HK1174960A - Structure for locking electromagnetic clutch in phase changing device of engine - Google Patents

Description

Rotation stopping structure of electromagnetic clutch in phase variable device of engine

Technical Field

The present invention relates to a technology of a rotation stop structure of an electromagnetic clutch in a phase variable device of an engine in which a brake drum is rotated relative to a sprocket on a crank shaft side by the electromagnetic clutch, a relative phase angle of a camshaft relative to the sprocket is changed, and an opening/closing timing of a valve is changed.

Background

The phase variable device in the engine refers to a device as follows: a cam shaft, a sprocket on the crank shaft side and a brake drum are arranged coaxially with and relatively rotatable with respect to the cam shaft, and the electromagnetic clutch brakes the brake drum to cause a rotational delay with respect to the sprocket, thereby operating a phase variable mechanism such as a helical spline and changing the relative phase angle between the cam shaft and the sprocket to change the valve opening/closing timing.

Patent document 1 discloses an electromagnetic brake mounting structure of the phase variable device in the engine. The electromagnetic clutch (electromagnetic brake) of patent document 1 is supported by a cover (engine case: electromagnetic clutch cover), and is locked by inserting a plurality of pins protruding toward the back surface of the clutch case into holes of the cover as shown in fig. 3 and the like.

Documents of the prior art

Patent document

Patent document 1 Japanese laid-open patent publication No. 2008-19817

Disclosure of Invention

Problems to be solved by the invention

In the rotation stop structure of the electromagnetic brake attachment structure in patent document 1, since the rotation stop pin protrudes in the axial direction of the camshaft, the axial length of the conventional phase variable device is formed long. This becomes a problem in forming the axial length of the phase variable device compactly.

In view of the above problems, the present invention provides a rotation stop structure of an electromagnetic clutch that shortens the axial length thereof compared to the conventional one, in order to provide a phase variable device for an engine that saves space in the axial direction of a camshaft.

Means for solving the problems

In order to solve the above problems, a rotation stop structure of an electromagnetic clutch in a phase variable device of an engine according to claim 1 is a structure in which a sprocket rotated by a crankshaft and a brake drum are coaxially and relatively rotatably supported by a camshaft, respectively, and a circular electromagnetic clutch, which is coaxial with the brake drum and is held in a position facing the brake drum by rotation stop of an electromagnetic clutch cover, brakes the brake drum to change a relative phase angle between the camshaft and the crankshaft; the method is characterized in that: a holding portion of the electromagnetic clutch having a circumferential surface coaxial with the camshaft is provided on the electromagnetic clutch cover; the electromagnetic clutch is held in the holding portion so as to overlap in a radial direction of the peripheral surface via a substantially C-shaped leaf spring attached to the holding portion along the peripheral surface, and is locked with respect to the holding portion by a first locking means provided between the holding portion and the leaf spring and a second locking means provided between the leaf spring and the electromagnetic clutch.

The electromagnetic clutch is held by a holding portion on the electromagnetic clutch cover side via a substantially C-shaped plate spring. In this case, the electromagnetic clutch is disposed to overlap the holding portion in a radial direction of the circumferential surface of the holding portion. The electromagnetic clutch is held by the first and second rotation preventing means via a substantially C-shaped plate spring so as to be non-rotatable with respect to the holding portion. Since the substantially C-shaped plate spring and the first and second detent means hold the electromagnetic clutch and the electromagnetic clutch cover-side holding portion in a non-rotatable manner while being arranged in a radial direction (a direction orthogonal to the axial direction of the camshaft), a detent structure having a short axial length is formed, and a phase variable device having a short axial length can be realized.

Further, claim 2 is a rotation stop structure of an electromagnetic clutch in a phase variable device of an engine according to claim 1, wherein the first rotation stop means is a pair of concave and convex portions for fixing the plate spring to an electromagnetic clutch cover, the pair of concave and convex portions being composed of a convex portion provided on one of the electromagnetic clutch cover and the plate spring and protruding in a radial direction of a camshaft and a concave portion provided on the other of the electromagnetic clutch cover and the plate spring and engaging with the convex portion; the second rotation stopping means is a pair of concave and convex portions for fixing the electromagnetic clutch to the leaf spring in a rotation stopping manner, and the pair of concave and convex portions is composed of a convex portion provided on one of the electromagnetic clutch and the leaf spring and protruding in a radial direction of the camshaft, and a concave portion provided on the other of the electromagnetic clutch and the leaf spring and engaging with the convex portion.

The electromagnetic clutch is fixed to the electromagnetic clutch cover so as not to be rotatable via a leaf spring by providing rotation stopping means formed of projections and recesses that engage with each other in the radial direction of the electromagnetic clutch on the electromagnetic clutch cover side and the leaf spring side (first rotation stopping means) and on the electromagnetic clutch side and the leaf spring side (second rotation stopping means). Since the first and second rotation stop means are concave-convex portions that are concave or convex in the radial direction, the electromagnetic clutch can realize a rotation stop structure having a short axial length.

Claim 3 is the rotation stop structure of the electromagnetic clutch in the phase variable device for an engine according to claim 2, wherein the engaging surfaces of the convex portion and the concave portion have circular arc-shaped cross sections.

In the conventional rotation stop structure of the electromagnetic clutch disclosed in patent document 1, a rubber cushion member for relaxing an impact force generated when braking the brake drum needs to be provided between a rotation stop pin protruding toward the electromagnetic clutch and an electromagnetic clutch cover pin insertion hole serving as a receiving side. The rubber-made cushioning member is used at a high temperature and a very low temperature to a certain extent.

In the rotation stopping structure according to claim 3, the cross-sections of the concave-convex engaging surfaces formed between the electromagnetic clutch cover and the plate spring and between the plate spring and the electromagnetic clutch are formed in the arc shape, so that the impact force transmitted from the holding portion on the electromagnetic clutch cover side to the electromagnetic clutch during braking of the brake drum is relaxed without using the plate spring having a temperature around the use temperature.

Claim 4 is the rotation stop structure of the electromagnetic clutch in the phase variable device for an engine according to claim 3, wherein the curvature of the concave portion is formed larger than the curvature of the convex portion.

If the curvature of the concave portion is made larger than that of the convex portion, the convex portion is pushed into the concave portion to be engaged with the concave portion, and therefore, the engagement of the convex portion with the concave portion becomes stronger.

Further, when the convex portion and the concave portion are engaged, the plate spring is pulled in the circumferential direction, and a force is applied to the electromagnetic clutch in the direction toward the center of the electromagnetic clutch holding portion, so that the center of the electromagnetic clutch is positioned so as to coincide with the center of the electromagnetic clutch holding portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the rotation stop structure of the electromagnetic clutch in the phase variable device for an engine of claim 1, since the rotation stop structure of the electromagnetic clutch is formed by the plate spring arranged in the radial direction of the applying means, the axial length of the rotation stop structure is shortened, and thus the phase variable device for an engine in which space is saved in the axial direction of the camshaft can be provided.

The rotation stop structure of the electromagnetic clutch according to claim 2 is configured by the radial projections and recesses provided between the electromagnetic clutch and the plate spring and between the plate spring and the electromagnetic clutch cover, and therefore the axial length of the rotation stop structure is shortened, and a phase variable device of an engine which can save space in the axial direction of the camshaft can be provided.

According to the rotation stop structure of the electromagnetic clutch according to claim 3, the usable buffer member made of rubber or the like whose upper and lower temperatures are restricted is not used, but the plate spring made of a metal member or the like whose temperature is not controlled to the right or left is used, and thus the electromagnetic clutch can be used at a high temperature or a very low temperature which has been difficult to use.

According to the rotation stop structure of the electromagnetic clutch of claim 4, the engagement of the convex portion with the concave portion becomes stronger, and the electromagnetic clutch is more reliably fixed to the electromagnetic clutch cover. Further, the center of the electromagnetic clutch is positioned so as to coincide with the center of the electromagnetic clutch holder.

Drawings

Fig. 1 is a perspective view showing an embodiment of a phase variable device of an engine using a rotation stop structure of an electromagnetic clutch according to the present invention.

Fig. 2 is an exploded perspective view of fig. 1.

Fig. 3 is an axial sectional view of fig. 1.

Fig. 4 is a radial sectional view of the phase variable device (retarded angle gauge) of the first embodiment in an initial state, in which (a) is a sectional view a-a of fig. 3 showing the arrangement of the first eccentric circular cam, and (B) is a sectional view B-B of fig. 3 showing the arrangement of the second eccentric circular cam in the retarded angle gauge.

Fig. 5 is a radial sectional view of the phase variable device (retardation angle specification) of the first embodiment after the change of the assembly angle, and (a) is a sectional view a-a of fig. 3, and (B) is a sectional view B-B of fig. 3.

Fig. 6 is a sectional view showing the arrangement of the second eccentric circular cam in the advanced angle standard, (a) is a sectional view B-B of fig. 3 in an initial state, and (B) is a sectional view B-B of fig. 3 after the assembly angle is changed.

Fig. 7 is a radial sectional view of the reverse rotation mechanism in an initial state, and (a) is a sectional view C-C of fig. 3, (b) is a sectional view D-D of fig. 3, and (C) is a sectional view E-E of fig. 3.

Fig. 8 is a radial sectional view of the counter rotating mechanism after the assembly angle is changed, (a) is a sectional view C-C of fig. 3, (b) is a sectional view D-D of fig. 3, and (C) is a sectional view E-E of fig. 3.

Fig. 9 is an exploded perspective view showing a rotation stop structure of the electromagnetic clutch.

Fig. 10 is an axial cross-sectional view showing a rotation stop structure of the electromagnetic clutch.

Detailed Description

Preferred mode for carrying out the invention

First, an embodiment of a phase variable device using a rotation stop structure of an electromagnetic clutch according to the present invention will be described with reference to fig. 1 to 8. A phase variable device of an engine is a device that changes the opening/closing timing of intake and exhaust valves of the engine that open and close in conjunction with a camshaft by changing the assembly angle (relative phase angle) between a sprocket and the camshaft that are rotated by a crankshaft and that are assembled to the engine by an assembly angle changing mechanism.

The phase varying device 30 of the engine in the embodiment is composed of the driving rotary body 31, the intermediate shaft 32, the first brake drum 34, the assembly angle varying mechanism 65, and the rotational operation force applying means 66, which are disposed on the rotational center axis L0, respectively. The assembly angle changing mechanism 65 is constituted by the first eccentric circular cam 41, the cam guide member 33, and the second eccentric circular cam 46. The rotational operation force imparting means 66 is constituted by the first electromagnetic clutch 35 and the counter rotation mechanism 57. In the following description, the second electromagnetic clutch 56 side in fig. 2 is referred to as the apparatus front side, the sprocket 36 side is referred to as the apparatus rear side, the rotational direction of the driving rotary body 31 viewed from the front side of the apparatus is referred to as the clockwise direction D1 (advanced angle direction), and the opposite direction to D1 is referred to as the counterclockwise direction D2 (retarded angle direction).

The driving rotor 31 is integrally formed by 2 sprockets (36, 37) and a driving cylinder 40, and is rotated by a driving force of a crankshaft. The sprockets (36, 37) have circular holes (36 a, 37 a) in the centers thereof. An inner flange portion 37b is provided inside the circular hole 37 a. A disc spring 42 having a circular hole 42a at the center thereof is engaged with a circular hole 37c provided at the center of the inner flange portion 37b, and a holder 43 having a circular hole 43a at the center thereof is engaged with the circular hole 37a from the front.

On the other hand, the drive cylinder 40 is formed by integrating a cylindrical portion 40a and a bottom portion 40 b. A pair of substantially radial guide grooves (47, 47) are provided in the bottom portion 40b at positions symmetrical with the circular hole 40c in the center portion interposed therebetween. In the following description, an extension line passing through the rotation center axis L0 of the drive cylinder 40 and extending along the substantially radial guide grooves (47, 47) is referred to as L3 (see fig. 4 a).

Sprocket 36 is integrated with sprocket 37 by coupling pin 38, and sprocket 37 is integrated with drive cylinder 40 by coupling pin 39.

The intermediate shaft 32 is integrated by coupling the front end cylindrical portion 45a to the coupling hole 32e at the rear end portion and screwing the bolt 44 inserted into the bolt insertion hole 32d to the camshaft 45, and has a shape in which the small cylindrical portion 32a, the middle cylindrical portion 32b, the second eccentric circular cam 46, and the large cylindrical portion 32c are continuous in the direction of the rotation axis L0 from the front.

The driving rotor 31 is supported on the intermediate shaft 32 by inserting the large cylindrical portion 32c of the intermediate shaft 32 into the circular holes (36 a, 42a, 43 a) and inserting the cylindrical portion 32b into the circular hole 40c, and is supported so as to be rotatable relative to the camshaft 45.

The second eccentric circular cam 46 is disposed adjacent to the bottom 40b of the drive cylinder 40 with its center axis L2 eccentric by a distance d2 from the rotation center axis L0 of the intermediate shaft 32, and eccentrically rotates around the rotation center axis L0 integrally with the intermediate shaft 32.

On the other hand, the cam guide member 33 has a pair of grips (48, 48) and an oblong hole 49 that protrude from the outer peripheral end toward the front of the apparatus. The gripping portions are formed with substantially the same width and at substantially the same interval as the substantially radial guide grooves (47, 47) of the drive cylinder 40. The oblong hole 49 is formed so as to extend in a direction L4 orthogonal to a line connecting the gripping portions (48, 48) (see fig. 4 (b)). The upper and lower portions of the outer peripheral surface of the second eccentric circular cam 46 are in sliding contact with the inner peripheral surface of the oblong hole 49.

The cam guide member 33 is disposed between the sprocket 37 and the drive cylinder 40, and is supported on the intermediate shaft 32 by a second eccentric circular cam 46 inserted into the oblong hole 49. The grip portions (48, 48) are engaged with the substantially radial guide grooves (47, 47), and the tips thereof protrude forward from the substantially radial guide grooves (47, 47). The holding portions (48, 48) are displaced in the radial direction of the drive cylinder 40 along the substantially radial guide grooves (47, 47) if the second eccentric circular cam 46 eccentrically rotates in the oblong hole 49.

The first brake drum 34 is inserted inside the cylindrical portion 40a, and the outer peripheral surface 34a is supported by the cylindrical portion inner peripheral surface 40e and rotates relative to the drive cylinder 40 about the rotation center axis L0. Further, the first brake drum 34 is provided with a first eccentric circular cam 41 projecting from the rear surface toward the rear of the apparatus, and a circular hole 34b through which the middle cylindrical portion 32b of the intermediate shaft 32 is inserted is provided at the center.

The first eccentric circular cam 41 eccentrically rotates around the rotation center axis L0 integrally with the first brake drum 34 by an eccentric distance d1 from the rotation center axis L0 (eccentric point) of the first brake drum 34 with its center axis L1 (eccentric point). The outer periphery of the first eccentric circular cam 41 is gripped inside gripping portions (48, 48) protruding from substantially radial guide grooves (47, 47).

A first electromagnetic clutch 35 and a counter rotation mechanism 57 are provided in front of the first brake drum 34. The first electromagnetic clutch 35 (first brake unit) has a ring shape and is fixed by an electromagnetic clutch cover 70, which will be described later, at a position coaxial with the rotation center axis L0 and facing the front surface (adsorption surface 34 c) of the first brake drum. When the coil 35a is energized, the ring-shaped first electromagnetic clutch 35 sucks the front surface (suction surface 34 c) of the first brake drum 34 rotating together with the driving rotary body 31 and brings the front surface into sliding contact with the friction member 35 b.

The counter rotation mechanism 57 is constituted by the second brake drum 54, the second electromagnetic clutch 56, and the ring mechanism 67. The ring mechanism 67 is constituted by the first ring member 50, the intermediate rotating body 51, the movable member 52, and the second ring member 53 and the second brake drum 54 arranged in the stepped circular hole 54c at the rear of the second brake drum 54.

The first brake drum 34 is provided with a stepped circular hole 34d on the front face. A first eccentric circular hole 34f having a stepped shape is provided at a bottom 34e of the stepped circular hole 34 d. The center O1 of the first eccentric circular hole 34f is eccentric from the rotation center axis L0 of the intermediate shaft 32 by a distance d 3. The first annular member 50 is slidably rotatably inscribed in the eccentric circular hole 34 f. The first ring member 50 has a first engaging hole 50a opened in the front surface.

The intermediate rotating body 51 has a square hole 51a at the center thereof and a substantially radial guide groove 51b extending in the radial direction of the intermediate rotating body 51 on the outer side thereof. The intermediate rotating body 51 is engaged with the flat engaging surfaces (32 f, 32 g) of the intermediate shaft 32 through the square holes 51a, and is fixed to the intermediate shaft 32 in a non-rotatable state. An extension line extending along the substantially radial guide groove 51b through the rotation center axis L0 of the intermediate rotor 51 is L5 (see fig. 7).

The second brake drum 54 includes a circular hole 54a at the center and a stepped second eccentric circular hole 54c on the rear side with the center O2 eccentric by a distance d4 from the rotation center axis L0. The second brake drum 54 is rotatably supported on the intermediate shaft 32 by the small cylindrical portion 32a inserted into the circular hole 54 a. The second annular member 53 is slidably rotatably inscribed in the second eccentric circular hole 54 c. The second annular member 53 has a second engagement hole 53a formed therein and opened at the rear surface. The first and second annular members (50, 53) are arranged with centers (O1, O2) on both sides of the extension line L5.

The movable member 52 is configured by inserting the thin circular shaft 52a into the center of the hollow thick circular shaft 52 b. The thin circular shaft 52a has both ends slidably engaged with the first and second engaging holes (50 a, 53 a), and connects the first and second annular members (50, 53). The hollow round shaft 52b is displaced along the engaged substantially radial guide groove 51 b.

A retainer 55 is disposed at the tip of the small cylindrical portion 32a of the intermediate shaft 32 protruding from the circular hole 54 a. The members of fig. 2 extending from the retainer 55 to the sprocket 36 are held by the cam shaft 45 by inserting the bolts 44 from the front into holes formed in the centers thereof and screwing the bolts to the tip end of the cam shaft 45 (see fig. 3).

The second electromagnetic clutch 56 has a ring shape and is fixed by an electromagnetic clutch cover 70, which will be described later, at a position coaxial with the rotation center axis L0 and facing the front surface of the second brake drum 54. When the coil 56a is energized, the second electromagnetic clutch 56 sucks the suction surface 54b on the front surface of the second brake drum 54 and slidingly contacts the friction member 56b, thereby braking the rotation of the second brake drum 54.

Next, the operation of the phase varying apparatus 30 will be described. In an initial state before the assembly angle is changed (hereinafter, simply referred to as an initial state), the intermediate shaft 32, the cam guide member 33, and the first brake drum 34 rotate in the direction D1 together with the driving rotary body 31 that receives a driving force from a crankshaft (not shown) and rotates around the rotation center axis L0.

When the first electromagnetic clutch 35 is operated, the first brake drum 34 is braked by the contact of the attraction surface 34c with the friction member 35b, and rotates in the retarded angle direction D2 (see fig. 2 and 4) relative to the driving rotary member 31.

At this time, the first eccentric circular cam 41 in fig. 4 (a) eccentrically rotates in the counterclockwise direction D2 around the rotation center axis L0 integrally with the first brake drum 34. The gripping portions (48, 48) of the cam guide member 33 are displaced in the downward direction D3 along the substantially radial guide grooves (47, 47) by the first eccentric circular cam 41 which is in sliding contact with the inside. The cam guide member 33 descends in the direction D3 integrally with the grip portions (48, 48).

As shown in fig. 4 (b), if the cam guide 33 descends, the second eccentric circular cam 46 receives a force from the oblong hole 49 and eccentrically rotates counterclockwise D2. The intermediate shaft 32 (the cam shaft 45) is integrated with the second eccentric circular cam 46, and therefore rotates relative to the driving rotary member 31 in the direction D2. As a result, the assembly angle of the cam shaft 45 with respect to the driving rotor 31 (not shown) changes from the initial position to the counterclockwise direction D2 (retarded angle direction), and the valve opening/closing timing is changed.

On the other hand, the changed assembly angle is returned in the direction of the initial position by operating the second electromagnetic clutch 56 of the reverse rotation mechanism 57.

When the second electromagnetic clutch 56 shown in fig. 2 is operated, the second brake drum 54 of fig. 7 (a) braked by the second electromagnetic clutch 56 is rotated relative to the intermediate rotating body 51 and the first brake drum 34 in the retarded angle direction D2 with a delay in rotation. The second annular member 53 slides inside the second eccentric circular hole 54c, displacing the movable member 52 downward (in the direction D3 of fig. 7 (b)) along the substantially radial guide groove 51 b. In the first annular member 50 of fig. 7 (c), if the movable member 52 is displaced in the direction D3, it slides inside the first eccentric circular hole 34f, and a relative rotational torque in the direction D1 is applied to the first brake drum 34. As a result, the first brake drum 34 rotates relative to the driving rotary member 31 in the advance direction (direction D1) in reverse to the operation of the first electromagnetic clutch 35.

When the first brake drum 34 is relatively rotated in the advance direction D1 with respect to the driving rotary body 31, the first eccentric circular cam 41 is eccentrically rotated in the clockwise direction D1 about the rotation center axis L0 as shown in fig. 5 (a), and the grip portions (48, 48) and the cam guide member 33 are raised in the direction D4 along the substantially radial guide grooves (47, 47). The second eccentric circular cam 46 (intermediate shaft 32) of fig. 5 (b) rotates relative to the driving rotary member 31 in the advance direction (direction D1) if the cam guide member 33 is lifted. As a result, the assembly angle of the crankshaft with respect to the driving rotor 31 returns in the direction of the initial position, and the valve opening/closing timing is restored.

Next, a rotation stop structure of an electromagnetic clutch of a phase variable device according to the present application will be described. The rotation stop structure of the electromagnetic clutch in the present embodiment is configured as shown in the drawing.

Reference numeral 70 denotes a metallic (aluminum or the like) electromagnetic clutch cover that fixes the first electromagnetic clutch 35 and the second electromagnetic clutch 56 to an engine (not shown). In the drawings, the electromagnetic clutch cover 70 side is described as the vehicle front side, and the second electromagnetic clutch 56 side is described as the vehicle rear side. The electromagnetic clutch cover 70 is formed by integrating a top plate 70a, a horizontally oblong cylindrical portion 70b extending in a direction perpendicular to the rotation center axis L0 of the camshaft, and a flange portion 70c at the rear end opening edge portion. The top plate 70a is provided with a first holding portion 71 that holds the first electromagnetic clutch 35 and a second holding portion 72 that supports the second electromagnetic clutch 56.

The second holding portion 72 protrudes rearward from the top plate 70a, is formed in a substantially cylindrical shape having a cutout portion 72a in a part thereof in the axial direction, and has a step portion 72c recessed inward in the radial direction of the camshaft in the circumferential direction on the outer peripheral surface 72b thereof, along the same axis (central axis L0) as the first and second electromagnetic clutches (35, 56). Further, the outer circumferential surface 72b is provided with recesses 72d, which are formed at a plurality of locations equally divided in the circumferential direction and have an arc-shaped cross section (a cross section orthogonal to the axial direction, the same applies hereinafter) from the outer circumferential surface 72b to the step portion 72 c.

In the step portion 72c, a second plate spring 74 formed of stainless steel or the like and having the same width as the step portion 72c is attached along the step portion 72c, and is positioned in the axial direction. The second plate spring 74 is bent in a C-shape, has wave-shaped convex portions (74 a, 74 b) protruding inward and outward in the radial direction of the camshaft at a plurality of equally spaced portions in the circumferential direction, and has inwardly folded portions (74C, 74 d) at both ends. The radially inward convex portions 74a are formed at the same intervals as the plurality of concave portions 72d of the second holding portion 72, and are formed in a cross-sectional circular arc shape having a smaller curvature than the concave portions 72 d. The second plate spring 74 is configured such that the convex portions 74a are aligned with the corresponding concave portions 72d, and the folded portions (74 c, 74 d) are engaged with the notch portion 72a while the convex portion 74a on the plate spring side having a small curvature is pushed into the concave portion 72d having a large curvature and engaged therewith. As a result, the second leaf spring 74 is locked and fixed to the second holding portion 72 by securely engaging the convex portion 74a on the second leaf spring 74 side with the concave portion 72d (first rotation locking means) on the second holding portion 72 side. Since the second electromagnetic clutch 56, the second plate spring 74, and the second holding portion 72 are arranged to overlap each other on the radially outer side, the axial length (depth) of the rotation stop mechanism can be made short.

Further, on the inner peripheral surface 56a of the ring-shaped second electromagnetic clutch 56, concave portions 56b are provided at a plurality of circumferentially equally divided locations at the same intervals as the radially outward convex portions 74b of the second plate spring 74. The concave portion 56b is a concave portion extending in the axial direction and having an arc-shaped cross section, and is formed with a curvature larger than that of the convex portion 74 b.

The second electromagnetic clutch 56 is configured such that each concave portion 56b is aligned with a corresponding convex portion 74b of the second plate spring 74, and the convex portion 74b on the plate spring side having a small curvature is pushed into and engaged with the concave portion 56b having a large curvature. As a result, the second electromagnetic clutch 56 is securely engaged with the convex portion 74b on the second plate spring side and the concave portion 56b (second rotation stop means) on the second electromagnetic clutch 56 side, is retained by the second plate spring 74, and is fixed to the second retaining portion 72 by rotation stop. Further, a small gap of about 1mm is secured between the second electromagnetic clutch 56 and the top plate 70a, and the second electromagnetic clutch is displaced in the axial direction of the central axis L0 within the range of the small gap by using the concave portion 56b and the convex portion 74b as guides.

On the other hand, a first holding portion 71 for holding the first electromagnetic clutch 35 is provided around the second electromagnetic clutch 56 fixed to the second holding portion 72. The first holding portion 71 is a holding portion in which an axial step portion 71a provided to protrude from the top plate 70a toward the vehicle rear side and a spring holder portion 71b provided rearward thereof are integrally formed. The spring receiver portion 71b has an inner peripheral surface 71c formed substantially along the inner peripheral surface 70d of the cylindrical portion. The inner peripheral surface 71C has a diameter of a length obtained by adding the diameter of the first electromagnetic clutch 35 to the thickness × 2 of the first plate spring 73 and a substantially C-shaped cross section obtained by cutting a part of the inner peripheral surface.

Further, a step portion 71d is provided on the inner circumferential surface 71c in the circumferential direction so as to be recessed radially outward from the boundary with the step portion 71 a. Further, the inner circumferential surface 71c is provided with recesses 71e having an arc-shaped cross section formed to reach the step portion 71d in the axial direction at a plurality of equally divided portions in the circumferential direction.

In the step portion 71d, a first plate spring 73 formed of stainless steel or the like and having the same width as the step portion 71d is attached along the step portion 71d, and is positioned in the axial direction. The first plate spring 73 is bent in a C-shape, has wavy convex portions (73 a, 73 b) protruding radially inward and outward at a plurality of circumferentially equally divided portions, and has outwardly folded portions (73C, 73 d) at both ends. The radially outward convex portions 73a are formed at the same intervals as the plurality of concave portions 71e of the first holding portion 71, and are formed in a cross-sectional arc shape having a smaller curvature than the concave portions 71 e. The first plate spring 73 is configured such that the convex portions 73a are aligned with the corresponding concave portions 71e, and the folded portions (73 c, 73 d) are engaged with both end portions (71 f, 71 g) of the inner peripheral surface 71c while the convex portion 73a on the plate spring side having a smaller curvature is pushed into and engaged with the concave portion 71e having a larger curvature. As a result, the first leaf spring 73 is locked with respect to the first holding portion 71 by securely engaging the convex portion 73a on the first leaf spring 73 side with the concave portion 71e (first locking means) on the first holding portion 71 side. The rotation stop mechanism of the first electromagnetic clutch 35 can be formed to have a short axial length (depth) as in the second electromagnetic clutch 56.

Further, on the outer peripheral surface 35c of the ring-shaped first electromagnetic clutch 35, concave portions 35d are provided at a plurality of circumferentially equally divided locations at the same intervals as the radially inward convex portions 73b of the first plate spring 73. The concave portion 35d is a concave portion extending in the axial direction and having an arc-shaped cross section, and is formed with a curvature larger than that of the convex portion 73 b.

The first electromagnetic clutch 35 is configured such that the concave portions 35d are respectively matched with the corresponding convex portions 73b of the first leaf spring 73, and the convex portions 73b on the leaf spring side having a small curvature are pushed into and engaged with the concave portions 71e having a large curvature. As a result, the first electromagnetic clutch 35 is securely engaged with the convex portion 73b on the first plate spring side and the concave portion 35d (second rotation stop means) on the first electromagnetic clutch 35 side, is retained by the first plate spring 73, and is fixed to the first retaining portion 71 by rotation stop. Further, a small gap of about 1mm is secured between the first electromagnetic clutch 35 and the stepped surface 71h of the stepped portion 71a, and the second electromagnetic clutch is displaced in the axial direction of the central axis L0 within the range of the small gap by using the concave portion 35d and the convex portion 73b as guides.

In the present embodiment, the rotation stopper means (73 a, 71e, etc.) are formed by concave-convex portions having an arc-shaped cross section, but concave-convex portions having a triangular or quadrangular cross section may be used. However, the cross-sectional shape of the uneven portion is preferably a circular arc shape as compared with the above-described shape having an angle. If the cross section of the uneven portion is formed in an arc shape, the impact force transmitted from the holding portion of the electromagnetic clutch to the electromagnetic clutch during braking is alleviated. Further, since the plate spring serving as the damper member is a steel spring that is not subjected to a use temperature, the rotation stop mechanism of the electromagnetic clutch according to the present embodiment can be used at a higher temperature than the conventional one.

In the present embodiment, the number of the wavy projections (73 a, 73 b) of the first plate spring 73 provided at a plurality of circumferentially equally divided locations (2 locations in the present embodiment) is made smaller than the number of the wavy projections (74 a, 74 b) of the second plate spring 74 (4 locations in the present embodiment). This is because the inner peripheral surface diameter of the first holding portion 71 to which the plate spring is attached is larger than the outer peripheral surface diameter of the second holding portion 72, and the torque required for the rotation stop of the electromagnetic clutch is only required to be small. That is, it is preferable that the leaf spring is attached to the outer peripheral surface of the electromagnetic clutch to reduce the number of the wavy projections formed for rotation stop and to simplify the manufacturing time and labor, as compared with the leaf spring attached to the inner peripheral surface of the electromagnetic clutch.

The rotation stopping structure of the electromagnetic clutch in the present embodiment is adopted in a double clutch mechanism including the second electromagnetic clutch 56 in the reverse rotation mechanism of the brake drum 34 in addition to the first electromagnetic clutch 35, but it is needless to say that the double clutch mechanism may be applied to a mechanism using a single electromagnetic clutch such as a coil spring in the reverse rotation mechanism.

Description of the symbols

30 phase variable device of engine

34 first brake drum

35 first electromagnetic clutch

35 d: concave part (second rotation-stopping unit)

36. 37 chain wheel

45: camshaft

54 second brake drum

56 second electromagnetic clutch

56b concave part (second rotation stop unit)

70 electromagnetic clutch cover

71 first holding part of electromagnetic clutch

71c inner peripheral surface (circumferential surface)

71e recess (first rotation stop unit)

72 second holding part of electromagnetic clutch

72b outer peripheral surface (circumferential surface) of the second holding portion

72d recess (first rotation stop unit)

73 first leaf spring

73a radial outward projection (first rotation stop unit)

73b radially inward projection (second detent unit)

74 second plate spring

74a radially inward projection (first rotation stop means)

74b radially outward convex portion (second rotation stop unit)

L0 center axis of rotation of camshaft

Claims (4)

1. A rotation stop structure of an electromagnetic clutch in a phase variable device of an engine, in the phase variable device of the engine, a chain wheel rotating by a crankshaft and a brake drum are respectively supported by a camshaft coaxially and relatively rotatably, a circular electromagnetic clutch coaxial with the brake drum and held in a position opposite to the brake drum by an electromagnetic clutch cover is used for braking the brake drum, and a relative phase angle between the camshaft and the crankshaft is changed;

the method is characterized in that: a holding portion of the electromagnetic clutch having a circumferential surface coaxial with the camshaft is provided on the electromagnetic clutch cover;

the electromagnetic clutch is held in the holding portion so as to overlap in a radial direction of the peripheral surface via a substantially C-shaped leaf spring attached to the holding portion along the peripheral surface, and is locked with respect to the holding portion by a first locking means provided between the holding portion and the leaf spring and a second locking means provided between the leaf spring and the electromagnetic clutch.

2. The rotation stop structure of the electromagnetic clutch in the phase variable device of the engine according to claim 1, characterized in that:

the first rotation stopping means is a pair of concave-convex portions for fixing the plate spring to the electromagnetic clutch cover in a rotation stopping manner, the pair of concave-convex portions being constituted by a convex portion provided on one of the electromagnetic clutch cover and the plate spring and protruding in a radial direction of the camshaft, and a concave portion provided on the other of the electromagnetic clutch cover and the plate spring and engaging with the convex portion;

the second rotation stopping means is a pair of concave and convex portions for fixing the electromagnetic clutch to the leaf spring in a rotation stopping manner, and the pair of concave and convex portions is composed of a convex portion provided on one of the electromagnetic clutch and the leaf spring and protruding in a radial direction of the camshaft, and a concave portion provided on the other of the electromagnetic clutch and the leaf spring and engaging with the convex portion.

3. The rotation stop structure of the electromagnetic clutch in the phase variable device of the engine according to claim 2, characterized in that: the cross section of the engaging surface of the convex portion and the concave portion has a circular arc shape.

4. The rotation stop structure of the electromagnetic clutch in the phase variable device of the engine according to claim 3, characterized in that: the curvature of the concave portion is larger than the curvature of the convex portion.