Marine propulsion – Means for accomodating or moving engine fluids – Cooling for engine
Reexamination Certificate
2000-05-10
2001-04-10
Swinehart, Ed (Department: 3617)
Marine propulsion
Means for accomodating or moving engine fluids
Cooling for engine
C440S08900C, C123S1960CP, C123S1950HC
Reexamination Certificate
active
06213826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an outboard motor detachably mounted at a stern for use to propel a boat or ship, as well as an engine mounted in the outboard motor. The engine according to the present invention can be utilized not only as an engine for the outboard motor, but also as a general-purpose engine.
2. Description of the Related Art
In a common type of the outboard motor of the related art, an engine (a vertical engine) having a flywheel provided at an upper end of a vertically directed crankshaft protruding from an engine block is mounted in an outboard motor body case which is mounted to a boat body through an antivibration mount. Such types of the outboard motors are disclosed, for example, In Japanese Patent Application Laid-open Nos.191610/87, 192917/88 and 192918/88.
In these outboard motors, a ring gear is mounted around an outer periphery of the flywheel, and a starter motor is mounted above a side of the engine and meshed with the ring gear. A driving pulley of a valve-operating belt drive transmission is provided at an end of the crankshaft adjacent below the flywheel.
Typically, an ignition power source coil and a charging power source coil are accommodated in the flywheel to form a dynamo and hence, the flywheel has a downwardly-turned bowl-like shape.
In such a prior art outboard motor, the heavy flywheel having a large inertial moment, which largely influences the determination of the gravity of the position of the center of engine, is spaced farther upwardly from the antivibration mount. The crankshaft end opposite from the flywheel is coupled to a driving shaft for transmitting a driving force to a propeller. Therefore, torsional vibrational effects exert a great influence on the selection of the antivibration mount and hence, the selection of the antivibration mount must be taken into special consideration.
In addition, not only the flywheel but also a starter must be mounted above the engine. Therefore, the position of the center of gravity of the engine is high, which increases the moment required during tilting-up of the outboard motor, and also limits the freedom of the disposition of other auxiliaries, especially, in the case of a multi-cylinder engine the disposition of an electrical equipment box for accommodating a CDI unit plurality of coils, other auxiliaries such as and intake system auxiliaries or the like.
Further, in a 4-cycle engine used in the outboard motor, the driving Pulley of the wrapping type transmission is provided as a valve operating device at the crankshaft end adjacent the flywheel. The crankshaft end however requires a large diameter for mounting the flywheel. Therefore, the diameter of the driving pulley must be increased and as a result, a driven pulley adjacent a camshaft also increased in size and has a shape occupying an area near an upper portion of a cylinder head, bringing about an increase in size of an upper portion of a rear end of an engine cover spaced from a tilting shaft. However, this portion of the engine cover is liable to interfere with a boat body structure, when the outboard motor is turned upwardly about the tilting shaft and hence, the unnecessary increase in size of this portion is undesirable and inconvenient even in respect of a moment required for the turning of the outboard motor.
A lower portion of the outboard motor body case is formed to be narrow in order to reduce the underwater resistance of a submerged portion of the case to the utmost and to provide a reduction in weight. Therefore, an engine having a good mountability to such outboard motor body case is desired.
In Japanese Utility Model Application Laid-open Nos.21509/91 and 23609/91, there has been proposed an engine in which a crankshaft is oriented vertically and a flywheel is provided at a lower end of the crankshaft protruding from an engine block. Such an engine includes a transmission connected to that lower end of the crankshaft which is provided with the flywheel. Thus, this engine cannot be applied directly as an engine for use in the outboard motor, and such prior art devices not suggest any means capable of solving problems inherent in the engine of the above-described type for use in the outboard motor.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide an outboard motor a low center of gravity, which is easy to tilt up and is less susceptible to torsional vibration.
It is a second object of the present invention to provide an engine which is excellent in mountability to the outboard motor body case.
To achieve the first object, according to the present invention, there is provided an outboard motor comprising an engine mounted at an upper portion of an outboard motor body case which is swingable about a tilting shaft, with a crankshaft of the engine being directed in a vertical direction, wherein the crankshaft is provided, with a flywheel, at a lower end thereof which protrudes downwardly from an engine body of the engine.
With the above construction, since the flywheel is provided at the lower end of the crankshaft, i.e., at a lower portion of the engine, the position of the center of gravity of the engine is lowered, so that a moment required for swinging the outboard motor upwardly (i.e., tilted up) about the tilting shaft is reduced. Therefore, the effort required of a person when the outboard motor is manually tilted up is reduced. Even when the outboard motor is tilted up by a tilting device such as a hydraulic device or the like, a prompt tilting-up operation can be achieved by a relatively small-sized tilting device. In addition, the flywheel is provided at the lower portion of the engine and moreover, can be accommodated by utilizing a space between a connecting member for supporting the outboard motor body case and the engine body. Therefore, the entire height of the outboard motor is relatively low. Further, the flywheel does not exist above a driving pulley of a valve operating device provided at an upper portion of the engine and therefore, even if the driving pulley is of a sufficiently small diameter, there is no problem for handling the pulley. Consequently, a driven pulley can also be of a small diameter (in a 4-cycle engine, the diameter of a driven pulley is twice the diameter of a driving pulley) and thus, it is possible to reduce the size of the engine and outboard motor because the height can also be lowered. Yet further, a driving force is derived from a crankshaft end on the same side as the flywheel and therefore, it is possible to reduce the torsional vibration of the crankshaft.
To achieve the second object, according to the present invention, there is provided an engine with a crankshaft directed vertically, comprising a flywheel provided at that lower end of the crankshaft which protrudes from an engine block, and an engine mount case coupled to a lower surface of the engine block for mounting the engine, the engine mount case having a peripheral wall which extends below the flywheel to surround at least a portion of the periphery of the flywheel.
With the above construction, notwithstanding the flywheel being provided at the lower portion of the engine, the engine can be easily placed in position through the engine mount case. Particularly, the engine is suitable for use in the outboard motor and can be easily and satisfactorily mounted to the outboard motor body case through the engine mount case.
The above and other objects, features and advantages of the invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 2357942 (1944-09-01), Farr
patent: 2976836 (1961-03-01), Fageol
patent: 4772236 (1988-09-01), Takahashi
patent: 4881510 (1989-11-01), Etoh et al.
patent: 4907551 (1990-03-01), Sakono et al.
patent: 4930467 (1990-06-01), Masuda et al.
patent: 4945887 (1990-08-01), Sakurai et al.
patent: 5036805 (1991-08-01), Yamamoto et al.
patent: 5049100 (1991-09-01), Yamamoto et al.
patent: 516
Koishikawa Kouji
Kuwabara Shigeaki
Suzuki Hitoshi
Tsunoda Masaki
Watanabe Yoshimi
Armstrong, Westerman Hattori, McLeland & Naughton
Honda Giken Kogyo Kabushiki Kaisha
Swinehart Ed
LandOfFree
Outboard motor, and engine thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Outboard motor, and engine thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Outboard motor, and engine thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2460662