Balancer Shaft Taper Connection Torque Transmission
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Solution Overview
Problem
Existing balancer apparatus for internal combustion engines require upsizing of the balancer shaft to increase transmission torque, which compromises the design and efficiency.
Innovation Solution
A balancer apparatus with a gear transmission mechanism featuring a driven gear wheel and a balancer shaft with tapering bearing portions and a tubular boss portion, eliminating the need for a keyway by using a pin and elastic member to absorb backlash, allowing for increased torque without upsizing the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a keyway is used to position the driven gear wheel on the balancer shaft, then the positioning is achieved, but the balancer shaft must be upsized to increase transmission torque
Solution Approach 1:
The connection between the driven gear wheel and balancer shaft is segmented into multiple functional elements: a taper-bored hole in the gear wheel, a corresponding taper portion on the balancer shaft, a positioning pin, and an elastic member. This segmentation allows each element to contribute specifically to torque transmission, positioning, and backlash absorption without requiring overall shaft enlargement
Solution Approach 2:
The connection structure combines different material properties and mechanical characteristics - the elastic member provides flexibility for backlash absorption, the pin provides rigid positioning, and the taper connection provides friction-based torque transmission. This composite approach enables high torque transmission through a smaller shaft diameter
2Power
If the balancer shaft is upsized to increase transmission torque, then the torque capacity increases, but the assembly complexity and manufacturing difficulty increase
Solution Approach 1:
By dividing the connection into separate functional components (taper connection, pin, elastic member), the design achieves high torque capacity without requiring a single oversized shaft, thereby reducing overall device complexity while maintaining performance
Solution Approach 2:
The taper connection changes the geometric parameters of the connection interface, creating a friction-based torque transmission mechanism that is more efficient than keyway connections, allowing smaller shaft dimensions while maintaining torque capacity
3Strength
If a keyway connection is used, then the driven gear wheel is positioned, but the coupling strength between the gear wheel and shaft is insufficient for high torque applications
Solution Approach 1:
The connection combines multiple mechanisms - friction from the taper connection, rigid positioning from the pin, and elastic compliance from the elastic member - creating a composite coupling system that achieves superior strength-to-diameter ratio compared to traditional keyway connections
Solution Approach 2:
The taper connection uses conical geometry instead of cylindrical keyway geometry, creating a friction-based connection that distributes stress more effectively and provides stronger coupling for the same shaft diameter
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
Enhances torque transmission while maintaining the balancer shaft's size, improving assembly and productivity by ensuring precise positioning and reducing interference, thus optimizing the balancer apparatus's performance.
Implementation Method 1
a sub gear wheel for cooperating with the driven gear wheel to absorb a backlash is mounted on the boss portion on the smaller diameter end side of the attachment hole with an elastic member interposed between the sub gear wheel and the driven bear wheel
Data Source
AI summary
A gear transmission mechanism is provided between a crankshaft and the balancer shaft. The balancer shaft includes a pair of bearing portions supported for rotation on a crankcase and a gear wheel supporting portion formed in a tapering shape such that a diameter thereof decreases away from one bearing portion. A tubular boss portion is provided integrally on the driven gear wheel and has a tapering attachment hole in which the gear wheel supporting portion is fitted. A fitting recessed portion in which a pin which has an axial line along a radial direction of the balancer shaft and is fitted at a half portion on one end side thereof in a large diameter end portion of the gear wheel supporting portion is fitted at a half portion on the other end side thereof is provided on the boss portion on the large diameter end side of the attachment hole.