Portable 4-cycle engine and portable machine equipped with the 4-cycle engine

Abstract

A portable 4-cycle engine with a configuration which allows cooling air to flow in the direction of the crankshaft relative to a cylinder head on a cylinder, and a portable machine equipped with this engine, are provided, respectively. In such an engine, the cylinder is separated from the cylinder head including a combustion chamber formed at the cylinder side therein. The engine further comprises a valve train area formed in the cylinder head at the downwind side of the cooling air, and a plurality of vertical fins protruding upward from the cylinder head and extending in the direction of the crankshaft. The valve train area and the plurality of vertical fins are all integrally formed with the cylinder head, so that the cylinder head can be made thinner and lighter with high rigidity to enable the portable machine to become smaller, lighter, and more powerful.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention will become clear from the following description with reference to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a conventional 4-cycle engine equipped on a portable machine;

FIG. 2 is a cross-sectional view of a portable machine equipped with the 4-cycle engine according to one embodiment of the present invention;

FIG. 3 is a perspective view of the outer appearance of the portable 4-cycle engine according to one embodiment of the present invention;

FIG. 4 is a top view of the portable 4-cycle engine according to one embodiment of the present invention;

FIG. 5 is a cross-sectional view taken along the line A-A of FIG. 4;

FIG. 6 is a cross-sectional view taken along the line G-G of FIG. 5;

FIG. 7 is a cross-sectional view taken along the line X-X of FIG. 5;

FIG. 8 illustrates one example of use of the portable machine equipped with the 4-cycle engine according to one embodiment of the present invention; and

FIG. 9 illustrates another example of use of the portable machine equipped with the 4-cycle engine according to another embodiment of the present invention.

Claims

1. A portable 4-cycle engine allowing cooling air to flow in a direction of a crankshaft, comprising: a cylinder;a cylinder head separably disposed on said cylinder, and including a combustion chamber at a side of said cylinder;a cooling fan for introducing the cooling air to said cylinder head, said cooling fan being connected with an end of the crankshaft;a valve train area formed at the downwind side of said cooling air in said cylinder head; anda plurality of vertical fins protruding upward from said cylinder head and extending in the direction of said crankshaft,wherein said valve train area and said plurality of vertical fins are integrally formed with said cylinder head.

2. The portable 4-cycle engine according to claim 1, wherein said combustion chamber is formed in a wedge shape.

3. The portable 4-cycle engine according to claim 1, wherein said vertical fins are formed at a side of said cooling fan of said cylinder head.

4. The portable 4-cycle engine according to claim 1, wherein an exhaust port is formed integrally with said cylinder head, and at least one of said vertical fins and an ignition plug are located at the side of said cooling fan so that the cooling air is introduced to an outer circumference of said exhaust port.

5. The portable 4-cycle engine according to claim 4, further comprising an intake valve and an exhaust valve provided in said cylinder head, wherein said ignition plug is oppositely inclined to said intake valve and said exhaust valve substantially at an equal angle relative to a plane including a centerline of said cylinder and being orthogonal to said crankshaft.

6. A portable 4-cycle engine allowing cooling air to flow in a direction of a crankshaft, comprising: a cylinder;a cylinder head disposed on said cylinder, and including a combustion chamber at a side of said cylinder;an intake port and an exhaust port, said both ports being oppositely formed with each other in said cylinder head in a direction orthogonal to said crankshaft;a cooling fan for introducing the cooling air to said cylinder head, said cooling fan being connected to an end of the crankshaft;a valve train area formed above said intake port and said exhaust port; anda plurality of vertical fins protruding upward from said cylinder head and extending in the direction of said crankshaft,wherein said valve train area and said plurality of vertical fins are integrally formed with said cylinder head.

7. The portable 4-cycle engine according to claim 6, wherein at least one of said vertical fins is connected to said valve train area at one end of a direction orthogonal to said crankshaft.

8. The portable 4-cycle engine according to claim 6, wherein said valve train area is connected to said intake port and said exhaust port with a pair of valve guide bosses; said vertical fins are located at positions away from respective centers of said pair of valve guide bosses.

9. The portable 4-cycle engine according to claim 8, wherein said cylinder head, said intake port, said exhaust port, said valve guide bosses, and a bottom of said valve train area together form an opening, through which the cooling air flows.

10. The portable 4-cycle engine according to claim 9, wherein said opening is formed to have a decreasing cross-sectional area from an upwind side toward a downwind side of said cooling air.

11. The portable 4-cycle engine according to claim 9, wherein a push rod guide having bores for accommodating a pair of push rods is formed in said valve train area at the downwind side of said cooling air; said valve train area has a bottom inclining downwards from the upwind side of said cooling air toward the side of said push rod guide; andthe upwind side of said valve train area is connected to said intake port and said exhaust port with said vertical fins.

12. The portable 4-cycle engine according to claim 9, wherein said intake port and said exhaust port have centerlines located at the downwind side relative to the centerline of said cylinder.

13. The portable 4-cycle engine according to claim 6, wherein said combustion chamber is formed in a wedge shape.

14. The portable 4-cycle engine according to claim 6, wherein: said cylinder head includes a plurality of bolt head shoulders having holes for bolts to tighten said cylinder head with said cylinder;said intake port and said exhaust port have centerlines located at the downwind side relative to the centerline of said cylinder; andsaid intake port, said exhaust port, and said vertical fins are located in the vicinity of said plurality of bolt head shoulders.

15. A portable machine equipped with a 4-cycle engine allowing cooling air to flow to a cylinder head on a cylinder in a direction of a crankshaft, Said 4-cycle engine comprising:a cylinder;a cylinder head separably disposed on said cylinder, and including a combustion chamber at a side of said cylinder;a cooling fan for introducing the cooling air to said cylinder head, said cooling fan being connected to an end of said crankshaft;a valve train area formed at the downwind side of said cooling air in said cylinder head; anda plurality of vertical fins protruding upward from said cylinder head and extending in the direction of said crankshaft,wherein said valve train area and said plurality of vertical fins are integrally formed with said cylinder head.

16. The portable machine equipped with a 4-cycle engine according to claim 15, wherein said combustion chamber is formed in a wedge shape.

17. The portable machine equipped with a 4-cycle engine according to claim 15, wherein said vertical fins are formed on said cylinder head at a side of said cooling fan.

18. The portable machine equipped with a 4-cycle engine according to claim 15, wherein an exhaust port is formed integrally with said cylinder head, and at least one of said vertical fins and an ignition plug are located at the side of said cooling fan so that the cooling air is introduced to an outer circumference of said exhaust port.

19. The portable machine equipped with a 4-cycle engine according to claim 18, said engine further comprising an intake valve and an exhaust valve provided in said cylinder head, wherein said ignition plug is oppositely inclined to said intake valve and said exhaust valve substantially at an equal angle relative to a plane including a centerline of said cylinder and being orthogonal to said crankshaft.

20. The portable machine equipped with a 4-cycle engine according to claim 15, wherein said portable machine is a blower.

21. A portable machine equipped with a 4-cycle engine allowing cooling air to flow to a cylinder head on top of a cylinder in a direction of a crankshaft, said 4-cycle engine comprising:a cylinder;a cylinder head disposed on said cylinder, and including a combustion chamber at a side of said cylinder;an intake port and an exhaust port, said both ports being oppositely formed with each other in said cylinder head in a direction orthogonal to said crankshaft;a cooling fan for introducing the cooling air to said cylinder head, said cooling fan being connected to an end of the crankshaft;a valve train area formed above said intake port and said exhaust port; anda plurality of vertical fins protruding upward from said cylinder head and extending in the direction of said crankshaft,wherein said valve train area and said plurality of vertical fins are integrally formed with said cylinder head.

22. The portable machine equipped with a 4-cycle engine according to claim 21, wherein said portable machine is a bush cutter.