JPS63173766A - Steering for vehicle - Google Patents

Abstract

PURPOSE:To secure the easiness of steering and safety in the high speed traveling by steering the front and rear wheels in an equal phase and varying the steering ratio between the front and rear wheels according to the car speed, in the high speed region, when a car travels at a high speed. CONSTITUTION:A straight line movement converted by a gear box 2 is transmitted to a differential gear 3 through an arm rod 2a, and divided into two kinds of displacement having different direction by a pinion 3c and racks 3a and 3b. The displacement of the left rack 3a of the differential gear 3 is constituted so as to steer front wheels 6 through a wheel connecting rod 5 from one edge of an arm rod 4. The other edge of the arm rod 4 is connected with a movable arm 8 which turns around a fulcrum 9 through a connecting rod 7. The displacement of the right rack 3b of the differential gear 3 turns rear wheels 14 through an arm rod 10, movable arm 11, and arm rods 12 and 13. The fulcrum 9 of the movable arm 8 can be shifted by the turn of a screw rod 16 by a motor 15. The motor 15 is controlled by a controller 19 by a car speed signal.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for steering a vehicle, particularly a four-wheeled vehicle.

(Prior Art) Steering in a four-wheeled vehicle is generally performed by steering only the front wheels. When a vehicle is running, when the front wheels begin to turn, a slip angle is first generated in the front wheels, which causes cornering force, lateral retardation of the vehicle body, and yawing around the center of gravity of the vehicle.

The rear wheels are the yaw of the vehicle! I! As a result of the movement, a slip angle occurs only after displacement in one direction begins to occur.

Therefore, the cornering force generated by the rear wheels has a phase lag compared to the front wheels, and there is always a slight time delay before the resultant force of the cornering forces of the front and rear wheels reaches the value intended by the driver. This causes the need for skill in steering the wheeled vehicle.

Furthermore, while a four-wheeled vehicle is making a turning motion by steering, side slip occurs in the wheels, so the tangent to the turning trajectory and the vehicle body axis do not always match, and in this respect, the four-wheeled vehicle There is a reason why the steering requires skill.

Therefore, the driver of a four-wheeled vehicle is required to perform steering by empirically recognizing the time delay in turning the rear wheels and the angle deviation between the turning trajectory and the vehicle axis in order to steer the four-wheeled vehicle appropriately. Driving a wheeled vehicle requires a certain amount of driving experience.

As a means to solve the above-mentioned problems with conventional steering devices, it has been proposed to steer the front wheels and the rear wheels. For example, Japanese Patent Publication No. 40-10728 discloses a method for giving the rear wheels a steering angle proportional to the sideslip angle of the rear wheels.
Further, US Pat. No. 2,910,131 discloses a method of controlling the amount of steering of the rear wheels by the lateral G of the vehicle body during turning.

(Problems to be Solved by the Invention) However, these known techniques not only have technical problems with the sideslip angle or G sensor that controls the steering of the rear wheels, but also both of them are caused by the steering of the front wheels. Since this method corrects the steering of the rear wheels based on factors, a response delay occurs in steering.

In addition, technology that steers both the front and rear wheels has been used in special vehicles, etc., but in both cases, the purpose is to reduce the turning radius and improve the maneuverability of the vehicle. This purpose is simply achieved by switching the control mode of the
56 specification, Japanese Patent Publication No. 53-26732).

Furthermore, JP-A-52-61024 discloses a method in which the rear wheels are steered in the opposite phase to the front wheels when driving at low speeds, but only the front wheels are steered without steering the rear wheels when driving at high speeds. However, this approach focuses only on the maneuverability of the vehicle, and does not improve the ease of steering or stability when driving at high speeds.

Therefore, an object of the present invention is to steer the rear wheels in the same phase as the front wheels at high speeds based on the vehicle speed, and to make the steering ratio between the front wheels and the rear wheels variable according to the vehicle speed. To provide a vehicle steering method which eliminates the delay in response of rear wheel steering due to follow-up correction, which is a drawback of conventional devices, and provides ease and stability of steering at high speeds. .

(Means for Solving the Problems) In order to solve the above problems and achieve the purpose, the present invention steers the front wheels by steering wheel operation, and steers the rear wheels in conjunction with the steering of the front wheels. In the vehicle steering method, when the speed of the vehicle is greater than a predetermined value, the front wheels and the rear wheels are steered in the same direction.

The steering ratio is set to a predetermined value according to the speed of the vehicle, and when the speed of the vehicle is detected, the VK wheels are set to the phase and rotation set with respect to the front wheels when the steering wheel is operated. It is characterized by steering with the rudder ratio.

(Function) The present invention steers the rear wheels in conjunction with steering of the front wheels by steering wheel operation, and when the vehicle is running at high speed, the front and rear wheels are steered in the same phase, and when the vehicle is running at high speed, the vehicle It changes the steering ratio of the front and rear wheels depending on the speed.

In other words, when steering at high speeds, the front and rear wheels are steered in the same phase, so even immediately after the start of steering, the front and rear wheels generate cornering force at the same time, and the lateral acceleration of the vehicle reaches the intended value in a short time. Steering responsiveness is greatly improved. Furthermore, as the vehicle speed decreases, the amount of steering angle of the rear wheels decreases, and the degree of improvement in response also decreases, but this does not pose a practical problem when the vehicle speed is low.

Next, the relationship between the direction of the vehicle and the turning trajectory according to the steering method according to the present invention will be explained based on a schematic diagram. If all the figures are shown with two wheels, or if the turning radius is sufficiently large compared to the wheel width, as is the case with a normal four-wheeled vehicle, there is no risk of impairing the validity of the explanation.

FIGS. 2 and 3 show the orientation and turning locus of a conventional vehicle that steers only its front wheels. When turning at extremely low speeds, the direction of movement of the vehicle coincides with the direction of the tires, so the direction of the vehicle faces outward from the tangent to the turning trajectory, as shown in FIG. As the vehicle speed increases, a slip angle occurs in the front and rear wheels, and the interlocking direction of the front and rear wheels points outward from the plane of the tires. Therefore, the turning center of the vehicle gradually moves forward, and the tangent to the turning locus begins to point outward with respect to the vehicle axis. That is, as shown in FIG. 3, the direction of the vehicle body is directed inward from the tangent to the turning trajectory.

In the case of the steering method of the present invention, when the vehicle speed is higher than a predetermined value and the vehicle is running at high speed, the front and rear wheels are steered in the same phase;
If the steering ratio of the front and rear wheels is determined in advance according to the vehicle speed so as to match the characteristics of the vehicle, the direction of the vehicle and the turning locus can be made to coincide as shown in FIG.

That is, at high speeds when the rear wheels are steered in the same phase as the front wheels, the steering ratio of the front and rear wheels is preferably controlled to approach +1 as the vehicle speed increases. By bringing the steering angle closer to the front wheel steering angle, the higher the speed, the more the straight line connecting the turning center and the center of the vehicle body will maintain a nearly right angle to the direction of the vehicle, which will almost eliminate rear wheel skidding. .

The above-mentioned high-speed in-phase steering of the front and rear wheels following the vehicle speed can be performed while the rear wheels are being steered in conjunction with the front wheels being steered by steering wheel operation.

(Example) Examples will be described below based on the accompanying drawings.

FIG. 1 shows a first embodiment of a steering device that can carry out the steering method of the present invention, and only the left wheel is shown, but the right wheel (not shown in the figure) is connected to the left wheel by a known method. connected to work together.

In FIG. 1, a known gear box 2 incorporating a rack-and-binion or the like for converting the rotational motion of the steered wheel l into reciprocating motion is disposed at the end of a shaft 1a extending from a steered wheel 1 forming a handle. . The linear motion converted by the gear box 2 is guided to the differential gear 3 by the arm rod 2a, and is transferred to the differential gear 3 by the arm rod 2a.
, the racks 3a and 3b are divided into two displacements in different directions. The displacement of the left rack 3a of the differential gear 3 is configured to steer the front wheels 6 from one end of the arm rod 4 via the connecting rod 5. The other end of the arm rod 4 is connected to a fulcrum 9 via a connecting rod 7.
It is connected to a movable arm 8 that rotates around .

On the other hand, the displacement of the right rack 3b of the differential gear 3 is the arm rod lO
A rear wheel 14 is steered by a movable arm 11 having a fulcrum at the center thereof, an arm rod 12, and an arm rod 13. The joint 18 of the arm rods 12 and 13 is fixed on the movable arm 8. The fulcrum 9 of the arm 8 moves on the screw rod 16 connected to the motor 15 and is fixed to the helical screw piece 17, so the fulcrum 9 is fixed on the movable arm 8. It is configured to move and hang on the arm 8 by rotation of a screw rod 16 by a motor 15. The motor 15 is controlled by a control device 19 which obtains a vehicle speed signal from a vehicle speed sensor 20 serving as vehicle speed detection means and controls the motor, and therefore the position of the fulcrum 9 is determined by the vehicle speed.

As described above, the front wheel steering device from the steered wheel l through the gear box 2 and the differential device 3 to the front wheels 6, and in this embodiment of the front wheel steering device, the differential device that also serves as a front wheel turning amount and steering direction detection means. a rear wheel steering device from 3 to 14;
Further, in the embodiment from the differential device 3 and the control device 19 to the rear wheels 14 via the motor 15, a rear wheel phase control device that also serves as a steering angle function generator is configured.

In the above, the i11 control device 19 controls the front and rear wheels to be steered in the same phase in a range where the vehicle speed is greater than a predetermined value, that is, when traveling at high speeds above a certain speed, and as the vehicle speed increases, the front and rear wheels are steered. In low-speed driving in a range where the ratio approaches +1 and the vehicle speed is smaller than the predetermined value, the front and rear wheels are steered or have opposite phases, and as the vehicle speed decreases, the steering ratio of the front and rear wheels approaches -1. It is desirable to define

Next, the function of the differential W13 will be explained in detail.

First, the fulcrum 9 is connected to the connecting part 1 of the arm rods 12 and 13 to the movable arm 8.
8, even if the movable arm 8 swings, the arm rods 12 and 13 do not move in the vertical direction in the figure. Therefore, the right rack 3b is in a fixed state, and this rack 3b
When the pinion 3c that meshes with the pinion 3C rotates while moving vertically in the drawing by operating the steering wheel l, the left rack 3a that meshes with the pinion 3C moves integrally in the vertical direction in the drawing.

As a result, the front wheel 6 is steered from the arm rod 4 via the connecting rod 5, or the movable arm 8 swings around the fulcrum 9 at the joint 18 from the arm rod 4 through the connecting rod 7. Since the arm rod 13 does not move, the rear wheels 14 are not steered and remain in the neutral state shown in the drawing.

If the fulcrum 9 is located to the right of the joint 18 as shown in the figure, the arm rod 12 will move as the movable arm 8 swings around the fulcrum 9.
, 13 are movable in the same direction as the arm rod 4. Therefore, the right rack 3b can move in the opposite direction to the arm rod 4 via the moving joint 11 having a fulcrum in the center, and when the pinion 3C rotates while moving by operating the steering wheel l, it engages with the pinion 3C. At the same time as the matching left rack 3a moves,
It swings from the arm rod 4 through the connecting rod 7 around the moving joint 8 or the fulcrum 9, and from the arm rod 12 through the moving joint 11 and the arm rod 10, it moves to the left while meshing with the right rack 3b or pinion 3C. The rack 3a moves simultaneously in the opposite direction. As a result, the front wheels 6 are steered from the arm rod 4 via the connecting rod 5.

From the arm rod 10 to the rear wheel 1 via the arm rod 11 and the arm rods 12 and 13.
The same phase steering with the front wheels 6 and 4 is performed at the same time.

When the front and rear wheels are steered in the same phase, the left and right racks 3a and 3b are rotated while rotating the pinion 3c based on the difference in the strokes of the connecting rod 7 and arm rod 12 due to the swinging of the moving joint 8 around the fulcrum 9. Since they move in opposite directions, when the right rack 3b is fixed, the amount of movement of the left rack 3a relative to the amount of movement of the pinion 3C increases, that is, the amount of movement of the right rack 3b. left rack 3a according to
The amount of movement will increase.

Furthermore, when the fulcrum 9 is located to the left of the joint 18,
As the moving joint 8 swings around the fulcrum 9, the arm rods 12 and 13 can move in the opposite direction to the arm rod 4, and the right rack 3b can move in the same direction as the arm rod 4. Therefore, as the pinion 3c moves and rotates by operating the steering wheel 1, the left rack 3a moves, and the right rack 3b simultaneously moves in the same direction. As a result, the reverse phase steering of the rear wheels 14 and the front wheels 6 is performed at the same time.

During this reverse phase steering of the front and rear wheels, the left and right racks 3a are similarly adjusted based on the difference in the strokes of the connecting rod 7 and arm rod 12 due to the swinging of the moving joint 8.

3b moves in the same direction while rotating the pinion 3c, so when the right rack 3b is fixed, the left rack 3a is compared to the amount of movement of the pinion 3C.
In other words, the amount of movement of the left rack 3a decreases in accordance with the amount of movement of the right rack 3b.

The jal# of the differential device 3 described above provides the following effects.

In other words, the differential device 3 rotates the pinions 3c of the left and right racks 3a and 3b while rotating the pinions 3c of the left and right racks 3a and 3b, based on the difference in the strokes of the connecting rod 7 and the arm rod 12. By moving in the direction, the amount of movement of the left rack 3a is increased in accordance with the amount of movement of the right rack 3b, and when the front and rear wheels are steered in reverse phase, the same pinions 3c of the left and right racks 3a and 3b are rotated. However, it has a function of reducing the amount of movement of the left rack 3a according to the amount of movement of the right rack 3b by moving both in the same direction.

Therefore, by using this differential g13.

When the front and rear wheels are steered in the same phase, the amount of front wheel steering can be increased by adding an amount corresponding to the amount of steering of the rear wheels 14 to the amount of steering of the front wheels 6, and when the front and rear wheels are steered in opposite phases. When steering, on the other hand, the amount of front wheel turning can be reduced by subtracting an amount corresponding to the amount of turning of the rear wheels 14 from the amount of turning of the front wheels 6. This makes it possible to always maintain a constant ratio between the steering angle of the steered wheels and the difference between the front wheel steering angle and the rear wheel steering angle.

Since the steering device has the above configuration, the ratio between the steering angle of the steered wheels and the difference between the front wheel steering angle and the rear wheel steering angle is always kept constant, and the ratio of the steering angles of the front and rear wheels, that is, the steering ratio is It is determined by the position of the fulcrum 9 of the moving joint 8. This position can be arbitrarily selected relative to the vehicle speed depending on the specifications of the control device 2t19.

FIG. 6 shows a second embodiment. Although only the left wheel is shown in this figure, the relationship with the right wheel is exactly the same as described above.

In FIG. 6, the rotational force applied to the steering wheel 101 is applied by the gear box 102 to the armrest 103 in a straight line! I! and the front wheels 104 are steered.

Furthermore, the arm rod 103 is connected to the end of a moving joint 106 that rotates around a fulcrum 107 via an arm rod 105. Therefore, the movement of the arm rod 103 causes the moving joint 106 to rotate around the fulcrum 107, and steers the rear wheel 109 via the arm rod 10B connected to a point 113 on the moving joint 106. Articulation 106
The fulcrum 107 is fixed to a screw top 112 that is screwed to a screw rod 111 extending from a motor 110 so that it can move on the launch by rotation of the screw rod 111, and is controlled by a vehicle speed sensor 115 and a control device 114. The rotation of the motor 110 causes movement on the moving joint 106.

In this second embodiment, a front wheel steering device from a steering wheel 101 through a gear box 102 to a front wheel 104;
A rear wheel steering device from this front wheel steering device to the rear wheels 109 via front wheel turning amount and steering direction detection means, and a steering angle function generating device from the control device M114 to the rear wheels 109 via the motor 110. A rear wheel phase control device that also serves as a rear wheel phase control device is configured.

With the above configuration, as in the first embodiment, the ratio between the steering angle of the steered wheels and the difference between the front and rear wheel steering angles is always kept constant depending on the vehicle speed, and the steering angle ratio of the front and rear wheels is 106 fulcrums 10
Determined by the position of 7.

It is preferable that the specifications of the control device 114 are also determined in the same manner as described above.

Incidentally, as the vehicle speed detecting means, any known means may be employed as appropriate.

In the case of the steering system of the above embodiment, the steering of the rear wheels is in the opposite phase at very low speeds, and if the steering ratio of the front and rear wheels is determined to suit the characteristics of the vehicle, the steering ratio of the front and rear wheels is determined as shown in Fig. 4. Thus, the direction of the vehicle and the tangent to the turning trajectory can be made to coincide. In other words, at low speeds when the rear wheels are steered in the opposite phase to the front wheels, the steering ratio of the front and rear wheels is controlled to approach -l as the vehicle speed decreases, in other words, the rear wheel steering angle is controlled to reduce the vehicle speed. As a result, the steering angle of the front wheels is brought close to that of the front wheels, so that the straight line connecting the turning center and the center of the vehicle body at extremely low speeds becomes almost perpendicular to the direction of the vehicle, as shown in Figure FF54, and the occurrence of sideslip of the rear wheels is almost eliminated.

Furthermore, according to the steering device of the embodiment, the minimum turning radius can be reduced.

In other words, in the case of steering only the front wheels, the turning radius of the vehicle decreases as the steering angle of the steered wheels increases. The maximum steering angle is limited due to size constraints, and if the steered wheels are also drive wheels, the flexibility angle of the shaft coupling, etc., and therefore there is a limit to the minimum turning radius.

In fact, the steering system of the embodiment reduces the minimum turning radius by nearly 172 degrees by steering the front and rear wheels in opposite phases at low speeds, and also significantly reduces the difference between the inner wheels, making it easy to maneuver even on narrow roads. This makes it easier to drive and park in tight spaces.

Furthermore, the phase change of the front and rear wheels can be continuously performed when the vehicle speed changes from a low speed region to a high speed region or vice versa.

(Effects of the Invention) As described above, according to the present invention, the rear wheels are steered in conjunction with the steering of the front wheels by steering wheel operation, and the front and rear wheels are steered in the same phase at high speeds based on the vehicle speed. Moreover, in order to change the steering ratio of the front and rear wheels to a preset magnitude according to the vehicle speed at high speeds, we have solved the response delay that was a problem with conventional steering systems at high speeds. To steer the front and rear wheels in the same phase while changing the steering ratio in conjunction with front wheel steering based on easily sensed vehicle speed, without having to correct the rear wheel steering due to generated lateral force, etc. It can be achieved with ease. Therefore, while rear wheel steering is linked to front wheel steering, it is possible to perform steering control of the front and rear wheels with excellent steering response at high speeds based on the vehicle speed, making it possible to obtain ease and stability of steering. . Further, according to the present invention, front and rear wheel steering can be performed reliably even on a low slope road where accurate lateral force cannot be detected.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view showing a first embodiment of a steering device that can carry out the steering method of the present invention, Figs. 2 and 3 are schematic diagrams pointing out the problems of the conventional method, and Fig. 4 is a reverse view of the front and rear wheels. FIG. 5 is a schematic diagram explaining the phase steering in detail; FIG. 5 is a schematic diagram explaining the present invention in detail;
FIG. 6 is a schematic plan view of the second embodiment. In addition, in the drawing, l (101) is a handle, and 2 (102)
is the gearbox, 3 is the differential gear, 6 (104) is the front wheel,
14 (109) is a rear wheel, and 20 (115) is a vehicle speed detection means. Patent applicant Honda Motor Co., Ltd. Agent Patent attorney 2 1) Production department Patent attorney Kuni Ohashi Production volume Patent attorney Udo Koyama Patent attorney No. 1)
Figure's3Figure 4Figure 5

Claims (1)

[Scope of Claims] In a vehicle steering method in which the front wheels are steered by steering wheel operation, and the rear wheels are steered in conjunction with the steering of the front wheels, when the speed of the vehicle is greater than a predetermined value, the front wheels and the rear wheels are steered. The wheels are steered in the same direction, and the steering ratio is set to a predetermined size depending on the speed of the vehicle. A method for steering a vehicle, comprising: steering the front wheels at a phase and steering ratio set for the front wheels.