JPH02124370A - Steering gear ratio changing device - Google Patents

Abstract

PURPOSE:To have phase advance control of front wheels using a simply constructed steering gear ratio varying device, in which the steering angle of car is variable with respect to the operation angle of the steering wheel, by displacing a sleeve in followup after a spool axially displaced in accordance with the control pressure to be applied from one of the two control ports. CONSTITUTION:In a power steering as embodiment of the present invention, a steering wheel 17 is coupled with the input shaft 7a of a rotary valve 7 for controlling supply/exhaust of the oil pressure to a power cylinder device for steering of the front wheels through a column shaft 16 and a steering gear ratio varying device 14 as phase advance mechanism. The steering gear ratio varying device 14 is equipped with two sets of planetary gearing mechanisms 21, 22 and a control valve 23. This control valve 23 displaces a spool 53 by a control pressure to be impressed on one of the control ports 54a, 56a, and ring gear 29 of the planetary gearing mechanisms 21, 22 is to be displaced with displacing sleeve 69 in followup to said displacement with the aid of a lever 60.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable steering gear ratio device that varies a vehicle steering angle relative to a steering wheel steering angle of a vehicle.

(Prior Art) In four-wheel steering, it has been found that controlling the steering angles of the front and rear wheels improves the dynamic characteristics during turns.

That is, at the start of steering, the rear wheels are momentarily turned to the opposite phase side, 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, the next moment, it returns to steady four-wheel in-phase steering, allowing the vehicle to turn along the desired trajectory while keeping the sideways angle at zero.

In order to realize such front wheel phase advance control, a variable steering gear ratio device that can vary the vehicle steering angle relative to the steering wheel steering angle is employed.

Conventionally, devices that can vary the steering gear ratio include Japanese Patent Application Laid-Open Nos. 48-31636, 53107036, 62-26162, and 54-3.
4212, Japanese Patent Publication No. 56-45824, etc.

In each of these devices, one or two sets of planetary gear mechanisms are provided between an input shaft connected to a steering wheel and an output shaft connected to a steering gear. Further, a worm is provided on the ring gear of this first set of planetary gear mechanisms or the second set of planetary gear mechanisms, and a worm gear directly connected to the motor is meshed with the worm. When the steering wheel is operated, its rotation is transmitted to the output shaft via the planetary gear mechanism, and if the motor is operated from this state to rotate the ring gear, the gear ratio is varied by the rotational displacement of the ring gear. It looks like this.

(Problem to be Solved by the Invention) By the way, although such a ring gear displacement mechanism that combines a motor-driven worm gear and a worm can prevent the ring gear from moving accidentally by using the self-locking function of the worm gear, Since the gear ratio cannot be obtained unless the ring gear is rotated to a predetermined displacement with high precision, control becomes quite complicated. Moreover, since it is controlled electrically, it suffers from poor reliability against noise, radio wave interference, and the like.

This invention was made in view of the above circumstances, and its purpose is to provide a variable steering gear ratio device that can perform phase advance control with simple and highly reliable control. (((It is to do.

(Means for Solving the Problems) In order to achieve the above object, the variable steering gear ratio device of the present invention includes a valve body and a ring gear displacement mechanism that displaces a ring gear in the rotational direction. A spool freely provided, a sleeve slidably provided on the outer periphery of the spool, a fluid inlet boat and a fluid outlet boat for steering reaction force provided on the valve body, and a sleeve provided on the end surface side of the sleeve. Flow control between a pressure receiving chamber with a sleeve end facing, the spool and the fluid inlet port and the fluid outlet port provided on the spool and each of the pressure receiving chambers according to the relative displacement of the spool and the sleeve. an opening/closing passage for orienting the sleeve with respect to the spool; a transmission member provided in the valve body for transmitting the displacement of the sleeve to the ring gear of the planetary gear mechanism; and a control for displacement of the ring gear provided in the valve body and at the end of the spool. It consists of a pair of control pressure ports for inputting pressure.

(Function) According to the variable steering gear ratio device of the present invention, in steady state, the relative position of the sleeve and the spool is maintained by fluid flow control so that the position of the sleeve is zero with respect to the spool. This tracking performance outputs a steering reaction force that always keeps the ring gear of the planetary gear mechanism in a predetermined position.

If a control pressure with a variable gear ratio is applied from one side of the control pressure boat, the spool will surface in the axial direction according to the control pressure. Then, the sleeve is displaced following this displaced spool so that the relative position maintains a zero relationship, and the ring gear of the planetary gear mechanism is displaced via the transmission member. As a result, the front wheels can be controlled in phase with simple control using fluid pressure that is free from noise and other obstacles.

(Example) The present invention will be described below based on an example not shown in FIGS. 1 to 7. FIG. 5 shows a four-wheel steering system for a vehicle to which the present invention is applied, and 1a and 1b are left and right front wheels. The front wheels 1a, lb are rotatably supported by knuckles 2a, 2b which are supported to be swingable in the horizontal direction relative to a vehicle body (not shown). Further, the knuckles 2B, 2b are 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, via tie rods 3a, 3b. That is, the power steering 6 is connected to the rack 4. A steering gear assembly 9 comprising a pinion 5° rotary valve 7 and a torsion bar 8 is connected to a power cylinder device 10 for steering connected to a rotary valve 7 (a power cylinder 11 is provided with a piston 12 connected to a rack 4). and,
It is combined with an engine-driven oil pump 13 (for power steering) that supplies hydraulic pressure to the rotary valve 7. And piston rods 12a on both sides of the piston 12 of the power cylinder device 10.

12b is connected to the tie rods 3a and 3b.

It also serves as a force 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 are provided with a variable steering gear ratio device 14, which serves as a phase advance mechanism to be described later. A steering wheel 17 is connected via an intermediate joint 15° column shaft 16. 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, left chambers 18 are formed on both sides of the piston 12. Hydraulic pressure generated by the oil pump 13 is supplied to the right chamber 19 through the rotary valve 7, 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 variable steering gear ratio device 14, as shown in detail in FIGS. and a control valve 23 (corresponding to a ring gear displacement mechanism).

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, which is fixed to the case 9a and constitutes the body of the variable steering gear ratio device 14. In the upper side of this case 37, the input shaft 24 (corresponding to an input shaft) is connected to the valve input shaft 7a (
It is rotatably provided coaxially with the output shaft (equivalent to the output shaft). Note that 24a is a bearing that rotatably supports the input shaft 24. input shaft 24
A sun gear 25 is integrally provided on the lower outer periphery of. A ring gear 26 supported by the case 37 is provided around the sun gear 25. Between the ring gear 26 and the sun gear 25, four sets of planetary gears 27 that mesh with both gears are provided, forming the -th stage planetary gear mechanism 21. The intermediate joint 15 is connected to the upper part of the input shaft 24 protruding from the cap 37a.

Also, the end of the valve input shaft 24 is connected to the case 9a.
It protrudes upward from the upper end opening. A sun gear 28 having the same specifications as the planetary gear 21 of "-stage 1" is integrally provided on the outer periphery of the end of the valve input shaft 24 that enters the case 37. Further, a ring gear 29 having the same specifications as the negative stage is provided in the case 37 surrounding the sun gear 28. A shaft 30 is interposed between the ring gear 29 and the sun gear 28.

Four sets of rotatable planetary gears 31 coaxially connected to the -stage planetary gear 27 are provided, and constitute a second stage planetary gear mechanism 22.

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, 41 is a ring gear 26,
This is a spacer for regulating the movement of 29 in the vertical direction.

Further, the tip end of the valve input shaft 7a is inserted into a recess 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 steered with the ring gears 26 and 29 fixed, the steering angle of the steering wheel 17 is changed. It is possible to transmit the same ratio to the rotary buff 14 and the torsion bar 8 through the planetary gear mechanisms 21 and 22 of the first and second stages. However, a metal bushing 45 is interposed between the insertion end of the valve input shaft 7a and the recess 43 to prevent rattling in the circumferential direction.

Further, the - stage planetary gear mechanism 21 is provided with a safety device 46 that prevents 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 pin part 48 that fits into the four parts 47 and the convex part. A set screw composed of a spring 49 and an adapter part 50 is provided to bias the pin part 48 in the fitting direction. With this structure, the movement of the ring gear 26 in the rotational direction is regulated by fitting the concave and convex portions, and when an excessive steering force exceeding the preload from the steering wheel 17 enters the ring gear 29, the movement of the concave and convex portions of the ring gear 26 is prevented from being released. The planetary gear mechanism 21 rotates the ring gear 26.
．． 22 from excessive torque. In addition,
As shown in FIG. 4, the input shaft end and the valve input shaft end that are in the fitted state include a pair of fan-shaped protruding pieces 7b, 7b and a pair of protruding pieces 7b, which are loosely fitted between the protruding pieces 7b, 7b. A stopper part 14a configured in combination with the protruding pieces 24a, 24a is provided, and when the ring gear 26 rotates a certain amount, the protruding pieces 7b and 24
a are in contact with each other so that the steering force from the steering wheel 17 is directly transmitted from the input shaft 24 to the valve input shaft 7a.

A case 37 in which such a planetary gear mechanism 21, 22 is assembled
A la control valve 23 is assembled to the.

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 connected to a plug 54 installed at 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 (corresponding to control pressure ports) of the plug 54, 56. Also adapter 55
A spring chamber 55a is formed inside. and,
In this spring chamber 55a, a hook is provided between a washer 56a fitted into the small diameter part 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 part 53a. A spring 58 is housed therein, and the spring 58 positions the spool 53. Five nuts are used to prevent the plugs 54, 56 and the adapter 56 from loosening.

Further, a plate-shaped lever 60 (corresponding to a transmission member) is provided on the outer periphery of the spool 53, movably penetrating the shaft portion of the spool 53. The lever 50 is arranged on a line that intersects the axis of the ring gear 29 at right angles. and,
The circular arc portion formed at the end of the lever 60 on the ring gear 29 side is connected to the through hole 6 formed in the valve body portion and the case portion.
1 and formed on the outer peripheral surface of the ring gear 29.
2 is engaged. In addition, the arcuate portion formed at the remaining narrow end of the lever 60 extends over the valve chamber 52 so as to cover the end.
The plate 6 provided on the inner bend of the adapter 63 attached to the
4, and is rotatably engaged with the groove 65 of the spool 53, so that the entire lever can be rotated 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. Collar 68 and sleeve 69 connect their outer ends to plug 54 . Elastic force (preload) of springs 7Qa and 70b provided between adapter 55
is pressed against both sides of the lever 60, and the sprue 5
Three parts including the lever 60 are positioned on the top of the lever 60. 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, there are three outflow side chambers 73 to 73 formed by grooves, located at the boundary between the chambers 71 and 72.
75 (both of which correspond to opening/closing passages) are provided. The chamber 71 is connected to a passage 76 provided inside the spool 53.
It communicates with a pressure receiving chamber 77 formed between the collar 68 and the plug 54, which also serves as a spring chamber, via a (corresponding to an opening/closing passage). Further, the chamber 72 is connected to the sleeve 6 via a passage 78 (corresponding to an opening/closing passage) similarly provided inside the spool 53.
9 and the adapter 55 and communicates with a pressure receiving chamber 79 that also serves as a spring chamber. The central chamber 74 on the outflow side is connected to the discharge section of the oil pump 13 via a port 80 (corresponding to a fluid inlet boat) provided in the valve body 51. The remaining chambers 73 and 75 are connected to the rotary valve 7 of the steering gear assembly 9 through a port 81 (corresponding to a fluid outlet port) provided in the valve body 51.
A follow-up type servo that is connected to an inlet port (not shown) of the oil pump 13 and can use hydraulic pressure generated by the oil pump 13 to hold the ring gear 29 in a predetermined position or increase the input steering angle. It constitutes a valve (spool valve). That is, the oil pump 1 is connected to the pressure receiving chamber 77.79 facing the sleeve end through the passage 76.78.
Since the structure is such that the oil of No. 3 flows in, when the second stage ring gear 29 is rotationally displaced by steering and the sleeve 69 is displaced in the axial direction, the chambers 71 and 72 and the chambers 73 to 75 open and close.
The passage on the side of the displaced pressure receiving chamber opens and hydraulic pressure is supplied to the pressure receiving chamber, and at the same time, the remaining hydraulic pressure on the pressure receiving chamber side is released, returning the displaced sleeve 69 to its original position. Then, this returning output is used as a steering reaction force to always return the ring gear 29 to its original state (orientation). Further, when control pressure is applied from the plugs 54 and 56 to displace the spool 53, the sleeve 69 is moved from the spool 53.
3 and rotates the lever 60. The ring gear 29 is rotated to the additional turning side by the displacement transmitted to the lever 60 (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 90 is provided on the cross member 83 so as to connect the left and right pivot shafts 89 and 89 of the rear wheel suspension. That is, the rear power cylinder 90 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 formed by a piston portion 95b having a diameter corresponding to 2a and 92b is slidably provided.

Also, piston rods 96a are attached to the piston ends on both sides.
, 96b are connected. And the piston part 9
A left chamber 97a and a right chamber 97b, which receive in-phase outputs, are formed in the large cross-sectional area of the cylinder chamber 91 divided by 5a. Also, the cylinder chamber 92 is lined up with the chambers 97a and 97b.
The phase output is received in a space where the cross-sectional area of a and 92b is small. This cylinder 94 is fixed to the cross member 83 with its axial direction defined in the left-right direction. Then, the left piston rod 96a is connected to the left intermediate joint 3.
8, and the right piston rod 96b is connected to the pivot shaft 39 of the right intermediate joint 38.
The rear wheels 82a, 82b can be steered by moving the piston 95.

The left chamber 97a and the right chamber 97b of this rear power cylinder 90 are connected to an oil flow path 9 to a control valve 98 for the same phase.
9, and the cylinder chambers 92a and 92b of the rear power cylinder 90 are connected to the phase control valve 10.
0 via oil flow paths 101a and 101b.

A spool valve as shown in FIG. 6 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.

In addition, on both sides of the peripheral wall of the case 102 facing the spaces of the grooves 222 and 223, there are reservoir side ports 224a, 224b, pump side ports 2) symmetrically centered on the convex portion between the grooves.
25a, 225b are provided, and further groove portions 222.22 are provided.
At the center of the peripheral wall of the case 102 facing the space No. 3, actuator side boats 226 and 227 are provided, respectively. The case 102 has a structure in which pilot ports 228 and 229 are provided at both ends of the spool for applying control pressure to the ends of the spool. The actuator side ports 226 and 227 are connected to the oil flow path 99.

The pilot boats 22g and 229 of this in-phase control valve 98 are connected to each left chamber 18. of the power steering 6, respectively. When the right chamber 19 is connected via the oil flow path 103 and power steering pressure is generated, the spool 2 in the neutral state
21 is displaced to switch between the reserve side ports 224a, 224b and the pump side ports 225a, 225b. An oil pump 105 is connected to each pump side port 225a, 225b of the control valve 100, which is driven by the differential gear 104 and generates oil pressure according to the vehicle speed (vehicle speed is high: oil pressure is increased). This makes it possible to supply t hydraulic pressure to the left chamber 97a or right chamber 97b of the rear power cylinder 90 in the steering direction, depending on the vehicle speed and the amount of movement of the spool 221. 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-boat throttle switching valve. A schematic structure of this switching valve is shown in FIG.

To explain the switching valve, 107 is a cylindrical case having 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 ports 108, 109. These ports 108 and 109 are connected to the oil flow path 10 through a branch path 132.
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 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. 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 port 126
．． 127 is the oil flow path 101a.

101b. Further, the chamber 122 is the passage space 12
An oil supply port 12 provided in the 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 m-type (constant discharge flow rate) oil pump 131 that is driven by the engine 20 together with the oil pump 13 .

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 port 4, port 1 for the reservoir is drilled on the outer periphery of the case.
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 118 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 118.
It is designed to allow access to 18 people.

In addition, each communication passage 138, 139 has a check valve 14 for regulating the flow toward the reservoir tank 106.
0 is set. Furthermore, a variable orifice 141 (or a variable choke) is provided between the communication passage between the check valve 140 and the reservoir boat 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 via a flow path 144 to a vehicle speed sensitive pressure generator 143 built into the differential-driven oil pump 105, and the pilot pressure generated from the vehicle speed sensitive pressure generator 143 is used to control the variable orifice 141. The amount of aperture can be varied in response to vehicle speed.

As a result, the control valve 100 determines the rate of change in the pilot pressure of the power steering 6 as the steering wheel 17 is turned based on the displacement of the spool 110 due to the pilot pressure applied to the spool end and the relative displacement of the sleeve 114 with respect to the spool 110. It is now possible to generate hydraulic pressure for the phase according to the vehicle speed (high vehicle speed: low oil pressure). That is, the control valve 100
is capable of supplying an output for steering the rear wheels 82a, 82b in the opposite direction to the front wheels 1a, lb to the cylinder chamber 92a or cylinder chamber 92b of the rear power cylinder 90 at the start of a steering operation.

The oil flow paths 1o1a 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 opening mechanism 14, so that the front wheels 1a and 1b can be advanced to the additional cutting side at the same time as the rear wheels 82a and 82b are in phase.

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, 1b and the rear wheels 82
a and 82b face the straight direction.

When the steering wheel 17 is turned, for example, to the right (at medium to high speeds) in order to turn from such a straight-ahead state (turn-in), the fluctuation rate of the power steering pressure and the vehicle speed Accordingly, - the instantaneous wheels 82a, 82b are in reverse phase, and - the instantaneous wheels 1a, lb
The steering angle increases 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.

Also, the ring gear 29 of the second stage planetary gear mechanism 22 tries to rotate due to the steering force, but the ring gear 29 is constantly affected by the force generated by the control valve 23 that tries to return the ring gear 29 to its original position. The hydraulic pressure generated by the 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 a steering reaction force, so the rotation of the planetary gear 31 continues as it is to the sun gear 28.
From there, it is transmitted to the valve input shaft 7a and the torsion bar 8. That is, when the ring gear 29 rotates in response to the steering force, the lever 60 is rotated by the plate 64.
It rotates in the same direction as the ring gear 29 using the groove 65 as a fulcrum. At this time, the sleeve 69 is also moved by the movement of the lever 60. In other words, a relative error occurs between the sleeve 69 and the spool 53. Then, hydraulic pressure is generated within the control valve 23 due to this relative displacement. This hydraulic pressure causes the sleeve 69.
Lever 60. A force is generated to return the ring gear 29 to its original position, that is, a position where the relative displacement with respect to the spool 53 is zero, and this force acts as a steering reaction force. Specifically, when the ring gear 29 receives the steering force and tries to turn counterclockwise,
The lever 60 rotates in the same direction about the groove 65 as a fulcrum. As a result, the sleeve 69 slides toward the plug 54 side, and a relative displacement occurs between it and the spool 53. Then, the flow rate from the oil pump 13 reaches the chamber 7.
1, and hydraulic pressure is generated in the chamber 71 due to the throttling effect of the chamber 71.

Then, this hydraulic pressure flows into the pressure receiving chamber 77 through the passage 76 and moves the sleeve 69 to the right.

This acts as a force to hold it in its original position.

The rotation transmitted to the torsion bar 8 is then 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 to assist the steering of the steering wheel 17.

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 stroke of this spool controls the oil discharged from the oil pump 105. 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 boat 109, the spool 110 is displaced (xl) to the left 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.

1 life xl +r for al-Fl-.

In other words, Xi malaFl-f1/Kl It is expressed as However, a is the area of the spool end surface.

K is the spring constant of springs 115 and 116.

fl is the preload fa of the spring, and F+ 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・Qb2/2ΦCd-d2 where δ is the fluid density, Qb is the flow rate flowing through the constriction, d is the cross-sectional area of the constriction, and Cd is the flow coefficient.

In addition, in the case of a choke structure, ΔP-8·π write μ·i/d2. However, ① 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. The relative displacement y at this time 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 r of the springs 112 and 113, and f2 is the preload value of the springs.

Since a constant flow of oil generated by the oil pump 131 is supplied from the oil supply port 129, a pressure difference proportional to the relative displacement y is generated from the actuator ports 126 and 127.

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

Therefore, the output oil pressure decreases from the actuator ports 126 and 127 in accordance with the vehicle speed, and a controlled oil pressure (differential pressure) is outputted in accordance with the rate of change in the power steering pressure.

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 to the plug 54 of the variable steering gear ratio device 14 as an output that increases the steering angles of the front wheels la, lb.

Then, the output of the cylinder chamber 92b, which attempts to steer the rear wheels 82a, 82b in the opposite direction to the front wheels, and the rear wheels 82a,
The rear wheels 82a and 82b are steered in accordance with the opposite-phase steering angle obtained by combining the output with the output of the left ventricle 97a which attempts to steer the rear wheels 82b in the same direction as the rear wheels.

Further, in the steering gear ratio variable device 14, the plug 54
When control pressure is applied to spool 5, the spool 5
3 slides to the right. Then, a relative displacement occurs between the spool 53 and the sleeve 69, and the flow rate from the oil pump 13 flows into the chamber 71. As a result, oil pressure is generated by the throttling effect of this chamber 71, and this oil pressure is guided to the pressure receiving chamber 77 through the passage 76. Therefore, 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. And 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 gears 27 and 31 are 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. is turned clockwise (phase advance control).

However, the front wheel steering angle can be controlled by a composite value of two inputs: the driver input from the steering wheel 17 and the oil pressure input from the plug 54.66.

Therefore, variable gear ratio control can be performed simply by applying control pressure to the plugs 54 and 56, and the control is simpler than electronic control. In other words, phase advance control can be performed with simple control. Furthermore, since the gear ratio is varied using fluid pressure, reliability against noise, radio interference, etc. is high.

Further, since the set screw and the stopper portion 14a prevent more input than necessary from entering the planetary gear mechanism 21.22, the planetary gear mechanism 21.22 can be made smaller and lighter. That is, when the steering wheel 17 is steered more strongly at the full steering angle of the steering wheel 17, the pin component 50 and the recess 47 become disengaged due to displacement of the spring 49 in the compression direction. Subsequently, the projecting pieces 24a, 24a at the end of the input shaft are connected to the valve input shaft 7.
a, and the steering force from the steering wheel 17 is directly applied to the valve input shaft 7a.
will be communicated to.

This eliminates the need for the planetary gear mechanism 21.22 to withstand more than necessary steering force, and the planetary gear mechanism 21.
22 parts are small and lightweight.

However, when the rate of change in the power steering pressure disappears, only the output from the in-phase control valve 98 according to the vehicle speed remains, and the original steady state four-wheel simultaneous steering (normal in-phase four-wheel steering) is restored.
).

In one embodiment, the rate of change in the power steering pressure of the front wheels 1a, lb is used as the control pressure, but a pressure output means constituted by a hydraulic circuit with the steering angular velocity as the control pressure may also be used. In this case as well, a control pressure incorporating a vehicle speed factor may be used.

Furthermore, in one embodiment, the present invention was applied to a variable steering gear ratio device using two sets of planetary gear mechanisms, but it may of course be applied to a variable steering gear ratio device having a -set of amm military aircraft +1. .

(Effects of the Invention) As described above, according to the present invention, the gear ratio can be varied by controlling by applying control pressure to the control pressure boat, and the control is simpler than electronic control.

Furthermore, since the gear ratio is varied using fluid pressure, reliability against noise, radio interference, etc. is high.

[Brief explanation of drawings]

FIGS. 1 to 7 show one embodiment of the present invention.
2 is a partially sectional perspective view showing the variable steering gear ratio device of the present invention, FIG. 2 is a sectional view showing the two sets of planetary gear mechanisms, and FIG. 3 is a sectional view showing the structure of the ring gear displacement mechanism. Figure 4 is a sectional view taken along line A-A in Figure 2, Figure 5 is a configuration diagram showing a four-wheel steering system to which a variable steering gear ratio device is applied, and Figure 6 is a control valve for the same phase. 7 is a sectional view showing a phase control valve. 7a... Valve input shaft (output shaft)
, 14... Steering gear ratio variable device, 21°22
...Planetary gear mechanism, 23...Control valve (
ring gear displacement mechanism), 24... input shaft (input shaft), 54a, 56a... plug hole (control pressure boat), 60... lever transmission member, 71
~, 76.78... Chamber 1 passage (opening/closing passage), 77.7
9...Pressure receiving chamber, 80...Boat (fluid inlet boat))
, 81...boat (fluid outlet boat). Applicant's agent Patent attorney Takehiko Suzue Bufu Tank Oil 1r1#nfu' Figure 6

Claims (1)

[Claims] In a variable steering gear ratio device, a planetary gear mechanism is provided between an input shaft and an output shaft, and a ring gear displacement mechanism for displacing the ring gear in a rotational direction is provided in the planetary gear mechanism, the ring gear displacement mechanism comprising: a valve body, a spool slidably provided within the valve body, a sleeve slidably provided around the spool, a fluid inlet port and a fluid outlet port for steering reaction force provided in the valve body; a pair of pressure receiving chambers provided on the end face side of the sleeve and facing the end of the sleeve; and a pair of pressure receiving chambers provided on the spool and the fluid inlet port and the fluid outlet port provided in the spool and configured to receive pressures according to relative displacement of the spool and the sleeve. an opening/closing passage that controls flow between the valve body and the spool and positions the sleeve relative to the spool; a transmission member provided in the valve body that transmits the displacement of the sleeve to the ring gear of the planetary gear mechanism; A variable steering gear ratio device comprising a pair of control pressure ports for inputting control pressure for ring gear displacement at one end thereof.