Sensorless Hydraulic Pump Control With Variable Motor Speed
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Solution Overview
Problem
Hydraulic pump systems in working vehicles are inefficient due to energy losses in pipes and unnecessary operation when hydraulic fluid demand is low, leading to reduced efficiency and cumbersome maintenance.
Innovation Solution
A hydraulic system with electric motors controlling variable hydraulic fluid output through speed adjustment, eliminating the need for rotor positioning sensors and using fixed displacement pumps, coupled with motor controllers that calculate command signals based on user inputs and operational parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotor positioning sensor is used in the electric motor, then the control precision and dynamic response are improved, but the device complexity and cost increase
Solution Approach 1:
The patent removes the rotor positioning sensor from the electric motor system, extracting the sensing function entirely. The motor controller operates without feedback from rotor position sensors, using open-loop control based on command signals alone. This eliminates the complexity and cost associated with sensor installation while maintaining sufficient control performance for hydraulic pump operation.
Solution Approach 2:
The electric motor system serves itself by operating without external position sensing. The motor controller generates control signals based on command inputs and internally manages motor operation through sensorless control algorithms, allowing the system to function autonomously without additional sensing components.
2Reliability
If the hydraulic pump operates continuously when the ICE is running, then the hydraulic fluid supply is ensured, but the energy loss increases due to unnecessary operation
Solution Approach 1:
The electric motor's rotation speed is dynamically adjusted based on the actual hydraulic fluid demand. The motor controller varies the speed command signal according to operational requirements, allowing the pump to operate only when needed and at the appropriate speed, thereby eliminating energy waste from continuous operation while ensuring reliable fluid supply when required.
Solution Approach 2:
The system changes the operational parameters of the electric motor by adjusting rotation speed rather than maintaining constant operation. The motor controller modifies speed parameters dynamically, enabling the pump to match hydraulic demand and avoid energy loss from unnecessary full-speed operation.
3Loss of energy
If the hydraulic pump output is reduced by altering swash angle, then the energy loss is reduced, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical variable swash plate mechanism with an electric motor-driven fixed displacement pump. Instead of mechanically altering the pump's internal geometry to vary output, the system uses electrical speed control of the motor to adjust hydraulic fluid delivery, eliminating the complex mechanical adjustment mechanism while achieving the same energy efficiency goal.
Solution Approach 2:
The system achieves variable hydraulic output by changing the motor speed parameter rather than altering the pump's mechanical displacement characteristics. This parameter-based control approach simplifies the pump mechanism while maintaining the ability to match hydraulic supply with demand.
4Ease of operation
If long pipes are used to supply hydraulic fluid, then the pump can be positioned remotely, but the energy loss along the pipe length increases
Solution Approach 1:
The patent extracts and eliminates the long hydraulic piping from the system by positioning the electric motor-driven pump directly at the hydraulic system. This removes the source of pipe-related energy losses while maintaining pump positioning flexibility through the electrical control architecture.
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
Improves efficiency and responsiveness of hydraulic systems by optimizing hydraulic fluid output and reducing energy losses, while simplifying maintenance and operation without the need for rotor positioning sensors.
Implementation Method 1
an electric motor coupled to the hydraulic pump assembly such that output of hydraulic fluid from the hydraulic pump assembly is varied by adjusting the rotation speed of the electric motor
Implementation Method 2
a hydraulic pump assembly for supplying a variable output of hydraulic fluid to the hydraulically actuated device
Data Source
AI summary
A working machine including a hydraulic system. The hydraulic system includes: a hydraulically actuated device; a hydraulic pump assembly for supplying a variable output of hydraulic fluid to the hydraulically actuated device; an electric motor coupled to the hydraulic pump assembly such that output of hydraulic fluid from the hydraulic pump assembly is varied by adjusting the rotation speed of the electric motor; and a motor controller configured to: generate a motor control signal for operating the electric motor based on a motor speed command signal. The hydraulic system does not include a rotor positioning sensor arranged to sense the rotational position of a rotor of the electric motor.