Sequential Clutch Engagement for Transmission Park Readiness
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Solution Overview
Problem
Shifting a transmission from park to reverse or drive can cause sudden acceleration or deceleration of internal components, leading to audible and tactile responses that detract from operator comfort and satisfaction.
Innovation Solution
A transmission system with three hydraulic clutches and a pump, controlled by a controller, which engages the clutches in a specific sequence to establish a parked-ready condition, reducing the suddenness of component movement by bringing internal components to a desired rotational speed before shifting, thereby minimizing audible and tactile responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If all three clutches are engaged simultaneously upon engine start, then the parked-ready condition is established quickly, but sudden acceleration or deceleration of internal components occurs causing audible and tactile responses that reduce operator comfort
Solution Approach 1:
The clutch engagement process is segmented into three distinct phases: first clutch engagement (responsive to engine start), second clutch engagement (after first clutch engagement), and third clutch engagement (after second clutch engagement and hydraulic pressure threshold). This segmentation allows each clutch to engage at different times, preventing simultaneous engagement of all three clutches and thereby eliminating sudden acceleration or deceleration of internal transmission components that causes audible and tactile responses.
Solution Approach 2:
The controller performs preliminary actions by engaging the first clutch immediately upon detecting engine start, then subsequently engaging the second clutch after the first clutch engagement, and finally engaging the third clutch after the second clutch engagement and hydraulic pressure threshold. This preliminary sequencing prepares the transmission system gradually, bringing internal components to desired rotational speeds before complete engagement, thus reducing harmful audible and tactile responses while still establishing the parked-ready condition efficiently.
2Object-affected harmful factors
If clutches are engaged in sequence to reduce sudden component movement, then operator comfort is improved, but the time to establish parked-ready condition increases
Solution Approach 1:
The controller implements periodic action by engaging clutches at specific intervals based on engine start detection and hydraulic pressure thresholds. The first clutch engages immediately upon engine start, the second clutch engages after a first period following first clutch engagement, and the third clutch engages after a second period following second clutch engagement and hydraulic pressure threshold. These periodic engagement timings are optimized to reduce sudden component movement and improve operator comfort while minimizing the total time to establish the parked-ready condition.
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 audible and tactile responses during gear shifts, enhancing operator comfort by smoothly preparing the transmission components for gear engagement, thus improving the overall driving experience.
Implementation Method 1
The pump is configured to generate hydraulic fluid pressure
Data Source
AI summary
A transmission includes a first hydraulic clutch, a second hydraulic clutch, a third hydraulic clutch, a pump and a controller. The first, second, and third hydraulic clutches are configured to established a parked-ready condition upon engagement of all three clutches. The pump is configured to generate hydraulic fluid pressure. The controller is programmed to, in response to a command to start an engine that powers the pump, engage the first and second clutches. The controller is further programmed to, in response to engagement of the first and second clutches and obtaining operating hydraulic fluid pressure, engage the third clutch.