JP2001180244A - Vehicle attitude control device - Google Patents

Abstract

(57) [Summary] [Problem] Unpleasant vehicle behavior in low frequency range such as sudden steering, sudden start, and sudden braking without deteriorating ride comfort in high frequency range such as when driving on a general road. Suppress. SOLUTION: An actuator 6 installed between a unsprung member and a sprung member 24 of each wheel, a controller for outputting attitude control information based on a sensor information signal, and an attitude control information input from the controller are provided. A drive circuit that outputs an operation signal to each actuator. The actuator includes a cylinder 20 having hydraulic oil sealed therein and a lower end connected to a suspension member, a piston 22 partitioning the inside of the cylinder into a piston upper chamber 21a and a piston lower chamber 21b, and a lower end connected to the piston 22 and an upper end connected to the piston 22. The vehicle includes a piston rod 26 having a variable rod length connected to the vehicle body side member side, and an electric motor 28 for rotating a part of the piston rod based on an operation signal from a drive circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle attitude control device for controlling a vehicle attitude by operating an actuator provided between an unsprung member and a sprung member.

[0002]

2. Description of the Related Art As a vehicle attitude control device, an actuator provided between an unsprung member and a sprung member of a wheel is operated to generate a relative displacement between the unsprung member and the sprung member, thereby controlling the vehicle posture. Devices are known that perform this. As this type of technology, there is, for example, Japanese Patent Application Laid-Open No. 5-85131 (hereinafter referred to as conventional technology).

This prior art is a suspension device provided with an actuator coaxially with a coil spring.
The actuator is a double-rod double-acting cylinder in which a piston connected to an intermediate portion of a piston rod is arranged in a cylinder, and the cylinder filled with hydraulic oil by the piston is partitioned into a first oil chamber and a second oil chamber. The upper end of the piston rod is connected to the vehicle body, the rack & pinion mechanism is connected to the lower end of the piston rod, and the housing incorporating the rack & pinion mechanism is connected to the axle side. This is a device for controlling the vehicle height by moving the piston rod of the actuator up and down with respect to the axle side.

[0004]

However, in the prior art, since the actuator is incorporated in parallel (coaxial) with the coil spring, the sensitivity to vibration input from the road surface is increased, and the riding comfort particularly in a high frequency region. There is a problem that is worse. Further, the structure in which the rack and pinion mechanism is connected to the lower end of the piston rod becomes a large-sized device, and the degree of freedom of the vehicle layout is greatly restricted.

The present invention has been made in view of the above circumstances, and does not degrade the ride comfort in a high frequency range such as when driving on a general road, and reduces the driving speed during sudden steering, sudden starting, and sudden braking. It is an object of the present invention to provide a vehicle attitude control device capable of suppressing unpleasant vehicle behavior in a frequency range and further improving durability, reducing size and weight, and reducing cost.

[0006]

According to a first aspect of the present invention, there is provided an actuator arranged between a sprung member and a sprung member of each wheel based on sensor information for detecting a vehicle state. In the vehicle attitude control device for controlling the vehicle attitude by operating the cylinder, the actuator comprises: a cylinder filled with hydraulic oil connected to one of the unsprung member and the sprung member; and one fluid in the cylinder. A piston that partitions the chamber and the other fluid chamber and slides in the cylinder; one end connected to the piston, and the other end connected to the other of the unsprung member and the sprung member; And a piston rod control means for changing the rod length of the piston rod based on the sensor information.

According to a second aspect of the present invention, in the vehicle attitude control device according to the first aspect, the piston rod includes:
A plurality of rod members are connected in series via a feed screw mechanism, and the rod length is changed by relatively displacing each rod member in the axial direction by operating the feed screw mechanism under the control of the piston rod control means. I made it. According to a third aspect of the present invention, in the vehicle attitude control apparatus according to the second aspect, the piston rod is formed with a female screw on an inner peripheral surface, and the piston is connected to one end of the piston rod to restrict rotation. A hollow cylindrical first rod member that slides in the cylinder axis direction in the cylinder, and a male screw member inserted coaxially from the other end of the first rod member and screwed to the female screw at one end. A second cylindrical member having a solid cylindrical shape having the other end connected to the other of the unsprung member and the sprung member, and wherein the second rod member is controlled by the piston rod control means. When a predetermined forward and reverse rotational force is transmitted to the female screw, the rotational force is transmitted to the female screw via the male screw, and the rotation of the first rod member is restrained. Of the second rod member It was to be converted as a linear motion of the cylinder axis.

According to a fourth aspect of the present invention, in the vehicle attitude control apparatus according to the second aspect, the piston rod is provided with one end formed with a female screw on the inner peripheral surface and a male screw on the outer peripheral surface in the cylinder. And a hollow cylindrical first rod member that slides in the cylinder axis direction while being restrained from rotating by being inserted into the cylinder, and the unsprung member and the spring that are inserted into the first rod member at one end. A second rod member connected to the other of the upper members and having a male screw member fixed to the other end thereof and screwing the male screw member to the female screw of the first rod member; and a second rod penetrating the male screw member. A third rod member that is inserted into a shaft hole formed on the other end side of the member and is movable in the cylinder axis direction while rotation is restricted, and a hollow cylindrical member having a piston connected to an end thereof; 3 rod part And a fourth rod member whose inner end is coaxially fixed to the inner bottom portion and a female screw formed on the inner periphery is screwed to the male screw of the first rod member. The second
When a predetermined forward and reverse rotational force is transmitted to the rod member, the rotational force is transmitted to the female screw via the male screw, and the rotation of the first rod member is restrained.
The rotational force is converted as a linear motion in a cylinder axial direction in a direction in which the second rod member and the fourth rod member are separated from each other or in a direction in which the second rod member and the fourth rod member are close to each other. I made it.

According to a fifth aspect of the present invention, in the vehicle attitude control device according to the third or fourth aspect, the threaded portion of the male thread member of the second rod member and the female thread of the first rod member is positioned. The internal space of the first rod member and one of the fluid chambers in the cylinder where the first and second rod members do not extend communicate with each other through a communication hole.

According to a sixth aspect of the present invention, in the vehicle attitude control device according to the third or fourth aspect, the threaded portion of the male screw member of the second rod member and the female screw of the first rod member is positioned. The internal space of the first rod member and the other fluid chamber in the cylinder, which is the outer peripheral space of the first rod member, communicate with each other through a communication hole.

[0011] Further, the invention according to claim 7 is based on claim 1.
In the vehicle attitude control device described in the above, the piston rod control means is configured to include a hydraulic control unit capable of changing the volume of an oil chamber, and the piston rod has a through hole at an axial center position in the cylinder. A first rod member inserted into the first rod member and a second rod connected to the one end of the first rod member so as to be slidable while maintaining liquid tightness and connected to the piston.
A rod member and a tube communicating between a through hole of the first rod member and an oil chamber of a hydraulic control unit, wherein the tube, the through hole, and the Hydraulic oil is filled up to the internal space of the second rod member defined by the one rod member.

[0012]

According to the first aspect of the present invention, the characteristic of the ordinary passive damping force generated according to the relative speed of the piston sliding in the cylinder is not affected, but is based on the sensor information. The length of the piston rod is changed by the control of the piston rod control means, and the change in the attitude of the vehicle body is suppressed by the generation of an active damping force due to the rod expansion and contraction speed generated at that time. Unpleasant vehicle behavior in a low-frequency range, such as sudden steering, sudden start, and sudden braking, can be suppressed without deteriorating ride comfort in a high-frequency range as in the case of time.

According to the second aspect of the present invention, since the rod length of the piston rod is changed by using a feed screw mechanism having a simple structure, a low-cost apparatus can be provided. According to the third and fourth aspects of the present invention, a plurality of rod members are arranged coaxially with each other, and one of the rod members is inserted into the other to form a piston rod.
It is possible to provide a compact device in which the degree of freedom in vehicle layout is greatly improved.

In particular, according to the fourth aspect of the present invention, the second
Since both the rod member and the fourth rod member are linearly moved in the cylinder axis direction to increase the amount of change in the rod length, it is possible to provide a posture control device with high control response. According to the invention as set forth in claim 5, when the piston rod expands and contracts, hydraulic oil enters the internal space of the first rod member from one of the fluid chambers in the cylinder, and the pressure of the hydraulic oil is reduced by the second rod member. It acts so that the rotational friction of the threaded portion of the male screw member of the member and the female screw of the first rod member is reduced. For this reason, the rotation control force of the piston rod control means for rotating the second rod member can be reduced.

According to the present invention, when the piston rod is extended, the hydraulic fluid enters the internal space of the first rod member from the other fluid chamber in the cylinder, which is the outer peripheral space of the first rod member. And the pressure of the hydraulic oil acts to reduce the rotational friction of the threaded portion of the male screw member of the second rod member and the female screw of the first rod member. For this reason, the rotation control force of the piston rod control means for rotating the second rod member can be reduced.

Further, according to the present invention, since the piston rod control means can set a hydraulic control unit using an oil pressure that generates a large control force at an arbitrary position, the degree of freedom in vehicle layout is greatly increased. Can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle attitude control device according to the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a vehicle, and reference numerals 2FL to 2R in the drawing.
R indicates a front left wheel to a rear right wheel, and reference numeral 4 indicates an attitude control device.

The attitude control device 4 includes an actuator 6 installed between the unsprung member and the sprung member of each wheel 2FL to 2RR, a steering angle sensor 8, a vehicle height sensor 10, a lateral acceleration sensor 12, and a vertical acceleration sensor. 13 and longitudinal acceleration sensor 1
A controller 16 for detecting a vehicle state based on a signal detected from the controller 4 and outputting attitude control information; and a drive circuit 18 for outputting an operation signal to each actuator 6 based on the attitude control information input from the controller 16. ing.

The actuator 6 is, as shown in FIG.
A cylinder 20 having a lower end connected to the suspension member with hydraulic oil sealed therein, a piston 22 partitioning the interior of the cylinder 20 into a piston upper chamber 21a and a piston lower chamber 21b, and a lower end connected to the piston 22; A piston rod 26 having an upper end connected to the vehicle body side member 24 and having a variable length, an electric motor 28 for rotating a part of the piston rod 26 based on an operation signal sent from the drive circuit 18; It has.

The cylinder 20 includes a base shell 20a,
A reservoir oil chamber 20b is provided between the base shell 20a and a tube 20c inserted therein. A piston 22 slides in the tube 20c. Here, although not shown, the piston 22 has a built-in piston valve that generates a damping force in the process of extending the piston rod 26, and the bottom of the tube 20c generates a damping force in the process of contracting the piston rod 26. A base valve 30 is provided. Then, a working oil having a volume corresponding to the entry and exit of the piston rod 26 enters and exits the reservoir oil chamber 20b via the base valve 30. Air in the atmosphere is contained in the reservoir oil chamber, and this compresses and expands to absorb the volume of hydraulic oil flowing in and out.

The piston rod 26 has an internal thread 3
2a, and a hollow cylindrical first rod member 32 having a piston 22 connected to the lower end thereof;
Is inserted coaxially from the upper end of the male screw member 34a at the lower end.
And a solid cylindrical second rod member 34 connected to the second rod member 34. A cylinder cap 3 slidably supports the first rod member 32 while maintaining fluid tightness through an annular oil seal 36 at the upper end of the cylinder 20.
8 is mounted, and a rod cap 42 for slidably supporting the second rod member 34 while maintaining liquid tightness is also mounted on the upper end of the first rod member 32 via an annular oil seal 40. Have been.

Here, the oil seal 36 is supported by an annular detent member 44 which is pressed into the cylinder cap 38. As shown in FIG. 3, a ridge 4 fitted in a vertical groove 32c formed along the axial direction of the outer periphery of the first rod member 32 is formed on the inner peripheral surface of the rotation preventing member 44.
4a, whereby the first rod member 3
In No. 2, rotation is restricted by the rotation preventing member 44 and only movement in the axial direction is allowed.

The piston 22 and the first rod member 3
At the lower end of 2, a communication hole 46 that communicates the internal space 32 b of the first rod member 32 with the lower piston chamber 21 b is provided. On the other hand, the upper part of the second rod member 34 is moved in the axial direction with respect to the vehicle body side member 24 by the bearings 48, 50, 52 and the elastic member 54 provided on the motor support portion 35 provided on the vehicle body side member 24. , The movement in the direction perpendicular to the axis is restricted, only the rotation around the axis is allowed and supported, and the upper end of the second rod member 34 is provided with the electric motor 2.
8, the output shaft 28a facing in the vertical direction is coaxially connected. That is, the disk member 56 is fixed to the upper outer periphery of the second rod member 34, and the bearings 48 and 50 are disposed so as to be in contact with the upper and lower parts of the disk member 56, and the shaft of the second rod member 34 is Bearing 52 so as to contact the outer periphery of the upper end of the second rod member 34.
The movement of the second rod member 34 in the direction perpendicular to the axis is restricted.

The controller 16 includes a microcomputer (not shown) including an input detection device, an arithmetic processing device, a storage circuit for storing a control program executed by the arithmetic processing device and an operation result, and an output circuit. In the arithmetic processing device, a control value for stabilizing the vehicle attitude is determined based on signals detected by the steering angle sensor 8, the vehicle height sensor 10, the lateral acceleration sensor 12, the vertical acceleration sensor 13, and the longitudinal acceleration sensor 14. Then, a control signal corresponding to the control value is output to the drive circuit 18. Then, the drive circuit 18 outputs a control current to the electric motor 28 constituting the actuator 6 of each of the wheels 2FL to 2RR.

The actuator 6 having the above structure is
When the second rod member 34 rotates in the normal rotation direction by the forward rotation of the electric motor 28, the first rod member 32 in which the female screw 32a is screwed to the male screw member 34a of the second rod member 34 is to be rotated. However, the first rod member 32
Is prevented from rotating by the detent member 44,
Only the rod member 34 moves upward by a predetermined amount while rotating. That is, when the electric motor 28 is driven to rotate forward, a female screw 32 a formed on the inner peripheral surface of the first rod member 32
Male screw member 34a connected to the lower end of second rod member 34
(Hereinafter referred to as feed screw mechanism)
Operates to extend the rod length of the piston rod 26.

When the second rod member 34 rotates in the reverse direction by the reverse rotation of the electric motor 28, the feed screw mechanism operates in the reverse direction, and the second rod member 34 moves downward by a predetermined amount while rotating. The rod length of the piston rod 26 is reduced. Here, the normal passive damping force generation mechanism by the piston valve of the actuator 6 and the base valve 30 is as follows. When the piston rod 26 is extended by the lifting of the vehicle body, the piston upper chamber 21a is pressurized and the hydraulic oil is increased. Flows into the lower piston chamber 21b while generating a damping force by the piston valve. At this time, the piston rod 2
Hydraulic oil corresponding to the retreat of 6 is insufficient in the lower piston chamber 21b, but this shortage is replenished by the hydraulic oil in the reservoir oil chamber 20b pushing the base valve 30 open and flowing with almost no resistance. On the other hand, when the piston rod 26 performs the contracting process due to the sinking of the vehicle body, the piston lower chamber 2
The hydraulic oil 1b flows into the upper piston chamber 21a with little resistance, but at the same time, the lower piston chamber 21b is pressurized by the penetration of the piston rod 26. The pressurized hydraulic oil pushes open the base valve 30 and flows into the reservoir oil chamber 20b while generating a damping force.

In this embodiment, in addition to the normal damping force described above, an active damping force is generated by the relative speed (rod expansion / contraction speed) of the piston rod 26 generated when the feed screw mechanism operates. That is, FIG. 4 shows a dynamic model of the actuator 6 of the present embodiment in which a new damping element including a feed screw mechanism is added in series with a normal damping element. The damping force F generated by the actuator 6 of the present embodiment is:

[0028]

(Equation 1)

The first term on the right side is the damping force generated by the normal damping element, and the second term on the right side is the active damping force generated at the rod stretching speed. As described above, in the present embodiment, when the controller 16 drives the electric motor 28 of the actuator 6 based on the detection value detected by each sensor, an active damping force is generated by the operation of the feed screw mechanism, and the state of the vehicle is changed. , An optimal damping force F is generated.

That is, the state of the active damping force generated by the feed screw mechanism will be described by describing the specific state of the vehicle. For example, when the vehicle turns a corner, the inertia of the vehicle to roll the vehicle body The force is detected by the sensor, and the controller 16 controls the outer ring-side actuator 6 based on the detected value.
Is output to the drive circuit 18 such that the electric motor 28 drives forward and the electric motor 28 of the inner-wheel-side actuator 6 drives reverse.

The outer ring-side actuator 6 driven forward by the electric motor 28 generates an active damping force due to the rod expansion / contraction speed of the feed screw mechanism that operates to extend the rod length of the piston rod 26. The force becomes a reaction force when the vehicle body on the outer wheel side sinks and suppresses a change in posture. Also, the actuator 6 on the inner wheel side in which the electric motor 28 is driven in reverse rotation under the control of the controller 16.
Generates an active damping force due to the rod expansion and contraction speed of the feed screw mechanism that operates to shorten the rod length of the piston rod 26, and this damping force is generated by the reaction force when the vehicle body on the inner ring side is going to float. To suppress posture changes. As described above, at the time of corner turning, the controller 16 controls each actuator 6 to generate an active damping force due to the rod expansion and contraction speed of the feed screw mechanism, thereby canceling the inertia force with respect to the vehicle body and preventing the vehicle from rolling. Perform control.

When the vehicle is braked, the sensor detects an inertia force for pitching the vehicle body. The controller 16 drives the electric motor 28 of the actuator 6 of the front wheel based on the detected value. And
The electric motor 28 of the actuator 6 on the rear wheel is driven in reverse. As a result, the front wheel actuator 6 generates an active damping force due to the rod expansion and contraction speed of the feed screw mechanism that operates to extend the rod length of the piston rod 26, and this damping force causes the front body to sink. It becomes a reaction force when trying to enter, and suppresses a change in posture. The actuator 6 of the rear wheel generates an active damping force by the rod expansion and contraction speed of the feed screw mechanism that operates to shorten the rod length of the piston rod 26, and this damping force causes the rear vehicle body to float. It becomes a reaction force when trying to go up and suppresses a change in posture. Thus, the attitude control of the vehicle that suppresses the nose dive by canceling the inertial force on the vehicle body is performed. In addition, at the time of starting, since the inertial force acts on the opposite side, the control opposite to the above-described control is performed.

When the vehicle travels on a rough road or the like, the vehicle body bounces in the vertical direction due to an input from the road surface. The sensor detects the absolute speed of the vehicle body in the vertical direction. Then, a control signal is output to the drive circuit 18 such that the electric motor 28 of the actuator 6 of each wheel is driven to rotate forward or reverse. As a result, the actuator 6 of each wheel generates an active damping force due to the rod expansion / contraction speed of the feed screw mechanism that attempts to extend or contract the rod length of the piston rod 26, and the vehicle body bounces in the vertical direction. Is performed to control the vehicle attitude.

Therefore, the attitude control device 4 of the present embodiment
Has the following effects. First, firstly, the attitude control device 4 of the present embodiment includes the wheels 2FL to 2R
R does not affect the characteristics of the normal passive damping force generated by the actuator 6 (damping characteristics generated by the piston valve and the base valve 30), and changes the rod length of the piston rod 26 of each actuator 6; The active damping force generated by the rod expansion and contraction speed of the feed screw mechanism generated at this time suppresses changes in the posture of the vehicle body, deteriorating ride comfort in high-frequency ranges such as when driving on ordinary roads. Unpleasant vehicle behavior in a low-frequency range, such as at the time of sudden steering, sudden start, and sudden braking, can be suppressed.

Second, the piston rod 26 is composed of a hollow cylindrical first rod member 32 and a second rod member 34 inserted in the first rod member 32. Since the rod length is changed by the relative displacement of the second rod members 23 and 34 in the axial direction, it is possible to provide a compact device in which the degree of freedom of the vehicle layout is greatly improved.

Third, only the second rod member 34 rotates, and the first rod member 32 disposed on the outer periphery of the first rod member 32 moves in the cylinder 20 in the axial direction without rotating. Therefore, the durability of the oil seal 36 disposed at the upper end of the cylinder 20 can be improved.
Fourth, by providing the communication hole 46 that communicates the internal space 32b of the first rod member 32 with the lower piston chamber 21b, the rotational friction of the feed screw mechanism can be reduced.

That is, referring to the model diagram of FIG. 5, if the communication hole 46 is not formed, an external force F ₁ is applied to the feed screw mechanism from the first rod member 32 side. The external force F ₁ is represented by _{F 1 = P 1 × S 1} -P 2 × S 2 ......... (2). Here, the pressure of P ₁ is the piston upper chamber 21a side, P ₂ is the piston lower chamber 21b, S ₁ is the piston lower chamber 2
Pressure receiving area of 1b, S ₂ is the pressure receiving area of the piston upper chamber 21a.

Here, as in the present embodiment, the communication holes 46
When forming the external force F ₂ of opposite direction exerted to the external force F ₁ from the male screw member 34a side to the feed screw mechanism. This external force F ₂ is represented by F ₂ = P ₁ × S ₃ (3), where S ₃ is the hole area of the communication hole 46.

Accordingly, the external force F ₃ applied to the feed screw mechanism of the present embodiment is as follows: F ₃ = F ₁ −F ₂ (4), and the external force F ₂ generated by forming the communication hole 46 is External force applied to the mechanism has been reduced. Thereby, the rotational friction of the feed screw mechanism can be reduced.

Here, when the hole area S ₃ of the communication hole is made as close as possible to the area of the internal space 32b, the external force F
₂ is generated, and the rotational friction of the feed screw mechanism can be greatly reduced. Fifth, since the rotational friction of the feed screw mechanism can be reduced, even if a small electric motor 28 is used, the feed screw mechanism can be reliably operated to control the attitude of the vehicle. Therefore, it is possible to provide the energy-saving attitude control device 4 with low power consumption, and it is possible to reduce the cost and size and weight of the device.

Next, FIGS. 6 and 7 show a second embodiment of the actuator 6 constituting the attitude control device 4. FIG. The same components as those in the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof will be omitted. The actuator 6 of the present embodiment includes an inner space 3 of the first rod member 32 at the lower end of the first rod member 32.
A communication hole 60 for communicating the piston 2b with the upper piston chamber 21a is provided.

The operation of the actuator 6 of this embodiment will be described with reference to a model diagram of FIG. When the downward force F ₄ is acting on the piston rod 26 to sink the vehicle body, the actuator 6 operates to extend the rod length of the piston rod 26, that is, the feed screw mechanism (the female screw 32 a of the first rod member 32). and performs an operation to continue to move upward (arrow a ₁ direction) while the second rod member 34 by the operation of the male screw member 34a) of the second rod member 34 is rotated. At this time, since the volume of the internal space 32b increases by the amount of the second rod member 34 withdrawing, the hydraulic oil is sucked into the internal space 32b from the upper piston chamber 21a through the communication hole 60. At this time, the pressure in the piston chamber 21a is reduced, to reduce the volume until the pressure in the piston chamber 21a and the piston lower chamber 21b is balanced, the cylinder 20 moves downwards (arrow A ₂ direction) .

Since the communication hole 60 is provided at the lower end of the first rod member 32, the force for lowering the cylinder 20 to the piston rod 26 acts on the lower end of the first rod member 32. The torque can be efficiently converted into a vertical motion. Next, FIG. 8 shows a third embodiment of the actuator 6 constituting the attitude control device 4. The same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The piston rod 66 of the actuator 6
Is a hollow cylindrical first rod member 68 formed into the cylinder 20 by forming a female screw 68a on the inner peripheral surface and a male screw 68b on the lower outer periphery, and an electric motor (shown in FIG. A second rod member 70 which is coaxially connected to the output shaft of the second rod member 28, a male screw member 70a is fixed to the lower end, and the male screw member 70a is screwed to the female screw 68a of the first rod member 68; A third rod member 72, which penetrates through 70a and is inserted into a shaft hole 70b formed on the lower end side of the second rod 70 and is movable in the vertical direction while rotation is restricted, and a piston 22 is connected to the lower end. The lower end of the third rod member 72 is coaxially fixed to the inner bottom, and the female screw 74a formed on the inner periphery is a hollow cylindrical member.
and a fourth rod member 74 screwed to the second rod member b.

A spline 72a is formed on the outer periphery of the upper part of the third rod member 72, and also engages with the spline 72a at the axial position of the male screw member 70a fixed to the lower end of the second rod member 70. A spline (not shown) is formed, and the third rod member 72
The rotational force is transmitted from the second rod member 70 via the male screw member 70a.

The third rod member 72 is fixed to the fourth rod member 74 via a disk-shaped fixing member 76. The fixing member 76 has an internal space 68c of the first rod member 68. A communication hole 76a is formed to communicate the piston and the lower piston chamber 21b with the communication hole 46. Here, the screw directions of the male screw 68b formed on the outer circumference of the first rod member 68 and the female screw 74a formed on the inner circumference of the fourth rod member 74 are different in the rotation direction in which the second rod member 70 moves upward. The fourth rod member 74 is configured to move downward and the second rod member 70 is configured to move upward in the rotation direction in which the second rod member 70 moves downward.

When the second rod member 70 rotates in the normal rotation direction by the forward rotation of the electric motor 28, the male screw member 7 of the second rod member 70
The first rod member 68 in which the female screw 68a is screwed into the first rod member 68
However, since the first rod member 68 is prevented from rotating by the rotation preventing member 44, the second rod member 70 moves upward while rotating. When the second rod member 70 moves upward while rotating as described above, the fourth rod member 74 also moves downward by a predetermined amount. As described above, when the electric motor 28 is driven to rotate forward, the second rod member 70 moves upward, and the fourth rod member 74 moves downward, and the rod length of the piston rod 66 extends in a two-stage manner.

When the electric motor 28 is driven to rotate in the reverse direction, the second rod member 70 moves downward while rotating, and the second rod member 70 moves downward while rotating,
The fourth rod member 74 also moves upward by a predetermined amount.
Thus, when the electric motor 28 is driven to rotate in the reverse direction, the second rod member 34 moves downward and the fourth rod member 74
Moves upward, and the rod length of the piston rod 66 is reduced in a two-stage manner.

When the rod length of the piston rod 66 is extended or shortened in two steps, the female screw 68a of the first rod member 68 and the male screw member 70a connected to the second rod member 70 are screwed together. (Hereinafter referred to as a first feed screw mechanism) and a portion where the male screw 68b of the first rod member 68 and the female screw 74a of the fourth rod member 74 are screwed together (hereinafter referred to as a second feed screw mechanism). ), The active damping force is generated by the relative speed of the piston rod 66 (rod expansion / contraction speed) generated during the operation of the piston rod 66.

Therefore, the posture control device 4 of the present embodiment
According to this, the characteristic of the normal passive damping force generated by the actuator 6 of each wheel 2FL-2RR (damping characteristic generated by the piston valve and the base valve 30) is not affected, and is provided on each wheel 2FL-2RR. A control signal is output to each of the electric motors 28 of the actuators 6, and the rod length of the piston rod 66 of each actuator 6 is expanded and contracted in two steps by the rotational force of the electric motor 28,
The active damping force generated by the rod expansion and contraction speed of the feed screw mechanism generated at this time suppresses changes in the posture of the vehicle body, deteriorating ride comfort in high-frequency ranges such as when driving on ordinary roads. Steer, sudden start,
Unpleasant vehicle behavior in a low frequency range, such as during sudden braking, can also be suppressed.

Further, the piston rod 66 has first to fourth
It is possible to provide a compact device in which the rod members 68, 70, 72, 74 expand and contract, and the degree of freedom of the vehicle layout is greatly improved. When the rod length of the piston rod 66 is extended or shortened in two steps, active damping force is simultaneously generated in the first feed screw mechanism and the second feed screw mechanism. A high attitude control device 4 can be provided.

The internal space 68 of the first rod member 68
c and communication holes 46 and 76 for communicating the piston lower chamber 21b.
a, the feed screw mechanism (the first rod member 68) is provided.
Female screw 68a and the male screw member 7 of the second rod member 70
The rotational friction 0a) can be reduced by the pressure of the hydraulic oil acting from the lower piston chamber 21b side.

Next, FIGS. 9 and 10 show other embodiments of the electric motor constituting the actuator 6 of each embodiment. The electric motor 80 according to the present embodiment includes:
It is mounted on the vehicle body side member 24 via the elastic member 82 with the output shaft 80a oriented in the horizontal direction. Output shaft 80
A worm gear 84 is coaxially fixed to a. A gear 86 is coaxially fixed to the upper end of the second rod member 34 of the piston rod 26 in the first and second embodiments, and to the upper end of the second rod member 70 of the piston rod 66 in the third embodiment. The gear 86 and the worm gear 84 mesh with each other.

Thus, the output shaft 80 of the electric motor 80
The forward rotation or the reverse rotation of “a” is transmitted to the second rod members 34 and 70 via the worm gear 84 and the gear 86. As described above, by using the electric motor 80 in which the output shaft 80a is oriented in the horizontal direction, a more compact device configuration is achieved, and the degree of freedom of the vehicle layout can be greatly improved.

FIG. 11 shows an output shaft 80.
14 shows a fourth embodiment of an actuator 6 using an electric motor 80 with a directed horizontally. The same components as those of the other embodiments are denoted by the same reference numerals, and description thereof is omitted. Actuator 6 of the present embodiment
The male screw member 88 coaxially fixed to the output shaft 80a of the electric motor 80, and the male screw member 88 is screwed to a female screw 90a formed on the inner periphery, so that the male screw member 88 can move horizontally on the vehicle body side member 24. The disposed cylindrical hydraulic control unit 90
A first rod member 92 having a hollow cylindrical shape inserted in the cylinder, and a first rod member 92 which is externally inserted while maintaining liquid tightness at a lower end of the first rod member 92 and a piston 22 is connected to the lower end. It is composed of a two-rod member 94 and a tube 96 communicating between the through-hole 92 a of the first rod member 92 and the internal space 90 b of the hydraulic control unit 90. Note that the first rod member 92 and the second rod member 94 constitute the piston rod 98 of the present embodiment.

The hydraulic oil is sealed from the internal space 90b of the hydraulic control unit 90 to the internal space 94a of the second rod member 94 via the tube 92 and the through hole 92a of the first rod member 92. When the male screw member 88 rotates in the normal rotation direction by the normal rotation drive of the electric motor 28, the actuator 6 having the above configuration moves the hydraulic control unit 90 connected to the male screw member 88 to the right in FIG. Space 90
The volume of b decreases. Due to the decrease in the volume of the internal space 90b, the hydraulic oil pushed out from the internal space 90b is supplied to the tube 92 and the second rod member 92 through the second through hole 92a.
The first rod member 92 flows into the internal space 94a of the rod member 94 and moves upward due to an increase in the volume of the internal space 94a. As described above, when the electric motor 80 is driven to rotate forward, the first rod member 92 moves upward and the rod length of the piston rod 98 tends to increase, and the active damping force is increased by the rod expansion and contraction speed generated at that time. Occurs to suppress changes in vehicle attitude.

When the male screw member 88 rotates in the reverse direction by the reverse rotation of the electric motor 28, the hydraulic control unit 90 connected to the male screw member 88 moves to the left in FIG. Increase. Interior space 9
When the volume of the first rod member 92 increases, the hydraulic oil in the internal space 94a of the second rod member 94
a, the internal space 9 of the hydraulic control unit 90 via the tube 92
Returning to 0b, the first rod member 92 moves downward. As described above, when the electric motor 80 is driven to rotate in the reverse direction, the first rod member 92 moves downward to shorten the rod length of the piston rod 98, and an active damping force is generated due to the rod expansion and contraction speed generated at that time. To suppress a change in the attitude of the vehicle.

As a special effect of the present embodiment, the electric motor 80 with the output shaft 80a directed in the horizontal direction and the hydraulic control unit 90 for expanding and contracting the piston rod 98 by hydraulic pressure are arranged on the vehicle body side member 24. Thus, the piston rod 98 having a short natural length can be provided, and as in the other embodiments, it is possible to provide a compact device in which the degree of freedom in vehicle layout is greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a vehicle equipped with a posture control device of the present invention.

FIG. 2 is a view showing an actuator according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating details of a rotation preventing mechanism according to the first embodiment.

FIG. 4 is a dynamic model diagram in which a damping element including a feed screw mechanism of the present invention is added in series with a normal damping element.

FIG. 5 is a model diagram illustrating an operation of reducing a rotational friction of the feed screw mechanism in the first embodiment.

FIG. 6 is a view showing an actuator according to a second embodiment of the present invention.

FIG. 7 is a model diagram illustrating an operation of reducing a rotational friction of a feed screw mechanism in a second embodiment.

FIG. 8 is a view showing an actuator according to a third embodiment of the present invention.

FIG. 9 is a plan view showing another embodiment of the electric motor constituting the actuator.

FIG. 10 is a side view showing the electric motor shown in FIG.

FIG. 11 is a view showing an actuator according to a fourth embodiment of the present invention.

[Explanation of symbols]

 2FL to 2RR Wheel 4 Attitude control device 6 Actuator 16 Controller 18 Drive circuit 20 Cylinder 21b Lower piston chamber (one fluid chamber) 21a Upper piston chamber (other fluid chamber) 22 Piston 24 Body side member (Spring member) 26, 66, 98 Piston rod 28, 80 Electric motor (piston rod control means) 28a, 80a Output shaft 32, 68, 92 First rod member 32a, 68a, 90a Female screw 32b, 68c Internal space of first rod member 34, 70, 94 Second rod member 34a, 70a, 88 Male screw member 46, 60, 76a Communication hole 68b Male screw 70b Shaft hole 72 Third rod member 72a Spline 74 Fourth rod member 74a Female screw 84 Worm gear 86 Gear 90 Hydraulic control unit (piston rod control Means) 90b hydraulic system The interior space 96 tubes of the interior space (oil chamber) 94b second rod member parts

Claims (7)

[Claims] 1. A vehicle attitude control device for controlling a vehicle attitude by operating an actuator disposed between a sprung member and a sprung member of each wheel based on sensor information for detecting a vehicle state. A cylinder enclosing hydraulic oil connected to one of the unsprung member and the sprung member, a piston sliding in the cylinder by partitioning one fluid chamber and the other fluid chamber in the cylinder, One end is connected to the piston, and the other end is connected to the other of the unsprung member and the sprung member. A piston rod having a variable rod length, and a rod length of the piston rod based on the sensor information. And a piston rod control means for changing the position of the vehicle. 2. The attitude control apparatus for a vehicle according to claim 1, wherein the piston rod has a structure in which a plurality of rod members are connected in series via a feed screw mechanism, and the feed is controlled by the piston rod control means. An attitude control device for a vehicle, wherein the rod length is changed by relatively displacing each rod member in an axial direction by operating a screw mechanism. 3. The attitude control device for a vehicle according to claim 2, wherein the piston rod has an internal thread formed on an inner peripheral surface thereof, and the piston is connected to one end of the piston rod so that rotation of the piston is restricted in the cylinder. A hollow cylindrical first rod member that slides in the axial direction; and a male screw member that is coaxially inserted from the other end of the first rod member and that is screwed to the female screw at one end. A solid cylindrical second rod member to which the other of the unsprung member and the sprung member is connected, and wherein the piston rod control means controls the second rod member to a predetermined position. When the forward and reverse rotational force is transmitted,
The rotational force is transmitted to the female screw via the male screw, and the rotation of the first rod member is restricted, so that the rotational force is converted as a linear motion of the second rod member in the cylinder axial direction. An attitude control device for a vehicle, comprising: 4. The attitude control device for a vehicle according to claim 2, wherein one end of the piston rod, which has a female screw formed on an inner peripheral surface and a male screw formed on an outer peripheral surface, is inserted into a cylinder to restrict rotation. A first rod member having a hollow cylindrical shape that slides in the cylinder axis direction in the cylinder while being inserted into the first rod member, and one end of the other of the unsprung member and the sprung member is connected to one end, A male screw member is fixed to the other end, and the male screw member is screwed to the female screw of the first rod member. A second rod member is formed on the other end side of the second rod member through the male screw member. A third rod member that is inserted into the shaft hole and is movable in the cylinder axis direction while rotation is restricted, and a hollow cylindrical member having a piston connected to an end thereof, wherein the end of the third rod member is an inner end. Coaxially fixed to the bottom And a fourth rod member having an internal thread formed on the inner periphery thereof and being screwed with a male screw of the first rod member, wherein the fourth rod member is controlled with respect to the second rod member by control of the piston rod control means. When the forward and reverse rotational force is transmitted,
The rotational force is transmitted to the female screw via the male screw, and the rotation of the first rod member is restrained, so that the rotational force moves in a direction in which the second rod member and the fourth rod member are separated from each other. Alternatively, the second rod member and the fourth rod member are converted into a linear motion in a cylinder axial direction in a direction approaching each other. 5. The attitude control device for a vehicle according to claim 3, wherein the threaded portion of the male thread member of the second rod member and the female thread of the first rod member are located. And a fluid chamber in the cylinder in which the first and second rod members do not extend through a communication hole. 6. The vehicle attitude control device according to claim 3, wherein the threaded portion of the male screw member of the second rod member and the female screw of the first rod member is located. And a fluid chamber in the cylinder, which is an outer peripheral space of the first rod member, is communicated through a communication hole. 7. The vehicle attitude control device according to claim 1, wherein the piston rod control means includes a hydraulic control unit capable of changing the volume of an oil chamber, and the piston rod penetrates through an axial center position. A first rod member having a hole and inserted into the cylinder, and one end of the first rod member slidably inserted outside while maintaining liquid tightness, and the piston is connected to the first rod member; A second rod member, a tube communicating between a through hole of the first rod member and an oil chamber of a hydraulic control unit, and the tube, the through hole, An attitude control device for a vehicle, wherein hydraulic oil is filled up to an internal space of a second rod member defined by the first rod member.