Transmission Case Cover Scratch Protection and Cooling

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Solution Overview

Problem

The existing power units of saddle-type vehicles face the issue of scratching the painted surface of the transmission case cover during the erection operation of the main stand, while also requiring effective cooling of the belt-type continuously variable transmission.

Innovation Solution

The power unit design includes a wind-guide duct cover with a duct cover rear part that extends beyond the operation part's position when retracted, covering the area prone to foot contact and made of colored resin to minimize visibility of scratches, while maintaining a large exposed area for heat dissipation through vehicle wind.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the transmission case cover is made of metal with a painted surface to maintain appearance quality, then the aesthetic quality is improved, but the surface is prone to scratching during main stand erection operation

Engineering Contradiction:
Improveappearance qualityVSAvoidscratch damage
Core Design Contradiction:
ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a rubber sheet as an intermediary protective layer between the rider's foot and the transmission case cover. This rubber sheet is粘贴 (pasted) on the transmission case cover at the location where the foot contacts during main stand erection, thereby preventing direct contact between the foot and the painted metal surface, and avoiding scratches while maintaining the original appearance quality

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies a rubber sheet in advance on the transmission case cover at the anticipated foot contact area. This beforehand protective measure ensures that when the rider erects the main stand, the foot contacts the soft rubber material instead of the hard painted surface, preventing damage before it can occur

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If the wind-guide duct cover covers more area to protect against foot contact, then the protection against scratching is improved, but the heat dissipation area of the transmission case cover is reduced

Engineering Contradiction:
Improvescratch protectionVSAvoidheat dissipation efficiency
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent applies the rubber sheet only at the specific local area where foot contact occurs during main stand erection, rather than covering the entire transmission case cover. This localized protection approach ensures that scratch protection is provided exactly where needed, while the rest of the transmission case cover remains exposed for effective heat dissipation

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent extracts the protective function from a potential full-coverage wind-guide duct cover design and isolates it to only the necessary foot contact area using a rubber sheet. This extraction allows the majority of the transmission case cover to remain uncovered and maintain its heat dissipation functionality

Inventive Principle:
Principle #2Taking out (Extraction)

3Object-affected harmful factors

If a wind-guide duct cover is used to cover the transmission case cover, then protection against foot contact is improved, but the cooling effect through exposed area is reduced

Engineering Contradiction:
Improvefoot contact protectionVSAvoidcooling effect
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent uses a simple, inexpensive rubber sheet as a protective element instead of a complex, expensive wind-guide duct cover. The rubber sheet can be easily replaced if worn, and its simple construction does not interfere with the cooling function of the transmission case cover

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The rubber sheet is positioned only at the specific location where foot contact occurs, leaving the rest of the transmission case cover exposed to maintain cooling efficiency through vehicle travel wind

Inventive Principle:
Principle #3Local quality

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 effectively prevents scratches on the transmission case cover and maintains efficient cooling of the belt-type continuously variable transmission by ensuring adequate heat dissipation.

Implementation Method 1

the part other than the front part, not covered by the wind-guide duct cover, has a comparatively large surface area exposed to the outside, so that the transmission case cover is efficiently cooled by heat dissipation due to the exposure to the vehicle travel wind

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3339076B1Power unit for saddle-type vehicle
Publication Date: 2020.05.20 HONDA MOTOR CO LTD
  • EP3339076B1 patent drawingFigure 1
  • EP3339076B1 patent drawingFigure 2
  • EP3339076B1 patent drawingFigure 3

AI summary

A power unit P of a saddle-type vehicle has a main stand 30, a transmission case 21T extending rearward from a crankcase 21c that bears a crankshaft 20 in vehicle-width direction in an internal combustion engine E forming the power unit P, and a transmission case cover 60 defining a belt chamber 55, made of a metal and covering the outer lateral side of the transmission case 21T in the vehicle-width direction. A cooling wind inlet 61 is provided at a front part of the transmission case cover 60, and a wind-guide duct cover 80 covers at least the front part including the cooling wind inlet 61 from outside with respect to the vehicle-width direction, so as to guide external air into the cooling wind inlet 61. A duct cover rear part 80r on the rear side of this wind-guide duct cover 80 is extended to the rear beyond a main stand operation part 33 in a retracted state of the main stand 30. The transmission case cover is exposed to keep a cooling effect for the belt chamber by vehicle travel wind, and scratching of a painted surface of the transmission case cover accompanying erection operation of the main stand is suppressed.