JP5827637B2 - 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;
FIG. 14 is a graph showing the relationship between the spring index D / W and the contact height ratio due to the difference in the flatness ratio T / W. 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.

  In FIG. 13, when the flat surface is provided on the spring wire having a circular cross section, the spring constant and the contact height are made constant, and the stress ratio is confirmed. In FIG. 14, in the case where a flat surface is provided on a spring wire having a circular cross section, the spring constant and the stress are constant and the contact height ratio is confirmed. 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 and the contact height were reduced.

  FIGS. 15 and 16 are explanatory views showing the analysis result of the stress distribution state by the finite element method in the cross section of the spring wire in the conventional coil spring. The spring element wire 101 is formed by forming a flat surface 103 on a circular cross-section serving as a base by drawing or the like to have a flatness ratio T / W = 0.92. The spring element wire 105 is formed by forming a flat surface 107 on a circular cross-section serving as a base by drawing or the like to obtain a flatness ratio T / W = 0.76.

  As is clear from comparison between FIGS. 15 and 16, in the spring elements 101 and 105 having a circular base, the stress on the coil inner diameter side portion 108 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.

  FIG. 17 shows the analysis result of the stress distribution state by the finite element method, similarly to FIGS. 15 and 16. The spring wire 109 is formed in a rectangular cross section. Also in the case of the spring wire 109 having this rectangular cross section, the stress of the coil inner diameter side portion 108 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 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.

JP-A-6-300065 JP 10-82440 A

  The problem to be solved is that in the conventional coil spring having a formed contact surface on the spring 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.

The present invention makes it possible to stably receive a load in a close contact state, shorten the contact length by reducing the flatness ratio, and further improve the uniformity of stress distribution by the continuity of stress distribution in the circumferential direction of the cross-sectional shape. In order to reduce the surface pressure at the time of close contact without increasing the coil outer diameter, the coil outer diameter side portion is defined as x ² + y ² = b ² with respect to the outer peripheral shape of the cross section of the spring wire wound in the coil shape. The coil spring has a semicircular shape represented by the following formula, and the coil inner diameter side portion is a non-circular shape having a major axis = a and a minor axis = b represented by (x / a) ^α + (y / b) ^α = 1. And between the inner and outer diameter side portions of the outer peripheral cross-sectional shape of the spring element, a forming contact surface capable of contacting a coil portion adjacent in the coil axial direction is provided across the semicircular shape and the non-circular shape, T: Maximum dimension in the coil axis direction between the molding contact surfaces, W: front The maximum dimension in the coil radial direction of the spring element wire, and the ratio of the stress ratio with a constant spring constant and constant contact height and the ratio of contact height with constant spring constant and constant stress to the spring element wire with a circular cross section The flatness is 0.6 ≦ T / W ≦ 0.76, and the value of α is set to α = 1.85 to 2.45 so as to be lower than that of a coil spring provided with a flat surface of 0.92. The stress in the coil inner diameter side portion is continuously distributed to the forming contact surface .

The present invention stably receives a load in a close contact state, shortens the flattening rate to shorten the close contact length, and further improves the uniformity of the stress distribution by the continuity of the stress distribution in the circumferential direction of the cross-sectional shape. Therefore, for the outer peripheral cross-sectional shape of the spring wire wound in the coil shape, the coil outer diameter side portion is a semicircular shape represented by x ² + y ² = b ² , and the coil inner diameter side portion is (x / a) ^α + (y / b) ^α is a non-circular coil spring having a major axis = a and a minor axis = b represented by ^α = 1, and is between the coil inner and outer diameter side portions of the outer circumferential shape of the spring element wire, Forming contact surfaces capable of contacting coil portions adjacent to each other in the coil axial direction are provided across the semicircular shape and the non-circular shape, T: maximum dimension in the coil axial direction between the forming contact surfaces, W: the above The maximum dimension in the coil radial direction of the spring element wire The ratio of the stress with constant and constant contact height and the ratio of contact height with constant spring constant and constant stress are compared with a coil spring in which a flat wire with a flatness ratio of 0.92 is provided on a spring wire having a circular cross section. Therefore, the flatness is 0.6 ≦ T / W ≦ 0.76, the value of α is in the range of α = 1.85 to 2.45, and the stress on the inner diameter side of the coil is formed and contacted. Since the surface is continuously distributed to the surface, the load is stably received by the molding contact surface, the flatness is reduced to shorten the contact length, and the stress is distributed in the circumferential direction of the outer peripheral shape of the cross section. Due to this continuity, the uniformity of the stress distribution can be further improved.

(Example 1) which is a front view of a coil spring. It is a principal part expanded sectional view by the side of a coil shape inner diameter (reference example). It is an expanded sectional view of a spring strand (reference example). It is explanatory drawing which shows the outer periphery basic shape used for the cross section of a spring strand (reference example). It is explanatory drawing which showed the analysis result of the stress distribution state by a finite element method (reference example). It is explanatory drawing which showed the analysis result of the stress distribution state by a finite element method (Example 1). It is a graph which shows the relationship between the spring index D / W and stress ratio by the difference in a base (Example 1). It is a graph which shows the relationship between the spring index D / W by the difference in a base, and contact | adherence height ratio (Example 1). It is a graph which shows the relationship between the spring index D / W and weight ratio by the difference in a base (Example 1). It is a graph which shows the relationship between flattening rate T / W by the difference in spring index D / W, and stress ratio (Example 1). It is a graph which shows the relationship between flatness ratio T / W by the difference in spring index D / W, and contact | adherence height ratio (Example 1). (Example 1) which is a graph which shows the change of the stress ratio when the value of (alpha) is changed about the case where a base is a spring strand by the side of a semicircle outer part. It is a graph which shows the relationship between the spring index D / W by the difference in flatness ratio T / W, and a stress ratio ( confirmation 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 ( confirmation example ). It is explanatory drawing which showed the analysis result of the stress distribution state by a finite element method (conventional example). It is explanatory drawing which showed the analysis result of the stress distribution state by a finite element method (conventional example). It is explanatory drawing which showed the analysis result of the stress distribution state by a finite element method (conventional example).

The load is stably received in close contact, the flatness is reduced to shorten the close contact length, and the stress distribution uniformity is simultaneously achieved by the continuous stress distribution in the circumferential direction of the cross-sectional shape. The object of the semicircular coil outer diameter side represented by x ² + y ² = b ² and the major axis = a and minor axis represented by (x / a) ^α + (y / b) ^α = 1 This was realized by providing a molding contact surface in a semicircular shape and a noncircular shape on the outer peripheral shape of the cross section formed by the non-circular coil inner diameter side portion of b.

[Coil spring]
1 is a front view of a coil spring according to Embodiment 1 of the present invention, FIG. 2 is an enlarged cross-sectional view of a main part on the inner diameter side of a coil shape according to a reference example of the present invention, and FIG. FIG. 4 is an enlarged cross-sectional view, and FIG. 4 is an explanatory view showing the outer peripheral basic shape used for the cross section of the spring element wire according to the reference example.

  1 is for example a dual mass flywheel or a torque converter lock-up or in a friction disk torsional damper (torsional vibration damper) for (designed as) a wet or dry clutch mechanism. The spring element wire 3 is wound in a coil shape. The coil spring 1 has a coil axis 4 having an arc shape in a free state, and the arc shape has a radius of curvature R in an assembled state.

2 to 4, the spring element wire 3 of the coil spring 1 includes a semicircular coil inner diameter side portion 5 represented by x ² + y ² = b ² and (x / a) ^α + (y / b ) The major axis represented by ^α = 1 = a,
In contrast to the outer peripheral basic shape (FIG. 4) composed of the non-circular coil outer diameter side portion 7 with the short diameter = b, flat surfaces 9 and 11 are provided as forming contact surfaces. The value of α was in the range of α = 1.85 to 2.45.

  The flat surfaces 9 and 11 are provided on both sides in the coil axis direction of the cross-sectional shape of the spring element wire 3, and are inclined with respect to each other so that the cross-sectional shape of the spring element wire 3 is wedge-shaped as shown in FIGS. ing. In the present reference example, the inclination of the flat surfaces 9 and 11 is along the radius of curvature of the arc shape of the coil spring 1. The width H of the flat surfaces 9 and 11 depends on the flat rate T / W, and is set to T / W = 0.76 in this reference example.

  The flatness ratio can be advantageously selected in relation to the stress ratio and the contact height in the range of 0.6 ≦ T / W ≦ 0.76 from FIGS. 10, 11, and 12 described later. When T / W ≦ 0.76, the base of FIGS. 6, 16, and 17 reaches the flat surfaces 9 and 11 in the coil inner diameter side portion 5 and maintains the continuity of the stress distribution by comparing the circular cross section and the rectangular cross section. The range was made.

  The flat surfaces 9 and 11 have a mutual angle θ and a maximum dimension T of the semicircular coil inner diameter side portion 5 by the flatness ratio T / W and the inclination setting. The mutual angle θ is centered on the center of curvature of the coil spring 1.

[Stress distribution]
FIG. 5 is an explanatory diagram showing an analysis result of a stress distribution state by a finite element method according to a reference example. As shown in FIG. 5, in the spring wire 3, the stress of the coil inner diameter side portion 5 can be continuously distributed to the flat surfaces 9 and 11 by forming the flat surfaces 9 and 11. As apparent from the comparison with the example of FIG. 15 having the same aspect ratio T / W = 0.92 , the reference example of FIG. 5 was able to reliably achieve a uniform and continuous distribution of stress while reducing the aspect ratio. .

  The shapes of the inner and outer diameter side portions 5 and 7 of the coil can be reversed.

FIG. 6 relates to Example 1 of the present invention, and shows an analysis result of a stress distribution state by a finite element method when the coil outer diameter side portion 7 has a semicircular shape and the coil inner diameter side portion 5 has a noncircular shape. FIG. That is, in the spring element wire 3A of FIG. 6, the coil outer diameter side portion 7 has a semicircular shape represented by x ² + y ² = b ² , and the coil inner diameter side portion 5 becomes (x / a) ^α + (y / b) A non-circular base shape having a major axis = a and a minor axis = b represented by ^α = 1, and flat surfaces 9 and 11 as molding contact surfaces are provided on the outer peripheral surface with respect to the outer base shape. ing.

  Since the flat surfaces 9 and 11 are provided in a semicircular shape and a non-circular shape, the flat surfaces 9 and 11 can be expanded toward the coil inner diameter side without affecting the coil outer diameter. For this reason, it is possible to reduce the surface pressure in the close contact state and stably receive the load.

  As shown in FIG. 6, even with this spring element wire 3A, it was possible to reliably achieve a uniform and continuous distribution of stress while reducing the flatness. Moreover, a more continuous and uniform dispersion can be achieved than in the reference example of FIG.

Note that the present applicant has already proposed a coil spring having the outer peripheral basic shape of FIG. 6 (Japanese Patent Publication No. 6-23583).

[Stress ratio, contact height ratio, weight ratio]
FIG. 7 is a graph showing the relationship between the spring index D / W and the stress ratio due to the difference in the outer peripheral base shape (base), and FIG. 8 shows the relationship between the spring index D / W and the contact height ratio due to the difference in the base. FIG. 9 is a graph showing the relationship between the spring index D / W and the weight ratio due to the difference in base, and FIG. 10 is the graph showing the relationship between the flatness ratio T / W and the stress ratio due to the difference in the spring index D / W. FIG. 11 is a graph showing the relationship between the flatness ratio T / W and the contact height ratio due to the difference in the spring index D / W.

  7 to 9, the outer peripheral basic shape (base) is a circle, rectangle, semicircular inner diameter side (cross-sectional shape in FIG. 5), and semicircular outer diameter side (cross-sectional shape in FIG. 6). In the case where a flat surface is provided, in FIG. 7, the spring constant and the contact height are constant, and the stress ratio is confirmed for the flat rate T / W = 0.76. In FIG. 8, the contact height ratio was confirmed for the flat rate T / W = 0.76, with the spring constant and stress being constant. In FIG. 9, the weight ratio was confirmed with respect to the flatness ratio T / W = 0.76, with the spring constant and stress being constant. In any of FIGS. 7 to 9, when the flatness is T / W = 0.76 and the base is a circle, the base is rectangular, the semicircular inner diameter side (cross-sectional shape in FIG. 5), and the semicircular outer diameter. For each spring element on the side (cross-sectional shape in FIG. 6), the stress ratio, the contact height ratio, and the weight ratio were confirmed for each spring index D / W.

  As shown in FIGS. 7 to 9, the result of the base being rectangular is that the stress ratio, the contact height, and the weight ratio are all significantly higher than the result of the base being a circle, whereas the base is the semicircular inner diameter side ( The cross-sectional shape in FIG. 5) and the results of the spring strands on the semicircular outer diameter side (cross-sectional shape in FIG. 6) were confirmed to be lower than the stress, contact height, and weight when the base was a circle. .

  In FIG. 10, the stress ratio is confirmed with the spring constant and the contact height being constant for the spring element wire whose base is the semicircular outer diameter side (cross-sectional shape in FIG. 6). In FIG. For the spring element wire on the radial side (cross-sectional shape in FIG. 6), the contact height ratio was confirmed with a constant spring constant and stress. In both FIG. 10 and FIG. 11, the stress and the contact height when the flatness ratio T / W = 0.76 was set to 1, and the flatness ratio T / W was changed.

  As shown in FIGS. 10 and 11, the same change tendency of the stress and the contact height could be obtained as the flatness ratio decreased in any spring index D / W.

[Α and stress ratio]
FIG. 12 is a graph showing changes in the stress ratio when the value of α is changed. FIG. 12 relates to a spring element having a base with a semicircular outer diameter side (cross-sectional shape in FIG. 6) and a flatness ratio T / W = 0.76, and the spring constant, coil outer diameter, and contact height are constant. . FIG. 12 also shows, as a comparative example, a stress ratio of two examples with a circular base and flattening ratios T / W = 0.76 and 0.92 and a rectangular base with flattening ratios T / W = 0.76. It shows.

  Here, when the stress ratio of the base is circular and the flatness ratio T / W = 0.92 is set to 1, and a range in which the stress ratio is less than 1 is specified, α = 1.85 to 2.45 from FIG. . When α is in the range of 1.85 to 2.45, it is advantageous in terms of design with respect to the comparative example in which the base is circular and the flatness ratio T / W = 0.92.

  Furthermore, since the stress ratio is advantageous as compared with the case of an ellipse with α = 2, the value of α can be specified in the range of α = 2.1 to 2.4.

[Effect of Example 1]
In the first embodiment of the present invention, the coil outer diameter side portion 7 has a semicircular shape represented by x ² + y ² = b ² with respect to the outer peripheral shape of the cross section of the spring wire 3 wound in a coil shape. (X / a) ^α + (y / b) ^α is a non-circular shape having a major axis = a and a minor axis = b represented by ^α = 1, and the value of α is α = 1.85 to 2.45. The coil spring 1 is a flat plane 9 and 11 in which a coil portion adjacent in the direction of the coil axis 4 can abut between the inner and outer diameter side portions 5 and 7 of the outer peripheral cross section of the spring wire 3. Are provided in a semicircular shape and a non-circular shape so that the flat surfaces 9 and 11 can stably receive a load in a close contact state, reduce the flattening rate T / W, shorten the contact length, and have a cross-sectional shape. The continuity of stress distribution in the circumferential direction can improve the uniformity of stress distribution. That.

  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.

  Since the flat surfaces 9 and 11 are provided on both sides of the spring wire 3 in the cross-sectional shape of the coil axis 4, the load in the direction of the coil axis 4 in the coil contact state can be reliably received, and the displacement in the coil radial direction is prevented. It can be surely suppressed.

  Since the flat surfaces 9 and 11 are inclined with respect to each other so that the cross-sectional shape of the spring wire is wedge-shaped, the load in the direction of the coil axis 4 is reliably ensured even when the coil axis 4 is arcuate. It can be received, and deviation in the coil radial direction can be reliably suppressed.

  Since the coil axis of the spring element wire 3 is in a free state and the coil axis is an arc shape, it is easy to assemble the coil axis 4 into an arc shape and easily according to the arc shape of the flat plane 9 and 11 coil axis 4 Can be set to

  The coil shape of the spring wire 3 can also be set to a shape having the radius of curvature R of the coil axis 4 in the assembled state. In this case, a degree of freedom in design according to the curvature of the coil axis 4 of the flat surfaces 9 and 11 can be ensured.

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.
[Others]
The forming contact surface is not limited to the flat surfaces 9 and 11, and can be formed with some convex surface or concave surface. Further, the forming contact surface can be formed such that one side of the spring element wire 3 in the direction of the coil axis 4 is slightly convex, and the other side is slightly concave.

DESCRIPTION OF SYMBOLS 1 Coil spring 3 Spring element wire 4 Coil axis 5 Coil inner diameter side part 7 Coil outer diameter side part 9, 11 Flat surface (molding contact surface)

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 is a semicircular shape represented by x ² + y ² = b ² ,
A coil spring in which a coil inner diameter side portion is a non-circular shape having a major axis = a and a minor axis = b represented by (x / a) ^α + (y / b) ^α = 1,
Between the semi-circular shape and the non-circular shape, provided between the coil inner and outer diameter side portions of the outer peripheral cross-section of the spring element wire, a forming contact surface capable of contacting a coil portion adjacent in the coil axial direction,
T: Maximum dimension in the coil axial direction between the forming contact surfaces W: Maximum dimension in the coil radial direction of the spring element wire,
A coil spring in which a flat surface having a flatness ratio of 0.92 is formed on a spring wire having a circular cross section with a stress ratio at a constant spring constant and a constant contact height and a contact height ratio at a constant spring constant and a constant stress. In order to lower the comparison, the flatness is 0.6 ≦ T / W ≦ 0.76, and the value of α is in the range of α = 1.85 to 2.45,
The stress of the coil inner diameter side portion was continuously dispersed to the molding contact surface,
A coil spring characterized by that. The coil spring according to claim 1,
The value of α was specified in a range of α = 2.1 to 2.4.
A coil spring characterized by that. The coil spring according to claim 1 or 2,
The molding contact surfaces are provided on both sides in the coil axis direction of the cross-sectional shape of the spring element wire,
A coil spring characterized by that. The coil spring according to claim 3,
The two molding contact surfaces are formed to be inclined with respect to each other so that the cross-sectional shape of the spring wire becomes a wedge shape,
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, and the coil axis is an arc shape.
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 attenuator) of a friction disk for a dual mass flywheel or a lock-up for a torque converter or a wet or dry clutch mechanism.