JPH04973Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] This invention is a protective cover for a vehicle suspension that supports the vehicle body with springs and dampers, alleviates vibrations and shocks from the road surface, and improves steering stability and ride comfort. It is related to. [Prior Art] Conventionally, in this type of vehicle suspension, a protective cover having a bellows structure that protects the interior of the suspension from the intrusion of water, mud, etc. is described in Japanese Patent Application Laid-Open No. 123023/1983. [Problem to be solved by the invention] In general, vehicle suspensions have a very large difference between the contracted state and the relaxed state, that is, the compression stroke. A compressor with a compression stroke of On the other hand, in the case of a bellows structure, if the number of peaks and valleys in the bellows part is reduced, the thickness in the longitudinal direction during compression can be reduced and the compression stroke can be increased. The number of peaks and valleys was reduced to accommodate the suspension's large compression stroke. However, when the angle of the crests of such a protective cover is increased, the adjacent troughs move a long distance during contraction, and as the troughs move, the crests move outward; Since the diameter of the shock absorber is fixed, as the peak moves outward, it deforms into an elliptical shape in the circular cross-sectional direction, and as a result, the shock absorber gets pinched by the coil spring on the outside of the shock absorber and breaks. accidents had occurred. Also, if you increase the angle of these peaks,
During contraction, the amount of deformation of the crest increases, so the crest warps and bulges due to the strain caused by the deformation, and when it is suddenly released from the contracted state, the two forming the crest A problem has arisen in that the sides collide with each other, producing a collision sound, which reverberates within the protective cover, becomes vibration, and is transmitted as noise inside the car. This invention was developed in view of the conventional problems as described above.
The bellows structure has alternating large valleys and small valleys, and the angle of the peaks, the pitch between the large valleys, the depth of the large valleys, and the depth of the small valleys are each set to specific values. In relation to this, by configuring the structure in such a way that the small troughs move outward from the large troughs and are surrounded by the large troughs during contraction, the deformation strain during shrinkage is absorbed by the small troughs and the crests This prevents the edges of the crest from colliding with each other by preventing an elliptical circle from forming and preventing the two sides of the crest from colliding with each other in close contact with each other during contraction. A vehicle that can reliably prevent the noise caused by the expansion and contraction of the suspension, and also prevent damage that occurs due to the expansion of the crests, and further expand and contract smoothly as the suspension expands and contracts by increasing the contraction stroke. The purpose of this invention is to provide a protective cover for the suspension of the vehicle. [Means for Solving the Problems] The present invention is configured as follows as a technical means for achieving the above object. In other words, the structure is such that a protective cover for a vehicle suspension has a bellows structure in part.
It has alternating large valleys and small valleys, and the following formula: X(1-Y) {1/cos(A/2)-1} ≦0.13 0.9 A≦80° R≦C/5 Where, A is the angle of the peak, B is the pitch between one large valley and the next large valley, C is the depth of the large valley, and D is the depth of the small valley. R is the radius of curvature of the peak. This is a protective cover for a vehicle suspension, which satisfies the following conditions and is characterized in that the small trough moves outward from the large trough and is surrounded by the large trough when contracted. [Function] According to the protective cover for a vehicle suspension according to the present invention, the deformation strain at the time of contraction is absorbed by the small valleys of the bellows structure being surrounded by the large valleys, and the peaks have an elliptical shape. No deformation occurs. Therefore, during contraction, the surfaces of the two sides that make up the peak are in close contact with the whole and do not collide irregularly, and noise caused by the sides of the peak colliding with each other is not generated. . Since the crests do not undergo deformation during contraction, damage to the crests caused by expansion of the crests is prevented. In addition, when contracting, the small valleys are surrounded by large peaks, allowing the bellows structure to have a large contraction stroke.
This allows the suspension to contract smoothly as it expands and contracts. [Example] An example of the present invention will be described with reference to the drawings. The suspension 2 is located at a position that connects the vehicle body and the tires 1, and serves to alleviate vibrations and shocks from the road surface. This suspension 2 is
This spring and a shock absorber 5 as a damper are incorporated therein substantially concentrically, and the outside of the shock absorber 5 is covered with a protective cover 3. This protective cover 3
has attachment parts 12 at both upper and lower ends of the bellows part 11,
The mounting part 12 is in close contact with the shock absorber 5,
Its outer periphery is tightened with a metal fitting 13 to seal it. The peak portion 15 of the bellows portion 11 is configured to be several millimeters smaller than the inner diameter of the coil spring 4 so as not to be pinched by the coil spring 4 and damaged when the suspension 2 contracts. The bellows part 11 has a plurality of air holes in a part thereof. As shown in FIG. 4, the structure of the bellows portion 11 has large troughs 16a and small troughs 16b alternately, and the angle A of the crest 15 is such that the angle A of the ridge 15 is such that the large trough 16a and the next large trough 16a are different from each other. The bellows structure has a bellows structure that satisfies the following formula between the pitch B, the depth C of the large trough 16a, and the depth D of the small trough 16b.
However, here, angles are expressed in degrees. X(1-Y) {1/cos(A/2)-1} ≦0.13 X=C/B≦0.7 Y=D/C≦0.9 A≦80° In the above formula, X(1-Y){1 /cos(A/2)-1}
is a mathematical formula representing the degree to which the large valley portion 16a of the bellows portion 11 deforms inward during contraction. However, since the large valley part 16a has a constant circumference, the actual bellows part 11 does not deform inward, but appears as a distortion in the bellows part 11, and the bellows part 11 breaks its circular shape and becomes distorted. do. this is,
The same goes for the peaks, which also lose their circular shape and become distorted during contraction. At this time, this transformation is the above X(1-Y){1/cos(A/
2)-1} The deformation will be distorted depending on the degree of the numerical value of the equation, so if this value exceeds 0.13, an accident may develop in which the distorted part is bitten off by the coil spring, or rapid deformation may occur. It was found that this appears as the generation of sounds during contraction and relaxation. By keeping this value to 0.13, you can prevent the coil spring from being bitten by the coil spring, and prevent rapid contraction.
This makes it possible to prevent the sound from being generated during relaxation. Further, the ridge portion 15 of the bellows portion 11 has an extremely small radius of curvature R, and satisfies R≦C/5. The shape of the peak portion 15 is such that adjacent portions are substantially similar to each other with the small valley portion 16b at the center.
The heights C of the peaks 15 are approximately equal. Angle A of peak 15
can be divided into approximately equal parts along a plane from the top of the mountain portion 15 toward the center line of the protective cover 3. Here, from FIG. 5, the height of α with respect to the large valley portion 16a is expressed as (C+D), so if half the width dimension of the small valley portion 16b is P, then D:P=(C+D):B/ 2 In other words, P=BD/2(C+D). Therefore, the angle A of the peak portion 15 and the large valley portion 16a
The relationship between pitch and the next large valley 16a is tan(A/2)=(B/2-P)/C=B/2(C+D) That is, A=2tan ^-1 {B/2(C+D) )} Here, if C/B=X and D/C=Y, then C
=BX, D=CY=BXY, and the angle A of the crest 15 is as follows: A=2tan ^-1 {1/2X(1+Y)}... In this embodiment, the angle A of the peak portion 15 is 80°.
It is as follows. When the angle A of the peak 15 exceeds 80°,
The bellows portion 11 does not contract and expand well, and cannot respond to repeated instantaneous contractions and expansions. Next, inward deformation of the large valley portion 16a during contraction will be investigated. Here, assuming that the position of the small trough 16b is fixed during contraction, the displacement of the large trough 16a is calculated by drawing a circle downward from the large crest 15 to point β.
It is considered that the displacement of the large peak portion 15 in terms of operation moves to a point γ drawn in a circle upward from the small valley portion 16b as a starting point.
Therefore, now let the respective operational displacements be T ₁ and T ₂
Then, the substantial inward displacement Tr of the large valley portion 16a is expressed as Tr=T ₁ −T ₂ . Here, T ₁ =C/cos(A/2)-C T ₂ =D/cos(A/2)-D Therefore, Tr=T ₁ -T ₂ =(C-D) {1-cos( A/2)-1} By the way, as mentioned above, CD=BX-BXY=
Since BX(1-Y), Tr=BX(1-Y) {1/cos(A/2)-1} Then, the large valley 16a and the next large valley 1
When pitch B with 6a is 23mm, displacement Tr is 3mm
Since it is necessary that the following is true, the above formula becomes: X(1-Y){1/cos(A/2)-1}≦0.13... Here, this left side X(1-Y) {1/
cos(A/2)-1} is called the displacement value T. This displacement value T is the angle A of the peak, the pitch B between one large valley and the next large valley, and the depth C of the large valley. , and the depth D of the small valley. When the bellows portion 11 contracts, the two sides forming the peak portion 15 deform as the bellows portion 11 moves. When the displacement value Tr exceeds 0.13, the bellows part 1
The deformation of item 1 manifests itself as the generation of sounds when contracting or relaxing, or can lead to an accident in which the coil spring is bitten by the coil spring. If the displacement value Tr is 0.13 or less, the protective cover 3 does not generate sound when contracting or relaxing.
is obtained. As mentioned above, since the angle A of the crest 15 is 80 degrees or less in the expressions and expressions, when expressed in a graph, it becomes as shown in FIG. 6. In FIG. 6, line 1 represents the formula, and line 2 represents the formula. The angle of the peak 15 is
80° or less, so when the angle of the peak 15 in the equation is gradually reduced from 80°, line 1 moves to the right in the figure, so the range that can be taken in this invention is line 1, line 2, the range surrounded by lines 3 and 4. As mentioned above, the bellows structure according to the present invention has D/
Since B≦0.7, the height of the peak portion 15 is low, and therefore the volume of the peak portion 15 relative to the bellows portion 11 is smaller than that of the conventional protective cover, and the volume inside the protective cover 3 when contracted or expanded is small. changes can be kept small,
Even if the ventilation hole is small and does not reduce the strength of the bellows portion 11, it can easily follow the compression and expansion of the suspension 2. In addition, the bellows structure according to the present invention has a large valley portion 1.
6a and small valleys 16b alternately, and the ratio of the large valleys 16a to small valleys 16b is 0.9 or less, that is, D/C≦0.9, so that the small valleys 16b become the large valleys during contraction. 16a, the small valley 16b is surrounded by the large valley 16a, resulting in a large retraction stroke and a protective cover 3 suitable for compression of the suspension 2. Furthermore, since the protective cover 3 according to the present invention has the above-mentioned bellows structure, the mountain portion 15 that is generated when contracted is
By reducing the deformation of , the entire two sides constituting the peak portion 15 fit together exactly. Therefore, it is possible to prevent the generation of noise caused by the sides of the peak portion 15 expanding during contraction and irregularly colliding with each other, which conventionally occurs. Furthermore, since the deformation of the crest 15 is small even during contraction, even if the protective cover 3 is placed close to the coil spring 4, the crest 15 of the protective cover 3 will not be bitten off by the coil spring 4. Therefore, the suspension 2 can be made smaller. In particular, the bellows part 11 according to the present invention satisfies the following: This allows the above characteristics to be exhibited significantly. The protective cover 3 is made of thermoplastic plastic or rubber. Examples of thermoplastic plastics include polyolefin resins such as polypropylene and polyethylene, polyamide resins, ethylene-vinyl acetate copolymer resins, and polychloride resins. Vinyl resin and other thermoplastic elastomer resins such as polyester, urethane, styrene-butadiene, and olefin can be used. As the rubber, synthetic rubber or natural rubber can be used. Furthermore, it is also possible to form a multilayer structure in which a plurality of these thermoplastic plastics or rubbers are combined. Examples 1 to 3 and Comparative Examples Table 1 shows the amount of DOP (di-2-ethylhexyl phthalate) per 100 parts of polyvinyl chloride resin.
A protective cover is made by blow molding soft polyvinyl chloride containing 65 parts, and has a length of 250 mm, an outermost diameter of 100 mm, 9 peaks, and 8 air holes with a diameter of 8 mm.

[Table] The above protective covers are attached to each McPherson type suspension strut device, and the
After 48 hours of stretching and contraction, cracking and noise were observed. The results are shown in Table 2.

[Table] In Table 2, regarding crackability, those that did not develop cracks are indicated by ○, those that did develop cracks are indicated by ×,
Regarding noise, the number of people who felt noise among the 10 panelists was shown. From Table 2, it is clear that the protective cover according to the present invention has excellent performance. (Effect of the invention) The present invention provides a protective cover for a vehicle suspension having a bellows structure in part, which has alternating large valleys and small valleys, and has the following formula X(1-Y) {1 /cos(A/2)-1} ≦0.13 The pitch to the next large valley, C is the depth of the large valley, D is the depth of the small valley, and R is the radius of curvature of the peak. The structure satisfies the following conditions and is configured so that the small valley moves outward from the large valley and is surrounded by the large valley during contraction, so the small valley absorbs the deformation strain during contraction. Does not cause deformation of the mountain part,
During contraction, the surfaces of the two sides that make up the ridges come into close contact with the whole to prevent them from colliding irregularly, thereby reliably preventing the generation of noise caused by the sides of the ridges colliding with each other. can be done, and
Prevents damage caused by expansion of the mountain,
Furthermore, it is possible to obtain a protective cover that can take a large contraction stroke and can cope with the expansion and contraction of a vehicle suspension that requires high cycles of expansion and contraction.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the protective cover according to the present invention attached to a car, Fig. 2 is an enlarged sectional view of a part of Fig. 1, Fig. 3 is a front view of the protective cover, and Fig. 4. is a sectional view showing the shape of the bellows part, FIG. 5 is a diagram schematically showing the shape of the bellows part, and FIG. 6 is a diagram showing the relationship between X and Y. 2...Suspension, 3...Protective cover, 1
1... Bellows part, 15... Mountain part, 16a... Large valley part, 16b... Small valley part.

Claims (1)

[Claim for Utility Model Registration] A protective cover for a vehicle suspension having a bellows structure in part, which has alternating large troughs and small troughs, and which has the following formula X(1-Y) {1/ cos(A/2)-1} ≦0.13 C is the depth of the large valley, D is the depth of the small valley, and R is the radius of curvature of the peak. A protective cover for a vehicle suspension, which satisfies the following conditions and is characterized in that the small valley moves outward from the large valley and is surrounded by the large valley when contracted.