Engine Timer Centrifugal Weights Shape Memory Spring
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Solution Overview
Problem
Conventional engine timers experience high transmission resistance and size issues due to the use of tapered cams, leading to reduced accuracy and durability, and require large, high-output components.
Innovation Solution
The engine timer employs an eccentric cam mechanism and a shape memory spring positioned concentrically with the weight-return spring, eliminating the need for a tapered cam and allowing for direct spring force application to centrifugal weights, enabling a compact design with reduced resistance and lower output requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tapered cam is used to transmit force from the advancing spring to the centrifugal weights, then the transmission path is established, but the friction of the tapered cam enlarges the resistance and lowers accuracy
Solution Approach 1:
The patent removes the tapered cam from the force transmission path. Instead of using a tapered cam to transmit force from the advancing spring to the centrifugal weights, the invention directly connects the advancing spring to the centrifugal weights, eliminating the intermediate component that caused friction and energy loss. This extraction of the problematic element directly resolves the contradiction between transmission accuracy and energy loss.
Solution Approach 2:
The patent introduces a new intermediary mechanism - a groove-and-ridge structure where the advancing spring engages with the centrifugal weights through a groove in the weight and a corresponding ridge on the spring. This new intermediary provides a low-friction transmission path that maintains force transfer efficiency while eliminating the high resistance caused by the tapered cam's friction.
2Reliability
If the wax and advancing spring are placed perpendicular to the weight-return spring along the rotary shaft axis, then the temperature-sensing operation is enabled, but the timer becomes elongated and large
Solution Approach 1:
The patent repositions the advancing spring and wax temperature-sensing element from an axial arrangement (perpendicular to the weight-return spring along the shaft axis) to a radial arrangement (concentric with the weight-return spring). This dimensional change from axial to radial positioning allows the temperature-sensing function to be maintained while significantly reducing the timer's axial length and overall size.
Solution Approach 2:
The patent nests the advancing spring and wax temperature-sensing element concentrically within the space occupied by or adjacent to the weight-return spring's radial position. This nesting arrangement allows multiple components to occupy overlapping spatial zones, enabling the temperature-sensing function without increasing the timer's external dimensions, particularly its axial length.
3Force
If large, high-output advancing spring and temperature-sensing means are used, then the transmission resistance is overcome, but the timer size increases
Solution Approach 1:
By removing the tapered cam from the transmission path, the patent eliminates the source of high friction resistance. This allows the use of a smaller, lower-output advancing spring because the resistance it must overcome is significantly reduced. The extraction of the problematic intermediate component enables downsizing of the force-generating elements.
Solution Approach 2:
The new groove-and-ridge intermediary mechanism provides efficient force transmission with minimal friction. This low-resistance transmission path allows smaller springs to generate sufficient force to advance the centrifugal weights, thereby enabling compact timer design without sacrificing the necessary advancing force.
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 enhances the accuracy of engine advancement during cold starts, improves exhaust-gas properties when warm, and maintains durability by minimizing wear and allowing for smaller, lower-output components.
Implementation Method 1
The advancing spring (6) is interlockingly connected to a temperature-sensing operation means (7)... When starting the engine during a cold term, the advancing spring (6) is maintained extensible based on a state of the temperature-sensing operation means (7) in which the temperature-sensing operation means (7) senses a temperature to operate
Implementation Method 2
A force of unbalance between the centrifugal force of each of the centrifugal weights (3) and the urging force of the weight-return spring (5) operates each of the centrifugal weights (3)... While each of the weights (3) is moved in a centrifugal direction, thereby advancing the driven wheel (2) with respect to the driving wheel (1) through the eccentric cam mechanism (4)
Implementation Method 3
There is provided between the driving wheel (1) and the driven wheel (2) an eccentric cam mechanism (4), which is interlockingly connected to the pair of centrifugal weights (3, 3)... While each of the weights (3) is moved in a centrifugal direction, thereby advancing the driven wheel (2) with respect to the driving wheel (1) through the eccentric cam mechanism (4)
Implementation Method 4
Each of the centrifugal weights (3) is urged in a centripetal direction by a weight-return spring (5) composed of a compression coil spring... moved in a centripetal direction, thereby allowing the driven wheel (2) to lag with respect to the driving wheel (1) through the eccentric cam mechanism (4)
Data Source
AI summary
Each of paired centrifugal weights are interlockingly connected to an advancing spring, which is interlockingly connected to a temperature-sensing operation device. When cold-starting the engine, the advancing spring is maintained extensible based on a state of the temperature-sensing operation in which the temperature-sensing operation device senses a temperature to operate. This advancing spring exerts a spring force, which pushes and widens the paired centrifugal weights to an advancing position. While the engine is warm, the advancing spring is held contracted based on another state of the temperature-sensing operation device, in which the temperature-sensing operation device senses a temperature to operate, so that the spring force of the advancing spring does not act on the paired centrifugal weights. A shape memory spring composed of a compression coil spring is used for the temperature-sensing operation device.