Vehicle Starter Motor Kickback Prevention via Ignition Prohibition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine starter devices for vehicles face challenges in preventing kickback during kick-starting, particularly due to the complexity and cost associated with dedicated sensors for crankshaft rotational speed measurement, and the delay in combustion chamber pressure rise after ignition, which complicates timing adjustments.
Innovation Solution
An engine starter device incorporating a three-phase brushless motor with a rotor sensor to detect reverse rotation and prohibit ignition when the crankshaft is near the compression top dead center, using the motor's stage identification and ignition delay time to prevent kickback without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated sensor is provided for detecting the rotational speed of the crankshaft, then the measurement precision of crankshaft rotational speed is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling the rotor sensor of the three-phase brushless motor to serve dual purposes: both controlling motor operation and detecting crankshaft rotational speed for kickback prevention. The rotor sensor's output signals are processed to determine motor stage and detect reverse rotation, eliminating the need for separate dedicated sensors and reducing overall device complexity while maintaining measurement capability
Solution Approach 2:
The system applies self-service by using the motor's own rotor sensor to provide the detection function previously requiring separate components. The rotor sensor automatically provides signals that are processed by the control unit to detect reverse rotation and prevent kickback, making the system self-sufficient without additional external sensors
2Power
If ignition is executed when the crankshaft is near the compression top dead center, then the power output is improved, but kickback occurs due to low rotational speed
Solution Approach 1:
The patent applies preliminary anti-action by detecting reverse rotation before it fully develops and prohibiting ignition when reverse rotation is detected. The control unit monitors motor stage changes and rotational speed, and preemptively prevents ignition that would cause kickback, thereby counteracting the harmful effect before it occurs while still allowing normal high-power ignition during forward rotation
Solution Approach 2:
The system applies feedback by continuously monitoring the rotor sensor output signals to determine motor stage and detect reverse rotation. The control unit uses this real-time feedback information to dynamically control ignition timing, prohibiting ignition when reverse rotation is detected and allowing it during normal forward rotation, thus optimizing power output while preventing kickback
3Measurement precision
If the ignition timing is adjusted to account for combustion chamber pressure delay, then the kickback prevention accuracy is improved, but the control complexity increases
Solution Approach 1:
The patent applies preliminary action by establishing predetermined criteria for kickback detection based on motor stage and rotational speed thresholds before operation. The control unit has pre-programmed conditions for detecting reverse rotation and prohibiting ignition, eliminating the need for complex real-time calculations and simplifying control while maintaining accurate kickback prevention
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 solution allows for effective prevention of kickback with a simple and cost-effective configuration by monitoring the motor's stage changes and rotational speed, ensuring appropriate ignition timing based on the crankshaft's position and pressure rise delay, thus enhancing engine stability during kick-starting.
Implementation Method 1
a rotor sensor, and the direction of a current flowing through each of the phases of the generator/starter is identified according to an output state of the rotor sensor
Implementation Method 2
a generator/starter that is connected to a crankshaft of an engine and rotates synchronously with the crankshaft, wherein the generator/starter is a three-phase brushless motor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is an engine starter device for vehicles that is capable of preventing kickback with a simple structure without providing a dedicated sensor for detecting the rotational speed of a crankshaft. A motor stage identification unit (801) identifies an angular range of an ACG starter motor (48) as a motor stage on the basis of the direction of a current flowing through each phase of the ACG starter motor (48). If a three-phase AC motor is adopted as the ACG starter motor (48), the motor stage is identified on the basis of a combination of the directions of the current flowing through each of U, V, and W phases. A reverse rotation detection unit (802) detects that the rotational direction of the crankshaft (40) is changed from forward rotation to reverse rotation on the basis of a change in the motor stage. An ignition prohibition unit (803) ignites the engine at a normal ignition timing as long as the engine rotates forward, and prohibits ignition of the engine when reverse rotation is detected by the reverse rotation detection unit (802).