Swing Balancer Mechanism for Compact Motorcycle Crankcase
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Solution Overview
Problem
The existing configuration of balancer weights in saddle-ride type vehicles, such as motorcycles, results in a wide crankcase that reduces operability and ride comfort due to the projection of the side end, narrowing the step and space around the occupant's legs.
Innovation Solution
A saddle-ride type vehicle with a swing balancer mechanism where the crankshaft is housed in a crankcase with a rotational center line parallel to the vehicle-width direction, featuring a swing member that swings in the front-rear direction synchronized with the crankshaft rotation, and a coupling member positioned on the intermediate portion of the bearing portions, allowing for a compact crankcase design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a balancer weight swings in the direction perpendicular to the reciprocating direction of the piston synchronized with crankshaft rotation, then vibrations in the perpendicular direction are reduced, but the crankcase width increases and side end projects
Solution Approach 1:
The swing member is repositioned from the side end of the crankcase to the front end, changing the spatial dimension of the balancing mechanism. This dimensional shift allows the swing member to reduce perpendicular vibrations while preventing crankcase width increase, as the swinging action occurs in the front-rear direction rather than expanding the side width.
Solution Approach 2:
The swing member is configured to dynamically swing in the front-rear direction synchronized with crankshaft rotation, rather than being statically positioned at the side end. This dynamic positioning allows the balancer weight to effectively counteract perpendicular vibrations while maintaining a compact crankcase width, as the balancing function is achieved through motion rather than static extension.
2Object-affected harmful factors
If the crankcase houses the swing member with side end projection, then vibration reduction is achieved, but the step and space around occupant's legs are narrowed
Solution Approach 1:
The swing member is repositioned from the side end to the front end of the crankcase, changing the spatial arrangement from a side-protruding configuration to a front-protruding configuration. This dimensional change preserves the vibration reduction function while eliminating the encroachment on occupant space, as the swing member now extends in the front-rear direction rather than increasing the crankcase width that would affect leg space.
3Length of stationary object
If the coupling member is disposed on the intermediate portion of bearing portions, then the crankcase can be made compact, but the swing member arrangement becomes more complex
Solution Approach 1:
The coupling member disposed on the intermediate portion of the bearing portions serves multiple functions: it connects the swing member to the crankshaft, provides a mounting point for the balancer weight, and maintains the compact crankcase structure. This multi-functional design consolidates several components into one location, reducing overall complexity despite the unusual positioning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the operability and ride comfort by reducing vibrations in the front-rear direction, maintaining a compact crankcase that does not encroach on the occupant's space, thus enhancing the overall riding experience.
Implementation Method 1
a swing member (61) having one end portion coupled to the crankshaft (55) by a coupling member (62), and another end portion supported on the crankcase (51). The swing member (61) swings in an approximately front-rear direction synchronized with a rotation of the crankshaft (55)
Data Source
AI summary
An engine unit of a motorcycle includes a crankshaft, a piston, and a swing member. The crankshaft is housed in a crankcase in a direction such that a rotational center line is parallel to a vehicle-width direction. The piston is disposed above the crankshaft and reciprocates in an approximately up-down direction. The swing member is disposed forward of the crankshaft and the piston, coupled to the crankshaft by a coupling member, and swings in an approximately front-rear direction synchronized with a rotation of the crankshaft.