JP2006200449A - Timing matching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce assembly man hour of a cam shaft drive mechanism by a matching mark such as a mark ring and an engraving provided on a power transmission element, reducing cost of a timing matching device facilitating work for installing power transmission element to each transmission wheel. <P>SOLUTION: A vehicle side matching mark 42 is formed on a crank sprocket 34 fixed on a crank shaft 13, an engine side matching mark 44 to which the vehicle side matching mark 42 is matched is formed on a crank case 12. A vehicle side matching mark 43 is formed on a cam sprocket 35 fixed on a cam shaft 26, an engine side matching mark 45 to which the vehicle side matching mark 43 is matched is formed on a cylinder head 17. Timing chain 36 is wound over each sprocket 34, 35 under a condition where position of each sprocket is matched based on the engine side by the matching marks 42-45. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a timing adjusting device used in a camshaft drive mechanism for transmitting rotation of a crankshaft to a camshaft, and in particular, a drive side transmission vehicle fixed to the crankshaft and a driven side transmission vehicle fixed to the camshaft. It is effective when applied to a device having a power transmission element that is stretched between the two.

  As a valve operating mechanism of a four-cycle engine having an intake valve and an exhaust valve, there is an OHC type in which an intake valve and an exhaust valve and a cam shaft for driving them are arranged in a cylinder head. In order to drive the mechanism, the engine is provided with a camshaft drive mechanism that transmits the rotation of the crankshaft attached to the crankcase to the camshaft. As the camshaft drive mechanism, a chain drive type having a timing chain spanned between a sprocket fixed to the crankshaft and a sprocket fixed to the camshaft as a power transmission element, a pulley and a cam fixed to the crankshaft There is a belt drive type equipped with a timing belt (toothed belt) spanned by a pulley fixed to the shaft as a power transmission element. In either type, the rotation of the crankshaft is transferred to the camshaft via a timing chain etc. Communicated.

  In an engine equipped with such a camshaft drive mechanism, in order to operate the intake / exhaust valve at a predetermined timing with respect to the reciprocating motion of the piston connected to the crankshaft, a timing chain is attached to each sprocket or a timing belt. Must be matched to each pulley when the phase of the crankshaft and the phase of the camshaft are matched.

In Patent Literature 1, alignment marks are engraved on each of the sprocket fixed to the crankshaft, the sprocket fixed to the camshaft, and the timing chain (silent chain), and the alignment mark of the timing chain is aligned with the alignment mark of each sprocket. A technique is disclosed in which the phases of the crankshaft and the camshaft are matched by mounting in this manner. Further, in Patent Document 2, a rotation phase instruction mark for instructing the rotation phase of the cam shaft is provided on the side surface of the pulley fixed to the cam shaft, and a meshing instruction mark is provided on the side surface of the timing belt to engage with the rotation phase instruction mark. A technique is disclosed in which the timing belt is stretched over a pulley so as to be aligned with the indication mark, and the phase of the crankshaft and the camshaft is adjusted by matching the rotation phase indication mark with the alignment mark provided on the cylinder head cover. . Furthermore, in Patent Document 3, a pair of through holes are formed on both sides of the camshaft shaft center of the sprocket fixed to the camshaft, and the upper surface of the cylinder head is simultaneously visually confirmed through these throughholes. Thus, a technique is disclosed in which the phases of the crankshaft and the camshaft are matched.
Japanese Patent Laid-Open No. 11-13841 Japanese Utility Model Publication No. 1-102407 Japanese Utility Model Publication No. 5-14567

  However, as described in Patent Documents 1 and 2, the timing of the crankshaft and the camshaft are synchronized by adjusting the meshing position of the timing chain and timing belt with respect to the sprocket and pulley. It is necessary to provide a mark link with a special identification color on the chain, or to engrave or paint a predetermined position, which increases the cost. In addition, when the timing chain or the timing belt is passed over the sprocket or pulley, it is necessary to search for a mark link or a stamp, which increases the number of steps for assembling the camshaft drive mechanism.

  On the other hand, as shown in Patent Document 3, if a pair of through holes are provided in the sprocket, a drilling process for forming these through holes is required when manufacturing the sprocket, and the cost of the sprocket is reduced accordingly. Get higher.

  An object of the present invention is to eliminate the need for alignment marks such as mark links and engravings provided on the power transmission element, and to reduce the cost of the timing adjusting device.

  Another object of the present invention is to facilitate the mounting operation of the power transmission element to each transmission vehicle and reduce the number of assembling steps of the camshaft drive mechanism.

  The timing adjustment device of the present invention is a timing adjustment device used in a camshaft drive mechanism having a power transmission element that is stretched between a drive-side transmission vehicle fixed to a crankshaft and a driven-side transmission vehicle fixed to a camshaft. A cylinder head in which a vehicle side alignment mark is formed on the driving side transmission vehicle and the driven side transmission vehicle, and the crankshaft is rotatably mounted and the camshaft is rotatably mounted. An engine side mark is formed on the crankcase, and the vehicle side mark of the drive side transmission vehicle is aligned with the engine side mark of the crankcase, and the vehicle side side of the driven side transmission vehicle is aligned with the engine side mark of the cylinder head. The power transmission element is spanned between the drive-side transmission vehicle and the driven-side transmission vehicle in a state where the marks are aligned.

  The timing adjustment device according to the present invention includes a groove-shaped vehicle side alignment mark formed on the drive side transmission vehicle and the driven side transmission vehicle formed by sintering, and the crankcase and the cylinder head formed by casting. The engine-facing mark having a convex shape or a concave shape is formed.

  In the timing adjusting apparatus according to the present invention, the power transmission element is a timing chain, and the driving side transmission vehicle and the driven side transmission vehicle are sprockets.

  According to the present invention, by adjusting the phase of the drive side transmission vehicle with the crankcase as a reference and adjusting the phase of the driven side transmission vehicle with the cylinder head as a reference, the power transmission element with respect to each transmission vehicle is engaged regardless of the meshing position. Since the phases of the crankshaft and camshaft can be adjusted, it is not necessary to provide the power transmission element with mark links, engraving marks, or paint marks for indicating the meshing position with each transmission vehicle. Cost can be reduced. In addition, there is no need to look for mark marks or engraved marks such as engraved marks when the power transmission elements are passed over to each transmission vehicle, making it easy to mount the power transmission elements on each transmission vehicle and the camshaft drive mechanism. Assembling man-hours can be reduced.

  In addition, according to the present invention, when the transmission wheels are formed by sintering, the vehicle side marks can be formed simultaneously, and when the crankcase and the cylinder head are formed by casting, the engine side marks are formed simultaneously. Therefore, the process for forming the alignment mark is not required, and the cost of the timing alignment apparatus can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a general-purpose engine equipped with a timing adjusting apparatus according to an embodiment of the present invention. The general-purpose engine 11 is a single-cylinder four-cycle gasoline engine, for example, the power of a generator or a compressor. Used as a source etc.

  As shown in FIG. 1, the general-purpose engine 11 has a crankcase 12 formed by casting, and a crankshaft 13 is rotatably mounted on the crankcase 12. The crankcase 12 has a partition wall 12a, and the crankshaft 13 is supported by a bearing (not shown) provided on the partition wall 12a and is rotatable. A cylinder 14 formed by casting is assembled on the upper side of the crankcase 12, and a piston 15 is mounted in a cylinder bore 14 a formed in the cylinder 14 so as to be capable of reciprocating. The piston 15 is connected to the crankpin 13a of the crankshaft 13 through a connecting rod 16, and the crankshaft 13 is rotationally driven by the reciprocating motion of the piston 15. Lubricating oil L is stored in the crankcase 12, and when the crankshaft 13 rotates, the lubricating oil L is scraped up by a connecting rod 16 or a scraper (not shown) provided on the crankshaft 13, and a sliding portion such as the crankshaft 13 or the like. Lubrication and cooling of the high temperature part such as the cylinder 14 are performed.

  A cylinder head 17 formed by low pressure casting is attached to the upper side of the cylinder 14, and the engine body is formed by the crankcase 12, the cylinder 14, and the cylinder head 17. A combustion chamber 18 is formed between the piston 15 and the cylinder head 17, and an intake port 21 that supplies an air-fuel mixture to the combustion chamber 18 and an exhaust port 22 that discharges combustion exhaust gas in the combustion chamber 18 are cylinder head 17. Is formed. A plurality of radiating fins 23 are provided on the outer walls of the cylinder 14 and the cylinder head 17 so as to protrude outward, and the heat in the combustion chamber 18 is passed through the cylinder 14 and the cylinder head 17 by these radiating fins 23. Released to the outside. An ignition plug (not shown) for igniting the air-fuel mixture supplied into the combustion chamber 18 is attached to the cylinder head 17.

  The cylinder head 17 is provided with an intake valve that opens and closes the intake port 21, that is, an intake valve 24, and an exhaust valve that opens and closes the exhaust port 22, that is, an exhaust valve 25. The cylinder head 17 is driven to open and close these valves 24 and 25. A camshaft 26 having a valve cam 26a is rotatably mounted. The cylinder head 17 is provided with a rocker shaft 27 in parallel with the cam shaft 26, and a rocker arm 28 that opens and closes the intake valve 24 and a rocker that opens and closes the exhaust valve 25 at a predetermined timing by the rotation of the valve cam 26a. An arm 29 is swingably attached to the rocker shaft 27. The valves 24 and 25 are urged in the closing direction by a valve spring 31. When the cam shaft 26 rotates, the rocker arms 28 and 29 swing along the shape of the valve cam 26a. The intake valve 24 and the exhaust valve 25 are opened and closed against this. As described above, the valve operating mechanism for opening and closing the intake valve 24 and the exhaust valve 25 is an OHC type in which the cam shaft 26 and the rocker arms 28 and 29 are mounted on the cylinder head 17.

  A rocker cover 32 made of sheet metal or synthetic resin is attached to the upper side of the cylinder head 17, and the valve operating mechanism is covered with the rocker cover 32.

  FIG. 2 is a cross-sectional view showing a cam shaft drive mechanism for driving the cam shaft shown in FIG. In order to drive the mechanism, a camshaft drive mechanism 33 is provided.

  As shown in FIG. 2, the camshaft drive mechanism 33 is connected to a crank sprocket 34 as a drive-side transmission vehicle fixed to the end of the crankshaft 13 protruding from the partition wall 12 a of the crankcase 12, and to the end of the camshaft 26. It has a cam sprocket 35 as a driven-side transmission wheel that is fixed, and in the present embodiment, these sprockets 34 and 35 are formed by sintering. A timing chain 36 as a power transmission element for transmitting the power of the crankshaft 13 to the camshaft 26 is stretched between the crank sprocket 34 and the cam sprocket 35, and when the crankshaft 13 rotates, the power is transmitted via the timing chain 36. It is transmitted to the cam shaft 26, and the cam shaft 26 is rotationally driven. The cam sprocket 35 has twice as many teeth as the crank sprocket 34. When the crankshaft 13 makes two revolutions, the camshaft 26 makes one revolution, whereby the intake valve is synchronized with a predetermined timing synchronized with the reciprocating motion of the piston 15. 24 and the exhaust valve 25 are driven. Thus, the camshaft drive mechanism 33 is comprised by the crank sprocket 34, the cam sprocket 35, and the timing chain 36, that is, the camshaft drive mechanism 33 is a chain drive type.

  When the crankshaft 13 rotates in the direction of arrow A in FIG. 2, the portion of the timing chain 36 that travels from the cam sprocket 35 toward the crank sprocket 34 becomes the tight side 36 a, and the crank sprocket 34 of the timing chain 36 moves from the cam sprocket 35 to the cam sprocket 35. The portion that travels toward becomes the loose side 36b. In order to hold the travel line on the tension side 36a of the timing chain 36, a resin chain guide 37 that contacts the tension side 36a of the timing chain 36 is fixed to the cylinder 14 to prevent the timing chain 36 from loosening. A tensioner lever 38 that urges the loose side 36b of the timing chain 36 toward the tension side 36a is swingably attached to the cylinder 14.

  FIG. 3 is a perspective view showing details of the alignment mark on the crank sprocket side, and FIG. 4 is a perspective view showing details of the alignment mark on the cam sprocket side.

  The camshaft drive mechanism 33 sets the phase of the crankshaft 13 and the camshaft 26 to a predetermined level when the timing chain 36 is passed over the crank sprocket 34 and the cam sprocket 35 during assembly or maintenance of the general-purpose engine 11. In order to match the timing, a timing adjusting device 41 is provided. As shown in FIGS. 3 and 4, the timing adjusting device 41 includes vehicle side alignment marks 42 and 43 formed on the crank sprocket 34 and the cam sprocket 35, and an engine side formed on the crankcase 12 and the cylinder head 17. It is composed of counter marks 44 and 45.

  As shown in FIG. 3, the vehicle side alignment mark 42 provided on the crank sprocket 34 is formed in a groove shape extending in the radial direction on the side surface of the crank sprocket 34, and is similarly provided on the vehicle side provided on the cam sprocket 35. As shown in FIG. 4, the alignment mark 43 is formed in a groove shape extending in the radial direction on the side surface of the cam sprocket 35. The vehicle side alignment mark 42 is formed simultaneously when the crank sprocket 34 is formed by sintering, and the vehicle side alignment mark 43 is formed simultaneously when the cam sprocket 35 is formed by sintering. A post-process for forming the vehicle side marks 42 and 43 is not necessary. That is, grooves corresponding to the vehicle facing marks 42 and 43 are formed when a material such as metal powder is pressure-formed into the shape of the crank sprocket 34 or the cam sprocket 35 in the pre-process of the sintering process. Vehicle side alignment marks 42 and 43 are simultaneously formed on the side surfaces of the sintered sprockets 34 and 35. Accordingly, the vehicle side alignment marks 42 and 43 can be formed on the respective sprockets 34 and 35 in the sintering stage, and a post-process for forming these vehicle side alignment marks 42 and 43 is not required, and this timing adjustment device 41 is provided. The cost can be reduced.

  On the other hand, as shown in FIG. 3, the engine side mark 44 provided on the crankcase 12 has a convex shape that extends in the radial direction of the crank sprocket 34 and protrudes in the axial direction of the crankshaft 13 in the partition wall 12 a of the crankcase 12. The engine side mark 45 formed on the cylinder head 17 is formed in a concave shape extending in the axial direction of the cam shaft 26 on the upper surface of the cylinder head 17. The engine side mark 44 is formed at the same time when the crankcase 12 is cast, and the engine side mark 45 is formed at the same time when the cylinder head 17 is cast at low pressure to form the engine side marks 44 and 45. The subsequent process is unnecessary. That is, grooves or protrusions corresponding to the engine facing marks 44 and 45 are formed in advance in a mold for casting the crankcase 12 or the cylinder head 17, so that the cast crankcase 12 or the cylinder head 17 is simultaneously formed. Engine side marks 44 and 45 are formed. Therefore, the engine side marks 44 and 45 can be formed on the crankcase 12 or the cylinder head 17 in the casting stage, and a post-process for forming these engine side marks 44 and 45 is not required, and the timing adjusting device 41 can Cost can be reduced.

  FIG. 5 is a front view showing a state where the crank sprocket is aligned, and FIG. 6 is a front view showing a state where the cam sprocket is aligned.

  Next, a timing adjustment method of the camshaft drive mechanism 33 using the timing adjustment device 41 having such a configuration will be described with reference to FIGS.

  First, as shown in FIG. 5, before the timing chain 36 is passed, the crank sprocket 34 is rotated so that the vehicle side mark 42 of the crank sprocket 34 is aligned with the engine side mark 44 of the crankcase 12. Thereby, the crankshaft 13 is adjusted to a predetermined phase (in the illustrated case, the position where the piston 15 is the compression top dead center). At this time, a cover (not shown) covering the crank sprocket 34 of the crankcase 12 is removed.

  Next, as shown in FIG. 6, the rocker cover 32 is removed from the cylinder head 17 and the cam sprocket 35 is rotated to align the vehicle side mark 43 of the cam sprocket 35 with the engine side mark 45 of the cylinder head 17. Thereby, the camshaft 26 is adjusted to a phase corresponding to the phase of the crankshaft 13 adjusted to a predetermined phase by the above-described operation.

  In this state, the timing chain 36 is passed over the crank sprocket 34 and the cam sprocket 35. At this time, first, the timing chain 36 is stretched over only one of the crank sprocket 34 and the cam sprocket 35, and tension is applied to the timing chain 36 to bring the tension side into contact with the chain guide 37. Next, the tensioner lever 38 is pushed to the open side so that the timing chain 36 is loosened, and the timing chain 36 is passed over either the crank sprocket 34 or the cam sprocket 35. Thereby, the phases of the crank sprocket 34 and the cam sprocket 35 are matched, and the tension side of the timing chain 36 is set to a predetermined length, so that the phases of the crankshaft 13 and the camshaft 26 after the timing chain 36 is mounted can be synchronized.

  As described above, in the timing adjusting device 41, the sprockets 34, 35 are set with reference to the engine body side such as the crankcase 12 and the cylinder head 17 without matching the meshing positions of the timing chains 36 with the sprockets 34, 35. Since the phases of the crankshaft 13 and the camshaft 26 can be matched by aligning the rotational positions of the shafts, mark links, engravings, and paint marks for indicating the meshing positions of the sprockets 34 and 35 to the timing chain 36 are provided. Since it is not necessary to provide the timing adjusting device 41, the cost of the timing adjusting device 41 can be reduced. Further, when the timing chain 36 is passed over the sprockets 34 and 35, it is not necessary to search for a matching mark such as a mark link or engraving, so that the timing chain 36 can be easily attached and the camshaft drive mechanism 33 can be assembled. Man-hours can be reduced.

  Further, when the sprockets 34 and 35 are formed by sintering, the vehicle side alignment marks 42 and 43 can be formed simultaneously, and when the crankcase 12 and the cylinder head 17 are formed by casting, the engine side alignment marks are formed. Since 44 and 45 can be formed simultaneously, the post-process for forming the alignment mark is not required, and the cost of the timing alignment device 41 can be reduced.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the present embodiment, the timing chain 36 is used as a power transmission element. However, the present invention is not limited to this, and a timing belt (toothed belt) may be used. In this case, pulleys are attached to the crankshaft 13 and the camshaft 26 as transmission wheels.

  In the present embodiment, the vehicle side marks 42 and 43 are formed on the side surfaces of the sprockets 34 and 35, and the engine side marks 44 and 45 are formed on the partition wall 12 a of the crankcase 12 and the upper surface of the cylinder head 17. However, the present invention is not limited to this, and the position where these alignment marks are formed is not limited as long as the rotational positions of the sprockets 34 and 35 can be aligned with reference to the crankcase 12 and the cylinder head 17.

  Further, in the present embodiment, the vehicle-side alignment marks 42, 43 are formed in a groove shape, and the engine-side alignment marks 44, 45 are formed in a convex shape or a concave shape. If the rotation position of 35 can be aligned with reference to the crankcase 12 and the cylinder head 17, the shape is not limited.

  Furthermore, in the present embodiment, the sprockets 34 and 35 are formed by sintering, and the crankcase 12 and the cylinder head 17 are formed by casting. However, the present invention is not limited to this, and the sprockets 34 and 35 are formed by other manufacturing methods. May be.

It is sectional drawing which shows the general purpose engine provided with the timing alignment apparatus which is one embodiment of this invention. It is sectional drawing which shows the cam shaft drive mechanism for driving the cam shaft shown in FIG. It is a perspective view which shows the detail of the alignment mark by the side of a crank sprocket. It is a perspective view which shows the detail of the alignment mark by the side of a cam sprocket. It is a front view which shows the state which aligned the crank sprocket. It is a front view which shows the state which aligned the cam sprocket.

Explanation of symbols

11 General-purpose engine 12 Crankcase 13 Crankshaft 17 Cylinder head 26 Camshaft 33 Camshaft drive mechanism 34 Crank sprocket (drive-side transmission vehicle)
35 Cam sprocket (driven gear)
36 Timing chain (power transmission element)
41 Timing adjustment device 42, 43 Car side alignment mark 44, 45 Engine side alignment mark

Claims (3)

A timing adjusting device used in a camshaft drive mechanism including a power transmission element that is spanned between a drive-side transmission vehicle fixed to a crankshaft and a driven-side transmission vehicle fixed to a camshaft,
A vehicle side alignment mark is formed on the driving side transmission vehicle and the driven side transmission vehicle,
An engine side mark is formed on a crankcase on which the crankshaft is rotatably mounted and a cylinder head on which the camshaft is rotatably mounted;
The vehicle side alignment mark of the drive side transmission vehicle is aligned with the engine side alignment mark of the crankcase and the vehicle side alignment mark of the driven side transmission vehicle is aligned with the engine side alignment mark of the cylinder head. A timing adjusting device, wherein the power transmission element is stretched between a driving side transmission vehicle and the driven side transmission vehicle.   2. The timing adjustment device according to claim 1, wherein the drive-side transmission vehicle and the driven-side transmission vehicle formed by sintering are formed with groove-shaped vehicle-side alignment marks, and the crankcase formed by casting and A timing adjustment apparatus, wherein the engine side mark having a convex shape or a concave shape is formed on a cylinder head.   3. The timing adjusting device according to claim 1, wherein the power transmission element is a timing chain, and the driving transmission vehicle and the driven transmission vehicle are sprockets.

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