JPS60135368A - All-wheel-steering gear for vehicle - Google Patents

Abstract

PURPOSE:To make steering responsiveness so better at high-speed driving and maneuverability so excellent at low speed, by making the characteristics of a steering ratio function to be set in response to a car speed alterable at discretion in a manual way. CONSTITUTION:A motor 31 is set up at the body side of a left end extension of an arm member 17, while a worm gear 32 is installed in an output shaft of the motor 31, making it engage a section gear 24. And, a car-mount computer 33 is being mounted on a car and this computer 33 receives each signal out of a speed sensor 34, detecting a car speed, and a position sensor 35, detecting a turning position of a link member 21 transmitting a proper control signal commensurate to the car speed to the motor 31 and controlling this speed. On the other hand, a manual select switch 42 is connected to the computer 33 which alters the characteristics of a steering ratio function to be set up in response to the car speed at discretion in a manual way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a front and rear wheel steering device for a vehicle, particularly a four-wheeled vehicle.

The applicant has already proposed a vehicle steering system (Japanese Patent Application No. 134889/1989, etc.) that steers the rear wheels in conjunction with the steering of the front wheels and varies the steering ratio of the rear wheels to the front wheels according to the vehicle speed. did. To give you an overview of this device, at low speeds, the rear wheels are steered in the opposite phase to the front wheels, or almost to zero, while at high speeds, on the other hand, the rear wheels are steered in the same phase as the front wheels. This steering ratio is a continuous function of the vehicle speed, and if the vehicle speed is higher than a certain vehicle speed as a boundary, the steering ratio is positive, that is, in the same phase, and if the vehicle speed is lower than this, the steering ratio is The steering ratio is continuously controlled so that it is negative, that is, in opposite phase (see line Q in Figure 5), and the functions of the steering system are achieved at both low and high speeds. As a result, both the minimum turning radius and the inner wheel difference of the vehicle are significantly reduced at low speeds, improving the maneuverability of the vehicle when entering a garage, driving on narrow curved roads, knee turns, etc. At high speeds, maneuvering response when changing lanes, etc. can be dramatically improved.

By the way, according to such a device, the steering ratio set for the vehicle speed is variably controlled by a single characteristic curve data set in advance.

However, in road conditions, such as highways where there is little need for small turns, even if you are forced to drive at low speeds due to traffic jams, it is possible to drive easily without having to make small turns by changing lanes, etc. On normal roads, depending on subjective factors such as the driver's preference and physical condition while driving, the steering ratio is set to the opposite phase when driving at low speeds to enable small turns during knee turns, etc. When driving at high speeds or at certain high speeds, do not set the steering ratio to the same phase side.
Rather, it would be extremely convenient for the driver if the manner of front and rear wheel steering could be changed elastically and arbitrarily by setting the front and rear wheels to a slightly opposite phase to give a sporty feel.

In view of the above circumstances, the present invention aims to improve this type of front and rear wheel steering device.The purpose of the present invention is to improve the front and rear wheel steering devices based on objective factors such as road conditions, or subjective factors on the driver's side. To provide a front and rear wheel steering device for a vehicle that enables comfortable driving while selectively performing the most appropriate steering and maintaining the advantages of front and rear wheel steering.

In order to achieve the following two objects, the present invention steers the rear wheels in conjunction with the steering of the front wheels, and the steering ratio of the rear wheels to the front wheels is variably controlled in accordance with the vehicle speed. It is applied to the front and rear wheel steering system, and its main component is a changing means that manually changes the characteristics of the steering ratio function corresponding to the vehicle speed, such as a plurality of steering ratios that are preset and stored in the memory of the on-board computer. The present invention is characterized in that it is configured with a switching means that is selectively set based on characteristic data of the function, so that the driver can manually change the characteristics of the steering ratio function.

Below, preferred embodiments that further embody the present invention will be described in detail with reference to the drawings.

First, in order to clarify the present invention, an overview of an example of the configuration and operation of a front and rear wheel steering device in a vehicle will be explained with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing the general basic structure of a vehicle equipped with a front and rear wheel steering system according to the present invention, FIG. 2 is an enlarged perspective view of the rear wheel steering system in FIG. 1, and FIGS. b) and (C) are principle diagrams for explaining the operation.

The handle shaft (2) of the handle (1) is assembled into a rack and pinion type gear box (3), and tie rods (5) are connected to the left and right ends of the rack shaft (4). ), at the outer end of (5) there is a front wheel (7),
Knuckle arm (8) supporting (7), (8)
As is known, the front wheels (7) and (?) are steered in the steering direction of the steering wheel (1).

On the other hand, the pinion shaft (
8), and a universal joint (8) is attached to the rear end of this shaft (8).
A long linkage shaft (10) is connected through the linkage shaft (10). An input shaft (12) is connected to the rear end of the linkage shaft (10) via a universal joint (11), and this input shaft (12) is arranged on the left-right center line of the rear part of the vehicle body, and
) is rotatably supported.

Furthermore, the rear end of the input shaft (12) is connected to a swinging shaft (15) shown in detail in FIG. Fit (16) loosely. As shown in the figure, the center part of an arm member (17) whose length direction is in the width direction of the vehicle body is fixed to this joint member (16). The right end of this arm member (17) is connected to the vehicle body via a link member (18) and a link bracket (19), and the left end is a link member (20).

(21) and link bracket (22) to connect to the vehicle body side. Then, the pivot shaft of the link member (21) (
23) rotates together with the link member (21).

In addition, the inner ends of rear wheel steering tie rods (25) and (25) are connected to the left and right sides of the joint member (1B) through ball joints (2B) and (2B), and both tie rods (25) , (25) are connected to the knuckle arms (28) that support the rear wheels (27), (27) as shown in FIG.
), connect to (28).

On the other hand, a motor (31) is disposed on the vehicle body side of the left end outer extension of the arm member (17), a worm gear (32) is disposed on the output shaft of this motor (31), and a worm gear (32) is disposed on the output shaft of the motor (31).
4). In addition, the vehicle is equipped with an on-board computer (33), and this computer (33) includes a vehicle speed sensor (30) and a link part 1t (2) that detects the vehicle speed.
1) receives a signal from the position sensor (35) that detects the rotational position of the motor (31
) to control this rotation.

If the pivot point P of the joint member (18) coincides with the center O of the input shaft (12) as shown schematically in FIG. 3(a), the input shaft (12) and the swing shaft The joint member (16) rotates concentrically with (15), and at this time the joint member (16) does not swing from side to side.
is stationary, and at this time, only the front wheels (7) l' (7) are steered, and the rear wheels (27), (27) are not steered at all as in the conventional vehicle.

Further, when the vehicle speed is lower than the set value and the vehicle is running at low speed, the computer (33) receives a signal from the vehicle speed sensor (34) and makes a judgment, and controls the rotation of the motor (31).
) The worm gear (32) formed on the output shaft of the worm gear (32) rotates the sector gear (24) that meshes with the worm gear (32), and the link member (21) that rotates together with the sector gear (24) rotates around the pivot shaft (23). The arm member (
17) is inclined so that the left end is downward as shown in FIG. 3(b). Due to the inclination of the arm member (17), the pivot point P is located below the axis center 0, and at this time, if the input shaft (12) is rotated counterclockwise by θ, for example,
The tie rods (25), (25) move to the right as shown by the broken lines in FIG.
7), the vehicle is steered in the opposite direction to (7), and the front rear wheel steering ratio at this time is continuously changed in accordance with the vehicle speed.

Furthermore, if the vehicle speed increases beyond the initial set value, the computer (33) causes the motor (31) to reverse, so that the arm member (17) moves in the opposite direction as before, as shown in Figure 3(c). As a result, the pivot point P is located above the shaft center O, and if the input shaft (12) is rotated counterclockwise by an angle (θ) as described above, the tie rod (25)
, (25) operate in the opposite manner to the above as shown by the broken lines in FIG.
, (7), and the front/rear wheel steering ratio at this time is continuously changed according to the vehicle speed. The characteristics of the steering ratio function for the above vehicle speeds are shown by the curve (Q
).

Next, the main structure and functions of the present invention will be specifically explained with reference to FIGS. 2, 4, and 5. Fourth
The figure is a functional block diagram of the rear wheel steering control system, and FIG. 5 is a characteristic diagram of the front/rear wheel steering ratio function with respect to vehicle speed.

First, the configuration will be explained. As shown in FIG. 2, the in-vehicle computer (33) has a plurality of push buttons (36) and (37).
, (38), (39), (40), and (41) are arranged in the lateral force, respectively, as a manual selection switch (42).
Connect. This selection switch (42) is used to manually change the characteristics of the steering ratio function that is set in accordance with the vehicle speed mentioned above. to enable operation.

Next, the function of the rear wheel steering control system will be explained. Fourth
As shown in the figure, the vehicle speed signal detected from the vehicle speed sensor (34) is sent to the computer (33) as predetermined vehicle speed data (U).
Enter. This vehicle speed data (u) is converted to corresponding steering ratio data (ko) by the conversion process (a).
) (= f (u) ).

To explain this process (a) in detail, first, the steering ratio data (ko) corresponding to this vehicle speed data (u) is set and stored in advance as conversion data (b) in the memory of the computer (33). This conversion data (b) is represented by a plurality of conversion characteristics shown in FIG.

On the other hand, the selection information selected by the selection switch (42) is given to the conversion process (a) to produce a plurality of characteristic curves shown in FIG. 5, that is, characteristics (lk) of a plurality of preset steering ratio functions. , (2k), (3k), (4k)...
One characteristic is selected from (N k), and each characteristic (lk), (2k)... (N k) is selected by the selection switch (
Corresponding to each push button (36), (37)...(41) in 42), the conversion process (a) corresponds to the actual vehicle speed according to the characteristic selected from the conversion characteristics shown in FIG. This will be converted to steering ratio data. On the other hand, the position sensor (35
) detects the rotational position of the link member (21),
This rotational position is proportional to the steering ratio in the actual steering state, and this detection result is input to the computer (33) as actual steering ratio data (km). Then, relative difference data (Δk) of (km)-(ko) is obtained from this actual steering ratio data (km) and the aforementioned steering ratio data (ko) through a comparison process (c). This difference data (Δk) is data for correcting the steering ratio to a required value, and is output from the computer (33) and input to the output control device (43).

The output side of this output control device (43) is connected to the motor (31).
) is connected to the control signal (
s). Therefore, the motor (31) rotates and is corrected until the steering ratio corresponds to the current vehicle speed.

The characteristics of the steering ratio function corresponding to vehicle speed are set as shown in Fig. 5, and the characteristic curve (1k) side has sportiness, and (
2k), (3k), etc. The larger the number, the easier the steering becomes. Further, each process in the computer (33) is executed by a predetermined control program (software) stored in the computer (33).

Although the on-vehicle computer (33) was used in the above embodiments, it may be configured with an electric circuit consisting of a combination of its low-speed functions, and the selection switch was configured with a push button, but other continuous It may also be a sliding changing means that can be changed. Furthermore, the present invention is not limited to the embodiments, but may include a front and rear wheel steering device that hydraulically controls the steering of the front and rear wheels and transmits front wheel steering angle information using hydraulic pressure, or a computer (33) that transmits the front wheel steering angle as an electrical signal. It can be similarly applied to a front and rear wheel steering device, etc. that transmits information to the front and rear wheels.

As described above, the present invention provides a front and rear wheel steering device that steers the rear wheels in conjunction with the steering of the front wheels and variably controls the steering ratio of the rear wheels relative to the front wheels in accordance with the vehicle speed. Since the characteristics of the steering ratio function can be manually changed arbitrarily, road conditions 1 can be adjusted depending on objective factors such as driving on a highway, or subjective factors such as driver preference. The most appropriate steering can be selectively carried out, thereby achieving the advantages of front and rear wheel steering, that is, good steering response when driving at high speeds, and good maneuverability of the vehicle when driving at low speeds. While maintaining the basic effect of
You can drive comfortably.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the general basic structure of a vehicle equipped with a front and rear wheel steering system according to the present invention, FIG. 2 is an enlarged perspective view of the rear wheel steering system in FIG. 1, and FIG. b) and (
c) is a principle diagram for explaining the operation, Fig. 4 is a functional block diagram of the rear wheel steering control system showing the main configuration of the present invention, and Fig. 5i is a characteristic diagram of the front/rear wheel steering ratio function with respect to vehicle speed. . In the drawing, (33) is an on-vehicle computer, (34) is a vehicle speed sensor, (35) is a position sensor, (36), (37)
, (38). (39), (40), (41) are push buttons, (42) is a selection switch, (a) is a conversion process, (b) is conversion data,
(c) is a comparison process. Patent applicant: Honda Motor Co., Ltd. Agent Patent attorney: 1) Yobetsu Patent attorney: Kuni Ohashi Patent attorney: Yu Koyama

Claims (2)

[Claims] (1) In a front and rear wheel steering system for a vehicle that steers the rear wheels in relation to the steering of the front wheels and variably controls the steering ratio of the rear wheels relative to the front wheels in accordance with the vehicle speed, a steering ratio function corresponding to the vehicle speed is used. 1. A front and rear wheel steering device for a vehicle, characterized in that the front and rear wheel steering device for a vehicle is provided with a changing means for arbitrarily changing the characteristics manually. (2) The changing means is constituted by a switching means that selectively sets the characteristic data of a plurality of steering ratio functions corresponding to the vehicle speed, which are preset and stored in the memory of the on-vehicle computer. The front and rear wheel steering device for a vehicle according to item 1.