Hybrid Vehicle Engine Speed Control for Fuel Injection Delay
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Solution Overview
Problem
In hybrid vehicles, when the engine is motored by a first motor at a rotation speed higher than the upper limit during fuel cutting, it takes a long time for the engine to reach the upper limit rotation speed for fuel injection to start, leading to a delay in driving force output and a slow feel for the driver.
Innovation Solution
The hybrid vehicle employs a control device that decreases the engine rotation speed using the first motor until it reaches the upper limit rotation speed, thereby shortening the time to initiate fuel injection and output driving force through the planetary gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is motored by the first motor at a rotation speed higher than the upper limit during fuel cutting, then the engine can operate at high rotation speeds, but it takes a long time for the engine to reach the upper limit rotation speed for fuel injection to start, leading to a delay in driving force output
Solution Approach 1:
The control device performs preliminary action by controlling the first motor to decrease the engine rotation speed to the upper limit rotation speed before fuel injection is started. This preliminary speed adjustment ensures that when fuel injection begins, the engine is already at the optimal rotation speed, eliminating the delay that would otherwise occur while waiting for the engine to naturally decelerate to the upper limit speed.
2Loss of time
If the engine rotation speed is decreased by the first motor to reach the upper limit rotation speed, then the time to initiate fuel injection is shortened, but the control system becomes more complex
Solution Approach 1:
The first motor is designed with multi-functionality, serving both as a propulsion motor during normal operation and as a speed control device during fuel cutting transitions. By utilizing the existing first motor for the additional function of decreasing engine rotation speed to the upper limit, the invention avoids adding separate control mechanisms, thereby minimizing the increase in control system complexity while achieving the goal of shortening the time to initiate fuel injection.
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 configuration reduces the time to reach the upper limit rotation speed and initiates fuel injection sooner, preventing the driver from feeling slow by expediting the driving force output to the driveshaft.
Implementation Method 1
a first motor configured to input and output power to and from the sun gear
Implementation Method 2
a planetary gear including three rotational elements that are respectively connected with an output shaft of the engine, a rotating shaft of the first motor and a driveshaft which is coupled with an axle
Data Source
AI summary
There is provided a hybrid vehicle that suppresses the driver from feeling slow. At the time of a predetermined request that requires fuel injection of an engine in the state of motoring the engine under fuel cutting by a first motor at a rotation speed that is higher than an upper limit rotation speed during fuel injection of the engine, the hybrid vehicle waits until the rotation speed of the engine becomes equal to or lower than the upper limit rotation speed and then starts fuel injection of the engine. At the time of the predetermined request, the hybrid vehicle causes the rotation speed of the engine to be decreased by the first motor until the rotation speed of the engine becomes equal to or lower than the upper limit rotation speed.