JPH0366188B2 - - Google Patents

Description

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

The present applicant has already proposed a vehicle steering system (patent application No. 57) that steers the rear wheels in conjunction with the steering of the front wheels and varies the steering angle ratio of the rear wheels to the front wheels in accordance with the vehicle speed.
-134888 (see JP-A No. 59-26363), etc.). An overview of this device will be explained. 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 contrary, the rear wheels are steered in the same phase as the front wheels. As shown by D in Fig. 9, this steering angle ratio becomes a continuous function of the vehicle speed, and if the vehicle speed becomes higher than a predetermined vehicle speed d as a boundary, the steering angle ratio becomes positive, that is, in the same phase. As the vehicle speed becomes lower, the steering angle ratio becomes negative, that is, in reverse phase, and the steering angle ratio is continuously controlled in accordance with this function curve D to achieve both the functions of the steering system 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 entering a garage, driving on narrow curved roads, making U-turns, etc. On the other hand, at high speeds, maneuvering responsiveness can be dramatically improved.

However, when parallel parking at low speeds or pulling closer in a narrow space, it is often easier to steer the vehicle if the front and rear wheels are steered in the same phase rather than in opposite phases.

Therefore, at the same time as this application, the present applicant proposed a front and rear wheel steering system for a vehicle that is equipped with a manual switching means and can arbitrarily change the steering angle ratio of the rear wheels to the front wheels (or the rear wheel steering angle) regardless of the vehicle speed, etc. is proposed.

By the way, manual setting is only necessary at low speeds, as mentioned above. Therefore, a situation may arise in which the driver continues to drive the vehicle at a higher speed with the manual setting. In this case, a problem arises in which the driver's steering effort becomes unnecessarily large under certain driving environments, such as when passing through a curve with a small turning radius, the steering wheel must be rotated considerably.

The present invention aims to eliminate such problems, and its purpose is to make it possible to arbitrarily change the steering angle ratio of the rear wheels to the front wheels, regardless of the vehicle speed or the amount of front wheel turning. Even if the driver accidentally tries to increase the vehicle speed, the system prevents the vehicle from increasing above a certain speed to prevent loss of maneuverability at medium and high speeds.

In order to achieve the above object, the present invention is applied to 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, and the main component thereof is one or more preset steering angles. ratio (or rear wheel steering angle) information, a manual switching means that selects this steering angle ratio (or rear wheel steering angle) information and changes it to an arbitrary steering angle ratio (or rear wheel steering angle), and a vehicle speed at the time of manual setting. The first aspect of the invention is characterized in that the first invention is equipped with an alarm generating means that detects the vehicle speed and issues an alarm using a lamp or a buzzer when the vehicle speed exceeds a certain speed, thereby reminding the driver not to increase the vehicle speed above a certain speed, In addition, it is also equipped with a vehicle speed control means that uses, for example, a throttle control actuator to detect the vehicle speed during manual setting and control the vehicle speed to decrease or keep it constant when the vehicle speed exceeds a certain speed, so that the vehicle speed does not rise above a certain speed. The second thing is to suppress
Features of the invention.

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, FIGS.
The configuration and operation of the front and rear wheel steering device will be explained with reference to the 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. The handle shaft 2 of the handle 1 is built into a rack and pinion 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 to each other, 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 universal joint 14.
A joint member 16 is loosely fitted in the middle of this swing shaft 15. A tie rod 1 is connected to the left and right ends of this joint member 16 via ball joints 17, 17.
8 and 18 are connected, and the joint member 16 is swingably supported by links 21 and 22 and a bracket 23 toward the vehicle body. Further, knuckle arms 19, 19 supporting rear wheels 20, 20 are connected to the outer ends of both tie rods 18, 18.

An arm 25 is provided at the rear end of the swing shaft 15.
is fixed perpendicular to the axis, a link 26 is pivotally attached to the lower end of this arm 25, and a slider 27 is pivotally attached to the rear end of the link 26. This slider 27
As shown in FIG. 3, there is a ball screw mechanism 28.
The output shaft 30 of the motor 29 is screwed together through the input shaft 12, and the output shaft 30 is coaxial with the input shaft 12 and arranged rearward, thereby fixing the motor 29 to the vehicle body.

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
Since the pivot shaft 15 rotates concentrically, the joint member 16 does not swing left or right, and the tie rods 18, 1
8 is also immovable. 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), the computer 31 receives a signal from the vehicle speed sensor 32 and makes a judgment, controls the rotation of the motor 29 according to the vehicle speed at that time, and moves the slider 27 forward as shown in FIG. 3b. urge As the slider 27 moves forward, the swing shaft 15 tilts downward, and the pivot point p is offset (eccentrically) by _e1 downward from the axis of the input shaft 12, so the joint member 16 swings left and right, and The tie rods 18, 18 are moved in the opposite direction to the front wheel tie rods 5, 5, so that the rear wheels 20, 20 are steered in a phase opposite to that of the front wheels 7, 7. At this time, the steering angle ratio of the front and rear wheels changes continuously in accordance with the vehicle speed.

Further, when the vehicle speed exceeds a set value, the computer 31 causes the motor 29 to rotate in reverse according to the vehicle speed at that time, and the slider 27 is moved backward as shown in FIG. 3c. This retreat of the slider 27 causes the swing shaft 15 to tilt upward, and the pivot point p is offset upward by e ₂ from the axis of the input shaft 12, so that the rear wheel tie rods 18, 18 are aligned with the front wheel tie rods 5, 5. The rear wheels 20, 20 are moved in the same direction, and the rear wheels 20, 20 are therefore steered in the same phase as the front wheels 7, 7. At this time, the steering angle ratio of the front and rear wheels also changes continuously in accordance with the vehicle speed.

Next, an embodiment according to the first invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram of main parts, and FIG. 5 is a functional block diagram of FIG. 4. In addition, in FIGS. 4 and 5, the same parts as in FIGS. 1 to 3 are given the same reference numerals to clarify the structure. First, in FIG. 4, reference numeral 34 is a manual selection switch for the steering angle ratio (or rear wheel steering angle, the same applies hereinafter), which is configured by arranging a plurality of push buttons 35a, 35b, etc. It is arranged on the panel 36 so that the driver can manually operate it. This selection switch 34 is connected to the computer 31, and the selection switch 34 is connected to the computer 31.
The selection result of the steering angle ratio selected in step 4 is input to the computer 31. On the other hand, a warning lamp 37 is provided at a predetermined position on the instrument panel 36 that is visible to the driver, and a warning buzzer 38 is provided at a predetermined position in the vehicle interior. Connect to 31. In addition, this lamp 37 or buzzer 38
can be either one.

Next, the functions of the computer shown in FIG. 4 will be explained with reference to FIG.

First, the normal operation (auto operation) in which the steering angle ratio is automatically varied in accordance with the vehicle speed is selected, for example, by pressing the first push button 35a of the selection switch 34. As mentioned above, the vehicle speed sensor 32
The detected vehicle speed signal is input to the computer 31, and converted into steering angle ratio data Ka corresponding to the vehicle speed by a conversion process (a). On the other hand, actual steering angle ratio data Kb is obtained from the position sensor 33, and each steering angle ratio data Ka and Kb are subjected to a comparison calculation process to obtain necessary steering angle ratio correction information _b1 . On the other hand, since the selection switch 34 selects the above-mentioned automatic operation _AT ,
Through the selection process C, the correction information b ₁ is output as is from the computer 31, and a correction control signal S ₁ is supplied to the motor 29 via the output device 39 to change the steering angle ratio to a required value according to the vehicle speed.

Next, manual operation will be explained. Predetermined steering angle ratio information is set and stored in the storage device of the computer 31. This information consists of multiple pieces of steering angle ratio data K ₁ , K ₂ , K ₃ , K _o having arbitrary sizes.
Consisting of Then, in the selection switch 34, by pressing any push button other than the push button 35a, for example, the push button 35b, the steering angle ratio data _K1 is read out from the steering angle ratio information.
The steering angle ratio data Kb is compared with the steering angle ratio data Kb from ₁ to obtain correction information b2. On the other hand, in the selection process C, if a pushbutton other than auto-activation A _T is pressed on the selection switch 34, in response to this, the output of the modification information b ₁ is stopped and the modification information b ₂ is output. select. As a result, the output device 39 supplies the corrected control signal _S2 to the motor 29, and sets the steering angle ratio of the rear wheels to _K1 . This is the other pushbutton 3
5b, 35c..., and the driver manually selects and sets any steering angle ratio _K1 , _K2 , _K3 ... _Ko shown in FIG. 8 using the selection switch 34. I can do it.

In addition, the computer 31 compares the vehicle speed signal (actual measurement value) detected from the vehicle speed sensor 32 with a preset constant vehicle speed (reference value T), and determines whether or not the actual measurement value is greater than or equal to the reference value T. Execute the judgment process to make the determination. If the vehicle speed is above the reference value T, that is, above a certain vehicle speed, an output signal is supplied to the output device 40, and the output device 40 lights the warning lamp 37 or lights it intermittently if necessary. Sound the alarm buzzer 38,
Inform the driver of the condition. Note that such judgment processing is executed only when manual settings are made, and in normal automatic operation A _T , the output device 40
The output signal for actuating is always zero.

Next, an embodiment according to the second invention will be described with reference to FIGS. 6 to 8. 6 is a block diagram of main parts, FIG. 7 is a sectional block diagram of the actuator shown in FIG. 6, and FIG. 8 is a functional block diagram of FIG. 6. Note that in FIGS. 6 to 8, the same parts as in FIGS. 4 and 5 are given the same reference numerals to clarify the structure, and detailed explanation thereof will be omitted.
First, in FIG. 6, reference numeral 41 is an automatic constant speed driving device which maintains the vehicle speed at a constant speed on a highway or the like without pressing the accelerator pedal. The device 41 includes a throttle control actuator 42 which receives a signal S ₃ from a control unit (not shown) as is clear from FIG.
Vacuum valve 4 for acceleration depending on (energization time)
3. Open and close the vent valve 44 for deceleration, introduce the negative pressure of the engine or the atmosphere into the actuator negative pressure chamber P, actuate the diaphragm 45, and act on the pedal link connected to the diaphragm 45 to adjust the throttle opening. It has the function of controlling Note that arrow _H1 indicates an atmospheric path, and arrow _H2 indicates a negative pressure path. Vacuum valve 43 introduces negative pressure while energized, and shuts off the negative pressure when energized. The vent valve 44 shuts off the atmosphere and maintains the negative pressure in the negative pressure chamber P while energized, and introduces the atmosphere when the energization is cut off. Also, 46 is a safety valve that shuts off the atmosphere when energized and lets in the atmosphere when it is not energized, which accelerates deceleration when canceling. In addition, numeral 47 is a vacuum accumulator, 48 is a filter, 49 is a check valve, 50 is a cab insulator, and 51 is a pedal link coupling portion.

In this embodiment, an output control device 52 is connected to the vacuum valve 43 and vent valve 44 of the actuator 42 to drive each valve 43 and 44, and the computer 31 is connected to the output control device 52 to perform necessary operations. Control signal S ₄
send. Thus, the computer 31 operates the actuator 42 to control the throttle opening, that is, the vehicle speed.

Next, the control function of the actuator 42 in the computer 31 will be explained with reference to FIG. The automatic operation and manual operation explained in FIG. 5 are exactly the same in FIG. 7, and detailed explanation thereof will be omitted.

Now, assume that the setting is manually set using the manual changeover switch 34. In this case, the computer 31 compares the vehicle speed signal (actual measurement value) detected from the vehicle speed sensor 32 with a preset constant vehicle speed (reference value Q), and determines whether or not the actual measurement value is greater than or equal to the reference value Q. Execute the judgment process. If the vehicle speed is equal to or higher than the reference value Q, that is, equal to or higher than a certain vehicle speed, the control signal _S4 is outputted and supplied to the output control device 52, and the actuator 4
By controlling the throttle opening as described above, the vehicle speed is reduced and maintained constant. As a result, the vehicle speed is suppressed so that it does not exceed a certain vehicle speed.

In each embodiment, various processes in the computer 31 are executed by a predetermined control program (software) stored in the computer 31. Furthermore, in addition to the on-vehicle computer 31 as described above, it may also be configured with an electric circuit having a combination of the same functions.

Moreover, although the steering angle ratio of the front and rear wheels can be manually selected using the position sensor 33, the rear wheel steering angle may be similarly selected.

Further, the present invention is not limited to the 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 transmits the front wheel steering angle as an electrical signal to the computer 31. The present invention can be similarly applied to front and rear wheel steering devices, etc.

As described above, the front and rear wheel steering device for a vehicle according to the present invention can arbitrarily change the steering angle ratio of the rear wheels to the front wheels regardless of the vehicle speed, etc., and can easily perform parallel parking or side-to-side parking at low speeds, and can improve the steering angle of the rear wheels to the front wheels. In addition to the basic effect of greatly improving maneuverability,
Even if the driver attempts to increase the vehicle speed with manual settings, the warning generating means will alert the driver not to increase the vehicle speed above a certain speed (first invention), or the vehicle speed control means will alert the driver not to increase the speed above a certain speed. In order to suppress it from increasing (second invention),
There is no loss in maneuvering response at medium to high speeds.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the general basic structure of a vehicle equipped with a front and rear wheel steering system, Figure 2 is an enlarged perspective view of the rear wheel steering system, and Figures 3a, b, and c are cutaway side views showing its operating principle. 4 is a block diagram of the main parts according to the first invention, FIG. 5 is a functional block diagram of FIG. 4, FIG. 6 is a block diagram of the main parts according to the second invention, and FIG. 8 is a functional block diagram of the actuator shown in FIG. 6, and FIG. 9 is a steering angle ratio output characteristic diagram in FIG. 5 or 7. In the drawing, 31 is an on-vehicle computer, 32 is a vehicle speed sensor, 33 is a position sensor, 34 is a manual selection switch, 35a, 35b, 35c... are push buttons, 37 is an alarm lamp, 38 is an alarm buzzer,
40 is an output device, 42 is a throttle control actuator, 52 is an output control device, C is a selection process, D is steering angle ratio information, E is a comparison calculation process, F,
li is a judgment process.

Claims (1)

[Scope of Claims] 1. A front and rear wheel steering system for a vehicle capable of variably controlling the steering angle of the rear wheels relative to the front wheels, comprising one or more preset steering angle ratios (or rear wheel steering angles) information and the steering angle of the rear wheels relative to the front wheels. Angle ratio (or rear wheel steering angle)
It is characterized by comprising a manual switching means that selects information and changes it to an arbitrary steering angle ratio (or rear wheel steering angle), and an alarm generation means that detects the vehicle speed and issues an alarm when the vehicle speed exceeds a certain value at the time of manual setting. Front and rear wheel steering system for vehicles. 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. 4. In a front and rear wheel steering system of a vehicle that can variably control the steering angle of the rear wheels relative to the front wheels, one or more preset steering angle ratios (or rear wheel steering angles) information and this steering angle ratio (or rear wheel steering angles) are used. rudder angle)
A manual switching means that selects information and changes it to an arbitrary steering angle ratio (or rear wheel steering angle), and a vehicle speed control means that detects the vehicle speed at the time of manual setting and controls the vehicle speed to be reduced or kept constant when the vehicle speed is higher than a certain speed. A front and rear wheel steering device for a vehicle, comprising: 5. The front and rear wheel steering system for a vehicle according to claim 4, wherein the vehicle speed control means is controlled by a throttle controller actuator.