Hydraulic Control Device Pump Strategy for Fuel Efficiency
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Solution Overview
Problem
In hydraulic control devices with a first pump and a second pump connected in parallel, the second pump often operates wastefully when the request output exceeds its capability, leading to deteriorated fuel efficiency and pressure variations due to hunting of the check valve, especially during high-pressure oil supply or quick shift operations.
Innovation Solution
A hydraulic control device with a vehicle state grasping unit, output determination unit, and pump controller that stops or reduces the second pump's rotation if the request output exceeds its discharging capability, allowing the first pump to supplement oil supply through the check valve, thereby preventing wasteful operation and pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the second pump is continuously driven to meet high demand output, then the oil supply capability is improved, but the fuel efficiency deteriorates due to wasteful operation
Solution Approach 1:
The pump control device dynamically adjusts the operation mode between the first pump and second pump based on real-time oil demand. When demand exceeds the second pump's capability, the system switches to parallel operation mode, allowing the first pump to supplement oil supply, thereby avoiding continuous high-load operation of the second pump and improving fuel efficiency.
Solution Approach 2:
The hydraulic control system is designed with dual pump capability where the first pump (mechanical pump driven by engine) and second pump (electric pump) can both supply oil to the hydraulic operation unit. This multi-functionality allows flexible allocation of pumping tasks based on demand, enabling the system to meet high oil supply requirements without overloading the second pump.
2Productivity
If both the first pump and second pump are operated together to meet high demand, then the oil supply capability is improved, but the check valve hunting occurs causing pressure variation
Solution Approach 1:
The pump control device incorporates a feedback mechanism that monitors the operation state of the first and second pumps. When both pumps are operating and the check valve is in an unstable state, the control device adjusts the second pump's operation to prevent hunting, thereby stabilizing the pressure in the common oil gallery while maintaining adequate oil supply capability.
3Speed
If the second pump operates at full capacity to meet quick shift operation demand, then the response speed is improved, but the fuel efficiency deteriorates
Solution Approach 1:
The system maintains the first pump (mechanical pump driven by engine) as a ready source of oil supply that can be immediately activated when quick shift operation is detected. This preliminary arrangement eliminates the need to continuously operate the second pump at high capacity, providing fast response when needed while avoiding unnecessary energy consumption during normal operation.
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 enhances fuel efficiency by avoiding wasteful operation of the second pump and stabilizes oil pressure supply to the hydraulic operation unit, ensuring appropriate oil delivery based on vehicle state demands.
Implementation Method 1
a check valve connected in parallel and configured to supply first oil from the first pump to the hydraulic operation unit through the check valve
Implementation Method 2
pressurize the first oil that is supplied from the first pump with the second pump and supply the first oil that has been pressurized to the hydraulic operation unit as second oil
Data Source
AI summary
In a control unit of a hydraulic control device, a vehicle state grasping unit grasps a vehicle state of a vehicle, and an output determination unit determines whether an operation point depending on the vehicle state that is decided by an operation point decision unit is over a discharging capability limit line. A pump controller stops a second pump or decreases a rotation number if the output determination unit determines that the operation point is over the discharging capability limit line.