JPS6118573A - Steering system for car - Google Patents

Abstract

PURPOSE:To facilitate the steering while to improve the stability by performing in-phase or reverse phase steering control of rear wheel with correspondence to the steering amount of front wheel. CONSTITUTION:Upon steering of steering wheel 7 to the right, the front wheels 8, 9 are steered to the right. At the same time, a rod 1 is pushed rearward to slide a camboard 3 rearward in the cam case 2. Since counter S-shaped cam groove 4 is formed in the camboard 3, rearward sliding of camboard 3 will cause rightward motion of pin 6 thus to steer the rear wheels 10, 11 to the right. Upon steering further to the right, the steering angle of rear wheel to the right will pass through the maximum level then decrease gradually because of the motion of the pin 6 along the cam groove 4 while upon further increase of the steering angle, the rear wheel is steered to the left.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a steering system for 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 the front wheels start turning when the vehicle is running, a slip angle is first generated in the front wheels, and the cornering force generated by this causes lateral movement of the vehicle body and yawing around the center of gravity of the vehicle.

The rear wheels develop a slip angle only after they begin to be displaced in one direction as a result of the yaw motion of the vehicle body. Therefore, there is a phase lag in the cornering force generated by the rear wheels 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 is the reason why the steering of a four-wheeled vehicle requires skill. 6 Additionally, while a four-wheeled vehicle is turning by steering, the wheels tend to skid, so the tangent to the turning trajectory always lines up with the vehicle axis. It is not always possible to drive a four-wheeled vehicle, and this is another reason why it requires skill to steer a four-wheeled vehicle.

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 vehicle appropriately. A certain amount of driving experience is required.

As a means to solve the problems with such 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 of giving the rear wheels a steering angle proportional to the sideslip angle of the rear wheels, and US Pat. A method for controlling the amount of steering is disclosed.

(Problems to be Solved by the Invention) However, these known techniques not only have technical problems with the sideslip angle or G sensors that control 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 delay in response to steering occurs.

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 achieved simply by switching the control mode of the
．． No. 6, Special Publication No. 53-26732).

Therefore, an object of the present invention is to focus on the fact that in four-wheeled vehicles, the amount of front wheel steering at medium to high speeds is generally within a relatively small range, and to solve the problems of conventional devices in steering at medium to high speeds. The amount of steering of the rear wheels can be determined by a factor that can be easily detected, without using complicated sensors and mechanisms, and without having to correct rear wheel steering due to generated lateral force. The aim of the present invention is to develop a steering system that can be achieved by predicting the situation and achieve ease and stability of steering, as well as reduce the turning radius and improve maneuverability of the vehicle without the need for switching the system. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a front wheel steering device that is linked to steering wheel operation, a rear wheel steering device that is mechanically interlocked and connected to the front wheel steering device, and a front wheel steering device that is connected to the front wheel steering device. A rear wheel steering angle function generating device that is provided in a power transmission path from the device to a rear wheel steering device and that varies a ratio between a front wheel turning amount and a rear wheel turning amount based on the front wheel turning amount. , and a rear wheel steering direction converting device which is provided in the same power transmission path and controls the steering of the rear wheels to be in the same phase or opposite phase to the front wheels based on a predetermined amount of steering of the front wheels.

Specifically, the rear wheel steering angle function generating device and the rear wheel steering direction converting device have a substantially S-shaped or reverse S-shaped shape formed on the cam in plan view.
It consists of a letter-shaped cam groove and a pin engaged with the cam groove.

(Function) In order to obtain the lateral acceleration necessary for turning the vehicle, a large steering angle is required when driving at low speeds, but at high speeds, the required steering angle gradually becomes smaller. Therefore, according to the steering system according to the present invention, the front and rear wheels are steered in the same phase at a small steering angle, so when operating at high speed, a slip angle is generated in the rear wheels at the same time as the front wheels, resulting in cornering force. , the vehicle's lateral acceleration reaches the value intended by the driver in a short period of time, and steering response is significantly improved.

When the required steering angle increases as the vehicle speed decreases, the amount of steering angle of the rear wheels decreases, and therefore the degree of improvement in the response described above also decreases, but this is not so important for the steering response at low speeds. , there is no problem in practice.

Next, the relationship between the direction of the vehicle and the turning locus when the steering system according to the present invention is used will be explained with reference to FIGS. 3 to 6.

Although all the figures are shown with two wheels, there is no risk of impairing the validity of the explanation if the turning radius is sufficiently large compared to the wheel pressure, such as in a general four-wheeled vehicle.

FIGS. 3 and 4 are examples of conventional steering devices that steer only the front wheels. In the case of a turn at very low speed, the direction of movement of the vehicle coincides with the orientation of the tires, so the direction of the vehicle faces outward from the tangent to the turning locus, as shown in FIG. When the vehicle speed increases, a slip angle occurs in the front and rear wheels, and the direction of motion of the front and rear wheels points outward from the plane of the tire. 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, the fourth
As shown in the figure, the direction of the vehicle body is inward from the tangent to the turning trajectory.

In the steering system according to the present invention, when turning at low speed, a region with a large steering angle is used, so the front and rear wheels are steered in opposite phases. Thus, the difference between the direction of the vehicle and the tangent to the turning trajectory can be made sufficiently small.

Generally, the required steering angle decreases as the vehicle speed increases, so
The steering angle of the rear wheels changes from the opposite phase to the same phase as the steering angle O1, making it possible to maintain a small difference between the vehicle direction and the tangent to the turning trajectory even at high speeds, as shown in FIG. Furthermore, according to the steering system of the present invention, the minimum turning radius can be reduced. In other words, the turning radius of the vehicle decreases as the steering angle of the steered wheels increases, but there are also dimensional constraints on the brake hoses etc. connected between the wheels and the vehicle body, dimensional constraints on the wheel house that protrudes into the vehicle interior, and furthermore. When the steered wheels are also drive wheels, the maximum steering angle is limited due to constraints on the flexibility angle of the shaft coupling, and therefore there is a limit to the minimum turning radius. According to the steering device of the present invention, since the front and rear wheels are steered in opposite phases at low speeds,
The minimum turning radius is reduced by nearly half, and the difference between the inner wheels is also significantly reduced, making it easier to drive on narrow roads and park in tight spaces.

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

FIG. 1 is a schematic plan view showing an embodiment of the steering system of the present invention. The linear motion is converted into a linear motion within the gear box (12) by a well-known method such as Nion, and the linear motion is transmitted by a known linkage such as a tie rod and a knuckle arm (13), and the front wheels (8) and (9) are Be steered.

The steering mechanism for the front wheels (8), (8) described above is entirely the same as the conventional one.

A rod (1) connected to a point (10) that is linked to the steering of the front wheels (8) and (9) extends rearward and is slidably housed in a cam case (2) provided at the rear. Cam plate (3
) to which the rod page 1) is connected. The cam plate (3) is provided with a substantially inverted S-shaped cam groove (4) as shown enlarged in FIG. 2, and a pin (6) slides along the groove in the cam groove (4). is engaged to do so. Both rear wheels (10) and (11) are connected, and both rear wheels (10) and (1
1) Rear wheel tie rod (5
) and the pin (8) that moves in the cam groove (4),
When the pin (8) moves through the cam groove (0), the rear wheel tie rod (5) moves in the axial direction according to the shape of the cam groove, and the rear wheel is steered.

Next, the operation of the steering system according to the present invention will be explained.

In the figure, when the steering wheel (7) is steered to the right, the front wheels (8) and (9) are steered to the right. At the same time, the rod (1) is pushed rearward, causing the cam plate (3) connected to the rod (1) to slide rearward within the cam case (2). The cam groove (4) provided in the cam plate (3) is the second
As shown in the figure, it is formed in an inverted S-shape with both ends (4b) and (4c) extending substantially linearly from the middle curved part (4a), so that the cam plate (3) slides rearward. When starting, the pin (8) moves to the right in the figure, moves the rear wheel tie rod (5) in the right axial direction, and connects the rear wheel (IQ), (1
1) Turn the wheel to the right. When the steering wheel is further rotated to the right, the cam plate (3) slides further rearward, and the movement of the pin (6) that moves along the cam groove (4) maximizes the rightward steering angle of the rear wheel. As the steering angle of the steered wheels increases, the rear wheels begin to turn to the left in the opposite direction, and near the maximum steering angle of the steered wheels, the rear wheel steering angle is almost equal to the front wheel steering angle. The steering will be the same amount and in the opposite direction.

It is clear from the figure that when the steered wheels are steered to the left in the figure, a similar operation is shown, only that the steering direction of the front and rear wheels is reversed.

(Effects of the Invention) As described above, according to the present invention, it is possible to eliminate the delay in steering response, which was a problem with conventional devices, especially in steering at medium and high speeds, without using complicated sensors and mechanisms. This is achieved by steering the rear wheels in response to the same phase as the front wheel steering direction based on the amount of front wheel steering that can be easily sensed, without having to correct rear wheel steering due to generated lateral force, etc. Therefore, with a simple configuration, it is possible to perform steering control of the front and rear wheels with excellent steering response at medium and high speeds, and to obtain ease and stability of steering. It is also possible to improve the maneuverability of the vehicle.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view showing one embodiment of the steering device of the present invention, Fig. 2 is an enlarged view of the cam, Figs. FIG. 6 is a schematic diagram illustrating the present invention in detail. In the drawings, (1) is the rod, (3) is the cam plate, (0 is the cam groove, (5) is the rear wheel steering member, (6) is the bottle, (8)
, (ill) are the front wheels, and (10) and (11) are the rear wheels. Patent applicant Honda Motor Co., Ltd. Agent Patent attorney 2 1) Yoichi Department patent attorney Kuni Ohashi Department patent attorney Yuki Koyama Patent attorney No 1)
Shigeru Figure 1 Figure 2 b Figure 3 Figure 5 Figure 4 ° Figure 6

Claims (1)

[Scope of Claims] 1) A front wheel steering device that is linked to steering wheel operation, a rear wheel steering device that is mechanically interlocked and connected to the front wheel steering device, and a power transmission path from the front wheel steering device to the rear wheel steering device. A rear wheel steering angle function generating device is installed in the same power transmission path and makes the ratio between the front wheel turning amount and the rear wheel turning amount variable based on the front wheel turning amount. A vehicle steering device comprising a rear wheel steering direction conversion device that controls steering of the rear wheels to be in the same phase or opposite phase to the front wheels after a predetermined amount of steering is reached. 2) The rear wheel steering angle function generating device and the rear wheel steering direction converting device consist of a cam groove formed in a cam and having an approximately S-shape or inverted S-shape in plan view, and a pin engaged with the cam groove. A vehicle steering system according to claim 1.