Variable Displacement Drum Drive for Wide-Range Speed Control
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Solution Overview
Problem
Conventional concrete mixer vehicles face inefficiencies in energy consumption, noise, emissions, and accuracy in discharging due to limited speed ratio ranges of hydrostatic drives, which require engines to run at high or low idle, leading to poor fuel efficiency and reduced engine life.
Innovation Solution
The implementation of a drum drive system with a variable displacement motor and pump, allowing for a wider speed range and independent control of engine, pump, and motor displacements to optimize drum speed and torque, reducing engine speed extremes and enhancing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional hydrostatic drives with fixed displacement components are used, then the system structure is simple, but the engine must run at high or low idle leading to poor fuel efficiency and high emissions
Solution Approach 1:
The patent applies dynamics by replacing fixed displacement components with variable displacement components. The variable displacement pump and variable displacement motor allow the system to dynamically adjust flow and torque based on actual operating conditions, enabling the engine to operate at optimal speeds rather than fixed idle speeds, thereby improving fuel efficiency and reducing emissions.
Solution Approach 2:
The patent changes the parameters of the hydraulic components from fixed to variable. By enabling continuous adjustment of displacement parameters in both the pump and motor, the system can optimize engine operating parameters (speed and load) to match actual demand, eliminating the need for high or low idle operation and significantly improving fuel efficiency.
2Speed
If variable displacement components are implemented to widen speed range, then fuel efficiency improves, but system complexity increases
Solution Approach 1:
The patent implements dynamics through variable displacement components that continuously adjust their operating characteristics. The variable displacement pump and motor enable the system to achieve a wide speed range by dynamically changing displacement parameters, allowing precise control over drum speed while maintaining engine operation within efficient parameters.
Solution Approach 2:
The variable displacement components serve multiple functions: they act as speed controllers, torque regulators, and engine load managers simultaneously. This multi-functionality allows the system to achieve wide speed range capability without proportionally increasing complexity, as the same components perform multiple control tasks.
3Object-generated harmful factors
If engine speed is reduced to improve fuel efficiency, then emissions decrease, but drum speed control accuracy may be compromised
Solution Approach 1:
The patent changes the operational parameters from engine-speed-dependent to displacement-dependent control. By varying the displacement parameters of the pump and motor independently of engine speed, the system can maintain precise drum speed control while operating the engine at lower, more efficient speeds, thereby reducing emissions without sacrificing control accuracy.
Solution Approach 2:
The patent replaces direct mechanical coupling between engine speed and drum speed with a hydraulic mediation system. The variable displacement pump and motor create a decoupled relationship, allowing drum speed to be precisely controlled through displacement adjustments rather than direct engine speed linkage, enabling accurate control at reduced engine speeds and lower emissions.
4Loss of energy
If fixed displacement pump and motor are used, then system reliability is high, but energy consumption increases due to limited speed ratio control
Solution Approach 1:
The patent transforms the system from fixed parameter operation to variable parameter operation. By enabling continuous adjustment of displacement parameters in the pump and motor, the system can optimize energy consumption across different operating conditions while maintaining reliable operation through controlled parameter variation within design specifications.
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
This solution provides improved fuel efficiency, reduced emissions, and increased accuracy in concrete discharging by allowing the engine to operate at optimal speeds, while maintaining stable torque and minimizing energy consumption.
Implementation Method 1
a variable displacement pump mechanically coupled to the engine
Implementation Method 2
a variable displacement motor fluidly coupled to the variable displacement pump
Data Source
AI summary
A drum drive system includes a controller configured to control a prime mover, a variable displacement pump, and a variable displacement motor of the vehicle to provide a target drum speed for a drum of the vehicle. To provide the target drum speed, the controller having programmed instructions to (i) initially operate the variable displacement motor at a maximum motor displacement and operate the variable displacement pump at a pump displacement that provides the target drum speed without needing to actively manipulate a prime mover speed of the prime mover, (ii) increase the pump displacement and decrease a motor displacement without needing to actively manipulate the prime mover speed while still providing the target drum speed, and (iii) increase the prime mover speed if necessary to maintain the target drum speed in response to the pump displacement reaching a maximum pump displacement and the motor displacement reaching a minimum motor displacement.