Vehicle Control Device for Turbocharged Engine Supercharging Delay
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Solution Overview
Problem
Turbocharged engines with continuously variable transmissions experience supercharging delays when torque is reduced, leading to discomfort during drive due to delayed intake air pressure recovery and torque rise.
Innovation Solution
A control device that includes a driver request torque detection unit, restriction torque calculation unit, and corrected torque calculation unit, which control the throttle valve and exhaust bypass valve based on driver requests and external conditions to manage torque reduction and prevent supercharging delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the waste gate valve is opened to lower the supercharging pressure during step-up shift control, then the target air charging efficiency is reduced to prevent excessive torque, but the intake air pressure does not rise immediately after the valve is closed, causing supercharging delay
Solution Approach 1:
The control device performs preliminary action by controlling the throttle valve to increase intake air amount in advance before the waste gate valve is closed. This preliminary increase in intake air supply ensures that when the waste gate valve closes and supercharging pressure needs to rise, the system is already prepared with increased air flow, thereby reducing the supercharging delay time.
Solution Approach 2:
The control device applies preliminary anti-action by counteracting the potential negative effect (supercharging delay) before it occurs. By advancing the throttle valve control to increase intake air amount prior to waste gate valve closure, the system pre-compensates for the pressure recovery delay, effectively neutralizing the timing issue before it manifests as a performance problem.
2Ease of operation
If the transmission gear ratio is decreased during acceleration, then the engine rotation speed is lowered to provide step-up shift feeling, but excessive torque may cause the driver to experience uncomfortable push-forward sensation
Solution Approach 1:
The control device changes parameters by adjusting both the transmission gear ratio and the engine's air charging efficiency (through waste gate valve and throttle valve control). By coordinating these parameter changes, the system achieves the desired step-up shift feeling while simultaneously managing torque output to prevent excessive force that would cause uncomfortable push-forward sensation.
Solution Approach 2:
The control device applies dynamics by making the system adaptable and adjustable in real-time. The control unit dynamically adjusts the waste gate valve opening degree and throttle valve position based on the transmission gear ratio changes, enabling the system to respond flexibly to varying drive conditions and maintain optimal torque levels throughout the step-up shift process.
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 control device effectively suppresses supercharging delays by adjusting valve positions to maintain optimal air charging efficiency, ensuring smoother torque delivery and improved drive comfort during torque reduction requests.
Implementation Method 1
a turbocharger having an exhaust gas turbine which is disposed in the exhaust passage and driven by an exhaust gas flowing through the exhaust passage and a compressor which is disposed in the intake passage and supercharges intake air
Implementation Method 2
an exhaust bypass valve for opening or closing an exhaust bypass passage that connects portions, upstream of and downstream of the exhaust gas turbine, of the exhaust passage
Implementation Method 3
a throttle valve disposed in the intake passage
Data Source
AI summary
A control device for a vehicle includes a driver request torque detection unit that detects a driver request torque, a restriction torque calculation unit that calculates a restriction torque being smaller than the driver request torque based on an external request, a corrected torque calculation unit that calculates a corrected torque being greater than the restriction torque, and an engine control unit that controls positions of a throttle valve and an exhaust bypass valve. The engine control unit controls the positions of the throttle valve and the exhaust bypass valve based on the driver request torque during an ordinary drive, and if a prescribed drive condition is satisfied, the engine control unit controls the position of the throttle valve based on the restriction torque and controls the position of the exhaust bypass valve based on the corrected torque.