JP2003049888A - Air spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air spring improving ride comfort by reducing hysteresis loss in a portion bending during expansion and compression displacements of an air spring diaphragm body. SOLUTION: The air spring 20 is provided with the air spring diaphragm body 21 having a first reinforcing cord 23 and a second reinforcing cord 24 laid in a direction crossing the first reinforcing cord 23 in an interior. Only the first reinforcing cord 23 is embedded in the portion B bending during expansion and compression displacements of the air spring film body 21, resistance (the hysteresis loss) due to friction with the air spring diaphragm body 21 and friction between the reinforcing cords during expansion and compression of the air spring diaphragm body 21 is reduced, and a spring constant of the air spring 20 is reduced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air spring, and more particularly to an air spring having excellent spring characteristics.

[0002]

2. Description of the Related Art In recent years, an air spring 5 has been used for a large vehicle such as a truck or a bus, for example, a suspension 4 connecting an axle 2 of a truck 1 and a vehicle body 3 as shown in FIG. The air spring 5 has a state shown in FIG. 8 (a) in which compressed air in and out flows in and out when the vehicle body leans due to a load or an increase / decrease of an occupant or a curve, and when the ground clearance of the vehicle changes at start and stop. From the same figure (b),
As shown in (c), it expands and contracts. The air spring 5 is relatively easy to obtain a soft spring property and can keep the vehicle height constant against changes in load.
Further, since the strength of the spring changes in proportion to the load, there is an advantage that the riding comfort does not change so much.

FIG. 8 shows a diaphragm type air spring. The air spring 5 is formed by an air spring film body (rubber film) constituting a main body by a diaphragm 6 having a cylindrical shape, and its upper end has an arc shape. The diameter is slightly reduced and airtightly fixed to the disc-shaped plate 7, and the lower end is folded back inwardly and is airtightly fixed to the upper end of the piston 8. A bump stopper 9 is provided on the upper end of the piston 8 so as to face the plate 7. Air spring 5
Holds a load equal to the product of the internal pressure of the piston 8 and the effective area of the diaphragm 6, and when the piston 8 expands and contracts due to the vertical movement of the axle 2, the piston 8 acts as a spring by the compressive elasticity of air. The shape is such that the diameter gradually expands to the lower end, and the effective area of the diaphragm 6 changes in response to the load change.

Inside the diaphragm 6 of the air spring 5, as shown in FIG. 9, a reinforcing cord (corresponding to a tire cord in a tire) 10 is embedded in a mesh shape from the upper end to the lower end to have a predetermined strength. . Reinforcing cord 10
Is the axis of expansion and contraction of the diaphragm 6 (hereinafter referred to as "expansion and contraction axis").
The first reinforcing cord 11 laid at an angle (for example, about 65 °) to the right direction in the figure,
The first reinforcing cord 11 is composed of a second reinforcing cord 12 which is laid symmetrically with respect to the expansion / contraction axis line in the lower right direction in the figure, and is a so-called bias structure cord.

[0005]

However, in the conventional air spring 5, the reinforcing cord 10 of the diaphragm 6 is used.
Is the bias structure code (hereinafter “bias structure code 1
Since the diaphragm 6 is embedded from the upper end to the lower end of the diaphragm 6, the bias structure cord 10 is deformed by the movement of the piston 8 and becomes a resistance due to friction with the rubber film. That is, as shown in FIG. 10A, at the time of rebound when the diaphragm 6 is expanded (the piston 8 is pushed out of the diaphragm 6), the bias structure cord 10 has an upper part A that does not bend when the diaphragm 6 expands and contracts and a lower part B that bends. 11 (a) and (b)
As shown in Fig. 10, the first and second reinforcing cords 11 and 12 have the same inclination angle (about 65 °), and there is no change in angle, but the diaphragm 6 is shortened as shown in Fig. 10B ( At the time of bouncing (the piston 8 has entered into the diaphragm 6), the bent lower portion B of the diaphragm 6 is pulled inward by the piston 8 and pulled in the direction of the expansion / contraction axis. 10 is pulled in the direction of the expansion / contraction axis, and FIG.
As shown in (c), the inclination angles of the first and second reinforcing cords 11 and 12 with respect to the expansion / contraction axis direction become small (for example, about 45 °).

As described above, when the diaphragm 6 expands and contracts (the piston 8 is displaced by the stroke S), the first and second bias structure cords 10 in the bending portion B are bent.
Of the reinforcing cords 11 and 12 in the direction of the expansion / contraction axis (65 ° to 45 °), which causes friction with the rubber film, and friction (interference) between the reinforcing cords (reinforcing cords 11 and 12). Due to this, hysteresis loss occurs and it becomes resistance. As a result, the spring strength of the air spring 5 does not change in proportion to the load, and there is a problem that the riding comfort is poor.

Therefore, it is an object of the present invention to provide an air spring which reduces the hysteresis loss at the portion of the air spring film that bends when it expands and contracts to improve the riding comfort.

[0008]

In order to achieve the above object, in the invention of claim 1, the first reinforcing cord and the first reinforcing cord are provided.
A second reinforcing cord laid in a direction intersecting with the reinforcing cord inside the air spring, the air spring having an air spring film body therein, wherein the first reinforcing cord is provided at a portion that bends when the air spring film body expands and contracts. By embedding only, the resistance (hysteresis loss) due to the friction with the air spring film body and the friction between the reinforcing cords during expansion and contraction is significantly reduced.

According to the second aspect of the invention, the reinforcing cord is the first cord.
Bias cord is laid at an angle with respect to the expansion / contraction axis direction of the air spring film body, and the second reinforcement cord is laid substantially symmetrically with respect to the first reinforcement cord with the expansion / contraction axis as the axis of symmetry. The conventional bias structure code arrangement is used as the structure code arrangement. In the invention of claim 3, the first reinforcing cord is laid substantially parallel to the expansion / contraction axis of the air spring film body, and the second reinforcing cord is substantially orthogonal to the first reinforcing cord. As the radial structure cords to be laid, only the first reinforcing cords that are substantially parallel to the bending portion of the air spring membrane in the direction of the expansion / contraction axis are used, and the resistance (hysteresis loss) due to friction during expansion and contraction and friction between the reinforcing cords is reduced. Further reduce.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. FIG. 1 shows a first embodiment of an air spring according to the present invention, and is a partially cutaway perspective view in a state where an air spring film body is seen through. FIG. 2 is an operation explanatory view of the air spring shown in FIG.
[Fig. 3] is an explanatory diagram showing displacement of a reinforcing cord of the air spring shown in Fig. 2.

As shown in FIG. 1, the air spring 20 is
In the diaphragm type air spring, the reinforcing cord 22 is embedded in the air spring film body 21 to form the diaphragm 25. The diaphragm 25 has a cylindrical shape, an upper end thereof has an arc shape, is slightly reduced in diameter, and is airtightly fixed to a disc-shaped plate 26, and a lower end thereof is substantially inwardly U-shaped.
It is folded back in a letter shape and is airtightly fixed to the upper end of the piston 27. A bump stopper 28 is provided on the upper end of the piston 27 so as to face the plate 26. The plate 26 is provided with a supply / discharge nozzle (not shown) for supplying compressed air to the diaphragm 25. Piston 27
The outer peripheral surface 27a has a shape in which the diameter is smoothly expanded from the substantially center to the lower end (base end).

The air spring film body 21 is shown in FIG.
As shown in (a) and (b), the part from the upper end to the position near the center (hereinafter referred to as “upper A”) does not bend during expansion and contraction, and the part from the position near the center to the position near the lower end ( Hereinafter, the “lower portion B” is drawn inward and bent while abutting on the outer peripheral surface 27a of the piston 27 from the upper end to the vicinity of the lower end according to expansion and contraction.

The reinforcing cord 22 is a first reinforcing cord 23.
And the second reinforcement cord 24, the first reinforcement cord 2
3 is laid from the upper end to the lower end of the air spring film body 21 at an angle (for example, about 65 °) with respect to the expansion / contraction axis direction of the air spring film body 21 so as to incline to the right in the figure. There is. Also, the second reinforcing cord 24 is
The first reinforcing cord 23 is laid substantially symmetrically with respect to the expansion / contraction axis with respect to the expansion / contraction axis, and is inclined downward to the right in the drawing.
In addition, it is laid from the upper end to a position near the center, and is not laid from the position near the center to the lower end, that is, at a portion of the lower portion B where the air spring film body 21 bends. That is, the reinforcing cord 22 has a bias structure cord arrangement in which the portion (upper portion A) that does not bend during expansion and contraction includes the first reinforcing cord 23 and the second reinforcing cord 24, and the portion that bends during expansion and contraction (lower portion B) expands and contracts. Only the first reinforcing cord 23 is arranged so as to be inclined with respect to the axis.

The operation will be described below. As shown in FIG. 2A, the first reinforcing cord 23 and the second reinforcing cord 24 in the upper part A at the time of the rebound in which the air spring 20 is stretched have the inclination angle ( About 65 °), and the first reinforcing cord 23 in the lower portion B also forms the inclination angle (about 65 °) as shown in FIG. 3B. When the air spring 20 bounces from the extended rebound state by the stroke S as shown in FIG. 2B, the first reinforcing cord 23 of the lower portion B is pulled inward along the outer peripheral surface 27a of the piston 27. Accordingly, it is pulled in the expansion / contraction axis direction, and the inclination angle of the first reinforcing cord 23 with respect to the expansion / contraction axis direction becomes small as shown in FIG.
°). The upper part A of the reinforcement cord 22 at the time of bounding
The inclination angles of the first and second reinforcing cords 23 and 24 in the above do not change.

The air spring film body 21 has only the first reinforcement cord 23 embedded in the bending lower portion, so that the air spring film body 21 is expanded and contracted at the time of expansion and contraction.
The friction (hysteresis loss) due to the friction with the rubber forming the rubber and the friction between the reinforcing cords is significantly reduced. As a result, the spring constant of the air spring 20 is reduced and the riding comfort is improved.

FIG. 4 shows a second air spring according to the present invention.
FIG. 5 shows the embodiment and is a partially cutaway perspective view with the air spring film body seen through; FIG. 5 is an operation explanatory view of the air spring shown in FIG. 4; and FIG. 6 is a change in the reinforcement cord of the air spring shown in FIG. FIG. Incidentally, in FIG. 4, the members corresponding to those in FIG.

The air spring 30, as shown in FIG.
A reinforcing cord 32 is embedded in the air spring film body 31 to form a diaphragm 35. Reinforcement cord 32
Is composed of a first reinforcing cord 33 and a second reinforcing cord 34, and the first reinforcing cord 33 is the air spring film body 3
1 is laid from the upper end to the lower end of the air spring film body 31 in the vertical direction in the figure substantially parallel to the expansion / contraction axis direction of the air spring film body 31. Further, the second reinforcing cord 34 is laid horizontally in the drawing so as to be substantially orthogonal (about 90 °) to the first reinforcing cord 33, and is laid from the vicinity of the upper end to the position near the center, It is not laid from the position near the center to the lower end, that is, in the portion of the lower portion B where the air spring film body 31 bends. That is, the reinforcing cord 32 has a radial structure cord arrangement including a first reinforcing cord 33 and a second reinforcing cord 34 in which a portion that does not bend when expanding and contracting (upper portion A) is orthogonal to each other, and a portion that bends when expanding and contracting (lower portion B). ) Is only the first reinforcing cord 33 arranged substantially parallel to the expansion / contraction axis.

As shown in FIG. 5A, the air spring 3
At the time of rebound in which 0 is extended, the first reinforcing cord 33 and the second reinforcing cord 34 in the upper portion A are
As shown in FIG. 6 (a), the radial structure cords are arranged, and the first reinforcing cord 33 in the lower portion B has an interval between adjacent reinforcing cords 33 as shown in FIG. 6 (b). It has the same spacing as the spacing in A.

When the air spring 30 is bound from the expanded rebound state by the stroke S as shown in FIG. 5 (b), the first reinforcing cord 33 of the lower portion B is used.
6 is drawn inward along the outer peripheral surface 37a of the piston 37, and is pulled in the direction of the expansion / contraction axis accordingly.
As shown in, the interval between the adjacent first reinforcing cords 33 is slightly narrowed. Reinforcement cord 32 when bound
The first and second reinforcing cords 33, 34 in the upper part A of the do not change.

The air spring film body 31 has only the first reinforcing cord 33 embedded in the lower portion as the bent portion, and further, the first reinforcing cord 33 is laid in parallel with the expansion / contraction axis. By virtue of the presence of the reinforcing cords, the friction with the rubber during expansion and contraction and the resistance (hysteresis loss) due to the friction between the reinforcing cords are further reduced as compared with the first embodiment in which the reinforcing cords are laid obliquely with respect to the expansion and contraction axis. It

[0021]

As described above, in the invention of claim 1, the reinforcing cord embedded in the bending portion of the air spring membrane is only the first reinforcing cord.
The resistance (hysteresis loss) due to the friction with the air spring film body and the friction between the reinforcing cords at the time of expansion and contraction is significantly reduced, and as a result, the spring constant of the air spring is reduced and the riding comfort is improved.

According to the second aspect of the invention, it is possible to use the cord arrangement of the bias structure cord in which the first reinforcing cord and the second reinforcing cord are arranged so as to intersect with each other, and the conventional manufacturing line is used as it is. It is possible to reduce the cost. According to the invention of claim 3, in the air spring film body, since the reinforcing cord embedded in the bending portion is only the first reinforcing cord laid substantially parallel to the expansion and contraction axis, the air spring film can be made to be elastic at the time of expansion and contraction. The resistance (hysteresis loss) due to the friction between and the reinforcing cords is further reduced.

[Brief description of drawings]

FIG. 1 shows a first embodiment of an air spring according to the present invention, and is a partially cutaway perspective view in a state in which an air spring film body is seen through.

FIG. 2 is an operation explanatory view of the air spring shown in FIG.

FIG. 3 is an explanatory diagram showing a displacement of a reinforcing cord of the air spring shown in FIG.

FIG. 4 is a partially cutaway perspective view showing an air spring according to a second embodiment of the present invention, as seen through an air spring film body.

5 is an explanatory view of the operation of the air spring shown in FIG.

6 is an explanatory diagram showing displacement of a reinforcing cord of the air spring shown in FIG.

FIG. 7 is a side view of a vehicle using an air spring.

FIG. 8 is an operation explanatory view of the air spring shown in FIG.

9 is a partially cutaway perspective view of an air spring film body of the conventional air spring shown in FIG. 8 seen through.

FIG. 10 is an operation explanatory view of the air spring shown in FIG.

11 is an explanatory diagram showing a displacement of a reinforcing cord of the air spring shown in FIG.

[Explanation of symbols]

20, 30 Air spring 21, 31 Air spring membrane 22, 32 reinforcement cord 23, 33 First reinforcement cord 24, 34 Second reinforcement cord 25, 35 diaphragm 26, 36 plates 27, 37 piston 28, 38 bump stopper

Claims (3)

[Claims] 1. An air spring comprising an air spring film body having therein a first reinforcing cord and a second reinforcing cord laid in a direction intersecting with the first reinforcing cord, the air spring. An air spring, wherein only the first reinforcing cord is embedded in a portion that bends when the film body expands and contracts. 2. The first reinforcement cord is laid at an angle with respect to the expansion / contraction axis direction of the air spring film body, and the second reinforcement cord is arranged with respect to the first reinforcement cord. The air spring according to claim 1, wherein the air spring is laid substantially symmetrically with the expansion / contraction axis as a symmetry axis. 3. The first reinforcing cord is laid substantially parallel to the expansion / contraction axis of the air spring film body, and the second reinforcing cord is laid so as to be substantially orthogonal to the first reinforcing cord. The air spring according to claim 1, wherein the air spring is provided.