Vehicle Power Unit with Fluid Pump Mediator for Gear Backlash Control
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Solution Overview
Problem
Conventional vehicle power units with balancer mechanisms experience backlash noise and increased weight due to gear diameter and weight requirements, leading to enlarged crankcases and overall power unit size, especially with long intervals between the crank and balancer shafts.
Innovation Solution
A power unit design featuring power transmission gears supported on gear shafts between the crank and balancer shafts, with a fluid pump on one gear shaft to reduce rotational fluctuations and noise, allowing for downsized gear wheels and crankcase, and incorporating a compact arrangement of auxiliary machinery to reduce size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive gear and driven gear are arranged between the crank shaft and the balancer shaft with increased backlash due to temperature variations, then the power transmission is maintained, but backlash noise occurs between the gears
Solution Approach 1:
A fluid pump is introduced as an intermediary component on the driven gear shaft. The pump generates hydraulic pressure that acts as a mediator to suppress backlash between meshing gears, eliminating noise while maintaining power transmission reliability under temperature variations
2Reliability
If the drive gear and driven gear increase in diameter to accommodate long interval layout between crank shaft and balancer shaft, then the power transmission is maintained, but the gear weight increases
Solution Approach 1:
The fluid pump serves as a mediator that enables the use of smaller diameter gears by providing hydraulic pressure to maintain meshing contact. This allows downsizing of gears while preserving power transmission reliability over long shaft intervals
3Reliability
If the drive gear and driven gear increase in diameter, then the power transmission is maintained, but the crankcase must be enlarged outward
Solution Approach 1:
The fluid pump introduces hydraulic pressure as a mediator that enables compact gear design. This allows maintenance of power transmission reliability without enlarging the crankcase outward, achieving a compact engine layout
4Area of stationary object
If the gear diameter is reduced to downsize the crankcase, then the crankcase size is reduced, but the backlash noise increases
Solution Approach 1:
The fluid pump provides hydraulic pressure as a mediator that compensates for the increased backlash inherent in smaller gears. This enables crankcase downsizing while suppressing noise through active backlash control via the pump pressure
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
The solution effectively reduces backlash noise and weight, downsizes the crankcase and entire power unit, and enhances engine cooling efficiency, preventing abnormal combustion and improving engine performance.
Implementation Method 1
transmission of the rotational fluctuation of the crank shaft to the balancer shaft is reduced by rotational resistance of the fluid pump provided on the shaft of one of the power transmission gears
Implementation Method 2
a pair of power transmission gears for transmitting rotation of the crank shaft to the balancer shaft is arranged between the crankcase and the crankcase cover, the power transmission gears being supported on power transmission gear shafts, respectively
Data Source
AI summary
In a vehicle power unit having an internal combustion engine, a pair of power transmission gears for transmitting rotation of a crank shaft to a balancer shaft is arranged between a crankcase and a crankcase cover, and a fluid pump is provided on a power transmission gear shaft supporting a power transmission gear, by which the backlash between the crank shaft and the balancer shaft is reduced and the friction and the noise of the gears are restrained while achieving downsizing of the gears of the crank shaft and the balancer, weight reduction and downsizing of the power unit.