Variable Displacement Hydraulic Drive for Flexible Wheel Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic drive systems for work vehicles, such as forklifts, are inflexible and require the electric motor to operate at specific revolutions per minute, limiting wheel movement and energy efficiency.
Innovation Solution
A drive system utilizing a variable displacement pump and an open-loop or closed-loop control unit to independently control the hydraulic pump and electric motor, allowing flexible operation and efficient energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a constant displacement pump is used with direct transmission to wheels, then the drive train is simple and reliable, but the electric motor must operate at fixed revolutions per minute and cannot serve additional consumers
Solution Approach 1:
The patent applies a variable displacement pump instead of a constant displacement pump, allowing the hydraulic flow to be dynamically adjusted based on the actual needs of the driven wheels and additional consumers. The pump's displacement can be varied to match different operating conditions, providing flexibility while maintaining system simplicity.
Solution Approach 2:
The invention changes the key parameter of pump displacement from fixed to variable. By controlling the pump's displacement parameter, the system can adapt to different operational requirements, enabling the electric motor to operate in favorable states while supporting multiple consumers simultaneously.
2Speed
If the electric motor is operated at high revolutions per minute to ensure wheel movement, then the driven wheels achieve desired speed, but the electric motor operates in an unfavorable and energy-consuming state
Solution Approach 1:
The variable displacement pump allows the system to decouple the electric motor's rotational speed from the wheel speed requirement. The pump can convert motor rotation at favorable speeds into the required hydraulic flow by adjusting displacement, enabling energy-efficient motor operation while maintaining desired wheel speeds.
Solution Approach 2:
The hydraulic pump acts as an intermediary between the electric motor and the driven wheels. It transforms the motor's mechanical energy into hydraulic energy, allowing the motor to operate in its optimal efficiency range while the hydraulic system delivers the required power to the wheels regardless of motor speed.
3Reliability
If the electric motor revolutions per minute are limited to protect the motor, then the driven wheels' movement is excessively limited
Solution Approach 1:
By varying the pump displacement, the system can achieve different wheel speeds from a single motor speed. When motor protection is needed, the pump displacement is reduced to maintain reliable motor operation while still providing adequate wheel movement through increased displacement ratio, thus protecting the motor without excessively limiting wheel movement.
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 system enables precise control of wheel movement and electric motor operation, enhancing flexibility and energy efficiency while supporting additional consumers.
Implementation Method 1
a hydraulic pump (11) which is designed to drive the at least one wheel (14), and an electric motor (10) mechanically coupled to the hydraulic pump (11), with the electric motor (10) being designed to drive the hydraulic pump (11)
Data Source
AI summary
A drive system for a work vehicle, for example a truck-mounted forklift, with at least one driven wheel, and the drive system includes a hydraulic pump designed to drive the driven wheel, and an electric motor mechanically coupled to the hydraulic pump. The electric motor is designed to drive the hydraulic pump, and the hydraulic pump is a variable displacement pump.