Engine Throttle Device Axial Positioning via Fixing Nut
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Solution Overview
Problem
Existing engine throttle devices face challenges in reducing the external dimension of the throttle shaft in the axial direction while ensuring smooth opening and closing of the throttle valve with proper positioning of the throttle shaft.
Innovation Solution
The engine throttle device incorporates a gear case with gear trains, a bearing system with an outer ring fitted to an annular fitting portion and an inner ring fitted to the throttle shaft, and a positioning ring that restricts displacement of the outer ring along the axis, allowing for reduced external dimensions and improved positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a compression spring is used to bias the inner ring of the bearing to position the throttle shaft in the axial direction, then the positioning effect is improved, but the external dimension of the throttle device increases in the axial direction
Solution Approach 1:
The invention extracts and eliminates the compression spring from the bearing support structure. Instead of using a spring to bias the inner ring, the patent uses a fixing nut to directly secure the inner ring against a shoulder on the throttle shaft, thereby removing the axial space required for spring compression while maintaining positioning functionality.
Solution Approach 2:
The invention introduces a fixing nut as an intermediary component between the inner ring and the throttle shaft. This nut provides a direct mechanical means to secure the inner ring in the axial direction, replacing the spring-based biasing mechanism and achieving positioning without increasing external dimensions.
2Manufacturing precision
If the outer ring is fixedly positioned in the axial direction through press-fitting in the annular fitting portion, then the displacement restriction is improved, but the press-fitting may allow the outer ring to move in the axial direction under external force
Solution Approach 1:
The invention applies preliminary action by pre-tightening the fixing nut to securely clamp the inner ring against the shoulder before any external forces act on the system. This preliminary securing action ensures that the inner ring and consequently the outer ring remain firmly positioned, preventing any potential movement under operational loads.
Solution Approach 2:
The invention utilizes the spherical geometry of the bearing balls to transmit and distribute forces uniformly between the inner and outer rings. The ball bearing configuration ensures that axial forces are evenly distributed across the contact surfaces, enhancing the reliability of the positioning system by preventing localized stress concentrations that could cause movement.
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 reduces the external dimension of the throttle shaft in the axial direction, enables smooth operation of the throttle valve, and maintains the throttle shaft's axial positioning without the need for a compression spring, thereby enhancing mountability and reliability.
Implementation Method 1
a positioning ring pressure-fitted into the annular fitting portion and abutting the outer ring to restrict displacement of the outer ring along an axis of the throttle shaft
Implementation Method 2
a fixing nut screwed onto the one end of the throttle shaft inside the gear case and abutting the inner ring on one end side to restrict displacement of the inner ring and the one end side
Implementation Method 3
a bearing having an outer ring fitted to the annular fitting portion and an inner ring fitted to the throttle shaft, and rotatably supporting the throttle shaft
Data Source
AI summary
An engine throttle device 1 includes: a throttle shaft 4 supporting a throttle valve 7 inside a throttle bore of a throttle body 2 such that the throttle valve 7 is able to be opened and closed; and a gear case 18 fixed to a side portion of the throttle body 2 and accommodating gear trains, causes one end of the throttle shaft 4 to project into the gear case 18 via shaft holes 20 and 21, and drives the throttle shaft 4 via the gear trains 22, 26, and 29. The throttle device 1 further includes: an annular fitting portion 42 formed to be adjacent to the shaft hole 21; a bearing 6 having an outer ring 6b fitted to the annular fitting portion 42 and an inner ring 6a fitted to the throttle shaft 4, and rotatably supporting the throttle shaft 4; a positioning ring 45 press-fitted into the annular fitting portion 42 and abutting the outer ring 6b to restrict displacement of the outer ring 6b along an axis C of the throttle shaft 4; and a fixing nut 39 screwed onto one end of the throttle shaft 4 inside the gear case 18 and abutting the inner ring 6a on one end side to restrict displacement.