JP2019127945A - Coil spring and suspension device for vehicle - Google Patents

Abstract

To provide a coil spring for a suspension device in which a peak of stress is lowered, and a variation of the stress is small.SOLUTION: A coils spring 2 composed of a strand 4 which is formed into a spiral shape has: a lower-side winding part 20 supported to a lower-side spring seat 10; an upper-side winding part 21 supported to an upper-side spring seat 11; and an effective part 22. When the coil spring 2 is compressed between the lower-side spring seat 10 and the upper-side spring seat 11, stress is generated at the strand 4. In a state that the coil spring 2 is compressed, the effective part 22 has a first portion S1 including a peak part of the stress, and a second portion S2 at a side opposite to the peak part of the stress in a peripheral direction. The lower-side winding part 20 has a lower terminal 4a arranged below the second portion S2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coil spring and a vehicle suspension system using the coil spring.

  A coil spring is known as a suspension spring used for a suspension system of vehicles, such as a car. The coil spring for the suspension system expands and contracts between a maximally stretched state (rebound) and a maximally compressed state (full bump) to absorb the vibration transmitted from the road surface to the vehicle. For example, a knee action type suspension device described in Patent Document 1 includes: an arm member pivoting vertically about a pivot; and a coil spring (suspension spring) disposed between the arm member and a vehicle body Have. The strut type suspension device described in Patent Document 2 includes a coil spring (suspension spring) disposed between a lower side spring seat and an upper side spring seat, and a shock absorber.

  In the industry, it is strongly desired to reduce the weight of the suspension coil spring from the viewpoint of reducing the weight of the vehicle. It is known that the stress of each portion in the longitudinal direction of the wire is not constant when the coil spring is loaded. In order to reduce the weight of such a coil spring, it is effective to reduce the variation in stress as much as possible. For example, as described in Patent Document 3, alternately forming a large diameter wire portion and a small diameter wire portion in the lengthwise direction of the wire as one means for reducing variation in stress of a coil spring. Has been proposed. However, in order to manufacture a coil spring having a large diameter wire portion and a small diameter wire portion, special manufacturing equipment is required.

Unexamined-Japanese-Patent No. 2004-50906 Japanese Patent Laid-Open No. 2000-103216 JP 59-219534 A

  In the conventional suspension device, in a state where the coil spring is compressed, a peak portion where the stress is particularly large may exist in a part in the length direction of the strand. Such a peak portion of the stress hinders the stress equalization of the coil spring. Then, when the present inventors intensively studied to equalize the stress of the coil spring for the suspension system, optimizing the position of the tip (lower end) of the lower side wound portion of the coil spring is to equalize the stress. The knowledge that it is effective was obtained.

  An object of the present invention is to provide a coil spring capable of reducing a peak of stress generated in a strand and reducing variation in stress, and a suspension system for a vehicle.

  In one embodiment of the present invention, a lower side wound portion formed of a helically formed strand and supported by a lower spring seat, and an upper side wound winding supported by an upper spring seat. And a coil spring having an effective portion between the lower side coil and the upper coil, and the coil spring is compressed to generate stress in the wire. A first portion having a peak portion of the stress and a second portion opposite to the peak portion in the circumferential direction in a circumferential direction of the portion, and the lower side winding portion And a lower terminal disposed below the second portion.

  The effective portion may be substantially cylindrical and at an equal pitch, and may have a peak portion of the stress in a part of the effective portion in the circumferential direction. Alternatively, the pitch of the effective portion may be an unequal pitch that changes in the axial direction of the coil spring, and the stress peak portion may be included in a part of the effective portion in the circumferential direction. The wire diameter may be constant over the entire length of the effective portion.

  One embodiment of the suspension system for a vehicle is a knee action type having an arm member pivoting up and down about a pivot and a coil spring biasing the arm member, wherein the coil spring is It has a lower side wound portion supported by the lower side spring seat, an upper side wound portion supported by the upper side spring seat, and an effective portion. In a state where the coil spring is compressed and stress is generated in the strand, the first portion having the stress peak portion in the circumferential direction of the effective portion and the stress peak portion on the opposite side in the circumferential direction And the lower end wound portion includes a lower terminal disposed below the second portion on the side far from the pivot.

  Another embodiment of the vehicle suspension system is a strut type having a strut and a coil spring, wherein the coil spring is supported by a lower side wound portion supported by a lower side spring seat, and an upper side spring It has an upper side wound portion supported by a seat and an effective portion. In a state where the coil spring is compressed and stress is generated in the strand, the first portion having the stress peak portion in the circumferential direction of the effective portion and the stress peak portion on the opposite side in the circumferential direction And the lower end wound portion includes a lower terminal disposed below the second portion outside the vehicle.

  According to the coil spring of the present embodiment, by optimizing the position of the lower end of the wire, the peak (maximum value) of the stress generated in the effective portion can be reduced, and the stress distribution of the wire ( The difference between the maximum value and the minimum value) can be made smaller than that of the conventional coil spring.

The side view which shows the state by which the coiled spring of the knee action type suspension system which concerns on 1st Embodiment was compressed to the full bump position in a partial cross section. The side view which shows the state which the coil spring of the suspension system shown by FIG. 1 extended to the rebound position in a partial cross section. The graph showing the relationship between the number-of-turns position from the lower end of the coil spring, and height. The graph showing the relationship between the number of turns from the lower end of the coil spring and the radius in the coil. The top view which looked at the same coil spring from the perpendicular direction. The figure showing each stress distribution of the same coiled spring and the conventional coiled spring. The figure showing each stress distribution of the coil spring which concerns on 2nd Embodiment, and the conventional coil spring. The figure showing each stress distribution of the coil spring which concerns on 3rd Embodiment, and the conventional coil spring. The figure showing each stress distribution of the coil spring which concerns on 4th Embodiment, and the conventional coil spring. The graph showing the relationship of the number-of-turns position from the lower end of a coil spring and height concerning a 5th embodiment. The graph showing the relationship between the number-of-turns position from the lower end of the coiled spring of FIG. 10, and the coil inner radius. The figure which represented each stress distribution of the coiled spring of FIG. 10, and the conventional coiled spring. Sectional drawing of the strut type suspension apparatus provided with the coil spring which concerns on 6th Embodiment. 14 is a graph showing the relationship between the number of turns and the height from the lower end of the coil spring shown in FIG. 13. The graph showing the relationship between the number of turns from the lower end of the coil spring and the radius in the coil. The top view which looked at the same coil spring from the perpendicular direction. The figure showing each stress distribution of the same coiled spring and the conventional coiled spring.

  Hereinafter, a knee action type suspension apparatus 1 including a coil spring according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. The knee action type suspension system may be referred to as a link motion type.

  FIG. 1 schematically shows the suspension device 1. The suspension device 1 has a coil spring 2 and an arm member 3. The coil spring 2 has a wire 4 made of spring steel formed in a helical shape. The arm member 3 pivots up and down around a pivot (swing axis) 5. FIG. 1 shows a state in which the coil spring 2 is compressed to the full bump position. The “full bump” is a state in which the coil spring 2 is compressed to the maximum by a load.

  FIG. 2 shows a state in which the coil spring 2 is extended to the rebound position. "Rebound" is a state in which the coil spring 2 is maximally expanded when the vehicle body is lifted. The arm member 3 moves up and down around the pivot 5 according to the amount of compression of the coil spring 2. That is, the coil spring 2 expands and contracts between the full bump position shown in FIG. 1 and the rebound position shown in FIG. 2 to absorb the vibration transmitted from the road surface to the vehicle.

  A lower spring seat 10 is provided on the arm member 3. An upper spring seat 11 is provided above the lower spring seat 10. The spring seat 11 on the upper side is disposed on the lower surface of the member 12 constituting the vehicle body. The coil spring 2 is disposed in a compressed state between the lower spring seat 10 and the upper spring seat 11 and relatively biases the arm member 3 downward.

  When a compressive load is applied to the coil spring 2, the length of the coil spring 2 becomes shorter than the length in the free state. The coil spring 2 is effective between the lower side wound portion 20 supported by the lower side spring seat 10, the upper side wound portion 21 supported by the upper side spring seat 11, and the wound end portions 20 and 21. And 22. The number of turns of the end turn parts 20 and 21 is about 0.5 to 0.8.

  For example, the lower end portion 20 is from the lower end (lower terminal 4 a) of the strand 4 to, for example, around 0.7 turns. The upper end side winding portion 21 is from the upper end (upper terminal 4 b) of the wire 4 to, for example, around 0.8 turns. The effective portion 22 is a portion that functions effectively as a spring without winding portions of adjacent strands 4 in contact with each other in a full bump state in which the coil spring 2 is compressed to the maximum. The diameter (wire diameter) of the wire 4 is substantially constant in the end turns 20 and 21 and the effective portion 22.

  FIG. 3 shows the relationship between the number of turns from the lower terminal 4 a of the coil spring 2 and the height. Since the effective portion 22 of the coil spring 2 is wound at an equal pitch, the height linearly increases as the number of turns from the lower terminal 4a increases. The total number of turns of the coil spring 2 is 6.75, for example. However, the total number of turns other than this may be sufficient.

  FIG. 4 shows the relationship between the number of turns from the lower end 4 a of the coil spring 2 and the coil inner radius. The effective radius of the effective portion 22 is constant. Since the end turns 20 and 21 have a pigtail end shape, the coil inner radius changes according to the number of turns.

  FIG. 5 is a plan view of the coil spring 2 as viewed from the vertical direction (for example, from above). The vertical direction is a direction along the axis of the effective portion 22. C1 in FIG. 5 indicates the center of the coil spring 2. C2 in FIG. 5 indicates the central axis of rotation of the pivot 5. A line segment C <b> 3 connecting the center C <b> 1 of the coil spring 2 and the rotation center axis C <b> 2 extends in the longitudinal direction of the arm member 3.

  In FIG. 5, θ1 represents an angle that the line segment Y1 passing through the center C1 makes in the clockwise direction with respect to the extension line C3 ′ of the line segment C3. The lower terminal 4a is disposed on the opposite side of the rotation center axis C2, that is, on the side farthest from the pivot 5. Although the position of the upper end 4b is not necessarily limited to FIG. 5, when the total number of turns of the coil spring 2 is 6.75, the upper end 4b is disposed at the position of θ1 = 90 °.

  The solid line L1 in FIG. 6 shows the relationship between the number of turns of the wire 4 from the lower end 4a and the stress in the state where the coil spring 2 of the first embodiment is compressed to near the full bump position. As can be seen from FIG. 6, the coil spring 2 of the present embodiment has a stress peak portion P <b> 1 where the stress is maximal, in the vicinity of 3.5 turns from the lower end 4 a.

  In this specification, when the coil spring 2 is viewed from the vertical direction, the region corresponding to a total of 0.5 turns is defined as the first portion S1 by 0.25 turns on one side in the circumferential direction centered on the peak portion P1 of the stress. It is called. Also, the remaining area in the circumferential direction is referred to as a second portion S2. The second portion S2 is a region corresponding to a total of 0.5 turns, with 0.25 turns on one side opposite the stress peak part P1 across the coil center.

  The lower terminal 4a of this embodiment is located at a position (below the second portion S2) corresponding to the second portion S2 opposite to the stress peak portion P1 (FIGS. 1 and 2) Shown in). That is, in the coil spring 2 used for the knee action type suspension system 1, when a stress peak occurs on the side close to the pivot 5, the lower end 4a is on the side farthest from the pivot 5 (θ1 = 0 ° in FIG. 5). It is arranged to be located.

  The dashed-two dotted line L2 in FIG. 6 represents the relationship between the number of turns from the lower end of the conventional coil spring and stress. The total number of turns of the conventional coil spring is 6.75 like the coil spring of the first embodiment, and has a shape as shown in FIGS. However, the lower end of the conventional coil spring is disposed on the same side as the stress peak portion P2 (closer to the pivot 5), that is, on the position of θ1 = 180 ° in FIG. As shown by a two-dot chain line L2 in FIG. 6, the maximum stress of the conventional coil spring exceeds 1200 MPa, and the stress variation (difference between the maximum value and the minimum value) greatly fluctuates in the range of about 500 MPa. .

  On the other hand, in the coil spring 2 of the first embodiment, as shown by the solid line L1 in FIG. 6, the maximum stress is lowered to about 1020 MPa, and the stress variation is within the range of about 80 MPa. Thus, since the stress distribution is close to equalization, it is not necessary to design the wire diameter in accordance with the stress peak portion (high stress portion), and the weight can be reduced as compared with the conventional coil spring. Moreover, since the wire diameter of the wire 4 of the coil spring 2 of the present embodiment is substantially constant over the entire length, the stress can be reduced without using a special manufacturing technique (processing to change the wire diameter). It was possible.

  As shown in FIG. 1, in the state where the coil spring 2 is compressed to the full bump position, the length X1 in the coil axial direction of the portion near the pivot 5 of the coil spring 2 is the coil axis of the portion far from the pivot 5 It is larger than the direction length X2. In this compressed state, the number of wire winding portions 2a existing on the side closer to the pivot 5 is seven. On the other hand, the number of the wire winding portions 2b existing on the side far from the pivot 5 is six.

  That is, in a state where the coil spring 2 is compressed to the vicinity of the full bump position, the coil spring 2 is disposed in a portion having a longer length than the number of the wire winding portions 2b disposed in a portion having a small length in the coil axis direction. There are many strand winding parts 2a. As a result, in the state where the coil spring 2 is compressed to the vicinity of the full bump position, it is possible to reduce the variation in the pitch of the wire winding portions 2a and 2b between the side close to the pivot 5 and the side far from the pivot 5 . By this, in the state where the coil spring 2 is compressed to the full bump position, the occurrence of bending in the effective portion 22 is suppressed, and the substantially cylindrical shape is maintained.

  FIG. 7 shows respective stress distributions of the coil spring (total number of turns: 6.5) according to the second embodiment of the knee action type and the conventional coil spring (total number of turns: 6.5). A solid line L3 is a stress distribution in a state in which the coil spring according to the second embodiment is compressed, and a stress peak portion P3 where the stress becomes maximum exists around 3.5 turns from the lower end. When the effective portion is viewed from the vertical direction, a total of 0.5 turns is the first portion, with 0.25 turns on one side in the circumferential direction around the stress peak portion P3.

  The lower end of the second embodiment is disposed below the second portion opposite to the peak portion P3 of the stress, as in the coil spring of the first embodiment. That is, the coil spring is disposed such that the lower end is located on the side farthest from the pivot. Since the total number of turns of the coil spring of the second embodiment is 6.5, the upper end is disposed at a position close to the pivot (θ1 = 180 ° in FIG. 5).

  A two-dot chain line L4 in FIG. 7 indicates the stress distribution of the conventional coil spring. The lower end of the conventional coil spring is arranged on the second winding from the stress peak portion P4, that is, on the same side as the peak portion P4 (side closer to the pivot). The maximum stress of such a conventional coil spring has reached about 1300 MPa, and the variation of the stress varies greatly in the range of about 600 MPa. On the other hand, in the coil spring of the second embodiment, as shown by the solid line L3 in FIG. 7, the maximum stress is lowered to about 1100 MPa, and the stress variation is within the range of about 100 MPa.

  FIG. 8 shows respective stress distributions of the coil spring (total number of turns: 6.25) according to the third embodiment of the knee action type and the conventional coil spring (total number of turns: 6.25). A solid line L5 is a stress distribution in a state in which the coil spring according to the third embodiment is compressed, and a stress peak portion P5 where the stress becomes maximum is present around 3.4 turns from the lower end. When the effective portion is viewed from the vertical direction, a total of 0.5 turns is the first portion, with 0.25 turns on one side in the circumferential direction around the stress peak portion P5.

  The lower end of the third embodiment is disposed below the second portion opposite to the peak portion P5 of the stress, as in the coil spring of the first embodiment. That is, the coil spring is disposed such that the lower end is located on the side farthest from the pivot. Since the total number of turns of the coil spring of the third embodiment is 6.25, the upper end is disposed at an intermediate position (θ1 = 270 ° in FIG. 5) with respect to the pivot.

  The dashed-two dotted line L6 in FIG. 8 has shown stress distribution of the conventional coiled spring. The lower end of the conventional coil spring is disposed at the second turn from the peak portion P6 of the stress, that is, on the same side as the peak portion P6 (closer to the pivot). The maximum stress of such a conventional coil spring exceeds 1300 MPa, and the variation of the stress greatly fluctuates in the range of about 600 MPa. On the other hand, in the coil spring of the third embodiment, as shown by the solid line L5 in FIG. 8, the maximum stress is lowered to about 1100 MPa, and the stress variation is within the range of about 100 MPa.

  FIG. 9 shows the stress distribution of the coil spring (total number of turns: 6.0) and the conventional coil spring (total number of turns: 6.0) according to the fourth embodiment of the knee action type. A solid line L7 is a stress distribution in a state in which the coil spring according to the fourth embodiment is compressed, and a stress peak portion P7 where the stress becomes maximum is present in the vicinity of 2.4 turns from the lower end. When the effective portion is viewed from the vertical direction, 0.25 windings on one side in the circumferential direction centering on the stress peak portion P7, and a total of 0.5 windings is the first portion.

  The lower end of the fourth embodiment is disposed below the second portion opposite to the stress peak portion P7, as in the coil spring of the first embodiment. That is, the coil spring is arranged so that the lower end is located on the side farthest from the pivot. Since the total number of turns of the coil spring of the fourth embodiment is 6.0, the upper terminal is disposed at a position far from the pivot (θ1 = 0 ° in FIG. 5).

  A two-dot chain line L8 in FIG. 9 indicates the stress distribution of the conventional coil spring. The lower end of the conventional coil spring is disposed at the second turn from the peak portion P8 of the stress, that is, on the same side as the peak portion P8 (closer to the pivot). The maximum stress of such a conventional coil spring has reached 1400 MPa, and the variation in stress varies greatly in the range of about 600 MPa. On the other hand, in the coil spring of the fourth embodiment, as shown by the solid line L7 in FIG. 9, the maximum stress is reduced to 1200 MPa or less, and the stress variation is within the range of about 100 MPa.

  FIG. 10 shows the relationship between the number of turns and the height from the lower end of the unequal pitch coil spring according to the fifth embodiment of the knee action type. Since the effective portions of the coil spring are wound at unequal pitches, the height increases to a waveform (non-linear shape) as the number of turns from the lower end increases. The total number of turns of this coil spring is 6.75, for example. FIG. 11 shows the relationship between the number of turns from the lower end of the coil spring and the coil inner radius according to the fifth embodiment.

  FIG. 12 shows respective stress distributions of the coil spring (total number of turns: 6.75) and the conventional coil spring (total number of turns: 6.75) according to the fifth embodiment. A solid line L9 is a stress distribution in a state in which the coil spring of the present embodiment is compressed, and a stress peak portion P9 at which the stress becomes maximum exists in the vicinity of 3.5 turns from the lower end. When viewed from the vertical direction of the effective portion, the first portion is 0.25 windings on one side in the circumferential direction around the stress peak portion P9, for a total of 0.5 windings. The lower end of the present embodiment is disposed below the second portion opposite to the stress peak portion P9, as in the coil spring of the first embodiment. That is, the coil spring is disposed such that the lower end is located on the side farthest from the pivot.

  A two-dot chain line L10 in FIG. 12 indicates the stress distribution of the conventional coil spring. The lower end of the conventional coil spring is disposed at the second turn from the peak portion P10 of the stress, that is, on the same side as the peak portion P10 (closer to the pivot). The maximum stress of such a conventional coiled spring exceeds 1200 MPa, and the stress variation is greatly varied in the range of about 500 MPa. On the other hand, in the coil spring of the fifth embodiment, as shown by the solid line L9 in FIG. 12, the maximum stress is slightly higher than 1000 MPa, and the stress variation is in the range of about 100 MPa.

  FIG. 13 shows a strut type suspension device 101 provided with a coil spring 100 according to a sixth embodiment. The suspension system 101 includes a coil spring 100 and a strut 102 made of a shock absorber. The coil spring 100 has a wire 104 made of spring steel formed into a helical shape.

  The coil spring 100 is compressed between the lower side spring seat 110 and the upper side spring seat 111 to urge the strut 102 in the direction of the axis X0. The upper end of the strut 102 is attached to the vehicle body 113 via the mount insulator 112. A bracket 114 is provided below the strut 102. Mounted on the bracket 114 is a knuckle member 115 (only a part of which is shown) for supporting an axle. The strut 102 is attached to the vehicle body 113 in a state where the axis X0 is inclined at an upper end side inward of the vehicle by an angle θ2 with respect to the vertical line XL of gravity. The lower spring seat 110 moves relative to the upper spring seat 111 in the direction along the axis X0.

  The coil spring 100 is effective between the lower side wound portion 120 supported by the lower side spring seat 110, the upper side wound portion 121 supported by the upper side spring seat 111, and the wound end portions 120 and 121. And 122 are included. The diameter of the wire 104 (wire diameter) is substantially constant over the entire length of the coil spring 100.

  FIG. 14 shows the relationship between the number of turns from the lower terminal 104 a of the coil spring 100 and the height. Since the effective portion 122 of the coil spring 100 is wound at an equal pitch, the height linearly increases as the number of turns from the lower terminal 104a increases. The total number of turns of the coil spring 100 is, for example, 6.0. However, the total number of turns may be other than this.

  FIG. 15 shows the relationship between the number of turns from the lower end 104a of the coil spring 100 and the radius inside the coil. The effective radius of the effective portion 122 is constant. The end turns 120, 121 have a pigtail end configuration.

  FIG. 16 is a plan view of the coil spring 2 as seen from the vertical direction (for example, the upper side). C10 in FIG. 16 indicates the center of the coil spring 100. Θ3 in FIG. 16 indicates an angle formed by a line segment Y2 passing through the center C10 with respect to the line segment Z extending in the front-rear direction of the vehicle. The lower terminal 104a is disposed in the lower terminal support portion 130 located outside the vehicle (near θ3 = 108 °). When the total number of turns of the coil spring 100 is 6.0, the upper terminal 104b is disposed on the outer side of the vehicle similarly to the lower terminal 104a.

  FIG. 17 shows respective stress distributions of the coil spring 100 (total number of turns: 6.0) of the sixth embodiment and a conventional coil spring (total number of turns: 6.0). A solid line L11 is a stress distribution in a state in which the coil spring 100 is compressed, and a peak portion P11 of stress at which stress is maximum is present in the vicinity of 2.3 turns from the lower end. The effective portion 122 has a first portion S1 having a stress peak portion P11 and a second portion S2 opposite to the stress peak portion P11. When the effective portion is viewed in the vertical direction, the first portion S1 is a total of 0.5 turns 0.25 on each side in the circumferential direction around the stress peak portion P11.

  The lower end of the coil spring 100 is disposed below the second portion S2 opposite to the stress peak portion P11, as in the coil spring of the first embodiment. That is, in the strut type suspension system 101, the coil spring 100 is disposed such that the lower terminal 104a is located on the vehicle outer side.

  The dashed-two dotted line L12 in FIG. 17 has shown stress distribution of the conventional coiled spring (total number of turns: 6.0). The conventional coil spring has an effective portion and a wound portion shaped as shown in FIG. 14 and FIG. In the conventional coil spring, a peak portion P12 of stress exists near three turns from the lower end. The lower end of the conventional coil spring is disposed approximately on the third turn from the stress peak portion P12, that is, on the same side as the peak portion P12 (near θ3 = 290 ° in FIG. 16).

  As shown by a two-dot chain line L12 in FIG. 17, the maximum stress of the conventional coil spring is about 1190 MPa, and the variation of the stress fluctuates in the range of about 100 MPa. On the other hand, the maximum stress of the coil spring 100 of the present embodiment is reduced to about 1170 MPa, and the variation in stress is within the range of about 70 MPa. Thus, also in the strut type suspension device, the coil spring can be brought close to equal stress, and the weight of the coil spring can be reduced.

  In practicing the present invention, it goes without saying that the shape and number of turns of the coil spring, the position of the lower end, etc. can be changed without departing from the present invention, including the specific configuration of the suspension system.

  DESCRIPTION OF SYMBOLS 1 ... Suspension system, 2 ... Coil spring, 3 ... Arm member, 4 ... Wire | wire 4a ... Lower terminal, 4b ... Upper terminal, 5 ... Pivot, 10 ... Spring seat of a lower side, 10a ... Lower terminal support part, 11 ... Spring seat on the upper side, 20 ... Lower side coil, 21 ... Upper side coil, 22 ... Effective part, 100 ... Coil spring, 101 ... Suspension device, 104 ... Wire, 104a ... Lower end, 120 ... Lower side coiled portion 121 Upper side coiled portion 122 Effective portion 130 Lower terminal support portion P1, P3, P5, P7, P9, P11 Stress peak portion S1 First portion S2 ... second part.

Claims (6)

A lower side winding portion supported by a lower spring seat, an upper side winding portion supported by an upper spring seat, and the lower side winding portion, which is made of a strand formed in a spiral shape. A coil spring having an effective portion between the upper side end winding portion,
In a state where the coil spring is compressed and a stress is generated on the wire,
The first portion having the stress peak portion in the circumferential direction of the effective portion, and the second portion on the opposite side of the circumferential direction to the stress peak portion, and
The coil spring characterized in that the lower side wound portion includes a lower end disposed below the second portion.   The coil spring according to claim 1, wherein the effective portion has a substantially cylindrical shape and an equal pitch, and a peak portion of the stress is provided in a part of a circumferential direction of the effective portion.   The coil spring according to claim 1, wherein the pitch of the effective portion is an unequal pitch, and a peak portion of the stress is provided in a part of the circumferential direction of the effective portion.   The wire spring according to claim 2 or 3, wherein a wire diameter is constant over the entire length of the effective portion. An arm member pivoting up and down about a pivot;
A coil spring comprising a strand formed in a spiral shape, arranged in a compressed state between a lower spring seat and an upper spring seat, and biasing the arm member;
It is a knee action type vehicle suspension system having
The coil spring is
A lower side wound portion supported by the lower side spring seat;
An upper side wound portion supported by the upper side spring seat;
Having an effective portion between the lower side winding part and the upper side winding part,
In a state where the coil spring is compressed and a stress is generated on the wire,
The first portion having the stress peak portion in the circumferential direction of the effective portion, and the second portion on the opposite side of the circumferential direction to the stress peak portion, and
A suspension system for a vehicle, comprising: the lower end wound portion includes a lower terminal disposed below the second portion remote from the pivot. Struts that expand and contract in a direction along the axis,
A coil spring formed of a helically formed strand and disposed in a compressed state between the lower side spring seat and the upper side spring seat, and biasing the strut in a direction along the axis;
And a strut type vehicle suspension system having
The coil spring is
A lower side wound portion supported by the lower side spring seat;
An upper side wound portion supported by the upper side spring seat;
Having an effective portion between the lower side winding part and the upper side winding part,
In a state where the coil spring is compressed and a stress is generated on the wire,
The first portion having the stress peak portion in the circumferential direction of the effective portion, and the second portion on the opposite side of the circumferential direction to the stress peak portion, and
A suspension system for a vehicle, comprising: the lower end wound portion includes a lower terminal disposed below the second portion outside the vehicle.

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