JP2006226215A - Lubricating device of ohc type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the lubricating performance of a valve gear cam in an OHC type engine. <P>SOLUTION: A camshaft 33 opening and closing an intake valve and an exhaust valve is installed in a cylinder head, and a driven side pulley 36 from which a timing belt 37 is stretched to a drive side pulley fixed to a crankshaft is fixed to the camshaft 33. A plurality of tooth grooves 72 engaged with the teeth 37a of the timing belt 37 are peripherally formed, parallel with each other, on the outer peripheral part of the driven side pulley 37, and these tooth grooves 72 are held by a pair of flange parts 36c. A through hole 74 passed to the valve gear cam 34 is formed in each of the tooth grooves 72. A lubricating oil L adhered to the timing belt 37 is fed from the tooth grooves 72 to the valve gear cam 34 through the through holes 74. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lubrication device for an OHC engine in which a camshaft for opening and closing an intake valve and an exhaust valve is provided in a cylinder head.

  An OHC (Over Head Camshaft) type engine is a type of engine in which a camshaft for opening and closing an intake valve and an exhaust valve is provided in a cylinder head. The drive of the camshaft is driven by a drive pulley fixed to the crankshaft and a camshaft. This is done via a timing pulley that is stretched over a driven pulley that is fixed.

  In such an OHC type engine, the lower end of the crankcase to which the crankshaft is mounted is an oil pan that contains lubricating oil, and the lubricating oil in the oil pan is provided by a repellent or the like attached to the crankshaft. It is repelled in the case and supplied to sliding surfaces such as a bearing that rotatably supports the crankshaft and a journal portion of the crankshaft.

However, depending on the repellent tool attached to the crankshaft, it is difficult to supply the lubricating oil directly to the valve cam provided on the cylinder head distant from the crankshaft. Therefore, in the OHC type engine described in Patent Document 1, a guide wall is provided in the crankcase, and the lubricating oil repelled by the impeller is guided to the valve cam by this guide wall.
JP-A-10-141037

  However, as described in Patent Document 1, it is difficult to supply a sufficient amount of lubricating oil to the valve cam in the structure in which the lubricating oil splashed into the crankcase is guided to the valve cam by the guide wall. . In particular, in the case of a vertical type engine in which the crankshaft and camshaft are arranged in the vertical direction, the camshaft is arranged in the horizontal direction with respect to the oil pan, so that the lubrication scattered by the repellent tool It has been difficult to sufficiently supply oil to the valve cam.

  An object of the present invention is to improve the lubrication performance of a valve cam in an OHC type engine.

  The lubrication device for an OHC type engine of the present invention is a lubrication device for an OHC type engine in which a camshaft for opening and closing an intake valve and an exhaust valve is provided in a cylinder head, and between a drive pulley fixed to a crankshaft. The driven pulley on which the timing belt is stretched is fixed to the camshaft, and a through-hole that penetrates toward the valve cam of the camshaft is formed in the tooth groove engaged with the timing belt of the driven pulley. The lubricating oil attached to the timing belt is supplied to the valve cam through the through hole.

  The lubrication device for an OHC engine according to the present invention is characterized in that the crankshaft is mounted on the crankcase so as to face in the vertical direction.

  The lubrication device for an OHC engine according to the present invention is characterized in that a pair of flange portions sandwiching the tooth gap are provided on the driven pulley.

  According to the present invention, the lubricating oil adhering to the timing belt can be supplied to the valve cam, so that the lubrication performance of the valve cam and valve mechanism in the OHC engine can be improved.

  Further, according to the present invention, the valve cam can be constructed with a simple structure in which a through hole is provided in the tooth groove of the driven pulley on which the timing belt is stretched without using a dedicated component for lubricating the valve cam. Therefore, the manufacturing cost of the OHC type engine can be reduced.

  Furthermore, according to the present invention, even in a vertical type engine in which it is difficult to directly disperse the lubricating oil up to the valve cam, depending on a repelling tool attached to the crankshaft, the valve cam is efficiently lubricated. Oil can be supplied.

  Furthermore, according to the present invention, since the pair of flange portions sandwiching the tooth gap are provided on the driven pulley, the lubricating oil adhering to the timing belt is efficiently guided to the through hole, and the valve cam in the OHC engine The lubricating performance can be further improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an OHC type engine equipped with a lubricating device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing an intake / exhaust system of the OHC engine shown in FIG. 2, and FIG. 4 is a cross-sectional view taken along line BB in FIG.

  The crankcase 11 of the OHC type engine 10 includes a side wall portion 12a having a substantially cylindrical shape as shown in FIG. 2, and a top wall portion 12b integrally provided on the upper portion of the side wall portion 12a as shown in FIG. A case main body 12 having an oil pan 13 attached to a lower portion of the side wall portion 12a is provided, and a crank chamber 11a is formed therein. A crankshaft 14 is mounted in the crankcase 11 so as to face in the vertical direction, that is, in the vertical direction. The upper end portion of the crankshaft 14 is rotatably supported by the top wall portion 12b via a ball bearing 15, and the lower end portion is A cylindrical portion 16 provided in the oil pan 13 is rotatably supported. In the oil pan 13, the lubricating oil L supplied to the sliding portion of each member constituting the engine, that is, the lubricating oil requesting portion is accommodated, and the lubricating oil L leaks from between the crankshaft 14 and the oil pan 13. In order to prevent this, an oil seal 17 is attached to the oil pan 13. As described above, the OHC type engine 10 is a vertical type in which the crankshaft 14 is arranged in the vertical direction, and the OHC type engine 10 is used as a power source for a mowing (mowing) machine or a brush cutter. In this case, a cutting blade for mowing is connected to the lower end portion of the crankshaft 14 directly or via a shaft (not shown).

  A cylinder 18 is integrally provided in the case main body 12, and a piston 20 is removably mounted in a cylinder bore 19 formed in the cylinder 18 so as to face the horizontal direction. The piston 20 is connected to a connecting rod. The crankshaft 14 is rotated by the reciprocating motion of the piston 20. A cylinder head 22 is attached to the cylinder 18, and a combustion chamber 23 is formed by the cylinder head 22, the cylinder 18, and the piston 20. As shown in FIG. 3, the cylinder head 22 includes an intake port 24 that supplies an air-fuel mixture to the combustion chamber 23 and an exhaust port 25 that discharges combustion exhaust gas, and an intake pipe 26 that communicates with the intake port 24. An exhaust pipe 27 communicating with the exhaust port 25 is attached to the cylinder head 22. A spark plug 30 for igniting the air-fuel mixture in the combustion chamber 23 is attached to the cylinder head 22 as shown in FIG.

  As shown in FIG. 3, the cylinder head 22 is provided with an intake valve that opens and closes an intake port 24, that is, an intake valve 31, and an exhaust valve that opens and closes an exhaust port 25, that is, an exhaust valve 32. Is assembled so that it can be turned up and down. The camshaft 33 is provided with a valve cam 34. The valve cam 34 is formed integrally with the camshaft 33 and rotates together with the camshaft 33. As shown in FIG. 2, a timing belt 37 is stretched between a driving pulley 35 fixed to the crankshaft 14 and a driven pulley 36 fixed to the camshaft 33, and the camshaft 33 is connected to the crankshaft 14. When the crankshaft 14 rotates twice, the camshaft 33 rotates once. As shown in FIG. 3, the rocker shaft 38 provided in the cylinder head 22 drives the rocker arm 39 a that opens and closes the intake valve 31 at a predetermined timing by the rotation of the valve cam 34 and drives the exhaust valve 32 to open and close. A rocker arm 39b is swingably mounted. As described above, in the OHC type engine 10, the cam shaft 33 that opens and closes the intake valve 31 and the exhaust valve 32 is provided on the cylinder head 22, and the valve cam 34 provided on the cam shaft 33 contains the lubricating oil L. The oil pan 13 is arranged so as to be shifted in the horizontal direction.

  Reference numeral 40 denotes a tensioner for applying a predetermined tension to the timing belt 37.

  As shown in FIG. 1, an engine cover 41 is attached above the crankcase 11 so as to cover it, and a cooling fan 42 fixed to the upper end of the crankshaft 14 is disposed in the engine cover 41. The cooling fan 42 generates cooling air that flows along the outer surface of the crankcase 11 by the rotation of the crankshaft 14. A recoil pulley 43 of a recoil starter for starting the engine is rotatably mounted on the engine cover 41, and a recoil rope 44 is wound around the recoil pulley 43. On the other hand, a rotating cylinder 45 is attached to the crankshaft 14, and the recoil pulley 43 is engaged with the rotating cylinder 45 when it is rotated, and the rotation of the recoil pulley 43 is transmitted to the crankshaft 14. A coupling mechanism 46 is provided. Therefore, when the operator pulls the recoil rope 44 to rotate the crankshaft 14, the crankshaft 14 can be rotated to start the engine.

  As shown in FIG. 4, a governor holder 51 is rotatably mounted on the oil pan 13 in parallel with the crankshaft 14 so that the governor mechanism is configured. A driven gear 53 that meshes with the fixed drive gear 52 is provided, and the governor holder 51 is rotationally driven by the rotation of the crankshaft 14. As shown in FIG. 4, two governor weights, i.e., weights 54, are swingably attached to the governor holder 51 by pins 55, and a governor shaft 56 that comes into contact with both weights 54 is incorporated. The shaft 56 is fitted to a shaft portion 57 provided on the oil pan 13 so as to be slidable in the axial direction. When the engine rotational speed becomes higher than the specified rotational speed, the weight 54 is swung so that the upper ends of the weight 54 spread toward each other as shown in FIG. As shown in FIG. 2, a governor lever 58 bent in an L shape is rotatably mounted on the crankcase 11 and connected to a throttle valve (not shown). The operating end of the governor lever 58 is the governor lever. Opposite the shaft 56. As a result, when the engine speed becomes higher than the specified speed, the throttle valve (not shown) is closed by the governor mechanism, and the engine speed is maintained at the specified speed.

  As shown in FIGS. 1 and 4, a scraper 60 is attached to the crankshaft 14 in order to supply the lubricating oil L to each lubricating oil request portion of the engine. The scraper 60 is formed by bending a metal plate, and includes a fitting portion 61 and an inclined wall 62 formed by bending downward with respect to the fitting portion 61. The fitting portion 61 is a crank. It is attached to the crankshaft 14 by being press-fitted to the shaft 14. The inclined wall 62 is inclined downward toward the front side in the rotational direction of the crankshaft 14 and is directed in a tangential direction of the rotational locus, and the scraper 60 is attached to the crankshaft 14 except for the upper end portion. It is immersed in the lubricating oil L in the oil pan 13. When the scraper 60 rotates together with the crankshaft 14, the lubricating oil L of the oil pan 13 is repelled upward by the inclined wall 62, and a desired amount of lubricating oil L is supplied toward each lubricating oil request portion of the engine.

  FIG. 5 is a perspective view showing details of the driven pulley shown in FIGS. 1 and 2, FIG. 6 is an enlarged cross-sectional view showing a meshing portion of the driven pulley and the timing belt, and FIG. 6 is a cross-sectional view taken along line AA in FIG.

  As shown in FIG. 5, the driven pulley 36 is fixed to the camshaft 33 and rotates with the camshaft 33, and a cylindrical cylindrical portion 36b formed integrally with the outer periphery of the disc portion 36a. The valve cam 34 is disposed adjacent to the side surface of the disk portion 36 a, and the cylindrical portion 36 b faces the cam surface of the valve cam 34. As shown in FIG. 6, a plurality of teeth 71 are formed in a circumferential direction at a predetermined pitch on the outer peripheral portion of the cylindrical portion 36 a, and a tooth groove 72 is formed between these teeth 71. On the other hand, the timing belt 37 is a toothed belt provided with a plurality of semi-cylindrical teeth 37a arranged at a predetermined pitch corresponding to the pitch of the tooth groove 72 of the driven pulley 36, and these teeth 37a are driven. The timing belt 37 is stretched around the driven pulley 36 in a state of being engaged with the tooth groove 72 of the side pulley 36, that is, in a meshed state. As shown in FIG. 7, a pair of flange portions 36c sandwiching the tooth groove 72 are provided on both axial sides of the cylindrical portion 36a of the driven pulley 36, and the tooth groove of the timing belt 37 is formed by these flange portions 36c. A shift in the axial direction with respect to 72 is restricted. That is, a pulley groove 73 is formed in the driven pulley 36 by the cylindrical portion 36b and the flange portions 36c, and the timing belt 37 is stretched over the driven pulley 36 in a state of being accommodated in the pulley groove 73, and is driven pulley. Separation from 36 is suppressed.

  A through hole 74 is formed in each tooth groove 72 of the driven pulley 36 in order to supply the lubricating oil L adhering to the timing belt 37 to the valve cam 34. As shown in FIG. 6, these through-holes 74 are respectively open along the radial direction of the cam shaft 33 and open to the outer peripheral surface and the inner peripheral surface of the cylindrical portion 36b, and as shown in FIG. 36a is disposed on the same side (upper side) as the valve cam 34, that is, each through hole 74 is formed in the cylindrical portion 36b so as to penetrate from the tooth groove 72 toward the valve cam 34. .

  FIG. 8 is a partially cutaway sectional view showing a state in which the lubricating oil is supplied to the valve cam through the through hole. Hereinafter, the supply of the lubricating oil L to the valve cam 34 will be described with reference to FIG. To do.

  When the engine starts and the crankshaft 14 rotates, the rotation is transmitted to the camshaft 33 via the driving pulley 35, the timing belt 37, and the driven pulley 36, and the intake valve 31 and the exhaust valve are rotated by the rotation of the camshaft 33. 32 is opened and closed. Further, when the crankshaft 14 rotates, the lubricating oil L in the oil pan 13 is repelled by the scraper 60 attached thereto, and the lubricating oil L is supplied to a lubricating oil requesting portion such as a sliding portion of the crankshaft 14. The

  On the other hand, a part of the lubricating oil L repelled by the scraper 60 adheres to a portion between the teeth of the timing belt 37 that moves from the driving pulley 35 toward the driven pulley 36, and is driven together with the timing belt 37. Move towards 36. When the timing belt 37 to which the lubricating oil L adheres reaches the driven pulley 36, the lubricating oil L adhering between the teeth of the timing belt 37 is taken into the tooth groove 72 of the driven pulley 36, and the timing belt 37. Further moves and the teeth 37a of the timing belt 37 mesh with the tooth grooves 72 of the driven pulley 36, the space of the tooth grooves 72 is gradually narrowed by the teeth 37a of the timing belt 37, and the lubricating oil L in the tooth grooves 72 is reduced. Is injected toward the valve operating cam 34 through the through hole 74 (in the direction indicated by the arrow in FIG. 8). At this time, since both ends in the axial direction of the tooth groove 72 are closed by the pair of flange portions 36c, the lubricating oil L taken into the tooth groove 72 does not leak from both axial sides of the tooth groove 72, The fuel is efficiently injected toward the valve cam 34 through the through hole 74. As the timing belt 37 continuously moves, the lubricating oil L adhering between the teeth of the timing belt 37 is sequentially supplied toward the valve cam 34 through the through holes 74 of the driven pulley 36. As a result, the valve operating mechanisms such as the valve operating cam 34 and the rocker arms 39a and 39b are lubricated.

  As described above, in the OHC type engine 10, the through hole 74 penetrating toward the valve cam 34 is formed in the tooth groove 72 of the driven pulley 36 fixed to the cam shaft 33, and the lubrication adhered to the timing belt 37. Since the oil L is supplied to the valve cam 34 through the through hole 74, the lubricating performance of the valve cam 34 in the OHC engine 10 can be improved. In particular, the valve cam 34 is arranged so as to be displaced in the horizontal direction with respect to the oil pan 13, and it is difficult for the scraper 60 attached to the crankshaft 14 to directly spray the lubricating oil L to the valve cam 34. When the lubricating device of the present invention is applied to a vertical engine, the lubricating oil L can be efficiently supplied to the valve cam 34.

  Further, in this OHC type engine 10, a through hole 74 is simply provided in the tooth groove 72 of the driven pulley 36 around which the timing belt 37 is stretched without using a dedicated part for lubricating the valve cam 34. Since the lubricating oil L can be efficiently supplied to the valve operating cam 34 with a simple structure, the manufacturing cost of the OHC type engine 10 can be reduced.

  Further, in this OHC type engine 10, a pair of flange portions 36 c sandwiching the tooth groove 72 is provided on the driven pulley 36, and the lubricating oil L taken into the tooth groove 72 from the timing belt 37 is difficult to leak out from the tooth groove 72. Therefore, the lubricating oil L taken into the tooth gap 72 can be efficiently guided to the through hole 74, and the lubricating performance of the valve cam 34 in the OHC type engine 10 can be further improved.

  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, the illustrated OHC engine 10 is a vertical type in which the crankshaft 14 and the camshaft 33 are arranged in the vertical direction. However, the present invention is not limited to this, and the crankshaft 14 and the camshaft 33 are arranged horizontally. It is good also as a made type.

  Further, the OHC type engine 10 is not limited to a power source for a mowing (lawn mower) or a brush cutter, but may be used as a power source for other devices such as a generator. When used as a power source for a generator, a power generator is attached to the lower end of the crankshaft 14.

  Furthermore, in the present embodiment, the present invention is applied to the OHC type (SOHC type) engine 10 having one camshaft 33. However, the present invention is not limited to this, and the intake side and the exhaust for opening and closing the intake valve 31 are used. The present invention may be applied to an OHC type (DOHC type) engine having two camshafts 33 on the exhaust side for opening and closing the valve 32.

  Further, in the present embodiment, the scraper 60 that has the inclined wall 62 is used as the scraper 60 that scatters the lubricating oil L accommodated in the oil pan 13, but is not limited thereto, and the lubricating oil L is repelled. If possible, other shapes of scrapers may be used, and other repellents such as impellers may be used instead of the scrapers.

  Furthermore, in this embodiment, the driven pulley 36 is fixed to the cam shaft 33 integrally formed with the valve cam 34. However, the present invention is not limited to this, and the valve cam 34 is attached to the cam shaft 33. The valve cam 34 may be fixed to or integrally formed with the driven pulley 36 while being rotatably provided.

It is a longitudinal section showing an OHC type engine provided with a lubricating device which is one embodiment of the present invention. It is sectional drawing which follows the AA line in FIG. FIG. 3 is a cross-sectional view showing an intake / exhaust system of the OHC type engine shown in FIGS. 1 and 2. It is sectional drawing which follows the BB line in FIG. It is a perspective view which shows the detail of the driven pulley shown to FIG. 1 and FIG. It is an expanded sectional view which expands and shows the meshing part of a driven pulley and a timing belt. It is sectional drawing which follows the AA line in FIG. It is a partially cutaway sectional view showing a state where lubricating oil is supplied to the valve operating cam through the through hole.

Explanation of symbols

10 OHC type engine 11 Crankcase 14 Crankshaft 22 Cylinder head 31 Intake valve (intake valve)
32 Exhaust valve (exhaust valve)
33 cam shaft 34 valve drive cam 35 driving pulley 36 driven pulley 36c flange 37 timing belt 72 tooth groove 74 through hole L lubricating oil

Claims (3)

A lubrication device for an OHC engine in which a camshaft for opening and closing an intake valve and an exhaust valve is provided in a cylinder head,
A driven pulley on which a timing belt is stretched between a driving pulley fixed to a crankshaft is fixed to the camshaft;
Forming a through-hole penetrating toward the valve cam of the cam shaft in a tooth groove engaged with the timing belt of the driven pulley;
A lubricating device for an OHC type engine, characterized in that lubricating oil adhering to the timing belt is supplied to the valve cam through the through hole.   2. The lubrication device for an OHC engine according to claim 1, wherein the crankshaft is mounted on the crankcase in a vertical direction.   3. The lubrication device for an OHC engine according to claim 1, wherein a pair of flange portions sandwiching the tooth gap are provided on the driven pulley.

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