Hydraulic Control Device for Drive Power Distribution
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Solution Overview
Problem
Conventional hydraulic control devices for four-wheel-drive vehicles face challenges in providing highly accurate control, especially in low-torque regions, due to limitations in motor durability and potential overshoot issues during transitions in hydraulic pressure control.
Innovation Solution
A hydraulic control device with a sealed-type hydraulic circuit, including an oil pump, hydraulic fluid sealing valve, on-off valve, and accumulator, which employs distinct control characteristics for pressurizing, maintaining, and depressurizing the piston chamber, allowing for fine hydraulic control and reduced motor usage, thereby improving durability and accuracy in low-torque regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric oil pump is always operated to supply hydraulic pressure to the hydraulic clutch, then the hydraulic clutch engagement pressure is maintained, but the motor durability deteriorates due to continuous operation and brush wear
Solution Approach 1:
The patent implements periodic action by controlling the electric oil pump to operate only during specific phases (pressurization phase) rather than continuously. The pump is activated when hydraulic pressure needs to be increased or maintained, and deactivated when pressure is sufficient or during depressurization phase, thereby reducing continuous operation time and extending motor durability while ensuring hydraulic clutch engagement pressure is maintained when needed
2Duration of action of stationary object
If the hydraulic pressure sealed-type control device uses stepwise motor drive to pressurize the piston chamber, then motor usage is reduced improving durability, but control accuracy deteriorates in low-torque regions
Solution Approach 1:
The patent applies dynamics by implementing three distinct hydraulic pressure control characteristics (first, second, and third characteristics) that dynamically adapt to different operating conditions. The control device selects among these characteristics based on the current torque region and operational phase, enabling accurate control in low-torque regions through the third characteristic while maintaining motor durability benefits through stepwise drive in the first characteristic for pressurization
Solution Approach 2:
The patent utilizes parameter changes by switching between different control characteristics that modify hydraulic pressure supply parameters. The third characteristic enables fine hydraulic control with continuous pressure adjustment for high accuracy in low-torque regions, while the first characteristic uses stepwise pressure increases for durable motor operation during pressurization, achieving both goals through parameter adaptation
3Stress or pressure
If the on-off valve is closed and the oil pump is driven to pressurize the piston chamber, then hydraulic pressure is increased, but overshoot may occur during transition from low-torque to high-torque region
Solution Approach 1:
The patent implements preliminary anti-action by detecting when the system is transitioning from low-torque to high-torque region and preemptively limiting motor drive before overshoot can occur. The controller monitors the torque region transition and applies drive limitation control in advance during the pressurization phase, preventing the hydraulic pressure from exceeding the target value while still achieving the necessary pressure increase through coordinated valve and pump control
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 solution enables highly accurate four-wheel-drive control in low-torque regions by reducing motor usage and preventing overshoot, enhancing the durability of the motor and maintaining constant clutch engagement force, while ensuring precise hydraulic pressure management.
Implementation Method 1
an oil pump which is driven with a motor and supplies hydraulic fluid to the piston chamber
Implementation Method 2
a hydraulic fluid sealing valve configured to seal the hydraulic fluid to a fluid path allowing communication between the oil pump and the piston chamber
Implementation Method 3
an accumulator configured to reserve the hydraulic pressure for the piston chamber
Data Source
AI summary
A device is provided which performs highly-accurate control in low-torque regions while taking advantage of hydraulic pressure sealed-type hydraulic control devices. The device includes: a first characteristic (sealed pressurization) obtained by closing the on/off valve and driving an oil pump: a second characteristic (sealed depressurization) obtained by disabling drive of the oil pump and opening the on/off valve; and a third characteristic (flow-rate control) obtained by opening the on/off valve and driving the oil pump. In the process of supplying hydraulic pressure to a piston chamber in a low torque region, the device performs control according to the third characteristic. In the process of pressurizing the piston chamber in a torque region higher than the low torque region, the device performs control according to the first characteristic. In the subsequent process of depressurizing the piston chamber, the device performs control according to the second characteristic.