Hydrostatic Transmission Swash Plate Control for Smooth Gear Shifting
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Solution Overview
Problem
Hydrostatic transmissions in work vehicles experience gear shifting shocks and engine stalls, particularly in agricultural applications, disrupting constant-speed driving and reducing output to attached implements.
Innovation Solution
A hydrostatic transmission system with a controller that adjusts the angular position of swash plates in the hydraulic motor and pump based on engine load states, using servo-mechanisms to minimize gear shifting shocks and prevent engine stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single servo-mechanism controls the swash plate in the hydraulic pump, then the device complexity is reduced, but gear shifting shocks and engine stalls occur disrupting constant-speed driving
Solution Approach 1:
The control system is divided into two independent servo-mechanisms: one controlling the swash plate in the hydraulic pump and another controlling the swash plate in the hydraulic motor. This segmentation allows independent optimization of each control stage, enabling precise management of flow rate changes and rotational speed variations to prevent gear shifting shocks and engine stalls while maintaining constant-speed driving.
2Device complexity
If the swash plate angular position is fixed, then the device complexity is reduced, but the adaptability to different load states and working conditions is limited
Solution Approach 1:
The swash plates in both the hydraulic pump and hydraulic motor are equipped with servo-mechanisms that dynamically adjust their angular positions based on real-time operating conditions. This dynamic adjustment capability allows the system to adapt to varying load states, maintain optimal performance across different working conditions, and prevent gear shifting shocks and engine stalls by continuously optimizing the flow rate and rotational speed.
3Productivity
If gear shifting is achieved through swash plate rotation, then the productivity and working efficiency are improved, but gear shifting shocks occur that disrupt constant-speed driving
Solution Approach 1:
The dual servo-mechanism control system preemptively manages the angular position changes of both swash plates during gear shifting operations. By coordinating the adjustment of the pump swash plate (controlling flow rate) and the motor swash plate (controlling rotational speed), the system cushions the impact of gear shifting before it occurs, eliminating shocks that would otherwise disrupt constant-speed driving and reduce working efficiency.
4Adaptability or versatility
If the hydraulic pump provides variable flow rate to the hydraulic motor, then the adaptability to different speed requirements is improved, but engine stalls occur due to sudden load changes
Solution Approach 1:
The servo-mechanism controlling the hydraulic motor's swash plate receives feedback regarding engine load state and rotational speed. This feedback mechanism allows the system to detect sudden load changes and adjust the motor's flow rate and speed accordingly, preventing engine stalls while maintaining the ability to vary speed according to different working conditions. The coordinated control of both pump and motor swash plates ensures smooth transitions that protect engine operation stability.
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 ensures stable, constant-speed driving and enhanced work performance by minimizing gear shifting shocks and engine stalls, improving ride comfort and work efficiency.
Implementation Method 1
a hydraulic motor configured to generate the rotational force of an output shaft by hydraulic pressure
Implementation Method 2
a hydraulic pump configured to provide hydraulic pressure to the hydraulic motor, and to vary flow rate, provided to the hydraulic motor
Data Source
AI summary
The present disclosure is directed to a hydrostatic transmission for a work vehicle and a method of controlling the same. The hydrostatic transmission for a work vehicle according to the present disclosure is rotatably provided with a swash plate in a hydraulic motor, and the angle of the swash plate is adjusted by a servo-mechanism in response to a current load state. According to the present disclosure, gear shift shocks and engine stalls may be minimized.