Cam Clutch Switching Geometry for Stable, Fast Engagement
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Solution Overview
Problem
Existing two-way clutches experience poor responsiveness due to time lost when switching rotation direction and variations in cam position and attitude, leading to inconsistent operation timing.
Innovation Solution
A cam clutch design that restricts the circumferential position and attitude of cams, allowing for consistent engagement and disengagement, with a larger moment arm for easier attitude change, enhancing stability and responsiveness without increasing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sprags are tilted in the same direction as rotation direction to switch engagement states, then the clutch can transmit and interrupt rotary force, but responsiveness deteriorates due to time lost when rotation direction is switched
Solution Approach 1:
Instead of tilting sprags in the rotation direction, the invention uses cams that are tilted in the opposite direction to the rotation direction. This inversion allows the cam's large surface area to engage with the sprag, enabling rapid state switching without the time loss associated with traditional sprag tilting mechanisms.
Solution Approach 2:
The invention introduces a new dimensional approach by using the cam's large surface area (area dimension) to engage with the sprag, rather than relying solely on the linear tilting motion of sprags. This dimensional change enables more effective force transmission and faster response during state switching.
2Device complexity
If multiple cams are circumferentially equally spaced in retainer pockets, then the clutch structure is simplified, but cam position and attitude variations occur leading to inconsistent operation timing
Solution Approach 1:
The cam is designed with pre-established geometric features (large surface area, specific tilt angle) that predetermined the engagement characteristics. This preliminary design ensures that even with manufacturing variations, the cam maintains consistent operational timing because the engagement is governed by the cam's inherent geometry rather than precise positioning.
Solution Approach 2:
The invention changes the critical parameter from cam position (which is difficult to control precisely) to cam surface area and tilt angle (which can be manufactured with greater consistency). By making the cam surface area sufficiently large and establishing a specific tilt angle, the system becomes less sensitive to manufacturing variations in cam positioning.
3Reliability
If cam surface area is increased to improve engagement stability, then operational consistency improves, but the moment arm increases requiring larger switching forces
Solution Approach 1:
The cam is designed with asymmetric geometry, featuring a large surface area on one side for stable engagement with the sprag, while the other side maintains a more compact form. This asymmetry allows the cam to provide stable engagement during normal operation while minimizing the moment arm and switching force requirements.
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
The cam clutch achieves improved stability and high responsiveness by ensuring consistent cam behavior and reducing the influence of production variations, allowing for smooth switching among multiple operating modes.
Implementation Method 1
a biasing means that biases each cam to make contact with the inner race and the outer race
Implementation Method 2
a cam attitude change part that tilts each cam when operated, and in which a load application point for applying a load to tilt each cam is positioned on the circumferential side of a load support point for supporting a load reaction
Data Source
Figure 1
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AI summary
An object of the present invention is to provide a cam clutch capable of switching from one operating mode to another and offering improved stability of clutch operations and high responsiveness. The object is achieved by an operating mode switching means (180) having a cam attitude change part (185) that forcibly tilts each of a plurality of cams (140) biased by a biasing means to make contact with an inner race (110) and an outer race (120) and being drivable independently of rotation of the inner race (110) and outer race (120). A load support point (Sp) is located radially between a load application point (Ap) of the cam attitude change part (185) on the cam (140) and a distal contact point (Ep) of the cam (140) on a raceway positioned on a radially distal side relative to the load application point (Ap). The radial distance (d1) between the load application point (Ap) and the load support point (Sp) is larger than the radial distance (d2) between the load support point (Sp) and the distal contact point (Ep).