Variable-Displacement Hydraulic Drive for Flexible Work Vehicle Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic drive systems in compact electric work vehicles, such as forklifts and excavators, are inflexible and inefficient due to the use of constant-displacement pumps, which require the electric motor to operate at a specific speed for wheel movement, limiting flexibility and energy efficiency.
Innovation Solution
Implementing a variable displacement pump and a control unit to regulate both the hydraulic pump and electric motor, allowing independent control of wheel movement and motor operation, enabling flexible and energy-efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a constant-displacement pump is used in the hydraulic drive system, then the structure is simpler, but the system cannot operate additional electrical components and the electric motor must operate at a fixed speed corresponding to desired wheel movement, reducing flexibility
Solution Approach 1:
The patent applies the dynamics principle by replacing the constant-displacement pump with a variable-displacement pump that can dynamically adjust its displacement according to system needs. This allows the hydraulic drive system to adapt to different operating conditions, enabling flexible control of wheel movement speed and the operation of additional electrical components without disrupting power transmission.
2Speed
If the electric motor speed is strictly coupled to wheel movement requirements, then direct power transmission is maintained, but the motor cannot operate in optimal conditions and maximum motor speed excessively limits wheel movement
Solution Approach 1:
The variable-displacement pump acts as an intermediary between the electric motor and the wheels. It decouples the direct speed relationship, allowing the motor to operate at optimal speeds while the pump adjusts hydraulic fluid delivery to achieve desired wheel movement speeds. This intermediary enables the motor to run in energy-efficient operating ranges while still providing the required wheel speed range.
3Adaptability or versatility
If additional electrical components are operated in the system, then functionality is enhanced, but the direct power transmission from pump to wheels is disrupted
Solution Approach 1:
The variable-displacement pump dynamically adjusts its operation based on system demands. When additional electrical components are activated, the pump can reduce its displacement to accommodate the extra power demand while maintaining reliable power transmission to the wheels. This dynamic adjustment ensures both enhanced functionality and maintained transmission reliability.
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 drive system achieves enhanced flexibility and energy efficiency by allowing gentle motor operation and precise control of wheel movement, supporting additional consumers and maintaining optimal motor conditions.
Implementation Method 1
a hydraulic pump (11) which is designed to drive at least one wheel (14) of the work vehicle
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Drive system (1) for a work vehicle, for example a truck-mounted forklift, with at least one driven wheel (14), wherein the drive system (1) comprises a hydraulic pump (11) designed to drive the at least one driven wheel (14), and an electric motor (10) mechanically coupled to the hydraulic pump (11) designed to drive the hydraulic pump (11), wherein the hydraulic pump (11) is a variable displacement pump.