Cooling Fan Control Device for Hydraulic Pressure Management
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Solution Overview
Problem
The existing cooling fan control devices may cause excessive pressure in the hydraulic circuit when switching the rotation direction of the cooling fan, leading to reduced durability of components due to potential malfunctions or inadequate decay of the hydraulic motor's rotation speed.
Innovation Solution
A cooling fan control device with a control unit that adjusts the relief pressure setting at a variable relief valve to lower the discharge pressure before switching the direction of the hydraulic motor, ensuring a smooth transition from forward to reverse rotation and vice versa, using predetermined pressure settings and time intervals to manage the pressure within the hydraulic circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the cooling fan control device outputs a control signal to switch the rotation direction after a predetermined time elapses, then the rotation direction can be switched automatically, but the pressure in the hydraulic circuit may increase sharply causing excessive load on components
Solution Approach 1:
The control unit continuously monitors the discharge pressure via the pressure sensor and uses this feedback to determine the optimal timing for direction switching. The system waits until the discharge pressure drops to or below the switch-over pressure before activating the direction switching valve, ensuring that switching occurs only when hydraulic pressure is sufficiently low to prevent component damage.
Solution Approach 2:
The system performs preliminary pressure reduction by allowing the discharge pressure to drop to the switch-over pressure before executing the direction switching operation. This preliminary action ensures that the hydraulic circuit is in a safe pressure state prior to the mechanical switching event, preventing excessive load on components.
2Loss of time
If the discharge pressure is not sufficiently lowered before switching rotation direction, then the switching operation can be performed quickly, but excessive load is placed on hydraulic circuit components
Solution Approach 1:
The control unit uses real-time pressure feedback from the pressure sensor to dynamically determine when switching is safe to execute. Rather than using a fixed time delay, the system continuously monitors pressure and switches as soon as the switch-over pressure threshold is reached, optimizing the balance between switching speed and component protection.
Solution Approach 2:
The switching timing is made dynamic rather than fixed. The system adapts the switching moment based on actual hydraulic conditions (discharge pressure levels), allowing the switching operation to occur as quickly as safety conditions permit, rather than waiting for a predetermined time interval regardless of pressure state.
3Reliability
If a pressure sensor and switch-over pressure detection are implemented, then component durability is protected, but the device complexity increases
Solution Approach 1:
The system uses the existing hydraulic pressure signal directly, detected by a pressure sensor, to control the switching operation. By leveraging the hydraulic system's own pressure state as the control signal basis, the invention avoids complex external sensing systems while reliably protecting components through pressure-based switching decisions.
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 prevents sudden pressure increases during rotation direction switching, ensuring the cooling fan can change directions smoothly without compromising the durability of hydraulic circuit components.
Implementation Method 1
a variable relief valve via which a discharge pressure at the hydraulic pump is controlled
Implementation Method 2
a pressure sensor that detects the discharge pressure at the hydraulic pump
Implementation Method 3
a direction switching valve that causes the hydraulic motor to rotate in a forward direction or in a reverse direction by switching direction of a flow of oil discharged from the hydraulic pump
Implementation Method 4
a hydraulic motor that is driven with pressure oil discharged from the hydraulic pump and rotates a cooling fan
Data Source
AI summary
A cooling fan control unit, in response to an operation performed at the rotation direction selector switch to select a reverse rotation setting while the cooling fan is rotating forward, lowers a relief pressure setting at the variable relief valve to a predetermined lower limit value over a predetermined length of time, and once the discharge pressure at the hydraulic pump detected by the pressure sensor is lowered to a predetermined switch-over pressure, executes control so as to switch the direction of flow of pressure oil to the hydraulic motor to the reverse direction by switching the direction switching valve and raises the relief pressure setting at the variable relief valve to a reverse rotation pressure setting, at which the hydraulic motor rotates in the reverse direction, over a predetermined length of time.