Electro-hydraulic Actuator Motor Placement for Maintenance
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Solution Overview
Problem
Existing electrohydraulic actuators are bulky and difficult to maintain due to the placement of the electric motor and pump on the side of the cylinder, with complex motor replacement procedures when failures occur.
Innovation Solution
The electric motor is placed at the end of the actuator, driving a non-circular splined shaft that rotates a pump integrated within the piston, allowing for easy dismantling in case of failure while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electric motor and pump are placed on the side of the cylinder, then the actuator structure is simple, but the actuator becomes bulky and motor replacement becomes complex
Solution Approach 1:
The actuator is divided into separable modules: the motor assembly can be independently removed from the cylinder body through the open end, while the pump remains integrated in the piston. This segmentation allows the motor to be replaced without disassembling the entire actuator or removing the piston, resolving the contradiction between compact integration and ease of motor repair.
2Volume of moving object
If the pump is integrated inside the piston, then the actuator becomes compact, but motor failure makes replacement complex requiring complete disassembly
Solution Approach 1:
The motor is extracted from the integrated configuration and positioned externally at the open end of the cylinder. This allows the motor to be taken out and replaced independently when failed, without requiring complete disassembly of the actuator or removal of the pump from the piston, thus maintaining compactness while simplifying maintenance.
3Ease of repair
If the motor is placed at the end of the actuator, then motor dismantling becomes easy, but the drive mechanism becomes more complex
Solution Approach 1:
A drive shaft serves as an intermediary element connecting the motor at the open end to the pump in the piston. This simple mechanical intermediary transmits rotational motion from the motor to the pump through the cylinder, enabling easy motor removal while avoiding complex drive mechanisms. The drive shaft is a straightforward rotational coupling that maintains system simplicity.
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 results in a compact and easily maintainable electrohydraulic actuator, where motor failures are simpler to address compared to pump failures, enhancing reliability and maintenance efficiency.
Implementation Method 1
an electric motor for selectively driving the pump in one direction or the other
Implementation Method 2
drives in rotation a shaft of non-circular section which extends in the cylinder passing through the piston
Implementation Method 3
The pump makes it possible to transfer fluid from one chamber to the other to move the piston
Data Source
Figure 1~3
AI summary
The invention relates to an electro-hydraulic actuator comprising a body (1) which defines a cylindrical cavity (2) in which a piston (3) sealingly slides and divides the internal volume of the cavity into two variable-volume chambers (A, B), the piston being associated with at least one rod (4) which passes sealingly through an end wall of the cavity, the actuator comprising a two-way pump (5) having two ports (Pl, P2) each connected to one of the chambers, an electric motor (8) for selectively driving the pump in one direction or the other, the pump being positioned in the piston of the actuator so that it can move therewith. According to the invention, the motor is placed at the end of an actuator and drives a shaft (6) of non-circular cross section extending into the cavity parallel to a direction of sliding of the piston (3) and of the rod (4), the shaft passing through the piston (3) in order to collaborate with a homologous drive member (11; 21) of the pump sliding freely along the shaft as the rod moves but rotationally driven as the shaft rotates under the action of the electric motor.