Hydraulic Control Device for Drive Power Distribution
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Solution Overview
Problem
The hydraulic pressure sealing-type hydraulic control device in four-wheel-drive vehicles generates operation noise when the solenoid valve is closed, which can be misinterpreted as a malfunction by the driver and passengers, especially during low-speed operations or acceleration.
Innovation Solution
A drive power distribution device with a hydraulic clutch, oil pump, hydraulic fluid sealing valve, on-off valve, control means, hydraulic pressure detection, and vehicle speed detection, which synchronizes the closure of the on-off valve with vehicle speed and hydraulic pressure to minimize noise recognition, using a normally open-type electromagnetic valve and adjusting oil pressure based on calculated drive power and vehicle conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the solenoid valve is closed to maintain hydraulic pressure sealing, then the four-wheel-drive state can be maintained without continuous pump operation, but operation noise is generated when the valve closes
Solution Approach 1:
The control device closes the on-off valve before the accelerator control timing to prevent synchronous noise. By performing the valve closure action in advance (when vehicle speed is low and hydraulic pressure is stable), the noise occurrence is decoupled from the driver's accelerator operation, making the noise less recognizable and preventing misinterpretation as malfunction.
2Productivity
If the on-off valve is closed at the same timing as accelerator control, then four-wheel-drive engagement is synchronized with acceleration, but noise becomes easily recognizable and may be misinterpreted as malfunction
Solution Approach 1:
The control device applies preliminary anti-action by closing the on-off valve before the accelerator control timing. This preemptive timing adjustment prevents the harmful effect (noise synchronizing with acceleration) from occurring, thereby eliminating the misinterpretation risk while maintaining engagement responsiveness.
3Reliability
If the on-off valve is closed at low vehicle speed, then hydraulic pressure can be established, but the operation noise is more easily heard by driver and passenger
Solution Approach 1:
The control device performs the valve closure action in advance when vehicle speed is low and hydraulic pressure is stable, rather than waiting for higher speeds where noise would be masked by road noise. This preliminary timing ensures reliable pressure establishment while the noise occurs during conditions (low speed, stable pressure) that allow for better acoustic masking through subsequent operational noise.
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 effectively reduces the recognizability of operation noise from the on-off valve closure, preventing misinterpretation of malfunctions and improving drive power distribution responsiveness by controlling the solenoid valve closure based on hydraulic pressure and vehicle speed thresholds.
Implementation Method 1
an oil pump (35) for supplying hydraulic fluid to a piston chamber (15) of the hydraulic clutch (10)
Implementation Method 2
a solenoid valve (on-off valve) This hydraulic control device is configured to drive the electric oil pump and simultaneously close the solenoid valve
Data Source
AI summary
A drive power distribution device includes a hydraulic pressure sealing-type hydraulic pressure control device for making an operation noise of an on-off valve such as a solenoid valve less recognizable to occupants of a vehicle. By closing the on-off valve and driving the oil pump, a hydraulic pressure detected using a hydraulic pressure detection means reaches a target hydraulic pressure, and fastening power of a hydraulic clutch is maintained at an oil pressure of hydraulic fluid sealed in an oil passage until the on-off valve is opened. The drive power distribution device closes the solenoid valve when the hydraulic pressure is detected to be equal to or less than a predetermined threshold hydraulic pressure and equal to or less than a predetermined threshold vehicle speed. This can prevent synchronization between an accelerator operation by a driver and a closing operation of the solenoid valve.