JPS61220972A - All-wheel steering gear for vehicles - Google Patents

Abstract

PURPOSE:To improve the maneuverability of a car at low speed ever so better, by making a low-speed range function where steering for both front and rear wheels comes to the same phase and smoothly shifts to a car speed function, selectable by hand, in case of a device which sets a steering ratio of both front and rear wheels down to the car speed function and controls it variably. CONSTITUTION:A proper control signal commensurate to a car speed is outputted to a motor 31 by a computer 33 inputting each output signal out of a car speed sensor 34 and a manual select switch 41 selecting a position sensor (actual steering ratio sensor) 35 and a steering ratio, and relating a rear wheel to steerage of a front wheel by c.w. or c.c.w. rotation of this motor 31, they are steered so as to become opposite phase at low speed but the same phase at high speed, respectively. The select switch 41 is made up of installing pushbuttons 36-40 selecting either of characteristics 1k, 2k...nk, *k of plural preset steering ratio functions. And, when the pushbutton 40 is pressed, it comes to the same phase at low speed and thereby the steering ratio characteristic *k to be connected to the steering ratio characteristic nk smoothly is made selectable.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a front and rear wheel steering device for a four-wheel vehicle or the like.

<Prior Art> The present applicant has already developed a vehicle front and rear wheel steering system (patent application) 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. 57-134889, etc.). This device steers the rear wheels in the opposite phase or almost zero at low speeds, and on the other hand, at high speeds, 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 negative. In other words, the steering ratio is continuously controlled so that the phases are opposite to each other (see line Q in FIG. 5), and the functions of the steering system at low and high speeds are compatible.

As a result, at low speeds, the minimum turning radius and inner wheel difference of the vehicle are both significantly reduced, making it easier to park, drive on narrow curved roads, and
It is possible to dramatically improve the maneuverability of the vehicle when making turns, etc., and it is also possible to dramatically improve maneuverability when changing lanes at high speeds.

This is especially useful when driving on curved roads at low speeds, eliminating the difference between the inner wheels by setting the steering ratio in opposite phases, and when driving on extremely narrow roads or parking in limited spaces. However, on the other hand, when turning, the rear of the vehicle is swayed sideways, making it difficult to parallel park or pull alongside. Therefore, at low speeds, it is preferable to manually set the steering ratio to approximately 1.0 in the same phase as necessary. In that case, if the steering ratio remains in the same phase at approximately 1.0 until after the vehicle speed has increased to a certain extent, it will be difficult for the driver to turn the vehicle as desired. It is necessary to cancel the operation, which imposes an operational burden on the driver.

<Problems to be Solved by the Invention> In view of the above problems of the prior art, the main object of the present invention is to provide a system in which the front wheels are steered in opposite phases at low speeds and in phase at high speeds. A front and rear wheel steering system for a vehicle that steers the rear wheels so that the rear wheels are aligned and variably controls the steering ratio of the rear wheels relative to the front wheels as a function of at least one vehicle speed, allows parallel parking, side-to-side parking, etc. as necessary. To provide a front and rear wheel steering device for a vehicle, which can be used for steering the front and rear wheels of a vehicle without imposing an operational burden on the driver.

<Means for Solving the Problems> According to the present invention, it is an object of the present invention to provide a front and rear wheel steering system of the above type with a low speed system that has the same phase at low speeds and smoothly transitions to the above vehicle speed function. This is achieved by providing a front and rear wheel steering system for a vehicle, characterized in that it is equipped with selection means that can manually select a region function.

<Operation> In this way, it is possible to manually select the steering ratio functions so that they are in the same phase at low speeds, and there is no problem even if the driver increases the vehicle speed without canceling the manual selection. Since the vehicle can be driven easily, the maneuverability of the vehicle at low speeds can be optimized without imposing any operational burden on the driver.

<Embodiments> Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

1 to 3 show an embodiment of the configuration of a front and rear wheel steering device to which the present invention is applied. The handle shaft 2 of the handle 1 is built into a rack and pinion gear box 3, and tie rods 5.5 are connected to the left and right ends of the rack shaft 4, and a front wheel 7.7 is connected to the outer ends of both tie rods 5.5. The supported knuckle arm 6.6 is connected and, as is known,
The front wheels 7.7 are steered in the steering direction of the steering wheel 1.

On the other hand, a rear hennion shaft 8 is led out from the gear box 3, and a long linkage shaft 10 is connected to the rear end of this shaft 8 via a universal joint 9. Wt of linkage shaft 10
An input shaft 12 is connected to Q via a universal joint 11, and this input shaft 12 is located on the left-right center line of the rear part of the vehicle body and is rotatably supported by a bearing bracket 13.

Further, a swing shaft 15 shown in detail in FIG. 2 is connected to the rear end of the input shaft 12 via a clevis 14, and a joint member 16 is loosely fitted in the middle of the swing shaft 15. Tie rods 25.25 are connected to the left and right ends of the joint member 16 via ball joints 26.26, and the joint member 16 is fixed to the center of an arm member 17 provided along the width direction of the vehicle body. .

One end of this arm member 17 is connected to the vehicle body through a link member 18 and a link bracket 19, and the other end is connected to the vehicle body through link members 20, 21 and a link bracket 22.

A pivot shaft 23 on the bracket side of the link member 21 rotates integrally with the link member 21. The outer ends of both tie rods 25.25 are connected to knuckle arms 28.28, which support rear wheels 27.27, as shown in FIG.

A motor 31 is provided on the vehicle body portion on the other end side of the arm member 17.
A worm gear 32 is attached to the output shaft of the motor, and meshes with a sector gear 24 that is integrally attached to the pivot shaft 23 of the link member 21. The vehicle is also equipped with an on-board computer 33, and this computer 33 is connected to a vehicle speed sensor 34 that detects vehicle speed and a link member 2.
In response to a signal from a position sensor 35 that detects the rotational position of the pivot shaft 23, the motor outputs an appropriate control tll signal according to the vehicle speed.
Send it to evening 31 and control its rotation. A manual selection switch 42 is further connected to the computer 33 so that the steering ratio of the rear wheels can be controlled based on the function characteristic selected by the manual selection switch 42.

As shown in FIG. 3(a), when the pivot point P of the joint member 16 coincides with the center O of the input shaft 12, the input shaft 12 and the swing shaft 15 rotate concentrically. However, at this time, the joint member 16 does not swing from side to side, so the tie rods 25.25 remain stationary, only the front wheels 7.7 are steered, and the rear wheels 27.27 are not steered at all as in the conventional vehicle.

By controlling the rotation of the motor 31, the link member 21 is
When the arm member 17 is tilted downward, the arm member 17 is tilted downward.
), the left end is tilted downward. Due to this inclination of the arm member 17, the pivot point P is displaced below the shaft center O. At this time, if the input shaft 12 is rotated, for example, by θ in the counterclockwise direction, the tie rods 25 and 25 are moved as shown in FIG. In b), as shown by the broken line, the rear wheel 27.
27 will be steered in the opposite direction to the front wheels 7.7.

When the motor 31 is reversed and the link member 21 is tilted upward in the opposite direction, the arm member 17 is tilted so that its left end is upward as shown in FIG. 3(C). As a result, the pivot point P is displaced above the axis center 0, and if the input shaft 12 is rotated counterclockwise by the angle θ in the same manner as described above, the tie rods 25 and 25 are moved to the position shown in FIG. 3(C). As shown by the broken line, the rear wheels 27.27 are also steered in the same direction as the front wheels 7.7.

Next, the operation of the above embodiment will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows the functional configuration of the computer 33.
The vehicle speed signal detected by the vehicle speed sensor 34 is input to the computer 33 as a predetermined vehicle speed signal U. This vehicle speed signal U is a steering angle ratio signal k preset by the conversion process (a). (-f(u)〉. This conversion process (
In b), a plurality of functional formula data f, f2, . . . stored in the memory (0) of the computer 33 are used.
The vehicle speed signal U is converted into steering ratio data according to one of a plurality of conversion characteristics shown in FIG.

The selection information b2 selected by the selection switch 41 is
After the selection process (d), 12k, . . . are applied to the plurality of characteristic curves shown in FIG. ...n
Select one of them for k1*. Each of these characteristics corresponds to each of the push buttons 36 to 40 of the selection switch 41, and the conversion process (a) is performed by converting the actual vehicle speed to the corresponding steering according to one characteristic selected from the conversion characteristics shown in FIG. This will be converted into ratio data. These pushbuttons 36-40 are self-illuminated so that the driver can easily determine which steering ratio function is selected.

The position sensor 35 detects the rotational position of the link member 21, and this rotational position is proportional to the steering ratio in the actual steering state, and this detection result is the actual steering ratio data kIl.
It is input to the computer 33 as . This actual steering ratio data and the steering ratio data k. kl-k by comparison processing (c). Get the relative difference Δ. This difference Δ is input from the computer 33 to the output control device 42 as data corresponding to the amount of correction of the steering angle ratio necessary to realize the required steering ratio. This output ill III
The output side of the device @42 is connected to the motor 31 and supplies a control signal @S corresponding to the difference Δk. In this way, the motor 31 is rotated in a direction that achieves a steering ratio corresponding to the current vehicle speed.

As shown in Fig. 5, the characteristics of the steering ratio function corresponding to vehicle speed are as follows: From the curve corresponding to nk, multiple curves that are approximately parallel to each other correspond to lk, 2k, 3k, . . ., respectively. The characteristic curve 1 side corresponds to sportier movement characteristics, the 2nd side, the 3rd side, etc.
...The larger the number, the easier the steering becomes.

In particular, according to the present invention, a *'' push button 40 is provided for the convenience of side-by-side parking, parallel parking, etc. By pressing this push button, as shown by the curve P in FIG. At low speed, the steering ratio is approximately 1.0 in the same phase,
As the vehicle speed increases, it is possible to obtain a steering ratio characteristic represented by a curve that touches the horizontal line of zero steering ratio and then smoothly connects to the curve nK. Even if this steering ratio characteristic is selected, there is no change in the steering characteristic of the vehicle in the medium to high speed range, so even if the vehicle speed increases, there is no need to immediately cancel the selection state, and the maneuverability of the vehicle will be impaired. It won't happen. The characteristics of this slow region function can be set as necessary, and the fifth
As shown by the imaginary line in the figure, the phases may be opposite in the medium speed range, or the phases may be the same throughout.

In the above embodiment, each process in the computer 33 is executed by a predetermined control program (
Although it is executed by software (software), it can also be configured by an electrical circuit consisting of a combination of other similar functions. Furthermore, although the selection switch is configured as a push button, it may also be a sliding changing means that can continuously change the selection switch.

Further, the present invention is not limited to the above-mentioned 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 transmits the front wheel steering angle to the computer 33 as an electrical signal. The present invention can be similarly applied to front and rear wheel steering devices.

<Effect> As described above, according to the present invention, the basic advantage of front and rear wheel steering is that the steering response is good when driving at high speeds, and the maneuverability of the vehicle is good when driving at low speeds. It is possible to further provide steering ratio characteristics that are convenient for side-by-side parking, parallel parking, etc.

Moreover, when such a steering ratio characteristic is selected, the steering angle does not change suddenly, and even if the vehicle speed is increased, there is no problem in driving operation.
The effect of further improving the maneuverability and handleability of a vehicle with front and rear wheel steering can be achieved.

4. 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 device to which the present invention is applied.

FIG. 2 is an enlarged perspective view of the rear wheel steering system.

FIGS. 3(a), 3(b) and 3(c) are conceptual diagrams showing the operating principle of the rear wheel steering system.

FIG. 4 is a block diagram showing the functional configuration of the on-vehicle computer.

FIG. 5 is a steering angle ratio output characteristic diagram in the above embodiment.

1... Handle 2... Handle shaft 3...
Gear box 4...Rack shaft 5...Tie rod 6...Knuckle arm 7...Front wheel
8... Binion shaft 9... Universal joint 10.
... Linkage shaft 11 ... Universal joint 12 ...
Input shaft 13...bearing bracket 14...clevis 1
5... Swing shaft 16... Joint member 17
...Arm member 18...Link member 19...
Bracket 20.21... Link member 22...
Bracket 23... Pivot 24... Sector gear
25... Tie rod 26... Ball joint 27
... Rear wheel 28 ... Knuckle arm 31 ... Motor 32 ... Worm gear 33 ... Computer 34
...Vehicle speed sensor 35...Position sensor 36-40
...Push button 41...Manual selection switch 42...Output device patent applicant Honda Motor Co., Ltd.
Attorney Patent Attorney Yo Oshima
-Figure 2Figure 3

Claims (1)

[Claims] The rear wheels are steered in relation to the steering of the front wheels so that they are in opposite phases at low speeds and in the same phase at high speeds, and the steering ratio of the rear wheels relative to the front wheels is adjusted to at least one vehicle speed. A front and rear wheel steering system for a vehicle that is variable controlled as a function, characterized by comprising a selection means that can manually select a low speed region function that has the same phase at low speeds and smoothly transitions to the vehicle speed function. Vehicle front and rear wheel steering system.