JPH0455169A - Standard position detecting method of rear wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To detect a neutral angle position (zero phase) as a standard position of a yoke assembly accurately and easily without trial and error by detecting a position of angle, to where a yoke assembly is rotated, as a neutral angle position of the yoke assembly. CONSTITUTION:A yoke assembly 18 is rotated from a stroke position of an output rod member 16 with a moving quantity delta1, putting a neutral angle position between the rotation, by a stroke displacement quantity (moving quantity -delta) of the output rod member 16. Next, an input shaft 26 is rotated by -thetato measure a moving quantity delta2 of the output rod member 16, and a position of angle, where the yoke assembly 18 is rotated by a stroke displacement quantity -delta2<2>/(delta1+delta2) of the output rod member 16 from that condition, is detected as a neutral angle position (zero phase) as a standard position of the yoke assembly 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reference position detection method for a vehicle rear wheel steering system.

(Prior Art) Conventionally, as described in, for example, Japanese Unexamined Patent Publication No. 1-273772, there has been an input shaft for inputting the amount of steering angle of the front wheels, and an input shaft that receives input from the input shaft and strokes in the axial direction. An output rod member that steers a rear wheel, and a yoke assembly that is linked to and swingably supported by the output rod member, and that controls the stroke displacement amount of the output rod member due to the rotation of the input shaft depending on the swing angle of the output rod member. Vehicle rear wheel steering devices are known.

In such a device, the stroke position of the output rod member and therefore the amount of rear wheel steering control are changed depending on the swing angle of the yoke assembly, so in order to accurately steer the rear wheels, Neutral angle position (zero phase), which is the reference position for the swing of the yoke assembly;
That is, it is necessary to accurately determine a position where the output rod member does not move even if the input shaft is rotated.

Conventionally, the yoke assembly was roughly swung around the neutral angular position in one study, and then the true neutral angular position (reference position), where the output rod member would not be stroked even if the input shaft was rotated, was determined through process and error. It was detected by

(Problem to be Solved by the Invention) However, if the neutral angular position of the yoke assembly is detected by trial and error in this way, there will be a trying error, and the time required to detect the true neutral angular position will increase. The current situation is that the length is long, making the work of detecting the neutral angular position of the yoke assembly cumbersome.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reference position detection method for a vehicle rear wheel steering device as described above, which can easily detect the neutral angular position (zero phase) of the yoke assembly. It is something to do.

(Means for Solving the Problems) The present invention 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 steers the rear wheels by stroking in the axial direction; a yoke assembly 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 changed depending on the swing angle of the yoke assembly. This is based on the assumption that the shaft and yoke assembly are set at a desired angular position, the input shaft is held in that state and rotated by a desired angle, and the rotation angle θ of the input shaft and the output rod member are calculated at that time. The amount of movement δ1 is measured, and the yoke assembly is rotated around the neutral angle position by the amount of movement of the output rod member −δ1 stroke from the stroke position of the amount of movement δ1 of the output rod member, and the input shaft is rotated by 1θ. , the amount of movement δ2 of the output rod member
is measured, and the angular position where the yoke assembly is rotated by the amount by which the output rod member is displaced by δ22/(δ1+62) is set as the neutral angular position of the yoke assembly.

(Function) Move the input shaft and yoke assembly to any desired angle position. In this state, the input shaft is held and rotated by an arbitrary angle, and the rotation angle θ of the input shaft and the amount of movement δ of the output rod member at that time are measured. Rotate the yoke assembly around the neutral angle position by the amount of movement of the output rod member -61 strokes from the stroke position of the movement amount δ1 of the output rod member, rotate the input shaft 10 times, and then rotate the input shaft 10 times to move the output rod member. δ2 is measured, and from that state the output rod member is adjusted to δ22/(
δ1+62) The angular position at which the yoke assembly is rotated by the amount of displacement is detected as the neutral angular position of the yoke assembly.

(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 schematically in FIG. 14 and a hydraulic switching valve] 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 amount of steering angle of the front wheels. It is configured to change the steering ratio according to the vehicle speed.

The rear wheel steering shaft 13 extends in the vehicle width direction, and has both ends connected to the left and right sides via a pair of left and right tie rods and knuckle arms.
It is connected to a pair of rear wheels, and the rear wheels are steered by stroke displacement of the rear wheel steering shaft 13 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 varies the steering ratio in the axial direction (vehicle width direction) according to the amount of steering angle of the front wheels (front wheel steering angle or steering wheel steering angle). It has an output rod member 16 that can be stroked.

Further, as will be described later, the ratio of the stroke displacement amount of the output rod member 16 to the steering angle amount of the front wheels (corresponding to the steering ratio) depends on the swing angle of the yoke assembly 18 that is swing-driven by the stepping motor 17. It is configured so that it changes depending on the situation. The amount of rotation of the stepping motor 17 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 detected by a steering ratio sensor (not shown). and is feedback-controlled by the detection signal.

The hydraulic switching valve 15 is controlled to switch according to the stroke displacement amount of the output rod member 16 in the steering ratio variable means 11, and the power steering means 12, which generates steering force using hydraulic pressure, steers the rear wheels. axis 1
3 displacements are hydraulically assisted.

Further, the steering ratio variable means 11 includes the output rod member 16
, stepping motor 17 and yoke assembly 18
(swing shaft member 22, pendulum arm 23, swing gear 31), it also includes a bevel gear 21 and a connecting rod 24, and these members 16, 17, 18, 21, 24,
As shown in detail in FIGS. 2 to 7, the casing 25
is housed in.

The output rod member 16 of the steering ratio variable means 11 is supported by the casing 25 so as to be able to make a stroke displacement in the axial direction, and by making a stroke displacement in the axial direction, the output rod member 16 transmits the displacement transmission means 14 as will be described later. The rear wheel steering shaft 13 is displaced in its axial direction (vehicle width direction) through the rear wheel steering shaft 13, thereby steering the rear wheels linked to both ends of the rear wheel steering shaft 3.

The bevel gear 21 is connected to the lever 2 of the output rod member 16.
8 on the output rod member 16 side, it is supported by the output rod member 16 via a cylindrical support member 52 so as to be rotatable together with the output rod member 16 and about an axis coaxial with the output rod member 16 . As the pinion 27 at the rear end of the input shaft 26, which meshes with the bevel gear 21 and inputs the amount of steering angle of the front wheels, rotates by steering the steering wheel, the bevel gear 21 rotates around the axis.

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 meshes with a worm 32 that rotates by driving the stepping motor 17, and rotates around the axis of a swing shaft 31a (see figure m4) that is perpendicular to the plane of the paper and intersects the axis Ω1 of the swing shaft member 22. As the swing gear 31 rotates, the swing shaft member 22 is also rotated at the same time. Note that the swing shaft 31a of the swing gear 31 is coupled to the motor shaft 17a of the stepping motor 17 via a coupling member 54 (see FIG. 6).

The pendulum arm 23 is connected to the swing shaft member 22 so as to be swingable about the axis 91 of the swing shaft member 22, and the axis fI2 of the pendulum arm 23 is the same as the rotation axis of the swing shaft portion 22. The connection position to the swing shaft member 22 is determined so as to pass through the intersection of the swing shaft member 22 with the axis Nl.

Like the rear wheel steering shaft 13, the connecting rod 24 has an axis parallel to the axis ρ3 of the output rod member 16,
The output rod member 16 is connected to the bevel gear 21 and the swing arm 23, respectively, so that the output rod member 16 and the yoke assembly 18 are linked. The connection to the output rod member 16 is made by splitting and coupling the intermediate part of the connection rod 24 to a lever 28 fixed to the end of the output rod member 16, and the connection to the bevel gear 21 is made by connecting the bevel gear 2 to the lever 28 fixed to the end of the output rod member 16. This is done by inserting one end of the connecting rod 24 into an insertion hole formed in the extension part 52a of the support part 52 to be removed.
The connection is made by inserting the pendulum arm 23 through an insertion hole of a ball joint member 33 provided at the other end of the connecting rod 22 so as to be rotatable in all directions.

), the connecting rod 24 is an output rod member]6
Although it is fixed to the bevel gear 2], it is capable of sliding in the direction of the axis ρ4, and
It is possible to slide in the direction of the axis Ω2 relative to the axis Ω2.

The axis Ω2 of the pendulum arm 23 is tilted with respect to the direction orthogonal to the axis ρ3 due to the rotation of the swing member 22, and the pendulum arm 23 slides in this tilted direction. Since the included angle change between Ω2 and the axis Ω4 is absorbed, the component of the force transmitted from the pendulum arm 23 to the connecting rod 24 in the direction orthogonal to the axis Ω3 of the output rod member 16 is absorbed at the connecting point, and The relative movement in the orthogonal direction becomes i+J.

In this way, the connection between the pendulum arm 23 (yoke assembly 18) and the connecting rod 24 in the steering 1 and 1J variable means 1 is made such that both parts can be moved relative to each other in the direction perpendicular to the axis Ω3. Therefore, when the pendulum arm 23 rotates, the locus of the pendulum arm 23, the connecting rod 24, and the connecting point becomes a circular locus or an elliptical locus on the outer circumferential surface of a cylinder with a predetermined radius centered on the axis Ω3.

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 perpendicular to the axis g3 of the output rod member 16, the axis Ω4 of the connecting rod 24 and the output rod member The angle between the output rod member 16 and the axis ρ3 can be made constant, and thereby it is possible to prevent a left-right deviation from occurring in the displacement of the output rod member 16.

Further, the output rod member 16 has one end connected to the connecting rod 24 via a lever 28, and the other end of the output rod 36, or the other end of the output rod 36 is fitted into a cylindrical rod kite 35 so as to be displaceable in the direction of the axis Ω3. The ends of the rod guide 35 and output rod 36 are supported by the casing 25.

The rod guide 35 has a first engaging portion 35a (see FIG. 5) that engages with the engaging end portion A of the displacement transmitting means 14.
The cylindrical part 35b and the second cylindrical member 35c screwed to the first cylindrical member 35b are nailed, and a spring 37 is inserted between the output rod 36 and the second cylindrical member 35c.
is interposed.

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 rod guide 35 via the spring 37, and from this rod guide 35 to the engaging portion 315a. The displacement is transmitted to the engaged end A of the engaged displacement transmitting means 14. However, if the movement of the engaging end A of the displacement transmitting means 14 is restricted and a load greater than the spring force of the spring 37 acts on the rod guide 35 when the output rod 36 is displaced, then the output rod 36 The displacement is absorbed by the contraction of the spring 37 and is not transmitted to the rod guide 35 and therefore to the displacement transmitting means 14.

Further, the hydraulic switching valve 15 is connected to the valve housing 4.
), and a valve spool 42 accommodated in the valve housing 41 so as to be displaceable with respect to the valve housing 4 in the direction of an axis β5 parallel to the axis Ω3 of the output rod member 16.

This valve spool 42 is connected to the output rod member 16 and the rear wheel steering shaft via a displacement transmission means 14, which will be described in detail below.
Displaced by The supply of hydraulic pressure to the power steering means 12 is controlled by this displacement of the valve spool 42.

A centering spring 45 is provided on the rear wheel steering shaft 13, and when the hydraulic pressure in the hydraulic switching valve 15 or the power steering means 12 disappears, the rear wheel steering device 1
If damage or failure occurs in the mechanical system and the hydraulic system is drained and the hydraulic pressure in the cylinder of the power steering means 12 disappears, the spring force of the centering spring 45 causes the rear wheel steering shaft 13 to be neutralized. The vehicle is positioned at a position where the rear wheels are not steered and are traveling straight, so as to provide a so-called fail-safe system.

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 provided directly on the rear wheel steering shaft 13.
Left and right oil chambers 44 and 4B 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 the displacement of the rear wheel steering shaft 13 caused by the displacement of the valve spool 42 causes the valve spool 42 to move in a predetermined direction.
It is constructed so that it can be operated in a direction to displace it in the opposite direction to the above.

Specifically, the displacement transmitting means 14 has a cross lever 14a consisting of a vertical lever and a horizontal lever, and the engaging end A, which is one end of the vertical lever, is connected to the engaging part 35a of the rod guide 35, and the other end is connected to the engaging part 35a of the rod guide 35. The engaging end B, which is the end, is connected to the rear wheel steering shaft 13, and
An engaging end C, which is one end of the horizontal lever, is engaged with a support support 38 fixedly attached to the vehicle body, and an engaging end, which is the other end, is engaged with the valve spool 42. The engaging end portions A, B, and D are immovable in the axial direction with respect to the engaging portion 35a1 of the rod guide 35, the rear wheel steering shaft 13, and the valve sprue 42, but are movable in other directions and rotated. The engaging ends C are rotatably but immovably engaged by a ball joint (not shown).

Therefore, if the output rod member 16 is displaced to the right from a state where the valve spool 42 and the rear wheel steering shaft 13 are both in the neutral position, the engagement end A of the cross lever 14a will move to the right along with the output rod member 16. When the engagement end A is displaced, tire reaction force and reaction force from the centering spring 45 are acting on the rear wheel steering shaft 13, so this engagement end B is immobile in the axial direction, and Since the engaging end C is also fixedly attached to the support member 1-38 (body 11j) and is immovable, the cross lever 14a is tilted about the straight line connecting the engaging ends B and C. In other words, the cross lever 14a is operated in a direction to displace the valve spool 42 in a predetermined direction, that is, rightward, and the engaging end portion displaces the valve spool 42 in the rightward direction.

When the valve spool 42 is displaced rightward from the neutral position in this way, the oil pressure in the oil 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 13 to the left. The hydraulic pressure that pushes the rear wheel steering shaft 13 leftward increases in accordance with the increase in rightward displacement of the valve spool 42, and the balance position is reached.

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 balance with the reaction force).

When the valve spool 42 is further displaced to the right from this state, the hydraulic pressure generated in the power steering means 12 becomes larger than the external force acting on the rear wheel steering shaft 13, and the rear wheel steering shaft 13 is moved to the right. It is displaced to the left by 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 is immobile, and the engaging end C is also displaced. 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 3 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 returns to the balance position. By stopping -C4-;- and repeating this operation, the output rod member 16
The rear wheel steering shaft 1'3 is displaced by an amount corresponding to the amount of displacement,
The rear wheels will be steered according to the amount of displacement.

2. When the output rod member 16 is displaced to the left, the movements of the cross lever 14a1, the valve spool 42, and the rear wheel steering shaft 13 are simply reversed from the above case, and the operating principle is the same, so the explanation will be omitted. Omitted. The movement of the valve spool 42 is described in the prior art (Japanese Unexamined Patent Publication No. 1999-1-1).
273772).

The steering ratio changing control by the steering ratio variable means 11 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, FIGS. 7 to 9 show a method for detecting the neutral position of the yoke assembly 18 (specifically, the swing gear 31), which affects the accuracy of the controlled steering amount of the rear wheels in the rear wheel steering system described above. I will explain along. Note that this is performed in a state in which the support support 38 is temporarily fixed, the cover 53 is not yet attached to the casing 25, and the hydraulic pressure is not applied.

First, the input shaft 26 is fixed at an arbitrary angular position other than the neutral angular position, and the yoke assembly] 8 is fixed at an arbitrary angular position other than the neutral angular position (see FIG. 7). A displacement meter 51 is applied to the end of the output rod member 16, so that the amount of movement of the output rod member 16 can be detected.

Then, the input shaft 26 is rotated by an arbitrary angle from the neutral angular position, and the rotation angle θ of the input shaft 26 and the movement amount δ1 of the output rod member 16 at that time are measured (see FIG. 8) and stored.

Thus, the yoke assembly 18 is rotated from the neutral angular position by the displacement of the output rod member 16 by a stroke of -δ1.

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

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

The reason why the true neutral angular position (zero phase) of the yoke assembly 8 can be obtained by the above equation -62'/(δ1+δ2) is as follows (see FIG. 9).

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

δL = A (tanφQ+jan(φ−φ0)l(1
) δ2 = A (tanφo+tan(φ−φ0)l(
2) From equations (1) and (21), δ1/δ2-A/B (3) Moreover, δ2 can also be expressed as follows.

δ2=AtanφO+Btanφ0 ,', tanφ0=62/(A×B) (
4) Multiplying both sides of equation (4) by B, B tanφ0=δ2-B/ (A+B)=62/
(A/B +1) (5) Expression (3) becomes Expression (5)
Substituting into , B tanφ0=δ2/(δ1/δ2+1)=δ22/
(δ1+62) After the neutral angle position of the above yoke assembly [8] is detected, the support support 38 is temporarily assembled so that it can be displaced, and with hydraulic pressure applied, even if the support support 38 is displaced, the rear wheel steering axis The neutral position of the rear wheel steering shaft 13 in which the rear wheel steering shaft 13 is not displaced is detected, and the support support 38 is set in a wooden frame (=J-keshi, neutral position between the mechanical system and the hydraulic system) while the rear wheel steering shaft 13 is held at the neutral position. The displacement of the assembly of the support support 38 is absorbed by adjusting the position, and the rear wheel steering device 1 is adjusted to neutral.

(Effects of the Invention) As described above, the present invention sets the input shaft and yoke assembly at an arbitrary angular position, and in that state rotates the input shaft at an arbitrary angle around the neutral angular position. The rotation angle θ of the input shaft and the movement amount δ1 of the output rod member are measured, and the output rod part profit is the movement amount −61 from the stroke position of the movement amount δ1 of the output rod member.
Rotate the yoke assembly around the neutral angle position by the stroke, rotate the input shaft by 1θ, measure the amount of movement δ2 of the output rod part, and from that state, calculate the displacement of the output rod member by δ22/(δ1+62). Since the angular position obtained by rotating the yoke assembly as much as possible is set as the neutral angular position of the yoke assembly, the neutral angular position (zero phase), which is the reference position of the yoke assembly, can be detected accurately without trial and error. It can be done quickly and easily.

[Brief explanation of drawings]

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 shows Vl in Figure 2.
-Vl line sectional views, FIGS. 7 and 8 are explanatory diagrams of a method for detecting the neutral angular position of the yoke assembly, and FIG. 9 is an explanatory diagram of the principle of detecting the neutral angular position of the yoke assembly. 1... Rear wheel steering device 16... Output rod member 18... Yoke assembly 26... Input shaft

Claims (1)

[Claims] (1) 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 steers the rear wheels by stroking in the axial direction, and is linked to the output rod member and can swing. A vehicle rear wheel steering device comprising a yoke assembly supported by the yoke assembly, and in which the stroke amount of the output rod member due to the rotation of the input shaft is changed depending on the swing angle of the yoke assembly. Set the input shaft to the angular position, and in that state, rotate the input shaft any desired angle around the neutral angular position, and calculate the rotation angle θ of the input shaft at that time.
and the movement amount δ1 of the output rod member is measured, and the yoke assembly is rotated around the neutral angle position by the amount of movement −δ1 stroke of the output rod member from the stroke position of the movement amount δ1 of the output rod portion +A, and the input shaft The amount of movement δ2 of the output rod member is measured by rotating the output rod member by -θ, and from that state, the angular position where the yoke assembly is rotated by the amount that the output rod member is displaced by -δ2^2/(δ1+δ2) is the neutral position of the yoke assembly. A reference position detection method for a vehicle rear wheel steering device, characterized in that the reference position is determined as an angular position.