Hybrid Vehicle Control Device for Simultaneous Engine Startup and Downshifting
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Solution Overview
Problem
Conventional hybrid vehicle control devices face challenges in managing drive force during engine startup and downshifting, as engine startup control is prioritized over downshifting, leading to delayed achievement of intended drive force and difficulty in preventing draw shock when timings overlap.
Innovation Solution
A control device that processes engine startup and downshifting simultaneously by maintaining a slip-engaged state with the second clutch during engine startup, allowing the motor torque to increase input speed and complete downshifting before engine startup is fully completed, using the second clutch to manage torque fluctuations and prevent shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine startup control is performed first and downshifting control is stopped during engine cranking, then engine startup can be completed reliably, but the time required for downshifting increases and drive force achievement is delayed
Solution Approach 1:
The patent merges engine startup control and downshifting control into a simultaneous processing operation. The control device executes both controls in parallel by coordinating the cranking operation with the shifting operation, allowing the engaged element to be engaged during engine cranking while completing downshifting, thereby reducing total time without compromising startup reliability
Solution Approach 2:
The patent applies preliminary action by pre-positioning the engaged element before engine startup is complete. The control device determines synchronization of the first clutch in advance and prepares the downshifting engaged element engagement to occur during the cranking process, rather than waiting for cranking to finish before initiating downshifting
2Measurement precision
If downshifting control is stopped during engine startup cranking, then clutch synchronization can be properly determined, but the progress of downshifting is delayed and drive force is not achieved promptly
Solution Approach 1:
The control device uses feedback mechanisms to monitor the synchronization state of the first clutch during simultaneous processing. By continuously determining clutch synchronization status and adjusting the control strategy accordingly, the system maintains measurement precision while enabling continuous progress of downshifting control through coordinated engagement timing
3Ease of operation
If the second clutch is disengaged during engine startup, then torque transmission can be controlled, but drive force management becomes difficult and draw shock may occur
Solution Approach 1:
The patent applies dynamics by maintaining the second clutch in a slip-engaged state during simultaneous processing rather than a fixed engaged or disengaged state. This dynamic slip-engaged condition allows the second clutch to accommodate torque fluctuations during engine cranking while progressively transmitting drive force, preventing draw shock and maintaining stable drive force management throughout the transition
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 approach reduces the time required for downshifting and enables effective drive force management, ensuring the intended drive force is achieved quickly and smoothly, even under high acceleration requests, while preventing draw shock.
Implementation Method 1
the motor has a drive motor function as well as an engine startup motor function
Implementation Method 2
a first clutch disposed between the engine and the motor/generator
Implementation Method 3
the second clutch maintains a slip-engaged state during engine startup control
Data Source
Figure 1
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AI summary
When engine startup and downshifting are processed in parallel while a vehicle is traveling, not only can the time required from the start of downshifting to the end of downshifting be shortened, but downshifting control that prevents draw shock can be easily performed. A control device of an FR hybrid vehicle comprises an engine (Eng), a motor/generator (MG), a first clutch (CL1), an automatic transmission (AT), a second clutch (CL2), and startup/shifting simultaneous processing means (FIG. 6). When engine speed increase control for increasing the engine speed by the motor/generator (MG) in order to start up the engine during travel and downshifting control of the automatic transmission (AT) are processed in parallel, the startup/shifting simultaneous processing means (FIG. 6) uses the motor torque of the motor/generator (MG) to increase the increase of input speed by the downshifting control to a target input speed while engine speed increase control is being performed by the motor/generator (MG).