Vehicle Control Unit Port Multiplexing for Engine Stop Switch Detection
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Solution Overview
Problem
The limited number of ports in vehicle control units restricts the increase in functions, making it difficult to accommodate additional external devices effectively, particularly in the case of the engine stop instruction switch.
Innovation Solution
A vehicle control device that utilizes a relay with a contact part to connect and disconnect power to an electric pump, incorporating an engine stop instruction switch between the power source and the relay's coil part, and a control unit that determines the operation of the switch using a detection part with an amplifier circuit, eliminating the need for a dedicated port and allowing for fault diagnosis of connected devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated port is provided for the engine stop instruction switch, then the switch operation can be reliably detected, but the number of available ports decreases and functional expansion is restricted
Solution Approach 1:
The patent applies multi-functionality by enabling the port to serve dual purposes: it functions as both a power supply output port for the relay coil and an input port for detecting the engine stop instruction switch operation. This is achieved by using the same port for both driving the relay and detecting the switch state, eliminating the need for a separate dedicated port while maintaining reliable detection capability.
2Device complexity
If the detection part directly measures current at the port, then the circuit is simple, but weak currents cannot be reliably detected
Solution Approach 1:
The patent introduces an amplifier circuit as an intermediary component between the port and the detection part. The amplifier circuit receives the weak current signal from the port, amplifies it to a usable level, and then the detection part can reliably measure the amplified signal. This intermediary approach enables precise detection of weak currents while maintaining reasonable circuit complexity.
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 the determination of the engine stop instruction switch operation without a dedicated port, enhances the detection of weak currents, and facilitates fault diagnosis of fuel injection and ignition coils independently of the engine stop switch state, ensuring reliable operation and efficient use of ports.
Implementation Method 1
an amplifier circuit (35b) that converts the current to a voltage to amplify the voltage and output the amplified voltage
Implementation Method 2
a shunt resistor (35a) that is connected to the drive part (34) and through which a current flowing through the coil part (2b) flows
Data Source
AI summary
A vehicle control device for controlling an engine and an electric pump includes a relay having a contact part for connecting and disconnecting a power source to the electric pump, an engine stop instruction switch provided between the power source and a coil part of the relay for connecting and disconnecting the power source to and from the coil part. A control unit for controlling the engine and the relay and determining whether or not operation of the engine stop instruction switch is made. The control unit includes a port to which the coil part and a drive part are connected for switching current application of the coil part, a detection part for detecting a current flowing to the port, and a determiner for determining whether or not the operation of the engine stop instruction switch is made based on a detection result of the detection part.