JPS6283248A - Rear-wheel steering gear for automobile - Google Patents

Abstract

PURPOSE:To make a car turning radius reducible at need, by selecting a hydraulic control valve according to a front-wheel steering angle to be detected by a front-wheel steering angle detecting device and thereby making a rear-wheel steering hydraulic cylinder so as to be operated. CONSTITUTION:A front-wheel steering angle is detected by a front-wheel steering angle sensor, and a front-wheel steering angle signal to be obtained at that time is fed to a control unit. And, in turn, this control unit feeds a control valve 24 with a rear-wheel steering signal if the front-wheel steering angle exceeds a neutral dead zone setting steering angle, operating both first and second solenoid selector valves 25 and 26. When the first solenoid selector valve 25 operates, a tip of a lock piece 40 is pulled out of an annular groove 36c so that a piston rod comes free. And, the second solenoid selector valve 26 also operates, whereby pressure oil in a hydraulic pump 12b is fed to a chamber (g) of a hydraulic cylinder 35. With this constitution, the piston rod 36 moves and steers rear wheels via a parallel link.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention automatically steers the rear wheels of an automobile according to the steering angle of the front wheels, making it possible to easily perform driving operations such as parking in a garage or making sharp turns. This invention relates to a rear wheel steering system for automobiles.

[Technical Background of the Invention and Problems Therewith] Generally, there is a limit to the minimum turning radius of an automobile, and as the vehicle body becomes larger, the radius increases proportionally. For this reason, general passenger cars, especially large passenger cars, etc., are unable to turn in a tight corner, making it extremely difficult to drive when turning or parking on a narrow road.

[Object of the invention] This invention was made in view of the above problems.
It is an object of the present invention to provide a rear wheel steering device for an automobile that can reduce the turning radius as necessary even in a vehicle such as a large passenger car.

[Summary of the Invention] That is, a rear wheel steering device for an automobile according to the present invention includes a rear wheel steering hydraulic cylinder and a poppet valve that controls the operating direction of the rear wheel steering hydraulic cylinder by switching the direction in which the hydraulic pressure is supplied. a front wheel steering angle detection sensor that detects the steering angle of the front wheels; and a front wheel steering angle detection sensor that controls the hydraulic pressure control valve according to the front wheel steering angle detected by the front wheel steering angle detection sensor. The present invention further includes a rear wheel steering control device that performs a supply switching operation and operates the rear wheel steering hydraulic cylinder.

[Embodiments of the invention] A major embodiment of the present invention will be described below with reference to the drawings.

Figures 1 to 4 show its configuration. In these figures, 11 is an engine, and 12a and 12b are engine 1.
A hydraulic pump driven by 1, 13 a reservoir, 14
is the hydraulic pump 12a.

12b, an oil passage extending from one hydraulic pump 12a to the front wheel steering gear box 15 side, 16 a high pressure oil passage extending from the other hydraulic pump 12b, and 22 this high pressure oil passage 1.
The check valve 16a provided in the check valve 6 is an oil passage connecting the high pressure oil passage 16 on the upstream side of the check valve 22 and the reservoir 13, 2.
1 is a relief valve provided in this oil passage 16a, 23 is an accumulator provided in the high pressure oil passage 16 on the downstream side of the check valve 22, and the pressure on the downstream side of the check valve 22 including this accumulator 23 is If it is higher than the pressure, the hydraulic pump 1
The oil pressure from 2b is indicated by the arrow a-+b-+c→ in Fig. 3.
It is designed to circulate as shown in . Further, 24 is a control valve of the hydraulic circuit, and this control valve 24 is composed of first and second electromagnetic switching valves 25 and 26, and first and second check valves 27 and 28, and is configured to control the high pressure. An oil passage 16 is connected to the P boats of the first and second electromagnetic switching valves 25,26. Further, 20 is a low pressure oil passage extending to the reservoir 13, and this low pressure oil passage 20 is connected to the R boats of the first and second electromagnetic switching valves 25 and 26. Also,
Reference numerals 17a and 17b are oil passages on the second electromagnetic switching valve 26 side, and the first and second check valves 27 and 28 are interposed in these oil passages 17a and 17b. Further, 18 and 19 are oil passages on the side of the first electromagnetic switching valve 25, and 34 is a rear wheel steering hydraulic cylinder, and this rear wheel steering hydraulic cylinder 3
4 is composed of a cylinder 35 and a piston rod 36, and end plates 35a, 35 are provided at both ends of the cylinder 35.
d, and on the left side of the middle there is an annular partition wall 35b that partitions the inside of this cylinder 35 into a left part and a right part,
On the right side of the middle, there is an annular protrusion 35C that protrudes into the cylinder 35. Further, on the left side of the piston rod 36, which passes through the cylinder 35 and has both ends protruding outside the cylinder 35, a piston 36a partitions the inside of the cylinder 35 on the left side of the annular partition wall 35b into chambers f and Q. There is a large diameter portion 36b on the right side of the piston rod 36, and an annular groove 36 in this large diameter portion 36b.
G is provided.

Further, 37 is a sliding ring fitted into the piston rod 36 between the partition wall 35b and the large diameter portion 36b so as to be movable in the axial direction, and 38 is the sliding ring between the large diameter portion 36b and the end plate 35.
A sliding ring 39 is fitted into the piston rod 36 between the piston rod 36 and the cylinder 35 so as to be movable in the axial direction; The lock piece 40 is freely inserted and inserted, and the tip of the lock piece 40 can penetrate the wall surface of the cylinder 35 and move in and out of the cylinder 35. Further, 41 is a spring interposed between the lock piece 40 and the bottoms of the three cylinder bodies.
1 constantly urges the lock piece 40 in the direction of the piston rod 36. Further, the oil passage 17a on the downstream side of the first check valve 27 is connected to the cylinder 35, while the oil passage 17b on the downstream side of the second check valve 28 is connected to the cylinder 35.
5, and an oil passage 16 branched from the high pressure oil passage 16.
' is the chamber of the cylinder 35, and the oil passage 19 on the downstream side of the first electromagnetic switching valve 25 is connected to the sliding ring 3.
7.38 is connected within the cylinder 35. 31 is from the oil passage 17a on the upstream side of the first check valve 27 to the second check valve 27.
An oil passage 32 extends behind the check valve 28 from the oil passage 17b on the upstream side of the second check valve 28 to the first check valve 2.
This is an oil road that extends behind 7.

Next, FIG. 4 shows a specific example of the hydraulic control valve 24, and as is clear from the figure, the first electromagnetic switching valve 25, the first and second check valves 27, 28, and Two electromagnetic switching valves 26 (26A, 26B) are installed approximately in that order from bottom to top. Further, each electromagnetic switching valve 25.26A of this hydraulic control valve 24.

26B is constructed using a poppet valve rather than a typical spool valve. Note that 24a to 24C are the casings of this control valve 24, and 24d to 24f are its end plates. Further, 29.30 is the first and second check valve 27.
, 28, respectively.
In the lot, these parts 27.29 and 28.30 are respectively arranged on the same axis, and a spring 27a is arranged between the first check valve 27 and the end plate 24d, and the spring 27a is connected to the second check valve 27. 28
A spring 28a is interposed between the end plate 24e and the end plate 24e, and is normally in the state shown in this figure. Further, the pilot oil passage 31 in FIGS. 2 and 3 is realized by the movement of the piston rod 30 in FIG. 4, and the pilot oil passage 32 is realized by the movement of the piston rod 29 in FIG. In addition, in FIGS. 2 to 4, reference numeral 33 indicates first and second check valves 27 and 28 that contact the first and second check valves 27 and 28 from the oil passage 18 on the downstream side of the first electromagnetic switching valve 25. Further, 25a is a spring of the first electromagnetic switching valve 25, and 26a and 26b are a spring of the second electromagnetic switching valve 26 (26A).

26B) and 42.4 in Fig. 1 above.
3 is a piston rod 36 of a hydraulic cylinder 34 for rear wheel steering.
44. 45 is a suspension on the rear wheel side, 46 is a front wheel steering angle sensor, 47 is a rear wheel steering control device, and 48 is a rear wheel steering angle sensor. The front wheel steering angle sensor 46 and the rear wheel steering angle sensor 48 detect the steering angles of the front wheels and rear wheels in real time, and supply the front wheel and rear wheel steering signals obtained at that time to the control device 47. The control 'a' device 47 transmits a rear wheel steering signal to the control valve 24 (the first When the front wheels are steered in the direction of the neutral position and the front wheel steering angle becomes smaller than the set steering angle, the signal for returning to the neutral position is sent to It is supplied to the control valve 24 (first and second electromagnetic switching valves 25 and 26).

Next, the operation of the rear wheel steering position configured as described above will be explained.

When the automobile is running, the front wheel steering angle is detected by the front wheel steering angle sensor 46, and the front wheel steering angle signal obtained at that time is supplied to the control device 47.

Furthermore, when the front wheels are steered from the neutral position and the steering angle exceeds the neutral dead zone setting steering angle in FIG. 5 and exceeds the allowable range shown by hatching,
A rear wheel steering signal is supplied to the control valve 24, and the first. Activate the second electromagnetic switching valve 25,26. At this time, if the first electromagnetic switching valve 25 operates in the direction of arrow d in FIGS. 3 and 4 from the neutral position in FIG. → P boat of the first electromagnetic switching valve 25 → D port → It is supplied into the cylinder 35 between the reservoir rings 37 and 38 through the oil passage 19, and the lock piece 40 retreats against the spring 41. 40 comes out from the annular groove 36c of the piston rod 36 of the rear wheel steering hydraulic cylinder 35, and the rotating rings 37 and 38 move into the piston large diameter portion 3.
The pressing force against the piston 6b is released, and the piston rond 36 becomes free. Further, the second electromagnetic switching valve 26 also operates from the neutral position in FIG. 2 in the direction of arrow d in FIGS. It is supplied to vQ of the rear wheel steering hydraulic cylinder 35 through the P boat of the N magnetic switching valve 26 (26A) → the oil passage 17b → the second check valve 28 → the oil passage 17b. The stop valve 28 is pushed to the left in the figure by hydraulic pressure against the spring 28a.In this case, the movement of the stop valve 26a in the direction of the arrow d is transmitted to the piston rod 29, so that the first check valve 27 is pushed to the right against the spring 27a in FIG. The R boat of the valve 26b communicates with the reservoir 13 via the low pressure oil passage 20. Therefore, the chamber f of the cylinder 35
While the pressure oil inside is returned to the reservoir 13, the piston rod 36 of the rear wheel steering hydraulic cylinder 35 moves in the direction of arrow e, and the rear wheels are steered via the parallel links 42, 43 on the rear wheel side. As a result of the movement of the rear wheels, when the relationship between the front wheel angle and the rear wheel angle enters the hatching zone shown in FIG. The oil in f1g is stopped by check valves 27 and 28 to maintain the rear wheels at a predetermined steering angle.

The rear wheel steering control device 47 also supplies a rear wheel steering signal to the control valve 24 when the front wheels are steered from a certain steering angle position toward a neutral position and the steering angle becomes inside the set steering angle. First. Second electromagnetic switching valve 25.26 (
26A, 26B), and the first. Return the second electromagnetic switching valve 25°26 to the neutral position in FIG. At this time, the inside of the cylinder 39 and the inside of the cylinder 35 between the sliding rings 37 and 38 are connected to the reservoir 13 via the oil passage 19 → first 'R magnetic switching valve 25D boat → R boat → low pressure oil passage 20. The lock piece 40 is pushed into the cylinder 35 by the spring 41 and the pressure oil in the cylinder body 39 is returned to the reservoir 13 while the lock piece 40 projects into the cylinder 35 . At this time, since the piston rod 36 is operating in the direction of the arrow e as described above, the tip of the lock piece 40 comes into contact with the large diameter portion 36b of the piston rod 36. Also, at this time, the pressure oil of the hydraulic pump 12b passes through the high-pressure oil passage 16 → the P boat of the first electromagnetic switching valve 25 → the C boat → the oil passage 33, and the first. second piston 2
9.30, the first piston 29 and the first check valve 27 move to the right in FIG. Valve 27 → Oil line 1
7a → R boat of second electromagnetic switching valve 26b → Low pressure oil line 2
0, communicates with the reservoir 13 through the chamber f heli reservoir 13
While the oil is being supplied, the second piston 30 and the second check valve 28 move to the left in FIG. 28 → oil passage 17b → R boat of the second electromagnetic switching valve 26a → communicates with the reservoir 13 via the low pressure oil passage 20, and while empty Q pressure oil is returned to the reservoir 13, the piston rod 36 moves to the right (arrow) start moving in the opposite direction of e). Also, at this time,
Pressure oil flowing through the oil passage 16' reaches the cylinder 35.

i and the sliding ring 37 inside the cylinder 35.
．． Pressure oil between 38 and D boat of first electromagnetic switching valve 25 →
It is returned to the reservoir 13 via the R boat, and the sliding ring 3
7 is pressed to the right, and the sliding ring 38 moves to the left. In this case, since the large diameter portion 36b of the piston rod 36 is still on the left side with respect to the annular protrusion 35C, one sliding ring 38 comes into contact with the annular protrusion 35c and stops.

In this state, the piston 36 of the piston rod 36
a has returned to a neutral position between the end plate 35a and the annular partition 135b, and stops there.

On the other hand, while the piston rod 36 returns to the above direction, the lock piece 40 that was in contact with the large diameter portion 36b of the piston rod 36 causes the piston rod 36 (large diameter portion 36b) to return to the neutral position as described above. Then, the piston rod 36 is further pushed and protruded by the spring 41, and is engaged with the annular groove 36c of the large diameter portion 36b, thereby locking the piston rod 36. In this state, the rear wheels have also returned to the neutral position.

Note that the above effect applies when the front wheels are steered in one direction (either left or right) and the rear wheels are steered in one direction (either left or right), but when the front wheels are steered in the other direction. In this case, the first electromagnetic switching valve 25 of the safety valve 24 operates in the direction of the arrow d, and the second electromagnetic valve 26 operates in the direction opposite to the arrow d from the neutral position in FIG. The piston rod 36 of the hydraulic cylinder 35 moves to the right (in the direction opposite to the arrow e in FIG. 3) from the neutral position in FIG. 2 to steer the rear wheels in the other direction. FIG. 5 is an explanatory diagram summarizing the above-mentioned effects, and when the front wheel steering angle slowly increases or decreases, a step-like movement of the rear wheel within the hatch occurs.

Therefore, according to the rear wheel steering device configured as described above, since the rear wheels are automatically steered together with the front wheels, the turning radius of the automobile can be reduced. Also,
The hydraulic circuit in this steering system uses a hydraulic control valve 24 constructed using a poppet valve, so it is extremely responsive, small, and lightweight compared to the case where a general spool type control valve is used. It is a sake. Therefore, it is possible to realize an inexpensive and highly reliable rear wheel steering device in which the rear wheels that are steered in accordance with the steering angle of the front wheels have very good followability.

[Effects of the Invention] As described above, according to the present invention, a rear wheel steering hydraulic cylinder and a poppet valve that controls the operating direction of the rear wheel steering hydraulic cylinder by switching the direction in which the hydraulic pressure is supplied are used. a front wheel steering angle detection sensor that detects the steering angle of the front wheels; and a hydraulic pressure supply switching operation to the hydraulic control valve according to the front wheel steering angle detected by the front wheel steering angle detection sensor. Since the rear wheels are automatically steered, the turning radius can be reduced as necessary, even in vehicles such as large passenger cars. Furthermore, by configuring the hydraulic control valve using a poppet valve, a highly responsive rear wheel steering operation can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a rear wheel steering system of an automobile according to an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram showing the neutral state of the rear wheel steering in the 4N position, and FIG. 3 is a similar diagram. Fig. 4 is a hydraulic circuit diagram showing the state during steering; Fig. 4 is a sectional configuration diagram showing a specific example of a hydraulic control valve configured using a poppet valve;
The figure is a diagram showing the turning characteristics of the rear wheel steering device. 24... Hydraulic control valve, 35... Hydraulic cylinder for rear wheel steering, 46... Front wheel steering angle sensor, 47... Rear wheel steering control device, 48... Rear wheel steering angle sensor. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (1)

[Claims] A hydraulic cylinder for steering the rear wheels, a hydraulic control valve configured using a poppet valve that controls the operating direction of the hydraulic cylinder for steering the rear wheels by switching the supply direction of hydraulic pressure, and a front wheel that detects the steering angle of the front wheels. a steering angle detection sensor; and rear wheel steering control for causing the hydraulic pressure control valve to perform a hydraulic pressure supply switching operation to operate the rear wheel steering hydraulic cylinder in accordance with the front wheel steering angle detected by the front wheel steering angle detection sensor. What is claimed is: 1. A rear wheel steering device for an automobile, comprising: