JP2002168278A - Coil spring, coil spring assembly, and damper mechanism provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil spring capable of securing durability and simplifying strength improvement processing in the coil having no seated portion to be ground. SOLUTION: Shot blasting is applied to a certain limited part of the coil spring 41 having no seated portion to be ground on both ends. This shot blasting is applied to the portion with at least 6/8 turns to 7/8 turns from each end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil spring, and more particularly to a coil spring without end-turn grinding.

[0002]

2. Description of the Related Art In a clutch of a vehicle or the like, a damper mechanism is incorporated in a clutch disk assembly to attenuate and absorb a torque fluctuation when transmitting torque from an engine to a transmission. For this damper mechanism, a coil spring is often used.

[0003] The damper mechanism mainly includes an input rotary member that can be connected to an input flywheel on the engine side, an output rotary member that is connected to a shaft extending from the transmission, and an input rotary member and an output rotary member that are elastically rotated in the rotational direction. And a coil spring that is connected to each other. When the input rotary member and the output rotary member rotate relative to each other, the coil spring is compressed in the rotation direction between the two members.

[0004] Usually, the coil spring used in such a clutch disk assembly is used in a state where an end turn is ground and a flat end surface is provided.

[0005]

However, by performing end-to-end grinding, the ground portion is likely to be chipped,
Since the coil spring may rotate and cause a problem due to the exchange of the outer peripheral portion and the inner peripheral portion, the applicant of the present application uses the damper mechanism of the clutch disk assembly to mount the coil spring without end-turn grinding. The invention was adopted, and a patent application (Japanese Patent Application No. 11-3319)
No. 98).

[0006] On the other hand, the coil spring without the end-turn grinding is also used at the portion where the compressive force is repeatedly applied in the clutch as described above, and therefore, the stress is applied repeatedly as in a normal spring. Therefore, in order to secure the durability of the coil spring, it is necessary to perform a fatigue strength improving process such as shot peening which is generally performed on the coil spring.

However, processing such as shot peening requires time and cost. Therefore, if possible, it is desired not to perform the strength improving process, but in many cases, the durability cannot be secured.

[0008] An object of the present invention is to provide a coil spring without end-winding grinding, in which durability is ensured and strength improvement processing is simplified.

[0009]

According to a first aspect of the present invention, there is provided a coil spring having no end-turn grinding, wherein a limited portion is subjected to a strength improving process.
This strength improvement processing is performed on at least a portion of (6/8) winding to (7/8) winding from the end.

The inventor of the present application paid attention to the fact that a part to be damaged is specified to some extent by repeating a durability test of a coil spring without end winding grinding. Specifically, the inventors have noticed that the probability of occurrence of breakage increases in the vicinity of a portion which is returned (ほ ど) from the end of the coil spring.

Further, the inventor of the present application has observed the fracture surface of the broken part and has noticed that the fracture is caused mainly by bending stress and torsion stress is applied thereto. Then, the inventor of the present application measured bending stress at several points near the end of the coil spring without end-winding grinding, and found that the number of turns from the end was (6/8) to (7/8). It has been found that the bending stress has a peak.

In view of this, in the coil spring of the first aspect, at least (6/8) winding to (7/8) from the end.
Durability is improved by performing strength improvement processing on a limited portion including the winding portion. As described above, since the strength of the (6/8) to (7/8) turns from the end, which is the weakest portion, is improved, the durability of the coil spring increases. In addition, since the strength improvement processing is not performed on the entire coil spring as in the related art, but the processing is performed only on a limited portion including the weakest part, the processing time is shortened and the cost is reduced. That is, here, the strength improvement processing can be simplified while ensuring the durability of the coil spring.

According to a second aspect of the present invention, there is provided the coil spring according to the first aspect, wherein the strength improving treatment is performed at least from (5/8) winding to (8/8) from the end.
It is applied to the winding part.

Here, the inventor of the present invention measured bending stress at several points near the end of the coil spring without end-winding grinding, and found that the number of turns from the end was (6/8) to (7 /
8), the bending stress peaks, and the number of turns from the end is (5/8) to (6 /
8) and (7/8) to (8/8) that relatively high bending stress was generated.

In view of this, in the coil spring according to the second aspect, in order to further increase the durability, at least the (5/8) winding to (8/8) winding from the end, which is the weak portion, has at least strength. Improvement processing is performed.

According to a third aspect of the present invention, there is provided the coil spring according to the first or second aspect, wherein the strength improving process is a process for mainly improving fatigue strength. The coil spring according to a fourth aspect is the coil spring according to the third aspect, wherein the strength improvement processing is processing for causing a shot to collide with a metal surface at high speed.

Here, the fatigue strength of a limited portion of the coil spring is improved by using a process such as shot peening in which a shot collides with a coil spring. In the case of such a process, if the process is performed on the entire coil spring, the amount of energy supplied by the shot per unit area tends to be small. However, in this case, the shot only has to collide with a limited portion. It becomes easy to strengthen the weak part. Also, the shot injection device does not need to be so large.

It is desirable that the material, shape, size, and injection speed of the shot be appropriately selected according to the material and size of the coil spring to be processed. Claim 5
Is a coil spring assembly used for a damper mechanism of a clutch,
A coil spring according to any one of claims 1 to 4, and a pair of spring seats. Each spring seat has a seating surface shaped to abut the entire end turn.

According to a sixth aspect of the present invention, there is provided a damper mechanism including an input rotary member, an output rotary member, and a coil spring assembly. The coil spring assembly according to the fifth aspect is configured to elastically connect the input rotary member and the output rotary member in a rotational direction.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <Outline of Clutch Disk Assembly 1> FIG. 1 is a sectional view of a clutch disk assembly 1 including a coil spring according to an embodiment of the present invention. FIG. 2 is a plan view of the clutch disk assembly 1. The clutch disc assembly 1 is a component for transmitting power used in a clutch device of a vehicle, and has a clutch function and a damper mechanism. The clutch function is a function of transmitting and interrupting torque by connecting and disconnecting to and from a flywheel (not shown). The damper function is a function of absorbing and attenuating a torque fluctuation or the like input from the flywheel side by a coil spring or the like.

In FIG. 1, OO is the rotating shaft of the clutch disk assembly 1. An engine and a flywheel (not shown) are arranged on the left side of FIG. 1, and a transmission (not shown) is arranged on the right side of FIG. Further, the arrow R1 side in FIG. 2 is the drive side (rotation direction positive side) of the clutch disk assembly 1, and the arrow R2 side is the opposite side (rotation direction negative side). In the following description, the “rotational (circumferential) direction”, “axial direction”, and “radial direction” refer to the respective directions of the clutch disk assembly 1 as a damper mechanism, unless otherwise specified.

<Structure of Clutch Disk Assembly 1> The clutch disk assembly 1 mainly includes an input rotating unit 2 and
It comprises an output rotating section 3 and an elastic connecting section 4 arranged between the input rotating section 2 and the output rotating section 3.

[Structure of Input Rotating Section 2] Torque is input to the input rotating section 2 from a flywheel. The input rotating unit 2 mainly includes a clutch disk 11, a clutch plate 12, and a retaining plate 13.

The clutch disc 11 is a part which is pressed and connected to the flywheel. The clutch disk 11 has a cushioning plate 15 and a pair of friction facings 16 and 17 fixed on both surfaces thereof. The clutch plate 12 and the retaining plate 13 are disk-shaped annular members, and are arranged at predetermined intervals in the axial direction.

The clutch plate 12 is arranged on the engine side, and the retaining plate 13 is arranged on the transmission side. On the outer periphery of the retaining plate 13,
A cylindrical wall 22 extending toward the clutch plate 12 is formed. Further, a plurality of fixing portions 23 extend radially inward from the tip of the wall 22. The fixing portion 23 is arranged on the transmission side surface of the clutch plate 12 and is fixed to the clutch plate 12 by a plurality of rivets 20. As a result, the clutch plate 12 and the retaining plate 13 rotate integrally, and the axial distance is maintained. In addition, rivets 20
The inner peripheral part of the cushioning plate 15
In addition, it also plays a role of fixing to the outer peripheral portion of the clutch plate 12.

Each of the clutch plate 12 and the retaining plate 13 has a center hole. A hub 7 described later is arranged in the center hole. In addition, the clutch plate 12 and the retaining plate 13 include:
A plurality of windows 68 arranged in the circumferential direction are respectively formed. Since both windows 68 have the same structure, here,
The window 68 of the retaining plate 13 will be described. The window 68 is constituted by a hole penetrating in the axial direction and a spring support formed along the edge of the hole. The spring support portion includes an outer peripheral side support portion 69a and an inner peripheral side support portion 69a.
b, and rotation direction support portions 69c and 69d (the rotation direction support portion 69c is on the R1 side, and the rotation direction support portion 69d is on the R2 side). Outer side support part 69a
Is curved in a shape substantially along the circumferential direction, and the inner peripheral side support portion 69b extends substantially linearly. The rotation direction support portions 69c and 69d extend substantially linearly in the radial direction, but are not parallel to a straight line passing through the center of the window portion 68 in the circumferential direction and the center O of the clutch disc assembly 1, and The inner side in the direction is inclined so that the inner side in the rotational direction is located closer to the inner side in the rotational direction than the outer side in the radial direction (the center side in the circumferential direction of the window 68). For this reason, the rotation direction support 69c and the rotation direction support 69d are not parallel to each other. The outer peripheral side support portion 69a and the inner peripheral side support portion 69b are cut-and-raised portions, and the rotational direction support portions 69c and 69d are composed of cut-and-raised portions on both sides in the radial direction and a radially intermediate plate cross-sectional portion.

[Configuration of Output Rotating Unit 3]
It comprises a hub 7, a hub flange 6, and a low-rigidity damper 8.

The hub 7 is a cylindrical member disposed in the center holes of the clutch plate 12 and the retaining plate 13. The hub 7 is spline-engaged with a transmission input shaft (not shown) inserted into its center hole.

Further, a hub flange 6 is arranged on the outer periphery of the hub 7. That is, the hub flange 6 is disposed between the clutch plate 12 and the retaining plate 13 in the axial direction. The inner peripheral portion of the hub flange 6
It is connected to the hub 7 by a low rigidity damper 8. Therefore, when the hub flange 6 and the hub 7 rotate relative to each other, the small coil spring provided on the low-rigidity damper 8 is compressed in the rotation direction. Furthermore, hub flange 6
Is arranged radially inward of the wall 22 of the retaining plate 13. That is, the outer periphery of the hub flange 6 is covered by the wall 22.

Further, window holes 31 are formed in the hub flange 6 so as to correspond to the window portions 68 of the clutch plate 12 and the retaining plate 13. The window holes 31 are arranged at equal intervals in the circumferential direction. The window hole 31 is a hole formed to penetrate in the axial direction, and generally corresponds to the shape of the window portion 68. The window hole 31 extends long in the circumferential direction.
As shown in the figure, the outer peripheral side support portion 35 and the inner peripheral side support portion 32
And rotation direction support portions 33 and 34. The rotation direction support part 33 is disposed on the R1 side, and the rotation direction support part 34 is
It is arranged on two sides. The outer peripheral side support portion 35 has a curved shape along the circumferential direction. The inner peripheral side support portion 32 extends substantially linearly. The rotation direction support portion 33 and the rotation direction support portion 34 extend substantially linearly in the radial direction. More specifically, the rotation direction support portion 33 and the rotation direction support portion 34
Is not parallel to a straight line connecting the center of the window hole 31 in the rotational direction and the center O of the clutch disc assembly 1, but is inclined so that the radially inner side is located closer to the rotational direction inside the window hole 31 than the radially outer side. ing.

[Structure of the elastic connecting part 4]
It comprises a plurality of coil spring assemblies 9.
Each coil spring assembly 9 includes a window hole 31 and a window portion 68.
Is located within. As shown in FIG. 3, the coil spring assembly 9 includes a coil spring 41 and a pair of spring seats 72 and 73 provided at both ends thereof.

The coil spring 41 has a closed end at both ends to form an end winding. However, the end face of the end winding is not ground, and maintains the cross-sectional shape of the spring material. Here, the end winding is a portion corresponding to one winding at both ends of the coil spring 41. The fatigue strength improvement processing (shot peening) for the end winding will be described later in detail.

Referring to FIG. 4 to FIG.
2, 73 will be described. Spring seat 7
Each of the seat portions 74 has a seat surface 75 for receiving an end turn of the coil spring 41. Seat part 7
The other side of 4 is a back surface 78 for being supported by the window hole 31 and the window portion 68. As is clear from FIG. 3, the bearing surface 75 is circular. The seat surface 75 has a substantially flat first semicircle 7.
5a, and a second semicircle 75b that is inclined so that the surface gradually increases from one end to the other end of the first semicircle 75a. One end of the second semicircle 75b is formed continuously from the first semicircle 75a. The other end of the second semicircle 75b is
A step is formed with the first semicircle 75a. In this step portion, a contact surface 75c that faces in the circumferential direction is formed. The shape of the seat surface 75 is the same as that of the coil spring 4.
The shape corresponds to the end winding of No. 1, and the leading end surface of the end winding comes into contact with the contact surface 75c.

The seat portion 74 is formed with a protruding portion 80 extending inward in the circumferential direction of the window hole 31. The protrusion 80 has a substantially columnar shape. Tip surface 8 of protrusion 80
Although 1 extends straight along the axial direction, its radially outer portion is inclined so as to be located on the rotation direction outer side of the window hole 31 as compared with the radially inner portion in plan view.

Back surface 78 of spring seats 72, 73
Are in contact with and supported by the rotation direction support portions 69c and 69d of the window portion 68. In this state, the spring seat 7
2, 73 can be separated from the rotation direction support parts 69c, 69d in the rotation direction (toward the opposite circumferential end). However, when the spring seats 72 and 73 are engaged with the coil spring 41, they cannot move in the axial direction and the radial direction. Further, the spring seat 72,
73 is a central axis PP of the coil spring 41 with respect to the clutch plate 12 and the retaining plate 13.
Are locked so that they cannot rotate around the center. This is because the rotation direction support portions 69c, 6 that receive the spring seats 72, 73
9d are not parallel to each other but inclined in plan view.

As shown in FIG. 3, the spring seats 72 and 73 are supported by the rotation direction support portions 33 and 34 of the window hole 31. Specifically, the back surface 78 is in contact with the rotation direction support portion 33 and the rotation direction support portion 34. In this state, the spring seats 72, 73 can be separated from the rotation direction support portions 33, 34 in the rotation direction (toward the opposite circumferential end). However, the spring seats 72 and 73 cannot move in the axial direction and the radial direction in the engaged state. In the state shown in FIG. 3, the spring seats 72 and 73 hold the center axis P of the coil spring 41 against the hub flange 6.
Locked so that it cannot rotate around -P. This is because the rotation direction support parts 33 and 34 which receive the spring seats 72 and 73 are provided.
However, they are not parallel to each other but inclined in plan view.

The end turn of the coil spring 41 is carried out on the seat surface 75 of the seat portion 74 (first semicircle 75a, second semicircle 75b).
Is in full contact with Further, the tip cross section of the coil spring 41 is in contact with the contact surface 75c.
Therefore, the coil spring 41 cannot rotate around its own central axis PP with respect to the pair of spring seats 72, 73. That is, in the pair of spring seats 72 and 73, since the contact surface 75c faces the opposite side in the winding direction of the coil spring 41, the coil spring 41 cannot rotate to either side around the central axis PP. In this state, in the coil spring 41, the number of turns on the inner peripheral side is five, and the number of turns on the outer peripheral side is four (excluding end turns). That is, the number of turns on the inner peripheral side is larger by one turn than the number of turns on the outer peripheral side. The coil spring 41 does not rotate around the spring center axis PP with respect to the spring seats 72, 73, and the spring seats 72, 73 further rotate around the spring center axis PP with respect to the plates 12, 13, etc. Since it does not rotate, that state is maintained. That is, the number of turns on the inner peripheral side of the coil spring 41 is always larger than the number of turns on the outer peripheral side.

<Motion of Coil Spring 41 in Operation of Clutch Disk Assembly 1> Next, the operation will be described. From the free state in FIG. 3, the plates 12, 13 are twisted toward the R1 side with respect to the hub flange 6. Then, the coil spring 41 is compressed in the rotation direction between the rotation direction support portion 33 of the window hole 31 and the rotation direction support portion 69d of the window portion 68. At this time, in the coil spring 41, the deflection amount of the outer peripheral side portion is larger than the deflection amount of the inner peripheral side portion, but the number of turns of the inner peripheral side portion is larger than the number of turns of the outer peripheral side portion. The difference in the amount is small.

<Shot Peening for End Winding of Coil Spring 41> A part corresponding to one turn at both ends of the coil spring 41, that is, for an end winding,
For the purpose of improving the fatigue strength, a process called shot kneading is performed. This will be described with reference to FIG.

FIG. 9A shows the structure of the end of the coil spring 41. The end turn 51 at the end of the coil spring 41 is not ground. For this reason, the circumferential end face 52 of the coil spring 41 has the same wire shape as the coil and is not flat. In addition, the end winding 51
Is also equal to an arbitrary cross section of the coil element wire.

In the present embodiment, such an end winding 51 of the coil spring 41 is subjected to shot peening called WPC processing. In this process, an extremely small shot (such as small steel particles) is jetted at high speed toward a part of the end winding 51 by an air gun or the like, thereby improving the fatigue strength of the portion to be processed.

In this case, the coil spring 41
Rather than performing shot peening on the entirety, processing is performed on only a part of the coil spring 41. Specifically, as shown in FIG. 9B, processing is performed on a limited portion including a portion of (5/8) winding to (8/8) winding from the end.

The determination of the limited portion where this processing is performed is based on the result of the durability test of the coil spring without the end-turn polishing (grinding) and the result of the bending stress measurement on each end-turn portion of the coil spring. The inventor of the present application who observed and analyzed the damaged portion of the coil spring that was damaged by the durability test showed that many damages were found in the end winding portion, that the bending stress was mainly, and that the damage occurred due to the application of torsional stress Also noticed. Then, bending stress was measured at several points near the end of the coil spring, and a measurement result as shown in FIG. 10 was obtained.
The bending stress reaches a peak at a portion where the number of turns from the end is (6/8) to (7/8), and the number of turns from the end is (5/8).
/ 8) to (8/8), it has been found that bending stress is generated such that the safety factor has no margin in terms of fatigue strength.

Based on this, in the present embodiment, shot peening is performed in such a manner that the shot hits at least the portion where the number of turns from the end is (5/8) to (8/8). . Thereby, the fatigue strength of the weak portion where the number of turns from the end including the weakest portion of (6/8) to (7/8) winding from the end is (5/8) to (8/8) is reduced. This improves the durability of the coil spring 41.

In addition, instead of performing strength improvement processing on the entire coil spring as in the related art, shot peening is performed only on a limited portion including a weak portion, so that the processing time is shortened and the cost is reduced. That is, here, expensive processing such as shot peening can be simplified while ensuring the durability of the coil spring 41. Further, when the entire coil spring is subjected to the processing, the amount of energy supplied by the shot per unit area tends to be small, but here, the shot only needs to collide with a limited portion, and the weak portion is effectively strengthened. In addition to this, a small-sized shot injection device can be used.

[0046]

According to the present invention, at least (6 /
8) The strength improvement processing is performed on the limited portion including the winding to (7/8) winding portion, and (6 /
8) Since the strength of the wound to (7/8) wound portion is at least improved, the durability of the coil spring is increased. In addition, since the strength improvement processing is not performed on the entire coil spring as in the related art, but the processing is performed only on a limited portion including the weakest part, the processing time is shortened and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a clutch disk assembly including a coil spring according to an embodiment of the present invention.

FIG. 2 is a partial perspective plan view of a clutch disk assembly.

FIG. 3 is an enlarged plan view near a coil spring.

FIG. 4 is a front view of a spring seat.

FIG. 5 is a view taken in the direction of the arrow V in FIG. 4;

6 is a view taken in the direction of arrow VI in FIG. 4;

FIG. 7 is a view taken in the direction of arrow VII in FIG. 4;

FIG. 8 is a view taken in the direction of arrow VIII in FIG. 4;

FIG. 9 is a detailed view of an end of a coil spring.

FIG. 10 is a view showing a measurement result of a bending stress of a coil spring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clutch disk assembly 2 Input rotary part (input rotary member) 3 Output rotary part (output rotary member) 4 Elastic connection part 9 Coil spring assembly 41 Coil spring 51 End turn 72, 73 Spring seat 75 Seat surface

Claims (6)

[Claims] Claims: 1. A coil spring without end-winding grinding, in which a limited portion is subjected to a strength improving treatment, and at least a (6/8) to (7/8) winding portion from an end. A coil spring having been subjected to the strength improving treatment. (2) At least (5/8) winding to (8) from the end
/ 8) The coil spring according to claim 1, wherein the strength improving process is applied to a wound portion. 3. The coil spring according to claim 1, wherein the strength improving process is a process for mainly improving fatigue strength. 4. The coil spring according to claim 3, wherein the strength improving process is a process of causing a shot to collide with a metal surface at a high speed. 5. A coil spring assembly used for a damper mechanism of a clutch, comprising: the coil spring according to claim 1; and a seating surface having a shape abutting on the entire end winding. 1
A coil spring assembly comprising: a pair of spring seats. 6. A damper comprising: an input rotary member; an output rotary member; and the coil spring assembly according to claim 5, which elastically connects the input rotary member and the output rotary member in a rotational direction. mechanism.