JPH01103575A - Four-wheel steering gear - Google Patents

Abstract

PURPOSE:To make a steering mode continuously transferrable to both inphase and antiphase modes by linking a tip of a worm shaft with a reduction gear mechanism, while connecting this reduction gear mechanism to an inner rotor of a trochoidal gear mechanism via a transmission shaft installed in the reduction gear mechanism. CONSTITUTION:When an inner rotor 43 of a trochoidal gear mechanism (g) is rotated, a connecting portion of a connecting rod 43 connected to this rotor is moved forward. When a steering angle of a handwheel is small, a turning angle of the rotor also becomes smaller. When the turning angle of the rotor 43 is small like this, displacement of the connecting portion of the rod 51 is going to grow larger in a positive direction, by way of example. When the steering angle of the handwheel becomes larger, however, the turning angle of the rotor 43 also becomes larger, and at this time a displacing direction of the connecting portion of the rod 51 is reversed, so that the displacement increases in a negative direction on and after the specified time. Since a variation in the moving direction of this rod 51 is turned to a variation in the changeover direction of a spool 52 for a rear-wheel control valve VR, a steering mode is automatically transferred.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel steering device that switches one front and rear wheel in an in-phase mode or in an opposite-phase mode depending on the steering angle of a steering wheel.

(Prior Art) As a four-wheel steering device for steering the front and rear wheels, for example, a device described in Japanese Patent Application Laid-Open No. 61-211168 has been known. It has been clarified as.

In the conventional device shown in FIGS. 8 and 9, when the handle l is turned, the input shaft 2 connected thereto also rotates. A pinion 3 is formed at the tip of the input shaft 2, and the pinion 3 is connected to the rack. It is engaged with 4. This rack 4 is linked to the piston loft of the front wheel power cylinder 5, and therefore, when the front wheel power cylinder 5 operates, this rack 4
The front wheels 6 are also moved and the front wheels 6 are steered.

The input shaft 2 configured as described above is movable in the horizontal direction, and has a front wheel control valve 7 and a rear wheel control valve 8.
The rocking lever 9 and IO are skewered. The swing levers 9 and IO have one end as a fulcrum 11.12, and the other end as the spool of the control valve 7, 8.
It is inserted into 14.

However, when the input shaft 2 is rotated by turning the handle l as described above, the nion 3 formed on the input shaft 2 also rotates, but the rack 4 does not move due to the action of the switching resistance at this time. , Pinion 3 will be transferred.

When the pinion 3 rolls on the rack 4, the input shaft 2 swings, causing the swing lever 9.10 to swing. Therefore, the spools 13 of the front wheel control valve 7 and the rear wheel control valve 8.
14 is switched to the swinging direction of the swinging levers 9 and 10.

When the spool 13 of the front wheel control valve 7 is switched, the fluid discharged from the front wheel pump Pl is supplied to one chamber of the front wheel power cylinder 5, and the fluid in the other chamber is flowed into the tank T, thereby controlling the front wheel. The power cylinder 5 operates to steer the front wheels 6 in a predetermined direction.

Also, the rear wheel control valve 8 communicates with the rear wheel cylinder 17.18 via a passage 15.16, or when the spool 14 moves in a predetermined direction as described above, the rear wheel control valve 8 is connected to the rear wheel cylinder 17.18 through a passage 15.16. The fluid discharged from the rear wheel pump P2 is supplied to the wheel cylinder 17 or 18 and expands, and the fluid from the other rear wheel cylinder 18 or 17 is returned to the tank T and contracts.

When the cylinders 17 and 18 for both rear wheels extend and contract, rotational force acts on the suspension member 19, so that the suspension member 19 rotates while compressing the mount bushing 20 or 21. When the suspension member 19 rotates as described above, the rear wheels 22 are steered accordingly.

(Problems to be Solved by the Invention) In the conventional device as described above, the swing levers 9 and 10 of the front wheel control valve 7 and the rear wheel control valve 8 are as follows.

Since the input shaft 2 of - is skewered, the re-control valve 7.
The switching direction of the spools 13 and 14 of 8 is always the same.

Therefore, in this state, the steering mode of the front and rear wheels cannot be set in the same phase or out of phase depending on the steering angle of the steering wheel, that is, the steering mode cannot be continuously switched depending on the driving conditions or the like.

Therefore, in order to continuously switch the steering mode, between the rear wheel control valve 8 and the rear wheel cylinders 17 and 18,
Although it is conceivable to provide a solenoid valve or the like, there is also the problem that it is difficult to maintain sufficient switching accuracy when considering the responsiveness of the solenoid valve.

The purpose of this invention is to maintain sufficient accuracy.

An object of the present invention is to provide a device in which a steering mode can be continuously switched between an in-phase mode and an anti-phase mode.

(Means for Solving the Problems) The present invention includes: an input shaft linked to a handle; an ohmic shaft connected to the input shaft via a torsion bar; a rotary valve that switches according to rotation of the input shaft; It operates in response to the switching of the rotary valve, and includes a piston fitted to the ohmic shaft and a sector gear that meshes with the gear formed on the piston. The system is based on a four-wheel steering system that operates the system.

Based on the above device, the present invention links the tip of the ohmic shaft to a reduction mechanism, and connects this reduction mechanism and the inner rotor of the trochoid gear mechanism.
The trochoid gear mechanism is connected via a transmission shaft provided in the reduction mechanism, and the outer rotor of the trochoid gear mechanism is fixed, and an output shaft is fixed to the inner rotor. Alternatively, a connecting rod connected to the spool of the rear wheel control valve is connected to a position corresponding to the vicinity of this center, and the connecting rod is connected to a position corresponding to the vicinity of the center, and the connecting rod is connected to a position corresponding to the vicinity of the center, and the connecting rod is connected to a position corresponding to the vicinity of the center. The present invention is characterized in that the rear wheel control valve is configured to be switched.

(Operation of the present invention) Since the present invention is configured as described above, when the inner rotor of the trochoid gear mechanism rotates, the connecting portion of the connecting rod connected to the inner rotor moves. When the steering angle of the steering wheel is small, the rotation angle of the inner rotor is also small. In this way, when the rotation angle of the inner rotor is small, the displacement of the connecting portion of the connecting rod increases by 1, for example, in the positive direction. The rotation angle also increases.

When the rotation angle of the inner rotor is large, the direction of displacement of the connecting portion of the connecting rod is reversed, and the amount of displacement increases in the negative direction from a predetermined point of time.

Therefore, the connecting rod connected to the inner rotor moves in different directions when the displacement amount is increasing in the positive direction and when it is increasing in the negative direction.

In this way, the change in the direction of movement of the connecting rod is
This appears as a change in the switching direction of the spool of the rear wheel control valve. If the switching direction of the spool of the rear wheel control valve changes, the direction of supply of pressure fluid to the rear wheel cylinder also changes, thereby automatically switching the steering mode.

(Effects of the Present Invention) According to the four-wheel steering device of the present invention, the switching direction of the rear wheel control valve can be controlled according to the steering angle of the steering wheel, so in the medium and high speed range where the steering angle is small, the front and rear wheels are By steering the vehicle in the same phase mode, it is possible to maintain its steering stability and improve the ability to turn around in a low speed range where the steering angle is large.

Moreover, since such switching of the steering mode can be performed automatically according to the steering angle, the accuracy can be maintained sufficiently.

(Embodiment of the present invention) The embodiment of the present invention shown in FIGS.
A valve case 24 is provided at one end of the input shaft 3, and a rotary valve 26 that is switched in relation to the rotation of the input shaft 25 is housed in the valve case 24. and,
The input shaft 25 has one end connected to the handle 27, and the other end connected to the worm shaft z9 via a torsion bar 28.

A piston 30 is slidably housed in the gear case 23, and pressure chambers 31 and 32 are defined within the two cases, and the ohmic shaft 29 is passed through the center of the piston 30. There is. Further, these pistons 30 and the ohmic shaft 29 are ohmically connected, so that when the ohmic shaft 29 rotates, the piston 30 moves, and when the piston 30 moves, the ohmic shaft 29 rotates. The piston 30 thus configured has a gear 33.
A sector gear 34 is meshed with this gear 33. The sector gear 34 meshed with the gear 33 rotates as the piston 30 reciprocates, and in conjunction with the rotation, rotates a pitman arm (not shown) to steer the front wheels.

The rotary valve 26, the ohmic shaft 29, the piston 30, etc. constitute the main elements of the front wheel steering device.

Gear case 2 provided on the opposite side of the valve case 24
A control case 35 is provided on the outside of the gear case 3, and the tip of the ohmic shaft 29 projects into the gear case 23. A pinion 36 is integrally formed on the protruding end of this ohmic shaft 29.
is engaged with an internal gear 37 rotatably provided on the inner periphery of the control case 35. And the internal gear 37
An output shaft 38 that rotates integrally with the output shaft 38 is connected to the output shaft 38, and one end of a transmission shaft 39 is connected to the output shaft 38. The transmission shaft 39 has a gear 40 formed at its tip, is swingable around a pin 41 at a connecting portion with the output shaft 38, and is configured to rotate integrally with the output shaft 38.

Note that the pinion 36. The internal gear 37, the output shaft 8, and the transmission shaft 39 constitute the speed reduction mechanism r of the present invention.

The transmission shaft 39 configured as described above has a trochoid gear mechanism g
This trochoid gear mechanism g has an outer rotor 42 and an inner rotor 43 as main elements. In other words, the outer rotor 42 has bolts 44
is fixed to the control case 5, and a rotor 46 is fitted into a recess 45 formed on the inner periphery thereof. Further, the inner rotor 43 has tooth grooves 47 formed on its outer periphery, and the radius of curvature of the ri1 groove 4 groove upper 7 outer rotor 42 and the rotor 46 are made equal. The number of tooth grooves 47 on the inner rotor 43 is smaller than the number of rotors 46 on the outer rotor 42, and when the four inner rotors are engaged with the outer rotor 42, as shown in FIG. 4 is outer rotor 4
It is made to be eccentric with respect to 2.

The four inner rotors configured as described above have an internal gear 48 formed in the center thereof, and the gear 40 of the transmission shaft 39 is meshed with the internal gear 48. A connecting plate 49 is fixed to the outside of this inner rotor 43, and the base end of a connecting rod 51 is connected to the outside of this connecting plate 49 via a spherical bearing 50.

The tip of the connecting rod 51 is connected to a spool 52 of the rear wheel control valve vlI, and the spool 52 is slidably housed in a valve sleeve 53.

Further, this valve sleeve 53 is connected to the control case 35.
The valve hole 54 is slidably installed inside the valve hole 54 formed in the valve hole 54 formed in the valve hole 54 .

A servo cylinder C provided in the control case 35
A piston 56 is installed inside the cylinder portion 55 of the cylinder. The piston 56 thus configured is provided with piston rods 5 and 58 on both sides, and one piston rod 57 is made to protrude toward the valve hole 54 side, and its protruding end is connected to one end of the valve sleeve 5. It is in contact with the

As is clear from FIG. 3, a supply groove 59 extending in the axial direction is formed on the outer periphery of the valve sleeve 53, which constitutes the main element of the rear wheel control valve vIl. This supply yI59 is supplied to the rear wheel pump P via a pump port 60 formed in the control case 35.

The first .
2-ring v! It is also connected to I61.62. moreover,
A tank boat 63 is provided on the outer periphery of the valve sleeve 53.
A tank passage 64 is formed which is always in communication with the tank. This tank passage 64 communicates with a third annular groove 65 formed between the first and second annular grooves 61 and 62.

Further, the spool 52, which also constitutes the main element of the rear wheel control valve VR, is formed with a 1.2 annular surrounding portion 66, 67; When in the neutral position shown, it communicates with outflow boats 68,69. This one outflow boat 68 is connected to the passage 70
One cylinder chamber 72 of the rear wheel cylinder 71 via
The other outflow boat 69 communicates with one pressure chamber 74 of the servo cylinder C via a communication path 73. The pressure chamber 7 on the opposite side to this one pressure chamber 74
5 communicates with the other cylinder chamber 77 of the rear wheel cylinder 71 via one passage 76.

Reference numerals 78 and 79 in FIG. 1 indicate operating check valves provided in the first passage 70 and 76.

When the handle 27 is rotated, the input shaft 25 rotates accordingly, but since the switching resistance at this time acts on the sector gear 34, the ohm shaft 29 does not rotate. Torsion bar 28
The rotary valve 26 is switched by twisting the handle, but for example, if the handle is turned to the left,
The rotary valve 26 is switched to the right position in FIG.

When the rotary valve switches to the right position in this way,
The discharge fluid of the front wheel pump P passes through one passage 80,
It is supplied to a pressure chamber 31 defined by a piston 30. Then, the fluid in the other pressure chamber 32 is returned to the tank T via the passage 81, and the piston 30 moves to the right in FIG. Turn to. Further, when the piston 30 moves in this manner, the ohmic shaft 29 also rotates, and the rotational force thereof is transmitted to the internal gear 37 via the pinion 36, causing the internal gear 37 to rotate.

In this way, the rotational force of the ohmic shaft 29 is decelerated in the process of being transmitted to the internal gear 37, and the internal gear 37
The rotational force is transmitted to the inner rotor 43 of the trochoid gear mechanism g via the transmission shaft 39.

When the rotational force is transmitted to the inner rotor 43, the inner rotor 43 either revolves while rotating, or, for example, if the inner rotor rotates to the left in the direction of arrow 82 in FIG. 4, the direction of revolution is on the opposite side. The direction is to the right. Therefore, the central portion at this time is 0. The movement trajectory of is as follows.

That is, the vertical axis shown in FIG. 4 is Y, the horizontal axis is X, and the center of the inner rotor when the handle is held at the neutral position is 0. but.

e in the -Y direction with respect to the center 0° of the outer rotor 42.
Assuming that the center O1 is eccentric by 1, the locus of movement of the center O1 will be as shown by curve a in FIG. That is, during the initial rotation of the ohmic shaft 29, in other words, when the rotation angle is small, the center 0. shifts in the negative direction of the X axis,
When the rotation angle increases and the movement locus exceeds the X-axis, the direction of transition with respect to the X-axis is reversed to the positive direction. Furthermore, when the rotation angle of the ohm shaft 29 increases,
The center is 0. moves beyond the Y-axis in the positive direction of the X-axis.

Since the connecting rod 51 is connected to the center 0° of this inner rotor 43 via the spherical bearing 50, the center 0°. The movement of in the X-axis direction is
This reciprocating motion of the connecting rod is converted and transmitted to the spool 52 of the rear wheel control valve vll.

Therefore, as described above, depending on the steering angle of the handle 27, the spool 52 is switched in the positive direction of the X-axis or in the negative direction.

When the handle is slightly turned to the left, the connecting rod 51 is pulled upward in FIG. 2, the spool 52 is also moved upward, and the rear wheel control valve vll is switched to the left position in FIG. . Rear wheel control valve V
When ll is switched to the above left position, the rear wheel pump P2
The discharge fluid flows through the passageway 70 and the operating check valve 78.
One cylinder chamber 72 of the rear wheel cylinder 71 via
The piston 83 of the cylinder 71 is moved to the right in Figure 1, and the rear wheels (not shown in Figure 1) are steered in the same direction as the front wheels. At this time, rear wheel cylinder 7I
The fluid in the other cylinder chamber 77 is supplied to the other pressure chamber 75 of the servo cylinder C via the operating check valve 79 and the passage 76. Further, the fluid in one pressure chamber 74 of this servo cylinder C is returned to the tank T via the passage 7 and the rear wheel control valve vlI. Therefore, the piston 56 of this servo cylinder C moves upward in FIG. 2 and pushes the sleeve 53 upward in FIG. , the piston 56 stops.

When the relative relationship between the sleeve and the spool returns to the above-mentioned neutral state, the fluid discharged from the rear wheel pump P2 is returned to the tank T, so that no pressure fluid is supplied to the rear wheel cylinder, and the rear wheel pump P2 is returned to the tank T. The cylinder is operated check valve 78
．． The movement position is maintained by the action of 79.

That is, when the rotation angle of the steering wheel is small as described above, the switching direction of the rear wheel control valve becomes the in-phase mode, and the front and rear wheels are steered in the same direction.

Then, when the handle is further rotated from the above state and the rotation angle is increased, the center 0 of the inner rotor 43 of the trochoid gear mechanism g. The direction of transition of is reversed, and
Shift in the positive direction of the axis. Therefore, at this time, the connecting rod 5] is lowered, the spool 52 is moved downward, and the rear wheel control valve vll is switched to the right position in FIG.

When the rear wheel control valve is switched to the right side position in this manner, the discharge fluid of the rear wheel pump P2 is supplied to one pressure chamber 74 of the servo cylinder C via one passage 7. At this time, the fluid in the other pressure chamber 75 is pushed out to the passage 76 side and is supplied to the other cylinder chamber 77 of the rear wheel cylinder 71 via the operating check valve 79. Further, the fluid in one cylinder chamber 72 is supplied to the operating check valve 78, the passage 70, and the rear wheel control valve v9.
Since the piston 83 of the rear wheel cylinder moves to the left in FIG. ff11, the rear wheel is steered to the right.

In addition, as mentioned above, one pressure chamber 7 of the servo cylinder C
When pressure fluid is supplied to 4 and the piston 56 moves,
Since the sleeve 53 also moves with the movement, the piston 56 stops at a position where the relative relationship between the sleeve and the spool is in the neutral state shown in the figure.

In addition, so far we have explained the case where the handlebar is rotated to the left, but if the handlebar is rotated to the right, the switching direction of the rear wheel control valve vll will simply be reversed; This is the same as the case above.

Therefore, according to this embodiment, when the rotation angle of the steering wheel is small, that is, when driving at medium to high speeds without turning the steering wheel significantly, the front and rear wheels can be steered in the same direction to improve steering stability. Ru. On the other hand, when driving at low speeds by turning the steering wheel sharply, the front and rear wheels are steered in the opposite direction.
It is possible to maintain that maneuverability.

By changing the connection position of the connecting rod 51 with respect to the inner rotor 43, the movement locus drawn by the connection portion can be changed, and the curve shown in FIG. 5 shows this situation. , c. In other words, one curve C is the movement locus when the connecting rod 51 is connected to the P4 position shown in FIG. This is the locus of movement when the connecting rod 51 is connected to the position and eccentric by a distance e. Therefore, the connection position of the connecting rod 51 to the inner rotor 43 is determined by considering the characteristics of the vehicle, etc. W! ! This allows you to select your preferred steering characteristics.

Furthermore, Fig. 6 is a graph showing the relationship between the displacement amount of the rear wheel control valve vlI and the steering angle of the steering wheel, and Fig. 7 is a graph showing the relationship between the steering angle of the steering wheel and the turning angle of the rear wheels. It is a graph.

[Brief explanation of the drawing]

Drawings 1 to 7 show embodiments of this invention.
The figure is a circuit diagram, Figure 2 is a sectional view of the main parts of the device, Figure 3 is a diagram of the internal gear of the reduction mechanism as seen from inside, Figure 4 is a side view of the trochoid gear mechanism, and Figure 5 is a side view of the trochoid gear mechanism. The figure shows the movement locus of the connection part of the connecting rod with respect to the inner rotor, Figure 6 is a graph showing the relationship between the displacement of the rear wheel control valve vll and the steering angle of the steering wheel, and Figure 7 is the steering angle of the steering wheel. A graph showing the relationship between and the steering angle of the rear wheels.
8.9 shows a conventional device, FIG. 8 is a mechanical diagram, and FIG. 9 is a sectional view of the main part. 25...Input shaft, 26...Rotary valve, 27-
...Handle, 28...Toshimin bar, 29-...
Worm shaft, 30... Piston, 33... Gear, 3
4... Sector gear, 38... Output shaft, 3g... Transmission shaft, "... Reduction mechanism, g... Trochoid gear 4j
14IIi, 42...outer rotor, 43...
Inner rotor, 51... connecting rod, v
R...Rear wheel control valve, 52...Spool.

Claims (1)

[Claims] An input shaft connected to the handle, a worm shaft connected to the input shaft via a torsion bar, a rotary valve that switches according to the rotation of the input shaft, and operates according to the switching of the rotary valve, and A four-wheel steering device comprising a piston fitted to a worm shaft and a sector gear meshing with a gear formed on the piston, the four-wheel steering device operating a rear wheel steering mechanism in conjunction with the steering wheel operation, wherein the tip of the worm shaft is linked to the reduction mechanism, and the reduction mechanism and the inner rotor of the trochoid gear mechanism are connected via a transmission shaft provided in the reduction mechanism, and the outer rotor of the trochoid gear mechanism is fixed, and the An output shaft is fixed to the inner rotor, and a connecting rod linked to a spool of a rear wheel control valve is connected to the output shaft at a position corresponding to the center of the inner rotor or near the center,
A four-wheel steering device configured to switch the rear wheel control valve according to a movement locus of a connection point of a connecting rod that moves with rotation of the inner rotor.