Automatic Transmission Clutch Neutral Control for Drag Loss Reduction
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Solution Overview
Problem
Conventional automatic transmission control devices experience drag loss and delay in clutch engagement when the vehicle is stopped, leading to suboptimal fuel economy and a sense of incongruity during start-off, despite improvements in linear solenoid valve performance.
Innovation Solution
A control device that includes range determination, vehicle stop detection, neutral control, start-off intent detection, fast-fill control, and engagement control mechanisms, utilizing a solenoid valve to adjust clutch engagement pressure, ensuring the clutch is disengaged without drag and quickly engaged upon start-off, considering oil temperature and pressure command values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clutch is fully disengaged during neutral control to eliminate drag loss, then fuel economy is improved, but clutch engagement delay occurs when the driver performs start-off operation
Solution Approach 1:
The system performs preliminary action by pre-filling the hydraulic oil chamber with oil during neutral control, so that when start-off is detected, the clutch can engage immediately without waiting for oil to fill the chamber. This resolves the contradiction by preparing the system in advance, eliminating engagement delay while maintaining full disengagement for fuel economy.
Solution Approach 2:
The system dynamically adjusts the clutch engagement pressure based on detected driver intent. When start-off is detected, the control device rapidly increases engagement pressure from zero to full pressure, transitioning from a static disengaged state to a dynamic engagement state. This resolves the contradiction by making the system adaptive rather than fixed.
2Device complexity
If conventional linear solenoid valve is used to control clutch engagement pressure, then system complexity is reduced, but response time for clutch state control is insufficient
Solution Approach 1:
The system replaces the conventional mechanical hydraulic control with an electronically controlled solenoid valve system. The solenoid valve receives electrical signals from the control device to directly control hydraulic pressure, substituting electronic control for traditional mechanical linkages. This resolves the contradiction by using electronic actuation to achieve fast response while maintaining relatively simple hydraulic hardware.
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 eliminates drag loss in the clutch during neutral control, achieving fuel economy comparable to manual shifting and reduces clutch engagement delay, providing a smooth start-off experience by accurately setting the clutch state prior to engagement.
Implementation Method 1
a control device (1) of an automatic transmission (3) that commands and controls a solenoid valve (SLC1) capable of adjusting and outputting an engagement pressure (PC1) to be delivered to a hydraulic oil chamber (46) of a hydraulic servo (40)
Implementation Method 2
commands and controls the engagement pressure (PC1) so as to achieve a state in which a piston (43) of the clutch (C-1) contacts a clutch drum (42) by a biasing force of a spring (45)
Implementation Method 3
a state in which oil fills an oil passage (50) from the solenoid valve (SLC1) to the hydraulic oil chamber (46) of the hydraulic servo (40) of the clutch (C-1)
Data Source
AI summary
If it is determined that a D range is in use and determined that a vehicle is stopped, neutral control means (25) commands and controls an engagement pressure of a clutch (C-1) so as to achieve a state in which a piston of the clutch (C-1) contacts a clutch drum by a biasing force of a spring, and a state in which oil fills an oil passage from a linear solenoid valve (SLC1) to a hydraulic oil chamber and fills the hydraulic oil chamber. There is thus no drag loss in the clutch (C-1) during a neutral control, and the same fuel economy as when, for example, a manual shift to the neutral range is made can be achieved during the neutral control.