JP2006182287A - Front suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front suspension device, capable of achieving both steering stability and ride comfort by solving problems specific to the front suspension device of a double wishbone type in which a lower end of a damper is installed on a lower arm for restricting vertical movement of a car body side end part of the lower arm. <P>SOLUTION: In this front suspension device 1, at a shaft support part 28 at a rear part of a type A lower arm 6, the lower arm 6 is shaft-supported through a bush 244 of which axis is set in the vertical direction of a car body. The bush 244 has a stopper part 2442b, and it abuts on the shaft support part 28, so that vertical movement of the lower arm 6 at the end part 6d is restricted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a front suspension device of an automobile, and more particularly, to a bush structure in a double wishbone type front suspension device.

  2. Description of the Related Art A front suspension device for an automobile is known in which a bush is interposed in a vehicle body side attachment portion of a suspension arm in order to achieve both handling stability and riding comfort. By interposing the bush, it is effective for buffering a light input where the damper does not respond, and is mainly effective for improving the ride comfort. Moreover, what provided what is called a currant part to the elastic body of a bush is also known (for example, patent document 1). Depending on the position of the currant portion, the spring characteristics can be different with respect to the input direction with respect to the elastic body, and delicate tuning of steering stability and riding comfort can be achieved. Furthermore, as a method of setting the axial direction of the bush, as in Patent Document 1, among the two attachment parts of the suspension arm and the vehicle body, the bush axis at one of the attachment parts is set in the vertical direction of the vehicle body. It is becoming popular. With such a configuration, the combination with the currant portion responds more softly to the input in the longitudinal direction of the vehicle body than in the case where the shaft center of the bush is set in the longitudinal direction of the vehicle body in both attachment parts. The suspension responds harder to the vehicle width direction input. The responsiveness in the longitudinal direction of the vehicle body affects the ride comfort, and the responsiveness in the vehicle width direction affects the steering stability. Therefore, by setting the axial center of the bush at one attachment site in the vertical direction of the vehicle body, it is possible to effectively achieve both steering stability and ride comfort.

JP 2000-71733 A

  Here, even when such a bush is provided, there is a difference in the degree of improvement in riding comfort depending on the type of suspension. In particular, the axis of the bush at one attachment site is in the vertical direction of the vehicle body. In the double wishbone type front suspension device in which the lower end of the damper is attached to the lower arm when set, the lower end of the damper is attached to the wheel support member as in Patent Document 1 at the initial stage of input from the road surface or braking. There was a phenomenon that the ride comfort was inferior to the type of front suspension device.

  As a result of investigating the cause, in the double wishbone type front suspension device in which the lower end of the damper is attached to the lower arm, it is considered that the cause is that the lower end of the damper is supported by a part of the lower arm. That is, when input from the road surface acts on the wheel side end of the lower arm, the support position of the lower end of the damper that does not follow the input serves as a fulcrum, and the vehicle side end of the lower arm moves upward or downward according to the lever principle. It was considered that this would make the ride uncomfortable at the initial stage of input from the road surface. In this regard, in the type in which the lower end of the damper is attached to the wheel support member as in Patent Document 1, the lower end portion of the damper is connected to the wheel support member, so that the lever principle as described above is applied to the lower arm. Does not work.

  To solve the problems unique to the double wishbone type in which the lower end of the damper is attached to the lower arm, for example, the hardness of the elastic body of the bush is increased to suppress the vertical movement of the end of the lower arm on the vehicle body side. A way to do this is conceivable. However, this solution inevitably deteriorates the ride comfort.

  Accordingly, the object of the present invention is to solve the problems specific to the double wishbone type front suspension device in which the lower end of the damper is attached to the lower arm, and to suppress the vertical movement of the vehicle body side end portion of the lower arm, thereby improving the steering stability. It is to provide a front suspension device that can achieve both a comfortable ride and a comfortable ride.

  According to the present invention, the double arm includes an upper arm and an A-type lower arm that are installed between the vehicle body and the wheel support member, and a damper that has an upper end attached to the vehicle body and a lower end attached to the A-type lower arm. In the wishbone type front suspension device, the vehicle body is provided to be separated in the front-rear direction of the vehicle body, and includes a front shaft support portion and a rear shaft support portion that respectively support two vehicle body side end portions of the A-type lower arm. The front shaft support portion pivotally supports the A-type lower arm on the vehicle body via a first bush having an axial center set in the front-rear direction of the vehicle body, and the rear shaft support portion is a vertical direction of the vehicle body. The A-type lower arm is pivotally supported on the vehicle body through a second bushing having a shaft center set at the shaft, and the second bush has a shaft center set in the vertical direction of the vehicle body. And an elastic body provided around the inner cylinder, wherein the elastic body is interposed between the inner cylinder and an end of the A-type lower arm, The curly part drilled in the main body part in a direction parallel to the axis of the second bush, and the upper and lower end parts of the main body part respectively protrude and come into contact with the rear shaft support part so as to contact the rear shaft support part. There is provided a front suspension device having a stopper portion that suppresses vertical movement of an end portion of the A-type lower arm.

  In the present invention, the first bush having an axial center set in the longitudinal direction of the vehicle body is used in the front shaft support portion, and the second bush having an axial center set in the vertical direction of the vehicle body is used in the rear shaft support portion. It is done. By setting the axis of the bush of one of the shaft support portions in the vertical direction of the vehicle body, both steering stability and ride comfort can be achieved. Here, the second bush of the rear shaft support portion includes the stopper portion. For this reason, when the end portion of the A-type lower arm moves up and down in the rear shaft support portion, the stopper portion of the second bush comes into contact with the rear shaft support portion and the vertical movement is suppressed. By providing the stopper portion at the upper and lower end portions of the main body portion, it is not necessary to increase the hardness of the elastic body. Therefore, in the present invention, by setting the axial center of the bush of one shaft support portion in the vertical direction of the vehicle body, in addition to being able to achieve both steering stability and ride comfort, a double wish in which the lower end of the damper is attached to the lower arm It solves the problems specific to the bone-type front suspension device, suppresses the vertical movement of the lower arm side of the vehicle body, and more effectively balances steering stability and ride comfort.

  In the present invention, it is desirable that the stopper portion extends on the axial center line of the first bush in the front shaft support portion in plan view.

  According to this configuration, it is possible to prevent the stopper portion from resisting the swinging of the A-type lower arm in the vertical direction of the vehicle body, and even if the stopper portion is provided, the characteristics of the front suspension device are hardly affected. Does not affect.

  In the present invention, the front suspension device includes a front-mounted steering gear unit, and a pair of tie rods that extend outward in the vehicle width direction and obliquely forward, and connect the steering gear unit and the wheel support member. A front suspension device for an automobile provided with the stopper portion extending in the front-rear direction of the vehicle body, two curling portions provided on both sides of the stopper portion, and the curling portion outward in the vehicle width direction. It is desirable that the portion is provided behind the curly portion inward in the vehicle width direction, and that the two currant portions are provided on a line that forms a predetermined angle with the front-rear direction of the vehicle body in plan view.

  According to this configuration, in the front midship type vehicle in which the engine mounting position is close to the passenger compartment side by adopting the steering gear unit as a front-end type, wheel toe-out during braking can be suppressed and the Ackermann geometry can be maintained. it can. In particular, the stopper portion extends in the front-rear direction of the vehicle body, and due to the arrangement of the curly portion, linear movement of the A-type lower arm to the rear of the vehicle body during braking is suppressed and moved outwardly of the vehicle body. . For this reason, the toe-out of the wheel at the time of braking can be suppressed effectively, and the Ackermann geometry can be maintained.

  In this case, it is desirable that the predetermined angle substantially coincides with an angle formed by the tie rod and the vehicle width direction when neutral in a plan view.

  According to this configuration, wheel toe-out during braking can be more effectively suppressed.

  In the present invention, it is preferable that the stopper portion has a contact surface that contacts the rear shaft support portion, and the contact surface is subjected to a process for reducing friction.

  According to this configuration, it is possible to reduce the friction between the stopper portion and the rear shaft support portion so that the elastic body can be smoothly deformed in the front-rear direction.

  In the present invention, it is desirable that the end surface of the stopper portion is set substantially flush with the end surface of the inner cylinder.

  According to this structure, the assembly | attachment of the edge part of the said 2nd bush and the said A type lower arm in the said back axis | shaft support part can be facilitated.

  In the present invention, the stopper portion may be a separate member from the main body portion.

  According to this configuration, it is possible to employ elastic materials having different characteristics between the main body portion and the stopper portion.

  In the present invention, the stopper portion and the main body portion may have different hardnesses.

  According to this configuration, the hardness of the stopper portion and the main body portion can be set, respectively, while suppressing vertical movement of the vehicle body side end portion of the A-type lower arm, more effective in both steering stability and riding comfort. Can be realized.

  As described above, according to the present invention, the problem specific to the double wishbone type front suspension device in which the lower end of the damper is attached to the lower arm is solved, and the vertical movement of the vehicle body side end portion of the lower arm is suppressed, Both handling stability and ride comfort can be achieved.

  FIG. 1 is a perspective view showing a front suspension apparatus 1 for an automobile according to an embodiment of the present invention. The front suspension device 1 is attached to a suspension cross member 2 which is a configuration on the vehicle body side. The suspension cross member 2 extends in the vehicle width direction and extends from both sides of the suspension cross member 2 toward the rear of the vehicle body. The U-shaped front member 2a is provided at both ends of the front member 2a in the vehicle width direction and extends upward. 2b and a rear member 2c extending in the vehicle width direction behind the front member 2a and having both ends fixed to the front member 2a.

  The front suspension apparatus 1 is a double wishbone type suspension apparatus, and includes two sets of an upper arm 4 and a lower arm 6 that are installed between a suspension cross member 2 and a left and right wheel support member 8 that are configured on the vehicle body side. . The wheel support member 8 is a member that rotatably supports the wheel 17 (see FIG. 3), the brake disc 19 and the like.

  The front suspension apparatus 1 also includes two sets of struts 10 each having an upper end attached to a not-illustrated portion of the vehicle body and a lower end attached to the lower arm 6. The strut 10 is configured by arranging a damper 12 and a coil spring 14 on the same axis. The lower end of the strut 10, that is, the lower end of the damper 12 is attached so that the strut 10 can swing around the vehicle front-rear direction in the middle part between both ends of the lower arm 6.

  In the case of this embodiment, it is assumed that the front suspension device 1 is mounted on an automobile equipped with a front-mounted steering gear unit 16. When the steering gear unit is a front-end type, a front midship layout in which the engine mounting position is close to the passenger compartment can be adopted, and the motor performance, particularly steering stability, can be improved. The front suspension device 1 of the present embodiment is particularly suitable for an automobile that requires such exercise performance.

  The steering gear unit 16 is fixed to the front member 2a so as to extend in the vehicle width direction on the front side of the suspension cross member 2. As the steering gear unit 16, either a rack and pinion type or a ball screw type steering device can be adopted. A pair of tie rods 18 are provided between the steering gear unit 16 and each wheel support member 8 so as to extend outward in the vehicle width direction and obliquely forward and connect them. The wheel is steered through.

  2 is a plan view of the front suspension device 1 as viewed from the front right side of the vehicle body, and FIG. 3 is a front view of the front suspension device 1 as viewed from the front side of the vehicle body. In FIG. 2, the strut 10 is omitted. 2 and 3 show the right front wheel side. Hereinafter, the right front wheel side will be described, but the left front wheel side has the same configuration.

As shown in FIG. 2, the upper arm 4 is an A-type arm having a front arm portion 4 a and a rear arm portion 4 b, and two end portions 4 c and 4 d on the vehicle body side are suspension cross members via bushes 241 and 242. 2 are supported by shaft support portions 20 and 22 provided on the upper member 2b. The shaft support portions 20 and 22 are spaced apart in the longitudinal direction of the vehicle body, and the shaft centers of the bushes 241 and 242 are set in the longitudinal direction of the vehicle body. Therefore, the shaft support portions 20 and 22 substantially support the upper arm 4 so as to be swingable in the vertical direction of the vehicle body. Each bush 241 and 242 can employ a general bush used in a suspension device. A wheel side end 4 e of the upper arm 4 is attached to a wheel support member 8. In the present embodiment, as shown in FIG. 3, the wheel support member 8 includes an upper arm connecting extension 8a extending upward and a lower arm connecting extension 8b extending downward. The end 4e of the upper arm 4 is attached to the upper end of the extension 8a via a ball joint 30 (see FIG. 2).

  The lower arm 6 is an A-type arm having a front arm portion 6a extending substantially in the vehicle width direction and a rear arm portion 6b extending obliquely forward in the vehicle width direction outward. The two end portions 6c and 6d on the vehicle body side are bushes. The shafts are pivotally supported by shaft support portions 26 and 28 provided on the front member 2a of the suspension cross member 2 via 243 and 244, respectively. The shaft support portions 26 and 28 are spaced apart from each other in the longitudinal direction of the vehicle body. The axial center of the bush 243 is set in the longitudinal direction of the vehicle body, and the axial center of the bush 244 is set in the vertical direction of the vehicle body. For this reason, the shaft support portion 26 substantially supports the upper arm 4 so that it can swing in the vertical direction of the vehicle body, and the shaft support portion 28 supports the upper arm 4 so that it can swing in the longitudinal direction of the vehicle body. . By setting the axial center of the bush 244 of one of the two shaft support portions 26 and 28 in the vertical direction of the vehicle body, both steering stability and ride comfort can be achieved.

  A wheel side end 6 e of the lower arm 6 is attached to the wheel support member 8. The end 6e of the lower arm 6 is attached to the lower end of the extension 8b via a ball joint 30 (see FIG. 2). In addition, illustration of the front arm part 6a is abbreviate | omitted in FIG.

  The bush 243 may be a general bush used in a suspension device. As for the bush 244, a bush having the following configuration is adopted in this embodiment. 4A is an external perspective view of the bush 244, FIG. 4B is a sectional view taken along line YY in FIG. 4A, and FIG. 4C is a sectional view taken along line ZZ in FIG. 4A. It is.

  The bush 244 has a substantially cylindrical shape as a whole, and an inner cylinder 2441 whose axis is set in the vertical direction of the vehicle body when mounted, an elastic body 2442 provided around the inner cylinder 2441, and a periphery of the elastic body 2442 And an outer cylinder 2443 provided on the outside. In this embodiment, the inner cylinder 2441 and the outer cylinder 2443 are made of a metal cylinder, and the inner cylinder 2441 has a smaller diameter and a longer overall length than the outer cylinder 2443. The elastic body 2442 is made of rubber or the like, and is fixed to the inner cylinder 2442 and the outer cylinder 2443 so as to fill a gap between them.

  The elastic body 2442 is interposed between the inner cylinder 2441 and the end of the lower arm 6 via the outer cylinder 2443, and the stopper part 2442b projecting vertically in the upper and lower ends of the main body 2442a. And are integrally provided. The main body portion 2442a is provided with a currant portion 2442c which is a through hole formed in a direction parallel to the axis of the inner cylinder 2441 (line A in FIG. 3). In the case of the present embodiment, two of the currant portions 2442c are provided.

  FIG. 5 is a cross-sectional view taken along line XX in FIG. 2 and shows a structure of a mounting portion of the bush 244 in the present embodiment. The vehicle body side end portion 6d of the rear arm portion 6b of the lower arm 6 is formed in a cylindrical shape in which a through hole in the vertical direction of the vehicle body is formed, and a bush 244 is press-fitted therein. The shaft support portion 28 is spaced apart in the vertical direction to form a gap, and a through hole is formed in the vertical direction of the vehicle body. Then, the end portion 6d into which the bush 244 is press-fitted is inserted into the gap, and the bolt 28a is inserted from the lower side of the vehicle body so as to penetrate the through hole of the shaft support portion 28 and the inner cylinder 2441 of the bush 244. On the upper side of the vehicle body 28, the nut 28b is screwed and fastened.

  With this configuration, the lower arm 6 is pivotally supported so as to be swingable in the front-rear direction of the vehicle body with the shaft portion of the bolt 28a as the swing center axis. Needless to say, the axial center of the inner tube 2441 of the bush 244 is disposed concentrically with the swing center line. In addition, a vertical gap is formed between the shaft support portion 28 and the end portion 6 d of the lower arm 6, and the end portion 6 d of the lower arm 6 is deformed with respect to the shaft support portion 28 by elastic deformation of the elastic body 2442 of the bush 244. It is allowed to move within a certain range relatively up and down. Further, due to the elastic deformation of the elastic body 2442, the end portion 6 d of the lower arm 6 is allowed to move within a certain range in the left and right front-rear direction relative to the shaft support portion 28. In this embodiment, since the curly portion 2442c is provided, when the end portion 6d of the lower arm 6 moves in the left-right and front-rear directions relative to the shaft support portion 28, the amount of elastic deformation of the elastic body 2442 varies depending on the moving direction. It will be a thing.

  Here, in the present embodiment, a stopper portion 2442b in which the bush 244 protrudes at the upper and lower end portions of the main body portion 2442a of the elastic body 2442 is provided. Therefore, when the end portion 6d of the lower arm 6 tries to move up and down relatively with respect to the shaft support portion 28, the stopper portion 2442b contacts the shaft support portion 28, and the elastic deformation of the elastic body 2442 is suppressed. As a result, the lower arm The vertical movement of the end portion 6d of 6 is suppressed.

  Next, the layout of the stopper portion 2442b and the currant portion 2442c in the present embodiment will be described with reference to FIG. FIG. 6 is a plan view of the peripheral structure of the lower arm 6 of the front suspension device 1. First, the layout of the stopper portion 2442b will be described. Various shapes can be adopted as the shape of the stopper portion 2442b. In this embodiment, the stopper portion 2442b is formed in a straight strip shape across the inner tube 2441 in plan view, and on the axis of the bush 243 of the shaft support portion 26 in plan view. (On line B).

  With this configuration, it is possible to prevent the stopper portion 2442b from resisting the swinging of the lower arm 6 in the vertical direction of the vehicle body. Even if the stopper portion 2442b is provided, the characteristics of the front suspension device 1 are improved. Has little effect. That is, when the stopper portion 2442b extends in a direction perpendicular to the swing center line B, the stopper portion 2442b bends with respect to the swing of the lower arm 6 in the vertical direction of the vehicle body. As in the present embodiment, the bending resistance of the stopper portion 2442b can be minimized by extending on the axis of the bush 243. On the other hand, since the stopper portion 2442b extends on the axis of the bush 243, the movement of the lower arm 6 in the longitudinal direction of the vehicle body is suppressed. As described later, this effectively suppresses wheel toe-out during braking and contributes to maintaining the Ackermann geometry.

  Next, the layout of the currant portion 2442c will be described. As shown in FIG. 6, in this embodiment, two currant portions 2442c are provided on both sides of the stopper portion 2442b, and the curly portion 2442c on the outer side in the vehicle width direction is behind the curly portion 2442c on the inner side in the vehicle width direction. Is provided. Further, the two curly portions 2442c are provided on a line that forms a predetermined angle with the front-rear direction of the vehicle body in plan view. Specifically, as shown in FIG. 6, the centers of the two currant portions 2442 c form an angle γ with the longitudinal direction (line B) of the vehicle body, and are set on a line C that passes through the axis of the inner cylinder 2441. The portions provided with the curly portions 2442c are more easily bent than the other portions. In the present embodiment, the curly portion 2442c on the outer side in the vehicle width direction is provided behind the curly portion 2442c on the inner side in the vehicle width direction, so that the bush 244 is easily deformed outward and rearward of the vehicle body. Further, in the present embodiment, since the two curly portions 2442c are set on the line C, when the bush 244 receives a force from the end 6d of the lower arm 6, it becomes easy to deform in the direction of the line C. As described later, this contributes to effectively suppressing toe-out of the wheel during braking and maintaining the Ackermann geometry.

  Next, the layout and the like of the tie rod 18 will be described with reference to FIG. The wheel support member 8 includes a knuckle arm 8c for connecting a tie rod that extends forward of the vehicle body, and an outer end in the vehicle width direction of the tie rod 18 is attached to a tip 8d of the knuckle arm 8c. The inner end of the tie rod 18 in the vehicle width direction is attached to the steering gear unit 16.

  As shown in FIG. 2, the tie rod 18 extends in a plan view so that the tie rod 18 and the vehicle width direction are at an angle α (hereinafter referred to as an inclination angle) when neutral (when the steering is neutral). . This inclination angle α establishes the Ackermann geometry of the front suspension device 1 so that the turning angle of the turning inner wheel is larger than the turning angle on the outer wheel side during steering. As shown in FIG. 3, the tie rod 18 extends obliquely upward outward in the vehicle width direction when viewed from the front, and has an inclination angle β with respect to the horizontal line. By this inclination angle β, the front suspension device 1 has a bump toe-in characteristic, and the bumped turning outer wheel is prevented from facing toe-out.

  Next, the operation of the front suspension device 1 of the present embodiment will be described. As described above, in the double wishbone type front suspension device as in the present embodiment, the lower end of the damper (strut 10) is supported by a portion in the middle of the lower arm 6, so that the input from the road surface is the wheel of the lower arm 6. When acting on the side end, the support position of the damper not following the input serves as a fulcrum, and the vehicle body side end 6d of the lower arm 6 is moved upward or downward according to the principle of leverage, which is the initial input from the road surface. It is thought that the ride comfort is deteriorated at the stage.

  In this respect, in the present embodiment, when the end portion 6d of the lower arm 6 attempts to move up and down relatively with respect to the shaft support portion 28 in the shaft support portion 28, the stopper portion 2442b of the bush 244 contacts the shaft support portion 28, The movement is suppressed. By providing the stopper portion 2442b at the upper and lower ends of the main body portion 2442a, it is not necessary to increase the hardness of the elastic body 2442. Therefore, in this embodiment, the problem specific to the double wishbone type front suspension device in which the lower end of the damper is attached to the lower arm is solved, and the vertical movement of the vehicle body side end portion of the lower arm 6 is suppressed, and the steering stability is improved. The ride comfort can be balanced more effectively.

  As shown in FIG. 5, the stopper portion 2442 b does not necessarily need to be in constant contact with the shaft support portion 28, and the shaft support portion is moved when the end 6 d of the lower arm 6 moves up and down relatively with respect to the shaft support portion 28. If it is configured to abut against 28, a certain effect can be obtained with respect to suppression of vertical movement of the end 6 d of the lower arm 6.

  However, since the space in the vertical direction of the shaft support portion 28 is secured at least by the height of the bush 244, the end surface 2442b ′ of the stopper portion 2442b is connected to the end surface 2441 ′ of the inner cylinder 2441 as shown in FIG. It is desirable to set it substantially flush. By doing so, the stopper portion 2442b can be inserted without being compressed when the end portion 6d of the lower arm 6 into which the bush 244 is press-fitted is inserted into the gap of the shaft support portion 28, and the assembly thereof can be facilitated.

  Further, it is desirable that the end surface 2442b 'of the stopper portion 2442b, which is a contact surface with respect to the shaft support portion 28, is subjected to a process for reducing friction with the shaft support portion 28. By doing so, it is possible to reduce friction between the stopper portion 2442b and the shaft support portion 28 so that the elastic body 2442 can be smoothly deformed in the front-rear direction, and the end portion 6d of the lower arm 6 with respect to the shaft support portion 28 can be obtained. The relative back and forth movement is not hindered due to the contact of the stopper portion 2442b with the shaft support portion 28. Examples of the process for reducing the friction include performing a process for smoothing the end surface 2442b 'and applying a smoothing agent such as various paints to the end surface 2442b'.

  Next, the operation of maintaining the Ackermann geometry and the like by the front suspension device 1 will be described. FIG. 7 is an explanatory diagram for explaining the force and displacement applied to the wheel 17, the suspension arms 4 and 6 and the wheel support member 8 during braking. FIGS. 8A and 8B are explanatory views for explaining the toe-out displacement of the wheel support member 8 during braking.

  First, as shown in FIG. 7, during braking, a braking force F is applied to the wheel 17, this braking force F is transmitted to the wheel support member 8, and a rotational moment force M is applied to the wheel support member 8. The rotational moment force M is transmitted to the upper arm 4 and the lower arm 6, and the transmitted force deforms the bushes 241 to 244 of the shaft support portions 20, 22, 26, 28 on the vehicle body side of the arms 4, 6. . As a result, the upper arm 4 is displaced toward the front of the vehicle body (D1 in the figure), the lower arm 6 is displaced toward the rear of the vehicle body (D2 in the figure), and the wheel support member 8 rotates in the direction as indicated by D3 in the figure. To do.

  When such a rotational displacement D3 occurs in the wheel support member 8, the tip 8d of the knuckle arm 8c for connecting the tie rod is displaced downward and rearward of the vehicle body. For this reason, as shown in FIGS. 8A and 8B, the tie rod 18 is displaced as indicated by the phantom line in the figure due to the displacement of the tip 8d. That is, since the front end portion 8d is displaced downward and rearward of the vehicle body, the inclination angle (α) of the tie rod 18 is reduced, while the length of the tie rod 18 itself does not change, so that the front end portion 8d is lower and rearward of the vehicle body. It will be displaced to the side and also to the outside in the vehicle width direction. That is, because the tie rod 18 is attached to the front end of the vehicle body of the wheel support member 8 and the tie rod 18 is inclined, the wheel 17 is directed toward the toe-out direction during braking. It will move.

  Here, as shown in FIG. 8A, when the lower arm 6 is displaced straight toward the rear of the vehicle body in the longitudinal direction of the vehicle body as shown by the phantom line by the braking force F (see FIG. 7), the wheel of the lower arm 6 The end 6e on the support member 8 side is displaced straight in the vehicle longitudinal direction and is not displaced in the vehicle width direction. Therefore, the wheel support member 8 is displaced as indicated by the phantom line in the figure, and as a result, the wheel 17 moves in the toe-out direction.

  On the other hand, as described with reference to FIG. 6, in this embodiment, the curly portion 2442c on the outer side in the vehicle width direction is provided behind the curly portion 2442c on the inner side in the vehicle width direction. It becomes easy to deform rearward and outward. Accordingly, it is possible to suppress the end portion 6e of the lower arm 5 from being straightly displaced toward the rear of the vehicle body during braking and to move the vehicle rearwardly outward, thereby suppressing toe-out during braking.

  Furthermore, in the present embodiment, the centers of the two currant portions 2442c form an angle γ with the swing center line B in the front-rear direction of the vehicle body, and are set on a line C that passes through the axis of the inner cylinder 2441. Accordingly, the end 6d of the lower arm 6 is easily displaced in the direction of the line C in FIG. In addition, as described with reference to FIG. 6, in the present embodiment, the stopper portion 2442b is formed in a straight strip shape across the inner cylinder 2441 in a plan view, and is substantially parallel to the swinging center line B. 6, the bush 244 is difficult to deform in the longitudinal direction of the vehicle body. As a result, the end 6d of the lower arm 6 depends on the direction of the line C in FIG. It becomes easier to displace.

  For this reason, as shown in FIG.8 (b), the edge part 6d is displaced to the vehicle width direction outer side while it is displaced to the vehicle body rear side. Then, the end portion 6c on the vehicle body front side of the lower arm 6 is also displaced so as to be pulled outward in the vehicle width direction due to such displacement of the end portion 6d. Accordingly, the end portion 6e of the lower arm 6 on the wheel support member 8 side is displaced rearward in the vehicle longitudinal direction and displaced outward in the vehicle width direction.

  If the angle γ between the center of the two curly portions 2442c and the swing center line B in the longitudinal direction of the vehicle body and the inclination angle α of the tie rod 18 in the neutral position are substantially matched, As shown, the wheel support member 8 generally moves outward in the vehicle width direction. In this way, toe-out during braking of the wheel 17 can be suppressed. The angle γ and the inclination angle α are set to 25 degrees to 35 degrees, for example.

  When the lower arm 6 is displaced, the elastic body of the bush 243 of the shaft support portion 26 on the front side of the vehicle body is set to a relatively small compliance with respect to the elastic body 2442 of the bush 244 of the shaft support portion 28 on the rear side of the vehicle body. Rotation also occurs with the front shaft support portion 26 as a substantial center. By this rotation, the displacement of the end portion 6e toward the rear of the vehicle body due to the displacement of the lower arm 6 toward the rear of the vehicle body (see FIG. 7) is suppressed, and the rotational displacement D3 (see FIG. 7) of the wheel support member 8 can also be suppressed. . As a result, toe-out during braking of the wheels 17 can be suppressed.

  Further, when the angle γ is set to 25 degrees to 35 degrees, the amount of deformation of the bush 244 in the longitudinal and lateral directions of the bush 244 is not so much larger than when the angle γ is set near 0 degrees or 90 degrees. Steering stability can be improved.

<Other embodiments>
In the above embodiment, for the elastic body 2442 of the bush 244, the main body portion 2442a and the stopper portion 2442b are integrally formed of the same material, but the hardness may be different between the main body portion 2442a and the stopper portion 2442b. If these hardnesses can be set individually, it is possible to perform tuning that more effectively realizes both steering stability and riding comfort while suppressing the vertical movement of the vehicle body side end portion 6d of the lower arm 6.

  In order to make the main body portion 2442a and the stopper portion 2442b have different hardnesses, for example, it is simplest to make them different members. FIG. 9 is a view showing an example of a bush in which the main body portion 2442a and the stopper portion 2442b are formed of different members. FIG. 9A is an exploded cross-sectional view, and FIG. 9B is a cross-sectional view after assembly. In the bush 244 'shown in the drawing, an inner cylinder 2441 is composed of three parts 2441b, 2441c, and 2441d, and a stopper portion 2442b, a main body portion 2442a, and a stopper portion 2442b are fixed to each other. An outer cylinder 2443 is further fixed to the outer periphery of the main body 2442a.

  As shown in FIG. 9A, the part 2441b is fitted to the upper part of the part 2441c and the part 2441d is fitted to the lower part of the part 2441c to complete the inner tube 2441, and at the same time, stopper portions are provided at the upper and lower ends of the main body 2442a. 2442b will be formed respectively. When the orientation of the stopper portion 2442b is simply aligned, a groove or the like is provided in each of the fitting portion between the parts 2441b and 2441c and the fitting portion between the parts 2441d and 2441c. The fitting position at the time of alignment is defined, and the direction of the stopper portion 2442b can be easily aligned.

  In the example of FIG. 9, since the stopper portion 2442b and the main body portion 2442a are separate members, the materials can be individually selected and the hardness can be different. By preparing a plurality of types of hardness for each of the stopper portion 2442b and the main body portion 2442a, variations of these combinations increase, and bushings having various elastic characteristics can be obtained. Moreover, it is also possible to add a stopper part with respect to the existing bush without a stopper part. In addition, even if it is a case where the main-body part 2442a and the stopper part 2442b are made into a separate member as shown in FIG. 9, it cannot be overemphasized that the thing with the same hardness may be used.

1 is a perspective view showing a front suspension device 1 for an automobile according to an embodiment of the present invention. FIG. 3 is a plan view of the right front wheel side of the front suspension device 1 as viewed from above the vehicle body. FIG. 3 is a front view of the right front wheel side of the front suspension device 1 as viewed from the front of the vehicle body. 4A is an external perspective view of the bush 244, FIG. 4B is a cross-sectional view taken along line YY in FIG. 4A, and FIG. 4C is a cross-sectional view taken along line ZZ in FIG. FIG. 3 is a sectional view taken along line XX in FIG. 2. 2 is a plan view of a peripheral structure of a lower arm 6 of the front suspension device 1. FIG. It is explanatory drawing for demonstrating the force and displacement which are added to the wheel 17, the suspension arms 4, 6 and the wheel support member 8 at the time of braking. (A) And (b) is explanatory drawing for demonstrating the toe-out displacement of the wheel support member 8 at the time of braking. It is a figure which shows other embodiment of the bush.

Explanation of symbols

1 Front suspension device 2 Suspension cross member 4 Upper arm 6 Lower arm,
8 Wheel support member 10 Strut 12 Damper 14 Coil spring 16 Steering gear unit 18 Tie rods 20, 22, 26, 28 Shaft support portions 241 to 244 Bushing 2411 Inner cylinder 2422 Elastic body 2422a Main body portion 2422b Stopper portion 2422b ′ End surface (contact surface)
2422c Currant 2423 outer cylinder

Claims (8)

An upper arm and an A-type lower arm constructed between the vehicle body and the wheel support member;
A damper attached to the vehicle body at the upper end and to the A-type lower arm at the lower end;
In the double wishbone type front suspension device with
The vehicle body is
The vehicle body includes a front shaft support portion and a rear shaft support portion that are provided apart from each other in the front-rear direction of the vehicle body and support the two vehicle body side ends of the A-type lower arm, respectively.
The front shaft support portion pivotally supports the A-type lower arm on the vehicle body via a first bush having an axial center set in the longitudinal direction of the vehicle body,
The rear shaft support portion pivotally supports the A-type lower arm on the vehicle body via a second bush having an axial center set in the vertical direction of the vehicle body,
The second bush is
An inner cylinder having an axial center set in the vertical direction of the vehicle body, and an elastic body provided around the inner cylinder,
The elastic body is
A main body interposed between the inner cylinder and an end of the A-type lower arm;
A currant portion drilled in the main body in a direction parallel to the axis of the second bush;
A stopper portion that protrudes at the upper and lower end portions of the main body portion and suppresses the vertical movement of the end portion of the A-type lower arm with respect to the rear shaft support portion by contacting the rear shaft support portion,
A front suspension device comprising:   2. The front suspension device according to claim 1, wherein the stopper portion extends on an axial center line of the first bush in the front shaft support portion in a plan view. The front suspension device is
A front suspension device for an automobile, comprising: a front-mounted steering gear unit; and a pair of tie rods extending outward in the vehicle width direction and obliquely forward and connecting the steering gear unit and the wheel support member,
The stopper portion extends in the front-rear direction of the vehicle body,
Two of the currant portions are provided on both sides of the stopper portion, the curly portion on the outer side in the vehicle width direction is provided on the rear side of the curly portion on the inner side in the vehicle width direction, and the two currant portions are 2. The front suspension apparatus according to claim 1, wherein the front suspension apparatus is provided on a line that forms a predetermined angle with the longitudinal direction of the vehicle body in a plan view. The predetermined angle is
4. The front suspension device according to claim 3, wherein the front suspension device substantially coincides with an angle formed by the tie rod when neutral and a vehicle width direction in a plan view. The stopper portion has a contact surface that contacts the rear shaft support portion,
The front suspension device according to any one of claims 1 to 4, wherein the contact surface is processed to reduce friction.   The front suspension device according to any one of claims 1 to 5, wherein an end surface of the stopper portion is set substantially flush with an end surface of the inner cylinder.   The front suspension device according to any one of claims 1 to 6, wherein the stopper portion is a separate member from the main body portion.   The front suspension device according to any one of claims 1 to 7, wherein the stopper portion and the main body portion have different hardnesses.

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