Mixer Drum Drive With Variable Displacement for Fuel-Efficient Speed Range
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Solution Overview
Problem
Conventional concrete mixer vehicles face inefficiencies in fuel 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 performance and reduced component life.
Innovation Solution
A drum drive system with a variable displacement pump and motor, controlled by a sophisticated control system, allows for a wide speed range and optimal operation by adjusting engine, pump, and motor displacements independently to maintain target drum speeds efficiently, reducing energy consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional hydrostatic drives with limited speed ratio ranges are used, then the drum can be driven at required speeds, but the engine must run at high or low idle, leading to poor fuel efficiency, increased noise, and reduced engine life
Solution Approach 1:
The patent applies dynamics by making the pump displacement variable rather than fixed. The pump displacement is continuously adjusted based on operating conditions to optimize fuel efficiency across different drum speeds. This dynamic adjustment allows the engine to operate at stable, fuel-efficient speeds while the variable pump displacement provides the necessary speed ratio range, resolving the contradiction between fuel efficiency and speed adaptability.
Solution Approach 2:
The patent changes the parameter of pump displacement from fixed to variable. By controlling pump displacement within a range, the system achieves a wide effective speed ratio range without requiring the engine to operate at inefficient high or low idle speeds. This parameter change enables the engine to maintain optimal operating conditions while still providing the required drum speed variability.
2Speed
If the engine runs at high or low idle to accommodate limited speed ratio ranges, then the drum speed can be maintained, but noise increases and engine life decreases
Solution Approach 1:
The system uses dynamic pump displacement control to maintain drum speed while keeping the engine operating within its optimal speed range. This eliminates the need for high or low idle operation, thereby reducing noise and extending engine life while maintaining the required drum speed performance.
Solution Approach 2:
The variable pump displacement acts as an intermediary between the engine and the drum drive system. It absorbs the speed ratio requirements, allowing the engine to operate steadily at optimal speeds rather than being forced into high or low idle conditions. This intermediary function protects the engine from harmful operating conditions while maintaining drum speed requirements.
3Device complexity
If fixed displacement pumps and motors are used, then the system structure is simpler, but the speed ratio range is limited and fuel consumption increases
Solution Approach 1:
The patent implements dynamics by making the pump displacement variable, which enables continuous optimization of fuel consumption across different operating conditions. Although this increases device complexity compared to fixed displacement systems, the fuel savings and performance improvements justify the added complexity of the variable displacement mechanism and its control system.
Solution Approach 2:
The patent changes the pump displacement parameter from fixed to variable, allowing the system to adapt to different drum speed requirements while maintaining optimal fuel efficiency. This parameter change enables the system to avoid the fuel consumption penalties associated with fixed displacement systems operating outside their optimal range.
4Use of energy by moving object
If variable displacement pump and motor are used with sophisticated control, then fuel efficiency and noise are improved, but the device complexity increases
Solution Approach 1:
The control system uses feedback from pressure sensors and operational data to continuously adjust pump displacement and optimize fuel efficiency. This feedback mechanism enables the system to maintain optimal performance while managing the complexity through intelligent control algorithms that adapt to changing operating conditions.
Solution Approach 2:
The control system operates autonomously, using sensor data and pre-programmed logic to adjust pump displacement without requiring constant operator intervention. This self-service capability manages system complexity by automating the control functions and reducing the operational burden on the user.
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 achieves improved fuel efficiency, reduced noise, extended engine life, and enhanced discharging accuracy by optimizing the speed and torque of the drum drive system, allowing the engine to operate at a stable, fuel-efficient speed without extreme displacement, thus improving overall performance.
Implementation Method 1
The pump has a variable pump displacement. The motor is fluidly coupled to the pump such that a motor speed of the motor is based on a flow of a fluid received from the pump
Implementation Method 2
The motor is fluidly coupled to the pump such that a motor speed of the motor is based on a flow of a fluid received from the pump
Data Source
AI summary
A drum drive system includes a controller configured to selectively control an engine, a variable displacement pump, and a variable displacement motor of a vehicle to provide a target drum speed for a drum of the vehicle. To provide the target drum speed, the controller is configured 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 an engine speed of the engine; (ii) increase the pump displacement and decrease a motor displacement without needing to actively manipulate the engine speed while still providing the target drum speed; and (iii) increase the engine speed in response to the pump displacement reaching a maximum pump displacement and the motor displacement reaching a minimum motor displacement if necessary to maintain the target drum speed.