Cam Mechanism with Counter Biasing for Fixing Device Stability
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Solution Overview
Problem
The existing cam mechanisms in fixing devices for image forming apparatuses experience noise, vibration, and varying motor load due to shifting of the pressing roller, which requires sufficient motor output for both acceleration and deceleration, and results in fluctuating input current.
Innovation Solution
A cam mechanism with an ascending region and a descending region shifted by 180 degrees, where the output object and counter object apply forces in opposite directions to maintain consistent load torque, reducing noise and vibration, and stabilizing motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a cam mechanism with a single biasing member is used to move the pressing roller, then the pressing roller can be moved in directions close to or away from the pressing roller to vary the pressure of the pressing area, but the cam may be shifted (jumping movement) by ratting of each member regardless of a driving force of the motor, causing noise and vibration
Solution Approach 1:
The patent introduces a counter biasing member that applies a force opposite to the main biasing member. This counter force balances the load torque on the cam, preventing the cam from shifting or jumping during operation. The counter biasing member acts as a counterweight that offsets the harmful ratting effects, thereby eliminating noise and vibration while maintaining pressure variation capability.
Solution Approach 2:
The counter biasing member is configured to apply a preliminary counteracting force before the harmful ratting effects can cause cam shifting. By anticipating and opposing the ratting forces through the counter biasing member, the system prevents the jumping movement from occurring in the first place, thereby preventing noise and vibration before they can manifest.
2Adaptability or versatility
If the radius of the cam is varied in the ascending region and the descending region, then the force applied to the cam from the biasing member is varied, but the motor rotating the cam is required to have sufficient output force for both acceleration and deceleration, and the input current for the motor increases and decreases during the rotating of the cam
Solution Approach 1:
The counter biasing member provides a counter force that balances the varying force from the main biasing member. This balancing action maintains consistent load torque on the cam throughout its rotation, allowing the motor to operate at a steady output level without needing excessive power capacity for acceleration and deceleration peaks.
Solution Approach 2:
The patent modifies the cam profile parameters in the ascending and descending regions to work in conjunction with the counter biasing member. By carefully designing the radius variations and positioning the counter biasing member 180 degrees opposite to the main biasing member, the system achieves consistent load torque while maintaining the necessary force application capability for pressure control.
3Device complexity
If a cam mechanism with a single biasing member is used, then the structure is simpler, but the motor is required to have capacity capable of withstanding the change of the input current during rotation
Solution Approach 1:
The counter biasing member is configured to exactly balance the load torque variations caused by the cam profile. This creates a stable operating condition where the motor experiences consistent loading, eliminating current fluctuations and improving motor reliability. The additional component is offset by the elimination of motor oversizing requirements.
Solution Approach 2:
The counter biasing member is integrated into the existing cam mechanism structure, sharing the same cam body and rotational axis. This merging approach minimizes the increase in device complexity while achieving the reliability benefits of stabilized motor operation. The counter biasing member utilizes the existing structural framework rather than requiring entirely separate systems.
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 solution reduces noise and vibration, stabilizes motor operation by maintaining consistent load torque, and decreases the maximum load on the motor, preventing current fluctuations, thus enhancing the operational stability of the fixing device.
Implementation Method 1
a cam to convert rotational motion output by a drive source, such as a motor, to linear motion is used
Implementation Method 2
the pressing roller abuts on the cam by a biasing member. Thereby, a direction of load torque applied to the cam by the biasing member is changed
Data Source
AI summary
A cam mechanism includes a cam, an output object and a counter object. The cam has a profile including an ascending region where a radius gradually increases along a rotating direction and a descending region where the radius gradually decreases along the rotating direction. The ascending region and the descending region are shifted each other by 180 degrees. The output object abuts on the cam with a predetermined pressure and linearly moves in an abutting direction in which the output object abuts on the cam and in a counter-abutting direction opposite to the abutting direction by rotating of the cam. The counter object abuts on the cam with the predetermined pressure from the counter-abutting direction at a position shifted by 180 degrees with respect to an abutting position between the output object and the cam.