JPH0450081A - Neutral position adjusting method for vehicle rear wheel steering device - Google Patents

Abstract

PURPOSE:To realize connection between a mechanical system and a hydraulic system without misalignment between them by adjusting neutral position of the mechanical system displacing a rear wheel steering shaft with a displacement transmitting means temporarily assembled, thereafter adjusting and assembling the displacement transmitting means so as to absorb misalignment between neutral positions op the mechanical system and the hydraulic system. CONSTITUTION:When a rear wheel steering device is assembled, adjustment of neutral position of a mechanical system is first performed on the basis of a specified operating condition, with hydraulic pressure not applied. Then, with hydraulic pressure applied, the displacements of a rear wheel steering shaft 13 and a supporting support 38 are respectively measured, and the neutral position of the rear wheel steering shaft 13, at which the rear wheel steering shaft 13 is not displaced even when the supporting support 38 is displace, is detected. Thereafter, with the rear wheel steering shaft 13 located at neutral position, the supporting support 38 which is in a temporarily assembled, is assembled, and the engaging end part C of the cross-shaped lever 14A of a lever-assembly 14 or a displacement transmitting means, is rotatably and unmovably assembled. Thus, the mechanical system and the hydraulic system are connected to each other, and misalignment between the neutral position of the hydraulic system and the neutral position of the mechanical system are absorbed by adjusting the assembling state of the supporting support 38.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a neutral adjustment method for a vehicle rear wheel steering system in which a rear wheel steering shaft for steering the rear wheels is controlled by two systems, a mechanical system and a hydraulic system. It is related to.

(Prior Art) Conventionally, as described in, for example, Japanese Unexamined Patent Publication No. 1-273772, a mechanical system that displaces a rear wheel steering shaft that steers the rear wheels has an input shaft that inputs the amount of steering angle of the front wheels. ,
An output rod member that receives input from the input shaft and strokes in the axial direction; and an output rod member that is linked to and swingably supported by the output rod member, and the stroke amount of the output rod member due to rotation of the input shaft is determined by the swing angle of the output rod member. a yoke assembly configured to transmit the stroke amount of the output rod member to the rear wheel steering shaft by a displacement transmitting means linked to the output rod member; or a power steering means for hydraulically assisting the displacement of the rear wheel steering shaft, and a hydraulic switching valve for controlling the power steering means, the hydraulic switching valve being linked to the displacement transmitting means, A vehicle rear wheel steering system in which the mechanical system and the hydraulic system are connected is known.

(Problem to be solved by the invention) In such a mechanical system, depending on the rotation angle of the manual shaft and the swing angle of the yoke assembly, the stroke amount of the output rod member or the displacement amount of the rear wheel steering shaft can be determined. In the hydraulic system, the rear wheel steering shaft is hydraulically assisted by the power steering means so that the rear wheel steering shaft is displaced by an amount corresponding to the displacement amount.

Therefore, in order to accurately perform rear wheel steering, that is, displacement of the rear wheel steering shaft, it is necessary to maintain a neutral (zero) It is necessary to connect both systems so that the neutral (zero phase) of the hydraulic system that hydraulically assists the displacement of the rear wheel steering shaft coincides with the neutral phase (phase) of the rear wheel steering shaft.

The present invention provides a vehicle rear wheel steering system as described above, in which there is no deviation in control of the rear wheel steering shaft between a mechanical system that displaces the rear wheel steering shaft and a hydraulic system that assists in displacement of the rear wheel steering shaft. An object of the present invention is to provide a neutral adjustment method for a vehicle rear wheel steering system.

(Means for Solving the Problems) The present invention provides a mechanical system for displacing a rear wheel steering shaft for steering rear wheels, which includes an input shaft for inputting the amount of steering angle of the front wheels, and an input shaft for receiving the input from the input shaft. an output rod member that strokes in the direction; and a yoke assembly that is linked to the output rod member and is swingably supported, and that controls the stroke amount of the output rod member due to rotation of the input shaft according to the swing angle of the yoke assembly, The displacement transmission means linked to the output rod member is configured to transmit the stroke amount of the output rod member to the rear wheel steering shaft, and the hydraulic system that assists the displacement of the rear wheel steering shaft is configured to A power steering means for hydraulically assisting the steering of the steering shaft, and a hydraulic switching valve for controlling the power steering means, the hydraulic switching valve being linked to the displacement transmitting means to connect the mechanical system and the hydraulic system. This is based on a vehicle rear wheel steering system.

The invention of claim (1) performs neutral adjustment of a mechanical system based on a predetermined operating state in a state in which hydraulic pressure is not applied and a displacement transmitting means is temporarily assembled, and then in a state in which hydraulic pressure is applied. The displacement transmitting means is adjusted so as to absorb the deviation between the neutral position of the mechanical system and the neutral position of the hydraulic system, and is finally assembled to connect the hydraulic system to the mechanical system.

The invention of claim (2) detects the neutral angular position of the yoke assembly and the neutral angular position of the input shaft in the neutral adjustment of the mechanical system, and detects the neutral angular position of the input shaft in the neutral adjustment of the mechanical system. The displacement transmitting means is finally assembled with the wheel steering shaft in a neutral state.

(Function) According to the invention of claim (1), the mechanical system is neutralized for displacing the rear wheel steering shaft in a state in which hydraulic pressure is not applied and the displacement transmitting means is temporarily assembled, based on a predetermined operating state. After making the adjustment, with the hydraulic pressure applied,
The invention of claim (2) is characterized in that the displacement transmitting means is adjusted so as to absorb the deviation between the neutral of the mechanical system and the neutral of the hydraulic system, and is fully assembled, so that the mechanical system includes a hydraulic system. To adjust the neutral position of the yoke assembly, adjust the neutral angle position of the yoke assembly, and adjust the neutral angle position of the input shaft.When connecting the hydraulic system to the mechanical system, set the rear wheel steering shaft in the neutral state, and adjust the neutral angle position of the input shaft. will be fully assembled.

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

A vehicle rear wheel steering device 1, which is a premise of the present invention, as shown in the schematic configuration in FIG. 14, and a hydraulic switching valve 1 as a hydraulic assist means.
5, the rear wheel steering device 1 steers the rear wheels (not shown) according to a predetermined steering ratio characteristic, that is, according to the front wheel steering angle, and changes the steering ratio according to the vehicle speed. It is configured to allow

The rear wheel steering shaft 13 extends in the vehicle width direction, and is connected to the left and right sides through a pair of tie rods and knuckle arms at both ends.
It is connected to a pair of rear wheels, and the rear wheels are steered by stroke displacement of the rear wheel steering shaft 3 in the vehicle width direction.

The stroke displacement of the rear wheel steering shaft 13 in the vehicle width direction is performed by the steering ratio variable means 11 and the power steering means 12.

The steering ratio variable means 11 changes the steering ratio when steering the rear wheels, and has an output rod member 16 that is stroke-displaced in the vehicle width direction according to the amount of steering angle of the front wheels.

As will be described later, the ratio of the displacement amount of the output rod member 16 to the steering angle amount of the front wheels (corresponding to the steering ratio) changes depending on the swing angle of the yoke assembly 18 that is swing-driven by the stepping motor 17. It is configured as follows. The amount of rotation of the stepping motor 7 is appropriately controlled based on a vehicle speed signal output from a vehicle speed sensor (not shown), and the actual amount of rotation of the stepping motor 17 is controlled by a steering ratio sensor (not shown). The detection signal is used for feedback control.

Power steering means that controls switching of the hydraulic switching valve 15 according to the stroke displacement amount of the output rod member 16 in the steering ratio variable means 11, and generates a steering force using hydraulic pressure by the hydraulic switching valve 15. 12, the displacement of the rear wheel steering shaft 13, and therefore the steering of the rear wheels, is hydraulically assisted.

The steering ratio variable means 11 includes the output rod member 16,
Stepping motor 17 and yoke assembly 18 (
In addition to the swing shaft member 22, the pendulum arm 23, and the swing gear 31), it also includes a bevel gear 21 and a connecting rod 24. As shown in detail in FIG. 7, it is housed in a casing 25.

The output rod member 16 of the steering ratio variable means 11 is supported by the casing 25 so as to be slidable in the axial direction, and by making a stroke displacement in the axial direction, the output rod member 16 transmits the displacement transmitting means 14 as described later. Through the rear wheel steering shaft 13
is displaced in its axial direction (vehicle width direction), thereby steering the rear wheels linked to both ends of the rear wheel steering shaft 13.

The bevel gear 21 is connected to the lever 2 of the output rod member 16.
8 to the output rod member] 6 side, it is supported by the output rod member 16 via a cylindrical support member 52 so as to be rotatable along with the output rod member 16 and about an axis coaxial with the output rod member 16.

A binion 27 at the rear end of the input shaft 26 that meshes with the bevel gear 21 and inputs the amount of steering angle of the front wheels rotates around the axis as the steering wheel rotates.

The swing shaft member 22 has an axis that can be positioned coaxially with the output rod member 16, and is fixed to the swing gear 31. This swing gear 31 is connected to the stepping motor 17
A swing shaft 31a that is perpendicular to the plane of the paper and intersects with the axis g1 of the swing shaft member 22 meshes with the worm 32 that rotates due to the drive of the swing shaft member 22.
(see FIG. 4), and thereby the swing shaft member 22 is also rotated at the same time.

Note that the shaft 31a of the swing gear 31 is coupled to the motor shaft 17a of the stepping motor 17 via a coupling 54 (see FIG. 6).

The pendulum arm 23 is connected to the swing shaft member 22 so as to be able to swing around the axis 91 of the swing shaft member 22, and the axis Ω2 of the pendulum arm 23 is connected to the swing axis 91 of the swing shaft member 22. The connection position to the swing shaft member 22 is determined so as to pass through the intersection of the axis G and the swing shaft member 22.

Like the rear wheel steering shaft 13, the connecting rod 24 has an axis parallel to the axis g3 of the output rod member 16,
It is connected to the output rod member 16, bevel gear 21, and pendulum arm 23, and links the output rod member 6 and the yoke assembly 18. Connection to the output rod member 16 is achieved by splitting and coupling the intermediate portion of the connecting rod 24 to a lever 28 fixed to the end of the output rod member 16, and connection to the bevel gear 21 is achieved by connecting the connecting rod 24 to a lever 28 fixed to the end of the output rod member 16. The connecting rod 24 is connected to the pendulum arm 23 by inserting one end of the connecting rod 24 into an insertion hole formed in the extension portion 52a of the supporting member 52, and the connecting rod 24 is connected to the other end of the connecting rod 22 so as to be rotatable in all directions. This is done by inserting the pendulum arm 23 into the insertion hole of the ball joint member 33 that has been inserted.

Therefore, the connecting rod 24 is fixed to the output rod member 16, but is slidable relative to the bevel gear 21 in the direction of the axis g4, and is slidable relative to the pendulum arm 23 in the direction of the axis g2. It is possible. Note that the axis g2 of the pendulum arm 23 changes from the axis Ω due to the rotation of the swing shaft member 22.
3, and the pendulum arm 23 slides in this tilted direction, but even in this case, the included angle change between the axis g2 and the axis g4 is absorbed, so that the pendulum arm 23 A component of the force transmitted to the connecting rod 24 in a direction orthogonal to the axis 113 of the output rod member 16 is absorbed at the connection point, allowing relative movement in the orthogonal direction.

In this way, the pendulum arm 2 in the steering ratio variable means 11
3 (yoke assembly 18) and the connecting rod 24 are connected so that they can move relative to each other in the direction perpendicular to the axis I3, so that when the pendulum arm 23 rotates, the The locus of the connecting rod 24 and the connecting point is a circular locus or an elliptical locus on the outer circumferential surface of a cylinder having a predetermined radius centered on the axis 13.

As described above, by connecting the pendulum arm 23 and the connecting rod 24 so that they can move relative to each other in the direction orthogonal to the axis p3 of the output rod member 16, the axis p4 of the connecting rod 24 and the output rod member The angle between the output rod member 16 and the axis 13 can be made constant, thereby making it possible to prevent left-right deviations from occurring in the displacement of the output rod member 16.

Further, in the output rod member 16, one end of the output rod 36 is connected to the connecting rod 24 via the lever 28, and the other end of the output rod 36 is fitted into the cylindrical rod guide 35 so as to be displaceable in the direction of the axis I3. The ends of the rod guide 35 and the output rod 36 are supported by the casing 25.

The rod guide 35 includes a first cylindrical member 35b having an engaging portion 35a that engages with the engaging end A of the displacement transmitting means 14, and a second cylindrical member 35c screwed onto the first cylindrical member 35b. A spring 37 is interposed between the output rod 36 and the output rod 36.

Therefore, when a displacement in the direction of the axis g3 is transmitted to the output rod 36 by the connecting rod 24, it is normally transmitted from the output rod 36 to the mouth/bottom guide 35 via the spring 37, and from this rod guide 35 to the engaging portion 35a. The displacement is transmitted to the engaging end A of the displacement transmitting means 14 which is engaged with the displacement transmitting means 14 . However, the movement of the engagement end A of the displacement transmission means 14 is restricted, so that when the output rod 36 is displaced, the spring 3
When a load equal to or greater than the spring force of 7 is applied to the rod guide 35, the displacement of the output rod 36 is absorbed by the contraction of the spring 37 and is not transmitted to the rod guide 35.

Further, the hydraulic switching valve 15 is connected to the valve housing 4.
1 and the valve housing 4 in the valve housing 41.
1, the valve spool 4 is housed so as to be displaceable in the direction of the axis Ω5 parallel to the axis ρ3 of the output rod member 16.
It consists of 2. The valve spool 42 is displaced by the output rod member 16 and the rear wheel steering shaft 13 via a displacement transmission means 14, which will be described in detail below. The supply of hydraulic pressure to the power steering means 2 is controlled by this displacement of the valve sprue 42.

Further, a centering spring 45 is provided on this rear wheel steering shaft 13, and if the hydraulic pressure in the hydraulic switching valve 15 or the power steering means 12 disappears, or if the mechanical system of this rear wheel steering device 1 is damaged or malfunctions, When the hydraulic system is drained and the hydraulic pressure in the cylinder of the power steering means 12 disappears, the centering spring 45 moves the rear wheel steering shaft 13 to the neutral position, that is, the rear wheels are not steered and are traveling straight. It is configured to be positioned in a certain position and to provide a so-called fail-safe.

The cylinder of the power steering means 12 displaces the rear wheel steering shaft 13 in the vehicle width direction by hydraulic pressure, and the piston 46 is directly fixed to the rear wheel steering shaft 13.
Left and right oil chambers 44 and 43 are formed on the left and right sides of this piston 46.

In addition to the output rod member 16 (rod guide 35), the displacement transmission means 14 engages with the valve spool 42, the rear wheel steering shaft 13, and the vehicle body (support support 38), and is caused by the displacement of the output rod member 16. Above valve spool 4
2 in a predetermined direction, and is also actuated in a direction to displace the valve spool 42 in the opposite direction due to the displacement of the rear wheel steering shaft 13 caused by the displacement of the valve spool 42. It is structured as follows.

Specifically, the displacement transmitting means 14 has a cross lever 14a consisting of a vertical lever and a horizontal lever, and the engagement end A, which is one end of the vertical lever, is connected to the rod guide 35 of the output rod member 16, and the other end is connected to the rod guide 35 of the output rod member 16. The engagement end B, which is the end, is connected to the rear wheel steering shaft 13,
An engaging end C, which is one end of the horizontal lever, is engaged with a support support 38 fixed to the vehicle body, and an engaging end, which is the other end, is engaged with the valve spool 42. The engaging ends A, B, and D are each connected to the output rod member 1.
The rod guide 35 of No. 6, the rear wheel steering shaft 13, and the valve spool 42 are immovably engaged in the axial direction, but movable and rotatable in other directions, and the engaging end C is They are engaged for rotation and non-movement by a ball joint (not shown).

Therefore, if the output rod member 16 is displaced to the right from a state where both the valve spool 42 and the rear wheel steering shaft 13 are in the neutral position, the engagement end A of the cross lever 14a will move to the right together with the output rod member 16. Displaced and engaged end A
Since the tire reaction force and the reaction force from the centering spring 45 are acting on the rear wheel steering shaft 13 when the rear wheel steering shaft 13 is displaced, this engagement end B is immobile in the axial direction, and the engagement end C is also supported 38 (vehicle body) and is immovable, the cross lever 14a is tilted about the straight line connecting the engaging end B and the engaging end C. In other words, the cross lever 14a moves the valve spool 42 in a predetermined direction. The engagement end portion displaces the valve spool 42 to the right.

When the valve spool 42 is displaced rightward from the neutral position in this way, the oil pressure in the right bending chamber 43 increases, and the left oil chamber 4
4 decreases, and a hydraulic pressure is generated in the power steering means 12 that pushes the rear wheel steering shaft] 3 to the left. The hydraulic pressure that pushes the rear wheel steering shaft 13 leftward increases in accordance with the increase in the rightward displacement of the valve spool 42, resulting in a balance position.

When the valve spool 42 is displaced to the right by a predetermined amount from the neutral position to the balance position, the hydraulic pressure of the power steering means 12 generated thereby causes an external force (centering spring force or tire (reaction force, etc.).

When the valve spool 42 is further displaced to the right from this state, the hydraulic pressure generated in the bowler steering means 12 becomes greater than the external force acting on the rear wheel steering shaft 13. is displaced to the left by the hydraulic pressure.

Then, when the rear wheel steering shaft 13 is displaced to the left, the engagement end B of the cross lever 14a is connected to the rear wheel steering shaft 13.
At this time, the output rod member 16 is affected by the steering force of the steering wheel, the tire reaction force of the front wheels, etc., so the engaging end A remains stationary, and the engaging end C also remains unchanged. Since it is stationary, the cross lever 14a tilts about the straight line connecting the engagement end A and the engagement end C, and when it returns to the balance position, the displacement of the rear wheel steering shaft 13 stops.

From this state, when the output rod member 16 is further displaced to the right and the valve spool 42 is displaced to the right, the rear wheel steering shaft 13 is displaced to the left in the same manner as above, and the valve spool 42 is returned to the balance position. By stopping, and repeating this operation, the rear wheel steering shaft 13 is displaced by an amount corresponding to the amount of displacement of the output rod member 16, and the rear wheels are steered in accordance with the amount of displacement.

When the output rod member 16 is displaced to the left, the cross lever 14a1, the valve spool 42 and the rear wheel steering shaft 1
3 is just the opposite of the above case, and the operating principle is the same, so the explanation will be omitted. The movement of this valve spool is described in the prior art (Japanese Patent Application Laid-Open No. 1-273
It is basically the same as that of Publication No. 772).

The steering ratio changing control by the above-mentioned steering ratio variable means] 1 can be performed based on various factors, and various changing control patterns can be considered.

In this embodiment, based on the vehicle speed, the rear wheels are steered in the opposite phase to the steering wheel and front wheels in low speed ranges to improve turning performance, and in high speed ranges, they are steered in the same phase to improve driving stability. Controlled to improve performance. Note that in this case, the bundle steering and the front wheel steering are always in the same phase.

Next, in the rear wheel steering system 1, a neutral adjustment method between the mechanical system and the hydraulic system, which affect the accuracy of the controlled steering amount of the rear wheels, will be described. In addition, this is the support support 38
This is done in a state where the cover 53 is not yet attached to the casing 25 and the hydraulic pressure is not applied.

(2) Detection of the neutral angular position of the yoke assembly 18 (oscillating gear 31) First, the input shaft 26 is fixed at an arbitrary angular position other than the neutral angular position, and the yoke assembly 18 is fixed at an arbitrary angular position other than the neutral angular position. Note that the hydraulic pressure is not working.

Then, the input shaft 26 is rotated by an arbitrary angle from the neutral angle position, and the rotation angle θ of the input shaft 26 and the displacement amount δ1 of the output rod member 16 (rod guide 35) at that time are measured and stored.

Thus, the yoke assembly] 8 is rotated from the neutral angular position by an amount of displacement -δ1 of the output rod member 16.

Then, the input shaft 26 is rotated by -θ, and the displacement amount δ2 of the output rod member 16 at this time is stored.

The output rod member 16 rotates the yoke assembly 18 by a displacement of -δ22/(δ1+62). The angle of the yoke assembly 18 found here is the true neutral angular position (zero phase).

The reason why a true neutral angular position (zero phase) can be obtained by the above equation -δ22/(δl+62) is as follows (see FIG. 7).

Output rod member 16 at two yoke angles φ and φ0 (
The displacement amount of the rod guide 35) can be expressed as follows.

δl −A ftanφ0+tan(φ−φ0)lfl
)δ'l −B (tanφ0+tan(φ−φ0)
l(21 From formulas (1) and (2), δ1/δ2−A/B (3) δ2 can also be expressed as follows.

δ2-Atanφ0+Btanφ0,', tanφ0-δ2/(A+B)
(4) Multiplying both sides of equation (4) by B, we get B tanφ0−δ2−B/ (A+B)−δ2/
(A/B+1) (5) Substituting equation (3) into equation (5), B tanφ0−δ2/(δ1/δ2+1)−δ22/
(δ1+62) ■Detection of the neutral angular position of the input shaft 26 If the relationship between the stroke displacement amount of the output rod member 6 and the rotation angle of the input shaft 26 is expressed in a graph as shown in FIG. 8, the input shaft The neutral position of 26 is the input shaft 2
Rate of change of stroke displacement amount of output rod member 16 with respect to rotation angle of 6 (inclination of sine curve L1 in FIG. 8)
It can be seen that this is the position where the maximum value (steepest slope point) is reached.

Therefore, a stepping motor and an encoder (not shown) can be attached to the input shaft 26 to measure the rotation angle of the input shaft 26, and a displacement meter (not shown) can be attached to the end of the output rod member 16. By applying this method, the stroke displacement amount of the output rod member 16 can be measured. Note that the hydraulic pressure is not working.

Thus, the yoke assembly 18 is oscillated by the stepping motor 17, and while the yoke assembly 18 is fixed at a specific oscillation angular position (for example, the maximum in-phase angular position), the input shaft 26 is rotated over the entire rotatable range. The output rod member 16 rotates, and the stroke displacement amount of the output rod member 16 is detected accordingly. In addition, yoke assembly 18
The swing angle position of is detected by a signal from the stepping motor]7.

Thus, the rate of change of the stroke displacement amount of the output rod member 16 with respect to the rotation angle of the input cuff/yaft 26 is determined, and the angular position at which the rate becomes the maximum value is determined as the neutral angular position. This neutral angular position can be detected by, for example, linking an XY recorder to an encoder and a displacement meter, and drawing a sine curve L1 with the X axis as the rotation angle of the input shaft 26 and the Y axis as the displacement amount of the output rod member 16. (see Figure 8), or by linking a microcomputer to the encoder and displacement meter,
This can be done by directly calculating the rate of change using the microcomputer.

In the case of this method, in the above embodiment, the yoke assembly 18 is fixed at a swinging angle position corresponding to the maximum in-phase angular position, and the input shaft 26 is The neutral angular position is detected and set, but it is also possible to use other same-phase positions as a reference, or, if necessary, to detect the neutral angular position using an arbitrary opposite-phase position as a reference. Of course.

In addition, whether the yoke assembly 18 is placed in the angular position corresponding to the same phase side or the angular position corresponding to the opposite phase side, if the input shaft 26 is rotated over the entire rotatable range, Since the yoke assembly 18 passes through the neutral angular position, the input is made once each with the yoke assembly 18 fixed at a oscillating angular position corresponding to a specific in-phase position and another oscillating angular position corresponding to an opposite phase position. The shaft 26 is rotated through the entire rotatable range, and the relationship between the rotation angle of the input shaft 26 and the stroke displacement amount of the output rod member 16 is expressed in a graph as in the case described above, and the intersection point is taken as the neutral angular position. input shaft 26
It is also possible to detect the neutral angular position of.

■ Connection between mechanical system and hydraulic system With hydraulic pressure applied, the displacement of the rear wheel steering shaft 13 and the support support 38 is measured, and the displacement of the support support 38 is measured.
Detect the neutral position of the rear wheel steering shaft 13 in which the rear wheel steering shaft 13 does not displace even if the rear wheel steering shaft 13 is displaced. The support support 38 which was in the state is fully assembled, and the engagement end C of the cross lever 14a of the lever assembly 14 is brought into the assembled state in which it is rotatable but immovable. This connects the mechanical system and the hydraulic system, and neutralizes the hydraulic system (
The deviation between the zero phase) and the neutral state (zero phase) of the mechanical system can be absorbed by adjusting the assembly condition of the support support 38.

That is, the specific measurement system is as shown in FIGS. 10 and 11, in which a displacement meter 61 that detects the amount of displacement in the axial direction of the rear wheel steering shaft 13 is applied to the end of the rear wheel steering shaft 13. On the other hand, a locking member 6 that locks (temporarily assembles) the support support 38
2 is displaceably mounted via ball screw means 63.

The twisting rod 63a of the ball twisting means 63 is connected to the coupling 64.
The locking member 62 is connected to a stepping motor 65 for rotation through the threaded rod 63a, and the rotation of the threaded rod 63a causes the locking member 62 to move in the axial direction of the threaded rod 63a. The amount of rotation of the stepping motor 650 is measured by a row encoder 66, and the amount of displacement of the locking member 62 is detected by a non-contact distance sensor 67.

Here, as shown in FIG. 12, it is possible to absorb the neutral deviation between the mechanical system and the hydraulic system by assembling the support support 38 in this way. This is because there is a dead zone in which the steering shaft 13 is not displaced.

The rear wheel steering device 1 is adjusted in this way before being transported between work stations, or because it is impossible to maintain the neutral position of each member during transport between work stations. It was necessary to make the same adjustment at each work station, but a distance sensor was installed in the casing 25 to detect the displacement of the output rod member 16 (rod guide 35), and the neutral position of the output rod member 6 was measured after the adjustment was completed. By memorizing the information, it is possible to eliminate the need to make the same adjustment for each work station even if the work station is transported between work stations.

(Effect of the invention) As described above, the invention of claim (1) performs the neutral adjustment of the mechanical system in a state in which hydraulic pressure is not applied and the displacement transmitting means is temporarily assembled, and then in a state in which hydraulic pressure is applied. In this state, the displacement transmission means was adjusted to absorb the deviation between the neutral of the mechanical system and the neutral of the hydraulic system, and the hydraulic system was connected to the mechanical system. It is possible to absorb the deviation between the neutral position of the hydraulic system and the neutral position of the hydraulic pressure by assembling the displacement transmission means, and it is possible to connect the hydraulic system to the mechanical system without causing a deviation in the neutral position of both systems. .

According to the invention of claim (2), when the hydraulic system is connected to the mechanical system, the displacement transmitting means is fully assembled with the rear wheel steering shaft in the neutral state. The hydraulic system can be connected in a neutral state.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a rear wheel steering device of a vehicle, FIG. 2 is a sectional view of a steering ratio variable means,
Figure 3 is a cross-sectional view taken along line ■-■ in Figure 2, Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2, Figure 5 is a cross-sectional view taken along line ■-■ in Figure 2, and Figure 6 is a cross-sectional view taken along line ■-■ in Figure 2. The figure is ■− in Figure 2.
7 is an explanatory diagram of the method of detecting the neutral angular position of the yoke assembly, Figures 8 and 9 are explanatory diagrams of the method of detecting the neutral position of the input shaft, and Figure 10 is a cross-sectional diagram along the line A schematic diagram showing the relationship with the rear wheel steering device, FIG. 11 is a sectional view taken along line S-8 in FIG. 10, and FIG. 12 shows the relationship between the displacement amount of the support and the displacement amount of the rear wheel steering shaft. It is a diagram. ... Rear wheel steering device ... Rear wheel steering shaft ... Power steering means ... Lever assembly (displacement transmission means) ...
... Hydraulic switching valve ... Output rod member ... Yoke assembly ... Input shaft

Claims (2)

[Claims] (1) A mechanical system that displaces a rear wheel steering shaft that steers the rear wheels includes an input shaft that inputs the amount of steering angle of the front wheels, an output rod member that receives input from the input shaft and strokes in the axial direction, and a yoke assembly that is linked to and swingably supported by the output rod member, and controls the stroke amount of the output rod member due to the rotation of the input shaft according to the swing angle of the yoke assembly; The power steering system is configured such that the stroke amount of the output rod member is transmitted to the rear wheel steering shaft by the means, and the hydraulic system that assists the displacement of the rear wheel steering shaft hydraulically assists the displacement of the rear wheel steering shaft. and a hydraulic switching valve for controlling the power steering means, the hydraulic switching valve is linked to the displacement transmitting means, and the mechanical system and the hydraulic system are connected, the vehicle rear wheel steering system comprising: The neutral adjustment of the mechanical system is carried out based on the operating state of A neutral adjustment method for a rear wheel steering system of a vehicle, which comprises adjusting the neutral position of the hydraulic system to absorb the deviation between the hydraulic system and the hydraulic system, and then assembling the hydraulic system and connecting the hydraulic system to a mechanical system. (2) When adjusting the neutral position of the mechanical system, detect the neutral angular position of the yoke assembly and the neutral angular position of the input shaft, and when connecting the hydraulic system to the mechanical system, set the rear wheel steering shaft to the neutral position. The neutral adjustment method for a vehicle rear wheel steering system according to claim 1, wherein the displacement transmitting means is fully assembled.