JP4034410B2 - Camshaft drive structure of internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camshaft drive structure for opening and closing an intake valve and an exhaust valve of an internal combustion engine.
[0002]
[Prior art]
In a four-cycle internal combustion engine, in order to open and close the intake valve and the exhaust valve at a predetermined timing, the intake valve and the exhaust valve are pressed and opened / closed by a cam provided on a cam shaft that rotates in synchronization with the crankshaft. A valve cam mechanism is used. Such a cam mechanism transmits the rotation of the crankshaft provided on the cylinder block side of the engine to the camshaft provided on the upper side of the intake valve and the exhaust valve of the cylinder head via transmission means such as a belt and a chain. Is. This cam shaft rotation drive transmission means is provided between the crankshaft and the camshaft via an intermediate shaft in view of the layout of the engine structure.
[0003]
FIG. 6 shows a conventional example of a cam shaft drive structure through such an intermediate shaft. FIG. 6 shows a configuration viewed from the front side of the engine. The engine 1 is a four-cycle five-cylinder engine, and includes a cylinder block 2 and a cylinder head 3 fixed on the cylinder block 2. The cylinder head 3 is provided with five intake ports 4 communicating with each cylinder in series (exhaust ports are not shown). A cam shaft 5 constituting an SOHC type cam mechanism is provided on the upper portion of the cylinder head 3.
[0004]
A crankshaft (not shown) is mounted in the cylinder block 2, and a cover (not shown) is mounted on the flange mating surface 6. A first intermediate shaft 8 connected to the crankshaft via a gear 7 is mounted inside the flange mating surface 6 covered with this cover. The first intermediate shaft 8 is rotatably supported by the cylinder block 2 via a plurality of journals (bearings) 9.
[0005]
The first intermediate shaft 8 is connected to a second intermediate shaft 11 provided in the cylinder head 3 via a first chain 10. In this case, the sprocket 13 at the end of the second intermediate shaft 11 with which the first chain 10 engages is provided below the two intake ports 4 in order to avoid the position of the intake port 4. The second intermediate shaft 11 is connected to the cam shaft 5 via the second chain 12.
[0006]
With such a configuration, the rotation of the crankshaft is transmitted to the first intermediate shaft 8 via the gear 7, and this is transmitted to the second intermediate shaft 11 via the first chain 10. Is transmitted to the camshaft 5. As a result, the cam 5a attached to the camshaft 5 opens and closes the intake valve and exhaust valve (not shown) of each cylinder in synchronization with the crankshaft at a predetermined timing corresponding to the cam shape (position).
[0007]
In this case, since the rotation is transmitted from the crankshaft on the cylinder block side to the camshaft on the cylinder head side via the second intermediate shaft 11 provided in the cylinder head, a cam drive transmission system protrudes from the cylinder block side surface. This makes it possible to reduce the size of the engine by shortening the engine length, and to install a transmission system close to the side of the cylinder block where the cam drive transmission system has been eliminated. It can be used for a compact configuration.
[0008]
[Problems to be solved by the invention]
However, in the conventional camshaft drive structure described above, the second intermediate shaft 11 is provided below the intake port in the cylinder head, so as to avoid interference between the chain and the sprocket around which the chain is wound and the intake port. The layout on the intake port or chain and the first intermediate shaft connected to the intake port or the chain is restricted, and the degree of freedom in design is lowered, so that an optimal layout cannot be obtained.
[0009]
Further, since the chain is disposed between the intake port and the intake port, the attachment / detachment of the chain is obstructed by the intake port, which is difficult and troublesome. Furthermore, in this case, the position of the chain mounted between the intake ports is located inside the journal that supports the first intermediate shaft end. Therefore, at the time of assembling, the chain must be wound before the journal is fastened and the first intermediate shaft is fixed to the cylinder block, which makes it difficult to assemble.
[0010]
Further, since the first chain is wound between the first intermediate shaft on the cylinder block side and the second intermediate shaft on the cylinder head side, the chain cover of the first chain is between the cylinder block and the cylinder head. It is installed across. For this reason, the reliability of the seal by a cover falls.
[0011]
The present invention has been made in response to the above-described prior art, and does not restrict the arrangement of intake ports and the like in the cylinder head, enhances engine performance, and provides an easy-to-assemble and highly reliable structure. The purpose is to provide an engine camshaft drive structure.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a crankshaft mounted on the cylinder block side, a camshaft mounted on the cylinder head side, and a first shaft coupled to the crankshaft via a first rotation transmission means. An internal combustion engine comprising an intermediate shaft, a second intermediate shaft connected to the first intermediate shaft via a second rotation transmission means, and a third rotation transmission means for connecting the second intermediate shaft and the cam shaft. In the engine camshaft drive structure, on one side surface of the cylinder block in a direction orthogonal to the axial direction of the crankshaft, a mating surface extending in the longitudinal direction and the height direction of the cylinder block along the one side surface And the first intermediate shaft and the second intermediate shaft are disposed so as to be positioned on the same plane as the mating surface when viewed from the axial direction of the crankshaft, and both the shafts are disposed within the mating surface. In the second rotation transmission hand Are linked via a first intermediate shaft thereof, to provide a camshaft driving structure for an internal combustion engine, wherein a cover for covering the second intermediate shaft and the second rotation transmitting means mounted on said mating surface.
[0013]
According to this configuration, since the first and second intermediate shafts for rotation transmission interposed between the crankshaft and the camshaft are mounted on the cylinder block side, the position of the intake port in the cylinder head is restricted. do not do. Therefore, an optimum intake port layout can be realized in consideration of engine performance, exhaust emission, and the like.
[0014]
Further, since the position of the rotation transmission means between the first and second intermediate shafts is not restricted by the position of the intake port, the rotation transmission means is arranged at an optimum position on the cylinder block side in consideration of assembling property and reliability. Therefore, workability of maintenance such as assembly and attachment / detachment is improved.
[0015]
Further, since the rotation transmission means between the first and second intermediate shafts is provided on the cylinder block side without straddling the cylinder head, the reliability of the seal when covering the rotation transmission means is improved.
[0016]
Further, in the above configuration, in the present invention, the cylinder head between the intake valve and the exhaust valve is inclined to both sides from the center of the cylinder head to form lash adjuster insertion holes, respectively, and overlaps with the lash adjuster insertion holes on both sides. Provided is a camshaft drive structure for an internal combustion engine, in which one oil passage is formed at a position where the oil passage is formed.
[0017]
According to this configuration, when the intake and exhaust valves on both sides of the cylinder head are driven via the rocker arm below the camshaft and the lash adjuster is disposed between the intake and exhaust valves on both sides of the cylinder head, Since one common oil passage is overlapped with the lash adjuster, oil can be supplied without providing a branched oil supply pipe to each lash adjuster, and the structure is simplified.
[0018]
In this case, one air vent passage is preferably formed at a position overlapping the lash adjuster insertion holes on both sides below the oil passage.
[0019]
With this configuration, since a common air vent passage is formed in each lash adjuster, the lash adjuster can be inserted without providing an air vent passage that is branched separately, and the structure is further simplified.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment, the first rotation transmission means includes a pair of meshing gears mounted on the crankshaft and the first intermediate shaft, and the second rotation transmission means includes a first chain. The third rotation transmission means comprises a second chain.
[0021]
According to this configuration, the rotation of the crankshaft is transmitted to the first intermediate shaft via the gear, which is transmitted to the second intermediate shaft via the first chain, and the camshaft is further transmitted via the second chain. Rotation drive. As a result, a highly reliable transmission structure can be obtained, and in such a transmission structure, effects such as an improvement in the degree of design freedom and an improvement in assembly can be obtained.
[0022]
In a further preferred embodiment, a balancer and an accessory drive pulley are mounted on the first intermediate shaft, and the first intermediate shaft is rotatably supported by a cylinder block at its end by a journal. The first chain is mounted on the outer side of the lens.
[0023]
According to this configuration, the first intermediate shaft can be used as a balancer and a drive shaft of the engine auxiliary machine to be a compact configuration, and the chain is attached to the outside of the journal that supports the first intermediate shaft. Therefore, the chain can be mounted after the intermediate shaft is supported by the journal, the assembly work of the intermediate shaft and the attachment / detachment work of the chain can be facilitated, and the reliability of the assembly structure is improved.
[0024]
【Example】
1, 2, and 3 are a front view, a side view, and a top view, respectively, of an engine showing a camshaft drive structure according to an embodiment of the present invention.
The engine 1 is a four-cycle five-cylinder engine as in the example of FIG. 6 described above, and includes a cylinder block 2 and a cylinder head 3 fixed on the cylinder block 2. The cylinder head 3 is provided with five intake ports 4 communicating with each cylinder in series (exhaust ports are not shown). The upper part of the cylinder head 3 is provided with a cam shaft 5 that constitutes an SOHC type cam mechanism, and a series of cams 5a is mounted for each cylinder.
[0025]
A crankshaft 14 (FIGS. 2 and 3) is mounted in the cylinder block 2, and a crankpin 14a and a crank web 14b are provided for each cylinder (dotted line in FIG. 3), and a piston (not shown) is connected via a connecting rod (not shown). (Not shown). A cooling fan 21 is attached to the end of the crankshaft 14. A gear 7 a is mounted on the crankshaft 14 in accordance with the position of the crank web, and a gear 7 b meshing with the gear 7 a is mounted on the first intermediate shaft 8. The rotation of the crankshaft 14 is transmitted to the first intermediate shaft 8 by the pair of gears 7a and 7b.
[0026]
A plurality of balancers 19 are mounted on the first intermediate shaft 8, and a pulley 20 for driving an engine accessory such as an oil pump or a generator is mounted on the end of the first intermediate shaft 8. The first intermediate shaft 8 is rotatably supported by the cylinder block 2 via a plurality of journals (bearings) 9. The aforementioned gear 7 a is provided close to the inside of the journal 9 at the end of the first intermediate shaft 8, and a sprocket 15 is attached to the outside of this journal 9. The first chain 10 is wound between the sprocket 15 and a sprocket 13 a provided on the second intermediate shaft 11. The second intermediate shaft 11 is provided in the cylinder block 2. Therefore, the chain 10 can be disposed outside the journal 9 at the end of the first intermediate shaft 8 without being restricted by the position of the intake port in the cylinder head as in the above-described conventional example ( FIG. 6 ) . .
[0027]
Thus, by providing the chain 10 on the outside of the journal 9, the chain 10 can be mounted after the first intermediate shaft is fixedly held on the cylinder block by the journal 9, and the first intermediate shaft 8 can be mounted. It is easy and the chain can be easily attached.
[0028]
The gear 7b of the first intermediate shaft 8 is exposed from the mating surface 6 of the cylinder block 2, and this exposed portion is covered with a gear cover portion 17a of a cover 17 (FIG. 2) attached to the mating surface. As shown in FIGS. 1 and 2, the mating surface 6 is formed on one side surface of the cylinder block 2 in a direction perpendicular to the axial direction of the crankshaft 14, and along the one side surface, the longitudinal direction of the cylinder block 2. And extending in the height direction. As shown in FIG. 2, the first intermediate shaft 8 and the second intermediate shaft 11 are disposed so as to be located on the same plane as the mating surface 6 when viewed from the axial direction of the crankshaft 14. The block 2 is rotatably supported. Further, the first chain 10 mounted between the first and second intermediate shafts 8 and 11 connects the first intermediate shaft 8 and the second intermediate shaft 11 within the mating surface 6 as shown in FIG. is doing. The first chain 10 is covered with a chain cover portion 17 b of the cover 17. That is, the cover 17 is attached to the mating surface 6 so as to cover the first intermediate shaft 8, the second intermediate shaft 11, and the first chain 10. Since such a cover 17 is provided only on the cylinder block side and does not extend over the cylinder head side, the reliability of the seal with the mating surface 6 is improved.
[0029]
The second intermediate shaft 11 protrudes from the side surface of the cylinder block 2 and a sprocket 13b is attached to the end thereof. The second chain 12 is wound around the sprocket 13b. The second chain 12 is hung on a sprocket 16 at the end of the camshaft 5 protruding from the side surface of the cylinder head 3. Thus, the second chain 12 provided on the side surface of the engine 1 is covered with the common cover 22.
[0030]
With such a configuration, the rotation of the crankshaft 14 is transmitted to the first intermediate shaft 8 via the gears 7a and 7b, which is transmitted to the second intermediate shaft 11 via the first chain 10, and further to the second intermediate shaft 11. It is transmitted to the camshaft 5 via the chain 12. As a result, the cam 5a attached to the camshaft 5 opens and closes the intake valve and exhaust valve (not shown) of each cylinder in synchronization with the crankshaft at a predetermined timing corresponding to the cam shape (position).
[0031]
4 and 5 are a top view and a cross-sectional view of another embodiment of the present invention.
This embodiment simplifies the structure of the oil supply system to the lash adjuster, especially in the structure having a plurality of lash adjusters on the lower side of the camshaft, and simplifies the structure of the air bleeding system when the lash adjuster is mounted. It is intended. That is, conventionally, two main oil passages are provided on each side of the intake / exhaust valve of the engine, and oil is supplied by providing a branch passage from the main oil passage for each lash adjuster. Also, when a lash adjuster is inserted into the insertion hole when such a lash adjuster is mounted, an air vent hole is required at the back end of the insertion hole. It was provided for each lash adjuster. For this reason, the piping structure around the cam shaft of the cylinder head is complicated, and the production is troublesome.
[0032]
The present embodiment improves such a point.
Each cylinder 31 of the cylinder head 30 is connected to an intake port 32 branched into two and an exhaust port 33. A spark plug insertion hole 45 (FIG. 4) is formed at a branch portion of the intake port 32, and a spark plug 46 (FIG. 5) is attached. An injector insertion hole 47 is formed on the upstream side of the spark plug 46 and an injector (fuel injection valve) 48 is attached.
[0033]
An intake valve 34 is mounted at the end of each intake port 32 facing the combustion chamber 40, and an exhaust valve 35 is mounted at the end of the exhaust port 33, similarly facing the combustion chamber 40. Each intake / exhaust valve 34, 35 is mounted with its valve shaft 41 inserted into a valve guide 42, and is always urged upward by a spring 44 that engages with a spring retainer 43 at its end.
[0034]
This engine is a SOHC type engine, and a cam shaft 36 is attached by a cam cap 37 above each cylinder 31 of the cylinder head 30, and three engines corresponding to the intake and exhaust valves 34 and 35 are provided. A cam 38 is attached. Each cam 38 opens and closes an intake valve 34 or an exhaust valve 35 via a rocker arm 39, respectively.
[0035]
A lash adjuster 49 is engaged with an end portion of each rocker arm 39 that engages with each intake / exhaust valve 34, 35 on the opposite side to the engagement portion, so that the rocker arm 39 always attaches each intake / exhaust valve 34, 35 to each other. The clearance between the valve shaft end is adjusted so that the pressure is properly applied. The lash adjuster insertion holes 50 into which these lash adjusters 49 are inserted are provided so as to be inclined from the center of the cylinder head 30 to both sides corresponding to the intake and exhaust valves 34 and 35 (see FIG. 5).
[0036]
A band-shaped recess 51 is formed in an annular shape somewhat above the center of the side surface of the lash adjuster 49, and a band-shaped annular space is formed between the insertion hole 50 and the lash adjuster 49. Oil is supplied into the lash adjuster 49 through the recess 51. An annular stepped portion 52 is formed at the lower end of each lash adjuster 49, and an annular space is formed between the lash adjuster 49 and the insertion hole 50. An air vent passage 54, which will be described later, is formed in communication with the annular space, and air when the lash adjuster is inserted is released.
[0037]
A common oil passage 53 is formed in the upper part of the center portion of the cylinder head 30 so as to overlap the three lash adjuster insertion holes 50 inclined so as to spread from the center of the cylinder head 30 to both sides. The oil passage 53 is formed at a position that engages with the annular recess 51 of each lash adjuster 49. Thus, by providing a common oil passage 53 so as to overlap each lash adjuster 49, oil is supplied from the oil passage 53 through the recess 51 of each lash adjuster 49. In this case, since the oil passage is common to each lash adjuster, the piping system is simplified.
[0038]
A single air vent passage 54 is formed below the oil passage 53 at a position overlapping the annular space at the lower end of each lash adjuster insertion hole 50. By providing such an air vent passage 54, when the lash adjuster 49 is inserted into the insertion hole 50 and fitted, the air is surely removed from the end in the insertion direction, so that the mounting operation can be facilitated. In this case, since the air vent passage is common to each lash adjuster, the piping system is simplified.
[0039]
【The invention's effect】
As described above, in the present invention, since the first and second intermediate shafts for rotation transmission interposed between the crankshaft and the camshaft are mounted on the cylinder block side, the intake air in the cylinder head Does not constrain port location. Therefore, an optimum intake port layout can be realized in consideration of engine performance, exhaust emission, and the like, and engine performance and emissions can be improved.
[0040]
In addition, since the position of the rotation transmission means composed of, for example, a chain between the first and second intermediate shafts is not restricted by the position of the intake port, the rotation transmission means (chain) is considered on the cylinder block side in consideration of assembly and reliability. Therefore, the workability of maintenance such as assembly and detachment is improved.
[0041]
In addition, since the rotation transmission means (for example, chain) between the first and second intermediate shafts is provided on the cylinder block side without straddling the cylinder head, the reliability of the seal of the cover covering the rotation transmission means (chain) is improved. improves.
[Brief description of the drawings]
FIG. 1 is a main part configuration diagram of an engine according to an embodiment of the present invention as viewed from the front.
FIG. 2 is a main part configuration diagram of the engine of FIG. 1 as viewed from the side.
FIG. 3 is a main part configuration diagram of the engine of FIG. 1 as viewed from above.
FIG. 4 is a top view of an essential part of another embodiment of the present invention.
5 is a cross-sectional view of the embodiment of FIG.
FIG. 6 is a main part configuration diagram of a conventional engine as viewed from the front.
[Explanation of symbols]
1: Engine, 2: Cylinder block, 3: Cylinder head,
4: intake port, 5: cam shaft, 5a: cam, 6: mating surface, 7a, 7b: gear,
8: first intermediate shaft, 9: journal, 10: first chain,
11: second intermediate shaft, 12: second chain,
13a, 13b, 15, 16: sprocket, 17: cover,
17a: gear cover part, 17b: chain cover part, 19: balancer,
20: Auxiliary pulley, 21: Cooling fan, 22: Cover,
30: cylinder head, 31: cylinder, 32: intake port, 33: exhaust port,
34: intake valve, 35: exhaust valve, 36: camshaft, 37: cam cap,
38: cam, 39: rocker arm, 40: combustion chamber, 41: valve shaft,
42: Valve guide, 43: Spring retainer, 44: Spring,
45: spark plug insertion hole, 46: spark plug, 47: injector insertion hole,
48: Injector, 49: Rush adjuster,
50: Rush adjuster insertion hole, 51: annular recess, 52: annular step,
53: Oil passage, 54: Air vent passage.

Claims (5)

A crankshaft mounted on the cylinder block side;
A camshaft mounted on the cylinder head side;
A first intermediate shaft coupled to the crankshaft via first rotation transmission means;
A second intermediate shaft coupled to the first intermediate shaft via a second rotation transmission means;
In the camshaft drive structure for an internal combustion engine comprising the third rotation transmission means for connecting the second intermediate shaft and the camshaft,
On one side surface of the cylinder block in a direction perpendicular to the axial direction of the crankshaft, a mating surface extending in the longitudinal direction and the height direction of the cylinder block along the one side surface is formed,
The first intermediate shaft and the second intermediate shaft are disposed so as to be located on the same plane as the mating surface when viewed from the axial direction of the crankshaft, and both the shafts are disposed in the second surface within the mating surface. Connected via rotation transmission means,
A camshaft drive structure for an internal combustion engine, wherein a cover that covers the first intermediate shaft, the second intermediate shaft, and the second rotation transmission means is attached to the mating surface . The first rotation transmission means comprises a pair of meshing gears mounted on the crankshaft and the first intermediate shaft,
The second rotation transmission means comprises a first chain,
2. The camshaft drive structure for an internal combustion engine according to claim 1, wherein the third rotation transmission unit includes a second chain. A balancer and an accessory driving pulley are mounted on the first intermediate shaft,
This first intermediate shaft is rotatably supported on the cylinder block by a journal at its end,
3. The camshaft drive structure for an internal combustion engine according to claim 2, wherein the first chain is mounted outside the journal. Rush adjuster insertion holes are formed in the cylinder head between the intake valve and the exhaust valve so as to be inclined on both sides from the center of the cylinder head,
2. The camshaft drive structure for an internal combustion engine according to claim 1, wherein one oil passage is formed at a position overlapping with the lash adjuster insertion holes on both sides.   5. The camshaft drive structure for an internal combustion engine according to claim 4, wherein one air vent passage is formed at a position overlapping the lash adjuster insertion holes on both sides below the oil passage.

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