Electric Actuator Slip Clutch Torque Protection
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Solution Overview
Problem
Existing electric actuators for drive apparatuses with rotatable control shafts face challenges in providing precise control and protection against excessive torque, leading to potential damage to components, especially in applications like transaxles where shared oil systems can complicate component integration and protection.
Innovation Solution
An electric actuator with a rotary design featuring a position sensor, a reduction gear train with a worm drive and spur gear reduction, and a slip clutch to limit torque, integrated with a motor chamber and housing that can share oil with hydraulic components, ensuring precise control and protection against excessive torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reduction gear train with worm drive is used to position the control shaft, then precise control is achieved, but the components are vulnerable to excessive torque damage
Solution Approach 1:
A slip clutch is disposed between the worm drive and spur gear reduction to protect the components of the reduction gear train. The slip clutch is configured to slip when excessive torque is applied, preventing damage to the reduction gear train components while allowing precise control operation under normal conditions.
2Device complexity
If the electric actuator housing is integrated with the transaxle housing to share oil, then the need for separate housing elements is reduced, but the complexity of integration and protection increases
Solution Approach 1:
The housing of the electric actuator features a motor chamber to accommodate the electric motor and is sealed by a cap having an electric connector. In certain applications, such as in use with a transaxle, the actuator housing may be integrated with the transaxle housing such that the gearing for the actuator and the hydraulic components of the pump or transaxle may share oil, to minimize the need for separate housing elements.
3Reliability
If a slip clutch is added to protect against excessive torque, then component protection is improved, but the device complexity increases
Solution Approach 1:
A slip clutch may be disposed between the worm drive and spur gear reduction to protect the components of the reduction gear train. The slip clutch acts as an intermediary protective element that engages only when excessive torque is detected, allowing precise control under normal operation while providing automatic protection when needed.
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 enables precise control adjustments and protects the components from excessive torque, ensuring reliable operation in applications like transaxles by integrating the electric actuator with the transaxle housing to share oil and reduce the need for separate housing elements, enhancing the overall efficiency and durability of the drive apparatus.
Implementation Method 1
An electric motor drives a reduction gear train to position the control shaft, the reduction gear train having a worm drive that motivates a spur gear reduction.
Implementation Method 2
A slip clutch may be disposed between the worm drive and spur gear reduction to protect the components of the reduction gear train, and to also place a limit on the torque applied to the control shaft.
Data Source
AI summary
An actuator has an actuator housing engaged to a portion of a transaxle housing to define a space. A clutch assembly has a support shaft extending through the actuator housing and rotatably supporting gears in the space. At least one pin extends through one gear and a spring urges the pin into engagement with a second gear. An adjustment nut extends through the actuator housing and engages the support shaft to adjustably compress the spring. The actuator may further have an actuator housing forming a motor chamber and a gear chamber. A mounting plate detachably couples the actuator and pump housings, and the plate defines an opening through which a pump control shaft extends. A worm drive is disposed in the gear chamber and driven by an electric motor shaft, and drives a spur gear reduction, the pump control shaft being controlled by the spur gear reduction.