JPS63106119A - Wheel suspension device for automobile - Google Patents

Abstract

PURPOSE:To enhance the longitudinal compliance and caster rigidity upon braking with the use of a double wishbone type wheel suspension device, by coupling the base ends of upper and lower control arms to upper and lower support arms projected from a vertical support shaft. CONSTITUTION:Moments are effected to upper and lower control arms 6, 7 by force exerted to an axle 1 from the ground surface, through a knuckle 2. Thereby, upper and lower support arms 13, 14 of a cylindrical shaft 12 are subjected to rotating moments in the same direction or opposite directions during rectilinear advance or upon braking, and therefore, the motions of both control arms 6, 7 are controlled. That is, when the wheel 1 goes over a projection on the road surface, both control arms 6, 7 are easily inclined rearward by that force through a cylindrical shaft 12 so that a large longitudinal compliance may be obtained. Upon braking, the moments of the upper and lower control arms 6, 7 are in opposite directions so that they are canceled out each other to enhance the caster rigidity.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Application Field The present invention relates to an automobile wheel: a bridge system, and in particular to a pair of upper and lower control arms whose tips are connected to a knuckle that supports the wheel; This invention relates to an improvement of a lower control arm in which each base end is pivoted to the vehicle body at two locations, front and rear, so as to be able to swing vertically.

(2) Prior Art Such a wheel suspension system is widely known as a double wishbone type (see, for example, Japanese Patent Publication No. 44-28123).

(3) Problems to be Solved by the Invention In the conventional wheel suspension system, the base ends of the upper control arm and the lower control arm are each pivotally connected to a horizontal shaft fixed to the vehicle body via an elastic member. Therefore, the longitudinal compliance and caster rigidity during braking are influenced by the spring constants of these elastic members.

In general, it is necessary to increase the longitudinal compliance of the wheel suspension system in order to minimize the transmission of shock to the vehicle body when the wheels go over a protrusion on the road surface, and to ensure the straightness of the wheels during braking. Therefore, it is necessary to increase the caster rigidity of the wheel suspension system.

However, in the conventional wheel suspension system, if the longitudinal compliance is set thick (preferably the spring constant of the elastic member is set small), the caster rigidity decreases, impairing the straightness of the wheel, and when braking. Thicken the caster rigidity (
If the spring constant of the elastic member is preferably set to a large value, the compliance in the longitudinal direction decreases, resulting in poor riding comfort, so it is difficult to achieve both compliance in the longitudinal direction and caster rigidity during braking.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel suspension system that can satisfy both longitudinal compliance and caster rigidity during braking.

B0 Structure of the Invention (1) Means for Solving Problems In order to achieve the above object, the present invention provides a pair of upper support arms and a support shaft supported by the vehicle body via an elastic member and extending in the vertical direction. The present invention is characterized in that a lower support arm is provided in a protruding manner, and the front or rear portions of the base ends of the upper control arm and the lower control arm are respectively connected to the upper support arm and the lower support arm.

(2) Action When a load is applied to the center of the knuckle in the longitudinal direction of the vehicle, the upper control arm and lower control arm each apply rotational moment in the same direction to the support shaft, so the total rotational moment received by the support shaft is large. It is. On the other hand, when braking force is applied to the tire grounding point, the upper control arm and lower control arm apply rotational moments to the support shaft in opposite directions, so these moments cancel each other out, resulting in a total rotational moment applied to the support shaft. It becomes zero or very small. Therefore, even if the spring constant of the elastic member supporting the support shaft is set to be small in order to obtain a large longitudinal compliance, a large caster rigidity can be ensured during braking.

(3) Examples Examples of the present invention will be described below with reference to the drawings. First, starting with the first embodiment, in FIG. 1, a knuckle 2 for supporting a wheel l is connected to a spindle 3 that supports the wheel 1 via a bearing (not shown), and a spindle 30 that extends upward and downward from the base end of the spindle 30. Bifurcated arms that branch out and extend 4.4
The tips of an upper control arm 6 and a lower control arm 7 are connected to these bifurcated arms 4, 4 via ball joints 5.5', respectively.

Then, the caster of the wheel 1 is determined by the inclination of the straight line connecting the centers of both ball joints 5, 5'.

The upper control arm 6 branches into a pair of front and rear arm portions 6f and 6r on the base end side, and the lower control arm 7 also branches into a pair of front and rear arm portions 7f and 7r on the base end side, and the rear arm portion 6r. .

7r is pivotally connected to pivot shafts 8 and 9 that are fixed to the vehicle body B and extend in the longitudinal direction thereof via elastic members 10.1) so as to be able to swing vertically, and both control arms 6.7 are supported by suspension springs (not shown). It is fired downward.

A cylindrical shaft 12 serving as a support shaft is disposed adjacent to the front of the front arm portions 6f and 7f, and the cylindrical shaft 12 has both ends fixed to the vehicle body B and has an elastic member 18 attached to a pivot shaft 17 extending in the vertical direction.
18' (see FIG. 3),
Further, a pair of upper and lower support arms 13 and 14 that protrude rearward are integrally formed on the outer surface of the cylinder shaft 12, and a front arm portion 6f is attached to these.

7f are connected via ball joints 15 and 16, respectively.

Here, the effective length of the upper control arm 6 is A1
, the effective length of the lower control arm 7 is Az, the front of the upper control arm 6.

The distance between the base end support points of the rear arms 6f and 6r is Br, and the front and rear arms 7r and 7 of the lower control arm 7 are
The distance between the base end support points of r is BZ, the effective length of the upper support arm 13 is C1, the effective length of the lower support arm 14 is Cz, the ground height of the upper control arm tip connection part is Hl, the lower control arm tip connection When the height above ground of the section is defined as H2, these dimensions are set so that the following equation holds true.

As shown in FIG. 2, a pair of elastic stoppers 19 and 20 fixed to the vehicle body B are arranged facing each other with a predetermined gap on both left and right side surfaces of the upper support arm 13. The rotation angle of the cylinder shaft 12 is limited by the contact between the cylinder shaft 20 and the support arm 13.

In the figure, reference numeral 21 denotes a knuckle arm provided on the knuckle 2, which is connected to a steering mechanism when the wheel 1 is a front wheel, and supported by the vehicle body when the wheel 1 is a rear wheel. Arrow A indicates the front of the vehicle.

Next, the operation of this embodiment will be explained.

First, in FIGS. 4 and 5, while the vehicle is running, wheel 1
Assume that the road surface G passes through a protrusion 22 such as a pebble on the road surface G. i When the wheel weight climbs the protrusion 22, the protrusion 22
The component force F of the force applied to the knuckle 2 toward the rear of the vehicle is decomposed into parallel components Fl and F2 by the bifurcated arms 4, 4, and is applied to the upper control arm 6 and lower control arm 7.
These act on the tips of both control arms 6.
Since ゜7 receives moments M+ and Mz toward the rear of the vehicle, the cylinder shaft 1 is deformed while deforming the elastic members 10.1) at each base end.
Rotation moment Ms in the same direction on both supporting arms 13 and 14 of 2
, give Ma. Therefore, the total rotational moment M 3 +M m that the cylinder shaft 12 receives is large, and the elastic members 18, 18' that support the cylinder shaft 12 can be easily deformed by receiving a large torsional force, so that both the upper and lower control arms 6 .7 can relatively easily tilt the vehicle toward the rear according to the component force F. In this way, the wheel suspension system is given a large degree of compliance in the longitudinal direction, and the impact force from the protrusion 22 can be alleviated and prevented from being transmitted to the vehicle body.

The movement of the front wheel 1 up and down as it passes through the protrusion 22 is controlled by the upper control arm 6 and the lower control arm 7 connected to their respective pivots 8, 9 and ball joints 15.
It is allowed to swing up and down around 16.

Next, in FIGS. 6 and 7, it is assumed that the wheels 1 are braked by the operation of a brake device (not shown) while the vehicle is running. When braking is applied to the wheel l, the frictional braking force f acting on the front wheel 1 from the road surface G applies a forward moment m to the upper control arm 6 and a rearward moment mz to the lower control arm 7. Control arm 6 is cylinder shaft 1
6, a counterclockwise rotational moment m is applied to the upper support arm 13 of No. 2, and in contrast, the lower control arm 7
is the clockwise moment m4 on the lower support arm 14 of the cylinder shaft 12.
Add. In this way, since the rotational moments m, , m, applied to both support arms 13 and 14 are in opposite directions, they cancel each other out via the cylinder axis 12, and by the establishment of the above equation (1), the cylinder axis The total rotational moment acting on 12 becomes approximately zero. As a result, the upper control arm 6 and the lower control arm 7 are prevented from moving forward or backward, and the knuckles 2
can prevent displacement. Therefore, even if the tire rides on a protrusion during braking, it is possible to obtain the same longitudinal compliance as when not braking. This is advantageous when giving priority to riding comfort.

Next, a second embodiment will be explained.

The second embodiment has the same structure as the first embodiment except that the dimensions of each part are set so that the following equation holds.

A1 ・CI A2 ・C2B I
B! To explain the operation of this embodiment, when the wheel 1 passes a protrusion 2 such as a pebble on the road surface G, the total rotational moment that the cylinder shaft 12 receives is large (and therefore large), as in the first embodiment. Compliance is provided.Furthermore, when the brake system is activated to apply braking to the wheels 1 while the vehicle is running, the total rotational moment acting on the cylinder shaft 12 becomes small.Furthermore, this total rotational moment causes the upper control Even if the arm 6 and the lower control arm 7 move, the amount of movement of each arm is the same because equation (2) holds true. Therefore, the caster angle does not change, that is, a large caster rigidity can be obtained.

This is advantageous when giving priority to straightness.

C6 Effects of the Invention As described above, according to the present invention, a pair of upper support arms and a lower support arm are provided protruding from a support shaft that is supported by the vehicle body via an elastic member and extends in the vertical direction, and these upper support arms and Since the front or rear parts of the base ends of the upper control arm and lower control arm are connected to the lower support arm, when a load is applied to the center of the knuckle in the longitudinal direction of the vehicle, there is a large rotation from both control arms to the support shaft. By applying a moment and making it easier for the support shaft to rotate, greater longitudinal compliance of the wheel suspension system can be obtained, and when braking force is applied to the tire contact point, the total rotation applied from both control arms to the support shaft can be increased. Since the moment is zero or small and the support shaft hardly rotates, the movement of the wheel suspension system in the longitudinal direction of the vehicle can be reduced, which improves shock absorption when driving on uneven roads and straight-line performance when braking. can satisfy both.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of the entire wheel suspension system of the present invention, and FIGS. 4 and 5 are plan views and side views illustrating the action when the wheels climb a protrusion on the road surface, and FIGS. 6 and 7 are plan views and side views illustrating the action during braking, respectively. FIG. B...Car body L...Wheel, 2...Knuckle, 3...Spindle, 4゜4'...Forked arm, 5,5'...Ball joint, 6...Upper control Arm, 6f, 6r
···Before. Rear arm section, 7...lower control arm, 7r.

Claims (3)

[Claims] (1) An automobile wheel suspension system in which the base ends of a pair of upper and lower control arms, whose tips are connected to the knuckles that support the wheels, are pivoted to the vehicle body at two locations in the front and back so that they can swing vertically. A pair of upper support arms and a lower support arm are provided to protrude from a support shaft that is supported by the vehicle body via an elastic member and extends in the vertical direction, and an upper control arm and a lower control arm are attached to these upper support arms and lower support arms. A wheel suspension system for an automobile, characterized in that the front or rear portions of each base end are connected to each other. (2) In what is stated in claim (1),
The effective length of the upper control arm is A_1, the effective length of the lower control arm is A_2, the distance between the front and rear support points on the base end of the upper control arm is B_1, the distance between the front and rear support points on the base end of the lower control arm is B_
2. When the effective length of the upper support arm is C_1, the effective length of the lower support arm is C_2, the ground clearance of the upper control arm tip connection part is H_1, and the ground clearance of the lower control arm tip connection part is H_2. , the following formula (A_2・C_2/B_2)/(A_1・C_1/B_
1) A wheel suspension system for an automobile that satisfies ≒H_2/H_1. (3) In what is stated in claim (1),
The effective length of the upper control arm is A_1, the effective length of the lower control arm is A_2, the distance between the front and rear support points on the base end of the upper control arm is B_1, the distance between the front and rear support points on the base end of the lower control arm is B_
2. When the effective length of the upper support arm is C_1 and the effective length of the lower support arm is C_2, the following formula A_1・C_1/B_1≒A
An automobile wheel suspension system that satisfies _2・C_2/B_2.