Hybrid Vehicle Virtual Gear Control for Manual Shifting
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Solution Overview
Problem
Hybrid electric vehicles with continuously variable transmissions lack the ability to provide discrete gear ratios, making it difficult for drivers to manually control engine speed and torque, unlike vehicles with discrete ratio transmissions.
Innovation Solution
Implementing a hybrid vehicle control strategy that utilizes a controller to simulate discrete ratio transmission operations by adjusting engine speed and torque through various driver interface elements, such as shift levers and selectors, and employing virtual gear numbers to manage torque and engine speed in response to driver inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuously variable transmission is used in a hybrid vehicle, then the transmission flexibility and range of gear ratios is improved, but the ability to provide discrete gear ratios for manual driver control deteriorates
Solution Approach 1:
The patent divides the continuous transmission ratio range into discrete virtual gear segments (first virtual gear, second virtual gear, etc.). Each virtual gear corresponds to a specific transmission ratio range, allowing the controller to select discrete operating points within the continuous CVT range. This segmentation enables manual driver control through virtual shift commands while maintaining the flexibility of continuous variable transmission.
Solution Approach 2:
The patent creates a virtual gear ratio model that copies the characteristics of discrete ratio transmissions. The controller uses virtual gear numbers and associated transmission ratio tables to simulate the behavior of physical discrete gears, providing drivers with familiar manual shifting experience without requiring actual discrete gear mechanisms.
2Ease of operation
If a controller simulates discrete ratio transmission operations in a hybrid vehicle with CVT, then driver interaction and sporty feel are improved, but the control logic complexity increases
Solution Approach 1:
The patent pre-calculates and stores transmission ratio tables for each virtual gear number before operation. The controller receives shift commands and automatically retrieves the corresponding pre-defined transmission ratios from these tables, avoiding complex real-time calculations. This preliminary preparation simplifies the control logic while maintaining realistic simulated gear shifting behavior.
Solution Approach 2:
The patent changes the control parameter from continuous transmission ratio to discrete virtual gear number. By using virtual gear numbers as the primary control parameter and deriving transmission ratios from pre-stored tables based on these numbers, the system simplifies driver interaction (simple up/down shift commands) while managing control complexity through parameter transformation.
Data Source
AI summary
A hybrid vehicle and method of control are disclosed. An internal combustion engine and at least one traction motor are operated such that the combined output torque corresponds to one of a plurality of output torque functions, each output torque function having a distinct output torque at a maximum value of accelerator pedal position for an associated vehicle speed. The output torque function is selected based on a virtual gear number. The virtual gear number varies in response to driver activation of shift selectors or automatically in response to changes in vehicle speed.