JP6017813B2 - Rear suspension device - Google Patents

Description

  The present invention relates to a rear suspension device for a vehicle such as an automobile, and more particularly to an improved responsiveness at the beginning of turning.

2. Description of the Related Art A rear suspension device for an automobile or the like positions a hub bearing housing that rotatably supports a rear wheel with respect to a vehicle body via a spring system including a spring and a damper.
Such a rear suspension device is provided with an elastic body such as a rubber bush at one or both ends of a suspension arm (link) that is swingably connected to the housing and the vehicle body side for vibration isolation.
Further, the end of the suspension arm on the vehicle body side may be connected to the subframe, and an elastic body mount may be provided between the subframe and the vehicle body.

In recent years, it has been proposed that the rigidity of such an anti-vibration elastic body be variable, or that an actuator be incorporated in the anti-vibration elastic body.
For example, Patent Document 1 describes a technique in which an elastic body used as a suspension bush is a liquid seal bush and the rear wheel is made toe-in tendency by controlling the hydraulic pressure of hydraulic fluid during braking.
Japanese Patent Application Laid-Open No. 2004-228688 describes that an anti-vibration effect is enhanced by incorporating an actuator in an engine mount that supports the engine and controlling the actuator based on the vibration state of the engine.

JP 2008-126810 A JP 2005-3050 A

A load in the direction of pulling the vehicle toward the turning center is applied to the rear wheel suspension inside the turning of the vehicle at the time of steady turning, but the cornering force of the front wheel is applied at the beginning of turning immediately after the driver turns the vehicle. As a result, the vehicle body begins to change its direction, but the rear wheel tends to continue straight, and a lateral load in the compression direction temporarily acts on the suspension arm.
If the subframe mount, bushing, etc. of the rear suspension are elastically deformed due to such a load, the rear part of the vehicle body is relatively displaced inward of the turning with respect to the rear wheel, and the lateral force generation of the rear wheel tire is delayed, which causes The followability of the wheels deteriorates, and the response of the vehicle body behavior decreases.
In view of the above-described problems, an object of the present invention is to provide a rear suspension device that improves the response of the vehicle body behavior to a turning operation at the early stage of turning.

The present invention solves the above-described problems by the following means.
The invention according to claim 1, a rear subframe mounted through the front elastic mount and the rear elastic mount is disposed on the left and right sides of the Li Asabu frame to the vehicle body, the rear wheels of the vehicle A hub bearing housing that is rotatably supported, and a suspension arm that is swingably connected to the hub bearing housing and the rear subframe, and transmits a lateral load between the hub bearing housing and the rear subframe. A suspension start detecting means for detecting the start of turning of the vehicle, and a rigidity variable means for improving the rigidity of the front elastic body mount in response to the detection of the turning start, The stiffness varying means improves the stiffness of the front elastic body mount only on the turning inner ring side. A A suspension apparatus.
According to this, at the beginning of turning before centrifugal force is generated at the rear part of the vehicle body, the rear part of the vehicle body is restrained from moving relative to the rear wheel toward the inside of the turning, and the lateral force generation of the rear wheel tires is accelerated. Steering response delay around the wheel can be improved.

Furthermore, the above-described effects can be obtained more effectively by improving the rigidity of the front elastic body mount at the time when the lateral force is generated earlier than the rear side and easily obtaining the above-described effects.

The invention according to claim 2, wherein the rigidity changing means is a rear suspension apparatus according to claim 1, characterized in that to return the rigidity of the elastic body mount after a turning start after a preset time is there.
According to this, rigidity return control after improving the rigidity of the elastic body mount can be appropriately performed.

The invention according to claim 3 is provided with a steering angle increase detection means for detecting an increase in the steering angle by the driver, and the rigidity variable means has the predetermined time elapsed when the increase in the steering angle increase is detected. 3. The vehicle rear suspension apparatus according to claim 2 , wherein the elastic body mount is maintained in a state in which the rigidity of the elastic body mount is improved even in such a case.
According to this, when the driver performs an additional operation, the responsiveness to the additional operation can be improved by maintaining the rigidity of the elastic body mount in an improved state.

According to a fourth aspect of the present invention, there is provided a hub bearing housing that rotatably supports a rear wheel of a vehicle, and a hub bearing housing and a vehicle body side member provided on the vehicle body so as to be swingable. A rear arm having a plurality of suspension arms spaced apart in the front-rear direction and transmitting a lateral load to the vehicle body side member; and an elastic bush provided at at least one end of the suspension arm a suspension device, a turning start detecting means for detecting the turning start of the vehicle, variable stiffness to improve accordingly the rigidity of the elastic body bushing of the suspension arm of the swivel inner ring side and the front side only on the detection of the orbiting start a rear suspension apparatus according to claim Rukoto and means.

The invention according to claim 5 is the rear suspension device according to claim 4 , wherein the stiffness varying means restores the stiffness of the elastic bushing after a predetermined time has elapsed after the start of turning. is there.

The invention according to claim 6 is provided with a steering angle increase detection means for detecting an increase in the steering angle by the driver, and the rigidity varying means has the predetermined time elapsed when the increase in the steering angle increase is detected. 6. The rear suspension device according to claim 5 , wherein the rigidity of the elastic body bush is maintained in an improved state even when the elastic body bush is improved.
Also in the inventions according to claims 4 to 6 described above, substantially the same effects as those of the inventions according to claims 1 to 3 described above can be obtained.

  As described above, according to the present invention, it is possible to provide a rear suspension device that improves the responsiveness of the behavior of the vehicle body with respect to a steering operation at the beginning of turning.

1 is a schematic plan view of a vehicle equipped with a first embodiment of a rear suspension device of the present invention. It is a block diagram which shows the structure of the rigidity control system of the rear sub-frame mount in the rear suspension apparatus of Example 1. FIG. 4 is a flowchart illustrating rigidity control of a rear subframe mount in the rear suspension device of the first embodiment. 6 is a graph schematically showing an example of a transition of a vehicle body yaw rate and a rear suspension arm load at an initial turning time in a vehicle having a rear suspension of Example 1 and a comparative example.

  The present invention provides a problem of providing a rear suspension device that improves the response of a vehicle body behavior to a steering operation at an early stage of turning, and is provided between a rear subframe to which a vehicle body side end portion of a suspension arm is connected and a vehicle body. Among the elastic mounts, those on the turning inner ring side have been solved by improving the rigidity over a predetermined period from the start of turning.

Embodiment 1 of a rear suspension device to which the present invention is applied will be described below.
FIG. 1 is a schematic plan view of a vehicle including a rear suspension device according to a first embodiment.
The vehicle is, for example, an automobile such as a four-wheeled passenger car, and includes left and right front wheels W _FL and W _FR and left and right rear wheels W _RL and W _RR that are steering wheels.

The rear suspension device includes a rear subframe 10, a front mount 20, a rear mount 30, a housing 40, a suspension arm 50, and a spring, a damper, a stabilizer, and the like (not shown).
In the following description, members provided symmetrically are shown and described with reference numerals L and R on the left and right sides, respectively.

The rear subframe 10 is formed of a metal material such as steel or aluminum alloy, for example, in a frame shape having a substantially rectangular shape when viewed from above the vehicle.
The rear subframe 10 is attached to the vehicle body in a floating state via a front mount 20 that is an elastic body mount and a rear mount 30.

The front mount 20 (20L, 20R) supports the front end portion of the rear sub-frame 10, and is provided with a pair spaced apart in the vehicle width direction.
The front mount 20 is a cylindrical outer cylinder (not shown) fixed to the rear subframe 10 and a cylindrical outer cylinder (not shown) that is inserted substantially concentrically on the inner diameter side of the outer cylinder and fastened to the vehicle body side by a bolt or the like. And an inner cylinder. A rubber portion (not shown) is provided between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder. The rubber part is joined to the outer cylinder and the inner cylinder by vulcanization adhesion.
The front mount 20 is fixed to the rear subframe 10 with the central axis of the outer cylinder substantially aligned with the vertical direction.

The front mount 20 (20L, 20R) can independently change the compression stiffness along the load in the vehicle width direction at the outer half 21 (21L, 21R: the portion shown in black in FIG. 1) in the vehicle width direction. Variable rigidity mount.
Such a change in rigidity is achieved by, for example, using the front mounts 20L and 20R as liquid seal mounts, switching the hydraulic fluid pressure or hydraulic fluid flow path, or using the hydraulic fluid whose viscosity changes according to the strength of the magnetic field. This can be realized by a known technique.

The rear mount 30 (30L, 30R) supports the rear end portion of the rear subframe 10, and is provided with a pair spaced apart in the vehicle width direction.
The rear mount 30 is a cylindrical outer cylinder (not shown) fixed to the rear subframe 10, and a cylindrical outer cylinder (not shown) that is inserted substantially concentrically on the inner diameter side of the outer cylinder and fastened to the vehicle body side by a bolt or the like. And an inner cylinder. A rubber portion (not shown) is provided between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder. The rubber part is joined to the outer cylinder and the inner cylinder by vulcanization adhesion.
The rear mount 30 is fixed to the rear subframe 10 in a state where the central axis of the outer cylinder is substantially along the vertical direction.

The housing 40 is a member (hub bearing housing) that houses a hub bearing that rotatably supports a hub to which the rear wheels W _RL and W _RR are fixed.

The suspension arm 50 is a link group that supports the housing 40 so as to be swingable with respect to the vehicle body along a predetermined locus.
The suspension arm 50 includes a front lateral arm 51, a rear lateral arm 52, a trailing arm 53, and an upper arm (not shown).

The front lateral arm 51 and the rear lateral arm 52 extend substantially along the vehicle width direction and are spaced apart in the front-rear direction.
The outer lateral ends of the front lateral arm 51 and the rear lateral arm 52 are connected to the housing 40 so as to be swingable.
End portions on the inner side in the vehicle width direction of the front lateral arm 51 and the rear lateral arm 52 are disposed on the side portion of the rear subframe 10 so as to be swingable.

The trailing arm 53 is swingably connected to the front end portion of the rear subframe 10 and the front end portion of the housing 40.
The trailing arm 53 is for positioning the housing 40 mainly in the front-rear direction.
The upper arm is swingably connected to the housing 40 and the rear subframe 10 above the front lateral arm 51 and the rear lateral arm 52, respectively, and mainly positions the camber angle of the rear wheel.
Each of these arms has an elastic bush such as a rubber bush at both ends, and is connected to the rear subframe 10 and the housing 40 via the elastic bush.

FIG. 2 is a block diagram illustrating a configuration of a rigidity control system for the rear subframe mount according to the first embodiment.
The rear subframe mount stiffness control system 100 includes a rear subframe mount control unit 110, a steering angle sensor 120, and the like.
The rear subframe mount control unit 110 individually changes the rigidity (hardness) of the left and right front mounts 20L and 20R of the rear subframe 10 based on the output of the steering angle sensor 120 and the like.
The rear subframe mount control unit 110 includes an information processing device such as a CPU, a storage device such as a RAM and a ROM, an input / output device, a bus for connecting them, and the like.

  The steering rudder angle sensor 120 is provided on a steering shaft, which is a rotating shaft that transmits rotation to a steering gear box, from a steering wheel that is steered by a driver, and includes an encoder that sequentially detects the rudder angle of the steering system.

FIG. 3 is a flowchart showing the rigidity control of the rear subframe mount in the first embodiment.
Hereinafter, the steps will be described step by step.
<Step S01: Judgment of turning determination establishment>
The rear subframe mount control unit 110 determines whether or not the vehicle has transitioned from the straight traveling state to the turning state based on the output of the steering angle sensor 120.
For example, the rear subframe mount control unit 110 makes a turning determination when the steering angle detected by the steering angle sensor 120 is equal to or greater than a predetermined value and the angular velocity obtained by time-differentiating the steering angle is equal to or greater than a predetermined value. Can be established.
When the turning determination is established, the process proceeds to step S02.
On the other hand, when turning determination is not materialized, it returns, returns to step S01 again, and repeats the subsequent processes.

<Step S02: Steering direction determination>
The rear subframe mount control unit 110 determines the left and right of the steering direction (turning direction) based on the output of the steering angle sensor 120.
Thereafter, the process proceeds to step S03.

<Step S03: Curling inner mount curing>
The rear subframe mount control unit 110 outputs a control signal for improving the rigidity (hardness) of the front mount 20 on the inner side (right side if turning right, left side if turning left) with respect to the turning direction. To do.
The front mount 20 immediately improves the rigidity (hardness) according to the control signal.
For example, in the case of a left turn as shown in FIG. 1, the left front mount 20L is cured.
Thereafter, the process proceeds to step S04.

<Step S04: Judgment of elapsed time after steering detection>
The rear sub-frame mount control unit 100 detects a steering operation in step S01, and determines whether or not the elapsed time since the turning determination is established has passed a predetermined value (threshold value) t. To do.
If the elapsed time has passed t, the process proceeds to step S05, and if not, step S04 is repeated.

<Step S05: Determination of Steering Increase>
The rear subframe mount control unit 100 determines whether or not the driver has performed a steering turning increase operation based on the output of the steering angle sensor 120.
For example, when the steering angle is increased and the steering angular velocity is equal to or higher than a predetermined value with respect to the previous state, it is possible to establish the increase determination.
If the rounding determination is not established, the process proceeds to step S07, and if established, the process proceeds to step S06.

<Step S06: Judgment of Elapsed Time after Additional Check>
The rear sub-frame mount control unit 100 detects a round-up operation in step S05, and whether or not the elapsed time after establishing the round-up determination has passed a preset predetermined value (threshold value) t ′. Is determined.
If the elapsed time has passed t ′, the process proceeds to step S07, and if not, step S06 is repeated.

<Step S07: Turn Inside Mount Hardening Return (Softening)>
The rear sub-frame mount control unit 100 returns (softens) the rigidity (hardness) of the hardened front mount 20 in step S03 to the previous state and ends (returns) a series of processes.

Hereinafter, the effect of Example 1 mentioned above is demonstrated in contrast with the comparative example of this invention demonstrated below.
In addition, in the comparative example and Example 2 demonstrated below, the same code | symbol is attached | subjected about the location substantially the same as Example 1, and description is abbreviate | omitted and it mainly demonstrates a difference.
In the rear suspension device of Comparative Example 1, the front mount 20 is not provided with a variable stiffness mechanism.

FIG. 4 is a graph schematically showing an example of the transition of the vehicle body yaw rate and the rear suspension arm load at the beginning of turning in the vehicle having the rear suspension device of the first embodiment and the comparative example.
In FIG. 4, the steering angle (common to both the first and comparative examples), the vehicle body yaw rate (vehicle body behavior) of the first embodiment, the load of the front lateral arm 51, the vehicle body yaw rate of the comparative example, and the load of the front lateral arm 51, respectively. A solid line, a broken line, a one-dot chain line, a two-dot chain line, and a three-dot chain line are illustrated.
As for the load of the front lateral arm, the upper side in the figure is a tensile load and the lower side is a compressive load.

  In the comparative example, after the vehicle body started to change direction due to the cornering force of the front wheels at the beginning of turning, the rear part of the vehicle follows the front part of the vehicle and tries to displace inward in the turning direction. The load is applied, and then the lateral force of the rear wheel tire is generated, the load reverses and turns into a tensile load, and enters a steady turning state.

  On the other hand, according to the first embodiment, by improving the rigidity of the half portion 21 on the outer side in the vehicle width direction of the front mount 20 inside the turning at the beginning of turning, the support rigidity of the rear subframe 10 with respect to the vehicle body is strengthened. By suppressing the inward turning of the rear part of the vehicle body, the lateral force of the rear wheel tire is generated earlier than in the comparative example, and the timing at which the load reverses to the tension side is advanced so that the vehicle body behavior with respect to the steering operation Responsiveness can be improved.

Next, a second embodiment of the rear suspension device to which the present invention is applied will be described.
In the rear suspension device of the second embodiment, instead of the front mount 20 of the rear subframe 10, an elastic bush (not shown) provided at the connecting portion between the front lateral arm 51 and the rear subframe 10 is made variable in rigidity. The same variable stiffness control as that of the front mount 20 is performed.
In the second embodiment described above, it is possible to obtain substantially the same effect as that of the first embodiment described above.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) means for detecting the start swivel is not limited to using the steering angle and angular velocity, such as in each embodiment. For example, the angular acceleration of the steering angle may be used.
Further, the start of turning may be detected based on the yaw rate of the vehicle body or the lateral acceleration.
In addition, it is possible to improve the rigidity of the elastic body mount and the elastic body bush by predicting the transition from the straight traveling state to the turning state from the output of a positioning device such as a car navigation device or an external recognition device such as a stereo camera. Good.
( 2 ) The suspension arm of the rear suspension device according to the second embodiment is attached to a rear subframe whose end on the vehicle body side is mounted on the vehicle body via an elastic body mount. You may make it attach to the bracket directly attached to the sub-frame, cross member, or monocoque vehicle body attached without attaching. Also, the suspension type is not particularly limited.

W _FL , W _FR front wheels W _RL , W _RR rear wheels 10 Rear subframe 20 (20L, 20R) Front mount 30 (30L, 30R) Rear mount 40 (40L, 40R) Housing 50 Suspension arm 51 (51L, 51R) Front Lateral arm 52 (52L, 52R) Rear lateral arm 53 (53L, 53R) Trailing arm 100 Stiffness control system 110 Rear subframe mount control unit 120 Steering angle sensor

Claims (6)

A rear subframe mounted through the front elastic mount and the rear elastic mount is disposed on the left and right sides of the Li Asabu frame to the vehicle body,
A hub bearing housing that rotatably supports the rear wheel of the vehicle;
A suspension device that includes a suspension arm that is swingably connected to the hub bearing housing and the rear subframe, and that transmits a lateral load between the hub bearing housing and the rear subframe,
A turning start detecting means for detecting the turning start of the vehicle;
A rigidity varying means for improving the rigidity of the front elastic body mount in response to detection of the turning start,
The rear suspension apparatus, wherein the rigidity varying means improves the rigidity of the front elastic body mount only on the turning inner ring side. 2. The rear suspension device according to claim 1, wherein the stiffness varying unit returns the stiffness of the elastic body mount after a predetermined time has elapsed after the start of turning. A rudder angle increase detection means for detecting an increase in rudder angle increase by the driver is provided,
The rigidity varying means maintains a state where the rigidity of the elastic body mount is improved even when the predetermined time has elapsed when the steering angle increase is detected. Item 3. The vehicle rear suspension device according to Item 2. A hub bearing housing that rotatably supports the rear wheel of the vehicle;
The hub bearing housing and the vehicle body side member provided on the vehicle body are swingably connected, and a plurality of hub bearing housings and a vehicle body side member are arranged apart from each other in the front-rear direction. A suspension arm for transmission,
A rear suspension device having an elastic bush provided at at least one end of the suspension arm,
A turning start detecting means for detecting the turning start of the vehicle;
Rear suspension apparatus according to claim Rukoto a rigidity changing means for increasing in accordance with the rigidity of the elastic body bushing of the suspension arm of the swivel inner ring side and the front side only on the detection of the turning start. The rear suspension device according to claim 4, wherein the stiffness varying means restores the stiffness of the elastic body bush after a predetermined time has elapsed after the start of turning. A rudder angle increase detection means for detecting an increase in rudder angle increase by the driver is provided,
The rigidity variable means maintains the state where the rigidity of the elastic bush is improved even when the predetermined time has elapsed when the steering angle increase is detected. Item 6. The rear suspension device according to Item 5.

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