Hydrostatic Driveline with Variable Displacement and Accumulator
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Solution Overview
Problem
Conventional hydrostatic drivelines are inefficient, restricted to a narrow speed range, and include expensive, specialized components, leading to high fuel consumption, increased costs, and reduced productivity for vehicles.
Innovation Solution
A hydrostatic driveline system utilizing variable displacement motors and pumps, along with a controller that optimizes fluid displacement and output pressure, and an accumulator state of charge control system to minimize fuel consumption and enable operation over a wide range of speeds using easily procurable and serviced components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an internal combustion engine is oversized to accommodate peak power demand in a conventional hydrostatic driveline, then the vehicle can meet maximum power requirements, but fuel consumption increases and efficiency decreases during normal operation
Solution Approach 1:
The patent applies dynamics by making the pump displacement variable rather than fixed. The variable displacement pump adjusts its fluid displacement based on actual operating conditions, allowing the system to match power output to demand in real-time. This resolves the contradiction by enabling the pump to operate efficiently at partial load while still providing peak power when needed, rather than being constantly oversized.
Solution Approach 2:
The patent changes the parameter of pump displacement from fixed to variable. By adjusting the displacement parameter based on operating conditions, the system can optimize fuel consumption across different power demands while maintaining the capability to deliver peak power when required.
2Device complexity
If a conventional hydrostatic driveline uses fixed displacement pumps and motors, then the system structure is simple, but the vehicle is restricted to a narrow speed range
Solution Approach 1:
The patent applies dynamics by implementing variable displacement capability in both the pump and motor. This allows the system to continuously adjust fluid displacement to maintain optimal operation across a wide speed range, transforming the fixed-speed limitation into a variable-speed capability while keeping the overall system structure relatively simple.
3Force
If specialized components like large hydraulic pumps, motors, and valving systems are used in a conventional hydrostatic driveline, then high torque output is achieved, but the initial cost and service cost greatly increase
Solution Approach 1:
The patent changes the operational parameters of standard components through variable displacement control, enabling them to deliver high torque output when needed without requiring oversized fixed displacement components. This approach allows the use of more commonly available, cost-effective components while maintaining the ability to generate high torque on demand.
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 enhances vehicle efficiency, reduces noise, allows for discontinuous energy release, and provides precision control, thereby reducing costs and improving productivity by optimizing power usage and component accessibility.
Implementation Method 1
a hydrostatic driveline for a vehicle including a power source, a pump drivingly engaged with the power source, a motor, and the hydrostatic accumulator
Data Source
AI summary
A method for minimizing a fuel consumption rate of a vehicle and a method for tracking an optimal state of charge function for a hydrostatic accumulator are provided. The first method includes the steps of providing a motor and pump, determining an efficiency of the motor and pump using an efficiency map, providing a power source, and controlling the motor independent from the pump with a controller. The controller employs the efficiency of the motor and the pump to minimize the fuel consumption rate of the vehicle. The second method includes the steps of determining the optimal state of charge control function, calculating an optimal state of charge of the hydrostatic accumulator, determining a state of charge error, calculating a corrective value, and adjusting a state of a charge based on the corrective value and the state of charge error by adjusting the charge of the hydrostatic accumulator.