JPH04869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an improvement in a front and rear wheel steering device for a vehicle that can variably control the steering angle of the rear wheels relative to the front wheels.

<Prior Art> The present applicant has already developed a vehicle steering system (patent application No. 57) that steers the rear wheels in conjunction with the steering of the front wheels and also varies the steering angle ratio of the rear wheels to the front wheels in accordance with the vehicle speed.
-134888 (see Japanese Unexamined Patent Publication No. 59-26363, etc.). To give 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, and at high speeds, on the other hand, the rear wheels are steered in the same phase as the front wheels. let As shown by D in Figure 6, this steering angle ratio becomes a continuous function of the vehicle speed, and if the vehicle speed becomes higher than a predetermined vehicle speed _d1 as a boundary, the steering angle ratio becomes positive, that is, the phase becomes the same. , if the vehicle speed is lower than this, the steering angle ratio becomes negative, that is, the phase is opposite. Continuous control of the steering angle ratio is performed according to this function curve D, and the functions of the steering system are made compatible at low and high speeds. This significantly reduces both the vehicle's minimum turning radius and the difference between the inner wheels at low speeds, dramatically improving the maneuverability of the vehicle when parking in a garage, driving on narrow curved roads, making U-turns, etc. On the other hand, at high speeds, the steering response can be dramatically improved.

By the way, when parallel parking at low speeds or pulling over in a narrow space, if the front wheels and rear wheels are steered in opposite phases, the rear of the vehicle may be swayed laterally, which is inconvenient. This may result in easier steering operation if the wheels are steered in the same phase. Further, even at medium to high speeds, there may be cases where the driver wants to maintain the steering angle ratio at a certain constant value depending on his/her preference. Therefore, by providing a manual switching means in such a front and rear wheel steering device, such a demand can be met.

However, for example, if a manual selection state suitable for a low speed range is maintained in a medium to high speed range, the maneuvering response of the vehicle is not necessarily appropriate, and the movement of the vehicle may go against the driver's wishes. Further, even if the driver is aware that manual selection is being performed, there would be no problem, but in an unexpected situation, the driver may feel a great deal of discomfort.

<Problems to be Solved by the Invention> In view of these inconveniences, the main object of the present invention is to significantly improve the maneuverability of a vehicle by providing a manual switching means, and to provide manual selection. It is an object of the present invention to provide a front and rear wheel steering device for a vehicle that can issue a warning to a driver when the condition is inappropriate.

<Means for Solving the Problems> According to the present invention, such an object is achieved by using a front and rear wheel steering system of a vehicle that variably controls the steering angle of the rear wheels according to certain conditions. selects one or more pieces of steering angle ratio information or rear wheel turning angle information and the steering angle ratio information or rear wheel turning angle information, and realizes the steering angle ratio or rear wheel turning angle corresponding to the selected information. and an alarm generating means that detects the shift position of the gear shift lever and issues an alarm when the shift position is shifted up to a high speed position with manual switching selected. This is achieved by providing a front and rear wheel steering system for a vehicle.

<Function> As described above, if the shift position of the gear shift lever is changed to a medium-high speed position while manual switching is selected, that is, when the vehicle becomes capable of traveling at high speeds above a certain level, an alarm is issued. By prompting the driver to cancel manual switching or confirm the setting mode, or by warning the driver not to increase the vehicle speed, it is possible to avoid the inconvenience of the vehicle exhibiting operational responsiveness that is contrary to the driver's wishes. .

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the drawings, Fig. 1 is a perspective view showing the general basic structure of a vehicle equipped with a front and rear wheel steering system, Fig. 2 is an enlarged perspective view of the rear wheel steering system, and Figs. 3 a, b, and c show its operation. It is a broken side view showing the principle.

First, in order to clarify the present invention, FIGS.
The configuration and operation of the front and rear wheel steering device will be explained with reference to the drawings. A handle shaft 2 of the handle 1 is incorporated into a rack and pinion type gearbox 3, and tie rods 5, 5 are connected to the left and right ends of the rack shaft 4, and front wheels 7, 7 are supported at the outer ends of both tie rods 5, 5. Knuckle arms 6, 6 are connected, and the front wheels 7, 7 are steered in the steering direction of the steering wheel 1, as is known.

On the other hand, a pinion shaft 8 is led out rearward from the gear box 3, and a universal joint 9 is connected to the rear end of this shaft 8.
A long linkage shaft 10 is connected via the linkage shaft 10.
An input shaft 12 is connected to the rear end of the linkage shaft 10 via a universal joint 11.
is arranged on the left and 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. A tie rod 18 is connected to the left and right ends of this joint member 16 via ball joints 17, 17.
18 are connected, and the joint member 16 is swingably supported by links 21, 22 and a bracket 23 toward the vehicle body. Also, both tie rods 1
Knuckle arms 19, 19 supporting rear wheels 20, 20 are connected to the outer ends of the wheels 8, 18.

An arm 25 is provided at the rear end of the swing shaft 15.
is fixed so as to protrude downward, a link 26 is pivotally attached to the lower end of this arm 25 so as to be freely rotatable in the vertical direction, and a slider 27 is attached to the rear end of the link 26.
is also pivotally mounted so as to be freely rotatable in the vertical direction.
This slider 28 is connected to the output shaft 3 of a motor 29 via a ball screw mechanism 28 as shown in FIG.
0 is screwed together, and this output shaft 30 is connected to the input shaft 12.
A motor 29 is fixed to the vehicle body so as to be coaxially located at the rear.

On the other hand, the vehicle is equipped with an on-board computer 31, which receives signals from a vehicle speed sensor 32 that detects the vehicle speed and a position sensor 33 that detects the position of the slider 27, and outputs appropriate control signals according to the vehicle speed. Supplied to the motor 29.

When the slider 27 is in the position shown in FIG. 3a and the pivot point P of the joint member 16 coincides with the axis of the input shaft 12, the input shaft 12 and the swing shaft 15 rotate concentrically. Joint member 1
6 does not swing from side to side, and tie rods 18, 18 are also stationary. Therefore, only the front wheels 7, 7 are steered, and the rear wheels 20, 20 are not steered at all.

On the other hand, when the vehicle speed is low, less than the set value d ₁ (FIG. 6), the computer 31 drives the motor 29 in accordance with the vehicle speed signal from the vehicle speed sensor 32 to adjust the position of the slider 27 as shown in FIG. 3b. Set it in the forward position. When the slider 27 is in the forward position, the swing shaft 15 tilts downward and the pivot point P is offset (eccentric) by _e1 downward from the axis of the input shaft 12, so the joint member 16 is aligned with the input shaft 1.
The rear wheel tie rods 18, 18 are swung left and right in response to the rotation of the front wheel tie rods 5, 5 in the opposite direction to the front wheel tie rods 5, 5. Therefore, the rear wheels 20, 20 are the front wheels 7,
7, and the steering angle ratio of the front and rear wheels changes continuously in accordance with the vehicle speed.

When the vehicle speed exceeds the set value d ₁ (FIG. 6), the computer 31 reverses the motor 29 in accordance with the vehicle speed at that time, and moves the slider 27 backward as shown in FIG. 3c. As the slider 27 retreats, the swing shaft 15 tilts upward, and the pivot point P is offset upward by e ₂ from the axis of the input shaft 12. Therefore, the joint member 16
The rear wheel tie rod 1 swings left and right according to the rotation of the rear wheel.
8 and 18 in the same direction as the front wheel tie rods 5 and 5. Therefore, the rear wheels 20, 20 are steered in the same phase as the front wheels 7, 7, and the steering angle ratio of the front and rear wheels also changes continuously in accordance with the vehicle speed.

Next, the main structure of the present invention will be explained with reference to FIGS. 4 to 6. Figure 4 is a configuration diagram of the main parts.
Fig. 5 is a functional block diagram of Fig. 4, and Fig. 6 is a functional block diagram of Fig. 5.
It is a steering angle ratio output characteristic diagram in the figure.

First, in FIG. 4, reference numeral 34 is a steering angle ratio (or rear wheel steering angle, the same shall apply hereinafter) manual selection switch, which is configured by arranging a plurality of push buttons 35a, 35b, etc., and is mounted on the instrument panel inside the vehicle. It is arranged so that the driver can operate it manually. This selection switch 34 is connected to the computer 31, and the selection result of the steering angle ratio selected by the selection switch 34 is input to the computer 31.

Further, a shift position detection sensor 37 is disposed near the lower part of the speed change lever 36, so as to be able to detect the shift position of the speed change lever 36. In the illustrated embodiment, the shift position detection sensor 37 comprises a limit switch located at shift positions other than "low" and "back". However, the configuration of the sensor is not limited to the above; switches may be provided at all shift positions, or switches may be provided at "low", "back", and "neutral" positions, and the switches themselves are not limited to mechanical limit switches. It may be of any type, such as an optical sensor. When an automatic transmission is used, such a sensor can be disposed inside the automatic transmission to similarly detect the shift state of the transmission gear.

Further, an alarm buzzer 38 is provided at a suitable location on the instrument panel, and the alarm buzzer 38 is connected to the computer 31. Instead of such a warning buzzer, a warning lamp may be installed at a position visible to the driver, or a warning buzzer and a warning lamp may be used together.

Next, the manual selection function of the steering angle ratio in the computer 31 will be explained with reference to FIG.

First, the normal operation (auto operation) in which the steering angle ratio automatically changes depending on the vehicle speed will be explained. This is selected by pressing the first push button 35a of the selection switch 34. As described above, the vehicle speed signal detected by the vehicle speed sensor 32 is input to the computer 31, and is converted into steering angle ratio data _Ka corresponding to the vehicle speed by the conversion process a. On the other hand, the position sensor 33 outputs actual steering angle ratio data.
K _b is obtained, and both steering angle ratio data Ka _and K _b are subjected to comparative calculation processing to obtain necessary steering angle ratio correction information b ₁ . On the other hand, since the above-mentioned automatic operation _AT is selected in the selection switch 34, the above-mentioned correction information b ₁ is directly transferred to the computer 3 by the selection processing c.
1 and is supplied to the motor 29 via the output device 37 with a correction control signal S ₁ for changing the steering angle ratio to a required value according to the vehicle speed.

On the other hand, predetermined steering angle ratio information D is stored in the storage device of the computer 31. This information may include, for example, a plurality of steering angle ratio data K ₁ having arbitrary sizes,
It consists of K ₂ , K ₃ , ...K _o . Then, in the selection switch 34, if an arbitrary push button other than the push button 35a, for example the push button 35b, is pressed, the steering angle ratio data K1 is read out from the steering angle ratio information ₂ , and this is transferred to the position sensor 33. The correction information _b2 is obtained by comparison with the steering angle ratio data _Kb from .

On the other hand, in the selection process c, the selection switch 34
If a pushbutton other than the auto-operation A _T is pressed, this is received, the output of the modification information b ₁ is stopped, and the modification information b ₂ is selected to be output. This causes the modified control signal _S2 to be sent to the output device 39.
is supplied to the motor 29, and the steering angle ratio of the rear wheels is K ₁
is set to

This operation is the same for the other pushbuttons 35b, 35a..., and the driver presses the selection switch 34.
At any steering angle ratio K ₁ , K ₂ , K ₃ ,... shown in Fig. 6,
K _o can be selected manually.

On the other hand, the computer 31 executes a determination process based on the shift position signal obtained from the shift position sensor 37 and the selection state in the selection process C. In this determination process, it is determined whether the shift position is a low speed position, that is, one of "low", "back", and "neutral". If manual switching is performed even when the shift position is at a high speed position other than the low speed position, an alarm buzzer 38 is activated via the output device 40.
activates to alert the driver.

That is, in a state where the manual selection of the steering angle ratio is being performed by the manual changeover switch 34,
When the shift position is shifted up to a high speed position, an alarm buzzer 38 is activated to prompt the driver to confirm the appropriateness of the manual switching setting and cancel it or reduce the vehicle speed.

Note that various processes in the computer 31 may be executed by a predetermined control program (software) stored in the computer 31, for example, in a storage device.

In the above embodiment, the on-vehicle computer 31 is used, but other electrical circuits and mechanical configurations having the same functions may be used.

Although the steering angle ratio of the front and rear wheels can be manually selected using the position sensor 33 and the manual selection switch 34, the rear wheel steering angle may also be selected in the same manner.

Further, the present invention is not limited to the above-mentioned embodiments, and may include a front and rear wheel steering device that hydraulically controls front and rear wheels and transmits front wheel steering angle information using hydraulic pressure, or a front and rear wheel steering device that transmits front wheel steering angle information to the computer 31 as an electrical signal. The present invention can be similarly applied to front and rear wheel steering devices, etc.

<Effect> As described above, according to the present invention, a desired steering angle ratio can be set regardless of the vehicle speed, etc. in a vehicle front and rear wheel steering device, etc., which can vary the steering angle ratio of the rear wheels to the front wheels according to the vehicle speed, etc. It improves the maneuverability of the vehicle by allowing manual changes to be made at will, and also encourages confirmation during medium and high speeds where the appropriateness of manual selection may be a problem, making it possible to change the manual when manual operation is not required. This has the effect of preventing the driver from making a selection and avoiding situations where the driver is faced with unexpected maneuvering responsiveness of the vehicle.

[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. FIG. 2 is an enlarged perspective view of the rear wheel steering system. FIGS. 3a, 3b, and 3c are cutaway side views showing the operating principle of the rear wheel steering system. FIG. 4 is a block diagram of the main parts. FIG. 5 is a functional block diagram of FIG. 4. FIG. 6 is a steering angle ratio output characteristic diagram in FIG. 5. 1...Handle, 2...Handle shaft, 3...Gear box, 4...Rack shaft, 5...Tie rod, 6...Knuckle arm, 7...Front wheel, 8...
Pinion shaft, 9... Universal joint, 10... Linkage shaft, 11... Universal joint, 12... Input shaft, 13
...bearing bracket, 14...clevis, 15...
... Swing shaft, 16 ... Joint member, 17 ... Ball joint, 18 ... Tie rod, 19 ... Knuckle arm, 20 ... Rear wheel, 21, 22 ... Link, 2
3... Bracket, 25... Arm, 26... Link, 27... Slider, 28... Ball screw mechanism, 29... Motor, 30... Output shaft, 3
1... Computer, 32... Vehicle speed sensor, 33
...Position sensor, 34...Selection switch, 35a
~35d...Push button, 36...Speed lever, 3
7...Shift position sensor, 38...Alarm buzzer,
39, 40... Output device.

Claims (1)

[Scope of Claims] 1. In a vehicle front and rear wheel steering device that variably controls the rear wheel steering angle according to certain conditions, one or more preset steering angle ratio information or rear wheel steering angle is provided. information, a manual switching means for selecting the steering angle ratio information or rear wheel steering angle information and realizing a steering angle ratio or rear wheel steering angle corresponding to the selected information, and detecting a shift position of a transmission lever. 1. A front and rear wheel steering system for a vehicle, comprising: warning generating means for generating a warning when the shift position is shifted up to a high speed position with manual switching selected. 2. The front and rear wheel steering system for a vehicle according to claim 1, wherein the warning generating means utilizes a light emitting means such as a lamp. 3. The front and rear wheel steering system for a vehicle according to claim 1, wherein the warning generating means utilizes a sounding means such as a buzzer.