JP2012215254A - Pulley unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulley unit capable of easily and surely fixing both ends of a torsion coil spring to a shaft body and a pulley even when the cross section of a spring material is comparatively large.SOLUTION: The pulley unit includes: the shaft body 1 having a first recessed part 10 for holding a spring formed on its outer peripheral surface; the pulley 3 having a second recessed part 13 for holding the spring formed on its inner circumferential surface, and rotatably supported around the shaft body 1 by bearings 5 and 6; the coil spring 7 disposed in an annular space between the shaft body 1 and the pulley 3, and having a first hook part 7a that is formed at one end part thereof and is bent inwardly in a radial direction to fit in the first recessed part 10 for holding the spring and a second hook part 7b that is formed at the another end part thereof and is bent outwardly in the radial direction to fit in the second recessed part 13 for holding the spring; a bushing 12 for fixing the first hook part fitted between the outer periphery of the one end of the coil spring 7 and the inner periphery of the pulley 3; and a cylindrical member 4c for fixing the second hook part fixed to the pulley 3 and fitted in the inner periphery of the other end of the coil spring 7.

Description

  The present invention relates to a pulley unit used for transmitting, for example, the rotation of an automobile engine to an auxiliary machine such as an alternator via a belt, between a shaft body and a pulley disposed around the shaft body. The present invention relates to a pulley unit in which a torsion coil spring capable of transmitting torque by absorbing rotational fluctuation is interposed.

  As a pulley unit of this type, conventionally, a one-way spring clutch and a torsion coil spring are interposed between a shaft body connected to an auxiliary machine and a belt pulley rotatably supported by a bearing around the shaft body. What was made to be known was known (for example, refer to Patent Document 1).

  The one-way spring clutch transmits torque from the pulley to the shaft body, and the rotational torque of the pulley is transmitted to the shaft body via the clutch and the coil spring.

  In such a conventional pulley unit, friction and wear due to a one-way spring clutch become a problem, and a one-way spring clutch is eliminated and torque is transmitted only by a torsion coil spring (for example, Patent Documents). 2).

Special table 2008-528906 JP 2008-169895 A

  In the pulley unit shown in Patent Document 2, it is necessary to fix the end of the torsion coil spring to the shaft body or the pulley.

  As a means for easily fixing the end portion of the torsion coil spring to the shaft body or the like, it is conceivable to form a hook portion by bending the end portion at a right angle and hook it on a groove-shaped recess formed in the shaft body or the like.

  On the other hand, when the shaft body is connected to a rotating body having a large moment of inertia such as an alternator, it is necessary to increase the rigidity of the spring so that a large torque can be transmitted. However, in order to increase the rigidity of the torsion coil spring, it is necessary to increase the cross-sectional area of the spring material (the wire material constituting the spring), which makes it difficult to bend the end of the spring at a right angle. Fixing the part is also difficult.

  An object of the present invention is to provide a pulley unit that solves the above-described problems and can easily and reliably fix both end portions of a torsion coil spring to a shaft body and a pulley even if the cross-sectional area of the spring material is relatively large. There is.

  The pulley unit according to the present invention has a shaft body having a spring holding first recess formed on the outer peripheral surface and a spring holding second recess formed on the inner peripheral surface, and is rotatably supported by a bearing around the shaft body. And a first hook portion that is disposed in an annular space between the shaft body and the pulley and is bent radially inward at one end portion and fitted into the first recess for holding the spring, and the other end portion A coil spring formed with a second hook portion bent radially outward and fitted in the second recess for holding the spring, and fitted between the outer periphery of the one end of the coil spring and the inner periphery of the pulley. A first hook fixing bush; and a second hook fixing cylindrical member fixed to the pulley and fitted on an inner periphery of the other end of the coil spring. is there.

  The first hook portion fixing bush fitted between the outer periphery of the one end portion of the coil spring and the inner periphery of the pulley prevents the first hook portion fitted in the spring holding first recess from being deformed outward in the radial direction. The first hook portion is securely fixed to the shaft body. The second hook portion fixing tubular member fitted on the inner periphery of the other end portion of the coil spring prevents the second hook portion fitted in the second concave portion for holding the spring from being deformed inward in the radial direction. Is securely fixed to the pulley. For this reason, even if the cross-sectional area of the spring material is relatively large and the hook portions cannot be bent at a right angle, the hook portions can be easily and reliably fixed to the shaft body and the pulley. Of course, even when both hook portions are bent at a right angle, this can be securely fixed by the shaft body and the pulley.

  The first hook portion fixing bush may be an endless annular shape or may be an arc shape (circular shape).

  The endless annular bush is preferably arranged so as to be rotatable with respect to the shaft and the pulley. In this case, the bush rotates between the shaft and the pulley, so that lubrication means such as a lubricant is added to a material having lubricity and a certain degree of strength, for example, phosphor bronze or steel. Is preferred.

  In order to increase the transmission torque of the coil spring, it is preferable to increase its outer diameter as much as possible so that it is close to the inner diameter of the pulley as long as the rotational fluctuation function is not impaired. When the inner diameter of the inner circumference of the pulley in which the endless annular bush is accommodated is constant, the outer diameter of the coil spring is uniform in an unloaded state where no external force is applied to the coil spring, and is close to the inner diameter of the pulley. If this is the case, the portion of the coil spring inside the bush is always elastically deformed by the thickness of the bush, and the bush is firmly sandwiched between the shaft body and the pulley. In order to avoid this, it is preferable to make the outer diameter of the coil spring portion inside the bush smaller than the other portions.

  If the coil spring is formed in an arc shape, the portion of the coil spring inside the bush is shortened, the portion of which the outer diameter is reduced is small, and the transmission torque of the coil spring can be increased as much as possible.

  The arc-shaped bush must always be in contact with the outer periphery of the first hook portion of the spring. For this reason, it is preferable to rotate integrally with the coil spring.

  In the pulley unit of the present invention, for example, the first hook fixing bush has an arc shape, and one end thereof has a protrusion that overlaps the outer periphery of the one end of the coil spring and extends inward in the radial direction. And the protrusion is sandwiched between the first recess for holding the spring and the outer peripheral surface of the coil spring.

  If it does in this way, a bush will rotate in one with a coil spring, and the 1st hook part will be securely fixed to the 1st crevice by the projection part of a bush.

  According to the electric motor unit of the present invention, as described above, both ends of the torsion coil spring can be easily and reliably fixed to the shaft body and the pulley even when the cross-sectional area of the spring material is relatively large.

FIG. 1 is a longitudinal sectional view of a pulley unit showing a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is an exploded perspective view showing main components of the pulley unit of FIG. FIG. 5 is a cross-sectional view corresponding to FIG. 2 showing a second embodiment of the present invention. FIG. 6 is a perspective view of a first hook portion fixing bush constituting the pulley unit of FIG. 5.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 4 show a first embodiment. In the following description, the left side of FIG. 1, which is a longitudinal sectional view of the pulley unit, is the front and the right side is the rear.

  The pulley unit consists of a shaft (1) that is an inner rotating body, a pulley (3) and a pulley cover (4) that constitute the outer rotating body (2), two sets of bearings (5) and (6), and rotational fluctuation absorbing A torsion coil spring (7) is provided.

  The shaft body (1) has a hollow shape, and is divided into a front small-diameter portion (1a) that is relatively long and has a small outer diameter, and a rear large-diameter portion (1b) that is relatively short and has a large outer diameter. . Although not shown in detail, rotation prevention means such as a screw is provided on the inner periphery of the shaft body (1), and this portion is connected to the shaft of the alternator.

  The pulley (3) has a cylindrical shape. A relatively thick inward flange portion (3a) is integrally formed at the inner peripheral rear end portion of the pulley (3), and the inner diameter of the portion in front of the flange portion (3a) is constant. A portion of the outer periphery of the pulley (3) excluding the front portion is a belt receiving portion (3b) having a larger outer diameter than the front portion and formed with a plurality of belt annular grooves.

  The pulley cover (4) is integrally formed with an outer cylindrical portion (4b) and an inner cylindrical portion (4c) extending rearward on the outer peripheral edge and inner peripheral edge of the perforated disc-shaped front wall (4a), respectively. It is a double cylinder. The outer cylindrical portion (4b) of the pulley cover (4) is closely fitted on the outer periphery of the front portion of the pulley (3), and is fixed by an appropriate means.

  The front bearing (5) is a needle roller bearing with a cage, and is between the outer periphery of the small diameter portion (1a) of the shaft body (1) and the inner periphery of the inner cylindrical portion (4c) of the pulley cover (4). Is provided. The rear bearing (6) is a ball bearing with a cage and is provided between the outer periphery of the large-diameter portion (1b) of the shaft body (1) and the inner periphery of the flange portion (3a) of the pulley (3). It has been. In this example, the large diameter portion (1b) is the inner ring of the bearing (6), and the flange portion (3a) is the same outer ring. An oil seal (8) is provided between the small diameter portion (1a) of the shaft body (1) in front of the bearing (5) and the inner cylindrical portion (4c) of the pulley cover (4). A seal member (9) is provided between the large diameter portion (1b) of the shaft body (1) on the rear side of the bearing (6) and the pulley (3). The pulley (3) is supported by the front and rear bearings (5) and (6) so as to be able to rotate relative to the shaft body (1).

  The outer diameter of the inner cylindrical portion (4c) of the pulley cover (4) is substantially equal to the outer diameter of the large diameter portion (1b) of the shaft body (1). Further, the inner diameter and outer diameter of the relatively long portion on the rear side of the inner cylindrical portion (4c) are slightly smaller than those of the portion closer to the front end.

  The spring (7) consists of the outer periphery of the large-diameter portion (1b) of the shaft body (1), the outer periphery of the inner cylindrical portion (4c) of the pulley cover (4), and the pulley (3) on the front side of the flange portion (3a). It is arranged between the inner circumference. The spring (7) is a left-handed coil spring. The cross-sectional shape of the spring material constituting the spring (7) is a square having a relatively large front-rear width and radial thickness. As will be described in detail later, the rear end (one end) of the spring (7) is fixed to the shaft body (1), and the front end (other end) of the spring (7) is fixed to the pulley (3). .

  The pulley (3) is rotated clockwise as viewed from the front by a belt (not shown) applied to the pulley (3). The rotation of the pulley (3) is transmitted to the shaft body (1) via the coil spring (7), and the shaft body (1) also rotates in the same direction. During rotation, rotation fluctuation is absorbed by the coil spring (7), and the shaft (1) and the pulley (3) are allowed to rotate with each other by the bearings (5) and (6). 2 and 3, the rotation direction of the shaft body (1) and the pulley (3) is indicated by an arrow R.

  A first hook portion (7a) bent inward in the radial direction is formed at the rear end portion of the spring (7). The tip surface (7a1) of the first hook portion (7a) is a flat surface, and the inward surface (inward surface) (7a2) and the outward surface (outward surface) (7a3) are substantially arc-shaped curved surfaces. . A second hook portion (7b) bent outward in the radial direction is formed at the front end portion of the spring (7). The tip surface (7b1) of the second hook portion (7b) is a flat surface, and the inward surface (inward surface) (7b2) and the outward surface (outward surface) (7b3) are substantially arc-shaped curved surfaces. .

  On the outer periphery of the large-diameter portion (1b) of the shaft body (1), a first concave portion (10) for holding a spring into which the first hook portion (7a) of the spring (7) is fitted is formed. The bottom wall (10a) of the first recess (10) and the end wall (front end wall) (10b) on the front side in the rotation direction are flat surfaces, and the end wall (rear end wall) (10c) on the rear side in the rotation direction is the spring (7) The first hook portion (7a) has a curved surface similar to the inward surface (7a2). With the first hook portion (7a) fitted into the first recess (10), the inward surface (7a2) is in close contact with the rear end wall (10c) of the first recess (10), and the first recess (10) The bottom wall (10a) of the first hook portion (7a) and the front end surface (7a1) of the first hook portion (7a), and the front end wall (10b) of the first recess (10) and the outward surface (7a3) of the first hook portion (7a) In each case, gaps having a substantially triangular cross section are formed. A washer (11) and a first hook fixing bush (12) are fitted in order from the rear between the front end face of the flange (3a) of the pulley (3) and the rear end of the spring (7). The bush (12) is formed by integrally forming a cylindrical portion (12b) extending forward on the outer peripheral edge of the annular rear wall portion (12a). The rear wall (12a) is sandwiched between the washer (11) and the spring (7). The cylindrical portion (12b) is sandwiched between the inner periphery of the pulley (3) and the outer periphery of the spring (7), whereby the first hook portion (7a) is fixed in the first recess (10). Yes. The bush (12) is made of phosphor bronze, for example.

  On the inner periphery of the front end of the pulley (3), there is formed a spring retaining second recess (13) into which the second hook portion (7b) of the spring (7) is fitted. In this example, the second recess (13) reaches the outer periphery of the pulley (3). The end wall (front end wall) (13a) on the front side in the rotational direction of the second recess (13) is a curved surface similar to the outward surface (7b3) of the second hook part (7b), and the end wall on the rear side in the rotational direction (rear end wall) ) (13b) is a flat surface. With the second hook portion (7b) fitted into the second recess (13), the inward surface (7b2) of the second hook portion (7b) is the diameter of the rear end wall (13b) of the second recess (13). Close to the inner part of the direction. The front end of the spring (7) is sandwiched between the front inner periphery of the pulley (3) and the inner periphery of the large cylindrical portion (4c) front end side of the pulley cover (4). The second hook portion (7b) is fixed in the second recess (13). In this example, the inner cylindrical portion (4c) of the pulley cover (4) constitutes a second hook portion fixing cylindrical member.

  The front-rear width of the cylindrical portion (12b) of the bush (12) may be equal to or smaller than the front-rear width of the spring material constituting the spring (7), but in this example, it is smaller than the front-rear width of the spring material. The outer diameter of the spring material inside the cylindrical part (12b) of the bush (12) is smaller than the inner diameter of the pulley (3) by the thickness of the cylindrical part (12b). Greater than. By doing so, the outer diameter of the spring (7) can be increased as much as possible to increase the rigidity and the transmission torque. Since the spring material has a spiral shape, a portion of the rear end portion of the spring material inside the bush cylindrical portion (12b) is smaller than one round of the spring material. If the shape and dimensions of the spring (7) are constant, reducing the front-rear width of the bush cylindrical portion (12b) reduces the portion of the spring material inside the bush cylindrical portion (12b), but the bush cylindrical portion ( Since the strength of 12b) decreases, the dimensions of the bush cylindrical portion (12b) are determined in consideration of these.

  The bush (12) only needs to be a material having lubricity and a certain degree of strength, such as a material using a material other than phosphor bronze, for example, a steel bush added with a lubricating means such as a lubricant. May be.

  5 and 6 show a second embodiment.

  The configuration of the pulley unit of the second embodiment is the same as that of the first embodiment except for the bush (15), and the same parts are denoted by the same reference numerals.

  The bush (15) has an arc shape. The bush (15) has a cylindrical part (15b) integrally formed on the outer peripheral edge of the arcuate rear wall part (15a), and is further protruded radially inward at one end, in this example, at the front end in the rotational direction. (15c) is integrally formed. The tip surface (15c1) of the protrusion (15c) is a flat surface, and the radially inward surface (inward surface) (15c2) is the same as the outward surface (7a3) of the first hook portion (7a) of the coil spring (7) It is a curved surface. The bush (15) is made of, for example, a synthetic resin.

  The projecting portion (15c) is an outer surface (7a3) of the first hook portion (7a) of the coil spring (7) fitted in the first recess (10) of the shaft body (1) and the inner periphery of the pulley (3). The inwardly facing surface (15c2) of the projecting portion (15c) is overlapped along the outwardly facing surface (7a3) of the first hook portion (7a), and the tip surface (15c1) is the first recessed portion (10). The front end wall (10b) of the first recessed portion (10c) is in close contact with the front end wall (10b) of the first recessed portion (10) and the front end wall (10b) of the first recess (10) and the front end surface (7a1) of the first hook (7a). In this state, the first hook portion (7a) is fixed to the first concave portion (10).

  In this way, the protrusion (15c) of the bush (15) is sandwiched between the outward surface (7a3) of the first hook portion (7a) of the spring (7) and the inner peripheral surface of the pulley (3), The bush (15) is fixed to the first recess (10) of the shaft body (1) so that the bush (15) can be connected to the shaft body (1) and the spring even if the pulley (3) and the shaft body (1) rotate relative to each other. It rotates integrally with (7), and the first hook portion (7a) of the spring (7) is always fixed to the first recess (10).

  The size of the bushing arc is preferably 90 degrees or more and 180 degrees or less.

  In this case, since the bush (15) has an arc shape, the portion of the spring wire inside the bush cylindrical portion (15b) becomes small. For this reason, even if the longitudinal width of the bush cylindrical portion (15b) is increased, it is possible to increase the rigidity and transmission torque of the spring (7) by increasing the portion where the outer diameter of the spring wire is large. In addition, the spring wire is not constrained by the bush (15) around the entire circumference, and since the front and rear width of the bush cylindrical portion (15b) can be increased, the surface pressure acting on the bush (15) can be reduced, The bush (15) can be composed of a synthetic resin.

  The overall configuration of the pulley unit and the configuration of each unit are not limited to those of the above embodiment, and can be changed as appropriate.

  For example, in the above embodiment, the pulley (3) is composed of one component, but may be composed of two or more components. The same applies to other components.

(1) Shaft body
(3) Pulley
(4) Pulley cover
(4c) Inner cylindrical part
(5) (6) Bearing
(7) Torsion coil spring
(7a) First hook
(7b) Second hook
(12) First hook fixing bush
(10) First recess for holding spring
(13) Second recess for holding spring
(15) First hook fixing bush
(15c) Projection

Claims (2)

A shaft body in which a first recess for holding a spring is formed on the outer peripheral surface;
A pulley having a second recess for holding a spring formed on an inner peripheral surface, and rotatably supported by a bearing around the shaft body;
A first hook portion is disposed in an annular space between the shaft body and the pulley, and is bent radially inward at one end portion and fitted into the first recess for holding the spring, and radially outward at the other end portion. A coil spring formed with a second hook portion bent and fitted into the second recess for holding the spring;
A first hook fixing bush fitted between the outer periphery of the one end of the coil spring and the inner periphery of the pulley;
A pulley unit, comprising: a second hook portion fixing tubular member fixed to the pulley and fitted on an inner periphery of the other end portion of the coil spring.   The first hook fixing bush has an arcuate shape, and has a protrusion at one end thereof that overlaps the outer periphery of the one end of the coil spring and extends radially inward. The pulley unit according to claim 1, wherein the protrusion is sandwiched between the outer peripheral surface of the coil spring and the coil spring.

Images