JPH0239901Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a four-wheel steering device that can also steer the rear wheels in accordance with the steering of the front wheels.

(Prior art) Conventional four-wheeled vehicles are typically steered by steering only the front wheels using a steering wheel, but steering only the front wheels may cause the rear wheels to skid depending on the driving situation. Problems have been pointed out in terms of maneuverability and driving performance, such as the limited turning radius and the inability to make small turns.In view of this, a four-wheel steering system that steers both the front wheels and the rear wheels has recently been proposed and researched. ing.

In other words, with a four-wheel steering system, if the rear wheels are steered in the same direction as the front wheels when driving at relatively high speeds, lateral force is applied to the front and rear wheels at the same time, so the phase shift from the steered wheels is There is no lag, and the vehicle's attitude can be maintained almost on the tangent to the turning circle, making it possible to smoothly change lanes when driving at high speeds, for example. Also, if the rear wheels are steered in the opposite direction to the front wheels when driving at very low speeds, the direction of the vehicle can be changed significantly, which is convenient for parallel parking or parking in a garage.

Furthermore, considering that the front wheels are not steered significantly at relatively high speeds, and the front wheels are steered significantly when driving at relatively low speeds, the rear wheels are also steered within the range where the front wheels are steered small. steer in the same direction,
When making a large turn, steer the rear wheels in the opposite direction 4
It can be seen that a wheel steering device is required.

The four-wheel steering device as described above can be realized in principle using various methods, and various specific configurations have been proposed.
No. 20565, JP-A-58-122257, and JP-A No. 122259, a known rack-binion type steering device that steers the front wheels in accordance with the operation of the steering wheel is provided with a rack that meshes with the rack. There is a vehicle in which a second pinion is provided, and the rotation of the second pinion is transmitted to the steering means for the rear wheels via a transmission shaft.

However, in this case, since two pinions are provided on one rack, there is a limit to the placement position of the second pinion. In other words, since the position of the steering wheel cannot be changed, the position of the first pinion connected to the steering wheel can hardly be changed.Furthermore, if a power steering device is installed, a power cylinder must also be installed on the rack, so the position of the second pinion cannot be changed. is even more restricted.

Therefore, as a structure for extracting the steering amount of the front wheels and transmitting it to the rear wheel steering device, a rack member such as the above-mentioned rack is provided approximately parallel to the operating member of the front wheel steering device, and these operating members and the rack member are connected via a connecting member. It is conceivable that the rack members be fixed to each other, and that the rack members can be moved laterally and laterally together with the actuating member. That is, the lateral movement of the operating member is transmitted to a rack member provided offset from the operating member, and the amount of steering of the front wheels is taken out via this rack member and transmitted to the rear wheel steering device. It is possible to do so. By doing so, the arrangement position of the transmission member that takes out the amount of steering of the front wheels and transmits it to the rear wheel steering device is not restricted by the operating member, and the degree of freedom is improved.

However, with such a configuration, a load during steering or an external load input from the rear wheels via the rear wheel steering device and the transmission member acts on the connecting member, etc. In order to prevent the connecting member from deforming, it is necessary to make the connecting member strong, which places significant restrictions on the layout around the front wheels.

(Purpose of the invention) The present invention was made in view of the above circumstances, and after solving the problem of improving the degree of freedom in the arrangement position of the transmission member, it also solves the problem of new problems that arise from solving this problem. It is an object of the present invention to provide a four-wheel steering system for a vehicle that can reduce the load on connecting members and the like.

(Structure of the invention) The four-wheel steering system for a vehicle according to the invention is provided by providing a rack member substantially parallel to the operating member via a connecting member as described above, and by providing a power steering device to the rear wheel steering device. , which aims to achieve the above purpose.

In other words, in a four-wheel steering system for a vehicle that steers the rear wheels as the front wheels are steered, the steering wheel is located between the left and right front wheels at a position close to the body panel that partitions the passenger compartment and the engine room, and which connects the left and right front wheels. An actuating member of a front wheel steering device that is provided across the body and can be moved left and right by operating a steering wheel; a connecting member having one end fixed to the actuating member so as to be substantially perpendicular to the actuating member; and this connecting member. a rack member fixed to the other end, provided so as to be able to move horizontally together with the actuating member via the connecting member, and provided substantially parallel to the actuating member; and a transmission member that converts the lateral movement of the member into rotation and transmits the steering amount of the front wheels to the rear wheel steering device, and the rear wheel steering device is provided with a power steering device consisting of a power cylinder and a control valve. It is characterized by being

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 are a plan view and a front view showing an example of the four-wheel steering system of the present invention, in which the direction of arrow F indicates the front of the vehicle. steering wheel 1
When the steering wheel is operated, this rotation is transmitted to the first gearbox 2 via the steering shaft 1a, and in the first gearbox 2, the rotation is converted into movement in the width direction of the vehicle body by a known mechanism such as a rack and pinion mechanism. The first rack (main rack, corresponding to the actuating member) provided in the first rack housing 3 is moved in the width direction of the vehicle body. Since both ends of this first rack are connected to the right and left tie rods 4a and 4b, the movement of the first rack in the width direction of the vehicle body connects the tie rods 4a and 4b.
The front wheels are steered by moving the knuckle arms connected to the tie rods 4a and 4b via the knuckles to steer the front wheels 5a rotatably supported by the knuckles. The first rack above is as shown in the figure.
It is arranged in the vehicle width direction so as to connect the left and right front wheels at a position close to the vehicle body panel that partitions the vehicle interior and the engine room. A power cylinder is formed within the first rack housing 3, and a piston fixed to the first rack is fitted into the power cylinder. Pressure oil from a hydraulic pump (not shown) is sent into this power cylinder in response to the operation of the steering wheel 1 via a front wheel control valve provided in the gearbox 2, and the piston receives this oil pressure to drive the first rack. The movement is power assisted. That is, the known front wheel power steering device is configured as described above. Note that the first rack housing 3 is fixed to a bracket 11a of the vehicle body 11, and the front wheel power steering device is attached to the vehicle body.

Further, a second rack housing 7 is fixed to the first rack housing 3, and a second rack (corresponding to a rack member in the claims) is disposed within the second rack housing 7 in parallel with the first rack. It is arranged so that it can be moved in any direction. This first rack and the second
The racks are connected by a connecting arm 6 (corresponding to the connecting member), and when the first rack is moved in the width direction of the vehicle body by operating the steering wheel 1, the second rack also moves together. When the second rack moves, a second pinion (corresponding to a part of the transmission member) meshes with the second rack in a second gearbox 8 fixed to the second rack housing 7.
is rotated. A take-out shaft 8a that protrudes rearward from the second gearbox 8 is coupled to the second pinion, and this take-out shaft 8a is connected to a first U joint 9, a front transmission shaft 10, and a second U joint arranged in the vehicle body tunnel portion 11b.
It is connected to the input shaft 52 of the mechanical control box 50 via the joint 13, and the second
Rotation of the pinion is transmitted to this input shaft 52.
These members 8a, 9, 10, 13, and 52, together with the second pinion, correspond to the transmission member.
The rotation of the input shaft 52 is appropriately converted by the mechanical control box 50 and output as the rotation of the output shaft 53, as will be described later. Output shaft 5
3 rotation is the first coupling 14 and the rear transmission shaft 15
and is transmitted via the second coupling ring 16 to the intake shaft 17a, which is connected to a third pinion disposed in the third gearbox 17.

The third gearbox 17 is fixed to a third rack housing 18, and the third rack housing 18 is fixed to a subframe 21. A third rack is disposed within the third rack housing 18 and is movable in the width direction of the vehicle body and has both ends connected to the tie rods 19, and this third rack meshes with the third pinion. Therefore, the rotation of the third pinion moves the third rack in the width direction of the vehicle body, and this movement is transmitted to the knuckle arm via the tie rod 19, so that the rear wheel 40 rotatably supported by the knuckle arm is steered. A power cylinder is also formed within the third rack housing 18, and a piston fixed to the third rack is fitted into the power cylinder. Pressure oil from the line 17c is fed into this power cylinder in accordance with the rotation of the intake shaft 17a via the rear wheel control valve 17b attached to the third gear box 17, and the piston receives this oil pressure and the third Ratsuku's movements are now power assisted. That is, the rear wheels are also steered by the power steering device, and the steering is done in accordance with the amount converted by the mechanical control box 50 from the amount of steering of the front wheels.

Next, the mechanical control box 50 will be explained using FIGS. 3 to 6.

In FIG. 3, an input shaft 52 and an output shaft 53 are rotatably supported below a box-shaped housing 51, and the free end of the input shaft 52 is connected to the fitting portion 5 of the output shaft 53.
4 is fitted. A gear 55 is fixed to the input shaft 52 near one side wall of the housing 51, and a support flange member 56 is provided so as to be relatively rotatable. The gear 55 meshes with an idle gear 58 fixed to a rotating shaft 57, and this idle gear 58 meshes with a gear 6 on a rotating shaft 59 rotatably mounted above the housing 51.
It is engaged with 0. The flange member 56;
A flange portion 61 formed continuously on the output shaft 53
are interconnected by a cylindrical member 62,
The output shaft 53, which includes the flange member 56, the cylindrical member 62, and the flange portion 61, is configured to rotate integrally. Two ribs 63.64 are formed on the outer peripheral surface of the intermediate portion of the cylindrical member 62, and as shown in FIGS. 4 and 5, each rib 63.64 has a rib 63. Bolts 65 and 66 are screwed together in opposite directions.

A pair of rotating members 67 and 68 are rotatably attached within the space defined by the flange member 56, the cylindrical member 62, and the flange portion 61. One rotating member 67 consists of a fitting part 69 fitted to the input shaft 52, a flange part 70, and a cylindrical part 71 extending in the axial direction from a part near the outer periphery of the flange part 70. It has a protrusion 72 on the top. The other rotating member 68 has a fitting part 76 fitted to the input shaft 52 and a flange part 7.
3 and a cylindrical portion 74 extending in the axial direction from a portion near the inner circumference of the flange portion 73.
It has a protrusion 75 on its outer periphery. Figures 4 and 5
As is clear from the figure, bolts 77 and 78 are screwed into the fitting portions 69 and 76 in opposite directions, respectively, and pins 79 and 8 inserted onto the input shaft 52
It is possible to make contact with 0. both flange parts 70,
A torsion spring 81 is disposed in a space defined by the cylindrical portion 73 and the cylindrical portions 71 and 74, and its both ends are locked to the flange portion 70 and the flange portion 73, respectively. This spring 81 biases the rotating member 67 in the clockwise rotation direction and the rotating member 68 in the left rotation direction with a predetermined set load, thereby urging the protrusions 72 and 68, respectively.
75 and pins 65 and 66 are normally in contact with each other.

A gear 82 is attached to the fitting portion 54 of the output shaft 53 so as to rotate integrally therewith.
It is meshed with a gear 84 fixed on a rotating shaft 83 rotatably attached to the housing 51 so as to face the rotating shaft 59 .

As shown in FIG. 6, the inner ends of the rotation shafts 59 and 83 have a pair of projections 85 and 86 spaced apart in the diametrical direction, and after the projections come into contact with each other, the rotation of the input shaft 52 is controlled by these projections. The signal is inverted and transmitted to the output shaft 53 via the shafts 59 and 83 of the same.

Next, the operation of this embodiment will be explained.

Assuming that the steering wheel 1 is now turned to the right, the front wheel control valve is controlled in accordance with the amount of steering (θ _H ), and the first and second racks are controlled by the action of pressure oil on the piston fixed to the first rack. The second rack moves to the left, steering the front wheels 5 to the right (θ _F ), and the input shaft 52 is rotated to the right through the engagement between the second rack and the second pinion.

When the input shaft 52 is rotated to the right, the rotating member 68 is rotated to the right through contact between the pin 80 and the bolt 78 shown in FIG. 77, the rotating member 67 rotates to the right integrally with the rotating member 68 via the spring 81.

In that case, the cylindrical member 63, i.e., the output shaft 53 is
will rotate to the right.

When the input shaft 52 turns to the right, the rotating shaft 59 also turns to the right via the gears 55, 58 and 60, but the front wheel 5
When the steering angle θ _{F of} Since there is an interval of , the rotation of the rotating shaft 59 is not transmitted to the rotating shaft 83. Therefore, rotational force is transmitted to the output shaft 53 via the two rotating members 67 and 68.

When the output shaft 53 turns to the right, the rear wheel control valve 17b is controlled, the third rack is moved to the left by the pressure oil, and the rear wheel 20 is steered to the right (θ _R ).
be done.

However, when the steering angle of the front wheel 5 to the right becomes θ ₁ or more, the protrusion 85 of the rotary shaft 59 and the protrusion 86 of the rotary shaft 83 come into contact with each other, and the movement of the input shaft 52 is controlled by these rotary shafts 59, 86, 83 etc.,
Further, the reversed force is transmitted to the output shaft 53 by gears 84 and 82. Then, the spring 81 has
A force in the left rotation direction is applied via the cylindrical member 62 and the rotating member 67, and a force in the right rotation direction is also applied via the rotation member 68. From the relationship between these two forces and the magnitude of the set load of the spring 81, the input shaft 52 rotates to the right together with the rotating member 68;
The output shaft 53 rotates to the left together with the cylindrical member 62 and the rotating member 67 while bending the spring 81. In this way, the control of the control valve section 17b is reversed,
The rear wheel 20, which has been steered to the right until now, begins to be steered to the left (in the opposite direction to θ _R ). Then, when the front wheels 5 are further steered to the right, the rear wheels 20 pass the neutral position and are steered to the left at the second predetermined steering angle θ ₂ .

When the steering wheel 1 is turned to the left from the neutral position, the operation is the same as above except that the operation is reversed.

Note that FIG. 7 shows the relationship between the steering wheel steering angle (θ _H ) and the rear wheel turning angle (θ _R ).

FIG. 8 is an enlarged view of the front wheel steering device of the embodiment shown in FIG. 1, and the same parts are designated by the same numbers. A first rack housing 3 that holds the first rack 3a movably in the width direction of the vehicle body.
is fixed to a bracket 11a of the vehicle body 11. The second rack 7a is parallel to the first rack 3a and connected to the first rack 3a by a connecting arm 6, and is held in the second rack housing 7 so as to be movable in the width direction of the vehicle body. In this embodiment, the first rack housing 3 and the second rack housing 7 are integrally formed. When the rack housings are integrated, the accuracy of the parallelism between the hole housing the first rack 3a and the hole housing the second rack 7a can be increased. The bond is strong and rigid, and it has the advantage of being less prone to twisting when a lateral impact is applied to the front wheels. However, since manufacturing is relatively difficult and the parts are not compatible with the two-wheel steered vehicle, it is conceivable to make both housings separate.

FIGS. 9 to 11 show an embodiment of the present invention in which both housings are separated. Fig. 9 is a front view of the front wheel steering device as seen from below the front of the vehicle body (viewed in the direction of arrow C in Fig. 10), and Fig. 10 is a cross section taken along arrow A-A in Fig. 9. 11 are side views seen in the direction of arrow B in FIG. 9. Note that in FIG. 9, the left part is partially omitted, and therefore the first gearbox 2 is not shown.

The first rack 3a, which can be moved left and right according to the operation of the steering wheel, is slidably arranged inside the first rack housing 30, and the first rack housing 30 is moved through a mount rubber 27 as shown in FIG. The mounting member 26 is fixed to the bracket 11a by tightening bolts 26a. A connecting arm 6 is fixed near the right end of the first rack 3a in the figure, and the tip 6a of the connecting arm 6 is fitted into a spherical bushing 7b attached to the right end of the second rack 7a. That is,
The first rack 3a and the second rack 7a are connected via a spherical bush 7b. The second rack 7a is arranged parallel to the first rack 3a and is slidably disposed within the second rack housing 20 in the width direction of the vehicle body. The second gearbox 8 is configured such that a second pinion and the like are housed in a space surrounded by a gear housing 21 integrally formed with the second rack housing 20 and a gear cover 8a.
a meshes with a second pinion 8b in the second gearbox 8, and the second pinion 8b is connected to a take-out shaft 8a that projects toward the rear of the vehicle body. In addition, the second
The rack 7a is biased toward the second pinion 8b via the plastic body 7c by a spring 7d to reduce play when the second rack 7a and second pinion 8b are engaged.

Further, the second rack housing 20 is integrally formed with a coupling flange 22 for coupling with the first rack housing 30, and the first rack housing 30 is disposed on the coupling flange 22 via a mount rubber 27. The flange cover 23 presses this down, and the first rack housing 3
0 and the second rack housing 20.
Furthermore, the coupling flange 22 and the mounting member 2
6 are bridged by an intermediate member 25 to connect the two, thereby supplementing the rigidity of the first rack housing 30.

As described above, when the first rack housing 30 and the second rack housing 20 are made separately, in addition to easy manufacture of both housings,
It can be used as a two-wheel steering device simply by removing the rack housing 20 and its accessory parts.

(Effects of the Invention) As explained in detail above, according to the present invention, the rear wheels are steered by the transmission member that is connected to the operating member of the steering device via the connecting member and meshes with the rack member arranged in parallel. Since the power is obtained, there is a large degree of freedom in the extraction position of the steering power of the rear wheels, and the above-mentioned transmission member that transmits the steering power from the front wheel side to the rear wheel side can be easily placed, for example, in the tunnel part of the car body. It is also easy to arrange. Further, since the rear wheel steering device is provided with a power steering device, the load input to the connecting member during steering may be large enough to operate the valve, and there is no risk of deforming the connecting member. In addition, since there is a control valve, the power steering always acts in a straight line even in response to external forces when the vehicle is not being steered.
No load is input to the connecting member. Therefore,
The connecting member can be made smaller and the amount of offset of the rack member from the actuating member can be reduced.

[Brief explanation of the drawing]

1 and 2 are a plan view and a front view showing an example of the four-wheel steering device of the present invention, FIG. 3 is a sectional view of a mechanical control box, and FIGS. 4, 5, and 6 are respectively Arrow in Figure 3 -
, - and -, Fig. 7 is a graph showing the relationship between the steering wheel steering angle and the rear wheel turning angle, and Fig. 8 is a plan view showing an example of the front wheel steering device having an integrated housing according to the present invention. 9 is a front view showing an example of a front wheel steering device having a separate housing according to the present invention, FIG. 10 is a sectional view taken along arrow A-A in FIG. 9, and FIG. 11 is a cross-sectional view taken along arrow B in FIG. 9. FIG. DESCRIPTION OF SYMBOLS 1... Steering wheel, 3, 30... 1st rack housing, 3a... 1st rack (operating member), 6... Connection arm (connection member), 7, 20
...Second rack housing, 7a...Second rack (rack member), 8...Second gearbox, 8a...
...Second pinion (part of the transmission member), 8b...Take-out shaft (part of the transmission member), 9, 13...U joint, 10, 15...Transmission shaft, 18...Third rack housing, 50 ...Mechanical control box.

Claims (1)

[Scope of claims for utility model registration] 4. Vehicles in which the rear wheels are steered as the front wheels are steered
In a wheel steering system, a front wheel that is located close to the vehicle body panel that partitions the passenger compartment and the engine compartment and extends between the left and right front wheels so as to connect the left and right front wheels, and that can be moved left and right by operating the steering wheel. an actuating member of a steering device; a connecting member having one end fixed to the actuating member so as to be substantially perpendicular to the actuating member; and a connecting member fixed to the other end of the connecting member and working with the actuating member through the connecting member. A rack member is provided to move left and right and is provided substantially parallel to the actuating member, and the rack member meshes with the rack member and converts the left and right movement of the rack member into rotation to cause the rear wheel steering device to steer the front wheels. A four-wheel steering system for a vehicle, comprising: a transmission member that transmits an amount of power, and the rear wheel steering system is provided with a power steering system that includes a power cylinder and a control valve.