JPH02182512A - Pneumatic suspension - Google Patents

Abstract

PURPOSE:To offset a bending moment to be applied onto a strut when a suspension is mounted on a vehicle by offsetting the center line of the large diameter side of a rolling diaphragm toward the outside of a vehicle relative to the center line of the small diameter side of it. CONSTITUTION:A pneumatic suspension is so constructed that a rolling guide 16 is provided under an outer shell 14 through an air chamber 15. The large diameter side 171 and small diameter side 172 of a rolling diaphragm 17 are fitted closely onto the downward tube section 141 of the outer shell 14 and the upward tube section 161 of the rolling guide 16, respectively. In this case, the center line Y of the large diameter side 171 is offset by a specified amount of offset l1 toward the outside of a vehicle relative to the center line Y' of the small diameter side. When the suspension is mounted on the vehicle, the other bending moments M2 and m are applied in it in such a direction as the bending moment M1 accompanying a wheel reactional force is offset. Thus lateral forces a and b generated due to the bending moment M1 and applied onto a piston 22 and rod guide 23 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air suspension for a vehicle, and particularly to an air suspension that combines a strut damper and an air spring.

(Prior Art) A strut type air suspension is used which is configured to transmit vehicle weight to the wheels via air springs and absorb vibrations from the wheels using the air springs and strut dampers.

This type of air suspension has the advantage of being able to keep the spring constant relatively low and having excellent vibration absorption characteristics. However, in this type of strut-type air suspension, a bending moment is applied to the strut body when it is installed on a vehicle, so countermeasures are often required to counteract this.

For example, in the air suspension structure disclosed in Japanese Patent Application Laid-Open No. 57-110517, as shown in FIG.
and a rolling seal 4, and is configured to attenuate and absorb vibrations transmitted to the strut body 5 from the wheel 6 side by the movement of the air chamber 1 and the strut.

In particular, here, the upper tank 2 and the lower tank 3 are held coaxially, and the center line of both tanks is X = -X- The structure is such that it is offset to the outside of the vehicle. This creates a moment M' that cancels out the bending moment M applied to the strut due to the reaction force from the wheels.
It is configured to cancel the lateral force applied to the piston part 7 and the rod guide part 8.

(Problem to be Solved by the Invention) By the way, when the strut body 5 is made eccentric from the center line x--x' of the lower tank 3 as shown in FIG. 4, in order to prevent interference between the strut body 5 and the lower tank 3, , the diameter of the lower tank 3 must be increased, and as a result, the outer diameter of the diaphragm (rolling seal 4) also increases, and it is often difficult to secure clearance between these and the wheel 6 side. Furthermore, even when it is desired to increase the effective diameter of the diaphragm and set the spring constant to a low value, a large air chamber 1 must be secured, and an increase in the size of the upper tank 2 tends to cause problems in the mountability of the device to the vehicle. becomes.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an air suspension that can cancel the bending moment acting on the strut when mounted on a vehicle, and that requires a relatively small installation space.

(Means for Solving the Problems) The air suspension according to the present invention particularly includes a rolling diaphragm in which a large-diameter attachment portion is attached to the outer shell and a small-diameter attachment portion is attached to the rolling guide. It is characterized in that the center line of the larger diameter mounting portion is offset to the outside of the vehicle with respect to the center line of the smaller diameter mounting portion.

(Function) The force acting in the direction along the center line of the large-diameter attachment part of the rolling diaphragm causes a bending moment to move toward the strut, which acts to cancel out the bending moment that acts on the strut when installed in a vehicle. .

(Example) FIG. 1 shows the main parts of an air suspension according to the present invention, and FIG. 2 is an overall configuration diagram of the air suspension. This air suspension is for attaching a front wheel 10 of a vehicle (not shown) to a vehicle body base 11, and a strut body 12, a rod portion 13 that retractably projects from the strut body 12, and the upper end of the rod portion 13 are integrally connected. An outer shell 14 , a substantially cup-shaped rolling guide 16 that is disposed opposite to the lower side of the outer shell 14 via an air chamber 15 and integrally connected to the upper end of the strut body 12 , and a downward cylindrical portion 141 of the outer shell 14
A rolling diaphragm (hereinafter simply referred to as a diaphragm) 17 having a large-diameter mounting portion 171 and a small-diameter mounting portion 172 in close contact with the upward cylinder portion 161 of the rolling guide 16 is integrally connected to the lower end of the strut body 12. a housing 18 to which the wheel 10 is pivotally mounted;
and a lower arm 20 connected to the vehicle body base 11 via a ball joint 19.

Here, the upper end of the rod portion 13 and the center wall 142 of the outer shell 14 are attached to the vehicle body base 11 via a strut mount 21. The strut body is of a twin tube type consisting of an outer cylinder and a pressure tube, and a piston 22 is slidably in contact with the inner wall, and furthermore,
A front guide 23 is attached to the upper end, and the rod portion 13 is in sliding contact therewith while maintaining airtightness.

The outer shell 14 has an inverted container shape, and a downward cylindrical portion 141 extending from a central wall 142 has a larger diameter on the upper side and a smaller diameter on the lower side, and both portions are formed continuously through a stepped portion 143. has been done. In particular, the lower center line of the downward cylindrical portion 141, that is, the center line Y-Y of the larger diameter side mounting portion 171, is the center line of the smaller diameter side mounting portion 172, which is the upper center line Y''-Y'
That's eccentric. Here, the rolling guide 16 with the small-diameter side attachment portion 172 is concentrically integrally connected to the strut body 12, and the rod portion 13 concentric with the strut body 12 side has its upper end attached to the center wall of the outer shell 14.
It is connected to the center position of 42. That is, here, the center line Y--Y of the small-diameter side mounting portion 172 is attached concentrically to the center wall 142 side of the outer shell 14, but the center line Y--Y= of the small-diameter side attachment portion 172 is attached concentrically to the center wall 142 side of the outer shell 14, but the center line Y-Y= of the small-diameter side attachment portion 172 is attached concentrically to the center wall 142 side of the outer shell 14. The portion 171 is eccentric with respect to the center line Y-Y. That is, the center line Y--Y of the larger-diameter mounting portion is eccentric to the outside of the vehicle by an offset amount J21 with respect to the center 112Y--Y' of the smaller-diameter mounting portion 172.

Further, the annular portion 173 extending downward from the small-diameter side mounting portion 172 of the diaphragm 17 contacts the outer wall of the rolling guide 16, but the position in the vertical direction up to its lowest end is such that the inner side of the vehicle is closer to the outer side of the vehicle. Greater than only 12. Therefore, at the position of the piston 22, the lateral force f due to the difference in contact length 2 degrees Celsius generates a moment m.

In the above description, reference numeral 24 denotes a crimping ring which moves to firmly fix the mounting portion of each diaphragm to the downward cylindrical portion 141 and the upward cylindrical portion 171. Further, reference numeral 25 indicates an O-ring, which ensures airtightness of the air chamber 15.

When this type of air suspension is installed on a vehicle,
The strut will receive a bending moment M1 due to the wheel reaction force. On the other hand, the pressurized gas in the air chamber 15 acts on the center line Y-
A pressurizing force F is generated along Y, which applies a bending moment M2 (=F-f1) to the strut side, and also generates a moment due to the difference in contact length of the diaphragms. As a result, bending moments M2 and m act in a direction that cancels out the bending moment M1 caused by the wheel reaction force, and the lateral bending moment M1 is applied to the sliding parts in the strut, that is, the piston 22 and the rod guide 23. Forces a and b can be reduced, the sliding resistance of the cylindrical portion can be lowered, smooth sliding movement can be obtained, and durability can be improved. In particular, the rolling guide 16 and the strut main body 12 are concentrically connected, making it easy to reduce the diameter of both, and accordingly, making it easy to reduce the diameter of the outer shell 14 side as well. Easy to improve.

Although the strut body 12 and rolling guide 16 of the air suspension shown in FIG. 1 are concentrically connected, they may alternatively be configured as shown in FIG. 3. In this case, the rolling guide 16 integral with the strut body 12a is eccentrically coupled by an offset amount p3. Further, the center line Y'-Y- of the small-diameter mounting portion, which is the centerline of the rolling guide 16, and the center line Y-Y of the large-diameter mounting portion are eccentrically opposed to each other by an offset amount ρ1. For this reason, here, the center line Y-Y of the larger diameter side attachment part as the air reaction force center axis is arranged outside the vehicle by J3 + 421 with respect to the center line of the strut side, and the lever specific gravity Bending moment M2a [=F
・(Jl + J3) ] can be easily strengthened, and there is an advantage that the effect of canceling out the bending moment M1 accompanying the wheel reaction force is greater.

(Effects of the Invention) As described above, in the air suspension according to the present invention, the large-diameter mounting portion, which is the center axis of the air reaction force, is placed on the rolling guide integrated with the strut body with respect to the center line of the small-diameter mounting portion. Since the center line is eccentric to the outside of the vehicle, the bending moment caused by the air reaction force can cancel out and reduce the bending moment caused by the wheel reaction force, improving the durability of the air suspension. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts of an air suspension as an embodiment of the present invention, FIG. 2 is a schematic diagram of the overall configuration of the same air suspension, and FIG. 3 is a main part of an air suspension as another embodiment of the present invention. A partial sectional view, FIG. 4 is a schematic diagram of a conventional air suspension. DESCRIPTION OF SYMBOLS 11... Vehicle body base, 12 - Strut main body, 13 - Rod part, 14... Outer shell, 15... Air chamber, 16... Rolling guide, 17... Diaphragm, 171... Large diameter Side mounting part, 172... Small diameter mounting part, Y-Y... Center line of large diameter side mounting part, Y'Y
'...Center line of the small diameter side mounting part. Diagram: District Diagram

Claims (1)

[Claims] an outer shell attached to the base of the vehicle body; a strut damper having a piston rod connected to the outer shell; a rolling guide disposed opposite to the outer shell via an air chamber and fixed to the strut damper; An air suspension comprising a rolling diaphragm having a large-diameter mounting section attached to the shell and a small-diameter mounting section attached to the rolling guide, the air suspension having a diameter relative to the center line of the small-diameter mounting section of the rolling diaphragm. An air suspension characterized by having the center line of the large side mounting part eccentric to the outside of the vehicle.