JPH01297315A - Stretching device for vehicle - Google Patents

Abstract

PURPOSE:To compact a gas spring mechanism by providing a suspension arm also served as spring and a gas spring mechanism wherein the volume of compressed gas is changed according to the relative displacement of its rod against a cylinder so as to support elastically a vertical load. CONSTITUTION:In a stretching device 1, a tyre 10, and a hub carrier 3 provided with the axle shaft 9 of the tyre are vertically displaced by the input form road surface while a vehicle is driven. Then a suspension arm 3 also served as spring which has its free end 2b turnably provided on the hub carrier 3 via a ball joint 8 expands and contracts vertically. And the rod 15 of a gas spring mechanism 4 the lower end of which is connected to the hub carrier 3 is relatively displaced in the vertical direction inside a cylinder 14 at the same time; or, if the rod 15 is stuffed into the cylinder 14, then its air chamber 13 is compressed and resiliency of gas increases. A piston portion 19 is displaced inside an oil chamber 12 at the same time and the displacement of the rod 15 is damped at a damping force generating portion 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle suspension system used in a suspension mechanism of an automobile, an accompanying vehicle, or the like.

[Prior art] Gas spring devices used in automobile suspensions are
For example, as seen in Japanese Unexamined Patent Publication No. 60-80920, it has a cylinder and a rod inserted movably in the axial direction of the cylinder. A compressed gas such as nitrogen is stored inside the cylinder, and the repulsive force of the gas urges the rod in a direction to protrude from the cylinder.

This gas spring device is placed between the wheel side member and the vehicle body side member, and the volume of compressed gas changes depending on the relative position of the rod with respect to the cylinder, and the vertical load is elastically reduced due to the repulsive force of the gas. It is now supported by Therefore, if the pressure of gas sealed in is made high enough, it is possible to support the load only with this gas spring device.

In addition, in the above gas spring device, by storing an appropriate amount of hydraulic oil inside the cylinder and providing an orifice at a location where the oil flows with the relative movement of the rod,
A so-called hydropneumatic suspension, which is an oil-filled gas spring device that can damp the reciprocating motion of the rod, has also been put into practical use. In the hydropneumatic suspension, a desired damping force can be obtained by appropriately setting the orifice opening amount, and the spring constant can also be changed by changing the number of air chambers that act as gas springs.

Therefore, by combining it with a sensor that detects the running condition of the vehicle and the unevenness of the road surface, it is possible to use it to adjust the damping force and spring constant according to the situation.

[Problems to be Solved by the Invention] This type of gas spring device needs to support a large load applied to the vehicle body, etc., and the space for accommodating the gas spring device is limited, so it must be constructed compactly. For this reason, it is necessary to increase the gas filling pressure inside the cylinder. However, in order to increase the gas sealing pressure, the pressure walls of the cylinder etc. must be made thicker, which increases the size and weight of the device. Further, since the sealing material provided at the sliding portion between the cylinder and the rod must be made for high pressure, the sliding resistance of the rod becomes considerably large. As a result, problems such as poor response to minute vibrations arise.

On the other hand, suspension arms (links) such as lower arms and upper arms used in well-known independent suspension mechanisms of automobiles are used in combination with suspension coil springs, leaf springs, and the like.

Furthermore, a shock absorber is also used to dampen the vertical movement of the arm. Therefore, this type of suspension system not only requires a spring dedicated to the suspension, but also requires the use of a spring with a large spring constant in order to support the load with this spring alone.

Therefore, an object of the present invention is to provide a suspension system for a vehicle in which the internal pressure of the gas spring mechanism can be lowered and the gas spring mechanism can be made more compact, and the suspension arm can also serve as a suspension spring. .

[Means for Solving the Problems] In order to achieve the above object, the vehicle suspension system of the present invention has F.
The suspension arm is made of RP and has a fixed end fixed to the vehicle body side and a free end connected to a wheel side member, and a cylinder and a rod inserted movably in the axial direction of the cylinder. The cylinder is equipped with a gas spring mechanism in which compressed gas is accommodated and the volume of the compressed gas changes as the rod moves relative to the cylinder, and the vertical load is transferred between the gas spring mechanism and the FRP spring. It is designed to be elastically supported by both the dual-purpose suspension arm.

[Operation] When the wheel moves up and down with respect to the vehicle body, the suspension arm that also serves as a spring is bent in the same direction, and the rod and cylinder of the gas spring mechanism move relative to each other, thereby buffering the up and down movement of the wheel. The suspension arm has a function as a link supporting a wheel-side member like a conventional lower arm or upper arm, and also functions as a suspension spring. Since the vertical load applied to the suspension device is supported by the spring-cum-suspension arm and the gas spring mechanism, the load on the gas spring mechanism is reduced accordingly, making it possible to reduce the cylinder internal pressure. Furthermore, if the cylinder internal pressure is kept the same as before, the volume of gas and the cross-sectional area of the rod may be small.

[Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The independent suspension system 1 for an automobile shown in FIG. ing. A base end portion, that is, a fixed end 2a of the suspension arm 2 is fixed in a cantilevered manner to a frame 5, which is a member on the vehicle body side, using fixing parts 6 such as bolts.

The suspension arms 2 are each made of a well-known matrix resin reinforced with unidirectional continuous reinforcing fibers mainly along the longitudinal direction, and are formed into a tapered shape such that the plate thickness on the free end 2b side gradually decreases. That is, it is an FRP taper leaf.

With such a tapered leaf, when the arm 2 bends in the vertical direction, the stress in each part in the longitudinal direction approaches equalization, and a large deflection can be obtained even with a short span, which is also advantageous in terms of weight reduction. . This arm 2 may be of a stacked leaf spring type in which a plurality of springs are stacked in the thickness direction.

The hub carrier 3 is provided at the free end 2b of the suspension arm 2 by a ball joint 8 so as to be pivotable about the vertical y-axis.

In the case of a drive wheel, the axle 9 provided on the hub carrier 3 is rotated by a drive shaft (not shown).

A tire 10 is attached to the axle 9 via a hub (not shown).

On the other hand, as conceptually shown in FIG. 2, the gas spring mechanism 4 includes a cylinder 14 having an oil chamber 12 and an air chamber 13 therein, a rod 15, and the like. The oil chamber 12 and the air chamber 13 are separated by a bellows-like expandable partition member 17, for example.
completely separated by. Cylinder 14 in the illustrated example
has an inner cylinder 18 concentrically therein, and this inner cylinder 18
The rod 15 relatively reciprocates in the axial direction along. The rod 15 can rotate about an axis relative to the cylinder 14. A piston portion 19 provided on the rod 15 is provided with a damping force generating portion 20 having an orifice. The interior of the oil chamber 12 is filled with hydraulic oil. The inside of the air chamber 13 is filled with compressed inert gas such as nitrogen. In addition,
By connecting a hydraulic unit to the oil chamber 12, the oil chamber 1
The vehicle height may be adjustable by allowing oil to be taken in and out of the vehicle. Alternatively, the damping force generating section 20 may be provided with a valve body driven by an actuator, and the damping force may be switched by making the orifice opening amount variable.

The upper end side of the gas spring mechanism 4 in the drawing is attached to the frame 5. The lower end side of the gas spring mechanism 4 in the diagram is the hub carrier 3
is connected to. Therefore, the hub carrier 3 is the rod 15
It can rotate around the y-axis as a unit.

In the suspension system 1 having the above configuration, when the tire 10 and the hub carrier 3 move in the vertical direction due to vertical input from the road surface while driving, the spring arm 2 bends in the vertical direction, and the rod of the gas spring mechanism 4 15 can relatively move in the vertical direction, thereby absorbing input from the road surface. More specifically, when the rod 15 moves in the direction in which it is pushed into the cylinder 14, the air chamber 1 is expanded by a volume corresponding to the amount by which the rod 15 is pushed into the cylinder 14.
3 is further compressed, and the repulsive force of the gas increases. At the same time, the piston section 19 moves within the oil chamber 12, and oil flows into the orifice of the damping force generating section 20, causing the rod 1
5 movements are damped. Conversely, when the rod 15 moves in the direction of protruding from the cylinder 14, the cylinder 14
The volume of the air chamber 13 increases by the amount that the rod 15 is pulled out from inside. At this time as well, the movement of the rod 15 is damped by the oil flowing into the orifice of the damping force generating section 20.

In this way, in the suspension system 1 of this embodiment, the load in the vertical direction is distributed and supported by the spring arm 2 and the gas spring mechanism 4, so when the load is supported only by the gas spring mechanism 4, Compared to this, it has the following advantages.

Here, the load applied to the rod 15 of the gas spring mechanism 4 is W
, the radial cross-sectional area of the rod 15 is A, the gas volume is V, the cylinder internal pressure is P, and the gas spring constant is k, the following equation holds true.

k-WA/V-PA2/V ,,,The overall suspension system is Since there is no difference in the amount of vertical deflection, the spring arm 2 and the gas spring mechanism 4
When used in combination, the spring constant decreases depending on the load sharing ratio compared to the case where the gas spring mechanism 4 is used alone. For example, if the load is shared in half by the arm 2 and the gas spring mechanism 4, the spring constant of the gas spring mechanism 4 will be 1/2, and if the load is shared by the gas spring mechanism 4 in 1/3, then the spring constant of the gas spring mechanism 4 will be 1/2. 1/3 is enough for the spring constant.

As is clear from the above equation 0, if the spring constant k is 1/2
Then, if the rod cross-sectional area A and the gas volume V are constant, the cylinder internal pressure P may be 1/2. On the other hand, when the cylinder internal pressure P is kept constant, the rod cross-sectional area A only needs to be 1/2, and the gas volume V only needs to be 1/2. Spring constant k is 1/3
If the rod cross-sectional area A and the gas volume V are constant, the cylinder internal pressure P may be 1/3. If the spring constant k is 1/3 and the cylinder internal pressure P is constant, the rod cross-sectional area A only needs to be 1/3, and the gas volume V also needs to be 1/3. These are just examples, and the cylinder internal pressure P, rod cross-sectional area A, and gas volume V can be varied as required. Further, the ratio of load sharing between the spring arm 2 and the gas spring mechanism 4 can be varied as necessary.

When the cylinder internal pressure P is reduced as described above, the wall thickness of the cylinder 14 can be made thinner, and the pressure of the sealing material in the sliding portion between the cylinder 14 and the rod 15 can be lowered, making sealing easier. becomes. Furthermore, in the case of a gas spring mechanism with a vehicle height adjustment function that allows oil to be taken in and out of the oil chamber 12 by connecting a hydraulic unit, there is an advantage that the burden on the hydraulic pump is lightened. On the other hand, if the gas volume V or the rod cross-sectional area A is reduced, the cylinder 14 or the rod 15 can be made more compact and lighter.

In addition, the spring arm 2 made of FRP has a much lower Young's modulus than that of steel, and can have a sufficiently large amount of deflection, allowing the hub carrier 3 to move up and down with a large vertical stroke. . Since this arm 2 also serves as a suspension spring, there is no need to separately provide a suspension spring such as a coil spring, and the storage space can be reduced.

In addition, compared to the case of using conventional suspension coil springs, the amount of protrusion in the vertical direction and vehicle width direction is smaller, and the amount of protrusion toward the engine room is also smaller, so it is useful for design and aerodynamic reasons. This is advantageous when you want to lower the engine speed, and you can use more space in the engine compartment, which has tended to become narrower as automobiles become more FF (front engine, front drive) and four-wheel drive.

Note that FIG. 3 shows a second embodiment of the present invention, in which a hub carrier 3 is attached via a vertically long U-shaped intermediate holder 22. As shown in FIG. The free end 2b of the arm 2 is pivotally connected to the lower end of the intermediate holder 22 by a horizontal shaft 23, and the gas spring mechanism 4 is attached to the upper end of the intermediate holder 22.

The hub carrier 3 is vertically y relative to the intermediate holder 22.
It is rotatably supported around the 'axis. Also in this embodiment, the load in the vertical direction is elastically supported by both the spring arm 2 and the gas spring mechanism 4.

In the third embodiment shown in FIG. 4, a hub carrier 3 is rotatably supported by a lower arm 2 and an upper arm 25 via ball joints 26 and 27. The upper arm 25 is made of FRP like the lower arm 2, and its fixed end 25a is fixed to the frame 5. Upper arm 25
It is also preferably formed into a tapered shape such that the plate thickness on the free end 25b side is reduced. A gas spring mechanism 4 is provided between the lower arm 2 and the vehicle body frame 5. In this case, in order to avoid interference with the gas spring mechanism 4, the upper arm 25 is bifurcated into two pieces as shown in FIG. 5 or 6. lower arm 2
may be divided into one sheet as shown in FIG. 5 or two sheets as shown in FIG. The upper and lower arms 2 and 25 are both fixed to the frame 5.

FIG. 7 shows a fourth embodiment of the present invention. In this embodiment, each free end 2b of the lower arm 2 and the upper arm 25 is
, an intermediate holder 22 is pivotally attached to the 25b side by a horizontal shaft 30° 31, and a hub carrier 3 is attached to this intermediate holder 22.
is mounted so that it can rotate freely around the y' axis. In this case, in order to avoid interference with the gas spring mechanism 4, it is preferable that the upper arm 25 be bifurcated as in the example shown in FIG. 5 or 6. The lower arm 2 may be divided into one piece as shown in FIG. 5 or two pieces as shown in FIG. 6.

Note that one of the upper and lower spring arms 2.25 may be made of FRP, and the other may be made of steel.

[Effects of the Invention] According to the present invention, it is possible to reduce the cylinder internal pressure of a gas spring mechanism used in a suspension, reduce the gas volume, rod cross-sectional area, etc., and thereby achieve compactness. Further, since the FRP suspension arm also serves as a suspension spring, there is no need to separately provide a coil spring or the like.

[Brief explanation of the drawing]

FIG. 1 is a front view of a suspension system showing a first embodiment of the present invention;
2 is a sectional view of the gas spring mechanism in the suspension system shown in FIG. 1, FIG. 3 is a front view of the suspension system showing a second embodiment of the present invention, and FIG. 4 is a third embodiment of the present invention. FIG. 5 is a perspective view of the suspension device shown in FIG. 4, FIG. 6 is a perspective view of a modification of the lower arm, and FIG. 7 is a fourth embodiment of the present invention. FIG. 3 is a front view of the suspension device. DESCRIPTION OF SYMBOLS 1... Suspension device, 2... Suspension arm also serving as a spring, 2a... Fixed end, 2b... Free end, 3...
Hub carrier, 4... Gas spring mechanism, 5... Frame (body side member), 10... Tire (wheel), 14
...Cylinder, 15...Rod, 25...Upper arm (suspension arm that also serves as a spring). Applicant's agent Patent attorney Takehiko Suzue Figure 1 ↓ Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] The suspension arm is made of FRP and has a fixed end fixed to the vehicle body and a free end connected to a wheel side member, and a cylinder and a rod inserted movably in the axial direction of the cylinder. The cylinder is equipped with a gas spring mechanism in which compressed gas is accommodated and the volume of the compressed gas changes as the rod moves relative to the cylinder, and the vertical load is transferred between the gas spring mechanism and the FRP. A vehicle suspension system characterized by being elastically supported by both a spring and a suspension arm.