An air-cooled overhead-valve engine comprises a cooling fan connecting to one end portion of crankshaft and surrounding with fan casing, a combustion air intake port provided in the direction of downstream side of cooling air, and push rods for driving a cam arranged in opposite side to said intake port with relate to a center of cylinder. The engine can be used suitable to power lawn mowers and the like.

Patent
   RE33978
Priority
Mar 13 1985
Filed
Apr 29 1991
Issued
Jun 30 1992
Expiry
Apr 29 2011
Assg.orig
Entity
Large
10
4
all paid
3. An engine as set forth in 2, wherein said inlet and exhaust ports are located in said cylinder block along said crankshaft, between said inlet and outlet openings of said fan casing that that said inlet and exhaust ports are directly exposed to the streams of cooling air from said cooling fan.
1. In an air-cooled overhead-valve internal combustion engine, said engine being composed of a crankcase with a crankshaft, a cylinder block with a cylinder head and a combustion chamber mounted in said crankcase, at least a pair of intake and exhaust valves installed in intake and exhaust ports formed in said cylinder head, a valve drive system mounted adjacent to said cylinder block for driving said intake and exhaust valves through cam-driven push rods, an intake pipe connected at one end thereof to said intake port and at its opposite end to an air cleaner and a carburetor, an exhaust duct connected at one end thereof to said exhaust port, a flywheel joined to said crankshaft at the other end of the output side end of said crankshaft and a cooling fan mounted on said flywheel, the improvements wherein said cooling fan is housed, together with said crankcase and flywheel, in a fan casing having a pair of inlet and outlet openings bored in opposite walls thereof, said inlet opening is located at the flywheel side of said crankshaft, while said outlet opening is located at the opposite side of said crankshaft from said flywheel, and said cam-driven push rods are located in said crankcase on that side of said cylinder block far remote from wherein said intake pipe is connected to said intake port, said cooling fan being mounted in said fan casing in such a manner that the cooling air from said cooling fan is allowed to flow in a direction substantially parallel with the axis of said crankshaft, along the surface of said cylinder block and cylinder head.
5. In an air-cooled overhead-valve internal combustion engine, said engine being composed of a crankcase with a crankshaft, a cylinder block with a cylinder head and a combustion chamber mounted in said crankcase, at least a pair of intake and exhaust valves installed in intake and exhaust ports formed in said cylinder head, a valve drive system mounted adjacent to said cylinder block for driving said intake and exhaust valves through cam-driven push rods, an intake pipe connected at one end thereof to said intake port and at its opposite end to an air cleaner and a carburetor, an exhaust pipe connected at one end thereof to said exhaust port, a flywheel joined to said crankshaft at the other end of the output side end of said crankshaft and a cooling fan mounted on said flywheel, the improvements wherein said cooling fan is housed, together with said crankcase and flywheel, in a fan casing having a pair of inlet and outlet openings bored in opposite walls thereof, said inlet opening is located at the flywheel side of said crankshaft, while said outlet opening is located at the opposite side of said crankshaft from said flywheel, and said cam-driven push rods are located in said crankcase on that side of said cylinder block far remote from where said intake pipe is connected to said intake port, said cooling fans being mounted in said fan casing in such a manner that the cooling air from said cooling fan is allowed to flow in a direction substantially parallel with the axis of said crankshaft, along the surface of said cylinder block and cylinder head, an air inlet port formed in said fan casing adjacent said cylinder head upstream with respect to the cooling air flow and at a position where the dynamic pressure due to said fan is low, said inlet port being connected to said air cleaner, and a spark plug mounted in said cylinder head in a space surrounded by said intake and exhaust ports and said push rods.
2. An engine as set forth in claim 1, wherein said intake port is located adjacent to that side of said cylinder block nearer said cooling fan and said intake pipe is laid substantially perpendicularly with the axis of said crankshaft while said exhaust port is located adjacent to that side of said cylinder block far remote from said cooling fan, the axis of said exhaust port extending substantially parallel with the axis of said crankshaft.
4. An engine as set forth in claim 1, wherein said inlet and exhaust ports are located in said cylinder block along said crankshaft, between said inlet and outlet openings of said fan casing so that said inlet and exhaust ports are directly exposed to the streams of cooling air from said cooling fan.
6. An engine as set forth in claim 5, wherein said intake port is located adjacent to that side of said cylinder block nearer said cooling fan and said intake pipe is laid substantially perpendicularly with the axis of said crankshaft while said exhaust port is located adjacent to that side of said cylinder block far remote from said cooling fan, the axis of said exhaust port extending substantially parallel with the axis of said crankshaft.
7. An engine as set forth in claim 6, wherein said intake and exhaust ports are located in said cylinder head along said crankshaft, between said inlet and outlet openings of said fan casing so that said intake and exhaust ports are directly exposed to the streams of cooling air from said cooling fan.
8. An engine as set forth in claim 5, wherein said intake and exhaust ports are located in said cylinder head along said crankshaft, between said intake and outlet openings of said fan casing so that said inlet and exhaust ports are directly exposed to the streams of cooling air from said cooling fan.

(1) Field of the Invention:

The present invention relates to an air-cooled overhead-valve engine suitable to power lawn mowers and the like.

(2) Description of the Prior Art:

Generally, said engine has been broadly adopted to a structure as shown in FIG. 1. As shown in the FIG. 1, a cooling fan 2 mounted to one end portion of crankshaft 1 is received within a fan casing 3. Said fan casing 3 is extended from the vicinity of crankcase 5 to the vicinity of cylinder block 6 and cylinder head 7. Furthermore, the fan casing 3 is provided with a suction air opening formed coaxially with the crankshaft 1 and an exit section opened towards to the cylinder block 6 and the cylinder head 7, respectively. Also, the fan casing 3 is provided with an intake pipe 17, which is formed the intake port 16 is extended from the combustion chamber 20 to an internal part of the cylinder head 7 as shown in the left side of FIG. 5, and the extended end thereof is connected to the carburetor 10. Said carburator 10 is located sidewards the cylinder head 7 and at the substantial same level as that of the cylinder head 7 and further connected to the air cleaner 9. The air cleaner 9 is located upwardly the carburetor 10 and sidewards the fan casing 3 and connected to the air-intake air inlet port 8 of said fan casing 3. The exhaust port 26 is located in the downstream in the direction of the cooling air f' and opened in the vertical direction to the intake port 16, so that a required distance of the exhaust port 26 to a spark plug 25 can be maintained, said spark plug 25 providing being provided between the intake and exhaust valves 11 and the push rods 13, and as a result, it can be improvable to a cooling performance of the spark plug 25.

Furthermore, the push rods 13 are arranged in the opposite side to the intake port 16 as indicated above, and the intake port 16 is not provided between both push rods 13, so that the intake port 16 can be arranged directly without making it the deviated route from both push rods 13. Also, as shown in FIG. 6, the inlet intake pipe 17 is formed integrally with the cylinder head body, so that the inlet intake pipe 17 can be connected directly to the carburetor 10. Thus, the configurative construction can be manufactured substantially in simple and in lower cost.

In addition, the intake port 16 can be formed without making a curve therein and can be formed shortly a length thereof, so that it can be elevated an intake effect of the engine.

Moreover, according to the invention, the cooling air passage 39 surrounded with the wall 35 of combustion chamber 20, the valve guide boss 36, the wall 37 of rock arm chamber and the push rod-through portion 38, respectively is not never intercepted by the inlet intake pipe 17, which is formed the intake port 16, thereby the hot surfaces of the spark plug 25 and the cylinder head 7 can be sufficiently cooled by cooling air.

A numeral 23 shows a filter element provided within the air cleaner 9, and a numeral 24 shows a fly-wheel. Also, a numeral 40 shows a starter motor. In any case, said starter motor 40 is arranged in the opposite side to the intake port 16 in such a manner that the cylinder center 0--0 is inserted between the starter motor 40 and the intake port 16. The starter motor 40 is also mounted to the crankcase 5.

In the operation of the engine, an external cooling air is supplied to the cylinder block 6 and the cylinder head 7 from the cooling fan 2. The combustion air is sucked into the carburetor 10 from the fan casing 3 through the intake inlet port 8 and air cleaner 9, respectively as shown in FIG. 5. Furthermore, the air fuel mixture is sucked into the combustion chamber 20 through the intake port 16 from the carburetor 10. In this operation, even if the intake inlet port 8 is located in the same location shown in FIG. 1, the dust and the like can not be sucked into the intake inlet port 8. In addition, a large dynamic pressure within the fan casing 3 due to cooling fan 2 can not be applied directly to the intake inlet port 8 and also a fuel flow can be easily controlled in the carburetor 10.

Shirai, Tetsuaki

Patent Priority Assignee Title
6044811, Feb 14 1997 Mitsubishi Heavy Industries, Ltd. Air guide casing for air-cooled engine
6055946, Aug 02 1999 International Engine Intellectual Property Company, LLC Crankshaft-mounted cooling fan with power takeoff capability
6837206, Jul 11 2002 Kohler Co. Crankcase cover with oil passages
6837207, Jul 18 2002 KOHLER CO Inverted crankcase with attachments for an internal combustion engine
8419834, Oct 12 2005 Kohler Co. Air cleaner assembly
8585805, Jun 13 2008 Kohler Co. Cyclonic air cleaner
8801819, Oct 12 2005 Kohler Co. Air cleaner assembly
8808432, Jun 13 2008 Kohler Co. Cyclonic air cleaner
9206721, Jun 13 2008 Kohler Co. Cyclonic air cleaner
D793929, Jul 07 2015 Brake backing plate with heat sink
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Executed onAssignorAssigneeConveyanceFrameReelDoc
Apr 29 1991Kawasaki Jukogyo Kabushiki Kaisha(assignment on the face of the patent)
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