Torque-Sensing Variable Displacement Hydraulic Pump
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Solution Overview
Problem
Existing variable displacement hydraulic pumps face challenges in quickly and accurately attaining or maintaining a desired flow rate due to errors and lag induced by downstream measurements of pressure or flow, which are affected by overall hydraulic system pressures.
Innovation Solution
A variable displacement hydraulic pump with torque sensing, featuring a torque sensor to measure torque on the drive shaft and transmit signals to a processor, which generates control signals for an actuator to pivot or maintain the position of the swash plate or cylinder block, allowing for precise control of fluid flow rates based on torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downstream pressure or flow measurements are used for control feedback, then the control system can be implemented with existing sensors, but the control accuracy and response speed are degraded due to errors and lag
Solution Approach 1:
Instead of measuring flow rate downstream to control the pump, the invention inverts the approach by measuring torque at the drive shaft and using it to determine flow rate. This upstream measurement of a related parameter (torque correlates to flow rate) eliminates the lag and errors associated with downstream flow measurements, achieving both high accuracy and fast response.
2Measurement precision
If downstream pressure measurements are used for control feedback, then the control system can be implemented, but the control precision is degraded due to the effect of overall hydraulic system pressure
Solution Approach 1:
The invention extracts the flow rate information from a different measurement point (torque at drive shaft) rather than relying on downstream pressure or flow measurements that are contaminated by system pressure effects. By measuring torque at the drive shaft where it is not affected by downstream hydraulic conditions, the harmful factor of system pressure interference is eliminated.
3Measurement precision
If an electromechanical actuator is used to control the piston, then the control precision is improved, but the control loop still contains errors and lag due to downstream measurement
Solution Approach 1:
The invention implements a new feedback mechanism by measuring torque at the drive shaft and using it to determine flow rate for control purposes. This torque-based feedback provides real-time, accurate information about the pump's actual flow output, enabling the control system to quickly adjust the swash plate position to maintain desired flow rate without the lag and errors of downstream measurements.
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 quick and accurate adjustment or maintenance of flow rates, reducing errors and lag by providing in-stream torque feedback, thus improving the pump's ability to correlate flow rates with torque levels and maintain desired flow rates despite changes in system conditions.
Implementation Method 1
a torque sensor arranged to measure torque on the drive shaft; and transmit a torque signal, including the measured torque, to a processor
Implementation Method 2
a swash plate engaged with the first and second pistons and arranged to displace the first and second pistons within the first and second through-bores, respectively, to draw fluid through the inlet port into the first and second through-bores; and expel the fluid from the first and second through-bores into the outlet port
Data Source
AI summary
A pump, including: a cylinder block including two through-bores and two pistons disposed in the through-bores; a drive shaft to rotate the cylinder block; a swash plate to displace the pistons within the through-bores to draw fluid through an inlet port into the through-bores; and expel the fluid from the through-bores into the outlet port; a torque sensor arranged to measure torque on the drive shaft and transmit a torque signal, including the measured torque, to a processor; and an actuator to receive, from the processor, a control signal generated using the torque signal and pivot the swash plate about a first axis, transverse to the axis of rotation, or maintain a circumferential position of the swash plate about the first axis; or pivot the cylinder block about a second axis, transverse to the axis of rotation, or maintain a circumferential position of the cylinder block about the second axis.