JP2004084876A - Clutch spring for spring clutch and spring clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring clutch capable of satisfactorily lubricating the contact part between a clutch spring and a clutch surface. <P>SOLUTION: A clutch spring 11 having coil parts 11a the side surfaces of which are in contact with each other is integrated between a pulley 1 and a pulley hub 2 integrated to the inside thereof, a cylindrical surface 13a on the circumference of the clutch spring 11 is elastically brought into contact with the cylindrical clutch surface 14 provided on the inside of the pulley 1, and one end part of the clutch spring 11 is connected to the pulley hub 2. Both side surfaces of the coil parts 11a of the clutch spring 11 are formed in protruding circular surfaces 12, so that grease in a grease sealing space 10 provided on the inner side of the clutch spring 11 can smoothly flow between the coil parts 11a by the centrifugal force in rotation, whereby the lubricating property of the contact part between the clutch spring 11 and the clutch surface 14 is improved. <P>COPYRIGHT: (C)2004,JPO

Description

【００３９】
ここで、　Ｔ_Ｌ：ロックトルク（Ｎ−ｍｍ）
Ｔ_Ｓ：空転起動トルク（Ｎ−ｍｍ）
Ｔ：負荷トルク（Ｎ−ｍｍ）
Ｅ：ばねの縦弾性係数（Ｎ−ｍｍ^２）
Ｉ_Ａ：ばねの軸方向まわりの断面２次モーメント（ｍｍ^４）
Ｄ_Ａ：軸・プーリの径（ｍｍ）
Ｄ_Ｓ：ばねの内径
δ：しめしろ〔直径分〕（ｍｍ）
μ：摩擦係数
Ｎ：ばねの有効巻数
ｂ：ばねの板幅〔軸方向〕（ｍｍ）
ｈ：ばねの板厚〔径方向〕（ｍｍ）
Ａ：ばねの断面積〔ｂ×ｈ〕（ｍｍ^２）
σ：ばねの応力（Ｎ／ｍｍ^２）
【００４０】
但し、上式において、
（１）Ｔ_Ｌ（ロックトルク）は、スプリングクラッチでロック方向にトルクが負荷された際にロックを保持できる最大トルク値を示し、それ以上のトルクが負荷されるとばねが滑り出す。
（２）Ｔ_Ｓ（空転起動トルク）は、スプリングクラッチに空転方向にトルクが負荷された際に空転を開始するトルク値を示し（ばねが滑り出すトルク）、Ｔ_Ｓで算出された値以下のトルクを負荷してもクラッチは空転しない。
（３）σ（ばね応力）は、スプリングクラッチに負荷トルクが作用した時に線材に発生する内部応力であり、この値が線材の許容引張り応力を上回ると線材が破断する。従って、線材の許容引張り応力の（３）式を変形した（３’）式によれば、線材の許容最大トルクを逆算することができる。
【００４１】
又、上式は外装式のクラッチばねに適用される理論式であるため、上記実施形態の内装式のクラッチばねに適用するためには、以下のような数式の置換えをする必要がある。即ち、
δ＝Ｄ_Ａ’　−Ｄ_Ｓ’
Ｄ_Ａ’　：軸、プーリの内径
Ｄ_Ｓ’　：ばねの外径
【００４２】
以上の置換えをすることにより理論式を適用して決定した断面寸法を有するクラッチばね１１に対し、ロックトルクＴ_Ｌや空転トルクＴ_Ｓの値を実験により確認したところ理論式にほぼ合致することが確かめられた。従って、上記理論式を用いて実施形態のクラッチばね１１の断面形状を上述した例以外の形状に適用し、潤滑性に優れたスプリングクラッチを得ることができる。
【００４３】
【発明の効果】
以上のように、この発明においては、コイル部の側面を凸円状の円弧面としたことによって、クラッチばねの内側に保持されたグリースを回転時の遠心力によってコイル部の接触面間よりクラッチばねの外径側にスムーズに流動させることができると共に、コイル部の円弧面の外径部間に多くのグリースを保持させることができる。このため、クラッチばねとクラッチ面の接触部をグリースによって効果的に潤滑することができ、潤滑性に優れた長寿命のスプリングクラッチを得ることができる。
【図面の簡単な説明】
【図１】この発明に係るスプリングクラッチの実施の形態を示す縦断正面図
【図２】図１のＩＩ−ＩＩ線に沿った断面図
【図３】図１のクラッチばね部を拡大して示す断面図
【図４】（Ｉ）は２面押し品から成る角線材の断面図、（ＩＩ）は４面押し品から成る角線材の断面図
【図５】従来のスプリングクラッチを示す縦断正面図
【符号の説明】
１　プーリ（入力側部材）
２　プーリハブ（出力側部材）
１１　クラッチばね
１１ａ　コイル部
１２　円弧面
１３ａ、１３ｂ　円筒面
１４　クラッチ面[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch spring and a spring clutch for transmitting and interrupting a rotational torque between an input member and an output member.
[0002]
[Prior art]
Generally, in an automobile engine, driving energy is generated during an explosion stroke, and thus the angular speed of the crankshaft changes during one revolution. When such a rotation of the crankshaft is driven by a belt transmission to an engine accessory having a large inertial force, such as an alternator, the rotation speed of the rotation shaft of the engine accessory increases when the angular speed of the crankshaft decreases. Slip occurs between the pulley and the belt attached to the shaft.
[0003]
Further, when the engine is rapidly decelerated from the high-speed rotation state, the engine accessory such as the alternator tries to continue the high-speed rotation by the inertia force, so that a slip occurs between the pulley and the belt in the same manner as described above, and at the time of the slip, Abnormal noise is generated, or the belt is worn and durability is reduced.
[0004]
To solve such inconvenience, a clutch pulley device incorporating a spring clutch has been proposed. FIG. 5 shows a clutch pulley device employing a spring clutch. In this clutch pulley device, a pulley hub 22 attached to a rotation shaft of an engine accessory is provided inside a pulley 21 to which rotation of a crankshaft is transmitted via a belt, and the pulley 21 and the pulley hub 22 are relatively moved by a bearing 23. It is rotatably supported.
[0005]
Further, an annular inwardly projecting portion 24 is provided on the inner periphery of the pulley 21, while an annular outwardly projecting portion 25 is formed on the outer periphery of the pulley hub 22 so as to face the inwardly projecting portion 24 in the axial direction. A spring storage space 26 extending in the axial direction astride both the protrusions 24 and 25 is provided on a surface facing the outward protrusion 25 and the inward protrusion 24, and a spring clutch 30 is provided in the spring storage space 26. Incorporated.
[0006]
The spring clutch 30 is provided with two cylindrical clutch surfaces 31a and 31b arranged in the axial direction on the inner surface of the outer peripheral wall of the spring storage space 26, and the spring storage space 26 straddles the cylindrical clutch surfaces 31a and 31b. The clutch spring 32 of a predetermined length is incorporated, and the cylindrical outer surface of the clutch spring 32 is brought into elastic contact with each of the clutch surfaces 31a and 31b.
[0007]
In the clutch pulley device, when the pulley 21 rotates in one direction by contact with the belt, the diameter of the clutch spring 32 is increased to increase the engagement force on the clutch surfaces 31a and 31b. Is transmitted to the pulley hub 22.
[0008]
When the rotation speed of the pulley hub 22 exceeds the rotation speed of the pulley 21, the clutch spring 32 is reduced in diameter to weaken the engaging force on the clutch surfaces 31a and 31b, and the contact portion between the clutch spring 32 and the clutch surfaces 31a and 31b is reduced. To prevent the transmission of the rotation from the pulley hub 22 to the pulley 21 side, thereby preventing the slip from occurring between the pulley 21 and the belt.
[0009]
Here, in the spring clutch 30 incorporated in the clutch pulley device, if the clutch spring 32 is formed of a round wire, the contact of the clutch spring 32 with the clutch surfaces 31a and 31b becomes line contact, and the frictional engagement force is weak. Slippage occurs between the clutch surfaces 31a and 31b, thereby deteriorating the responsiveness of the clutch and causing loss in torque transmission. Further, if there is a gap between the coil portions 32a of the clutch spring 32, the clutch spring 32 having a long length is required to obtain an appropriate frictional engagement force, and the axial length of the clutch pulley device is increased. Problems arise.
[0010]
Therefore, in the spring clutch 30, the clutch spring 32 is formed of a square wire to increase the contact area with the clutch surfaces 31a and 31b, thereby increasing the frictional engagement force. In addition, the side surfaces of the coil portion 32a are brought into contact with each other to reduce the axial length of the clutch spring 32.
[0011]
In the clutch pulley device as described above, grease is filled in the spring storage space 26 between the inner diameter surface of the clutch spring 32 and the outer diameter surface of the pulley hub 22, and the grease contacts the clutch spring 32 with the clutch surfaces 31a, 31b. The parts are lubricated.
[0012]
[Problems to be solved by the invention]
In the clutch pulley device shown in FIG. 5, since the side surfaces of the coil portion 32a of the clutch spring 32 are in surface contact, the inner side of the grease clutch spring 32 which tends to move outward due to centrifugal force during rotation. The fluidity from the outside to the outer diameter side is poor, so that the contact portions between the clutch spring 32 and the clutch surfaces 31a and 31b cannot be effectively lubricated, and there are still points to be improved in improving the lubricity. I have.
[0013]
Further, the outer peripheral edge of the side surface of the coil portion 32a of the clutch spring 32 is chamfered. However, since the space formed between the chamfers is small, a large amount of grease cannot be held, and the holding amount is reduced. There are still points to be improved in increasing the number.
[0014]
An object of the present invention is to provide a clutch spring and a spring clutch for a spring clutch, which can lubricate a contact portion with a clutch surface in a satisfactory manner.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in a clutch spring for a spring clutch according to the present invention, a wire rod is wound in a helical shape so that side surfaces of an axially continuous coil portion are in contact with each other, and an outer periphery and an inner periphery are formed. In a clutch spring for a spring clutch having a cylindrical surface, at least one side surface of each of the coil portions is configured to have a convex circular arc surface.
[0016]
As described above, since the side surface of the coil portion is formed into a convex circular arc surface, the side surface of the coil portion can be brought into line contact, so that the grease held inside the clutch spring is rotated by centrifugal force during rotation. The fluid can easily flow to the outer diameter side from between the side surfaces of the coil portion, and the contact portion between the cylindrical surface on the outer periphery of the clutch spring and the clutch surface where the cylindrical surface is elastically contacted can be effectively lubricated.
[0017]
In addition, since the side surface of the coil portion is an arc surface, a large space can be formed on the outer diameter side between the side surfaces facing each other in the axial direction, and a large amount of grease can be held in the space.
[0018]
In this case, by adopting a two-sided pushing square wire that is pressed against two surfaces when a round wire is pulled out, a clutch spring with low cost can be obtained as a wire forming the clutch spring.
[0019]
In the spring clutch according to the present invention, a cylindrical clutch surface is provided on the inner periphery of the input member, and the output member is rotatably supported by being incorporated inside the clutch surface and the input member. A clutch spring in which the side surfaces of the coil portions continuous in the axial direction are in contact with each other is incorporated, and the cylindrical surface on the outer periphery of the clutch spring is brought into elastic contact with the clutch surface, and when the input-side member rotates in one direction, In a spring clutch, a clutch spring is expanded in diameter by contact with a clutch surface and is brought into pressure contact with the clutch surface to transmit only one-way rotation of an input member to an output member via the clutch spring. A configuration is adopted in which the side surface of the coil portion in the clutch spring is a convex circular arc surface.
[0020]
According to the above configuration, the grease is filled in the grease-enclosed space formed between the inner peripheral surface of the clutch spring and the outer peripheral surface of the output side member, and the grease is applied to the clutch spring by centrifugal force during rotation. The fluid flows smoothly from between the side surfaces of the coil portion to the contact portion between the cylindrical surface on the outer periphery of the clutch spring and the clutch surface, and the contact portion is satisfactorily lubricated, so that the service life of the spring clutch can be extended.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 show a clutch pulley device employing a spring clutch according to the present invention. The clutch pulley device has a pulley 1 as an input-side member and a pulley hub 2 as an output-side member incorporated inside the pulley 1, and the pulley hub 2 has an output shaft 2a made of metal and an outer side. And a sleeve 2b provided.
[0022]
The sleeve 2b is made of a molded product of a sintered metal or a synthetic resin, and has flanges 3a and 3b formed at both ends on the outer periphery thereof, and a plurality of grease housing recesses 4 extending in the axial direction between the flanges 3a and 3b. They are formed at intervals in the direction.
[0023]
A detent mechanism 5 is provided between the output shaft 2a and the sleeve 2b. The anti-rotation mechanism 5 has a plurality of axially extending ridges 6 formed on the outer circumference of the output shaft 2a at intervals in the circumferential direction, and a plurality of anti-rotational ridges 6 formed on the inner circumference of the sleeve 2b. It is press-fitted into the groove 7.
[0024]
One end opening of an annular space formed between the inner periphery of the pulley 1 and the outer periphery of the pulley hub 2 is closed by a single-seal bearing 8 that supports the pulley 1 and the pulley hub 2 relatively rotatably. An opening at the other end of the annular space is closed by a seal member 9, and a grease sealed space 10 is formed between the seal member 9 and the single seal bearing 8.
[0025]
A clutch spring 11 is incorporated in the grease sealed space 10. The clutch spring 11 is made of a square wire formed by drawing a round wire.
[0026]
Here, there are a method of pressing four surfaces and a method of pressing two surfaces for pulling out a round wire material. In a normal spring clutch, a four-surface pressed product is adopted. Is formed by winding the rectangular wire in a helical shape so that the convex circular arc surfaces 12 on both sides of the coil portion 11a are in contact with each other, and the outer periphery and the inner periphery are cylindrical surfaces 13a and 13b. A spring 11 is formed.
[0027]
In the natural state, the outer diameter of the clutch spring 11 is larger than the inner diameter of the clutch surface 14 formed on the inner circumference of the pulley 1, and the clutch spring 11 is assembled into the grease enclosing space 10 in a reduced diameter, and The cylindrical surface 13a is in elastic contact with the clutch surface 14. One end of the clutch spring 11 is connected to a flange 3a located on the side of the single seal bearing 8 of the sleeve 2b.
[0028]
The clutch pulley device shown in the embodiment has the above-described structure. When driving an alternator as an engine accessory, a pulley hub 2 is attached to a rotating shaft of the alternator to prevent rotation, and a belt is wound around the outer periphery of the pulley 1 via a belt. Thus, the rotation of the crankshaft is transmitted to the pulley 1.
[0029]
When the rotation of the crankshaft is transmitted to the pulley 1 in the above use state, the diameter of the clutch spring 11 increases due to the contact with the clutch surface 14, and the press-engagement engagement force with respect to the clutch surface 14 increases. The rotation of the pulley 1 is transmitted to the pulley hub 2 via the clutch spring 11, and the rotation shaft of the alternator is rotated.
[0030]
When the rotation shaft of the alternator rotates, the moving speed of the belt decreases, and when the rotation speed of the pulley hub 2 that drives the rotation shaft of the alternator exceeds the rotation speed of the pulley 1, the clutch spring 11 contracts and the clutch spring 11 contracts with respect to the clutch surface 14. The press-contact engagement force is weakened, slippage occurs at the contact portion between the clutch spring 11 and the clutch surface 14, and the rotation of the pulley hub 2 is not transmitted to the pulley 1, so that the pulley 1 rotates freely.
[0031]
For this reason, slippage is prevented at the contact portion between the pulley 1 and the belt.
[0032]
Here, when the rotation is transmitted from the pulley 1 to the pulley hub 2 and the pulley 1 and the pulley hub 2 rotate, the grease filled in the grease enclosing space 10 tends to move in the outer diameter direction due to centrifugal force due to the rotation. At this time, since the side surfaces of the coil portions 11a of the clutch spring 11 that are in contact with each other are the convex circular arc surfaces 12, the grease moving in the outer diameter direction smoothly moves between the circular arc surfaces 12. Therefore, the contact portion between the cylindrical surface 13a on the outer periphery of the clutch spring 11 and the clutch surface 14 can be effectively lubricated.
[0033]
Further, by forming the side surfaces of the coil portions 11a of the clutch spring 11 that abut against each other as the arc surface 12, a relatively large gap 15 can be formed on the outer diameter side of the arc surface 12, and the gap 15 can be formed. Can hold a lot of grease. For this reason, the contact portion between the cylindrical surface 13a on the outer periphery of the clutch spring 11 and the clutch surface 14 can be more effectively lubricated, and a long-life spring clutch having excellent lubrication can be obtained.
[0034]
FIG. 4 (I) shows a cross-sectional shape of a square wire A of a two-sided pressed product forming the clutch spring 11, and FIG. 4 (II) shows a cross-sectional shape of a square wire B of a four-sided pressed product. By reducing the radius of curvature of the arc surfaces 12 on both sides of the square wire A of the two-sided pressed product, grease can flow smoothly from the inner diameter side to the outer diameter side, and more grease can be provided between the outer diameter portions of the arc surface 12. Can be obtained, but the contact area with the clutch surface 14 is reduced to the contrary, and the function of the clutch is reduced. Therefore, arcuate surface 14 has a height h ₁ of the arcuate surface 14 is preferably keep almost the same level to become such a radius of curvature and the height h ₀ of the chamfer C corners of four sides push products. By doing so, it is possible to improve the lubricity between the clutch spring 11 and the clutch surface 14 in a state where the contact area with the clutch surface 14 is secured.
[0035]
In the embodiment, the example in which the clutch spring 11 according to the present invention is applied to the clutch pulley device shown in FIG. 1 has been described, but the application example of the clutch spring 11 is not limited to this. For example, the present invention can be applied to a clutch pulley device shown in FIG.
[0036]
Further, in the embodiment, both side surfaces of the coil portion 11a are the arc surfaces 12, but only one side surface may be an arc surface. When the two side surfaces of the coil portion 11a are formed as the arc surfaces 12, a square wire made of a two-sided pressed product can be employed, so that the clutch spring 11 with low cost can be obtained.
[0037]
When determining the cross-sectional dimension of the clutch spring 11 used in the spring clutch of the above embodiment, it can be determined according to the following theoretical formula.
[0038]
(Equation 1)

[0039]
Here, T _L : lock torque (N-mm)
T _S : Idling start torque (N-mm)
T: Load torque (N-mm)
E: longitudinal elastic modulus of the spring (N-mm ² )
I _A : Second moment of area around the axial direction of the spring (mm ⁴ )
D _A : shaft / pulley diameter (mm)
D _S : inner diameter of spring δ: interference [for diameter] (mm)
μ: Coefficient of friction N: Effective number of turns of spring b: Plate width of spring [axial direction] (mm)
h: Spring thickness [radial direction] (mm)
A: Cross section of spring [b × h] (mm ² )
σ: stress of spring (N / mm ² )
[0040]
However, in the above equation,
(1) T _L (lock torque) indicates a maximum torque value at which lock can be maintained when torque is applied in the locking direction by the spring clutch. When a torque greater than that is applied, the spring starts to slide.
(2) T _S (idling start torque) indicates a torque value at which idling starts when torque is applied to the spring clutch in the idling direction (torque at which the spring starts to slip), and is equal to or less than the value calculated by T _S The clutch does not run idle.
(3) σ (spring stress) is an internal stress generated in the wire when a load torque acts on the spring clutch. If this value exceeds the allowable tensile stress of the wire, the wire breaks. Therefore, according to the equation (3 ′) obtained by modifying the equation (3) of the allowable tensile stress of the wire, the allowable maximum torque of the wire can be calculated backward.
[0041]
Further, since the above equation is a theoretical equation applied to an exterior clutch spring, it is necessary to replace the following equation in order to apply it to the interior clutch spring of the above embodiment. That is,
δ = D _A '-D _S '
D _A ': inner diameter of shaft and pulley D _S ': outer diameter of spring
By performing the above replacement, the values of the lock torque _TL and the idling torque T _S of the clutch spring 11 having the cross-sectional dimensions determined by applying the theoretical formula are confirmed by experiments, and the values substantially match the theoretical formula. I was assured. Therefore, by applying the above-described theoretical formula to the cross-sectional shape of the clutch spring 11 of the embodiment to a shape other than the example described above, it is possible to obtain a spring clutch having excellent lubricity.
[0043]
【The invention's effect】
As described above, in the present invention, the side surface of the coil portion is formed as a convex circular arc surface, so that the grease held inside the clutch spring can be disengaged from the contact surface of the coil portion by centrifugal force during rotation. The fluid can smoothly flow to the outer diameter side of the spring, and a large amount of grease can be held between the outer diameter portions of the arc surface of the coil portion. Therefore, the contact portion between the clutch spring and the clutch surface can be effectively lubricated with grease, and a long-life spring clutch having excellent lubrication can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional front view showing an embodiment of a spring clutch according to the present invention; FIG. 2 is a sectional view taken along the line II-II of FIG. 1 FIG. 3 is an enlarged view of a clutch spring portion of FIG. FIG. 4 (I) is a cross-sectional view of a square wire made of a two-sided pressed product, and (II) is a cross-sectional view of a square wire made of a four-sided pressed product. FIG. 5 is a longitudinal sectional front view showing a conventional spring clutch. [Explanation of symbols]
1 Pulley (input side member)
2 Pulley hub (output side member)
11 Clutch spring 11a Coil part 12 Arc surfaces 13a, 13b Cylindrical surface 14 Clutch surface

Claims (3)

In a clutch spring for a spring clutch in which a wire is wound in a helical shape and the side surfaces of coil portions that are continuous in the axial direction are in contact with each other, and the outer periphery and the inner periphery are cylindrical surfaces, at least one side surface of each of the coil portions is formed. A clutch spring for a spring clutch, wherein the clutch spring has a convex circular arc surface. The clutch spring for a spring clutch according to claim 1, wherein the wire is a two-sided pressed square wire obtained by pressing the two surfaces when the round wire is pulled out. A cylindrical clutch surface is provided on the inner periphery of the input-side member, and is axially continuous between the clutch surface and the output-side member incorporated inside the input-side member and relatively rotatably supported. Incorporate a clutch spring in which the side surfaces of the coil portion contact each other, make the cylindrical surface on the outer periphery of the clutch spring elastically contact the clutch surface, and when the input side member rotates in one direction, the clutch spring contacts the clutch surface. In a spring clutch in which the diameter is enlarged to be brought into pressure-contact engagement with a clutch surface and only one-way rotation of the input member is transmitted to the output member via the clutch spring, the side surface of the coil portion in the clutch spring is A spring clutch having a convex circular arc surface.

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