Water Jacket Spacer Contact Mechanism for Engine Bore Cooling

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Solution Overview

Problem

Conventional water jacket spacers in engines suffer from undesired changes in spacing from the cylinder bore wall due to deformation or vibration, leading to inadequate cooling of the bore upper part, which can result in increased temperature and potential engine damage.

Innovation Solution

A water jacket spacer with an upper wall part closer to the inner wall surface and a lower wall part closer to the outer wall surface, featuring an elongated contact member that changes posture from separated to contacting the outer wall surface based on coolant temperature, ensuring high workability during assembly and effective cooling during operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the water jacket spacer is inserted into the water jacket during engine assembly, then the spacer can be positioned to adjust cylinder bore temperature, but the spacer may deform or vibrate causing undesired changes in spacing from the cylinder bore wall

Engineering Contradiction:
Improvespacing stabilityVSAvoidspacer deformation
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The contact member is designed to dynamically change its posture between a first state (separated from outer wall surface) and a second state (contacting outer wall surface) based on operating conditions. This dynamic adaptation allows the spacer to maintain stable spacing during operation while facilitating easy insertion during assembly, resolving the contradiction between reliability and stability.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the contact member is in contact with the outer wall surface during assembly, then the spacer body member may be deformed, but if the contact member is separated during operation, then sufficient cooling of the bore upper part cannot be achieved

Engineering Contradiction:
Improvecooling effectivenessVSAvoidspacer body deformation
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The contact member transitions from a separated first state during assembly to a contacting second state during operation. This dynamic posture change ensures that the spacer body member is not deformed during assembly while achieving sufficient cooling of the bore upper part during operation through enhanced heat transfer via the contact member.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The contact member is pre-configured to be separable from the outer wall surface during assembly, preventing deformation before the spacer is installed. After installation and during operation, the contact member then makes contact to provide the necessary cooling function, embodying preliminary action to avoid harm before it occurs.

Inventive Principle:
Principle #10Preliminary action

3Temperature

If the channel width of the water jacket is made wider in the bore upper part section, then cooling of the bore upper part can be improved, but the water jacket spacer requires larger dimensions making insertion difficult

Engineering Contradiction:
Improvebore upper part temperatureVSAvoidspacer insertion difficulty
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The spacer is segmented into an upper wall part and a lower wall part, with the contact member providing additional cooling function. This segmentation allows the spacer to maintain a compact overall size for easy insertion while the contact member specifically addresses the cooling requirement of the bore upper part through direct thermal contact.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The contact member is specifically positioned to contact the outer wall surface in the bore upper part region, providing localized enhanced heat transfer where it is most needed. This local quality enhancement achieves improved cooling of the bore upper part without requiring the entire spacer to be enlarged.

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

Prevents deformation of the spacer body member due to vibration or temperature changes, enhances heat transfer to coolant, and improves thermal efficiency by preventing knocking and degradation of engine performance.

Implementation Method 1

having a higher heat conductivity than the spacer body member and the wall of the cylinder bore

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

an expandable member changeable between a state where the expandable member is contracted or shrunk to bring the contact member into the first posture, and a state where the expandable member is extended or expanded to bring the contact member into the second posture

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4579073A1Water jacket spacer and engine
Publication Date: 2025.07.02 MAZDA MOTOR CORP
  • EP4579073A1 patent drawingFigure 1
  • EP4579073A1 patent drawingFigure 2
  • EP4579073A1 patent drawingFigure 3

AI summary

A water jacket spacer inserted into a water jacket between an outer wall surface of a cylinder bore wall of an engine and an inner wall surface of a cylinder block includes a spacer body member including upper and lower wall parts which are closer to the inner and outer wall surfaces in upper and lower parts of the water jacket, respectively, and an elongated contact member fixed at one end to the upper wall part, changeable between first and second postures where it is separated from and contacts with the outer wall surface, respectively. The contact member is in the first posture when coolant is not filled in the water jacket and the engine is not operated, and is in the second posture when the coolant is filled in the water jacket and the engine is operated.