JP2006132559A - Belt pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt pulley with flange plates at both ends reduced in cost. <P>SOLUTION: At one end of a pulley body 35, a plurality of first flange plates 40 are formed which are protruded outward in the radial direction. At the other end of the pulley body 35, a plurality of second flange plates 41 are formed which are protruded outward in the radial direction. The flange plates 40, 41 are spaced from each other side by side in the peripheral direction and shifted to each other in the peripheral direction not to face each other. Since the flange plates 40, 41 protruded outward in the radial direction are formed not to face each other, a cam pulley 12 can be integrally formed with the flange plates 40, 41 at both ends, which are not arranged in the pull-off direction of a mold to be pulled off after pressure molding. Thus, the cam pulley 12 is reduced in cost with less numbers of components and machining man-hours. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a belt pulley around which a toothed belt is wound.

  As a transmission mechanism for transmitting power from one rotary shaft to the other rotary shaft, there is a belt transmission mechanism in which a belt is wound between pulleys attached to each rotary shaft. As a transmission system of the belt transmission mechanism, there are a simple friction system and a high-precision meshing system, a flat belt or a V belt is used for the friction system, and a toothed belt is used for the meshing system. .

  A meshing type belt transmission mechanism using a toothed belt is often employed, for example, in a valve operating mechanism of a four-cycle engine. The engine valve mechanism has a camshaft that opens and closes the intake and exhaust valves, and rotates from the crankshaft to the camshaft to open and close the intake and exhaust valves at a predetermined timing in synchronization with the crank angle as the engine rotates. Therefore, a timing belt, which is a toothed belt, is stretched between a crank pulley fixed to the crankshaft and a cam pulley fixed to the camshaft.

  While the rotation of the crankshaft is linked to the reciprocating movement of the piston, the rotation of the camshaft is linked to the reciprocating movement of the intake valve and the exhaust valve, and keeps the engine operating normally by avoiding interference between the piston and the valve. For this purpose, it is necessary to accurately synchronize the camshaft and the crankshaft while maintaining good timing belt engagement. For this reason, the engine is equipped with a tension pulley that properly holds the belt tension of the timing belt.Furthermore, in order to reliably prevent the timing belt from skipping, flange plates are provided at both ends of the crank pulley and cam pulley. (For example, refer to Patent Document 1).

By the way, in the manufacturing process of the crank pulley and the cam pulley, a die is often used to reduce the manufacturing cost. As described above, as a molding method using a mold, injection molding (for example, refer to Patent Document 1) in which a resin pulley is molded by injecting a heat-melted resin material into the mold, or a metal material is used. Press molding (for example, refer to Patent Document 2) that molds a metal pulley by punching with a mold, or press-molding a metal powder enclosed in a mold, and then heating the molded metal to form powder particles There is a method of manufacturing a sintered pulley by diffusion bonding (sintering) and the like.
Japanese Utility Model Publication No. 6-73522 JP 2004-160479 A

  However, when forming a crank pulley or cam pulley using a mold, the shape of the product is restricted because it is necessary to pull out the mold after molding, and flange plates are attached to both ends of the crank pulley and cam pulley. It was impossible to mold. For this reason, as shown in Patent Document 1, when providing flange plates at both ends of the crank pulley and cam pulley, it is necessary to form one flange plate separately and assemble the flange plate to the pulley body. In such a manufacturing method, it is difficult to reduce the manufacturing cost because the number of parts and the number of processing steps are increased.

  An object of the present invention is to achieve cost reduction of a belt pulley having flange plates at both ends.

  The belt pulley of the present invention is a belt pulley around which a toothed belt is wound, and a pulley main body in which a plurality of teeth meshing with the toothed belt are formed on an outer peripheral surface, and a radially outer side at one end of the pulley main body. A plurality of first flange plates that are formed to protrude in the circumferential direction and arranged at intervals in the circumferential direction, and are formed to project radially outward from the other end portion of the pulley body, and are arranged at intervals in the circumferential direction. The first flange plate and the second flange plate are arranged so as to be shifted in the circumferential direction without facing each other.

  The belt pulley according to the present invention is characterized in that the pulley body, the first flange plate, and the second flange plate are integrally formed.

  According to the present invention, the first flange plate formed at one end of the pulley body and the second flange plate formed at the other end of the pulley body are shifted in the circumferential direction without facing each other. Since it was made to do, it becomes possible to integrally mold a belt pulley provided with a flange plate at both ends. Thereby, the number of parts and the number of processing steps can be reduced, and the cost reduction of the belt pulley can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view showing a four-cycle engine 11 (hereinafter referred to as an engine) provided with a valve operating mechanism 10. The engine 11 includes a cam pulley 12 and a crank pulley as a belt pulley according to an embodiment of the present invention. 13 is attached. The illustrated engine 11 is a general-purpose engine used as a power source for a generator or a compressor.

  As shown in FIG. 1, the engine 11 includes a crankcase 15 that rotatably accommodates a crankshaft 14 and a cylinder 16 that reciprocally accommodates a piston (not shown). Are integrally formed to form a cylinder block 17. A cylinder head 18 that houses the valve mechanism 10 is assembled to the upper end surface of the cylinder 16, and a head cover 19 is assembled to the upper end surface of the cylinder head 18.

  The valve mechanism 10 includes a camshaft 20 that is incorporated in parallel with the crankshaft 14 and an intake valve 21 that is incorporated in the cylinder head 18 so as to be openable and closable, and between the camshaft 20 and the intake valve 21. An intake rocker arm 22 that converts the rotational motion of the cam 20a provided on the cam shaft 20 into reciprocating motion is incorporated. Similarly, an exhaust valve 23 is incorporated in the cylinder head 18 so as to be openable and closable, and an exhaust rocker arm 24 for converting the rotational motion of the cam 20b into a reciprocating motion is provided between the cam shaft 20 and the exhaust valve 23. It has been incorporated. That is, by rotating the camshaft 20 and swinging the rocker arms 22 and 24, the intake valve 21 and the exhaust valve 23 are opened and closed at a predetermined timing. The intake valve 21 and the exhaust valve 23 are urged in the closing direction by valve springs 25 and 26.

  Such a camshaft 20 is driven by engine power output from the crankshaft 14. Therefore, a cam pulley 12 is attached to the end of the camshaft 20, a crank pulley 13 is attached to the end of the crankshaft 14, and a toothed belt is provided between the cam pulley 12 and the crank pulley 13. The timing belt 30 is stretched over. The teeth formed on the timing belt 30 and the teeth formed on the outer peripheral surfaces of the cam pulley 12 and the crank pulley 13 are engaged with each other, so that the crankshaft 14 and the camshaft 20 do not cause the timing belt 30 to slip. Can be accurately synchronized with each other, and the operating state of the engine 11 can be kept normal. As shown in FIG. 1, a tension pulley 31 is attached to the cylinder 16. By applying a predetermined belt tension to the timing belt 30, tooth skipping and loosening of the timing belt 30 are prevented. The timing belt 30 is formed by using a core material made of a cord such as fiber or steel and a rubber material covering the core material.

  2A is a side view showing the cam pulley 12, and FIG. 2B is a plan view showing the cam pulley 12 from the direction of arrow a. 3A is a perspective view showing the cam pulley 12 as a single unit, and FIG. 3B is a perspective view showing the cam pulley 12 with the timing belt 30 wound thereon. Subsequently, the shape of the cam pulley 12 will be described with reference to FIGS. 2 and 3.

  As shown in FIGS. 2 and 3, the pulley body 35 constituting the cam pulley 12 includes a hub portion 36 and a rim portion 37, and an insertion hole 38 into which the cam shaft 20 is inserted in the center portion of the hub portion 36. A plurality of teeth 39 that mesh with the teeth 32 of the timing belt 30 are formed on the outer peripheral surface of the rim portion 37. A plurality of first flange plates 40 (hereinafter referred to as flange plates) projecting radially outward are formed at one end of the rim portion 37, and radially outward at the other end of the rim portion 37. A plurality of protruding second flange plates 41 (hereinafter referred to as flange plates) are formed. The flange plates 40 and 41 are formed so as to be arranged at intervals in the circumferential direction, and are shifted in the circumferential direction without facing each other. A key groove 42 is formed in the insertion hole 38 of the hub portion 36, and the cam pulley 12 is fixed to the cam shaft 20 in the circumferential direction by inserting a key (not shown) into the key groove 42. become.

  Thus, by forming the flange plates 40 and 41 at one end and the other end of the pulley body 35, the timing belt 30 is moved in the width direction by the flange plates 40 and 41 as shown in FIG. Since it can be held, the timing belt 30 can be prevented from falling off. Further, since the flange plates 40 and 41 are formed so as to protrude radially outward from the tooth tip surfaces of the teeth 39 formed on the cam pulley 12, the flange plates 40 and 41 are reliably brought into contact with the side surfaces of the timing belt 30. Therefore, the deviation of the timing belt 30 can be reliably suppressed.

  Then, the manufacturing method of the cam pulley 12 is demonstrated. First, the illustrated cam pulley 12 is manufactured by encapsulating metal powder in a mold and press-molding it, and then heat-molding the metal to diffuse-bond (sinter) the powder particles. Yes. Here, FIG. 4A is a schematic view showing a press machine 45 that press-molds the cam pulley 12, and FIG. 4B is a hatched working surface formed by one of the punches incorporated in the press machine 45. It is a perspective view of the cam pulley 12 shown. In FIG. 4B, only the processed surface formed on the rim portion 37 is shown by hatching.

  As shown in FIG. 4A, a press machine 45 for press-molding the cam pulley 12 is slidably accommodated in a die 46 having a circular sliding hole 46a and the sliding hole 46a of the die 46. An upper punch 47 and a lower punch 48 are provided. When performing pressure molding, the metal powder is sandwiched between the upper punch 47 and the lower punch 48 by moving the upper punch 47 downward while the metal powder is sealed in the sliding hole 46a. Thus, the cam pulley 12 is processed. After press molding, the processed cam pulley 12 is removed from the die 46 by moving the upper punch 47 up and then moving the lower punch 48 up.

  Here, as shown in FIG. 3A, the flange plates 40 and 41 formed at both ends of the cam pulley 12 are formed so as to be shifted in the circumferential direction without facing each other. The cam pulley 12 having the flange plates 40 and 41 can be integrally formed with the main body 35. That is, as shown in FIGS. 4A and 4B, since the flange plates 40 and 41 do not overlap in the axial direction, the pull-out movement of the punches 47 and 48 after molding is obstructed by the flange plates 40 and 41. The cam pulley 12 having the flange plates 40 and 41 at both ends can be integrally formed. Thereby, the number of parts and the number of processing steps can be reduced, and the cost reduction of the cam pulley 12 can be achieved.

  In the above description, the cam pulley 12 has been mainly described. However, even in the crank pulley 13 attached to the crankshaft 14, as shown in FIG. 1, flange plates shifted in the circumferential direction without facing each other are used. It is provided at both ends, and the crank pulley 13 can be integrally formed using a mold.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, the belt pulley is not limited to the cam pulley 12 or the crank pulley 13 applied to the engine 11, and the present invention may be applied to a toothed pulley applied to office equipment such as a copying machine or a printer. .

  Further, in the illustrated case, the flange plates 40 and 41 are formed substantially at right angles to the tooth tip surface. However, the shape is not limited to this, and the flange plates 40 and 41 are arranged with respect to the tooth tip surface. You may make it incline. Further, the width dimension of the flange plates 40 and 41 formed on the cam pulley 12 is set so as to overlap three teeth, but is not limited to this width dimension, the number of teeth of the cam pulley 12, the pulley diameter, and the like. You may change according to.

  Furthermore, the material for molding the cam pulley 12 and the crank pulley 13 is not limited to sintered metal. When the load is small, the cam pulley 12 and the crank pulley 13 are injection molded using a resin material. Also good. Furthermore, it goes without saying that a metal material may be formed on the cam pulley 12 or the crank pulley 13 by forging or casting. In any processing method, the cam pulley 12 and the crank pulley 13 having the flange plates 40 and 41 at both ends are integrally formed by providing the flange plates 40 and 41 so as to be shifted in the circumferential direction without facing each other. It becomes possible. Thereby, the number of parts and the number of processing steps can be reduced, and the cost reduction of the cam pulley 12 and the crank pulley 13 can be achieved.

  Note that when the cam pulley 12 and the crank pulley 13 are pressure-molded, there is no limitation to the one-pressing method in which only the upper punch 47 is lowered and pressed, and the upper punch 47 and the lower punch 48 are moved and added. A double pressing method for pressing, a floating die method for holding the die 46 movably up and down, or a pulling down method for lowering the die 46 in accordance with the downward movement of the upper punch 47 may be used.

It is a side view which shows the engine provided with the valve operating mechanism. (A) is a side view showing a cam pulley, and (B) is a plan view showing the cam pulley from the direction of arrow a. (A) is a perspective view showing a cam pulley as a single unit, and (B) is a perspective view showing the cam pulley in a state where a timing belt is wound. (A) is the schematic which shows the press machine which press-molds a cam pulley, (B) is a perspective view of the cam pulley which shows the process surface shape | molded by one of the punches integrated in a press machine by hatching.

Explanation of symbols

12 Cam pulley (belt pulley)
13 Crank pulley (belt pulley)
30 Timing belt (toothed belt)
35 Pulley body 40 Flange plate (first flange plate)
41 Flange plate (2nd flange plate)

Claims (2)

A belt pulley around which a toothed belt is wound;
A pulley body in which a plurality of teeth meshing with the toothed belt are formed on the outer peripheral surface;
A plurality of first flange plates formed at one end of the pulley body so as to protrude radially outward and arranged at intervals in the circumferential direction;
A plurality of second flange plates formed on the other end portion of the pulley body so as to protrude radially outward and arranged at intervals in the circumferential direction;
The belt pulley, wherein the first flange plate and the second flange plate are arranged so as to be shifted in the circumferential direction without facing each other.   The belt pulley according to claim 1, wherein the pulley body, the first flange plate, and the second flange plate are integrally formed.

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