JPS63203478A - Four-wheel steering device for vehicle and method for assembling it - Google Patents

Abstract

PURPOSE:To improve the assembly workability by performing the toe adjustment with a rear wheel steering mechanism adequately held, connecting the front wheel and rear wheel steering mechanisms, then releasing a lock. CONSTITUTION:A rear wheel steering rod 9 is located at the neutral position, a displacement means C is set to the hydraulic drive means standard state, then an input shaft 14 is locked by a lock means E, the toe adjustment is performed on rear wheels 7L, 7R, the input shaft 14 is connected to a shaft 19, and a lock is released by the lock means E. Accordingly, a rear wheel steering mechanism B can be held at a proper state by the lock means E having a lock bolt 101, thus the rear wheels 7L, 7R can be steered in response to the steering of front wheels 1L, 1R after the rear wheel steering mechanism B is connected to a front wheel steering mechanism A.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel steering system for an automobile that controls the steering of the rear wheels in accordance with the steering of the front wheels, and a method of assembling the same. be.

(Prior Art) Conventionally, as a four-wheel steering system for this type of automobile, a front wheel steering mechanism for steering the front wheels and a front wheel steering mechanism for steering the rear wheels have been used, for example, as disclosed in Japanese Unexamined Patent Publication No. 58-122259. The front and rear wheel steering mechanisms are mechanically connected by a shaft extending in the front-rear direction to transmit the amount of rotation of the front wheels to the rear wheel steering mechanism, thereby steering the front wheels. It is known that the rear wheels are steered at a predetermined steering ratio depending on the situation.

In the above-mentioned four-wheel steering system, the rear wheel steering rod, the hydraulic drive means, and the displacement amount control means are connected to the rear wheel steering mechanism as a specific means for steering the rear wheels in accordance with the steering of the front wheels. It is provided as a component. That is, the rear wheel steering rod is a member that extends in the vehicle width direction, has both ends connected to rear wheel support members, is biased to a predetermined neutral position in the vehicle width direction, and is movable in the vehicle width direction. , the rear wheels are steered by this displacement of the rear wheel steering rod. Further, the hydraulic drive means applies hydraulic pressure to the rear wheel steering rod to displace the rear wheel steering rod from the neutral position in the vehicle width direction, and the displacement amount control means further includes a hydraulic drive means and a shaft. The drive of the hydraulic drive means is controlled in accordance with the steering M of the front wheels transmitted by the shaft connected to the hydraulic drive means.

In order for the rear wheel steering mechanism that includes these components to function properly, when assembling the four-wheel steering system, the rear wheel steering rod must be positioned at the neutral position, and the displacement amount control means must be placed in the neutral position. Hydraulic drive means control 1 corresponding to the neutral position of the steering rod! It is important to connect the front wheel steering mechanism and the rear wheel steering mechanism (that is, connect the shaft and the displacement amount control means) in the state set to the 4-quadrant state.

(Problem to be Solved by the Invention) However, after the rear wheel steering rod is positioned at the neutral position and the displacement amount control means is set to the hydraulic drive means control reference state, the shift and displacement are immediately performed. No connection with quantity control means is possible. That is, it is necessary to perform toe adjustment of the rear wheels during this time. For this reason, even if the above operation is performed, the displacement amount control means may deviate from the above reference state while the rear wheel toe is being adjusted. If a connection is made with the means, the steering of the rear wheels will be performed with characteristics offset from the desired characteristics with respect to the steering of the front wheels, which is undesirable.

In addition, when the shaft and the displacement amount control means are connected in such an offset state, for example,
67279jl, it is possible to correct the offset using this adjusting means, but there is a limit to the amount of offset that can be corrected, and Since it is a measure, it is difficult to limit the amount of correction, and the workability of dark blue is also not good.

The present invention has been made in view of the above circumstances, and has good assembly workability, and after the assembly is completed, the rear wheels can be steered according to the desired characteristics in accordance with the steering of the front wheels. The present invention aims to provide a four-wheel steering system for an automobile and a method for assembling the same.

(Means for Solving the Problems) The four-wheel steering system for an automobile according to the present invention is provided with a locking means for locking the position change control means to stop its operation, thereby positioning the rear wheel steering rod at the neutral position. In addition, the rear wheel steering mechanism can be temporarily held in a state in which the position change control means is set to the hydraulic drive means 1III reference state. In this system, the toe adjustment of the rear wheels is performed with the rear wheel steering mechanism held as described above, and then the front wheel steering mechanism and the rear wheel steering IIM4 are connected, and then the lock is released. , This aims to achieve the ``-2'' purpose. That is, the four-wheel steering device for an automobile according to the present invention includes a front wheel steering mechanism that steers the front wheels in response to steering wheel steering, and a rear wheel steering mechanism that steers the rear wheels in response to the steering of the front wheels by the front wheel steering mechanism. a rudder mechanism;
A four-wheel steering device for an automobile, comprising a shaft connected to the front wheel steering mechanism and the rear wheel steering mechanism, and transmitting the amount of steering of the front wheels by the front wheel steering mechanism to the rear wheel steering mechanism. The rear wheel steering mechanism extends in the vehicle width direction, has both ends connected to rear wheel support members, and is biased to a predetermined neutral position in the vehicle width direction, and is movable in the vehicle width direction. a rod, a hydraulic drive means for displacing the rear wheel steering rod from the neutral position in the vehicle width direction by applying hydraulic pressure to the rear wheel steering rod, and a hydraulic drive means connected to the hydraulic drive means and the shaft for steering the front wheels. displacement amount control means for controlling the drive of the hydraulic drive means according to the If all amount, and operation of the displacement ffl control means by locking the displacement amount υ11111 means in the vicinity of a connecting portion of the displacement amount control means to the shaft. It is characterized by comprising a locking means for stopping the.

Further, a method for assembling a four-wheel steering device for a motor vehicle according to the present invention is an assembling method for assembling a four-wheel steering device for a motor vehicle having the above-mentioned configuration, and includes coupling the shaft and the displacement amount control means and the locking means. With the displacement ffiυ control means unlocked, the rear wheel steering rod is positioned at the neutral position, and the displacement amount control means is set to a hydraulic drive means control reference state corresponding to the neutral position of the rear wheel steering rod. The displacement control means is locked by the locking means, and in this state, the toe adjustment of the rear wheels is performed.Meanwhile, the toe adjustment of the front wheels is made once, and then the displacement amount control means and the shaft are locked. and then unlocking the displacement amount control means by the locking means.

The above-mentioned "predetermined neutral position" means the position of the rear wheel steering rod in the vehicle width direction which should serve as a reference when steering the rear wheels.

The above-mentioned "locking means" is not limited to a specific configuration as long as it can lock the displacement amount control means near the connection part to the shaft and stop its operation, for example, bolt tightening, positioning. It can be configured to be locked by inserting a bottle or the like. In addition, "near the connecting part of the displacement amount control means to the shaft" here means:
When the displacement control means is locked by the locking means, the displacement It! 1911 Means a part that can stop the operation of the means, and does not necessarily have to be a part close to the above-mentioned connecting part.

The above-mentioned "hydraulic drive means Ill m m semi-state" refers to the displacement jik III when the displacement m1ll means controls the drive of the hydraulic drive means according to the amount of steering of the front wheels.
This means a state that serves as a reference for control corresponding to the neutral position of the rear wheel steering rod of the In means.

The above-mentioned "front wheel toe adjustment" may be performed either before or after the rear wheel toe adjustment, as long as the shaft and the displacement control means are disconnected, and furthermore, before the rear wheel toe adjustment is performed. If this is to be carried out, it may be carried out either before or after the displacement control means is locked by the locking means.

(Function) With the above configuration, the rear wheels are kept in the appropriate state until the connection between the rear wheel steering mechanism and the front wheel steering mechanism is completed, that is, the rear wheels are rotated according to the desired characteristics in response to the steering of the front wheels. It becomes possible to maintain the state in which the vehicle is steered.

(gh song of invention) Therefore, according to the present invention, the troublesome work of correcting the offset of the steering characteristics of the rear wheels after connecting the front wheel steering mechanism and the rear wheel steering mechanism is unnecessary, and the assembly work It is possible to improve sexual performance.

(Examples) Examples of the present invention will be described in detail below with reference to the accompanying drawings.

First, the overall structure of an embodiment of a four-wheel steering system for an automobile according to the present invention will be schematically explained with reference to FIG.

In FIG. 1, the front wheel steering mechanism A for steering the left and right front wheels IL and IR consists of a steering wheel 2, a rack-and-nion machine 4M3 that converts the rotational motion of the wheel 2 into an RIIA reciprocating motion, It is comprised of a front wheel steering rod 4 provided with this mechanism 3, and left and right knuckle arms 6L and 6R connected to both left and right ends of this rod 4 via tie rods 5L and 5R, respectively.

On the other hand, a rear wheel steering mechanism B for steering the left and right rear wheels 7L and 7R is held in a cylindrical casing 8a that constitutes a part of the housing 8 so as to be slidable in the left-right direction (vehicle width direction). 11 A rear wheel steering rod 9 extending in the width direction, and a tie rod 1oL1 connected to both left and right ends of this rod 9, respectively.
1oR, and left and right knuckle arms 11L and 11R connected to these, respectively, and when the rear wheel steering rod 9 is displaced from the illustrated position (neutral position) to the vehicle width, the rear wheel 71 .7R is designed to be steered.

A precompressed return spring 42 is installed between the rear wheel steering rod 9 and the casing 8a, and the elastic force of the return spring 42 biases the rear wheel steering rod 9 to the neutral position. It has become. Further, the rear wheel steering rod 9 is integrally provided with a hydraulic drive means that applies hydraulic pressure to the rod 9 to displace the rod 9 from the neutral position in the vehicle width direction against the elastic force of the return spring 42. It is being

The hydraulic drive means includes a power cylinder 12, an oil passage (described later) for supplying hydraulic pressure to the power cylinder 12, and a spool valve 25 for switching this oil passage.

The power cylinder 12 has left and right hydraulic chambers 12a and 12b partitioned by a piston 13 fixed to the rear wheel steering rod 9 in a casing 8a, and both internal pressure chambers 1 are separated.
Oil is supplied and discharged to 2a and 12b.

C is a displacement control means for controlling the drive of the hydraulic drive means to displace the rear wheel steering rod 9 according to the steering angle of the front wheels IL and IR, A control rod 15 is provided.

Although the configuration of the displacement amount control means C will be described later, the linear reciprocating motion of the rod 4 in response to the operation of the steering wheel 2 is converted into rotational motion by the 12 rack and pinion mechanisms 16 provided on the front wheel steering rod 4. , this rotational motion is transmitted to the input shaft 14 of the displacement control means C via the universal joints 17, 18 and the shaft 19. That is, the steering M of the front wheels 11°1R by the front wheel steering mechanism is transmitted to the input shaft 14. On the other hand, the control rod 1 as the output shaft
5 is provided so as to move parallel to the rear wheel steering rod 9. Further, a pulse motor 21 for changing the steering ratio (rear wheel steering angle θR/front wheel steering angle θr) according to the vehicle speed is connected to this displacement control means C. With respect to the vehicle speed detected by the vehicle speed sensor 22,
The direction and amount of rotation thereof are controlled in accordance with the vehicle speed by the control circuit 23 which provides a corresponding output. Reference numeral 24 denotes a steering ratio sensor mounted above the housing 8, and the output of this sensor 24 is given to a control circuit 23 to feedback control the motor 21.

The displacement Mk III tl1 means is housed in a storage casing 8b integrally formed with a cylindrical casing 8a that houses the rear wheel steering rod 9, and the control rod 15
is connected to a spool pulp 25 of hydraulic drive means. This spool pulp 25 is slidably provided within a valve housing 27 that is fixed to the rear wheel steering rod 9 via a connecting portion 26 . Also this spool pulp 2
5 is a control rod 15 derived from the displacement amount control means C.
It is provided on an extension of the rear wheel steering rod 9, and is provided so as to be displaceable in parallel with the rear wheel steering rod 9, that is, in the vehicle width direction. and inside the valve housing 27 and the power cylinder 1.
In order to supply oil into the hydraulic chambers 12a and 12b of 2, the housing 8, the rear wheel steering rod 9 and the connecting portion 2
A plurality of oil passages are formed inside each of the oil passages 6 in a communication relationship as described below. That is, the oil in the oil tank 31 that is pumped by the oil pump 30 enters the oil path 33 in the housing 8 from the oil path 32a, and further passes through the rear wheel steering rod 9 that is slidably supported in the cylindrical casing 8a. The oil is supplied to an oil chamber 36 in the valve housing 27 through an oil passage 34 inside and an oil passage 35 inside the connecting portion 2B. In addition, the hydraulic chamber 12a of the power cylinder 12
, 12b is an oil passage 37a in the rear wheel steering rod 9.
7b and the oil passages 38a and 38b in the connecting part 2G, respectively, to the oil chamber 36, and the oil in the oil chamber 36 is connected to the oil passage 39 in the connecting part 26 and the oil in the rear wheel steering rod 9. Road 40. The oil is returned into the oil tank 31 from the oil passage 32b via the oil passage 41 in the casing 8a. With such a configuration, the rear wheel steering rod 9 is connected to the III control rod 1 which is the output shaft of the displacement control means C.
5 is displaced left and right within the casing 8a. In addition, the amount of displacement! II Ij An oil pan 43 is located below the storage casing 8b that houses the pulp housing 27 of the hand means and hydraulic drive means.
The oil pan 43 is filled with oil to lubricate each mechanical part.

Next, the configuration of each part in the embodiment of the present invention will be explained in more detail.

FIG. 2 is a diagram showing the rear wheel steering rod 9, hydraulic drive means, and displacement amount control means C provided in the housing 8, with the right half shown as FIG. 2A and the left half shown as FIG. 2B. be. Further, FIGS. 3 and 4 are cross-sectional views taken along the line ■--■ and the line ■--■ in FIG. 2B, respectively.

First, in FIG. 2A, the power cylinder 12, spool pulp 25,
Details of the pulp housing 27 and each oil passage are shown, and the rear wheel steering rod 9 is divided into two left and right parts 9a and 9b in order to facilitate the formation of oil passages inside the rod. The two rod portions 9a and 9b are integrally connected by being screwed into the cylindrical body 20 from the left and right sides. This cylindrical body 20 is constructed integrally with the pulp housing 27 of the hydraulic drive means described above and the connecting portion 2G. In the cylindrical body 20, the end surfaces of both rod portions 9a and 9b face each other with a predetermined gap apart without contacting each other, and the rod portion 9a.

A chamber 28 is formed between the O-ring and the inner circumferential surface of the cylindrical body 20 by attaching an O-ring to the outer circumferential surface near the end surface of the cylindrical body 9b.

The left rod portion 9a has an oil passage 37a in FIG.
, 112 of the power cylinder 12 from the end face facing the chamber 28 to form a part of the hydraulic chambers 12a, 112, and 37b, respectively.
Two passages 46, 47 extending along the axis are provided leading to b. The passages 4B and 47 are connected to the hydraulic chamber 12a11 by holes 48 and 49 that are perpendicular to the axis.
2b, respectively. Also, only passage 4G is room 2.
8, but a passage 47 that communicates with the hydraulic chamber 12b
In order to isolate this passage 41 from the chamber 28, a spherical stopper 29 is fitted from the end face side of the rod portion 9a.

Similarly, the right rod portion 9b is also provided with chambers 2 to form a part of the oil passages 34 and 40 shown in FIG.
There are passages 51, 52 extending to the right from the end facing B, both of which are closed at the end by a stopper 29 in order to isolate them from the chamber 28.

On the other hand, a cylindrical body 2 connecting the rod portions 9a and 9b
Four oil passages 38b, 3 are provided on the inner circumferential surface of the valve 0, which communicate with the oil chamber 3G in the valve housing 27 through the connecting portion 26.
8a135 and 39 are opened in this order,
(see figure), the oil passage 38a of which is open to communicate with the chamber 28, so that the oil pressure chamber 12a is connected to the hole 48.
, an oil passage 37a constituted by passage 461 and chamber 28;
The oil chamber 3 in the valve housing 21 through the oil passage 38a.
6. Further, an annular chamber 52 is formed by a groove and an O-ring on the outer peripheral surface of the left rod portion 9a at a position facing the oil passage 38b, and a hole is provided in the rod portion 9a to communicate this chamber 53 with the passage 47. As a result, the hydraulic chamber 12b communicates with the oil chamber 36 in the valve housing 21 through the oil passage 37b and the oil passage 38b, which are constituted by the hole 49, the passage 41, and the annular chamber 52. aisle 5
1.52 is also provided with two annular chambers 53.5 at a position facing the oil passage 35.39.
4 are formed, and the chamber 53 and the passage 51 communicate with each other, and the chamber 54 and the passage 52 communicate with each other through holes made in the rod portion 9b. The passages 51, 52 are
．． Hole 5 drilled in rod portion 9b at the right end of 52
5.56 respectively communicate with the outer peripheral surface of the rod portion 9b, while the openings 57.41 of the oil passages 33.41 provided in the cylindrical casing 8a are connected to the inner peripheral surface of the casing 8a.
58 is extended in the axial direction of the rod portion 9b, and despite movement of the rear wheel steering rod 9 to the left, the oil passage 33 in the casing 8a always communicates with the passage 51, and the oil in the casing 8a It is provided that channel 41 always communicates with channel 52. With such a configuration, the oil passage 32 extending from the oil pump 30 is connected to the oil passage 33 and fLs5.
, a passage 51, and an oil passage 34 formed by an annular chamber 53.
and an oil passage 40 that communicates with an oil chamber 36 in the valve housing 27 through an oil passage 35, and the oil chamber 36 is formed by an oil passage 39, an annular chamber 54, a passage 52, and a hole 5G.
and communicates with the oil tank 31 through oil passages 41 and 42.

The structure and function of the valve housing 21, oil chamber 36, and spool valve 25, which constitute the hydraulic drive means DtrIIi4, are the same as those of the hydraulic drive means used in ordinary power steering devices, so we will not go into further details. Although description is omitted, in the case of this embodiment, the spool valve 25 is formed in a cylindrical shape, and a return spring 61 is provided inside the spool valve 25 between the control rod 15 and the valve housing 27, and the spool valve 25 is formed in a cylindrical shape.
1 moves together with the rear wheel steering rod 9, the spool valve 25 is configured to be able to return to the neutral position with respect to the valve housing 27 following the movement.

FIG. 2B, which shows the left half of the device according to the embodiment of the present invention, shows the detailed structure of the displacement amount 1III'wJ means C. The configuration of this displacement amount control means C was previously proposed by the applicant in the specification of Japanese Patent Application No. 59-48054, but as is clear from FIG. 2A, it is a spool valve using hydraulic drive means. The control rod 15 connected to the control rod 25 is held so as to be freely movable in the vehicle width direction, and its movement axis is shown as fLs. This displacement amount control means C includes a swinging arm 11, and this swinging arm 11
is pivotably attached to a holder 73 whose base end is attached to one end of a rotating shaft 72 by means of a pin 14 .

The rotation axis 72 to which the boulder 73 is attached is the movement axis L of the control rod 15! The pin 74 that pivots the swing arm 11 is rotatably supported by the housing 8 about an axis 9J2 orthogonal to the axis 9J2.
9J2, and at the intersection of axis 9.9J2.
It is supported by the boulder 13 so as to be orthogonal to z. Therefore, the rotation of the shaft 12 causes the axis of the pin 14 and the axis 9. The angle of inclination with respect to t changes. That is, bottle 1
The axis of the orbital surface centered at 4 is perpendicular to the axis (
The angle of inclination with respect to this plane (this plane is called the "reference plane") changes.

On the other hand, the tip of the swing arm 11 and the control rod 15 are
They are connected via ball joints 75 and 76 and a connecting member 17. Although the connection length of the connection member 17 is adjustable, it is assumed that sufficient rigidity in the axial direction is ensured. With such a connecting member 17, the distance between the ball joint 75 at the tip of the swing arm 71 and the ball joint 16 at the base end of the control rod 15 is always maintained constant. Therefore, if the ball joint 15 is displaced in the left-right direction in FIG. 2B, the control rod 15 will be moved in the left-right direction along the axis 1 in accordance with this displacement.

The connecting member 77 is supported by a rotation imparting arm 80 at a portion near the ball joint 75, and this arm 80 is a large diameter umbrella rotatably supported by a bin 81 fixed on the shaft 11A9J1. It is provided integrally with the gear 82. The connecting member 17 has an axis 51! , 1, and is supported by a ball joint 83 slidably provided in a direction orthogonal to 1, and the shaft 14 shown by a phantom line in FIG. 2B is an input shaft of this displacement amount control means C. 14, and this input shaft 14 is rotated in accordance with the rotation angle of the steering wheel 2, as is clear from FIG. A bevel gear 84 that engages with the bevel gear 82 is attached to the tip of the input shaft 14, and rotation of the steering wheel 2 is transmitted to the rotation imparting arm 80. Therefore, the swing arm 11 will swing around the pin 74 by an amount corresponding to the rotation angle of the steering wheel 2, but the rotation imparting arm 80 will rotate due to the rotation of the input shaft 14. When the swing arm 71 is rotated around the pin 74 in response to this, the axis of the pin 74 is aligned with the axis 9. s
When the ball joint 75 at the tip of the swing arm 71 only rotates on the reference plane, the control rod 15 remains stationary. However, if the axis of the bottle 74 is inclined with respect to the axis 1, the ball joint 75 will be displaced in the left-right direction in FIG. 2B as the swing arm 71 swings about the pin 74. This displacement is applied to the control rod 1 via the connecting member 77.
5, and the control rod 15 is transmitted to the axis 5! , 1 and actuates the spool valve 25 of the hydraulic drive means. Even if the swinging angle of the swinging arm 11 about the axis of the bin 74 is the same, the displacement of the ball joint 75 in the left-right direction in FIG. It will change as the rotation angle changes.

In order to change the inclination angle of the bin 74 with respect to the axis I L 1, that is, the inclination angle of the holder 13 with respect to the reference plane, a sector gear as a worm wheel is attached to the rotation shaft 72 of the holder 73, as is clear from FIG. 90 is attached, and a worm gear 91 that engages with this sector gear 90 is provided on the rotation shaft 92. A bevel tooth 1i93 is attached to this rotation shaft 92,
Further, the bevel gear 95 on the rotating shaft 94 of the pulse motor 21 provided for changing the steering ratio θR/θF mentioned above engages with the bevel gear 93, so that the holder 7
The angle of inclination with respect to the reference plane of No. 3 is changed. The motor 21 is attached to the left end of the housing 8 in a corner space between the cylindrical casing 8a and the storage casing 8b, and the rotation shaft 94 of the motor, which is the second input shaft to the displacement amount control means C, is aligned with the axis. 9,
It is arranged parallel to r. Also, holder 7
The shaft 12 of No. 3 extends into a cylindrical body 62 that extends upward integrally with the housing 8, and a steering ratio sensor 24 consisting of a potentiometer or the like is attached to the upper end. Holder 1
3, that is, the rotation angle of the shaft 72, is detected by the steering ratio hinge 24.

Figure 6 shows the vehicle speed and steering ratio θR when controlling the motor 21.
/θF (here, θF is the front wheel steering angle, and θ is the rear wheel steering angle). When the vehicle speed is low, in order to improve the turning performance of the vehicle, the rear wheels need to be steered in the opposite direction to the front wheels, that is, in an opposite phase, and therefore the steering ratio is negative. When the vehicle speed reaches approximately 40 KIR/hour, the steering ratio becomes zero, and the rear wheels are not steered regardless of the steering angle of the front wheels. When driving at high speeds, the rear wheels are steered in the same direction and in almost the same phase as the front wheels in order to improve the grip of the rear wheels during cornering and strengthen stability. In order to change the steering ratio according to the vehicle speed, a displacement means is provided, and the steering ratio sensor 24 used therein controls the motor 21 to obtain the desired steering jtJ. Since the tires play an extremely important role in driving, it is necessary to protect them from damage caused by stones and the like thrown up by the tires while the vehicle is running. Therefore, as is clear from FIG. 3, the steering ratio sensor 24 is provided above the contact wheel steering rod 9.

As shown in FIG. 4, the input shaft 1 of the displacement ffi control means C
4, a lock bolt 101 comes into contact with the input shaft 14 from the outside in the radial direction. This lock bolt 101 is screwed from below into a lock hole 102 formed in the storage casing 8b, and its upper end portion is connected from the storage casing 8b to the storage casing 8b and the cylindrical casing 8.
The input shaft 14 can be moved in and out of the shell through hole 103 formed by the input shaft 14 and the input shaft 14, thereby forming a locking means E. That is, when the lock bolt 101 is tightened, the tip of the lock bolt 101 comes into contact with the outer peripheral surface of the small diameter portion 14a formed on the input shaft 14 and has a small circumferential diameter, and the input shaft 14 is tightened.
rotation will be prevented. Rock bolt 101
If the locking bolt 101 is tightened with a strong force, it is possible to cause the tip of the lock bolt 101 to bite into the outer peripheral surface of the small diameter portion 14a.

The above rock bolt 10? and the lock bolt 10
The arrangement of the locking means E, which consists of a storage casing 8b in which a locking hole 102 into which the locking means 1 is screwed, is arranged in the entire four-wheel steering system as shown in FIG.

Next, the operation of this embodiment will be explained.

In the four-wheel steering system shown in FIG. 1, the front wheel steering mechanism A and the rear wheel steering mechanism B are connected to the front wheel 1L.

After toe adjustment of 1R and rear wheels 7L and 7R, the shaft 19 and the input shaft 1 of the displacement fl control means C are
4 by connecting them with a conversal joint 18. At the time when the above connection is made, the input shaft 14 of the displacement amount control means C is locked by the locking means E so as not to rotate, and after the connection is completed, the locking by the locking means E is released. This lock is released by loosening the lock bolt 101 and removing it from the casing 8b. On the other hand, the locking means E locks the input shaft 14 by tightening the lock bolt 101, but this locking is performed before toe adjustment of the rear wheels 7L, 7R.

The input shaft 14 is locked in a state in which the rear wheel steering mechanism B can function normally, that is, after the connection with the front wheel steering mechanism A is completed, the front wheel IL is controlled by the front wheel steering mechanism.

This is done with the rear wheel steering mechanism B set at WJ so that the rear wheels 7L and 7R are steered with the initial characteristics in response to the steering of 1R. Specifically, the rear wheel steering rod 9 is placed in the neutral position shown in the figure (i.e., the position that is used when steering the rear wheels 7m and 7R), and when no hydraulic pressure is applied to the rear wheel steering rod 9. The rear wheel steering rod 9 is positioned at a stationary position due to the elastic force of the return spring 42, and
By setting the displacement m control means C to the hydraulic drive means control reference state corresponding to the neutral position of the rear wheel steering rod 9, it is possible to bring the rear wheel steering mechanism B into a state where it can function normally.

To set the displacement ff1llJ control means C to the hydraulic drive means υll1l reference state, the following operation may be performed.

That is, in FIG. 7 showing the function of the displacement fiw control means C in detail, the bin 14 is moved by the drive of the pulse motor 21.
is rotated by an appropriate angle from the illustrated state to obtain a positive or negative steering ratio. Next, while oil is supplied from the oil pump 30 to the hydraulic drive means, the input shaft 14 of the displacement amount control means C is rotated in either the left or right direction, and at this time, the amount of displacement of the rear wheel steering rod 9 in the vehicle width direction is Measure. A graph as shown in FIG. 8 is obtained from these measured values. That is, even if the input shaft 14 is rotated in either the left or right direction, the rear wheel steering rod 9 will be displaced as the rotation angle changes, but within a certain angular range, the rear wheel steering rod 9 will be displaced relative to the rotation angle change of the input shaft 14. There is a so-called dead zone in which the rear wheel steering rod 9 is not displaced. This dead zone corresponds to the rotation angle flI range of the input shaft 14 when the pressure of the oil supplied to the power cylinder 12 as the input shaft 14 rotates becomes smaller than the precompression force applied to the return spring 42. It is something.

Therefore, if the input shaft 14 is fixed at the angle α0 between the ends of this dead zone and the midpoint of α2, the pressure of the oil supplied to the power cylinder 12 will be the lowest, and the displacement ffi M III means the rear wheel This means that the reference state corresponding to the neutral position of the steering rod 9, that is, the hydraulic drive means control reference state is set.

The graph in FIG. 8 shows that the larger the rotation angle of the bin 74, the
In other words, the larger the absolute value of the steering ratio, the higher the ratio of the displacement of the rear wheel steering rod 9 to the rotation angle of the input shaft 14, which makes the rising of both sides of the dead zone more clear, which is more preferable. Note that whether the steering ratio is positive or negative only causes the graph to turn half way up or down, and it may be either positive or negative. Also, the horizontal axis of the graph in FIG. 8 shows the respective hydraulic chambers 12a, 1 of the power cylinder 12.
The oil pressure at a3 may be taken as 2b, and in this case also a dead zone can be obtained on the graph.

As another method for setting the displacement amount control means C to the hydraulic drive means control reference state, in FIG.
1 hangs vertically (on the installation side, in this state, the displacement fl
u i, II III The hydraulic drive means control reference state corresponds to the neutral position of the rear wheel steering rod 9. ), but according to the method described in Section 1F that uses a dead zone, it is possible to adjust the rotational angle position of the input shaft 14 so that It is possible to determine an accurate hydraulic drive means control I reference state.

In this way, the rear wheel steering rod 9 is positioned at the neutral position and the displacement ffl1. After setting the II control means C to the hydraulic drive means control reference state, the input shaft 14 is locked by the locking means E, and then the contact wheel 7L.

As already mentioned, the toe adjustment of the front wheels 1L and IR is performed, the input shaft 14 is connected to the shaft 19, and then the lock is released by the locking means E. However, for the toe adjustment of the front wheels 1L and IR, Toe adjustment may be performed at any time before connection with the shaft 19 is made.

As described in detail above, according to this embodiment, it is possible to hold the rear wheel steering mechanism B in an appropriate state by the locking means E using the lock bolt 101, so that the front wheel steering mechanism A and After the connection of the rear wheels 71.
7R is the front wheel IL, and according to the steering of 1R, the first I shown in Figure 6
It becomes possible to steer according to the steering ratio characteristics of I. In addition, the above effects can be achieved by the simple operation of tightening and handling the lock bolt 101, resulting in extremely good workability.

Note that the lock bolt 101 is inserted into the lock hole 1 of the storage casing 8b after the front wheel steering mechanism is connected to the rear wheel steering mechanism B.
Instead, a cap bolt having a short bolt shaft portion whose tip does not reach the input shaft 14 even when fully tightened is tightened in the lock hole 102 to take measures such as dustproofing. Furthermore, when tightening the lock bolt 101, it is possible to tighten the small diameter part 14a of the input shaft 14 a little more strongly and form a notch on the outer circumferential surface of the small diameter part 14a. Even if the lock bolt 101 is to be tightened again after being removed, it is possible to fit the lock bolt 101 into the notch and tighten it at the same location on the outer peripheral surface of the small diameter portion 14a.

In this embodiment, the displacement ffi IiJ control means C is provided with a variable steering ratio function, but even in the case of a fixed type four-wheel steering 8wl with a constant steering ratio, the assembly shown in this embodiment may be used. It goes without saying that the attaching method can be adopted.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing the overall configuration of an example of a four-wheel steering device for an automobile according to the present invention, and FIG. 2 shows a part of the rear wheel steering mechanism of the device, and FIG. FIG. 2A is a front view showing a right half of the rear wheel steering mechanism as a partial cross section;
Figure B is a front view showing the left half of the same as a partial cross section, Figure 3 is a sectional view taken along line ■-■ in Figure 213, Figure 4 is a sectional view taken along line IV-IV in Figure 2B, and Figure 5 is a sectional view taken along line IV--IV in Figure 2B. The figure is a partial cross-sectional bottom view showing the motor drive part of Fig. 2B, Fig. 6 is a graph showing the relationship between vehicle speed and steering ratio, and Fig. 7 is a perspective view functionally showing the configuration of the displacement m control means. , FIG. 8 is a graph for determining the hydraulic drive means control reference state. A... Front wheel steering mechanism B... Rear wheel steering mechanism C...
Displacement amount control means D... Hydraulic drive means E... Locking means 1L, 1R... Front wheels 7L, 7R... Rear wheels 19... Shaft helmet 5 Figure 6

Claims (1)

[Scope of Claims] 1) a front wheel steering mechanism that steers the front wheels in response to steering wheel steering; a rear wheel steering mechanism that steers the rear wheels in response to the steering of the front wheels by the front wheel steering mechanism; A four-wheel steering device for an automobile, comprising a front wheel steering mechanism and a shaft connected to the rear wheel steering mechanism and transmitting the amount of steering of the front wheels by the front wheel steering mechanism to the rear wheel steering mechanism. The rear wheel steering mechanism includes a rear wheel steering rod that extends in the vehicle width direction, has both ends connected to rear wheel support members, is biased to a predetermined neutral position in the vehicle width direction, and is movable in the vehicle width direction. and,
a hydraulic drive means for displacing the rear wheel steering rod from the neutral position in the vehicle width direction by applying hydraulic pressure to the rear wheel steering rod; a displacement control means for controlling the drive of the hydraulic drive means; and a lock for locking the displacement control means near a connecting portion of the displacement control means to the shaft to stop the operation of the displacement control means. A four-wheel steering device for an automobile, comprising: means. 2) a front wheel steering mechanism that steers the front wheels in response to steering wheel steering; a rear wheel steering mechanism that steers the rear wheels in response to the steering of the front wheels by the front wheel steering mechanism; and the front wheel steering mechanism and the a shaft that is connected to a rear wheel steering mechanism and transmits the amount of steering of the front wheels by the front wheel steering mechanism to the rear wheel steering mechanism, the rear wheel steering mechanism extending in the vehicle width direction. A rear wheel steering rod that is movable in the vehicle width direction and whose both ends are connected to rear wheel support members and is biased to a predetermined neutral position in the vehicle width direction; a hydraulic drive means for displacing the wheel steering rod from the neutral position in the vehicle width direction; and a displacement control that is connected to the hydraulic drive means and the shaft and controls the drive of the hydraulic drive means according to the amount of steering of the front wheels. and a locking means for locking the displacement amount control means in the vicinity of the connecting portion of the displacement amount control means to the shaft to stop the operation of the displacement amount control means. An assembling method comprising: positioning the rear wheel steering rod at the neutral position with the shaft and the displacement control means unlocked and the locking means unlocking the displacement control means; After setting the displacement amount control means to a hydraulic drive means control reference state corresponding to a neutral position of the rear wheel steering rod, the displacement amount control means is locked by the locking means, and in this state, toe adjustment of the rear wheels is performed. A four-wheel steering system for an automobile, characterized in that the front wheels are toe-adjusted, the displacement amount control means and the shaft are then connected, and the displacement amount control means is unlocked by the locking means. How to assemble.