Electro-Hydraulic Lead Screw Actuator for Precision Under Heavy Loads
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Solution Overview
Problem
Existing heavy-duty machinery requires more maintenance and is not suitable for harsh environments and high loads, as electric linear actuators lack the power density and shock resistance of hydraulic cylinders, while hydraulic cylinders are not precise enough.
Innovation Solution
An electro-hydraulic linear lead screw actuator combining an electric motor, hydraulic tube, ball screw, ball nut device, and external hydraulic flow passages, which uses hydraulic fluid for load support and precision location, allowing for high precision movement and reduced maintenance in hostile environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electric linear actuators are used, then precision and speed are improved, but power density and shock resistance deteriorate
Solution Approach 1:
The patent combines an electric motor with a hydraulic system into a single integrated actuator. The electric motor drives a hydraulic pump that pressurizes fluid to move a piston, merging the precision control of electric actuators with the high power density of hydraulic systems. This hybrid approach allows the device to achieve both precise movement and high power output.
Solution Approach 2:
The patent introduces hydraulic fluid as an intermediary between the electric motor and the linear motion output. The electric motor rotates a hydraulic pump, which pressurizes the fluid to drive the piston rod. This intermediary hydraulic system enables the transmission of high power while maintaining precise control through the electric motor's regulated operation.
2Reliability
If electric linear actuators are used, then maintenance requirements are reduced, but shock resistance and heavy load handling deteriorate
Solution Approach 1:
The patent merges the low-maintenance electric motor with a robust hydraulic system designed to handle shocks and heavy loads. The hydraulic components, including the piston, rod, and fluid-filled chamber, are constructed to withstand high impact forces, while the electric motor provides reliable, maintenance-free operation for precise control.
Solution Approach 2:
The patent applies different quality characteristics to different parts of the system. The electric motor portion is designed for precision and low maintenance, while the hydraulic portion (piston, rod, fluid chamber) is designed for shock resistance and heavy load handling. Each component is optimized for its specific function within the hybrid system.
3Power
If hydraulic cylinders are used, then power density and shock resistance are improved, but measurement precision deteriorates
Solution Approach 1:
The patent uses the electric motor as an intermediary control device that regulates the hydraulic system's operation. The electric motor's precise rotational control translates to precise hydraulic pressure control, enabling the high-power hydraulic system to achieve fine movement precision through the electric motor's regulated pump operation.
Solution Approach 2:
The patent implements feedback control where the electric motor's operation is regulated based on desired position or force requirements. This feedback mechanism allows the hydraulic system to achieve precise movement by continuously adjusting the electric motor's rotation speed and direction, thereby controlling hydraulic pressure and piston position with high accuracy.
4Strength
If hydraulic cylinders are used, then heavy load handling is improved, but maintenance requirements increase
Solution Approach 1:
The patent combines the heavy load handling capability of hydraulic cylinders with the low maintenance requirements of electric motors. The hydraulic system handles the heavy loads through high-pressure fluid acting on the piston, while the electric motor provides reliable, sealed operation with fewer maintenance points, reducing overall system maintenance needs compared to traditional hydraulic cylinders.
Solution Approach 2:
The patent incorporates self-lubricating features and sealed hydraulic components that reduce maintenance requirements. The electric motor's sealed construction prevents contamination, and the hydraulic system is designed with minimal service points, allowing the heavy-duty actuator to operate with reduced maintenance compared to conventional hydraulic cylinders.
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 electro-hydraulic linear lead screw actuator provides high precision movement and supports large loads with reduced maintenance requirements, operating effectively in hostile environments by utilizing hydraulic fluid for load support and precision location.
Implementation Method 1
The ball nut device includes a ball nut base, a piston portion and a rod thread. The ball nut base includes a plurality of ball bearings, a ball bearing loop and an actuator ball screw opening.
Implementation Method 2
Support for a load on the end of the actuator rod is mainly supported by hydraulic fluid, not the actuator ball screw and ball nut device.
Implementation Method 3
One end of the actuator ball screw is rotatably retained in the first end cap. A ball thread is formed on an outer perimeter of the actuator ball screw.
Data Source
AI summary
An electro-hydraulic linear lead screw actuator preferably includes an electric motor device, a hydraulic tube, an actuator lead screw, an actuator screw nut, an actuator rod and at least one external hydraulic flow passage. The actuator lead screw is rotated by the electric motor device. The actuator screw nut preferably includes a piston portion, a first screw nut portion and a second screw nut portion. A lead screw thread is formed through the first and second screw nut portions to threadably receive the actuator lead screw. The actuator rod is retained on the piston portion. Rotation of the electric motor device causes the actuator rod to extend or retract. A first hydraulic chamber is located behind the piston portion and a second hydraulic chamber is located in front of the piston portion. At least one external hydraulic flow passage transfers hydraulic fluid between the first and second chambers.