Throttle Bore Groove Structure for Easier Valve Assembly

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Solution Overview

Problem

The assembly of throttle valves in throttle devices is difficult due to the maximum diameter portion of the throttle valve contacting the inner surface of the bore, especially when the flow-path cross-sectional area decreases, and existing solutions to facilitate assembly increase flow path resistance.

Innovation Solution

The throttle device incorporates grooves on the inner surface of the bore that allow the throttle valve to be assembled from the second end surface, with protrusions from the intake part fitting into these grooves to suppress flow path resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a valve insertion groove is provided on the inner surface of the bore to facilitate assembly, then the assembly of the throttle valve becomes easier, but the valve insertion groove increases the flow path resistance in the bore

Engineering Contradiction:

Improveassembly easeVSAvoidflow path resistance

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The solution divides the groove structure into multiple segments: guide grooves for assembly facilitation and protrusions for flow path restoration. This segmentation allows the groove to serve its assembly function while minimizing its negative impact on flow characteristics by closing it off with protrusions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The groove is provided only in specific local areas where assembly guidance is needed, rather than across the entire bore surface. The protrusions then locally restore the flow path by closing these grooves, ensuring that the flow path resistance increase is minimized while still providing assembly assistance where required.

Inventive Principle:

Principle #3Local quality

2Shape

If the flow-path cross-sectional area decreases from the first open end to the second open end of the bore, then the throttle device structure is optimized, but it becomes difficult to assemble the throttle valve from the second open end

Engineering Contradiction:

Improveflow path configurationVSAvoidassembly ease

Core Design Contradiction:

ShapeVSEase of operation

Solution Approach 1:

The guide grooves are pre-formed on the inner surface of the bore before assembly, creating a predetermined path that guides the throttle valve during insertion. This preliminary preparation of the assembly path allows the valve to be easily inserted from the second open end despite the decreasing flow-path cross-sectional area.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4230857B1Throttle device and intake assembly

Publication Date: 2026.02.04 MIKUNI CORP

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AI summary

A throttle device 10 includes: a throttle body 20 having a bore 12 opening to a first end surface 21 and a second end surface 22; a throttle shaft 40 disposed rotatably within the bore 12; and a throttle valve 50 fixed to the throttle shaft 40 so as to be located at least partially within the bore 12. The bore 12 has an inner surface defining an intake flow path 13 that decreases in flow-path cross-sectional area at least partially from a first open end 14 to a second open end 16 of the bore. The inner surface of the bore 12 has: a pair of through holes 18 through which the throttle shaft 40 passes; and a pair of grooves 24 that run from each of the through holes 18 to an edge of the second open end 16.