JPS63227474A - Rear suspension for automobile - Google Patents

Abstract

PURPOSE:To improve safety of a vehicle on a road surface on which a vehicle is easy to slip, by a method wherein, in a device which supports a rocking member, supporting rear wheels, to a member on the car body side through a resilient member, the spring constant of the resilient member is variable based on the result of decision on whether a road surface friction factor is high or low. CONSTITUTION:In a device which vertically rockably supports a support member for each of rear wheels 1 on a shaft 6 supported to a member 5 on the car body through front and rear links 2 and 3, a resilient member 7 formed such that spring constants in directions X and Y are differed from each other and the spring constant is differed with an angle by formation of gap parts 73a in a part of a resilient annular ring 73 is located to a coupling part between each of the links 2 and 3 and the shaft 6. The resilient member 7 is rotationally displaceable through a link mechanism 11 through the action of an electric motor 9. The electric motor 9 is run and controlled so that a toe angle is changed such that when it is decided that the friction factor of a road surface is low, the outer rear wheel 1 is brought into a toe-in state and the inner rear wheel 1 is forced into a toe-out state by dint of a lateral force generated during turning.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rear suspension for an automobile.

Conventional technology For example, in a car that uses a parallel link type rear suspension in which the rear wheels are vertically supported by front and rear links, a hollow rubber bushing is installed at the point where the front and rear links connect to the body member side. The hardness of the rubber bushing can be adjusted according to the vehicle speed or steering angle by forming a section and introducing hydraulic pressure into the hollow section, and by changing the hydraulic pressure introduced into the hollow section depending on the vehicle speed or steering angle. This controls the rear wheels to tend to toe-in in response to lateral forces when driving at high speed, and controls the rear wheels to weaken the tendency to toe-in in response to lateral forces during large steering turns. It has been developed in the past and disclosed in Japanese Patent Application Laid-open No. 146707/1982 and No. 146708/1982.

Problems to be Solved by the Invention According to the conventional device as described above, it is possible to improve stability in high-speed driving ranges without significantly impairing turning performance in medium and low-speed driving ranges. However, the maneuverability and stability of a car depend on the suspension support (
In addition to the rigidity of the rubber bushing (rubber bushing) and the running speed, the coefficient of friction between the road surface and the tire changes greatly.
The above-mentioned method has a problem in that it cannot accurately adapt to maneuverability and stability on relatively low road surfaces.

The main purpose of the present invention is to address such problems.

Means for Solving the Problems The present invention provides a structure in which a swinging member that supports a rear wheel is attached and supported to a vehicle body side member at a plurality of locations via elastic members, and the plurality of elastic members are able to withstand lateral forces generated during turning. In an automobile rear suspension, which is configured to control changes in the toe angle of the rear wheels when turning by variably controlling the spring constants of the spring constants using output signals from the controller, the friction coefficient of the road surface is high or low. A means is provided for inputting a signal to the controller, which is a factor for determining whether the friction coefficient of the road surface is high or low. The controller should control the spring constant of each of the plurality of elastic members described above so that the toe angle changes such that the outer rear wheel is toe-in and the inner rear wheel is toe-out due to the lateral force generated when turning in all vehicle speed ranges. The device is characterized in that it is configured to emit an output signal.

Function As mentioned above, the spring constant control of the elastic member by the controller is changed depending on whether the road surface friction coefficient is high or low, so that the rear wheels can be prevented from skidding when turning on a slippery road surface with a low road surface friction coefficient. It is possible to increase the vehicle's suspension and improve stability on slippery roads, which enables control that accurately responds to all driving conditions.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 4 show an embodiment of the present invention. In FIG. 1, l is a rear wheel, and the tips of the front and rear links 2 and 3 are pivoted to the rear wheel l. and the previous and next links 2
The base end portions 21 and 31 of 3 are attached to a shaft 6 supported by a vehicle body side member 5 such as a cross member so as to be swingable in the vertical direction via an elastic member 7 as shown in FIG. . 4 is the rotation axis of the rear wheel 1.1.

Further, the tip of a radius rod 8 is attached to the rear wheel 1, and the base end 81 is attached to a vehicle body side member forward (or rearward) of the rear wheel via an elastic member so as to function as a swinging portion. The radius rod 8 is configured to support the load acting in the longitudinal direction.

As shown in FIG. 2, the elastic member 7 includes an inner cylinder 71, an outer cylinder 72 concentric with the inner cylinder 71, and a rubber or the like interposed and fixed between the inner cylinder 71 and the outer cylinder 72. For example, as shown in FIG. 2(a), a gap 73a may be formed in a part of the elastic ring 73, or a second
By embedding an intermediate plate 73b such as a metal plate in a part of the elastic inner ring 73 as shown in FIG. The spring constant is configured to change depending on the angle, such as a high spring constant in the direction, and when the elastic member 7 is interposed between the shaft 6 and the link base end, By rotating the elastic member 7 with respect to the link, the spring constant of the elastic member 7 relative to the main load on the rear wheel input via the link can be variably controlled.

Although an electric motor or a hydraulic device may be used as the actuator for rotating the elastic member 7, the illustrated embodiment shows an example in which an electric motor 9 is used.

That is, the electric motor 9 is attached to the vehicle body side member 5, and rotationally displaces the elastic member 7 with respect to the link base end via the reducer 10, link mechanism 11, etc.

FIG. 3 shows a specific example of the attachment portion of the elastic member 7. As shown in FIG.

That is, as shown in FIG. 3, the shaft 6 is rotatably fitted into and supported by a cylindrical member 12 fixed to the vehicle body side member 5 by welding or the like via a bearing 13. The inner cylinder 71 of the member 7 is fitted by means such as serration fitting, and the base end of the driven arm llc of the link mechanism 11 is fitted to one end of the shaft 6 by means such as serration fitting. Then, the nuts 14 are screwed onto the threaded portions at both ends of the shaft 6 and tightened to fix the elastic member 7, the driven arm llc, etc.

Of the elastic members 7 assembled and fixed to both ends of the shaft 6 as described above, a spherical collar 15 is press-fitted into the outer cylinder of the front elastic member 7a, and a retainer 16 is placed on the outer peripheral surface of the spherical collar 15. The base end 21 of the front link 2 is fitted and assembled so as to be rotatable, and the spherical collar 15 is press-fitted into the outer cylinder of the rear elastic member 7b. The base end portion 31 of the rear link 3 is fitted and assembled so as to be rotatable.

In FIG. 3, reference numeral 17 indicates the driven arm llc of the link mechanism 11 and the connecting rod 1 (having a length adjustment mechanism).
The other end of the connecting rod llb is a joint that connects one end of the connecting rod llb to the tip of the driving arm lla fixed to the output shaft of the reducer 10, as shown in FIG. 1 (rl). are connected via. 18 is an oil seal.

The electric motor 9 is operated by a controller 20 based on a vehicle speed signal from a sensor that detects the driving state, such as a vehicle speed sensor 19 that detects the vehicle speed, and a signal from sensors 19' that are elements that determine whether the friction coefficient of the road surface is high or low. The rotation direction, rotation angle, etc. are controlled by the output signal.

In the above, the left front and rear elastic members 7 are each 7a.
, 7b, and the front and rear elastic members 7 on the right side are respectively 7a',
7b', and the left and right elastic members 7b and 7b' on the rear side are assembled with an angular displacement of 90'' relative to the left and right elastic members 7a and 7a' on the front side, for example, as shown in FIG. 4(A). The front left and right elastic members 7a, 7a'' have a high spring constant in the left-right direction (the axial direction of the link 2) and a low spring constant in the vertical direction, and the rear left and right elastic members 7b,
7b' is a state in which the spring constant is low in the left-right direction (the axial direction of the link 3) and high in the vertical direction. In this state, the elastic members 7a, 7a' and 7 are caused by cornering force as a lateral force acting on the rear wheel 1.1 when turning.
b, 7b' is the amount of deflection of the front elastic members 7a, 7
The rear elastic members 7b and 7b' are larger than the rear elastic members 7b and 7b', so when turning, the outer rear wheel (hereinafter referred to as the outer wheel) is toe-out, and the inner rear wheel (hereinafter referred to as the inner wheel) is in a toe-in condition.

When the electric motor 9 rotates from the state shown in FIG. 4 (a) above and rotates the shafts 6, 6 by 45 degrees to the right via the link mechanism 11, the shafts 6, 6 are integrated with the shafts 6, 6 to the front and rear sides. All the elastic members 7 are rotated 45° to the right with respect to the base ends 21, 31 of each link 2.3, and all the elastic members 7a, 7a', 7b , 7b' has an intermediate spring constant (a spring constant between a low spring constant and a high spring constant) with respect to the lateral force input from each link,
Front elastic member 7a due to cornering force when turning
, 7a' and the rear elastic members 7b, 7b' have the same amount of deflection, and the toe angles of both the outer ring and the inner ring do not change.

In the condition shown in Figure 4 (a) of the ball chart, the outer ring toes out when turning.
Since the inner ring has toe-in, turning performance is improved and the fourth
In the state shown in Fig. 4 (n), the toe angle of both the outer and inner wheels does not change when turning, so the maneuverability is good mainly at normal vehicle speeds such as when driving at medium speeds, and as shown in Fig. 4 (c). In this state, when turning, the outer wheel toe-in and the inner wheel toe-out, which increases the resistance against skidding of the rear wheels and improves stability. Therefore, for example, in a low vehicle speed range, priority is given to turning performance and the state shown in Fig. 4 (a) is achieved, in a medium vehicle speed range the state is shown in Fig. 4 (a), and in a high vehicle speed range, safety is given priority and the state shown in Fig. 4 (a) is achieved. Approximately appropriate cornering characteristics can be obtained by controlling the switching between the states (4), (o), and (c) in FIG. 4 according to the vehicle speed, such as state (c).

However, the control according to the vehicle speed as described above is almost effective when the vehicle is traveling on a road where the coefficient of friction between the road surface and the tires is higher than a predetermined value (hereinafter referred to as Takabachi Road). On wet, snowy, or icy roads (hereinafter referred to as low end roads) where the distance between the road surface and the tires is low, the rear wheels tend to skid even when cornering at low speeds. The outer ring is toe out.

If the inner wheels are left in a toe-in condition, the rear wheels will be more likely to skid, which is extremely dangerous.

Therefore, in the present invention, the controller 20 first determines whether the road surface on which the vehicle is traveling is Takahiroji or Hyobachiji based on signals from the sensors 19' which are elements for determining whether the road surface is high or low. However, if the road is high, for example, as described above, the controller 20 performs control to select one of the states shown in FIG. If it is determined that this is the case, control is performed to maintain the toe angle in the state shown in Figure 4 (c) in all vehicle speed ranges regardless of the vehicle speed, that is, the state in which the toe angle changes such that the outer wheel toe-in and the inner wheel toe-out due to cornering force. It is composed of

As shown in Figure 4 (
By performing control to maintain state C), even when cornering at low vehicle speeds, the toe angle of the rear wheels changes such that the outer wheel is toe-in and the inner wheel is toe-out, increasing the force to prevent sideslips. Stability during cornering on slippery roads such as snowy or frozen roads can be significantly improved.

Note that when the controller 20 determines that it is Takabachiji,
As mentioned above, the state shown in FIG. 4(a) is in the low vehicle speed range, and the state in FIG. 4(o) is in the middle vehicle speed range.

In the high vehicle speed range, switching control may be performed depending on the vehicle speed, as shown in Figure 4 (c), but in other cases, for example, in the low and medium speed range, cornering force is used as shown in Figure 4 (0). It is also possible to adopt a control mode in which no toe angle changes occur and the outer wheel is toe-in and the inner wheel is toe-out due to cornering force only in the high vehicle speed range as shown in Figure 4 (c). In the case of a corner road, control may be adopted to maintain a state in which no toe angle change occurs due to cornering force as shown in FIG. 4(0) in all vehicle speed ranges.

For example, a vehicle speed sensor that determines whether the end of the road surface is high or low is a ground vehicle speed sensor such as a Doppler sensor. A method in which the controller 20 determines whether it is a high route or a low route based on the difference between the vehicle speed signal in step 19, or a driven wheel rotation speed sensor that detects the rotation speed of the driven wheels and a drive wheel rotation speed that detects the rotation speed of the driving wheels. A method may be adopted in which the controller 20 determines the road surface level based on the difference between the respective signals emitted from the sensors. Part-time 4-wheel drive vehicles typically switch to 4-wheel drive on slippery roads, so the 4-wheel drive switching signal is used as a factor in determining the low route; It may be configured such that when the controller 20 determines that the vehicle is on a high p road and enters four-wheel drive, the controller 20 determines that the vehicle is on a low p road. Furthermore, a manual switch that is manually switched by the driver is used, and the controller 20 changes from high p road control to low μ road control by the driver's switching operation of the manual switch.
It is also possible to switch to road control.

It should be noted that the specific structure of the elastic member and the rotation control structure of the elastic member may have any structure other than that of the illustrated embodiment within the scope of the object of the present invention. Not limited to type suspensions, any type of suspension such as trailing arm type or semi-trailing arm type, in which a swinging member that supports the rear wheel so that it can swing up and down is attached to and supported by elastic members at multiple locations on the vehicle body side member. It goes without saying that this can be applied to Norya Suspension Iris.

Effects of the Invention As described above, according to the present invention, the swinging member that supports the rear wheel is attached and supported to the vehicle body side member at a plurality of locations via elastic members, and the plurality of elastic members act on the rear wheel. In an automobile rear suspension configured to control changes in the toe angle of the rear wheels during turning by variably controlling spring constants for lateral forces using output signals from the controller, the controller automatically or instructs the driver to The controller determines whether the coefficient of friction of the road surface is high or low by operating a switch, and when it determines that the coefficient of friction is low, the controller controls toe-in for the outer wheels and toe-out for the inner wheels based on the lateral force generated when turning in all vehicle speed ranges. By controlling the spring constants of the plurality of elastic members described above so that the toe angle of the rear wheel changes, the stability is significantly improved when driving on slippery roads such as wet, snowy, or icy roads. By combining the present invention with rear wheel toe angle change control during cornering according to the vehicle speed when the controller determines that the friction coefficient of the road surface is high, for example, the present invention can be used to improve safety under all driving conditions. , which enables more comfortable driving and can bring about great practical effects.

[Brief explanation of the drawing]

Figures 1 (4) and (El) are plan and front views showing embodiments of the present invention, and Figures 2 (a) and (α) are structural examples of elastic members used in the present invention, respectively. The front view shown in FIG. , (o) ,
(c) is a front view showing an example of a rotation control mode of four elastic members on the front left and right and the rear left and right which are interposed in the attachment support portion of the link to the vehicle body side member. l... Rear wheel, 2.3... Link, 5... Vehicle body side member, 6... Axis, 7... Elastic member, 9... Electric motor, 19... Vehicle speed sensor, 19”...sensors that are elements for determining the road surface friction coefficient, 20...controller.

Claims (4)

[Claims] (1) The swinging member that supports the rear wheels is attached and supported at multiple locations on the vehicle body side member via elastic members, and the spring constants of the plurality of elastic members against the lateral force generated during turning are output signals from the controller. In the rear suspension of an automobile configured to be able to control changes in the toe angle of the rear wheels during turning by variably controlling each of A means for inputting the signal to the controller is provided, and the controller determines whether the coefficient of friction of the road surface is high or low based on the signal, and when the controller determines that the coefficient of friction of the road surface is low, the controller determines whether the coefficient of friction of the road surface is low or not. The invention is characterized in that the output signal is configured to emit an output signal to control the spring constant of each of the plurality of elastic members in a state where the toe angle changes such that the outer rear wheel changes toe-in and the inner rear wheel changes toe-out due to a lateral force. Rear suspension for automobiles. (2) When the controller determines that the friction coefficient of the road surface is high, the lateral force generated during turning causes the outer wheels to toe out and the inner wheels toe in at low speeds, and both the outer and inner wheels toe at medium speeds. Claims characterized in that the spring constants of the plurality of elastic members are controlled according to the vehicle speed so that the outer ring is in a toe-in state and the inner ring is in a toe-out state in a high vehicle speed range with no angular change. The automobile rear suspension according to item 1. (3) When the controller determines that the friction coefficient of the road surface is high, due to the lateral force generated during turning, the toe angle of both the outer and inner wheels does not change in the low to medium speed range, and the outer wheel causes toe-in in the high speed range. Claim 1, characterized in that the spring constants of the plurality of elastic members are controlled according to the vehicle speed so that the inner ring is in a toe-out state.
The rear suspension for automobiles described in section. (4) When the controller determines that the coefficient of friction of the road surface is high, the controller uses springs made of multiple elastic members so that the toe angle of both the outer and inner wheels does not change due to the lateral force generated during turning in all vehicle speed ranges. 2. The rear suspension for an automobile according to claim 1, wherein the rear suspension maintains a constant.