JPH037266Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a rear steering control device that changes the steering angle of the rear wheels in steps according to the steering angle of the front wheels, that is, the steering angle of the steering wheel.

It is desired to improve the turning performance and followability of a front wheel drive vehicle. For this reason, a rear steering control device has been proposed that improves the turning performance of the vehicle by steering the rear wheels in the opposite direction by a predetermined angle when the front wheels are steered by a predetermined angle. However, in such a rear steering control device, when the predetermined angle at which the rear wheels are steered becomes large, the shock when the rear wheels are steered or returned to their original position becomes large, and the steering angle becomes too large for the occupants. However, the drawback was that it felt a lot more strange.

This idea was made in view of the above points,
The purpose is to provide a rear steering control device that can prevent hunting of the rear wheel steering angle and realize stable control when controlling the rear wheel steering angle in response to front wheel steering.

Hereinafter, a rear steering control device according to an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view of the rear steering device, and FIG. 2 is a hydraulic circuit diagram showing a neutral state. In FIG. 1, 1 is an electric motor, 2 is a hydraulic pump driven by the electric motor 1, 3 is a reservoir, and 6 is a high-pressure oil path extending from the hydraulic pump 2.
21 and 122 in FIG. 2 are check valves installed in the same voltage oil line 6, and 6' is the high pressure oil line 6 on the upstream side of the check valve 121.
11 is a relief valve provided in the oil passage 6', 111 is an oil passage extending from the downstream of the check valve 121 to the pressure switch 112, and 13 is the check valve 121. If the pressure on the downstream side of the check valve 121 including the accumulator 13 is higher than the pressure on the upstream side of the check valve 121, the pressure from the hydraulic pump 2 will be reduced. Pressure oil shows arrow a → b → c → hydraulic pump 2
It has become a cycle. Further, reference numeral 14 denotes a position switching type control valve that switches and controls the state of supply and discharge of pressure oil to the hydraulic cylinder 24, and the control valve 14 is a second control valve.
As shown in the figure, the high pressure Oil passage 6 has check valve 122 and in-line filter 1
23, the first and second electromagnetic switching valves 15, 1
It is connected to the P port of 6. Further, the low pressure oil passage 6' is connected to the first and second electromagnetic switching valves 15 and 1.
It is connected to the R port of 6. Further, 7a and 7b are oil passages on the side of the second electromagnetic switching valve 16, and the oil passages 7a and 7b are
The first and second check valves 17 and 18 are interposed in a and 7b. Further, 8 and 9 are oil passages on the side of the first electromagnetic switching valve, and 24 in FIGS. 1 and 2 is a rear wheel steering hydraulic cylinder;
As shown in FIG. 2, the cylinder 25 is composed of a cylinder 25 and a piston rod 26, and end plates 25a and 25d are provided at both ends of the cylinder 25, and the middle left side is provided with a cylinder 25 that is connected to the left side and the right side. There is an annular partition wall 25b that partitions the cylinder 25 into two parts, and an annular protrusion 25b that protrudes into the cylinder 25 on the middle right side.
There is a 5c. Further, on the left side of the piston rod 26, which passes through the cylinder 25 and has both ends protruding outside the cylinder 25, there is a piston 26a that partitions the inside of the cylinder 25 on the left side of the annular partition wall 25b into chambers f and g. On the right side of the piston rod 26, there is a large diameter portion 26b, and furthermore, the large diameter portion 26b is located on the right side of the piston rod 26.
6b is provided with an annular groove 26c. Further, 27 is a sliding ring fitted into the piston rod 26 between the partition wall 25b and the large diameter portion 26b so as to be movable in the axial direction, and 28 is a sliding ring between the large diameter portion 26b and the end plate 25d. A sliding ring fitted into the piston rod 26 so as to be movable in the axial direction, 29 a cylinder provided in the cylinder 25 at the annular protrusion 25c portion, and 30 a lock fitted slidably into the cylinder 29. The tip of the locking piece 30 can penetrate the wall of the cylinder 25 and move in and out of the cylinder 25. In addition, 31 is the lock piece 30 and the cylinder body 2.
9 and the bottom of the spring 31.
The lock piece 30 is always biased in the direction of the piston rod 26. Further, the first check valve 17
The flow path 7a on the downstream side of the cylinder 25 is connected to the chamber f of the cylinder 25.
The oil passage 7b downstream of the second check valve 18 is connected to the chamber g of the cylinder 25, and the oil passage 8 downstream of the first electromagnetic switching valve 15 is connected to the chambers h, i of the cylinder 25. The oil passage 9 on the downstream side of the first electromagnetic switching valve 15 is connected to the cylinder 29, and the low pressure oil passage 6' is connected to the cylinder 25 between the sliding rings 20 and 28. ing. Here, 21 is an oil path extending from the oil path 7a on the upstream side of the first check valve 17 to the back of the second check valve 18, and 22 is the oil path on the upstream side of the second check valve 18. The oil passage 23 extends from the oil passage 7b to the back of the first check valve 17, and the oil passage 231 extends from the oil passage 8 on the downstream side of the first electromagnetic switching valve 15. This is an oil passage extending from the oil passage 9 on the downstream side of the switching valve 15. Furthermore, the first
32 and 33 in the figure are the rear wheel steering hydraulic cylinders 2.
Parallel link on the rear wheel side connected to the piston rod 26 of 4, 34 and 35 are the suspension on the rear wheel side,
36 is a handle sensor, 37 is a control device, 38
is the handle. This control device 37 will be described later using FIG. 3.

Next, the operation will be briefly explained. A case where solenoids c and b are excited will be explained.
In this case, the first electromagnetic switching valve 15 operates in the direction of arrow e in FIG. 2 from the neutral position in FIG. As a result, the pressure oil from the hydraulic pump 2 or the accumulator 13 is sent into the cylindrical body 29 via the high pressure oil path 6 → the P port of the first electromagnetic switching valve 15 → the D port → the oil path 9, and the lock piece 30 moves backward against the spring 31, and the tip of the lock piece 30 is connected to the rear wheel steering hydraulic cylinder 25.
The piston rod 26 comes out of the annular groove 26c of the piston rod 26, and the piston rod 26 becomes free. Also,
A part of the pressure oil flowing through the oil passage 9 is sent to the third check valve 19, and the oil passages on the upstream side and the downstream side of the third check valve 19 communicate with each other. The second electromagnetic switching valve 16 also operates in the direction of arrow d from the neutral position in FIG. →Second check valve 18→
The oil is sent to the chamber g of the rear wheel steering hydraulic cylinder 25 via the oil path 7b. On the other hand, a part of the pressure oil flowing through the oil passage 7b on the upstream side of the check valve 18 is sent to the first check valve 17 via the oil passage 22, and the oil on the downstream side of the first check valve 17 is sent to the first check valve 17 via the oil passage 22. The passage 7a and the upstream oil passage 7a communicate with each other, and the oil passages 7a, 7a communicate with the reservoir 3 via the R port of the second electromagnetic switching valve 16 and the low pressure oil passage 6'. Therefore, while the oil in the chamber f is returned to the reservoir 3, the piston rod 26 of the rear wheel steering hydraulic cylinder 25 moves in the direction of arrow d, and the rear wheels are steered to the right via the parallel links 32 and 33 on the rear wheel side. be done. By the way, when the excitation of the solenoids b and c is stopped, the supply of pressure oil to the chamber g is cut off, the piston rod 26 is no longer moved, and the third check valve 1
9 will close, so stop there. On the other hand, solenoids b and c are energized and the piston rod 2
6 moves in the direction of arrow d and reaches the stroke end, the rear wheel is steered to the right by a predetermined angle and held. Therefore, when solenoids c and b are energized, the piston rod 26 moves in the direction of arrow d, and the rear wheels are steered to the right. Then, when the excitation of solenoids b and c is stopped, the piston rod 26 stops at that location, and the steering of the rear wheels is also maintained in the middle of steering.

On the other hand, a case where solenoids c and a are excited will be described. In this case, the first solenoid valve operates in the direction of arrow e from the neutral position in FIG. As a result, as described above, the tip of the lock piece 30 comes out of the annular groove 26c of the piston rod 26 of the rear wheel steering hydraulic cylinder 25, and the piston rod 26 becomes free. Further, a part of the pressure oil flowing through the oil passage 9 is sent to the third check valve 19, and the oil passages on the upstream side and the downstream side of the third check valve 19 communicate with each other. On the other hand, the second electromagnetic switching valve 16 operates from the neutral position in the direction of arrow e in FIG. The oil is sent to the chamber f of the rear wheel steering hydraulic cylinder 25 via the oil passage 7a → the first check valve 17 → the oil passage 7a. On the other hand, a part of the pressure oil flowing through the oil passage 7a on the upstream side of the check valve 17 is sent to the second check valve 18 via the oil passage 21, and the oil on the downstream side of the second check valve 18 is sent to the second check valve 18 via the oil passage 21. The passage 7b and the oil passage 7b on the upstream side communicate with each other, and the oil passage 7b,
7b communicates with the reservoir 3 via the R port of the second electromagnetic switching valve 16 and the low pressure oil passage 6'. Therefore,
While the oil in the chamber g is returned to the reservoir 3, the piston rod 26 of the rear wheel steering hydraulic cylinder 25 moves in the direction of the arrow e, and the parallel links 32 and 33 on the rear wheel side move.
The rear wheels are steered to the left via the By the way, when the excitation of the solenoids a and c is stopped, the supply of pressure oil to the chamber f is cut off, the piston rod 26 is no longer moved, and the third check valve 19 is closed, so it stops at that location. On the other hand, when the solenoids a and d are energized and the piston rod 26 moves in the direction of arrow e and reaches the stroke end, the rear wheel is steered to the left by a predetermined angle and held. Therefore, when solenoids c and a are energized, the piston rod 26 moves in the direction of arrow e, and the rear wheels are steered to the left. When the excitation of solenoids c and a is stopped, the piston rod 26 stops at that location, and the steering of the rear wheels is also maintained midway.

Next, a control circuit used in the control device 37 shown in FIG. 1 will be explained using FIG. 3. In FIG. 3A, 41 is a steering wheel steering sensor that detects the steering angle of the steering wheel. A voltage of 8V is applied to one end of the steering wheel steering sensor 41, and the other end is grounded. Contact point a of this steering wheel steering sensor 41 is when the steering wheel 38 is in the neutral position.
It is located in the middle of the sensor 41 so as to output a voltage of 4V, and moves up and down in accordance with the steering of the handle 38. For example, when the handle 38 is turned to the right, it moves in the direction of the arrow, and when the handle 38 is turned to the left, it moves in the opposite direction. In other words, handle 3
8 to the right, the output voltage of the steering wheel steering sensor 41 obtained from the contact point a increases. The output of the steering wheel steering sensor 41 is output from an integrating circuit consisting of a resistor R1 and a capacitor C1.
The signal is input to terminals "6" and "7" of the first window comparator 43 via the operational amplifier 42. This first window comparator 43 is also made by Siemens.
TCA965 is used, and its input/output characteristics are
It is shown in the figure. This first window comparator 43 is connected to the "lower" terminal (terminal 14), "upper" terminal (terminal 2), and "inner" terminal depending on which angle the steering angle of the handle 38 is within ±180°. Terminal (terminal 1
3) Signals A (SR), B (SL), and H output from
(SN) level changes. Here, signal A is a signal indicating that the steering wheel 38 is turned to the right;
Signal B is a signal indicating that the handle 38 is turned to the left, and signal H is a signal indicating that the handle 38 is turned within 180 degrees. And the first
The signal H outputted from the "inner" terminal of the window comparator 43 is inputted to the +Tr terminal of the first mono multivibrator 44. When the input of this first mono multivibrator 44 is switched to an H level signal, its Q output is maintained at an H level state for a certain period of time. The output of this first mono-multivibrator 44 is input to one input terminal of an AND circuit 45. A LOCK signal, which will be described later, is input to the other input terminal of the AND circuit 45. This LOCK signal becomes an H level signal when the lock piece 30 shown in FIG. 2 is inserted into the annular groove 26c. The output of this AND circuit 45 is output as an error signal ER. Furthermore, the signal H is input to the solenoid drive circuit 46.
This solenoid drive circuit 46 excites the solenoid coil c when an H level signal is input. That is, when the handle 38 is turned by more than ±180°, the signal H becomes H level, and the solenoid coil c shown in FIG.

Furthermore, the output of the operational amplifier 42 is input to a voltage switching circuit 47 to convert the voltage level.
The output signal V _s of this voltage conversion circuit 47 is input to one terminal of a comparator 48 . a steering angle of the steering wheel detected by the steering wheel steering angle sensor 41;
That is, the steering angle of the front wheels is converted via the operational amplifier 42 and the voltage conversion circuit 47 into a signal V _s indicating the target steering angle of the rear wheels corresponding to the steering angle of the front wheels. Hereinafter, this signal V _s will be referred to as a target rear wheel steering angle signal V _s based on the front wheel steering angle. Further, a signal V _f , which will be described later, is input to the + terminal of the comparator 48. This signal V _f is a signal proportional to the steering angle of the rear wheels. And this comparator 48
The output signal ΔV (V _f −V _s ) is input to the “6” and “7” terminals of the second window comparator 49.
This second window comparator 49 is manufactured by the same Siemens company as the first window comparator 43.
TCA965 is used, and its input/output characteristics are 4th
It is shown in the figure. The second window comparator 49 changes the levels of the output signals RR and RL according to the input signal. Here signal RR
is a signal that becomes H level when the rear wheels are steered to the right, and signal RL is a signal that becomes H level when the rear wheels are steered to the left. The signal RR is input to one input terminal of AND circuits 50 and 51, respectively. Further, the signal RL is supplied to the AND circuit 52,
53, respectively. The signal A is input to the other input terminals of the AND circuits 50 and 52, respectively. moreover,
Signal B is input to the other input terminals of the AND circuits 51 and 53, respectively. The output signals of the AND circuits 50 to 53 are referred to as signals D to F as shown in the figure. Here, signal D becomes H level when the front wheels are turned to the right (R) and the rear wheels are also steered to the right (R), and signal E is when the front wheels are turned to the left (L).
Signal F becomes H level when the front wheels are steered to the right (R) and signal F becomes H level when the front wheels are steered to the right (R) and the rear wheels are steered to the left (L). The H level is reached when the rear wheels are steered to the left (L) when turning left (L).

Furthermore, the output signal ΔV of the comparator 48
is "6" of the third window comparator 54,
It is input to the "7" terminal. This third window comparator 54 becomes H level when the output signal ΔV is, for example, 1.5 degrees or more. In other words, this third
The window comparator 54 is also made by Siemens.
TCA965 is used, and the output of its "inner" terminal is output as signal K.

Further, the output of the operational amplifier 42 is input to a steering direction detection circuit 56 via an operational amplifier 55. This steering direction detection circuit 56 detects the steering direction of the steering wheel 38, and when the steering wheel 38 is turned to the right, that is, the front wheels are turned to the right, its output signal DR goes to H level, and the steering wheel 38 is turned to the left. Then, its output signal DL becomes H level. In other words, the potential at the connection point b between the capacitor C2 and the resistor R2 is input to one terminal of the comparator 561 and the + terminal of the comparator 562, and
When 8 is turned to the right, the output of op amp 55 is 4V.
Since it is larger, capacitor C2 is charged with the polarity shown. Therefore, the potential at point b becomes greater than 4V. Therefore, the output of comparator 561 is at L level and the output of comparator 562 is at H level.
The output of NAND circuit 563 becomes H level, and the output of NAND circuit 564 becomes L level. Further, the signal DR is input to one input terminal of the AND circuit 57a, and the signal DL is input to one input terminal of the AND circuit 57a.
It is input to one input end of b. Here, the other input terminal of the AND circuit 57a is connected to the signal G.
However, the signal D is input to the other input terminal of the AND circuit 57b. Furthermore, the output of the AND circuit 57a is connected to one input terminal of the OR circuit 58a, and the output of the AND circuit 57b is connected to the OR circuit 58.
It is input to one input end of b. Here, the signal F is input to the other input terminal of the OR circuit 58a.
The signal E is input to the other input terminal of the OR circuit 58b. The output signal I (RL') of this OR circuit 58a is used as a signal to steer the rear wheel to the left (L), and the output signal J (RR') of the OR circuit 58b is used as a signal to steer the rear wheel to the right (R). Output.

Further, 59 is a rear wheel steering sensor that detects the steering angle of the rear wheels. One end of this rear wheel steering sensor 59 is
A potential of 8V is applied, and the other end is grounded. The contact c of this rear wheel steering sensor 59 is located in the middle of the sensor 59 so as to output a voltage of 4V when the rear wheels are not being steered, and moves up and down in accordance with the steering of the rear wheels. For example, if the rear wheel is steered to the left, the vehicle moves in the direction of the arrow, and if the rear wheel is steered to the right, the vehicle moves in the opposite direction. In other words, as the rear wheels are steered to the left, the output voltage obtained from contact point c increases. The output of the rear wheel steering sensor 59 is sent to the fourth window comparator 6 via an integrating circuit consisting of a resistor R3 and a capacitor C3, and an operational amplifier 60.
It is input to terminals "6" and "7" of 1. Further, the output of the operational amplifier 60 is input as a signal V _f to the + terminal of the comparator 48 . This fourth window comparator 61 is also made by Siemens.
TCA965 is used, and its input/output characteristics are 4th
It is shown in the figure. This fourth window comparator 61 outputs a signal FL which becomes H level when the rear wheel is steered to the left, and a signal FR which becomes H level when the rear wheel is steered to the right. This signal FL is input to one input terminal of the AND circuit 62b, and the above signal FL is input to one input terminal of the AND circuit 62b.
FR is input to one input terminal of the AND circuit 62a. HVEL signals, which will be described later, are input to the other input terminals of the AND circuits 62a and 62b, respectively. This HVEL signal indicates that the vehicle speed is, for example, 20km/h.
When it becomes higher than h, it becomes H level. Furthermore, the output of the AND circuit 62b is input to one input terminal of an OR circuit 63b, and the output of the AND circuit 62a is input to one input terminal of an OR circuit 63a.
The output of the OR circuit 63b is input to one input terminal of an AND circuit 64b, and the output of the OR circuit 63a is input to one input terminal of the AND circuit 64a. The signal J is input to the other input terminal of the AND circuit 64b, and the signal I is input to the other input terminal of the AND circuit 64a. Further, the output of the AND circuit 64b is input to one input terminal of an AND circuit 65b, and the output of the AND circuit 64a is input to one input terminal of the AND circuit 65a. Here, the signal H is input to the other input terminals of the AND circuits 65a and 65b, respectively. Furthermore, the output of the AND circuit 65a is input to a solenoid drive circuit 66a, and the output of the AND circuit 65b is input to a solenoid drive circuit 66b. The output of the solenoid drive circuit 66a is connected to the solenoid coil a shown in FIG. 2, and the output of the solenoid drive circuit 66b is connected to the solenoid coil b shown in FIG. Here, the output of the solenoid drive circuit 66b is input to the - terminal of a comparator 67 for detecting disconnection. A reference voltage is input to the + terminal of this comparator 67, and the output of the comparator 67 is outputted as a disconnection signal FAIL via an inverter 68. That is, when the solenoid coil b is disconnected, the disconnection signal FAIL becomes H level. In addition, the AND circuits 65a and 65b
The output of is outputted as a signal SOLAB via an OR circuit 69.

By the way, the signals HVEL and A/TPS described later
The signal K is input to an OR circuit 70, and the output of the OR circuit 70 is input via an inverter 71 to the other input terminals of the OR circuits 63a and 63b.

By the way, the switch S1 is the lock piece 3 in Figure 2.
This is a lock pin switch that closes when 0 is inserted into the annular groove 26c. This lock pin switch S1
The output signal is outputted to the OR circuit 70 via the inverter 72 and to the lamp drive circuit 74 via the inverter 73. This lamp drive circuit 74 includes a lamp 75 that lights up when the lock piece 30 is removed from the annular groove 26c.
is connected. Incidentally, the output of the inverter 72 is inputted to the other side of the AND circuit 45 as a LOCK signal.

Furthermore, the output of battery B (12V) is outputted as a system power source via relay switch S2, and control of this relay switch S2 is performed by controlling the current flowing through LY1 of the recoil. The control of this relay coil LY1 will be described later.

Next, in FIG. 3B, 76 is an A/R that closes to the terminals "R" and "L" when the automatic lever (not shown) is located at the "R" and "L" positions.
It is a T position switch. The terminals "R" and "L" are each connected to an OR circuit 77.
That is, this OR circuit 77 outputs an H level signal when the automatic check lever is placed in the "R" or "L" position. This OR circuit 7
The output of 7 is input to one input terminal of an OR circuit 78. Further, the output of the AND circuit 78 is inputted to one input terminal of an OR circuit 79. Further, the other input terminal of this OR circuit 79 is connected to the above-mentioned signal.
SOLAB is entered. This signal SOLAB goes high when solenoid coil a or b is energized.
This is the signal that becomes the level. Further, the output of the AND circuit 78 is outputted via the inverter 80 as the A/TPS signal described above. This A/
Output as TPS signal. This A/TPS signal is a signal that becomes L level when the rear wheels are in a steerable state. Further, the output of the OR circuit 79 is inputted to one input terminal of an AND circuit 81. Further, 112 is the pressure switch described in FIG. 2, and this pressure switch 112 is a switch that is closed when the high pressure oil passage 6 is at a low pressure. The operation signal of the pressure switch 112 is inputted to the other input terminal of the AND circuit 81 via the inverter 82. Therefore, when the pressure in the high pressure oil passage 6 is low, the pressure switch 112 is closed and the output of the inverter 82 becomes H level. Furthermore, the output of the AND circuit 81 is input to the +Tr terminal of the mono multivibrator 83. When this mono multivibrator 83 receives an H level signal, its Q output remains at H level for a certain period of time.
That is, the output returns to the H level after being at the L level for a certain period of time after the H level signal is input. The above output is input to one input terminal of the AND circuit 84, and the output of the above AND circuit 81 is input to the other input terminal. Furthermore, the output of this AND circuit 84 is input to an OR circuit 85. A FAIL signal, which is the output of the inverter 68 in FIG. 3A, and an ER signal, which is the output of the AND circuit 45, are input to the OR circuit 85. The output of the OR circuit 85 is inputted via an inverter 86 to one input terminal of a NAND circuit 87a. The output of the NAND circuit 87a is input to one input terminal of the NAND circuit 87b, and the output of this NAND circuit 87b is input to the other input terminal of the NAND circuit 87a.
Furthermore, since the other input terminal of the NAND circuit 87b is inputted with a signal PRST, which will be described later and is initially at the L level, the NAND circuit 87 is in the initial state.
The output of a is at L level, and the output of NAND circuit 87b is at H level. And the NAND circuit 87a
The output of is connected via a drive circuit 88 to a buzzer 89a, a lamp 89b for indicating an error, and a relay LY1 shown in FIG. 3A for cutting off the system power.

Furthermore, the output of the AND circuit 81 is inputted via a drive circuit 90 to a hydraulic pump relay 91 that operates the hydraulic pump 2 shown in FIG. Further, the output of the AND circuit 81 is connected to a hydraulic pump lamp 93 via a drive circuit 92. This hydraulic pump lamp 93 lights up when the hydraulic pump 2 is operated.

Further, 94 is a vehicle speed sensor, and this vehicle speed sensor 9
The output of No. 4 is input to a vehicle speed detection circuit 95 to detect the vehicle speed. This vehicle speed detection circuit 95 detects the vehicle speed and compares whether the vehicle speed is a low vehicle speed, that is, 10 km/h or less, or whether the vehicle speed is a high vehicle speed, that is, 20 km/h or more.
In this vehicle speed detection circuit 95, a signal LVEL which becomes H level when the vehicle speed becomes low is inputted to the other input terminal of the AND circuit 78. Furthermore, this vehicle speed detection circuit 95 outputs a signal HVEL which becomes H level when the vehicle speed becomes high.

Reference numeral 96 denotes an ignition switch, and when the ignition switch 96 is turned on, battery B is supplied to the power supply circuit 97.

The potential at the connection point between the resistor R3 and the capacitor C3 in FIG. 3A is input to the + terminal of the comparator 98 and the - terminal of the comparator 99 in FIG. 3C. In other words, the comparator 98 detects whether the voltage of the rear wheel steering sensor 59 has exceeded the reference voltage and detects a disconnection failure of the sensor 59.
A disconnection failure of the sensor is detected by detecting whether the voltage has fallen below the reference voltage. The outputs of the comparators 98 and 99 are respectively output from the OR circuit 1.
00 to the OR circuit 85 in FIG. 3B as a FAIL signal.

Next, the operation of this invention configured as described above will be explained. For example, the steering state of the rear wheels when the steering wheel 38 is turned to the right and the front wheels are steered to the right will be described. When the steering wheel 38 is turned to the right, the contact point a of the steering wheel steering angle sensor 41
moves in the direction of the arrow, so the voltage input to the first window comparator 43 increases. Then, when the handle 38 is turned to the right by more than 180 degrees, the signal H becomes H level. Therefore, the solenoid drive circuit 46 is driven and the solenoid c is energized. As a result, the lock piece 30 shown in FIG. 2 is removed from the annular groove 26, and the piston rod 26 becomes movable left and right. Further, the voltage of the output of the steering wheel steering angle sensor 41 is converted by a voltage conversion circuit 47, and is inputted to the - terminal of a comparator 48 as a target rear wheel steering angle signal _Vs based on the steering angle of the front wheels. On the other hand, a signal V _f proportional to the rear wheel steering angle output from the rear wheel steering sensor 59 is input to the + terminal of the comparator 48 . At this point, the rear wheels have not yet been steered, so as the steering wheel 38 is turned to the right, the signal V _s increases. Then, when the signal V _s becomes larger than the signal V _f and ΔV=V _f -V _s becomes a certain value or more, the output of the comparator 48 becomes L level. This results in
The signal RL output from the second window comparator 49 becomes H level. Here, handle 3
8 is turned to the right, the signal A output from the first window comparator 43 is at H level. Therefore, the signal F output from the AND circuit 52 becomes H level.

Further, since the output signal of the steering wheel steering angle sensor 41 is input to the steering direction detection circuit 56, its output signal DR is at H level and its output signal DL is at L level.

Further, the signal F is outputted as a signal I via an OR circuit 58a. This signal I is input to one input terminal of the AND circuit 64a. If an H level signal is input to the other input terminal of this AND circuit 64a, the output of the AND circuit 64a becomes H level. Here, the signal H output from the first window comparator 43 is H as described above.
Therefore, the output of the AND circuit 65a becomes H level. Therefore, the solenoid drive circuit 6
Solenoid coil a is excited by 6a. When this solenoid coil a is excited, the rear wheels are steered to the left as described above. Then, when the rear wheel is steered to the left, the contact point c of the rear wheel steering sensor 59 moves in the direction of the arrow, so that the generated voltage increases. As a result, the signal V _f input to the + terminal of the comparator 48 increases, and when ΔV=V _f −V _s becomes less than a certain value, the steering of the rear wheels is stopped. That is, when the steering wheel 38 is turned 180 degrees to the right as shown in FIG. 5, the rear wheels are steered 2.5 degrees to the left and then stopped. Here, when the output of the AND circuit 65a becomes H level, the signal
SOLAB becomes H level.

As mentioned above, when the signal H output from the first window comparator becomes H level and the solenoid c is energized and the lock piece 30 comes out of the annular groove 26, the lock pin switch S1 is opened. LOCK, which is the output of inverter 72
The signal becomes L level. Since this LOCK signal is inverted by the inverter 73, the lamp drive circuit 74 is driven and the lamp 75, which confirms that the lock piece 30 is removed, is turned on.
On the other hand, if the lock piece 30 does not come out of the annular groove 26 even after a certain period of time has elapsed since the start of energizing the solenoid c, the lock pin switch S1 remains closed and the LOCK signal is at H level. Therefore, the output of the AND circuit 45 becomes H level, and the signal ER becomes H level. When this signal ER goes high, the output of the OR circuit 85 in FIG. 3B goes high, and the output of the NAND circuit 87a goes high. As a result, the drive circuit 88 causes the buzzer 89 to
a sounds, a lamp 89b indicating an error lights up, and the relay coil LY1 is energized. When this relay coil LY1 is energized, the relay switch S2 shown in FIG. 3A is turned off, and the voltage of the battery B is no longer supplied to the system, and the steering of the rear wheels is stopped.

Note that when ΔV outputted from the comparator 48, that is, the difference between the target rear wheel steering angle based on the front wheel steering angle and the rear wheel steering angle, becomes 1.5 degrees or more, the third
The output signal K of the window comparator 54 becomes H level. In other words, this is a case where the steering angle of the front wheels suddenly increases due to sudden steering, and the steering of the rear wheels cannot follow the steering angle. In this case, the signal K is input as an L level signal to the other input terminal of the AND circuit 64a via the inverter 71 and the OR circuit 63a. Therefore, as mentioned above, the signal I becomes H.
Even if it is at L level, the output of the AND circuit 64a is set to L level, and the rear wheels are not steered.

By the way, when the handle 38 is turned 180 degrees to the right and quickly returned to the left, the signal RR output from the second window comparator 49 becomes H level and the signal D is output as an H level signal. This signal D is input to the AND circuit 57b, but since the output of the NAND circuit 564 is at L level, the signal J is not output. In other words, even if the steering wheel 38 is turned 180 degrees to the right and quickly returned to the left, the rear wheels will not be returned to the right and will remain steered 2.5 degrees to the left. In this way, overshoot of the rear wheel steering angle is allowed, and hunting of the rear wheels when the steering wheel 38 is quickly turned is prevented.

Hereinafter, when the steering wheel 38 is further turned to the right, the output voltage of the steering wheel steering angle sensor 41 increases, so a signal is input to the - terminal of the comparator 48.
When the value of V _s increases and ΔV = V _f - _{V s} exceeds a certain value, the signal RL output from the second window comparator 49 becomes H level again, and the signal F
becomes H level. Similarly, solenoid a
is excited and the rear wheels are steered to the left. Then, the output of the rear wheel steering angle sensor 41 increases, and the value of the signal V _f input to the + terminal of the comparator 48 increases, and ΔV = V _f - V _s becomes less than a certain value, and the rear wheel steering angle increases. will be stopped. In this way, when the steering wheel 38 is turned and the difference between the target rear wheel steering angle based on the front wheel steering angle and the rear wheel steering angle exceeds a certain level, the rear wheels are steered and the rear wheel steering angle changes to the front wheel steering angle. When the rear wheels are steered to an angle corresponding to , the steering of the rear wheels is stopped. Then, when the front wheels are further steered and the difference between the target rear wheel steering angle based on the front wheel steering angle and the rear wheel steering angle becomes a certain value or more, the rear wheels are steered. As a result, the steering angle of the rear wheels is controlled in steps as shown by the broken line A in FIG.

On the other hand, the operation when the handle 38 is turned to the right and returned to the left will be explained. In this case, by returning the handle 38 to the left, the signal V _s input to the - terminal of the comparator 48 will decrease, and when ΔV = V _f - V _s exceeds a certain value, the output of the comparator 48 will decrease. It becomes H level.
Therefore, the signal RR output from the second window comparator 49 becomes H level. Here, the handle 38 is turned to the right again, so the signal A
is H level. Therefore, the output signal D of the AND circuit 50 takes the H level, and the AND circuit 57b and
Signal J is set to H level via OR circuit 58b. Therefore, an H level signal is input to the solenoid drive circuit 66b via the AND circuits 64b and 65b. Therefore, the solenoid drive circuit 66b is energized and the rear wheels are steered to the right as described above.
Then, when the rear wheel is steered to the right, the contact point c of the rear wheel steering sensor 59 moves in the opposite direction to the arrow, so that the generated voltage decreases. As a result, the signal V _f input to the + terminal of the comparator 48 decreases, and when ΔV=V _f −V _s becomes less than a certain value, the steering of the rear wheels is stopped. Therefore, even when the steering wheel 38 is turned to the right and then returned to the left, the steering angle of the rear wheels is controlled in steps as shown by the broken line B in FIG.

Next, the steering state of the rear wheels when the steering wheel 38 is steered to the left from the neutral position will be described. When the steering wheel 38 is turned to the left, the contact point a of the steering wheel angle sensor 41 moves in the opposite direction to the arrow, so that the voltage input to the first window comparator 43 becomes smaller. Then, when the steering wheel 38 is turned to the left by more than 180 degrees, the signal H becomes H level. Therefore, the solenoid drive circuit 46 is driven and the solenoid c is energized. As a result,
The lock piece 30 in FIG. 2 is removed from the annular groove 26,
The piston rod 26 becomes movable left and right. Further, the voltage of the output of the steering wheel steering angle sensor 41 is converted by a voltage conversion circuit 47, and is inputted to the - terminal of a comparator 48 as a target rear wheel steering angle signal _Vs based on the steering angle of the front wheels.
On the other hand, a signal V _f proportional to the rear wheel steering angle output from the rear wheel steering sensor 59 is input to the + terminal of the comparator 48 . At this point, the rear wheels have not yet been steered, so as the steering wheel 38 is turned to the left, the signal V _s becomes smaller. and,
When the signal V _f becomes larger than the signal V _s , ΔV=V _f −V _s
When the value exceeds a certain value, the output of the comparator 48 becomes H level. As a result, the signal RR output from the second window comparator 49 becomes H level. Here, when the steering wheel 38 is turned to the left, the signal B output from the first window comparator 43 is at H level. Therefore, the signal E output from the AND circuit 52 becomes H level.

Furthermore, since the output of the steering wheel angle sensor 41 is input to the steering direction detection circuit 56, its output signal DR is at L level and its output signal DL is at H level.

Further, the signal E is outputted as a signal J via an OR circuit 58b. This signal J is input to one input terminal of the AND circuit 64b. If an H level signal is input to the other input terminal of this AND circuit 64b, the output of the AND circuit 64b becomes H level. Here, the signal H output from the first window comparator 43 is H as described above.
Therefore, the output of AND circuit 65b becomes H level. Therefore, the solenoid drive circuit 6
Solenoid coil b is excited by 6b. When this solenoid coil b is excited, the rear wheels are steered to the right as described above. Then, when the rear wheel is steered to the right, the contact point c of the rear wheel steering sensor 59 moves in the opposite direction to the arrow, so that the generated voltage decreases. As a result, the signal V _f input to the + terminal of the comparator 48 decreases, and when ΔV=V _f −V _s becomes less than a certain value, the steering of the rear wheels is stopped. In other words, the fifth
As shown in the figure, when the steering wheel 38 is turned 180 degrees to the left, the rear wheels are steered 2.5 degrees to the right.

Hereinafter, when the steering wheel 38 is further turned to the left, the output voltage of the steering wheel steering angle sensor 41 decreases, so a signal is input to the - terminal of the comparator 48.
The value of V _s decreases, and when ΔV = V _f - _{V s} reaches a certain level or more, the signal RR output from the second window comparator 49 becomes H level again, and the signal E becomes H level.
level. Thereafter, the solenoid coil b is energized in the same manner, and the rear wheels are steered to the right. Then, the output of the rear wheel steering angle sensor 41 decreases, and the value of the signal V _f input to the + terminal of the comparator 48 becomes smaller, and ΔV = V _f - V _s becomes less than a certain value, and the rear wheel steering becomes smaller. will be stopped. In this way, when the steering wheel 38 is turned and the difference between the target rear wheel steering angle based on the front wheel steering angle and the rear wheel steering angle exceeds a certain level, the rear wheels are steered, and the rear wheel steering angle is changed to the front wheel steering angle. When the rear wheels are steered to an angle corresponding to the angle, the steering of the rear wheels is stopped. Then, when the front wheels are further steered and the difference between the target rear wheel steering angle based on the front wheel steering angle and the rear wheel steering angle becomes a certain value or more, the rear wheels are steered. As a result, the steering angle of the rear wheels is controlled in steps as shown by the broken line A' in FIG.

On the other hand, the operation when the handle 38 is turned to the left and then gradually returned to the right will be explained.
In this case, by returning the handle 38 to the right, a signal is input to the - terminal of the comparator 48.
V _s increases, and when ΔV=V _f −V _s exceeds a certain value, the output of the comparator 48 becomes L level. Therefore, the signal RL output from the second window comparator 49 becomes H level. here,
Since the steering wheel 38 is still turned to the left, signal B is at H level. Therefore, the AND circuit 53
The output signal G of becomes H level, and the AND circuit 57
a, signal I is set to H level via OR circuit 58a. Therefore, an H level signal is input to the solenoid drive circuit 66a via the AND circuits 64a and 65a. Therefore, the solenoid drive circuit 66a
is excited and the rear wheels are steered to the left as described above. When the rear wheel is steered to the left, the contact point c of the rear wheel steering sensor 59 moves in the direction of the arrow.
The generated voltage increases. As a result, the signal V _f input to the + terminal of the comparator 48 increases, and when ΔV=V _f −V _s becomes less than a certain value, the steering of the rear wheels is stopped. Therefore, even when the steering wheel 38 is turned to the left and then returned to the right, the steering angle of the rear wheels is controlled in steps as shown by the broken line B' in FIG.

Next, in FIG. 3B, when the automatic lever 76 is placed in the "R" or "L" position, the output of the OR circuit 77 becomes H level. The output of this OR circuit 77 is input to one input terminal of an AND circuit 78, and the signal LVEL from the vehicle speed detection circuit 95 is input to the other input terminal of this AND circuit 78. Since this signal LVEL is at H level when the vehicle speed is 10 km/h or less, the logic of AND circuit 78 is established and its output becomes H level. The output of this AND circuit 78 is inputted to one input terminal of an AND circuit 81 via an OR circuit 79. Here, this AND circuit 81
A signal from the pressure switch 112 is inputted to the other input end of the inverter 82 via the inverter 82, but since the pressure switch 112 is closed when the pressure in the high pressure oil passage 6 is low, this input signal becomes H level. Therefore, the logic of the AND circuit 81 is established. In other words, when the automatic lever 76 is placed in the "R" position to reverse the vehicle into a garage, or when the automatic lever 76 is placed in the "L" position and the vehicle is started from parallel parking, the rear wheels are steered. It becomes necessary to make a large turn. When the automatic lever 76 is located in the "R" or "L" position and the high pressure oil passage 6 is at low pressure, the hydraulic pump 2 is operated as described below to drain the pressure oil in the high pressure oil passage 6. put under high pressure. In other words, when the logic of the AND circuit 81 is established, the drive circuits 90 and 91 are activated and the hydraulic pump relay 91 is activated.
is excited, and the hydraulic pump lamp 93 lights up, indicating that the hydraulic pump 2 is operating. When the hydraulic pump relay 91 is excited, the motor 1 operates the hydraulic pump 2 and the pressure oil in the high pressure oil passage 6 is made high pressure. By the way, the AND circuit 81
When the level is reached, the mono multivibrator 83 is set. The Q output of the mono multivibrator 83 returns to the H level after the output of the AND circuit 81 goes to the H level and remains at the L level for a certain period of time. In other words, when the hydraulic pump 2 is operated and the oil pressure in the high pressure oil path 6 increases, the inverter 82
The output becomes L level, the output of the AND circuit 81 also becomes L level, and the operation of the hydraulic pump 2 is stopped. Also, the car starts running and the signal LVEL is L.
Since the output of the AND circuit 78 becomes L level, the signal A/TPS becomes H level.
Since this signal A/TPS is input to AND circuits 64a and 64b via OR circuit 70, inverter 71, and OR circuits 63a and 63b, steering of the rear wheels is prohibited. However, if the oil pressure in the high pressure oil passage 6 does not increase even after a certain period of time has passed since the output of the AND circuit 81 reaches the H level, the output of the inverter 82 remains at the H level. Therefore, the logic of the AND circuit 84 is established after a certain period of time, and its output becomes H level. Therefore, the NAND circuit 87
An L level signal is input to a, and its output is H.
become the level. Therefore, the drive circuit 88 is driven, the buzzer 89a sounds, the lamp 89b is displayed, and the relay coil LY1 is excited. When this relay coil LY1 is excited, the relay switch S2 opens and the battery B is no longer supplied as system power. Therefore, steering of the rear wheels is discontinued.

By the way, solenoid coil B in Fig. 3A is ×
Assuming that the broken line is drawn at mark F, the output of the comparator 67 becomes L level and the signal FAIL becomes H level. When the signal FAIL goes high, the output of the OR circuit 85 in FIG. 3B goes high, and the output of the NAND circuit 87a goes high. As a result, the drive circuit 88 causes the buzzer 8 to
9a makes a sound, a lamp 89b indicating an error lights up, and relay coil LY1 is energized. When this relay coil LY1 is energized,
Relay switch S2 is turned off, voltage from battery B is no longer supplied to the system, and steering of the rear wheels is stopped.

Furthermore, if the rear wheel steering sensor 59 in FIG. 3A is disconnected at the cross mark G, the output of the comparator 99 in FIG. 3C becomes H level and the signal is
FAIL is output via the OR circuit 100. Furthermore, if the rear wheel steering sensor 59 is disconnected at the cross mark H, the output of the comparator 98 in FIG.
Output via 0. Therefore, the signal FAIL is H.
When the level is reached, the buzzer 89a sounds as described above, the lamp 89b lights up, and the voltage from the battery B is no longer supplied to the system, and the steering of the rear wheels is stopped.

In the above embodiment, disconnection is detected only for solenoid coil b, but a comparator and an inverter may be provided so that disconnection can be similarly detected for solenoid coils a and c.

Furthermore, if the resistance of the solenoid coil b is large, an AND circuit may be provided next to the inverter 68, and the output of the AND circuit 65b may be inverted and input to this AND circuit.

Furthermore, in the above embodiment, the rear wheels can be steered when the automatic lever of the automatic vehicle is in the "R" or "L" position, but when the automatic lever is in the "P" or "N" position, the rear wheels can be steered. Sometimes the rear wheels may be steerable. Furthermore, in manual cars, the shift lever is set to "1" (low) or "R".
The rear wheels may be able to be steered when the vehicle is in use.

As detailed above, according to this invention, when the output of the comparison means exceeds a predetermined value, the control valve that controls the operation of the hydraulic actuator for steering the rear wheels is driven until the output of the comparison means becomes equal to or less than the predetermined value. Therefore, even if the rear wheel steering operation overshoots, as long as the output of the comparison means is below a predetermined value, the rear wheel steering angle will not be further corrected, and hunting will be effectively prevented and the system will be stabilized. At the same time, since there is no need to use expensive valves or motors, the device can be made inexpensive. A rear steering control device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the rear wheel steering device for an automobile according to this invention, FIG. 2 is a hydraulic circuit diagram showing its neutral state, FIG. 3 is a diagram showing a control circuit, and FIG. Figures A to C are diagrams showing the input/output characteristics of the first to fourth window comparators, and Figure 5 is a diagram for explaining the steering state of the rear wheels. 41... Steering wheel steering sensor, 43... First window comparator, 46... Solenoid drive circuit, 47... Voltage conversion circuit, 48... Comparator, 49... Second window comparator, 5
9... Rear wheel steering sensor, 66a, 66b... Solenoid drive circuit.

Claims (1)

[Scope of utility model registration request] a hydraulic power source, a hydraulic actuator that steers a rear wheel, a position switching type control valve that is provided between the hydraulic power source and the hydraulic actuator and that switches and controls the supply and discharge state of pressure oil to the hydraulic actuator, and a front wheel. a front wheel steering angle detection means for detecting a steering angle of the rear wheels; a rear wheel steering angle detection means for detecting a steering angle of the rear wheels; and a target calculated based on the front wheel steering angle detected by the front wheel steering angle detection means. a comparison means for detecting the difference between the rear wheel steering angle and the rear wheel steering angle detected by the rear wheel steering angle detection means; and when the output of the comparison means exceeds the predetermined value, the output of the comparison means 1. A rear steering control device comprising: control means for outputting a switching drive signal to the control valve until the control valve becomes equal to or less than a predetermined value.