STABILIZER

Abstract: The central portion (1a) of a generally C-shaped bar (1) is formed as a torsionbar, and both end portions (1b) are formed as arms. The bar is mounted under a vehicle body (not shown) through mounting portions (2) such that the central portion is rotatable about its own axis. Each of the both arms (1b) support by a wheel through a vertical stabi-link (3), including a connecting means (A) inserted between the torsion bar and the wheel and adapted to be controllable in rotation and or pivoting angle and connecting force. Thus a control of the rolling stiffness of the vehicle in response to vehicle speed, steening angle and/or road surface condition is achieved.

Description: The present invention relates to a stabilizer for a vehicle. The stabilizer is combined in the suspension system of a vehicle to increase rolling stiffness of the vehicle, and to increase steering stability of the vehicle when cornering or high speed running. In a stabilizer shown in EP-A-0 463 033, a non-prepublished document belonging to the state of the art according to Article 54 (3) EPC, there is a central portion which acts as a torsion bar and is mounted under a vehicle body and two arms connected to a wheel suspension member through a vertical stabi-link. A rotary actuator is inserted between the torsion bar and the wheel and is adapted to be controllable in rotation and/or pivoting angle and connecting force. Another known stabilizer is shown Fig. 7. The central portion 1a of a generally C-shaped bar 1 is formed as a torsion bar, and both end portions 1b are formed as arms. The bar 1 is mounted under a vehicle body (not shown) through mounting portion 2 such that the central portion 1a is rotatable about its own axis. Each of the arms 1b is attached through a stabi-link 3 and a lower arm 4 to wheel (not shown). Rolling stiffness of the vehicle is improved by connecting the left and right wheels through the torsion bar 1a. When a vehicle having such a stabilizer runs on a rough road and when one of the wheels heavily bounds from the road surface, or one wheel rides over a projected portion of the road, the other wheel follows the upward motion by the stabilizer thereby impairing, comfort of the vehicle passengers. Especially, with four wheel drive vehicles designed to run on rough roads, such as mountain tracks, this upward stabilizer motion can cause insufficient traction of the wheel. Accordingly, the object of the present invention is to provide an improved stabilizer for a vehicle in which the comfort of vehicle passengers is not impaired by decreasing follow-up of the other wheel even when one wheel bounds largely when the vehicle is running on rough roads at relatively low speed, and when one wheel rides on a mound when the vehicle is running straight at high speed. To achieve the above-mentioned object, the stabilizer, according to the present invention, includes a central portion which acts as a torsion bar and is mounted under a vehicle body, and two arms connected to a wheel suspension member through a vertical stabi-link each of said arms being connected to a respective stabi-link by connecting means which includes a casing connected with the stabi-link, a ring secured with the arm of the stabilizer and rotatably supported in the casing, a recess formed on the ring, a rod engaged in the recess, and an actuator acting on the rod, said actuator providing a controllable force and the angle of rotation between said arm and said stabi-link being controllable by controlling the force developed by said actuator. By controlling dependency between left and right wheels in response to vehicle function, according to the present invention, one wheel follows motion of the other wheel when the vehicle steers on flat road. However, upon straight high speed running on a high-way and at relatively slow speed running on a rough road, at least a portion of the follow-up function of the other wheel is eliminated or delayed so that large motion of one wheel is not directly transmitted to the other wheel ensuring improved smoothness and comfort. For a fuller understanding of the nature and objects of the present invention, reference should be made to the detailed description taken in conjunction with the accompanying drawings. Fig. 1 is a perspective view of a stabilizer, according to one embodiment of the present invention; Figs. 2 and 3 are perspective views of stabilizers, according to other embodiments of the present invention; Figs. 4 and 5 are link mechanisms of the stabilizer shown in Fig. 1; Fig. 6 is an enlarged sectional view of the link of the stabilizer shown in Fig. 1; and Fig. 7 is a perspective view of a conventional stabilizer. As shown in the drawings, according to the present invention, the connecting means which is controllable in rotation and/or pivoting angle and connecting force is inserted in the known stabilizer shown in Fig. 7 to change dependency between left and right wheels. Such inserted elements shown in Figs. 1 to 5 are as follows: A: a connecting means which is changeable in rotation angle, B and C: pivotable rotation joint, D: a rotation connecting means, and E: a connecting means which is changeable inpivoting angle. In all the drawings, the same reference numeral shows the same or similar part or portion for the sake of clarity. Referring to Fig. 1 which shows one embodiment of a stabilizer, according to the present invention, the connecting means A, B and C are used. A link 10 having the connecting means A is inserted between the arm 1b and the stabi-link 3, and the pivotable rotation joint B and C are inserted in upper and lower portions of the stabi-link 1b. The motion of the links 10 and 3 in the direction of arrow 5 in Fig. 1 is shown in Figs. 4 and 5, in which Fig. 4 shows the arm 1b inoperative and Fig. 5 shows the arm 1b operative to perform normal stabilizer function. The solid lines in Figs. 4 and 5 show that both lower suspension members 4 perform the same motion. When one lower member 4 moves vertically, the joint C moves vertically in the drawings. As shown in Fig. 5, when the connecting means A of the link 10 is secured, the motion of the joint C is transmitted through the links 10 and 3 to the arm 1b to perform pivoting of the arm 1b as a usual stabilizer. To impair all or a portion of the function of the stabilizer, the connecting means A of the link 10 is adapted that rotatable angle α is freely rotatable so that as shown in Fig. 4, within a range of the vertical motion of the joint C, angle β between the arm 1b of the stabilizer and the link 10 changes. Thus, the arm 1b does not swing about axis 6 and a portion of the function of the stabilizer is impaired. Consequently, when the connecting force of rotation or pivoting of the link 10 is changeable, the degree of impairment of the function of the stabilizer can be controlled. In Fig. 4, the range over the angle α and when angle α = 0, the connection between the link 10 and the arm 1b is rigid as shown in Fig. 5 so that function of the stabilizer is not impaired. Consequently, by inserting the link 10 permitting the rotation angle α of the connecting means A to be controlled, the rolling stiffness of the vehicle is changeable. The embodiment shown in Fig. 2 shows that the link 10 is connected perpendicular to the arm 1b of the stabilizer 1. As before, by controlling the free rotation angle and connecting force of rotation or pivoting, rolling stiffness of the vehicle can be controlled. The embodiment shown in Fig. 3 shows that a link 12 having a connecting means E which has a changeable pivoting angle. Fig. 6 shows one practical embodiment of the link 10 shown in Figs. 1 and 2, in which the arm 1b is shown as a phantom line in Fig. 1 and as a dotted circle line in Fig. 2 A ring 14 secured with the arm 1b is rotatably supported through a bearing 16 in a casing 18 which is formed in the link 10. The ring 14 forms a recess 20. In the link 10, a slider 22 is slidably engaged, and an end 24 of the slider 22 contacts with the recess 20. The rear end of the slider 22 engages with a spring 28 to maintain the coupling rigid. An actuator 26 such as a hydraulic device or solenoid applies force to the left shown in Fig. 6 to compensate for the spring force to float the connection between the slider 22 and the ring 14 at an angle. The rear end of the link 10 is connected through the connecting means B with the link 3. Dimension of the recess 20, strength of the spring 28 and actuating force of the actuator 26 are suitably selected. In the embodiment shown, when the actuator 26 is not applied, rigid connection between the arm 1b and the link 3 can be performed, and when the actuator is applied, free rotation of angle α can be realized. When the applied force of the actuator 26 is variably controlled, more precise control can be performed. As another embodiment, the spring 26 is applied in reverse direction shown in Fig. 6. Or, the spring 26 may be eliminated as desired. In this embodiment, the actuator 26 urges the slider 22 to the recess 20 in operation. Thus, in inoperative condition of the actuator 26, the connection floats at an angle. The control behavior may be changed as desired. The embodiments shown in the drawing aim to be easily attached to the already present stabilizer. The connecting means to allow a portion of the link mechanism control to be rigid or rotatable, according to the present invention, may be inserted in any portion between the torsion bar arm 1b and the respective stabi-link (3). According to the present invention, a portion or all the function of the stabilizer is controllably impaired when the vehicle is running straight at relatively high speed, and when the vehicle is running on rough roads at relatively low speed so that rolling stiffness of the vehicle and comfort of vehicle passengers are greatly improved.

Claims: A stabilizer including a central portion (1a) which acts as a torsion bar and is mounted under a vehicle body, and two arms (1b) connected to a wheel suspension member (4) through a vertical stabi-link (3) each of said arms (1b) being connected to a respective stabi-link (3) by connecting means which includes a casing (18) connected with the stabi-link (3), a ring (14) secured with the arm (1b) of the stabilizer and rotatably supported in the casing (18), a recess (20) formed on the ring (14), a rod (24) engaged in the recess (20), and an actuator (26) acting on the rod (24), said actuator (26) providing a controllable force and the angle of rotation between said arm (1b) and said stabi-link (3) being controllable by controlling the force developed by said actuator (26).

Inventors: UMEDA, HIROTAKA
Applicants: TRW STEERING & INDUSTRIAL PRODUCTS (JAPAN) CO., LTD.
Application year: 1990
Main classification: B60G21
IPC codes: B60G21, B60G17