 First pinion 36 Second pinion 36a First 1 tooth part 36b 2nd tooth part 37 3rd pinion

Claims (7)

In a vehicle steering apparatus comprising a pinion connected to a steering shaft, and a rack shaft having a rack meshing with the pinion and slidable in the vehicle width direction,
The rack shaft includes a left rack shaft coupled to a left wheel, a right rack shaft disposed on the front or rear side in the vehicle front-rear direction with respect to the left rack shaft, and coupled to a right wheel,
The left and right rack shafts are each formed with a left steering rack and a right steering rack with different rack pitches,
The left pinion engages with the left steering racks of the left and right rack shafts when turning left, and the left steering pinion of the left and right rack shafts engages with the left steering racks when turning right. A vehicle steering system comprising two right-turning pinions. The vehicle steering apparatus according to claim 1,
The left steering rack pitch of the left rack shaft is set larger than the right steering rack pitch, and the right steering rack pitch of the right rack shaft is set larger than the left steering rack pitch. A vehicle steering system characterized by that. The vehicle steering apparatus according to claim 1 or 2,
The left steering rack and the other right steering rack of the left and right rack shafts are adjacent to each other in the vehicle longitudinal direction,
A steering apparatus for a vehicle, wherein a left steering pinion that meshes with the one left steering rack and a right steering pinion that meshes with the other right steering rack are integrally formed. The vehicle steering apparatus according to claim 3,
A steering apparatus for a vehicle, wherein a diameter of a pinion positioned at the foremost and last position in the vehicle front-rear direction among the pinions is set to be larger than that of other pinions. The vehicle steering apparatus according to any one of claims 1 to 4, wherein:
One of the casing for housing the left and right rack shafts and one of the left and right rack shafts is provided with a guide groove extending in the vehicle width direction, and the other is provided with a guide protrusion that slide-engages with the guide groove. apparatus. The vehicle steering apparatus according to any one of claims 1 to 5,
2. A vehicle steering apparatus according to claim 1, wherein at least one of the left and right rack shafts is provided with a roller member that is in rolling contact with the other rack shaft to maintain a distance between the two rack shafts in the vehicle front-rear direction. The vehicle steering apparatus according to any one of claims 1 to 6, wherein:
Each rack and each pinion is a helical rack and a helical pinion,
The axial thrust direction due to meshing between the two left-turning racks and the two left-turning pinions and the axial thrust direction due to the meshing between the two right-turning racks and the two right-turning pinions The vehicle steering apparatus characterized in that the left and right rack shafts are set in a direction approaching the vehicle longitudinal direction.

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