Hydraulic Actuator Rocking Torque Control
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Solution Overview
Problem
Oil hydraulic actuators face challenges in achieving high power-to-weight ratios and controllability, especially under low-velocity and high-torque conditions, due to energy consumption issues with pressurization and accumulator systems, leading to larger sizes and heat generation problems.
Innovation Solution
A rotatable hydraulic actuator design featuring a swash member, universal joint mechanism, high-pressure and low-pressure pipe portions, a pump mechanism, rocking-torque generation mechanisms, and a control valve device that allows for efficient energy transfer and reduced energy consumption by controlling rocking torque and adjusting the relative angle between rotational members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a throttle is employed for adjusting the velocity in cylinder-type or vane-type oil hydraulic actuators, then velocity control is achieved, but energy is vainly consumed within the accumulator as losses during operations at lower velocity
Solution Approach 1:
The patent extracts the throttle component from the hydraulic actuator system, replacing it with a direct connection between the accumulator and the actuator. This eliminates the energy loss associated with throttle-based velocity control while maintaining the ability to control velocity through other means (such as controlling the rate of oil flow from the accumulator).
Solution Approach 2:
The patent introduces a control valve as an intermediary component between the accumulator and the hydraulic actuator. This control valve regulates the flow of oil from the accumulator to the actuator, enabling velocity control without the energy losses associated with traditional throttle mechanisms. The control valve mediates between the high-pressure accumulator and the actuator to achieve efficient velocity regulation.
2Power
If an oil hydraulic pump and accumulator are used to provide high power-to-weight ratio, then power density is improved, but the system requires larger sizes and cooling mechanisms due to heat generation from losses
Solution Approach 1:
The patent removes the throttle component that causes energy loss and heat generation. By eliminating this source of inefficiency, the system maintains high power-to-weight ratio while significantly reducing heat generation from energy losses.
Solution Approach 2:
The patent converts the high-pressure energy stored in the accumulator from a potential source of energy loss into useful work. By directly connecting the accumulator to the actuator through a control valve, the system utilizes the stored energy efficiently, converting what would have been waste heat into productive mechanical work.
3Use of energy by moving object
If variable-displacement axial piston-type oil hydraulic actuators are used to operate at constant pressure, then energy consumption by accumulator is facilitated, but a large force is required for changing the angle of the swash plate, reducing controllability
Solution Approach 1:
The patent extracts the swash plate mechanism from the actuator design, replacing it with a simpler piston-cylinder arrangement. This eliminates the need for large forces to change the swash plate angle, thereby improving controllability while maintaining efficient energy consumption from the accumulator.
Solution Approach 2:
Instead of using a variable-displacement mechanism (swash plate) to control output, the patent inverts the approach by using a fixed-displacement actuator with a control valve to regulate flow from the accumulator. This inversion simplifies the mechanical structure and improves controllability while achieving the same energy efficiency goals.
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 design enhances controllability and reduces the weight of the pressurization unit, prevents energy wastage in the accumulator, and improves the power-to-weight ratio, enabling efficient operation and reduced sizes of the pump and accumulator mechanisms.
Implementation Method 1
a pump mechanism which transfers the non-compressible fluid in the low-pressure pipe portion to the high-pressure pipe portion
Implementation Method 2
a control valve device which controls connection of the non-compressible fluid between the rocking-torque generation mechanisms and the high-pressure pipe portion as well as the low-pressure pipe portion
Implementation Method 3
rocking-torque generation mechanisms which are driven by the non-compressible fluid to generate a rocking torque to the swash member
Data Source
AI summary
There are provided a swash member and a first and second rotational members which are held on a base member through a universal joint mechanism and can rock about two axes out of three orthogonal axes including a center of the mechanism, a pump mechanism for transferring a low-pressure non-compressible fluid in a low-pressure pipe portion to a high-pressure pipe portion filled with a high-pressure non-compressible fluid being pressurized by a pressure accumulation mechanism, a control valve device which controls connection between both the pipe portions and a plurality of rocking-torque generation mechanisms which couple the base member and the swash member to each other and are driven by the fluids for generating a rocking torque to the swash member, and rocking-angle adjustment unit for changing a relative angle between the two rotational members.