JP2018071596A - Coil spring used for vehicle suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of a lateral force in a coil spring that requires versatility. A coil spring is used for a suspension of a vehicle. This coil spring has a closed end structure in which each end is formed flat. Each section corresponding to at least one pitch from each terminal is a gradually changing section in which the coil diameter increases toward the center of the coil spring. The increasing width of the coil diameter per pitch in the gradually changing section is smaller than the wire diameter of the coil spring. [Selection] Figure 1

Description

  The present specification relates to a coil spring used for a suspension of a vehicle.

  Coil springs used for vehicle suspensions are generally roughly classified into a rough winding type mainly designed for mounting on a new vehicle and a direct winding type mainly designed for an aftermarket. Since the vehicle type to be used is specifically specified, the shape of the coiled coil spring can be designed in various ways according to the structure of the vehicle type. On the other hand, it is preferable that the direct-winding type coil spring has a simple shape because versatility that can correspond to various vehicle types is required. Therefore, the conventional direct-winding type coil spring has a cylindrical shape with both ends formed flat, and systematized by three elements (ie, product lineup) Has been. For example, Patent Document 1 discloses an example of a series winding spring.

Japanese Patent Laying-Open No. 2015-148267

  In the direct-winding type coil spring, the specifications are mainly determined by the above-described three elements, and the spring reaction force line is not particularly considered. The spring reaction force line indicates the direction of the reaction force generated by the spring. In an ideal coil spring, the spring reaction force line coincides with the spring axis, but in an actual coil spring, the spring reaction force line does not necessarily coincide with the spring axis. When the spring reaction force line is inclined with respect to the spring axis, a lateral force is applied from the coil spring to the shock absorber. The lateral force here means a force in a direction perpendicular to the direction of expansion and contraction of the shock absorber. Such a lateral force hinders the movement of the shock absorber, and can be a factor that deteriorates the steering stability and riding comfort of the vehicle.

  Therefore, this specification provides the technique which can suppress generation | occurrence | production of a lateral force in the coil spring in which versatility is required.

  This specification discloses the coil spring used for the suspension of a vehicle. In this coil spring, each end is formed flat. Each section corresponding to at least one pitch from each terminal is a gradually changing section in which the coil diameter increases toward the center of the coil spring. The increasing width of the coil diameter per pitch in the gradually changing section is smaller than the wire diameter of the coil spring.

  In the coil spring described above, the coil diameter is small at each end and the coil diameter is large at the center. According to such a shape, the inclination of the spring reaction force line with respect to the spring axis is suppressed, and generation of lateral force can be suppressed. In addition, the change of the coil diameter is made comparatively small, and specifically, the increase width of the coil diameter per pitch is smaller than the strand diameter of the coil spring. Thereby, the shape of the coil spring still maintains a shape close to a cylindrical shape, and the versatility is not greatly impaired.

The front view which shows the coil spring 10 of an Example. The top view of the coil spring 10 of an Example. The specifications of the sample 1 of the coil spring 10 and the conventional product 1 are shown in a table format. The specifications of the sample 2 of the coil spring 10 and the conventional product 2 are shown in a table format. The experimental results of measuring the lateral force of sample 1 and conventional product 1 are shown in tabular form. The experimental results of measuring the lateral force of sample 2 and conventional product 2 are shown in tabular form. The front view which shows the coil spring 110 of other embodiment. The front view which shows the coil spring 120 of another embodiment.

  In one embodiment of the present technology, the increase width of the coil diameter in the entire gradually changing section may be smaller than the wire diameter of the coil spring. According to such a configuration, since the change in the coil diameter is further suppressed, excellent versatility can be maintained.

  In one embodiment of the present technology, each section from each terminal to the center may be a gradually changing section. That is, the entire coil spring may be a gradually changing section. According to such a structure, generation | occurrence | production of a lateral force can be suppressed more effectively.

  In one embodiment of the present technology, in the gradual change section, the pitch may change according to the change in the coil diameter. Simply changing the coil diameter will change the pitch angle. In order to avoid the change in the pitch angle, the pitch may be further changed in accordance with the change in the coil diameter in the gradual change section.

  In one embodiment of the present technology, the spring axis of the coil spring may be curved or bent. According to such a configuration, when there is a lateral force that cannot be eliminated simply by changing the coil diameter, the lateral force can be eliminated or reduced by appropriately curving or bending the spring axis. it can. Here, the spring axis of the coil spring is a straight line connecting the centers of the coil shapes of the coil springs, and a straight line connecting the centers of curvature of the strands.

  In the above-described embodiment, it is preferable that the maximum displacement amount by which the spring axis is displaced with respect to the straight line connecting the center points of the respective ends of the coil spring is not more than half of the increase width of the coil diameter in the entire gradually changing section. According to such a configuration, even when the center line of the coil spring is curved or bent, the inner surface of the element wire does not protrude into the internal space of the coil spring, and the space for accommodating the shock absorber can be maintained.

  A coil spring 10 according to an embodiment will be described with reference to the drawings. The coil spring 10 is used for an automobile suspension and is combined with a shock absorber (not shown). Note that the configuration of the coil spring 10 described in the present embodiment can also be applied to a suspension of another vehicle such as a two-wheeled vehicle. The coil spring 10 is designed for the aftermarket and is mainly used in combination with a shock absorber having a vehicle harmonic function. This type of coil spring 10 is referred to as a direct winding type. The coil spring 10 for the aftermarket is required to be versatile enough to support various vehicle types. However, the coil spring 10 can also be employed in a suspension for mounting a new vehicle.

  As shown in FIGS. 1 and 2, the coil spring 10 is formed by forming a wire 12 in a coil shape, and generally has a cylindrical shape. The spring axis X of the coil spring 10 extends linearly. The spring axis X is a line connecting the centers of the coil shapes. The free length L of the coil spring 10 is not particularly limited, but can be set to 150 mm to 300 mm. Moreover, although the strand diameter E which is the diameter of the strand 12 is not specifically limited, It can be 8 mm-18 mm. Although it does not specifically limit for the material of the strand 12, For example, the metal material suitable for a coil spring, such as spring steel materials (SUP12 etc.), is employable. Although the total number of turns of the coil spring 10 is not particularly limited, for example, it is an integer winding, and can be 5 to 10 windings. The spring constant of the coil spring 10 is not particularly limited, but is 20 to 200 N / mm. Moreover, although the tensile strength of the coil spring 10 is not specifically limited, it is good in it being 1800-2000 MPa.

  Each terminal 10a, 10b of the coil spring 10 is a closed end, and each end 12a, 12b of the strand 12 is in contact with the adjacent strand 12, respectively. Each end 12a, 12b of the strand 12 may be slightly separated (for example, within a distance of 1.5 mm) from the adjacent strand 12. Each terminal 10a, 10b of the coil spring 10 is formed flat, for example, by grinding. The thickness t of each end 12a, 12b of the strand 12 is not particularly limited, but can be E / 3 to E / 2. In addition, the angle range θ (see FIG. 2) for grinding each of the terminals 10a and 10b is not particularly limited, but may be, for example, 270 degrees or more.

  In the coil spring 10 of the present embodiment, the coil diameter (coil outer diameter in FIG. 1) changes in the sections S1 and S2 from the terminals 10a and 10b to the central portion 10c. Hereinafter, the sections S1 and S2 in which the coil diameter changes are referred to as gradually changing sections. In one gradual change section S1, the coil diameter gradually increases from one terminal 10a toward the central portion 10c. That is, the coil diameter Dc at the central portion 10c is larger than the coil diameter Da at one terminal 10a. Similarly, in the other gradual change section S2, the coil diameter gradually increases from the other terminal 10b toward the central portion 10c. That is, the coil diameter Dc in the central portion 10c is larger than the coil diameter Db in the other terminal 10b. Although not particularly limited, in this embodiment, the coil diameters Da and Db at both terminals 10a and 10b are equal to each other, and have a symmetrical shape with the central portion 10c as a boundary.

  The change in the coil diameter described above is sufficiently small as compared with, for example, a conventional pigtail end type coil spring. Specifically, in each of the gradual change sections S <b> 1 and S <b> 2, the overall coil diameter increase width ΔD (that is, Dc−Da, Db−Da) is smaller than the strand diameter E of the strand 12. . Thereby, the shape of the coil spring 10 is still maintained in a shape close to a cylindrical shape, and the versatility required for products for the aftermarket is not greatly impaired. In another embodiment, the coil diameter increase width ΔD may be greater than or equal to the wire diameter E. However, even in this case, the increase width ΔD ′ of the coil diameter per pitch is preferably smaller than the wire diameter E. Note that the increase width ΔD ′ of the coil diameter per pitch is expressed by an expression of ΔD ′ = ΔD / N1 when the number of turns in the gradual change section S1 is N1, for example.

  In the coil spring 10 of the present embodiment, the coil diameters Da and Db are small at the terminals 10a and 10b, and the coil diameter Dc is large at the central portion 10c. According to such a shape, the inclination of the spring reaction force line with respect to the spring axis X is suppressed, and generation of lateral force can be suppressed. Hereinafter, the experimental results showing this will be described. In this experiment, two samples 1 and 2 of the coil spring 10 and conventional products 1 and 2 to be compared with each sample were prepared, and the lateral force generated when each was compressed was measured.

  FIG. 3 shows the specifications of the sample 1 and the conventional product 1 as a comparison target. As shown in FIG. 3, in the sample 1, the wire diameter E is 10.2 mm, the coil diameters Da and Db at the terminals 10a and 10b are 65.0 mm, and the coil diameter Dc at the center portion 10c is 69.mm. 9 mm, the free length L is 185.0 mm, and the spring constant is 49.5 N / m. On the other hand, in the conventional product 1, the coil diameters Da, Db, and Dc are constant at 65.0 mm, and the other points are the same as those of the sample 1. Note that the coil diameters Da, Db, and Dc here mean coil inner diameters.

  FIG. 4 shows the specifications of the sample 2 and the conventional product 2 as a comparison target. As shown in FIG. 4, in the sample 2, the wire diameter E is 11.3 mm, the coil diameters Da and Db (inner diameter here) at the respective terminals 10a and 10b are 65.0 mm, and the coil at the central portion 10c. The diameter Dc is 69.9 mm, the free length L is 175.0 mm, and the spring constant is 65.0 N / m. On the other hand, in the conventional product 1, the coil diameters Da, Db, and Dc are constant at 65.0 mm, and the other points are the same as those of the sample 2. The coil diameters Da, Db, Dc here also mean the coil inner diameter.

  FIG. 5 shows the experimental results of Sample 1 and Conventional Product 1. As shown in FIG. 5, in the coil spring 10 of the sample 1, when compressed until the height (length) reaches 150.0 mm, the load at that time is 1743.0 N, and a lateral force of 1.3 N is generated. did. Similarly, when compressed to a height of 132.5 mm, the load is 2614.7 N, a lateral force of 9.8 N is generated, and when compressed to a height of 77.0, Became 5331.4N and a lateral force of 53.3N was generated. On the other hand, in the conventional product 1, when the height was compressed to 150.0 mm, the load at that time was 1912.4 N, and a lateral force of 8.5 N was generated. Similarly, when compressed to a height of 132.3 mm, the load is 2881.0 N, a lateral force of 47.9 N is generated, and when compressed to a height of 79.5, Was 5911.7N and a lateral force of 262.7N was generated. As is apparent from the experimental results, the generation of lateral force is significantly suppressed in the coil spring 10 of the sample 1 as compared with the conventional product 1 having a constant coil diameter.

  FIG. 6 shows the experimental results of Sample 2 and Conventional Product 2. As shown in FIG. 6, when the coil spring 10 of sample 2 is compressed until the height (length) becomes 150.0 mm, the load at that time becomes 1870.9 N, and a lateral force of 10.4 N is generated. did. Similarly, when compressed to a height of 129.0 mm, the load is 3388.9N, a lateral force of 4.6N is generated, and when compressed to a height of 81.0, Became 6810.1N and a lateral force of 36.5N was generated. On the other hand, in the conventional product 2, when compressed to a height of 150.0 mm, the load at that time was 1898.6 N, and a lateral force of 39.2 N was generated. Similarly, when compressed to a height of 129.0 mm, the load is 3490.0 N, a lateral force of 91.5 N is generated, and when compressed to a height of 83.0, the load is Was 7045.0N, and a lateral force of 321.7N was generated. As is apparent from the experimental results, generation of lateral force is significantly suppressed even in the coil spring 10 of the sample 2 as compared with the conventional product 2 having a constant coil diameter.

  The shape of the coil spring 10 shown in FIG. 1 is an example, and can be variously changed. FIG. 7 shows a coil spring 110 according to another embodiment. In FIG. 7, the same or corresponding elements as those of the coil spring 10 of FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here. As shown in FIG. 7, in the coil spring 110, in addition to the two gradually changing sections S1 and S2, a constant section S3 having a constant coil diameter is further provided. The constant section S3 can be provided between the two gradually changing sections S1 and S2. In this case, each of the gradual change sections S1 and S2 may have a length of at least one pitch from each of the terminals 10a and 10b, and may further have a length of at least one pitch excluding the end winding portion. Good. In the coil spring 110 shown in FIG. 7 as well, in each of the gradual change sections S1 and S2, the increase width ΔD ′ of the coil diameter per pitch may be smaller than the strand diameter E, and more preferably The increase width ΔD of the coil diameter due to the entire variable sections S1 and S2 is preferably smaller than the wire diameter E. In the coil spring 110, the two gradually changing sections S1 and S2 have the same length, but the two gradually changing sections S1 and S2 may have different lengths.

  FIG. 8 shows another embodiment of a coil spring 120. In FIG. 8, the same or corresponding elements as those of the coil spring 10 of FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here. As shown in FIG. 8, in the coil spring 120, the spring axis X is bent. Thus, the spring axis X of the coil spring 120 may be bent or curved. This also applies to the coil springs 10 and 110 shown in FIGS. According to such a configuration, when there is a lateral force that cannot be eliminated simply by changing the coil diameter, the lateral force can be eliminated or reduced by appropriately curving or bending the spring axis X. Can do. Here, when the spring axis X is bent or bent, the spring axis X is displaced from a straight line Y connecting the center points Ca and Cb at the terminals 10a and 10b. The maximum displacement F of the spring axis X with respect to the straight line Y is not particularly limited, but may be less than or equal to half of the increase width ΔD of the coil diameter in the entire gradual change sections S1 and S2. According to such a configuration, even when the spring axis X of the coil spring 120 is curved or bent, the inner surface of the element wire 12 does not protrude into the internal space of the coil spring 120, and the space for accommodating the shock absorber can be maintained. it can.

  Specific examples have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in this specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10, 110, 120: Coil spring 10a: Coil spring terminal 10c: Coil spring center 12: Coil spring strands Da, Db, Dc: Coil diameter E: Wire diameter S1, S2: Gradual change section S3: Fixed section X: Spring axis ΔD: Coil diameter increase width ΔD ′: Coil diameter increase width per pitch

Claims (6)

A coil spring used for a vehicle suspension,
Each terminal is flat,
Each section for at least one pitch from each terminal is a gradually changing section in which the coil diameter increases toward the center of the coil spring,
The increase width of the coil diameter per pitch in the gradual change section is smaller than the wire diameter of the coil spring,
Coil spring.   The coil spring according to claim 1, wherein an increase width of the coil diameter in the entire gradually changing section is smaller than the wire diameter of the coil spring.   The coil spring according to claim 1 or 2, wherein each section from each terminal to the central portion is the gradual change section.   The coil spring according to any one of claims 1 to 3, wherein a pitch changes in accordance with a change in the coil diameter in the gradual change section.   The coil spring according to any one of claims 1 to 4, wherein a spring axis of the coil spring is curved or bent.   The maximum displacement amount by which the spring axis is displaced with respect to a straight line connecting the center points of the respective ends of the coil spring is not more than half of an increase width of the coil diameter in the entire gradually changing section. The coil spring described in 1.

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