Compact Throttle Device with Overlapping Return Spring

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Solution Overview

Problem

Conventional throttle devices are too large, making them difficult to mount on straddled vehicles due to their extended size, particularly in the direction of the throttle shaft.

Innovation Solution

A compact throttle device design featuring a throttle body, throttle shaft, throttle valve, a first shaft parallel to the throttle shaft, a transmission mechanism to transmit rotational force, and a return spring positioned on the first shaft to bias the throttle valve, allowing for a more compact configuration without increasing the device's size in the extending direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the return spring is provided on the throttle shaft extension, then the return spring can directly bias the throttle valve, but the throttle device length increases making it difficult to mount on straddled vehicles

Engineering Contradiction:
Improvereturn spring mounting simplicityVSAvoidthrottle device length
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The patent applies dimensional repositioning by moving the return spring from the axial direction (throttle shaft extension) to a radial/overlapping position. The return spring is now provided on a first shaft that overlaps with the throttle shaft in the extending direction, changing the spatial arrangement from linear extension to overlapping configuration. This dimensional change reduces the overall device length while maintaining the return spring's functional capability to bias the throttle valve through the transmission mechanism.

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

Solution Approach 2:

The patent implements nesting by positioning the return spring within the spatial envelope of the throttle shaft assembly. The return spring is arranged to overlap with the throttle shaft in the extending direction, effectively nesting the return spring's functional space within the existing throttle shaft volume. This nested arrangement eliminates the need for axial extension while preserving the return spring's biasing function through the transmission mechanism to the throttle valve.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Length of moving object

If the throttle shaft is shortened to reduce device size, then the throttle device becomes more compact, but the return spring cannot be directly mounted on the throttle shaft

Engineering Contradiction:
Improvethrottle shaft lengthVSAvoidreturn spring mounting
Core Design Contradiction:
Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent introduces a first shaft as an intermediary element between the return spring and the throttle valve. This first shaft serves as a mediator that receives the return spring and transmits its rotational force to the throttle valve through the transmission mechanism. The intermediary first shaft enables the return spring to be mounted in an overlapping position rather than on the throttle shaft itself, allowing both compact dimensions and proper return spring functionality to coexist.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the functional roles by separating the return spring mounting function from the throttle shaft. The throttle shaft is dedicated to direct coupling with the throttle valve, while a separate first shaft handles the return spring mounting and force transmission. This functional segmentation allows the throttle shaft to be shortened without compromising return spring mounting capability, as the return spring is now mounted on the separate first shaft that overlaps with the throttle shaft.

Inventive Principle:
Principle #1Segmentation

3Volume of moving object

If a transmission mechanism is added to transmit rotational force between throttle shaft and first shaft, then the return spring can be positioned on the first shaft, but the device complexity increases

Engineering Contradiction:
Improvethrottle device compactnessVSAvoidtransmission mechanism complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The transmission mechanism is designed with multi-functionality to justify its inclusion. It not only transmits rotational force from the first shaft to the throttle shaft but also enables the return spring to be positioned in an overlapping configuration, achieves compact device dimensions, and facilitates the separation of return spring mounting from throttle shaft extension. The transmission mechanism serves multiple purposes: force transmission, spatial configuration enablement, and compactness achievement, making the added complexity worthwhile.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4484735A1Throttle device and straddled vehicle including the same
Publication Date: 2025.01.01 YAMAHA MOTOR CO LTD
  • EP4484735A1 patent drawingFigure 1
  • EP4484735A1 patent drawingFigure 2~3
  • EP4484735A1 patent drawingFigure 4~5

AI summary

There is disclosed a small throttle device (10, 70) and a straddled vehicle (1) including the same., wherein a throttle device (10) includes a throttle body (11), a throttle shaft (21), throttle valves (12a and 12b), a first shaft, a transmission mechanism, and a return spring 35; the throttle body (11) having the intake passages (V); the throttle shaft (21)being supported by the throttle body (11); the throttle valves (12a and 12b) being provided in the intake passages (V); the throttle valves (12a and 12b) beingcoupled to the throttle shaft (21); the drive shaft (22) being parallel with the throttle shaft (21); the transmission mechanism (9) transmitting a rotational force between the throttle shaft (21) and the drive shaft (22); the return spring (35) being provided on the drive shaft (22); the return spring (35) biasing the throttle valves (12a and 12b) in the closing direction via the transmission mechanism (9).