Clutch Spring Coils for Selective Accessory Drive
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Solution Overview
Problem
Existing accessory drive systems in engine systems lack the ability to selectively apply engine-generated torque to accessories, making it difficult to operate or deactivate accessories like water pumps based on engine operating conditions, such as temperature.
Innovation Solution
A clutch assembly comprising a driver with a cylindrical torque transfer surface, a clutch spring with coils wound in opposition to the driver's rotational direction, an armature, and an actuator that allows for selective engagement and disengagement of the clutch, enabling controlled transmission of rotary power between the driver and output member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If accessories are directly connected to the engine crankshaft via drive means, then accessories are continuously operated when the engine is running, but fuel efficiency deteriorates because accessories cannot be selectively deactivated when not needed
Solution Approach 1:
The clutch assembly enables dynamic engagement and disengagement of the accessory drive system. The spring coils can dynamically transition between engaged and disengaged states based on actuator activation, allowing the system to adapt to varying operational requirements and selectively operate accessories based on engine conditions such as temperature.
Solution Approach 2:
The clutch assembly segments the direct connection between the engine crankshaft and the accessory. By introducing a controllable clutch mechanism with spring coils that can be engaged or disengaged, the system separates the continuous engine operation from the conditional accessory operation, enabling selective deactivation to improve fuel efficiency.
2Loss of energy
If a clutch mechanism is introduced to enable selective operation of accessories, then fuel efficiency improves, but device complexity increases due to additional components
Solution Approach 1:
The clutch mechanism utilizes flexible spring coils that can engage and disengage through elastic deformation. This flexible element approach reduces the need for complex rigid mechanical components, simplifying the overall clutch assembly while maintaining the selective engagement capability needed for fuel efficiency improvements.
Solution Approach 2:
The clutch assembly replaces complex multi-component mechanical engagement systems with a simpler spring-based mechanism. The spring coils provide both the engagement force and the disengagement capability through elastic properties, reducing the number of separate mechanical parts needed compared to traditional clutch designs.
3Ease of operation
If the clutch spring coils are wound in the same direction as driver rotation, then engagement is simpler, but disengagement control becomes difficult
Solution Approach 1:
The spring coils are wound in the opposite direction to the driver rotation. This inversion creates a mechanical advantage where the rotational motion of the driver naturally tends to disengage the coils, while the actuator provides the controlled force needed for engagement. This reverse winding direction simplifies disengagement control while maintaining ease of operation.
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
Enables selective operation of accessories by allowing controlled transmission and limitation of rotary power, improving fuel efficiency by allowing accessories to be operated only when necessary, such as after the engine reaches a preselected temperature.
Implementation Method 1
A force is generated when the actuator is operated in the disengaging mode that is applied to the armature such that the armature rotates relative to the driver
Implementation Method 2
Rotation of the driver in the predetermined direction when the actuator is operated in the engaging mode causes the coils of the clutch spring to drivingly engage the cylindrical torque transfer surface such that rotary power is transmitted
Data Source
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AI summary
A clutch assembly having a driver, an output member, a clutch spring, an armature and an actuator. The clutch spring includes a plurality of coils that are configured to be drivingly engaged with the driver. The clutch spring further includes first and second control tangs. The first control tang is configured to drivingly engage the output member to facilitate the transmission of rotary power from the driver, through the clutch spring and into the output member. The second control tang is engaged to the armature. The actuator is selectively operable for rotating the armature relative to the driver in a rotational direction opposite a predetermined rotational direction in which the driver is driven to thereby initiate at least partial disengagement of the coils of the clutch spring from the driver.