Ratchet Mechanism Torque Direction Control
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Solution Overview
Problem
Existing fixing devices for image forming apparatuses require a mechanism to selectively transmit torque to either the fixing roller or the pressure adjustment mechanism, often using expensive one-way clutches, and there is a need for a cost-effective alternative that also reduces noise and saves space.
Innovation Solution
A fixing device incorporating a ratchet mechanism and a transmission mechanism, where the drive input gear device receives torque in specific directions to transmit it to either the fixing roller or the pressure adjustment mechanism, allowing for posture changes in nip pressure and reducing torque transmission to the fixing roller when necessary, thereby using a ratchet mechanism for directional torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a one-way clutch is used to selectively transmit torque to the fixing roller or pressure adjustment mechanism, then the torque transmission control is achieved, but the device cost increases
Solution Approach 1:
The patent replaces the expensive one-way clutch with a ratchet mechanism that uses simple, inexpensive components such as ratchet teeth formed directly on gears and a lightweight spring. This achieves the same torque directionality function at much lower cost, making the torque transmission control mechanism more economically viable for mass production
Solution Approach 2:
The patent substitutes the complex one-way clutch mechanical system with a simpler ratchet and pawl mechanism that achieves identical functional results. The ratchet teeth on gears配合with a simple spring-loaded pawl provide the necessary unidirectional torque transmission without requiring the more complex and expensive one-way clutch assembly
2Ease of operation
If a one-way clutch is used for directional torque transmission, then the torque control function is achieved, but the device size increases
Solution Approach 1:
The patent integrates the ratchet mechanism components within the existing gear structure by forming ratchet teeth directly on the gear peripheries. The spring-loaded pawl is positioned within the gear housing space, nesting multiple functional elements into a compact arrangement that achieves torque directionality without increasing overall device volume
Solution Approach 2:
The patent combines the torque transmission gear and the ratchet mechanism into a single integrated assembly. The ratchet teeth are formed on the gear itself rather than being separate components, and the spring mechanism is incorporated into the same housing space, merging multiple functions into a compact unified structure that maintains small device size
3Ease of operation
If a one-way clutch is used to manage torque direction, then the torque transmission is controlled, but the operating noise increases
Solution Approach 1:
The patent replaces the noisy one-way clutch with a simple ratchet mechanism using basic components like spring-loaded pawls and gear teeth that engage quietly. This eliminates the high-pitched noise and mechanical harshness associated with one-way clutches while maintaining torque directionality control
Solution Approach 2:
The patent substitutes the one-way clutch mechanical system with a ratchet and spring mechanism that provides smoother, quieter operation. The spring-loaded pawl engages with ratchet teeth in a controlled manner that reduces impact noise and vibration, eliminating the harmful noise generated by the one-way clutch
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 allows for efficient and cost-effective directional torque transmission, reduces noise, and saves space by using a ratchet mechanism to manage torque directionally, enabling effective nip pressure adjustment without the need for expensive one-way clutches.
Implementation Method 1
the ratchet mechanism transmits the torque of the first rotational direction to the first roller, and when the drive input gear device receives the torque of the second rotational direction, the ratchet mechanism suspends a torque transmission to the first roller
Implementation Method 2
the transmission mechanism exerts a driving force to the pressure adjustment mechanism to thereby allow the posture change
Data Source
AI summary
A fixing device includes first and second rollers, a pressure adjustment mechanism, a drive input gear, a ratchet mechanism, and a transmission mechanism. The pressure adjustment mechanism changes a pressing posture of the first and second rollers. The drive input gear device receives a torque of a first rotational direction around an axis of the gear device and another toque of a second rotational direction. The ratchet mechanism, when the drive input gear device receives the torque of the first rotational direction, transmits the torque to the first roller, and in the case of the torque of the second rotational direction, suspends a torque transmission. When the drive input gear device receives the torque of the second rotational direction, the transmission mechanism exerts a driving force to the pressure adjustment mechanism. The drive input gear device includes a housing portion housing a part of the ratchet mechanism.