Hydrostatic Drive Controller for Smooth Speed Transitions
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Solution Overview
Problem
Conventional hydrostatic drive systems experience sudden acceleration and deceleration shocks during gear shifting, leading to reduced efficiency in machines like skid steer loaders, due to the lack of controlled displacement adjustments in hydraulic motors and pumps.
Innovation Solution
A hydrostatic drive system with a controller that receives input signals for current and desired machine speeds, adjusting the displacement of both the hydraulic motor and pump to maintain constant speed, acceleration, or deceleration, thereby smoothing the shifting process by outputting motor and pump displacement command signals to adjust the swash plate angles of the hydraulic motor and pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional hydrostatic drive systems perform gear shifting, then speed changes are achieved, but sudden acceleration and deceleration shocks occur
Solution Approach 1:
The controller adjusts the displacement of the hydraulic motor and pump in a coordinated sequence before and during the shifting process. The motor displacement is adjusted first to prepare for speed change, followed by pump displacement adjustment, ensuring smooth transition without sudden shocks to the machine.
Solution Approach 2:
The system dynamically adjusts the displacement of both the hydraulic motor and pump during operation based on current and desired speed signals. This dynamic coordination allows the system to maintain smooth speed transitions by continuously adapting the displacement parameters rather than making abrupt changes.
2Ease of operation
If the displacement of hydraulic motor is adjusted during shifting, then speed control is improved, but sudden changes cause reduced efficiency
Solution Approach 1:
The controller receives feedback signals about the current machine speed and compares it with the desired speed. Based on this feedback, the controller continuously adjusts the motor and pump displacement to maintain optimal speed control while avoiding sudden changes that would reduce machine efficiency.
Solution Approach 2:
The system changes the displacement parameters of the hydraulic motor and pump in a controlled manner during shifting. By gradually adjusting these parameters rather than making abrupt changes, the system achieves smooth speed control while maintaining high machine efficiency throughout the transition.
Data Source
AI summary
A hydrostatic drive system for a machine is disclosed. The hydrostatic drive system includes a pump, a hydraulic motor configured to receive a pressurized fluid from the pump and a controller operably connected to the pump and the hydraulic motor. The controller is configured to receive an input signal indicative of a current machine speed and a desired machine speed. Further, the controller is configured to output a motor displacement command signal and a pump displacement command signal to adjust a displacement of the hydraulic motor and the pump respectively based on the input signal to maintain at least one of constant machine speed or constant acceleration or constant deceleration during adjustment of the pump displacement and the motor displacement.