Automatic Transmission Gear Shifting Control Using Multiple RPM Factors
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Solution Overview
Problem
Conventional automatic transmission systems for hybrid vehicles can only use one control factor, such as transmission inlet speed, to control the engagement and release of friction elements, limiting precise control and simultaneous individual control of hydraulic pressures during gear shifting, especially in continuously variable transmission systems where input and output speeds vary.
Innovation Solution
The method involves selecting at least two control factors, including rpm of a turbine, first motor generator (MG1), and second motor generator (MG2), and planetary gear set rpm, to set different synchronous speeds for controlling the engagement and release of friction elements, allowing simultaneous and individual control of hydraulic pressures applied to the friction elements during gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only one control factor (transmission inlet speed) is used to control gear shifting, then the control system is simple, but precise control of friction element engagement and release is limited
Solution Approach 1:
The patent segments the single control factor into multiple control factors (turbine rpm, MG1 rpm, MG2 rpm, planetary gear set rpm). Each control factor is used to control specific friction elements independently, enabling precise control of engagement and release timing for each friction element during gear shifting.
Solution Approach 2:
The patent transitions from one-dimensional control (single control factor) to multi-dimensional control by introducing multiple control factors operating in different dimensions. This allows simultaneous and individual control of hydraulic pressures for different friction elements, resolving the limitation of precise control while managing system complexity through structured multi-factor coordination.
2Ease of operation
If friction elements are controlled consecutively rather than simultaneously, then control is simpler, but simultaneous individual control of hydraulic pressures is difficult
Solution Approach 1:
The patent applies preliminary action by pre-setting synchronous speeds for each friction element based on multiple control factors before gear shifting occurs. This allows the control system to prepare the timing and hydraulic pressure profiles in advance, enabling simultaneous and precise control of multiple friction elements during the actual gear shifting event.
3Adaptability or versatility
If only transmission inlet speed is used as control factor, then control is straightforward, but control of friction elements is impossible in ECVT systems where input and output speeds vary
Solution Approach 1:
The patent makes the control system universal by applying multiple control factors that can adapt to different transmission types (step-type automatic transmission and ECVT). The same multi-factor control approach works for both fixed-ratio and variable-ratio systems, enabling the system to handle varying input and output speeds in ECVT while maintaining control precision.
Data Source
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AI summary
Disclosed herein is a method for controlling gear shifting of an automatic transmission from an N gear stage to an N' gear stage. The gear shifting is embodied by means of engaging and releasing friction elements. The method includes selecting at least two among an rpm of a turbine, an rpm of a first motor generator (MG1), an rpm of a second motor generator (MG2) and an rpm of a planetary gear set as control factors, and controlling engagement and release of the friction elements using the control factors.