JPH02124371A - Steering device of vehicle - Google Patents

Abstract

PURPOSE:To provide active controllability for front and rear wheels while the front/rear controlled balance is maintained good by furnishing a same-phase steering means to steer the rear wheels in the same direction as the front, an opposite-phase steering means to be actuated when the steering is started, and a phase advance steering means for cut-increasing the steering angle of the front wheels. CONSTITUTION:A power steering 6 is formed in combination of a steering gear assembly 9 with a power cylinder device 10 and an oil pump 13, which supplies oil pressure to a rotary valve 7. Therein a steering wheel 17 is coupled with the input shaft 7a of the rotary valve 7 and a torsion bar 8 through a phase advance steering means 14 and a column shaft 16. A two-gang rear power cylinder 90 is installed in such an arrangement as to couple a left and a right pivoting shaft 89, 89 of the rear-wheel suspension, and the left and right chambers 97a, 97b of this rear power cylinder are connected to a control valve 98 for the same phase, and the two cylinder chambers 92a, 92b are connected with another control valve 100 for opposite phase, which shall be controlled interlocked with the phase advance steering means 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to a vehicle steering system that controls the steering angles of front wheels and rear wheels.

(Prior Art) In four-wheel steering, it is known that dynamic characteristics during turns can be improved by actively controlling the steering angles of the front and rear wheels.

That is, at the start of steering, the rear wheels are momentarily reversed in phase and the steering angle of the front wheels is increased to balance the yaw rate and lateral acceleration. This improves the start-up of the rotational motion of the vehicle. Then, at the next moment, the vehicle returns to steady four-wheel in-phase steering and, for example, completes turn-in along the desired trajectory with the sideslip angle at zero.

In order to realize the operation of the four-wheel active steering concept, the steering system disclosed in Japanese Patent Application Laid-open No. 57-87759 is used, and the steering system disclosed in Japanese Patent Application Laid-Open No. 59-1867 is
It is conceivable to adopt the phase inversion control disclosed in Japanese Patent Publication No. 73 or Japanese Patent Laid-Open No. 191272/1983.

That is, JP-A-57-87759 discloses a system in which means for steering the front wheels and means for steering the rear wheels are independently controlled, and JP-A-57-87759 discloses a system in which means for steering the front wheels and means for steering the rear wheels are independently controlled.
No. 86773 or Japanese Unexamined Patent Publication No. 191272/1986 discloses a system in which the phase of the rear wheels is reversed by a single rear wheel operating means.

(Problems to be Solved by the Invention) However, since such four-wheel steering devices independently control the front wheels and rear wheels, the control balance between the front and rear wheels is likely to be lost. For this reason, sophisticated control is required to maintain a control balance between the front and rear wheels, which poses the problem of being quite expensive. Moreover, since the output of a single rear wheel operating means is controlled in addition to the above, and the phase of the rear wheels is reversed, the control becomes complicated.

This invention was made with attention to these circumstances,
The purpose is to provide a steering system for a vehicle that can perform simple control and actively control the front and rear wheels without losing the control balance between the front and rear wheels.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the steering device of the present invention includes an in-phase steering means that steers the rear wheels in the same direction as the front wheels, and a steering system in parallel with the in-phase steering means. a reverse phase steering means which is provided at the front wheel and which steers the rear wheels in a direction opposite to that of the front wheels at the start of a steering operation; a phase advance steering means which increases the steering angle of the front wheels; the phase advance steering means and the reverse phase steering means; control means for commonly controlling the operation of the

(Function) According to the steering device of the present invention, the rear wheel steering angle is obtained from the combined output of the parallel in-phase steering means and the anti-phase steering means, and the common control means allows the front wheels to advance in phase and the rear wheels to move in reverse phase. is being controlled. Therefore, the control balance between the front and rear wheels is not disrupted, and the control of the phase reversal of the rear wheels can be simplified.

(Example) The present invention will be described below based on a first example shown in FIGS. 1 to 14. FIG. 1 shows a four-wheel steering system for a vehicle, where 1a and 1b are left and right front wheels. Front wheel 1
a and lb are rotatably supported by knuckles 2a and 2b that are supported so as to be swingable in the horizontal direction with respect to a vehicle body (not shown). Further, the knuckles 2a and 2b are tie rods 3a.

3b, it is connected to a vehicle speed sensitive power steering 6, which is made up of a combination of a rack 4 and a pinion 5, for example. That is, the power steering 6 is connected to the rack 4
．． Pinion 5. A steering gear assembly 9 includes a rotary valve 7 and a torsion bar 8, a steering power cylinder device 10 (having a piston 12 connected to a rack 4 in a power cylinder 11) connected to a rotary valve 7, and a rotary valve 7
It is combined with an engine-driven oil pump 13 (for power steering) that supplies hydraulic pressure to the engine.

- Piston rods 12a and 12b on both sides of the piston 12 of the power cylinder device 10 are connected to the tie rods 3a and 3b.

It also serves as an input part for the steering gear assembly 9.
The valve input shaft 7a of the rotary valve 7 connected to the pinion 5 and the torsion bar 8 include a phase advancement mechanism 14 (phase advancement steering means), an intermediate joint 15, which will be described later.
．． Steering wheel 1 via column shaft 16
7 are connected. Thereby, when the steering wheel 17 is operated, the rack 4 is driven in the same direction as the steering wheel 17. At the same time, the hydraulic pressure generated by the oil pump 13 is supplied through the rotary valve 7 to a left chamber 18 and a right chamber 19 formed on both sides of the piston 12, so that the steering force of the steering wheel 17 can be assisted. Note that the oil pump 13 is a pump having a characteristic that the discharge flow rate decreases as the rotational speed of the engine 20 increases from a certain range.

Here, to explain the phase advance mechanism 14, the phase advance mechanism 14 includes two sets of planetary gear mechanisms 21.
22 and a control valve 23.

Specifically, 37 is a case installed at the upper end of the case 9a of the steering gear assembly 9, and 37a is a screw-type cap that closes the upper opening of the case 37. The case 37 and the cap 37a are fitted with a bolt 35 passing through them and a nut 3 screwed into the bolt end.
6 is fixed to the case 9a, and constitutes the body of the phase advancing mechanism 14. An input shaft 24 is rotatably provided on the upper side of the case 37 coaxially with the valve input shaft 7a. Note that 24a is a bearing that rotatably supports the input shaft 24. A sun gear 25 is integrally provided on the lower outer periphery of the input shaft 24. A ring gear 26 supported by the case 37 is provided around the sun gear 25. And this ring gear 26
and the sun gear 25, four sets of planetary gears 27 that mesh with both gears are provided, and the −th stage planetary gear mechanism 2
1. The above-mentioned intermediate joint 1 is attached to the upper part of the input shaft 24 protruding from the cap 37a.
5 are connected.

Also, the end of the valve input shaft 24 is connected to the case 9a.
It protrudes upward from the upper end opening. On the outer periphery of the end of the valve input shaft 24 that enters the case 37, a sun gear 2 having the same specifications as the -stage planetary gear 21 is provided.
8 are integrally provided. Further, a ring gear 29 having the same specifications as the negative stage is provided in the case 37 surrounding the sun gear 28. And this ring gear 29
Four sets of rotatable planetary gears 31 coaxially connected to the first-stage planetary gear 27 via a shaft 30 are provided between the second-stage planetary gear mechanism 22 and the sun gear 28 .

Note that the planetary gear 27 and the planetary gear 31 are connected to a holder 32 that holds the shaft 30. The valve input shaft 24 is supported so as to be movable in the circumferential direction around the axis of the valve input shaft 24 by a gear regulating holder 33 provided at the end of the shaft.

The cap 37a is provided with an adjuster 38 that restricts the vertical movement of the bearing 24a, and the planetary gear mechanism 21, 22 is assembled to the steering gear assembly 9 in a predetermined position. In addition, 39 is a sealing member, 40 is a nut for preventing loosening of the adjuster 38, and 41 is a ring gear 26.
This is a spacer for regulating the movement of 29 in the vertical direction.

Further, the tip of the valve input shaft 7a is inserted into a four part 43 provided at the axial end of the input shaft 24. The end of the torsion bar 8 is connected to the insertion end of the valve input shaft 7a with a pin 44, and when the steering wheel 17 is operated with the ring gear 26° 29 fixed, the steering angle of the steering wheel 17 is changed. First stage and second stage planetary gear mechanism 2
1°22, so that the same ratio can be transmitted to the rotary valve 7 and the torsion bar 8. However, a metal bushing 45 is provided between the insertion end of the valve input shaft 7a and the four parts 43 to prevent rattling in the circumferential direction.
is an intermediary.

Note that a safety device 46 is provided in the −-stage planetary gear mechanism 21 to prevent more than necessary torque from being applied to the steering wheel 17. Specifically, safety device 4
6 provides four parts 47 on the outer peripheral surface of the ring gear 26. Also, on the case 37 side, there is a bottle part 48 that fits into the recess 47 and the recess. A set screw composed of a spring 49 and an adapter part 50 is provided to bias the bottle part 48 in the fitting direction. With this structure, the movement of the ring gear 26 in the rotational direction is restricted by the concave-convex fitting, and when an excessive steering force exceeding the preload from the steering wheel 17 enters the ring gear 29, the concave-convex fitting is released and the ring gear 26 is released. The gear 26 is rotatable and the planetary gear mechanism 21
．． 22 from excessive torque. In addition,
Although not shown in the drawings, a stopper portion configured by fitting stepped portions is provided at the input shaft end and the valve input shaft end that are in the fitted state, and when the ring gear 26 rotates a certain amount, a stopper portion is provided. , the two contact each other and the steering force from the steering wheel 17 is transferred to the input shaft 2.
4 to the valve input shaft 16.

A case 37 in which such a planetary gear mechanism 21, 22 is assembled
The above-mentioned control valve 23 is assembled to.

That is, to explain the control valve 23, 51 is an elongated valve body that is integrally provided in a case portion adjacent to the ring gear 29 along a direction perpendicular to the center of the planetary gear mechanism 22.

A substantially cylindrical valve chamber 52 is formed within the valve body 51 along a direction perpendicular to the axis of the ring gear 29 . A spool 53 is disposed within the valve chamber 52. The spool 53 has one end attached to a plug 54 attached to the end of the valve chamber 52.
The other end is slidably supported by a plug 56 attached to the other end of the valve chamber 52 via an adapter 55. Each shaft end surface of the spool 53 faces the holes 54a, 56a of the plug 54, 56. Further, inside the adapter 55, a spring chamber 55 is provided.
a is formed. In this spring chamber 55a,
A spring 5 is hooked between a washer 56a slidably fitted into a small diameter portion 53a on the outer periphery of the end of the spool 53 and a snap ring 57 fixed to the end of the small diameter portion 53a.
8 is accommodated, and the spool 53 is positioned by a spring 58. Note that 59 is a nut that prevents the plugs 54 and 56 and the adapter 56 from loosening.

Further, a plate-shaped lever 60 is provided on the outer periphery of the spool 53, movably penetrating the shaft portion of the spool 53. The lever 60 is arranged on a line that intersects the axis of the ring gear 29 at right angles.

Then, the circular arc portion formed at the end of the lever 60 on the ring gear 29 side passes through the through hole 61 formed in the valve body portion and the case portion, and is engaged with the groove portion 62 formed in the outer peripheral surface of the ring gear 29. ing.

Further, the arc portion formed at the remaining narrow end of the lever 60 is rotatable in a groove 65 of a plate 64 provided on the inner bottom surface of an adapter 63 attached to the valve chamber 52 so as to cover the end. This allows the entire lever to rotate along the axis of the spool 53 using the end on the plate 64 side as a fulcrum. Note that 66 is a locking nut of the adapter 63, and 67 is a wave-shaped washer interposed between the plate 64 and the inner bottom surface of the adapter 63.

A collar 68 is slidably fitted onto the outer periphery of the spool portion on the plug 54 side with the lever 60 in between, and a sleeve 69 is slidably fitted onto the outer periphery of the spool portion on the plug 56 side. The collar 68 and sleeve 69 are
their outer ends and plugs 54. The elastic force of the springs 70a and 70b provided between the adapter 55 (Brillo
) are pressed against both sides of the lever 60 to position the three parts including the lever 60 on the spool 53. On the outer peripheral surface of the spool 53 covered with the sleeve 69, two inlet-side chambers 71 and 72 formed of annular grooves are arranged in parallel. On the other hand, on the inner circumferential surface of the sleeve 69, three outflow side chambers 73 to 75 formed of grooves are provided at the boundary between the chambers 71 and 72. The chamber 71 is connected to the collar 68 via a passage 76 provided inside the spool 53.
It communicates with a pressure receiving chamber 77 which also serves as a spring chamber and is formed between the plug 54 and the plug 54 . Further, the chamber 72 communicates with a pressure receiving chamber 79 which also serves as a spring chamber and is formed between the sleeve 69 and the adapter 55 via a passage 78 similarly provided inside the spool 53. The central chamber 74 on the outflow side is connected to the discharge section of the oil pump 13 via a boat 80 provided on the valve body 51. The remaining room 73
．． 75 is connected to the inlet boat (not shown) of the rotary pulp 7 of the steering gear assembly 9 via a boat 81 provided on the valve body 51, and is connected to the oil pump 13.
This constitutes a follow-up type servo valve (spool valve) that can hold the ring gear 29 at a predetermined position or increase the input steering angle using the hydraulic pressure generated by the servo valve. That is, the passage 7 is in the pressure receiving chamber 77.79.
Since the structure is such that oil from the oil pump 13 flows in through 6.78, when the sleeve 69 is displaced by the steering reaction force of the second stage ring gear 29, the chambers 71, 72 and 73-7
5, a large amount of oil flows into the displaced one pressure receiving chamber side, and at the same time, a large amount of oil flows out from the remaining pressure receiving chamber side, and in order to return the ring gear 29 to its original state, the displaced sleeve 69 is I am trying to return it to its original position. Further, when a force is applied from the plugs 54 and 56 to displace the spool 53, the sleeve 69 moves to follow the displacement of the spool 53, rotates the lever 60, and rotates the ring gear 29 toward the additional cutting side. becoming/being (
(variable steering gear ratio).

On the other hand, 82a and 82b are left and right rear wheels. Rear wheel 82a
, 82b are supported by a double wishbone type rear wheel suspension with a toe control mechanism. That is, the rear wheel suspension is attached to the cross member 83.
A pair of upper and lower lateral arms consisting of an upper arm 84 and a lower arm 85 are provided, and an arm formed by connecting a toe control arm 86 and a trailing arm 87 at an intermediate joint 88 is connected. A rear wheel 82a is attached to the end of the arm via a wheel support (not shown).
, 82b. intermediate joint 88
is a pivot shaft 8 such as a pin whose axis of rotation is set in a substantially vertical direction.
9, and according to the displacement of the intermediate joint point, the rear wheel 82a.

82b can be steered.

A double rear power cylinder 9o is provided on the cross member 83 so as to connect the left and right pivot shafts 89, 89 of the rear wheel suspension. That is, the rear power cylinder 9o has a cylinder 94 with a large diameter cylinder chamber 91 formed in the center and a pair of small diameter cylinder chambers 92a and 92b formed on both sides, and a piston with a diameter corresponding to the cylinder chamber 91 in the center. It has a cylinder chamber 9 on both sides.
A piston 95 having a piston portion 95b having a diameter corresponding to 2g and 92b is slidably provided. Further, piston rods 96a and 96b are connected to piston ends on both sides, respectively. A left chamber 97a and a right chamber 97b, which receive in-phase outputs, are formed in a portion of the cylinder chamber 91 that is partitioned by the piston portion 95a and has a large cross-sectional area. Furthermore, the cylinder chambers 92a and 92b, which are aligned with the chambers 97a and 97b, have a small cross-sectional area so as to receive the phase output. This cylinder 94 is fixed to the cross member 83 with its axial direction defined in the left-right direction. The left piston rod 96a is connected to the pivot shaft 39 of the left intermediate joint 38, and the right piston rod 96b is connected to the pivot shaft 39 of the right intermediate joint 38. 82a and 82b can be steered.

The left chamber 97a of this rear power cylinder 90,
The right x97b is connected to a control valve 98 for the same phase via an oil passage 99, and the cylinder chambers 92a, 92b of the rear power cylinder 90 are connected to a control valve 100 for phase via oil passages 101a, 101b. There is.

A spool valve as shown in FIG. 2 is used as the in-phase control valve 98.

Specifically, the spool valve has a cylindrical case 1
02, a spool 221 whose both ends are biased by a pair of springs 220 is provided. On the outer periphery of this spool 221, two annular grooves 222 and 223 are arranged in parallel.

Further, on both sides of the circumferential wall of the case 102 facing the spaces of the grooves 222.degree.
At the center of the peripheral wall of the case 102 facing the space 223, actuator side ports 226 and 227 are provided, respectively. Pilot boats 228 are provided at both ends of the case 102 for applying control pressure to the ends of the spool. ．． 229
The structure is equipped with Then, the actuator side boats 226 and 227 are connected to the oil flow path 99.

The pilot ports 228 and 229 of this in-phase control valve 100 are connected to each left chamber 18 of the power steering 6, respectively. When the right chamber 19 is connected via the oil passage 103 and power steering pressure is generated, the spool 221 in the neutral state is displaced and the reserve side boats 224a, 224b
and the pump side boats 225a, 225b. And control valve 100
An oil pump 105 is connected to each of the pump-side boats 225a and 225b, which is driven by the differential gear 104 and generates oil pressure according to the vehicle speed (higher vehicle speed: more oil pressure). This makes it possible to supply hydraulic pressure depending on the vehicle speed and the number of times the spool 221 moves to the left chamber 97a or the right chamber 97b in the steering direction of the rear power cylinder 90. That is, depending on the steering state of the front wheels 1a and lb,
a.

The rear wheels 82a and 82b can be steered in the same direction as 1b (in-phase steering means). Note that each reserve side boat 224a, 224b is connected to the reserve tank 106 receiving the return of the power steering 6.

Further, the phase control valve 100 uses a spool valve type four-port throttle switching valve. The schematic structure of this switching valve is shown in FIGS. 3 and 4. However, FIG. 4 shows a conceptual diagram of the switching valve.

To explain the switching valve, 107 is a cylindrical case with pilot pressure boats 108 and 109 on both sides, and 110 is a spool provided within this case 107. Both ends of the spool 110 are slidably supported by bearings 111 formed on the inner surface of the case, allowing the entire spool to slide in the axial direction of the case 107. A pair of springs 112 and 113 are interposed between the spool end and the case end, respectively, to position the spool 110. This spring 112
, 113 on the outside of the bearing section communicates with the boats 108, 109. These boats 108 and 109 are connected to the oil flow path 10 through a branch path 132.
It is connected to the middle part of 3, and applies power steering pressure, which serves as control pressure, to the spool end.

Further, the inner cavity portion of the case 107 sandwiched between the bearing portions 111 has a large diameter. A sleeve 114 having an outer diameter corresponding to the inner cavity is slidably provided at the center of the spool portion exposed to the large space. This sleeve 1
The ends of the sleeve 14 are biased by a pair of springs 115 and 116 fixed to the spool 110 to position the entire sleeve on the spool 110. and,
Pressure receiving chambers 117 and 118, which also serve as spring chambers, are formed in each space formed at the end of the sleeve.

On the outer circumferential surface of the spool 110 covered with the sleeve 114, two chambers 119 and 120 each formed of an annular groove are arranged side by side. Further, the inner peripheral surface of the sleeve 114 has a chamber 1.
Three chambers 121 to 123 each formed of an annular groove are provided at the boundary between the two chambers 19 and 120. The chambers 119 and 120 are passage spaces 124 and 125 formed in the sleeve 114 and the inner peripheral surface of the case, respectively.
The actuator boats 126 and 127 are connected to actuator boats 126 and 127 bored on the outer circumference of the case. And boat 126
, 127 is the oil flow path 101a-.

101b. Further, the chamber 122 is the passage space 12
Boat 12 for oil supply provided in case 107 via 8
It is connected to 9. The boat 129 is connected via an oil supply path 130 to a discharge portion of a constant flow type oil pump 131 that is driven by the engine 20 together with the oil pump 13 . Specifically, oil pump 1
31 has a discharge flow rate as shown in FIG. 8, so that a constant flow rate of oil can be supplied to the boat 129.

In addition, the remaining chambers 121 and 123 each have a sleeve 114
and passage spaces 133, 13 formed on the inner peripheral surface of the case.
Through 4, there is a boat 1 for the reservoir drilled on the outer periphery of the case.
It is connected to 35.136. And these boats 1
35 and 136 are connected in parallel through an oil passage 137 and connected to the reservoir tank 106. Pressure receiving chambers 117 and 11g on both sides of the sleeve are connected in parallel to this parallel oil passage 137 via communication passages 138 and 139, respectively, and oil from the oil pump 131 is supplied to the pressure receiving chambers 117 and 11g.
It is designed to allow access to 18 people.

Each of the communication passages 138 and 139 is also provided with a check valve 14 for regulating the flow toward the reservoir tank 106.
0 is set. Further, a variable orifice 141 (or a variable choke) is provided between the communication passage between the check valve 140 and the reservoir port 135 and the communication passage between the check valve 140 and the reservoir boat 136. An interposed communication path 142 for generating a differential pressure is connected. The variable orifice 141 is connected to a vehicle speed-sensitive pressure generator 143 built into the differential-driven oil pump 105, and is variable with a pilot pressure as shown in FIG. 9 generated from the vehicle speed-sensitive pressure generator 143. The amount of restriction of the orifice 141 can be varied in response to vehicle speed.

Specifically, the vehicle speed sensitive pressure generator 143 has a fixed orifice (not shown) in the discharge part of the oil pump 105 that rotates in proportion to the vehicle speed, and uses the differential pressure before and after the fixed orifice as a pilot pressure, and uses this as a pilot pressure. The structure is such that the information is transmitted to the variable orifice 141 through the .

As a result, the control valve 100 determines the rate of change of the pilot pressure of the power steering 6 ( It is possible to generate hydraulic pressure according to the phase (higher vehicle speed: lower hydraulic pressure) depending on the steering wheel steering angular speed) and vehicle speed. That is, at the start of a steering operation, the control valve 100 outputs an output from the rear power cylinder 90 according to the speed of change in the steering state of the front wheels as an output for steering the rear wheels 82a, 82b in the opposite direction to the front wheels la, lb. It is arranged so that it can be supplied to the cylinder chamber 92a or the cylinder chamber 92b (reverse phase steering means).

In this way, the steering angles of the rear wheels 82a and 82b are determined from the combined force of the in-phase steering means and the anti-phase steering means provided in parallel.

The oil flow paths 101a and 101b connected to the phase control valve 100 are connected to the branch paths 145 and 14.
5 to the plugs 54 and 56 of the phase advancement mechanism 14, and uses the phase control valve 100 as a common control means to control the front wheels la at the same time as the rear wheels 82a and 82b.

1b can be advanced to the additional turning side (depending on the pilot pressure input to the rear power cylinder 90).

Next, the operation of the four-wheel steering system configured as described above will be explained.

When the vehicle is traveling straight, the steering wheel 17 is in a neutral state, so the front wheels 1a, lb and the rear wheels 82a,
82b faces the straight direction.

When the steering wheel 17 is turned, for example, to the right (at medium to high speeds) in order to turn (turn-in) from such a straight-ahead state, the steering wheel 17 changes momentarily depending on the steering angular velocity and vehicle speed relative to the turned steering angle. Rear wheels 82a, 82
b is in the opposite phase, and the steering angles of the instantaneous wheels 1a and lb increase from the input steering angle.

Specifically, when the steering wheel 17 is operated, this rotation is caused by the column shaft 16. Intermediate joint 15. The first stage planetary gear mechanism 2 is connected via the input shaft 24.
The signal is transmitted to the sun gear 25 of No. 1. Here, the ring gear 26 receives the operating force, but since the ring gear 26 is fixed to the case 37 with a set screw, its rotation is further transmitted to the planetary gear 31 of the second stage planetary gear mechanism 22 via the planetary gear 27. To go.

The ring gear 31 of the second-stage planetary gear mechanism 22 also tries to rotate due to the operating force, but the ring gear 31 has a restoring force generated by the control valve 23 that always tries to return the ring gear 31 to its original position. Since the hydraulic pressure generated by the oil pump 13 (the force that always tries to make the relative displacement of the sleeve 69 to zero with respect to the spool 53) acts as an operation reaction force, the rotation of the planetary gear 31 is directly transmitted from the sun gear 28 to the valve input. It is transmitted to the shaft 7a and the torsion bar 8. As a result, the rotation transmitted to the torsion bar 8 is transmitted to the pinion 5, and the front wheels 1a, lb are steered in the direction of the steering wheel 17. At the same time, the rotary valve 7 is operated by the rotation transmitted to the valve input shaft 7a, and the hydraulic pressure generated by the oil pump 13 is supplied to the right chamber 19 of the power cylinder 11, and the steering wheel 1
We will assist you with the operations in step 7.

On the other hand, the spool of the control valve 98 for the same phase is stroked in accordance with the power steering pressure of the power steering 6. The oil discharged from the oil pump 105 is controlled by the stroke of this Subur. That is, the control valve 98 generates oil pressure corresponding to the vehicle speed (rear wheel rotational speed) and the power steering pressure, that is, the steering state of the front wheels 1a, lb. This oil pressure then steers the left chamber 97 of the rear power cylinder 90 to the same phase side.
It flows into a.

On the other hand, when the power steering pressure is applied as a pilot pressure to the phase control valve 100 from the pilot pressure port 109, the spool 110 is displaced to the left (xl) by an amount proportional to this pressure.

Since this amount of displacement is related to the product of the area of the end surface of the spool 110 and the pilot pressure and the elastic force of the springs 112 and 113, the following relational expression holds true for both.

al @Fl-KI IIxl+f1 In other words, it is expressed as Xi ma+ -p, ft /Kt. However, al is the area of the spool end surface.

K is the spring constant of springs 115 and 116.

fl is the preload value of the spring + Fl is the pilot pressure.

At this time, due to the displacement of the spool 110, the sleeve 1
14 also tries to move in the same direction. This includes pressure receiving chamber 117
It is necessary for the oil to move to the pressure receiving chamber 118 through the communication path 142. However, the variable orifice 1 in the communication path 142
41 is built in, so at this time, the variable orifice 1
A differential pressure ΔP occurs before and after 41. Here, ΔP is expressed as follows.

ΔP-δ・Qb2/2・Cd'd2 However, δ is the fluid density, Qb is the flow rate flowing through the constriction, d is the cross-sectional area of the ridge, and Cd is the flow coefficient.

In addition, in the case of a choke structure, ΔP-8·π·μ·fI/d2. However, g is the length of the constricted portion, and μ is the viscosity coefficient of the oil.

Then, due to this differential pressure ΔP, the sleeve 114 causes a relative shift to the right with respect to the spool 110. At this time, the displacement y versus t1 is expressed as y-ΔP-b2-f2/2. However, b2 is the area of the end surface of the sleeve, 2 is the spring constant of the springs 112 and 113, and f2 is the preload value of the springs.

A constant flow of oil generated by the oil pump 131 is supplied from the oil supply port 129 (since the oil is co-supplied, a relative change is made from the actuator ports 126 and 127).
A pressure difference proportional to is generated.

That is, since the relative displacement y is a function of yocΔP"Qb", 1)-1/d2, Qb-b2 (xl-y)/l where t is time.

Therefore, from the actuator ports 126 and 127, the output decreases according to the vehicle speed, and the hydraulic pressure (change rate of the steering state of the front wheels 1a, lb) is controlled in proportion to the time rate of change in the power steering pressure (the rate of change in the steering state of the front wheels 1a, lb). differential pressure) is output.

This oil pressure (differential pressure) is then applied to the rear power cylinder 90.
The rear wheel 82a is located in the cylinder chamber 92b.

82b, and is supplied as an output to phase the phase advancing mechanism 14.
The output is supplied to the plug 54 as an output that increases the steering angle of the front wheels 1a and 1b.

As shown in FIG. 11, these rear wheels 82a, 8
2b in the opposite direction to the front wheels and the rear wheels 82a.

The rear power cylinder 90 opposes the output of the left chamber 97a which attempts to steer the rear wheels 82b in the same direction as the rear wheels. However, as shown in FIG. 12, the rear wheel steering angle on the opposite phase side is obtained by the combined output.

Then, the rear wheel 82a is adjusted according to this rear wheel steering angle.

82b is being steered.

On the other hand, in the phase advancing mechanism 14, when control pressure is applied to the plug 54, the spool 53 slides to the right in proportion to the oil pressure as shown by the arrow in FIG. Then, due to the restoring function performed by the oil pressure of the oil pump 13, the sleeve 69. The collar 68 follows the spool 53 and moves to a position where the relative position with respect to the spool 53 is zero. This sleeve 69. As the collar 68 moves, the lever 60 rotates around the plate 64 as a fulcrum. This causes the ring gear 29 to rotate clockwise. Here, since the planetary gear 27°31 is fixed by the steering wheel 17 held by the driver,
The rotation of the ring gear 29 is transmitted to the valve input shaft 7a and the torsion bar 8, and the steering angle of the front wheels 1a, lb is increased as shown in FIG.

The reverse phase according to the operation angular velocity (change speed of the steering state) is carried out according to the control block of FIG.
Through phase advance control, a sharp oral quality is produced.

Then, at the next moment, as the speed of change of the steering wheel 17 disappears, the original steady state four-wheel in-phase steering (front wheel steering by the power steering 6 and power steering pressure) returns.

Enter normal in-phase four-wheel steering (4WS) with rear wheel steering according to vehicle speed,
Stabilize the movement of the car. As a result, turning is performed.

Note that, as shown in FIG. 14, when the steering wheel 17 is returned to its original position or when the steering wheel is turned to the left, the operation is reversed.

By setting the bridal values of the springs 115 and 116 of the phase control valve 100, when the steering wheel 17 is slowly steered, phase control is not performed, but normal in-phase four WS is performed.

Therefore, the front wheels 1a and lb are advanced and the rear wheel 82a is
, 82b by a common control means, the control balance between the front and rear wheels will not be lost. In other words, the phase control that balances lateral acceleration and yaw rate by setting the front wheels la and lb in phase and making the rear wheels 82a and 82b in reverse phase will correct the unbalance between yaw motion and lateral motion if the operating phase shifts. However, the common control means can easily operate them simultaneously at a constant ratio, so that control can be balanced under any circumstances.

Moreover, the in-phase control valve 9 is installed in parallel.
Since the rear wheel steering angle is obtained by the combined output of the in-phase steering means using the control valve 8 as the control source and the anti-phase steering means using the phase control valve 100 as the control source, it is possible to control the phase inversion control compared to a single one. becomes simpler.

In addition, even in the event of a failure, the front and rear wheels fail at the same time, so there is the advantage that the normal two-WS function is ensured.

Further, the present invention is not limited to the first embodiment, but also applies to the second embodiment shown in FIGS.
The third embodiment shown in the figure, the fourth embodiment shown in Figs. 21 to 23, the fifth embodiment shown in Figs. 24 and 25, the sixth embodiment shown in Fig. 26, A seventh embodiment shown in FIG. 27 may be used.

That is, the second embodiment does not use the variable orifice 141 described in the first embodiment, but instead supplies hydraulic pressure according to the vehicle speed to the phase control valve 100.

Specifically, instead of the variable orifice 141, a fixed orifice or a fixed choke (not shown) is provided in the hydraulic circuit of the phase control valve 100. The oil pump 105 is also provided with a flow rate control valve 150 that controls the flow rate based on the differential pressure across an orifice (not shown) provided in the oil pump 105. And this 1WEf
An engine-driven oil pump 131 is connected to the inlet side of the fi control valve 150. The outlet side of the flow control valve 150 is connected to the port 129 of the phase control valve 100, and the flow rate control valve 150 controls the constant flow of oil from the oil pump 131 to a flow rate according to the vehicle speed. The water is supplied to the control valve 100. Note that FIG. 16 shows the flow rate characteristics at the inlet of the flow rate control valve 150, and FIG. 17 shows the flow rate characteristics at the outlet of the flow rate control valve 150.

In the third embodiment, a pressure feedback type servo valve 160 is used instead of a phase control valve, and this servo valve 160 is controlled by a CPU 161 on a steering wheel 17.
electrically controlled according to the steering wheel angular velocity and vehicle speed.
The control pressure (differential pressure) required for phase (inversion) and phase advancement is obtained.

Specifically, as the pressure feedback type servo valve 160, a force smoke direct acting servo valve as shown in FIG. 19 is used. That is, 162 is the valve body. A movable spool 163 is slidably held within this valve body 162 by a spring 164. A driving voice coil 16 is attached to one side of the movable spool 163.
4 is placed. A magnet 165 and a yoke 166 are provided in the gap of the valve body 162 to form a constant magnetic field, and when a control current is passed through the voice coil 164, a driving force is generated depending on the magnitude and direction of the current.
A feedback cylinder 167 balances the load pressure. And the movable spool 16
A sleeve 168 is provided around the movable spool 163, and constitutes a four-way guide valve that can control the pressure and flow rate according to the displacement of the movable spool 163. A metering type oil pump 131 is connected to the groove in the center of the sleeve of this force motor direct drive servo valve, and oil flow paths 101a and 100 are connected to actuator boats 169 and 170 provided in the valve body 162.
1b is connected. Note that the grooves on both sides of the center of the sleeve are connected to the reserve tank 106.

On the other hand, the CPU 161 has the steering wheel 1
A steering wheel angular velocity sensor 171 provided on the column shaft 16 of No. 7 and a vehicle speed sensor 172 for detecting vehicle speed are connected. The output side of this CPU 161 is connected to the pressure feedback type servo valve 160. Then, depending on the input steering wheel angular velocity and vehicle speed signals,
The PU 161 outputs a current value necessary for phase inversion and phase advancement to control the differential pressure between the actuator boats 169 and 170 in the same manner as in the first embodiment. However, FIG. 20 shows the relationship between the differential pressure ΔP and the current value l.

Note that a leaf valve 200. is provided in the hydraulic circuit between the pressure feedback type servo valve 160 and the oil pump 131. A pressure switch 201 is provided. Further, a pressure switch 202 is provided at the discharge portion of the oil pump 105, and constitutes a fail-safe function. That is,
Both devices are connected to the CPU 161, and when abnormal pressure is detected from the pressure switches 201 and 202 (
(In-phase system hydraulic failure, 1-phase hydraulic abnormality, etc.)
, the signal of the relief valve 200 is set to rO by the command of the CPU 161.
FFJ is set, the supply to the pressure feedback type servo valve 160 is cut off, and the mode is switched to the normal in-phase 4WS mode.

The fourth embodiment is based on the input shaft 2 of the phase advance mechanism 14.
4 is provided with a steering sensor 180 for detecting the steering angle measurement, and the steering sensor 180 is provided with a steering sensor valve 1.
81 is provided to obtain the control pressure necessary for phase (inversion) and phase advancement.

Specifically, as shown in FIG. 22, the steering sensor 180 includes a viscous coupling (viscous clutch) 182 provided on the outer periphery of the input shaft 24, with the inner periphery as the input side and the outer periphery as the output side. It has a similar structure. As a result, when the steering wheel 17 is steered, rotational torque corresponding to the steering angular velocity is applied to the inner case 184 of the viscous coupling 182, the plurality of plates 185 on the input/output side, It is designed to be outputted from the outer case 187 through the clutch plate 186.

Further, the steering sensor valve 181 is shown in FIGS.
As shown in FIG. 3, an elongated valve chamber 188 is provided in a peripheral wall portion of the case 37 of the phase advancing mechanism 14 adjacent to the viscous coupling 182 in a direction perpendicular to the axis of the viscous coupling 182. A part of the center of the valve chamber 188 is exposed to the outer circumferential surface of the outer case 187 of the viscous coupling 182, and a pin 189 protruding from one location on the outer circumferential surface of the outer case 187 is inserted. This pin 189
A pair of pistons 190 and 191 are slidably provided in the valve chamber 188 so as to sandwich the pistons 190 and 191.
91 is urged toward the pin by a pair of springs 192. Then, when the viscous coupling 182 is not displaced, the pistons 190 and 191 are communicated with a reservoir boat 194 similar to the oil supply boat 193 provided in the case 37, and as the pistons 190 and 191 are displaced, both In addition to blocking the hydraulic flow path between the boats, the left and right boats 195 for the actuator provided in the case 37,
It has a structure in which a group of grooves 197 are provided for opening and closing 196. In this way, control pressure is generated from the boats 195, 196 according to the steering direction and the steering angular velocity.

An oil supply boat 193 is connected to a constant flow type oil pump 131. In addition, an actuator boat 194 is connected to the rear power cylinder 9 via an oil supply path 199.
0 cylinder chamber 92a.

92b. Furthermore, the middle of the oil supply path 199 is connected to the plugs 54 and 56 of the phase advance mechanism 14 via a branch path 199a.
is connected to the phase advance mechanism 14 and the rear power cylinder 90 to apply control pressure according to the generated steering direction and steering angular velocity.
The pressure is supplied as leading and reversed phase pressure. In this embodiment, the power steering oil pump 13 is directly connected to the rotary valve 7.

The fifth embodiment is a piston 12 of a power steering 6.
This system uses a dashpot 210 that operates together with the phase control valve 100a, which uses a valve having the same structure as the in-phase control valve, to generate control pressure according to the steering wheel steering angular velocity and vehicle speed. be.

Specifically, the rod 211a of the piston 211 of the dashpot 210 is connected to the piston rod 12a of the power steering 6. And this dashpot 21
Chambers 212a, 2 formed on both sides of the piston 211 of
A communication path 2 with a fixed orifice 213 interposed between 12b
Connect with 14. As a result, a pressure difference corresponding to the steering angular velocity is generated from each chamber 212a, 212b of the dashpot 210. Each chamber 212a, 212b of this dashpot 210 is connected to the spool end side of the phase control valve 100a. Further, an oil pump 215a, which is driven by the differential gear 104 and has a characteristic that the flow rate decreases as the rotational speed (vehicle speed) increases, is connected to the oil pump 105, as shown by the broken line in FIG. The discharge part of the oil pump 215a is connected to the pump side boat of the control valve 101a, so that the control valve 100a generates hydraulic pressure according to the steering angular velocity and the vehicle speed. Of course, this oil pressure is supplied to the cylinder chambers 92a and 92b of the rear power cylinder 90. In this embodiment, the pump driven by the engine 20 is only for power steering.

The sixth embodiment is a modification of the fifth embodiment, in which the power steering pressure from the chambers 18 and 19 of the power steering 6 is supplied to the chambers 212a and 212b of the dashpot 210, and the power steering pressure is adjusted according to the steering angular velocity and the vehicle speed. It is designed to generate hydraulic pressure. In order to prevent the chamber on the opposite side from the movement of the piston 211 from becoming negative pressure, the communication passage 214 is provided with a curved supply circuit consisting of an oil supply passage 216 having two check valves 215 and 215.

The seventh embodiment is a modification of the sixth embodiment, in which a variable orifice 2 is used instead of the fixed orifice of the dashpot 210.
17 will be provided. And differential drive oil pump 105
Alternatively, a vehicle speed-sensitive pressure generator 218 having a structure similar to that of the first embodiment described above is provided in the hydraulic circuit, and the throttle amount of the variable orifice 217 is controlled by the generated pilot pressure (differential pressure) before and after the fixed orifice. It is made to be able to change depending on the situation.

Note that in the first to seventh embodiments, the first
Components that are the same as those in the embodiment shown in FIG.

[Effects of the Invention] As described above, according to the present invention, the front and rear wheels can be actively controlled by the common control means without disturbing the control balance between the front and rear wheels. Moreover, since the rear wheel steering angle is obtained by the combined output of the in-phase steering means and the anti-phase steering means provided in parallel, phase reversal control can be simplified.

[Brief explanation of the drawing]

1 to 14 show a first embodiment of the present invention, FIG. 1 is a configuration diagram showing a four-wheel steering system to which the rear wheel steering system of the invention is applied, and FIG. 2 is a control for in-phase control. 3 is a sectional view showing a phase control valve, FIG. 4 is a schematic diagram of the control valve, FIG. 5 is a partially cutaway perspective view showing a phase advance mechanism, and FIG.
The figure is a sectional view showing the two sets of planetary gear mechanisms, and Figure 7 is a sectional view showing the structure of the control valve of the phase advance mechanism.
Figure 8 is a diagram showing the characteristics of an engine-driven constant flow oil pump, Figure 9 is a diagram showing the characteristics of the pilot pressure generated from the vehicle speed sensitive pressure generator, and Figure 10 is a diagram showing phase advance control. , Fig. 11 is a diagram showing phase control, Fig. 12 is a diagram showing the resultant force, Fig. 13 is a block diagram showing control forms of phase advance control and phase control, Fig. 14 is a diagram showing left and right handles. Figure 15 is a diagram showing the main part of the second embodiment of the present invention, and Figure 16 shows the characteristics at the inlet of the flow control valve. The diagram, Figure 17, is the diagram showing the characteristics at the exit, Figure 1.
FIG. 8 is a configuration diagram showing the main parts of the third embodiment of the present invention, FIG. 19 is a sectional view showing a pressure feedback type servo valve,
FIG. 20 is a diagram showing the characteristics of the pressure feedback type servo valve, FIG. 21 is a configuration diagram showing the main part of the fourth embodiment of the present invention, and FIG. 22 is a sectional view showing the structure of the steering sensor. Figure 23 is a cross-sectional view showing the steering sensor valve;
Fig. 4 is a block diagram showing the essential parts of the fifth embodiment of the present invention, Fig. 25 is a diagram showing the characteristics of the hydraulic pressure supplied to the control valve for that phase, and Fig. 26 is a diagram showing the characteristics of the hydraulic pressure supplied to the control valve for the phase. FIG. 27 is a block diagram showing the main parts of the seventh embodiment of the present invention. la, lb--front wheel, 14--phase advance mechanism, 82a. 82b...Rear wheel, 90...Rear power cylinder, 9
8... Control valve for in-phase, 100... Control valve for reverse phase. Applicant's agent Patent attorney Takehiko Suzue I1 and X blade 9 Figure Figure 9 Extenuating figure Figure Figure Figure Nose Figure 2

Claims (1)

[Claims] an in-phase steering means for steering the rear wheels in the same direction as the front wheels; an anti-phase steering means provided in parallel with the in-phase steering means for steering the rear wheels in the opposite direction to the front wheels at the start of a steering operation; 1. A steering device for a vehicle, comprising: a phase-advancing steering means that increases the steering angle; and a control means that commonly controls operations of the phase-advancing steering means and the anti-phase steering means.