JPS6067273A - Four-wheel steering device of car - Google Patents

Abstract

PURPOSE:To reduce the error ratio and improve followability by moving rear wheels by little by means of a rear wheel steering device when the front wheel steering speed is low at a high car speed and moving them faster when the front wheel steering speed in high at a low car speed. CONSTITUTION:A steering device 2 steering front wheels 1 and a rear wheel steering device 4 steering rear wheels 3 are provided, and the rear wheel steering device 4 is driven by a pulse motor 5. The steering angle of the steering handle 6 of the steering device 2 is detected by a steering angle sensor 7, and a control means fed with at least the signal of this steering angle sensor 7 feeds a control signal in response to the front wheel steering angle to the pulse motor 5. A step angle setting means outputs a signal increasing the step angle of the pulse motor when the car speed is low and relatively decreasing the step angle of the pulse motor 5 when the car speed is high to the pulse motor 5 via the control means.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides four-wheel steering for vehicles such as automobiles in which steering control is applied to the C rear wheels in response to the steering of the J5C front wheels. It is related to equipment.

(Prior Art) Conventionally, a four-wheel steering system for a vehicle of this scale has been used, for example, as disclosed in Japanese Patent Application Laid-Open No. Steer the rear wheels by 7)) J'
[7] By controlling the operation of the hydraulic actuator according to the front wheel steering angle and vehicle speed, the rear wheel steering angle characteristic relative to the front wheel steering angle can be adjusted to the vehicle speed. A device is known in which the temperature is changed depending on the situation. With this four-wheel steering system, for example, at low speeds, the rear wheels are steered in the opposite direction (opposite phase) to the front wheels, thereby improving turning performance and reducing the minimum turning radius. Sometimes, it is possible to smoothly steer the rear wheels in the same direction (same (1/phase)) as the front wheels.

However, in addition to performing four-wheel steering as described above, the conventional method is used to control the position of the two-way machine - 1" J X - Y block - etc., and the responsiveness is When a pulse motor that is capable of Normally, when controlling the above-mentioned pulse Tanabata, the step angle (for example, 0
．． 9°/5tep) is kept constant and the number of pulses of the drive pulse signal, that is, the number of steps, is varied to control the movement m. There is a limit to the response speed, for example 1 per second.
About 500 sd is the limit of what is normally used. Therefore, in order to increase the speed of the pulse motor, the step angle can be increased, but if the step angle is too large (for example, 3.6°/5
p) is that at low speed +1i'i where the amount of change in steering (front wheel turning speed) is relatively large, the rotational speed of the pulse motor is large and it is possible to improve the rear wheel turning delay, but when the steering change ii1 (
At high speeds when the front wheel steering speed (front wheel steering speed) is relatively small, the rear wheel steering angle, which is moved in one step of the pulse motor, becomes clumsy and the control accuracy decreases, requiring particularly high precision control4.
There is an e in -b that is inappropriate for wheel steering equipment.

However, in order to solve the above problem 1711, a pulse motor with a small step angle C1 and a high number of steps per second is used. There are problems such as an increase in Fi power.

(Purpose of the Invention) In view of the above circumstances, Akira has discovered that it is possible to easily change the step angle by changing the excitation method, for example, by changing the excitation method. %
When J3 is in the operating state at t, the high speed is 0. Blasphemy is slow +1.
Since the steering m of the steering wheel is smaller than that of 'i', the steering wheel steering table [r? The movement of the rear wheels is reduced in small increments at 8th gear 1j''T, where the front wheel steering speed is low, to reduce the error ratio and make ^tlifα match the self-speed value, while at low speeds where the front wheel steering speed 11 is high. The purpose is to provide a four-wheel steering system for vehicles with improved control performance that sometimes increases speed and improves follow-up performance to eliminate the occurrence of steering wheel failures. Guaru.

(Structure of the Invention) Figure 11 of the nail is the entire structure 1 for clearly showing the structure of the present invention (111).
i, i is the cause.

The four-wheel steering device fY i,'l of the present invention is equipped with a steering device 2 for steering the front wheels 1, a rear wheel steering device 4 for steering the rear wheels 3, and the rear wheel steering device /l is a pulse motor. 5. The steering angle of the steering handle 6 of the steering device 2 is detected by the steering angle sensor 2X, and the control means to which at least the signal of the steering angle sensor 7 is manually input sends a control signal corresponding to the front wheel steering angle to the pulse motor 5. I'll send it out. Further, when the vehicle speed is 1:N low, the vehicle speed sensor 8 detects that the vehicle speed is 1:N low, and based on the output of the vehicle speed sensor 8, the step angle setting means generates a signal that relatively reduces the step angle of the pulse motor 5 when the vehicle speed is high. The signal is output to the pulse motor 5 via the control means.

The height of the vehicle speed is detected, and when the IN speed is low, the step angle of the pulse tanabata is set to less than 6. When the vehicle speed or restraint is detected, the step angle of the pulse motor is made smaller. The low speed 11.1 also reduces the rear wheel steering speed to improve followability.17Shi eliminates the rear wheel steering delay, and at high speeds when the front wheel steering speed is small, the rear wheel steering angle is reduced. It is possible to reduce the error with the target comb and steering angle in small steps, perform highly accurate control over the entire range, and fully control the characteristics of the four-wheel steering system. That is -C monkey.

(Example) Examples of the present invention will be described below with reference to FIGS. 2 to 5j.

As shown in FIG. 2, the steering device 2 for steering the front wheels '1.1 of the No. ．． ! Hiii 11, etc., transmits the operation of the rattan pinion 11 to the front wheels 1゜1 and steers them.
11''go7F-)--nnno7noIIu7/, IQ1',
'lJ-Kaguchi 414 has been completed.

On the other hand, the wheel steering device 4 that steers the left and right rear wheels 3.3 is
A rear wheel operating rod 14 is held on the vehicle body so as to be movable in the left and right direction, and left and right knuckle arms 16 are connected to the left and right ends of the rear wheel operating rod 14 via tie rods 15 and 15, respectively. 16, and the rear wheels 3.3 are steered by the axial movement of the rear wheel operating rod 14. A rack 17 is formed on the rear wheel operating rod 14.
The pinion 18 meshing with the rack 17 is connected to the pulse motor 5.
A pair of bevel gears 19, 20J5 and pinion shaft 21
By being rotated through the pulse motor 5, the rear wheel 3J3 is steered in accordance with the direction and amount of rotation of the pulse motor 5.

Further, the rear wheel operating rod 14 is connected to a power cylinder 22.
through the left and right hydraulic chambers 22 inside the power cylinder 22.
A piston 23 partitioning the rear wheel into the rear wheel operating rod 14 is fixed to the rear wheel operating rod 14, and the hydraulic pressure 1ffi22a, 22b is fixed to the rear wheel operating rod 14.
Hydraulic oil v825a led from the control valve 24 installed around the vinyl 11121 is installed in 2b.
, 25F) are connected respectively, and the above controllers 1 to [1
A hydraulic supply passage 2B and a return passage 29 are provided between the oil valve 24 and the oil pump 27.

Here, the above-mentioned 21 control valve 27! I is operated in response to the rotational force applied to the pinion shaft 21 during the rotation of the pulse Tanabata 5, and is operated from the oil pump 27 to the hydraulic pressure supply passage 28.
According to the direction of the rotational force, the hydraulic pressure supplied through Δ is introduced into the hydraulic pressure chamber 22b or 22b of either one of the power cylinders 22, and the other hydraulic pressure chamber 22b or 22
The hydraulic oil in a is returned to the oil pump 27 via the return passage 29. Therefore, the pulse motor 5 rotates the bevel gear 19°20, the pinion shaft 21,
When the rear wheel operating rod 14 is moved in the axial direction via the pinion 18 and the rack 17, is it introduced into the power cylinder 22? The 111 pressure operates the rear wheel via the piston 23 and assists the movement of the shaft 14.

The pulse motor 5 is connected to the control pin output from the controller 30 via the driver 31 (operation control +
be done. The controllers 1 to 30 are provided with a medium speed signal output from the medium speed sensor 8 and a steering angle sensor (from J7) that detects the steering angle of the steering wheel 6 that goes to the steering decoy 2. The rear wheel steering amount is detected from the steering angle signal and the operation amount of the pulse motor 5 which is input to the contact wheel steering device 4. The rear wheel steering angle is determined by the rear wheel steering angle reduction from the sensor 33, the battery power source B and the ignition. Signal 1 (l) is input.

Also, this 11-1 roller 30 has a meter display 34.
is connected and the -ζ steering status is displayed.

Next, the configuration of the controller 1-roller 30 will be explained with reference to FIG.

Detection signal d3 of the steering angle sensor 7 J: and vehicle speed sensor 8
The IJI signal indicates the rear wheel turning angle 1iii n part 35 (by manual input, this rear wheel turning angle control part 35 sets the target rear wheel turning angle 0).
r is performed.

In other words, the rear wheel steering angle control unit 35 operates the steering wheel 6 to turn the steering wheel 6 according to the signal from the steering angle sensor 7.
Determine the target rear wheel steering angle θr. This calculation of the rear wheel turning angle θ1' is carried out in such a way that the characteristics of the rear wheel turning angle θ1' with respect to the steering angle θh and the vehicle speed V as shown in FIG.
5. 1) 1 and a3 are excluded according to this characteristic. Here, the rear wheel steering characteristics, which are not shown in FIG.
1 (steering angle OI) exceeds a certain value, the steering angle θ1
1, the rear wheel steering angle θr becomes larger as the steering ratio θ increases.
At r/θ11, the phase increases in the negative direction (the front and rear wheels are steered in opposite directions) - h, high speed (at 11 (, (,
As the steering angle Oh increases, the rear wheel turning angle θ1' increases in the positive direction with a phase of 1iiJ (the front and rear wheels are in the same direction lI: steering state), and as the steering angle exceeds a certain steering angle θ11, the steering ratio increases. This is set so that θr/θ11 is approximately constant. This is in order to achieve this smoothly.

” 2 Rear wheel steering angle calculation part 35 gave 0 Rear wheel steering wheel steering angle a Anri a Actual 11 from a! It compares the rear wheel turning angle θr+ with the rear wheel turning angle θr+, and outputs a signal corresponding to the control illumination Φ according to the width difference hill to the correction pulse light output section 339.

In addition, the vehicle speed signal V in the medium speed range ε3 is transmitted to the second comparator 3).
7, the second comparator 37 compares this vehicle speed V with the setting number from the setting number generating section 38, and when the fit speed V is higher than the setting f1riK, the second comparator 37 compares the vehicle speed V with the setting number from the setting number generating section 38.
A step angle signal of high level or low level is output to the driver 3'1, and the step angle of the pulse motor 5 can be adjusted by changing ＾ Small at high speed (1 step up 0.9°), large at low speed (1 step 1.8°)
) is switched and driven.

The correction pulse generator 39 outputs a drive pulse signal of a predetermined frequency to the driver 31 to switch the rotation direction corresponding to the rotation direction of the pulse motor 5 according to the positive or negative of Or - Or'. Hako No. 16 J3 J
: Receives a step angle signal corresponding to the medium speed V from the second comparator 37, converts it into a drive pulse signal for driving the pulse motor 5, and outputs it to the C-pulse septator 5, thereby generating a 1;1 contact wheel rotation. −
The rear wheel steering device 4 is driven so that the steering angle is 01.

Jl, the above drive pulse signal is low speed 1), Jj is the maximum steering angle speed of the steering wheel (lO (approximately 760°/S
) and above this: IL! The number of pulses required to drive -95 is to pulse the steering to the maximum value (approximately 20 degrees) of the rear wheel steering angle θ1゛ (approximately 20 degrees) based on the characteristics shown in Figure 4. and the step angle signal becomes condensed, and at high speeds, both the steering wheel angular velocity J and the rear wheel turning angle θr shown in FIG. Pulse motor 5 evenly
The number of pulses and the step angle signal for driving are the sum of the signals.

Next, the operation of the controller roller 30 of the above embodiment will be explained using the flow 17-1- shown in FIG.

In the example shown in Fig. 5, unlike Fig. 3, the rear wheel steering angle lens →
This figure shows the case where the A-turn control is performed on the actually measured rear wheel turning angle signal of No. 33 without human power.

According to the routine in FIG. 5, star 1-L, 'c1
Sysram Inishi 1? After rice (step '1 in Figure 5), read the steering angle θ11 from the steering angle sensor 7 and the ZD speed V from the speed Vε3 (
+)2).

Illll whether this steering angle θ11 is Oo! 7i L/
(P3), )113S, the rear wheel steering angle θ1゛ is corrected to Oo (P4), while in the case of No, the steering angle θ11J3 and the vehicle speed V are used, and the characteristics shown in Fig. 4 are corrected to J. , extracts the target rear wheel turning angle θ1゛ which is registered in advance (1
]5).

Zoshi-(, low speed 1 where vehicle speed V is smaller than setting 1 + fj K
1.1 Judgment 1) (p(i), YES (low speed), set the step angle to 1.8°/5te
output J (Pl), while No (high speed)
Next, reduce the step angle to 0.9°/St(!p
A signal is output to the driver 31 (P8). Next, step 1]! ) so that the v1 wheel steering angle θr matches the previously calculated rear wheel steering angle θr', (θr−θ
I゛' l = 0 The number of pulses and rotation direction is nl [
and output a predetermined drive pulse to the driver 311]9
), the current rear wheel steering angle Or is stored as the previous rear wheel steering angle θr1 According to the above embodiment, when the vehicle speed V is low,
While setting the step angle of the pulse motor 5 to a large angle to eliminate the tendency of the rear wheels 3 to turn, when the vehicle speed V is high, the step angle is reduced to make the movement of the first wheel 3 small and the entire steering wheel 3 is turned in small increments. J, rear wheel steering RI with Jl C precision in the area! Ill can do it.

In addition, although the above-mentioned embodiment J shown in FIG. This is because large II and Y will result in a delay in response to the output of C when feedback control is executed, but the present invention (Jl)
For example, the reference position of the rear wheels 3 may be corrected only for the steering angular velocity to eliminate the accumulation of control errors.
It is also applicable to a system in which the steering angle of the rear wheels is constantly feedback-controlled.

On the other hand, in the above embodiment, the steering of the rear @3 is assisted by the oil I in the rear wheel steering I. The asynut configuration may be adopted.

In addition, as described above, the step angle is relatively changed depending on the vehicle speed, and the drive pulse frequency of the pulse motor 5 is made variable corresponding to this medium speed. Better control can be achieved by reducing the step angle by 8 or at the same time lowering the drive pulse frequency.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a four-wheel steering system for 11 vehicles to clearly demonstrate the structure of the present invention. 3 is a block diagram of the controller, FIG. 4 is a characteristic diagram showing an example of the rear wheel steerability 11 set in the controller, and FIG. This is a flowchart showing the flow of rear wheel steering control. 1...Front wheel 2...Steering device u3...Rear wheel 4 stomach...Rear wheel steering device 5...
...Pulse motor 6 ... Steering handle 7 ... Steering angle sensor υ 8 ... Vehicle speed range 30 ... Controller

Claims (1)

[Claims] (1) A steering device that steers the front wheels, a rear wheel steering device that steers the rear wheels, a pulse motor that drives the rear wheel ψλ Tateha device, and a steering angle of the steering wheel of the steering device. The rudder angle sensor to be detected and the rudder angle sensor (both input the signal from the rudder angle sensor 9 and adjust it according to the front wheel turning angle)
A control means for sending the i'l ill signal to the pulse motor, a vehicle speed sensor for detecting the height of the vehicle speed, and a relatively small step angle of the high-speed pulse motor based on the output of this vehicle speed sensor I. A turning step angle setting means is provided (
] A four-wheel steering device for a vehicle characterized by the fact that: