JP5769499B2 - Coil spring - Google Patents

Description

  The present invention relates to a coil spring used for a torsion spring or the like of a torsional vibration attenuator.

  2. Description of the Related Art Conventionally, some torsion springs used for clutch disks have a flat surface as a molding contact surface on the outer peripheral shape of a circular cross section of a spring wire wound in a coil shape. In this coil spring, when a load is applied to the coil until the coil shape is in a close contact state or a locked state, the flat surface comes into contact with the adjacent coil portion to stably receive the load and suppress deviation in the coil radial direction. be able to.

  However, in general, in the coil spring, the stress on the inner diameter side (coil inner diameter side portion) with respect to the coil shape of the spring wire is higher than the stress on the outer diameter side (coil outer diameter side portion). Furthermore, by providing the flat surface, the stress dispersion state in the circumferential direction of the spring element wire is further influenced together with the bias of the stress.

  On the other hand, when a flat surface is provided on the spring wire, if the flatness of the cross-sectional shape is reduced, the contact length in the coil axis direction when the flat surface abuts can be shortened, and the low rigidity of the stroke is long. It is also advantageous in designing the spring.

  FIG. 13 is a graph showing the relationship between the spring index D / W and the stress ratio due to the difference in flatness ratio T / W, and FIG. 14 shows the spring index D / W and the contact height ratio due to the difference in flatness ratio T / W. 15 to 18 are sectional stress distribution diagrams showing the analysis results of the stress distribution state by the finite element method in the cross section of the spring element wire in the conventional coil spring.

  Referring to the reference numeral of the spring element wire 101 in FIG. 15, T is the maximum dimension in the coil axial direction, W is the maximum dimension in the coil radial direction, and D is the coil center diameter.

  FIG. 13 confirms the stress ratio with a constant spring constant and a close contact height when a flat surface is provided on a spring wire having a circular cross section. FIG. 14 shows the contact height ratio with the spring constant and the stress being constant in the case where the flat surface is provided on the spring wire having a circular cross section. In both FIG. 13 and FIG. 14, the change in stress with respect to the spring index D / W when the flat rate T / W = 0.92 is 1, and the flat rate T / W = 0 with respect to this flat rate T / W = 0.92. The stress ratio and the contact height ratio of the .76 coil spring were confirmed.

  As shown in FIGS. 13 and 14, when the flattening rate T / W = 0.76 with respect to the flattening rate T / W = 0.92, both the stress ratio and the contact height became small.

  The spring element wire 101 in FIG. 15 has a flat cross section 103 formed by drawing or the like on a circular cross section serving as a base, and a flattening ratio T / W = 0.92. The spring element wire 105 in FIG. 16 has a flat cross-section 107 formed by drawing or the like in a circular cross section serving as a base, and a flatness ratio T / W = 0.76.

  As is clear from comparison between FIGS. 15 and 16, in the spring element wires 101 and 105 having a circular base, the stress on the coil inner diameter side portion 109 is distributed to the flat surfaces 103 and 107 by forming the flat surfaces 103 and 107. is made of. However, in the case of a circular cross section, when the flattening ratio T / W is small, stress distribution in the circumferential direction is achieved, but the continuity of the stress distribution is reduced, and the flattening ratio is formed by forming the flat planes 103 and 107. There is a limit to making the stress uniform by reducing T / W.

  The spring element wire 111 in FIG. 17 is formed in a rectangular cross section. In the case of the spring wire 111 having the rectangular cross section, the stress of the coil inner diameter side portion 109 can be dispersed and the load can be stably received in the close contact state, as in FIGS. 15 and 16. It is.

  However, in the case of the spring element wire 111 of FIG. 17 as well, the continuity of the stress dispersion is lower than that of the example of FIG. 16 where the same flatness ratio T / W = 0.76.

  That is, in a conventional coil spring in which a flat surface is provided on a spring wire having a circular cross section or a rectangular cross section, the load is stably received in a close contact state, the flatness is reduced to reduce the close contact length, and the cross sectional shape is reduced. There was a limit to improving the uniformity of the stress distribution due to the continuity of stress distribution in the circumferential direction.

On the other hand, the spring element wire 113 of FIG. 18 has a coil inner diameter side portion 115 having a super-elliptical shape with a major axis = a and a minor axis = b represented by (x / a) ^α + (y / b) ^α = 1. The value of α is in the range of α = 1.8 to 2.45, and the coil outer side portion 117 has a circular shape of x ² + y ² = 1. The flatness is T / W = 0.76 In this spring element wire 113, both the stress ratio and the contact height are small, and the continuity of stress dispersion is also improved.

  However, in the case of this spring element wire 113, the contact form of the flat surface 119 is unambiguous, and if the flat surfaces 119 are inclined, there is a problem that the sitting at the time of contact is not stable.

  In addition, when the coil is curved, there is also a problem that the inclination of each flat surface 119 must be set according to the curvature of the coil.

  Further, since the flat surfaces 119 are in contact with each other, there is a problem in that lateral displacement in the coil radial direction is likely to occur.

JP-A-6-300065 2008-185072

  The problem to be solved is that, in the conventional coil spring provided with a molding contact surface on the spring element wire, the load is stably received in a close contact state, the flatness is reduced to shorten the close contact length, and the cross section There is a limit to improving the uniformity of the stress distribution due to the continuity of the stress dispersion in the circumferential direction of the shape, and it is easy to cause a lateral shift.

The present invention stably receives a load in a close contact state and reduces the flattening ratio to shorten the contact length, and improves the uniformity of the stress distribution by the continuity of the stress distribution in the circumferential direction of the cross-sectional shape, In order to suppress the lateral displacement, the coil outer diameter side portion and the coil inner diameter side portion are expressed by (x / a) ^α + (y / b) ^α = 1 with respect to the outer peripheral shape of the cross section of the spring wire wound in the coil shape. A coil spring having a major axis = a and a minor axis = b, and a value of α in the range of α = 2 to 3, wherein the spring element wire has a concave and convex shape on one side in the coil axial direction. A contact arc is provided, and a convex arc contact portion is provided on the other side. The concave and convex contact portion includes a concave portion having a cross sectional arc shape, a pair of cross sectional arc shapes continuous to both sides of the concave portion and the inner and outer diameter side portions of the coil. Provided with a convex portion, and the coil portion adjacent to the pair of convex portions in the coil axial direction. Arc-shaped abutting portion abuts, characterized in that the coils are in close contact.

  Since the coil spring according to the present invention has the above-described configuration, it improves the uniformity of stress distribution between the coil outer diameter side portion, the coil inner diameter side portion, the concavo-convex portion, and the convex arc-shaped contact portion, and the outer circumferential convex curved surface in a tight contact state Is in contact with the convex portion, the contact state is stabilized, and the load can be stably received. Moreover, since the convex arc contact portion is fitted into the concave portion, so-called lateral deviation in the coil radial direction can be suppressed.

It is a front view of a coil spring. (Example 1) It is a principal part expanded sectional view which shows close_contact | adherence of a spring strand. (Example 1) It is a principal part expanded sectional view which shows close_contact | adherence of a spring strand. (Example 1) It is a principal part expanded sectional view which shows the shape of a spring strand. (Example 1) It is a principal part expanded sectional view which shows the shape of a spring strand. (Example 1) It is a principal part expanded sectional view which shows close_contact | adherence of a spring strand. (Example 1) It is a principal part expanded sectional view which shows close_contact | adherence of a spring strand. (Example 1) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Example 1) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Comparative Example 1) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Comparative Example 2) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Comparative Example 3) It is a graph which shows the relationship between contact | adherence length and body load stress ratio. (Example 1) It is a graph which shows the relationship between the spring index D / W and stress ratio by the difference in flatness ratio T / W. (Conventional example) It is a graph which shows the relationship between the spring index D / W by the difference in flatness ratio T / W, and contact | adherence height ratio. (Conventional example) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Conventional example) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Conventional example) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Conventional example) It is a cross-sectional stress distribution diagram which showed the analysis result of the stress distribution state by the finite element method. (Conventional example)

The load is stably received in close contact, the flatness is reduced to shorten the contact length, and the stress distribution uniformity is improved by the continuity of the stress distribution in the circumferential direction of the cross-sectional shape, thereby suppressing lateral deviation. For the purpose of making it possible, the outer diameter side portion and the inner diameter side portion of the coil are represented by (x / a) ^α + (y / b) ^α = 1 expressed by a curved shape with a major axis = a and a minor axis = b A coil spring in which the value of α is in the range of α = 2 to 3, wherein a concave and convex contact portion is provided on one side of the coil axis direction of the spring element wire, and a convex arc contact is provided on the other side. Realized by providing a part.

[Coil spring]
1 is a front view of a coil spring according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a main part showing the close contact of the spring wire, and FIG. 3 is an enlarged cross-sectional view of the main part showing the close contact of the spring wire. FIG. 4 is an enlarged cross-sectional view of the main part showing the shape of the spring wire.

  The coil spring 1 of FIG. 1 is for example in a torsional damper (torsional vibration attenuator) of a friction disk (designed) for a dual mass flywheel or lock-up for a torque converter or for a wet or dry clutch mechanism. The spring element wire 3 is wound in a coil shape. This coil spring 1 has a coil axis 5 in an arc shape in a free state, and this arc shape has a radius of curvature R in an assembled state.

As shown in FIGS. 2 to 4, the spring element wire 3 of the coil spring 1 is configured such that the inner and outer diameter side portions 7 and 9 of the coil are represented by (x / a) ^α + (y / b) ^α = 1 It is a super-elliptical shape that is a curved shape with a minor axis = b. The value of α was in the range of α = 2 to 3.

  Assuming that the maximum dimension T in the coil axis direction and the maximum dimension W in the coil radial direction are set, the flatness ratio T / W = 0.76 is set in this embodiment. However, the aspect ratio T / W can be selected in the range of 0.5 to 0.95.

  An uneven contact portion 11 is provided on one side of the spring element wire 3 in the coil axis direction, and a convex arc contact portion 13 is provided on the other side.

  FIG. 5 is an enlarged cross-sectional view of the main part showing the shape of the spring wire.

  As shown in FIG. 5, the concave and convex contact portion 11 includes a concave portion 15 and a pair of convex portions 17 and 19. The recess 15 is formed in a cross-sectional arc shape, for example, a cross-sectional arc shape having a radius r1. The radius r1 is set larger than W / 2, for example. The convex portions 17 and 19 are formed in a cross-sectional arc shape continuous to both sides of the concave portion 15 and the inner and outer diameter side portions 7 and 9 of the coil, for example, a cross-sectional arc shape having a radius r2. The radius r2 is such that both sides of the recess 15 and the inner and outer diameter side portions 7 and 9 of the coil are smoothly continuous.

  As shown in FIGS. 2 and 3, the convex arc-shaped contact portion 13 of the coil portion adjacent to the pair of convex portions 17 and 19 in the direction of the coil axis 5 comes into contact, and the coil comes into close contact. In this tight contact state, the convex arc-shaped contact portion 13 can be fitted into the concave portion 15 to suppress a so-called lateral shift in the coil radial direction.

  Compared with the case where the convex arc 21 having the same degree of curvature as that of the concave portion 15 is formed, this close contact state can shorten the mutual interval in the range of S, and accordingly, the close contact height of the coil spring is lowered. be able to.

  A gap is formed between the contact between the concave portion 15 and the convex arc-shaped contact portion 13 when the coil is in close contact. By forming this gap, the pair of convex portions 17 and 19 can reliably come into contact with the convex arc-shaped contact portion 13, and the sitting at the time of close contact can be reliably stabilized.

  The angle θ between the closely contacting coil portions corresponds to the arc shape of the coil axis 5, but the convex portions 17 and 19 and the convex arc-shaped contact portion 13 can be reliably connected even if the respective angle θ between the coil portions is slightly deviated. Can abut.

  FIG. 6 is an enlarged cross-sectional view of the main part showing the close contact of the spring wire, and FIG. 7 is an enlarged cross-sectional view of the main part showing the close contact of the spring wire.

  6 and 7 show the close contact when the coil axis of the coil spring 1A is straight. As shown in FIGS. 6 and 7, even when adjacent coil portions are slightly inclined at the time of coil formation, the convex portions 17 and 19 and the convex arc-shaped contact portion 13 can be reliably in contact with each other.

[Stress distribution]
8 to 11 are analysis results of the stress distribution state by the finite element method, FIG. 8 is a sectional stress distribution diagram of this example, and FIGS. 9 to 11 are sectional stress distribution diagrams of Comparative Examples 1 to 3. It is.

  8 to 11 are all designed with respect to the coil outer diameter φ19 and are stress (MPa / N) with respect to a load of 1N.

  In the embodiment of FIG. 8, in the spring wire 3, the stress on the coil inner diameter side portion 7 is applied to the uneven contact portion 11 and the convex arc contact portion 13 by forming the uneven contact portion 11 and the convex arc contact portion 13. It was able to disperse continuously. The maximum stress of the coil inner diameter side portion 7 was 0.9500 (MPa / N). Moreover, the stress of the convex parts 17 and 19 with which the convex arc-shaped contact part 13 abuts can be made lower than the stress of the concave part 15, and the durability can be improved against repeated close contact.

  Comparative example 1 in FIG. 9 is of a spring element wire 3A having a circular cross section, and the maximum stress on the inner diameter side was 0.9681 (MPa / N) due to stress dispersion.

  In Comparative Example 2 of FIG. 10, the base is of the spring element wire 3B having a circular cross section, and the stress distribution is not sufficient due to the formation of the concave contact portion 11B, and the maximum stress of the coil inner diameter side portion 7B is 1.027 (MPa / N).

  The stress in the contact portion 11B where the arc surface of the adjacent coil portion is fitted and contacted is larger than the convex portions on both sides thereof.

In Comparative Example 3 of FIG. 11, the coil inner diameter side portion 7 </ b> C is a super ellipse having a major axis = a and a minor axis = b represented by (x / a) ^α + (y / b) ^α = 1, and the value of α is , Α = 1.8 to 2.45, and the coil outer side portion 9C has a circular shape of x ² + y ² = 1.
In Comparative Example 3, the continuity of stress dispersion was maintained from the coil inner diameter side portion 7C to the flat surface 11C, and the maximum stress of the coil inner diameter side portion 7C was 0.9542 (MPa / N).

  A high stress portion was present on the flat surface 11C where the flat surfaces of adjacent coil portions abut.

  Compared to Comparative Examples 1 to 3, the coil spring 1 of the embodiment of the present invention can minimize the maximum stress of the coil inner diameter side portion 7 by stress distribution, can maintain the continuity of stress distribution, and adjacent coils. The stress of the convex parts 17 and 19 with which the convex arc-shaped contact part 13 of the part abuts can be reduced, and the durability can be improved against repeated close contact.

[Adhesion length and stress ratio]
FIG. 12 is a graph showing the relationship between the adhesion length and the body load stress ratio.

  In FIG. 12, the plotted points are those of the embodiment of the present invention, and are outside the range of the vertical and horizontal straight lines. It becomes the comparative example 2 level. As is apparent from FIG. 12, in comparison with Comparative Example 2, both the adhesion length and the stress ratio could be reduced.

[Effect of Example]
With respect to the cross-sectional outer peripheral shape of the spring wire 3 wound in a coil shape, the coil outer diameter side portion 9 and the coil inner diameter side portion 7 are represented by (x / a) α + (y / b) α = 1, the long diameter = a, A coil spring having a super-elliptical shape with a minor axis = b and a value of α in a range of α = 2 to 3, and an uneven contact portion 11 is provided on one side of the spring element wire 3 in the coil axis 5 direction. On the other side, a convex arc-shaped contact portion 13 is provided. The concave-convex contact portion 11 includes a concave section 15 having a cross-section arc shape, a pair of cross-section arc shapes continuous to both sides of the concave section 15 and the inner and outer diameter side portions 7 and 9 of the coil. The convex arc-shaped abutting portions 13 of the coil portions adjacent to the pair of convex portions 17 and 19 in the direction of the coil axis 5 come into contact with the pair of convex portions 17 and 19 so that the coils are in close contact with each other.

  For this reason, it becomes easy to obtain a sufficient quality for designing a low-rigidity spring with a long stroke required for a coil spring for a torsion damper. Further, it is possible to easily improve the filter function for reducing the occurrence of noise and vibration in the dynamic state. This function is required for a torsional damper (torsional vibration damper) assembled in an engine system.

  In addition, it is possible to reduce the stress of the convex portions 17 and 19 with which the convex arc-shaped abutting portion 13 abuts and improve the durability.

  The maximum dimension in the coil axis direction of the outer peripheral cross section of the spring wire 3 was T, the maximum dimension in the coil radial direction was W, and the flatness ratio T / W was 0.5 to 0.95.

  For this reason, both the adhesion length and the stress ratio can be reduced.

  Since the uneven contact portion 11 and the convex arc contact portion 13 are brought into contact with each other, a load in the direction of the coil axis 5 in the coil contact state can be reliably received, and displacement in the coil radial direction can be reliably suppressed. it can.

  The uneven contact portion 11 and the convex arc contact portion 13 can reliably receive a load in the direction of the coil axis 5 even when the coil axis 5 has an arc shape, and reliably shift in the coil radial direction. Can be suppressed.

  The coil inner and outer diameter side portions 7 and 9 are curved super-elliptical shapes, and are provided with the concave and convex contact portion 11 and the convex arc-shaped contact portion 13, thereby reducing the flatness and shortening the contact length and the cross-sectional shape. The uniformity of stress distribution can be improved by the continuity of the stress dispersion in the circumferential direction.

  Since the coil axis of the spring element wire 3 is in a free state and the coil axis is an arc, the coil axis 5 can be easily assembled into an arc.

  The coil shape of the spring wire 3 can also be set to a shape having the curvature radius R of the coil axis 5 in the assembled state. In this case, the uneven contact portion 11 and the convex arc contact portion 13 contact according to the curvature of the coil axis 5.

  The coil spring 1 can be assembled to a torsional damper (torsional vibration absorber) of a dual mass flywheel or a lock-up for a torque converter or a wet or dry clutch mechanism. For this reason, it is possible to apply a coil spring having a long stroke and a low rigidity.

1, 1A coil spring 3 spring element wire 5 coil axis 7 coil inner diameter side portion 9 coil outer diameter side portion
11 Uneven contact part
13 Convex arc contact part
15 recess
17, 19 Convex

Claims (7)

For the outer peripheral shape of the cross section of the spring wire wound in the coil shape,
The coil outer diameter side portion and the coil inner diameter side portion are formed into a curved shape with a major axis = a and a minor axis = b represented by (x / a) ^α + (y / b) ^α = 1,
A coil spring in which the value of α is in the range of α = 2 to 3,
On the one side in the coil axial direction of the spring element wire, an uneven contact portion is provided, and on the other side, a convex arc contact portion is provided,
The concave-convex contact portion includes a concave portion having an arc-shaped cross section and a pair of convex portions having an arc-shaped cross section that are continuous with both sides of the concave portion and the inner and outer diameter side portions of the coil,
The convex arc contact portion of the coil portion adjacent to the pair of convex portions in the coil axis direction comes into contact with the coil,
A coil spring characterized by that. The coil spring according to claim 1,
The maximum dimension in the coil axis direction of the outer peripheral cross section of the spring element wire is T, and the maximum dimension in the coil radial direction is W,
Flatness ratio T / W = 0.5 to 0.95,
A coil spring characterized by that. The coil spring according to claim 1 or 2,
The concavo-convex portion is continuous in an arc shape in cross section,
A coil spring characterized by that. The coil spring according to any one of claims 1 to 3,
Between the contact between the concave portion and the convex arc-shaped contact portion, a gap is formed at the time of coil contact,
A coil spring characterized by that. The coil spring according to any one of claims 1 to 4,
The coil shape of the spring element wire is a free state in which the coil axis is arcuate,
A coil spring characterized by that. The coil spring according to any one of claims 1 to 5,
The coil shape of the spring element wire is an arc shape having a radius of curvature when the coil axis is assembled. The coil spring according to any one of claims 1 to 6,
A coil spring characterized by being assembled in a torsional damper (torsional vibration damper) of a friction disk for a dual mass flywheel or a lock-up for a torque converter or a wet or dry clutch mechanism.