Motorcycle Water Pump Layout for Ground Clearance

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Solution Overview

Problem

Straddled vehicles with water-cooled internal combustion engines face challenges in achieving sufficient minimum ground clearance while minimizing vehicle width, as existing designs often result in interference between the exhaust pipe and coolant hose, leading to increased vehicle width and reduced ground clearance.

Innovation Solution

The design positions the water pump directly connected to the coolant passage within the engine, eliminates the hose connecting the water pump and radiator, and arranges the exhaust pipe upward to ensure sufficient ground clearance without increasing vehicle width, by placing the thermostat forward of the cylinder body and inward relative to the exhaust pipe, allowing for a compact layout.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the exhaust pipe is arranged downward of the crankcase to reduce vehicle width, then the vehicle width is reduced, but the minimum ground clearance is insufficient

Engineering Contradiction:
Improvevehicle widthVSAvoidminimum ground clearance
Core Design Contradiction:
Length of moving objectVSShape

Solution Approach 1:

The exhaust pipe is repositioned from a horizontal arrangement (sideward of the hose) to a vertical arrangement (upward of the water pump), utilizing the vertical dimension to resolve the conflict between vehicle width and ground clearance. This dimensional change allows the exhaust pipe to clear the ground while maintaining a compact horizontal footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the hose connects the water pump and radiator, then the coolant flow path is established, but the hose interferes with the exhaust pipe arrangement

Engineering Contradiction:
Improvecoolant flow pathVSAvoidcomponent interference
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hose connecting the water pump and radiator is removed from the system. Instead, the water pump is directly integrated with the coolant passage, eliminating the intermediate hose that caused interference with the exhaust pipe arrangement.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The water pump and coolant passage are merged into a direct connection, eliminating the separate hose component. This integration simplifies the overall structure and removes the source of interference between cooling and exhaust systems.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If the exhaust pipe is arranged sideward of the hose to avoid interference, then component interference is avoided, but the vehicle width increases

Engineering Contradiction:
Improvecomponent interferenceVSAvoidvehicle width
Core Design Contradiction:
Device complexityVSLength of moving object

Solution Approach 1:

The exhaust pipe is moved from a horizontal arrangement (sideward) to a vertical arrangement (upward), utilizing the vertical dimension to avoid interference with the water pump while maintaining a compact horizontal footprint. This resolves the contradiction by changing the spatial dimension of arrangement.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 ensures a sufficient minimum ground clearance while reducing the vehicle's width, preventing interference between the exhaust pipe and water pump, and allows for a larger thermostat, enhancing coolant flow and reducing vibrations during engine operation.

Implementation Method 1

a water pump attached to the side wall of the crankcase; an inlet and an outlet connected directly to the coolant passage

Methodology Applied
Scientific EffectFluid circulation: Pump

Implementation Method 2

When the temperature of the coolant is low, e.g., at start-up of the engine, the thermostat opens the bypass passage. When the engine is warmed, the temperature of the coolant increases, and the thermostat closes the bypass passage

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

a radiator arranged forward relative to the cylinder body; the coolant is cooled through the radiator

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 4

an internal combustion engine including a crankcase having a side wall, a cylinder body connected to the crankcase, and a cylinder head connected to the cylinder body

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3904654B1Straddled vehicle
Publication Date: 2022.10.26 YAMAHA MOTOR CO LTD
  • EP3904654B1 patent drawingFigure 1
  • EP3904654B1 patent drawingFigure 2
  • EP3904654B1 patent drawingFigure 3

AI summary

A motorcycle 1 includes a water pump 20 attached to a side wall 31a of a crankcase 31, and a thermostat 50 arranged forward of a cylinder body 32 and rearward relative to a radiator 40. The water pump 20 includes an inlet 20i and an outlet 20o connected directly to a coolant passage 3W formed inside an internal combustion engine 3. An exhaust pipe 10 includes an exhaust pipe portion 19 that is located between a front end 20F and a rear end 20Re of the water pump 20 and that has an upper edge 19u located upward relative to a lower end 20D of the water pump 20 as the vehicle is seen from the side. The thermostat 50 is arranged inward relative to the exhaust pipe portion 19 in a vehicle width direction.