Fluid Pressure Control Device for Lock-Up Clutch Shock Suppression
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Solution Overview
Problem
The engagement of the lock-up clutch in torque converters often results in engagement shocks due to excessive discharge of working oil from the disengagement oil chamber, especially when the rotational speed difference between input and output is large, leading to increased centrifugal oil pressure that depresses the clutch excessively.
Innovation Solution
A fluid pressure control device with a signal pressure output valve and a control valve that regulates fluid pressure to prevent unnecessary discharge from the disengagement oil chamber, maintaining a supply/discharge-disabled state to confine working oil and resist clutch depression, thereby suppressing engagement shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lock-up clutch is engaged by discharging working oil from the disengagement oil chamber, then the clutch engagement speed increases, but engagement shock occurs due to excessive discharge rate
Solution Approach 1:
The control valve operates in periodic cycles, switching between states that allow and block oil discharge. By controlling the timing and duration of discharge phases, the system achieves controlled engagement speed while preventing excessive discharge rates that cause shock.
Solution Approach 2:
The control valve uses feedback from the disengagement oil chamber pressure to regulate the discharge rate. When pressure exceeds a threshold, the valve restricts discharge, preventing excessive engagement speed and resulting shock.
2Ease of operation
If a control valve is added to regulate hydraulic pressure in the disengagement oil chamber, then clutch engagement smoothness improves, but device complexity increases
Solution Approach 1:
The control valve performs multiple functions: regulating disengagement oil chamber pressure, controlling engagement timing, and preventing engagement shock. By consolidating these functions into a single component, the system achieves smooth engagement without proportionally increasing complexity.
Solution Approach 2:
The control valve automatically regulates pressure based on feedback from the system state, without requiring external control signals. This self-regulating capability simplifies the overall control architecture while maintaining engagement smoothness.
3Productivity
If working oil is discharged from the disengagement oil chamber to engage the clutch, then clutch engagement is achieved, but unnecessary discharge causes excessive clutch depression
Solution Approach 1:
The control valve allows partial discharge of working oil rather than complete discharge. By controlling the discharge rate and duration, the system achieves sufficient clutch engagement while preventing excessive depression that would reduce engagement efficiency.
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 suppresses engagement shocks by maintaining the working oil in the disengagement oil chamber, ensuring smooth clutch engagement and reducing the risk of excessive clutch depression, even under high centrifugal oil pressures.
Implementation Method 1
a larger feedback force that urges discharge of a larger amount of the working oil from the disengagement oil chamber acts as a higher hydraulic pressure acts on the disengagement oil chamber
Implementation Method 2
a centrifugal oil pressure produced in the working oil in the engagement oil chamber on the input shaft side is increased because of the difference in rotational speed
Data Source
AI summary
A fluid pressure control device controls input and output of a fluid pressure to and from a fluid chamber in a device that transfers power from a motor via working fluid in the chamber, the chamber being partitioned into engagement and disengagement oil chambers by a lock-up clutch. A signal pressure output valve performs pressure regulation to output a signal pressure. The control device includes a control valve connected to an output source flow passage leading to an output source of the fluid pressure, and a control unit controlling the signal pressure output valve so the control valve establishes a first state when the lock-up clutch is turned off, establishes a third state when the lock-up clutch is turned on, and establishes a second state so the working fluid can be confined in the disengagement oil chamber when the lock-up clutch is switched on.