JPS60185674A - Four-wheel steering unit for vehicle - Google Patents

Abstract

PURPOSE:To improve the stability in high speed running and the stability in control in low or medium speed running, by turning rear wheels by means of a rear wheel turning apparatus in accordance with steering in front wheels while enabling the turning of the rear wheels to be corrected by an auxiliary rear wheel turning means. CONSTITUTION:Steering in front wheels is mechanically transferred to rear wheels by means of a steering force transfer unit 30 and a rear wheel turning apparatus 20, and the rear wheels are turned in accordance with the steering in the front wheels. A suspension mount frame 14 is connected with both ends 42a and 42b of an auxiliary turning member 42 of the auxiliary rear wheel steering means 40. The auxiliary rear wheel turning means 40 is adapted such that the auxiliary turning member 42 is moved in the transverse direction through a rack and pinion in accordance with rotation of a step motor 44, and the movement of the member 42 is enhanced by a power cylinder applied with a hydraulic pressure from a second control valve 43. When the auxiliary turning member 42 is moved in the transverse direction, the suspension mount frame 14 is pushed, whereby rubber bushes 13a, 13b and 13c supporting the frame 14 are deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a 1c four-wheel steering device that steers both the front wheels and the rear wheels by steering the front wheels of an automobile.

(Prior art) Conventionally, most of the steering in automobiles was performed by steering only the front wheels, and the rear wheels were rotated in a V4-polar manner, even if there was some 1~-in or 1-1-out. There was nothing to steer.However, if you use a four-wheel steering device that steers the rear wheels in response to the steering of the front wheels, maneuverability and stability can be greatly improved.For example, When maneuvering a vehicle at extremely low speeds such as parking or garaging,
For the front wheel. By steering the rear wheels in the opposite direction (this is called anti-phasing), it is possible to greatly change the direction of the vehicle, making it possible to park in narrow spaces that were previously impossible or extremely difficult. Or it becomes easier. Further, in a U-turn, the minimum turning radius can be made small, which is advantageous. In general, steering the rear wheels in the opposite phase to the front wheels in this manner allows the difference between the inner wheels to be extremely reduced or eliminated, which is advantageous when turning a narrow corner. In addition, when steering a vehicle at such extreme speeds, steering the rear wheels in the same direction as the front wheels (this is called the same phase) makes it possible to cause the entire vehicle to move in parallel. , it is often convenient when parking or parking.

- On the other hand, when changing lanes while driving at medium to high speeds,
By performing four-wheel steering in the same phase, lateral force is applied to the front and rear wheels at the same time, making it possible to change lanes smoothly without phase lag. At this time, there is no yawing, so changing lanes at high speeds can be scary. It can be done without. Furthermore, when cornering, the direction of the vehicle can be effectively changed by steering the rear wheels in opposite phases.

In view of these circumstances, various four-wheel steering devices have recently been proposed. For example, there is a system in which steerable front wheels and rear wheels are connected by a link mechanism, and the rear wheels are steered in opposite phases in response to the steering of the front wheels (Japanese Patent Laid-Open No. 15301/1982);
A cam plate is moved according to the steering angle of the front wheels by a rond that cooperates with the curved wheel, and a bin fixed to the rear wheel steering member is held movably within the cam groove to steer both the front and rear wheels. A device that changes the steering angle ratio according to the steering angle JP-A-55-91
No. 458) etc. are known.

In this way, when the front and rear wheels are mechanically connected and the rear wheels are steered in response to front wheel steering, mechanical connection has the advantage of being reliable and responsive. , there is also the disadvantage that only one control characteristic can be obtained. For example, when the front wheel steering angle is small, the rear wheels are steered in the same phase because there are many cases such as lane changes, and when the front wheel steering angle is large, it is considered to be turning and the rear wheels are steered in the opposite phase. Although control such as steering the vehicle to improve its turning performance is possible using low-mechanical means, it is impossible to roughly correct this using vehicle speed or steering angular speed. Instead of doing this mechanically, the front wheel steering angle (θN) and vehicle speed (V) are detected electrically.
If a motor or hydraulic means is controlled based on this to steer the rear wheels, control based on multiple parameters is possible, but the reliability of electrical control systems is one step lower than that of mechanical systems. Reliability problems are likely to occur. In particular, the steering system is one of the most important components for vehicle driving safety and requires extremely high reliability.
Adopting an electrical control system is difficult.

(Object of the Invention) The present invention has been made in view of the above circumstances, and includes a main steering mechanism that mechanically transmits front wheel steering movement to a rear wheel steering device, and a main steering mechanism that mechanically transmits front wheel steering movement to a rear wheel steering device. The main steering mechanism 4f4 is supported by the vehicle body independently of the auxiliary steering mechanism, and the auxiliary steering Bi4S2 is also equipped with a sub-steering mechanism that utilizes electric power, hydraulic pressure, etc. It is an object of the present invention to provide a four-wheel steering system for a vehicle that can maintain the steering stability of the vehicle by using only MfC.

(Advanced Features of the Invention) The four-wheel steering device of the present invention mechanically transmits the steering force of the front wheels to the rear wheel steering device by a steering force transmission device, and steers the rear wheels in accordance with the front wheel steering. None, on the other hand, a rear wheel sub-wheel that applies hydraulic pressure to at least one of a plurality of support points of a suspension arm at which this rear wheel is supported by the vehicle body via an elastic body to deform the elastic body at this support point. This vehicle is characterized in that a steering means is attached to the vehicle body, and the amount of steering of the rear wheels can be corrected in accordance with the deformation of this elastic body.

(Effects of the Invention) According to the present invention, the rear wheels are steered by the rear wheel steering device in response to the steering of the front wheels, and the steering of the rear wheels can be corrected by the rear wheel auxiliary steering means. Maneuvering stability such as high-speed stability and low-to-medium speed retrospective performance can be greatly improved. In addition, the rear auxiliary steering means corrects the rear wheel steering by applying force to the vehicle body side support point of the suspension arm that supports the rear wheels and deforming the elastic body at this support point. Even if the vehicle loses its function, the rear wheels can still be supported without any problem, and the rear wheel steering device, which is mechanically activated in response to front wheel steering, ensures sufficient steering stability and is highly reliable and safe. ing.

〈Example The embodiments of the present invention will be described above with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of an automobile equipped with a four-wheel steering system according to the present invention. The steering device 1 includes a steering ring 3 that is steered by a driver, a first pinion 4 that converts the rotational power of the steering wheel 3 into reciprocating motion in the vehicle width direction, a first rank portion 5a of a rack member 5, and a base end. are connected to each end of the rack member 5.
and knuckle arms 7, 7, one end of which is connected to the tip of the tie rods 6, 6, and the other end of which is connected to the left and right front wheels 2L, 2R. 2R steering is performed.

Rear wheel 10L, one end of IOR is 1 eggplant mount frame 1
The suspension arm 11 is supported at the other end of the suspension arm 11, which is rotatably supported by the suspension arm 2, via knuckles 12, 12. Frame 14 goes to Zasu Mound 1 with rubber push 13 in 3 places
It is attached to the vehicle body via a, 13b, and 73G. A steering section 4422 of the rear wheel steering device 20 is connected to the arm portions of the knuckles 12, 12 that support the rear wheels 10L, 10R via tie rods, and movement of the steering member 22 in the vehicle width direction causes the knuckles to move. 12, 12 are rotated to perform rear wheel steering. The rear wheel steering device 20 has a rear transmission shaft 3S of the steering force transmission device 30 and a driver shaft 24,
A steering member 22 extending in the vehicle width direction and having a rack that meshes with a binion formed at the rear end of the input shaft 24, and a housing 21 that holds the steering member 22 slidably in the vehicle width direction. and a first controller 1 to a roll valve 23 that send hydraulic pressure to a power cylinder formed in this housing 21 according to the rotation of an input @ 24, and both ends of the steering section 22 are connected to left and right tie rods 15, 15, respectively. Connect with. Therefore, the steering member 22 is moved in the vehicle width direction within the housing 21 in accordance with the rotation of the entry J shaft 24 to perform rear wheel steering, and at the same time, pressure oil is supplied from the first control valve 23. In the power cylinder that receives this, hydraulic pressure is applied to a piston integrated with the steering part 22 inserted into the power cylinder, thereby assisting rear wheel steering.

The steering force transmission device 30 that transmits rotation to the input shaft 24 has a second vinyl Δ ring 31a at the front end that meshes with a second rack portion 5b formed on the rack member 5 of the front wheel steering device @1. The front transmission shaft 31 that extends quickly and this front transmission @b3
A mechanical control unit 1 to a roll box 32 is connected to the rear end of the mechanical control unit 1 to adjust the rotation of the front transmission shaft 31, and a roll box 32 is connected to the rear end of the mechanical control unit 1. ] It consists of a rear transmission shaft 33 that is connected to the shaft 24 and transmits the output of the Mechanino J Lucon 1 to the roll box 32 to the input shaft 24, and the movement of the rack part 5 due to front wheel steering is adjusted by the Mechanical Conn 1 to the roll box 32. It is placed in the input saw shaft 24 as a rotation.

Therefore, front wheel steering is mechanically transmitted to the rear wheels by the steering force transmission device 30J3 and the rear wheel steering device 20, and +i
& Rear wheel steering is performed in response to wheel steering.

Hereinafter, this rear wheel steering will be referred to as main steering.

On the other hand, both ends 42a and 42b of an auxiliary steering section 42 of a rear wheel auxiliary steering means 40 are connected to the suspension mount 1 to the frame 14. The rear wheel u1 steering means 40 includes the auxiliary steering member 42
, a housing 41 that supports this D1 steering member 42 so as to be slidable in the vehicle width direction, and a sub-steering member 42 within this housing.
a step motor 44 having a pinion on its rotating shaft that meshes with a rack formed in the housing; and a second control valve 43 that supplies hydraulic pressure to a power cylinder formed in the housing 41 in accordance with the rotation of the step motor 44. The auxiliary steering section 42 is moved in the vehicle width direction via the rack and pinion in accordance with the rotation of the step motor 44,
This action is assisted by a power cylinder that receives hydraulic pressure from the second control valve 43. When the sub-steering section 42 is moved in the vehicle width direction, the suspension mount frame 14 is pushed. The rubber pushers 13a, 13b, and 13c that support this are deformed.As shown in this figure, when the suspension mount frame 14 supported by 31 rubber pushes receives a force in the vehicle width direction from the auxiliary steering member 42, The rubber pushers 13a and 13b are deformed and rotated around the rubber pusher 13c.For this reason, the rear wheel 10
m, IOR is steered. Hereinafter, this rear wheel steering will be referred to as auxiliary steering. The rotation of the step motor 44 is controlled by a signal from the controller 54 that is input via a driver 55, and this signal is based on the vehicle speed signal J from the vehicle speed sensor 52.
j and the front wheel steering angle signal from the steering angle sensor 51. Note that the controllers 1 to 0 54 operate by receiving power supply from the battery 53.

The operation of the four-wheel steering system configured as described above will be explained below. Main steering angle (θRt) relative to front wheel steering angle (θH)
As shown in Fig. 2, when the front wheel steering angle (θH) is small, the main steering angle is increased in proportion to θH, that is, the rear wheels are steered to the same phase side, and when θH is a predetermined value, Value (θ/-771
), the mechanical control box 32 is configured to gradually make the steering smaller than θH, that is, to steer toward the opposite phase side. By using main steering in this way, since there are many lane changes in areas where the steering angle is small, in-phase steering enables smooth lateral movement, and in areas where the steering angle is large, anti-phase steering improves turning performance. It can be maneuvered well and maneuverability can be improved. On the other hand, as shown in Fig. 3, the secondary steering angle (θB2) changes in proportion to the front wheel steering angle <<θH), and this rate of change (i.e., the slope of the straight line) increases as the vehicle speed increases (Fig. (in the direction of the middle arrow A).

This is because steering in the same phase direction means that the rear wheels, which receive lateral force during turning, are steered toward the toe-in side.
The idea is to increase the secondary steering toward the toe-in side as the vehicle speed increases, thereby achieving both stability J5 at high speeds and retrospective performance at medium and low speeds.

Therefore, in this device that combines main steering and sub-steering,
The rear wheel steering angle (θR) is the fourth in relation to the front wheel steering angle (θH》).
The result will be as shown in the figure. Note that arrow A indicates the direction of change when the vehicle speed increases. Therefore, the advantages of both steering characteristics can be obtained, and the steering stability is greatly improved. Note that the sub-steering control is based on the front wheel steering angular velocity (θ) instead of the vehicle speed.
H) may be used to change the characteristics so that the slope of the straight line in Figure 2 decreases as dH increases,
This improves the ability to look back when making sharp turns.

Furthermore, since the auxiliary steering is performed by deforming the rubber pushers 13a, 13b, and 13c that support the suspension mount frame 14, even if the rear wheel auxiliary steering means 40 stops operating due to, for example, a failure in the control system, the main Since the steering is unaffected, sufficient steering stability can be ensured, and the main steering is done by highly reliable mechanical means.
This is a highly reliable and safe four-wheel steering device.

5 and 6 are a plan view and a front view showing a second embodiment of the four-wheel steering device of the present invention, and the arrow F
nt indicates the front of the vehicle. When the steering wheel 103 is operated by the driver, this rotation is transmitted to the first gear box 104.
In this first gearbox 104, the rack/binion Ia+! The rotation is converted into a movement in the width direction of the vehicle body by a known mechanism of I'8, and a first rack (not shown) provided in the first rack housing 105 is moved in the width direction of the vehicle body. Both ends of this first rack are connected to left and right tie rods 106, 106, respectively, and these left and right tie rods 106, 106 connect to left and right front wheels 102L, 102.
The first rack is connected to knuckle arms 107, 107 (both left side not shown) that hold R, and movement of the first rack in the width direction is transmitted to the knuckle arms 107, 107 to steer the front wheels. A power cylinder is formed in the first rack housing 105, and a piston fixed to the first rack is inserted into the power cylinder. A hydraulic bomb (not shown) is installed inside this power cylinder.
Pressure oil from the front wheel is sent through a front wheel control valve provided in the gear box 104 in response to the operation of the steering wheel 103, and the piston receives the hydraulic pressure generated in the power cylinder to power-assist the movement of the first rack. A known power steering device is configured as described above. Note that the first rack housing 105
is fixed to a bracket 111a of the vehicle body 111.

Below this first rack housing 105, there is a second rack disposed parallel to the first rack and movable in the vehicle width direction.
A second rack housing 109 is disposed inside with the second rack housing 109 shifted to the right, and this second rack housing 109 is fixed to the first rack housing 105. Further, the first rack and the second rack are connected to each other via the connecting rod 108, so that the movement of the first rack in the width direction in response to the operation of the steering ring 103 is directly transmitted to the second rack, and the second rack is directly connected to the second rack. The rack is also moved widthwise.

The second rack meshes with a second pinion within a second gear box 110 fixed to the second rack housing 109, and the second pinion is coupled with an output shaft 110a protruding rearward from the second gear A7 box 110. The movement of the second rack in the width direction is transmitted as rotation of the output shaft 110a.

This output shaft iioa is connected to an input shaft 114 of a mechanical control outlet box 113 via a first joint 112a, a front propeller shaft 112, and a second joint 112b.
The rotation of 0a is transmitted to the mechanical control box 113. Then, the rotation of the output shaft 114 is appropriately adjusted in the mechanical control box 113 (adjustment details will be described later) and output as rotation of the output shafts 1771 to 115. The output shaft 115 has a third joint 116a.
, rear propeller shaft 116, fourth joint 116b
A third gear disposed in the third gear box 117 via the
The rotation of the output shaft 115 is directly transmitted to the input shaft 117a since it is connected to the input shaft 117a which is connected to the pinion.

The third gear box 117 is a third rack housing 118
The third rack housing 118l is fixed to the subframe 120. A rear wheel steering member 119 that extends in the vehicle width direction and is movable in the vehicle width direction is disposed within the third rack housing 118 and has both ends protruding outward from the third rack housing 118 to the left and right.
A rack is formed at 9, and this rack meshes with the third pinion. Therefore, the third rotor is rotated by the rotation transmitted to the input shaft 117a, and the rear wheel steering member 119 is moved in the width direction accordingly. A power cylinder is also formed within the third rack housing 118, and a piston fixed to the rear wheel steering member 118 is fitted into the power cylinder to form left and right cylinder chambers. Pressure oil from a hydraulic pump (not shown) is supplied to these left and right cylinder chambers, and the G
Pressure oil is selectively fed through the rear wheel control valve 117b in accordance with the rotation of the input shaft 117a, and the piston receives the hydraulic pressure generated in the cylinder chamber and adjusts the width of the rear wheel steering member 119. The directional movement is depicted as being power assisted.

Both ends of the rear wheel steering section 119 are connected to the rear wheels 122m and 122R.
(122L is not shown) Knuckle arms 121, 12
1, and main steering is performed by left and right movement of the rear wheel steering member 119.

The rear wheels 122L and 122R are supported by the vehicle body via arms 124, but due to the left-right symmetry, only the right side of the vehicle body will be explained. The inner end of the arm 124 that rotatably supports the rear wheel 122R is rotatably fixed to the subframe 120, and is also supported by a sub arm 123 that extends roughly back and forth and has a front end connected to the vehicle body. The subframe 120 at the inner end of the arm 124 is connected to the subframe 12 as shown in the enlarged cross-sectional view (FIG. 7) taken along arrow B-B.
A first cylindrical rest 124a fixed to an arm 124 via a first rubber pusher 127 is rotatably connected around the bingo 20a fixed at zero. Furthermore, this first
A second rubber push 126 is arranged by recessing the cylindrical body 124a, and the second cylindrical body 12 surrounds the second rubber push 126.
5aIJ<It is rotatable with respect to the first cylindrical body 124a.

A sub-steering member 125 is joined to the second cylindrical body 125a,
This sub-steering member 125 is disposed within a power cylinder 131 fixedly installed within the sub-frame 20 so as to be slidable in the vehicle width direction. The auxiliary steering member 125 has a piston in the power cylinder 131, and when this piston receives pressure oil sent from the control valve 130 to the power cylinder 131, the auxiliary steering member 125 receives a force in the vehicle width direction. When the auxiliary steering section receives a force in the vehicle width direction, the arm 125 is also pushed and the first rubber pusher 127
Due to this deformation, the arm 125 is moved in the vehicle width direction relative to the subframe 120. Therefore, the shuttle wheel 122R is sub-steering around the connection point between the steering section 119 and the knuckle arm 121. The operation of the control valve 130 can be performed, for example, by a step motor or the like as in the first embodiment, so a description thereof will be omitted. In this way, in the second embodiment as well, the main steering is carried out mechanically and the secondary steering is carried out electrically, thereby further improving steering stability without impairing reliability. I can do it. It should be noted that the methods of main steering and sub-steering are the same as in the first embodiment, so their explanation will be omitted.

As explained above, in the present invention, a main steering system that includes a highly reliable mechanical operation system and an auxiliary steering system that can easily perform complex control are provided independently, thereby improving steering stability. It is possible to satisfy both improvement and reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first embodiment of an automobile having a four-wheel steering system according to the present invention; FIG. 2 is a graph showing the relationship between the main steering angle (θ1) and the front wheel steering angle (θ); Figure 3 is a graph showing the relationship between the front wheel steering angle (θ) and the auxiliary turning angle (θ2), Figure 4 is a graph showing the relationship between the front wheel steering angle (θ) and the rear wheel turning angle (θ), and Figure 5 6 are a plan view and a front view showing a second embodiment of an automobile having a four-wheel steering system according to the present invention. FIG. 7 is an enlarged sectional view showing the connecting portion between the subframe and the sub-steering member, taken along arrow B-8 in FIG. 5. FIG. 3, 103...Steering 5...Rack member 6,
106... Tie rod 7, 107... Knuckle arm 32, 113... Mechanical control opening box 22, 119... Steering member 42, 125... Sub-steering member -437-

Claims (1)

[Scope of Claims] A steering device for steering a curved wheel in a vehicle in which a rear wheel is supported by a suspension arm on a vehicle body at a plurality of support points via an elastic body, and a rear wheelset for steering a rear wheel. a steering stirrup; a steering force transmission device that mechanically connects both devices to transmit steering force from the front wheels to the rear wheels; A four-wheel steering system for a vehicle, characterized in that the rear wheel auxiliary steering means changes at least one deformation m.