Starter Relay Control Circuit with Self-Diagnosis

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional starter-relay control circuits face difficulties in detecting specific failure modes, such as 'STA+terminal battery short' and 'high-side transistor on-fault', which can lead to undetected faults and continued vehicle operation with potential safety risks.

Innovation Solution

A starter-relay control circuit with a high-side terminal and low-side terminal connected to the starter relay coil, incorporating a high-side switching element, low-side switching element, pull-up and pull-down elements, and a failure detecting unit that monitors voltage levels to distinguish between normal and faulty states, including detecting 'STA+terminal battery short' and 'high-side transistor on-fault' by analyzing the output signals when the ignition switch is off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional starter-relay control circuits are used, then the basic engine starting function is achieved, but specific failure modes such as 'STA+terminal battery short' and 'high-side transistor on-fault' cannot be detected

Engineering Contradiction:

Improvefailure detection capabilityVSAvoidcontrol circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control circuit performs preliminary diagnostic actions by monitoring voltage levels at specific terminals before normal operation. The failure detecting unit continuously monitors voltage levels at the high-side and low-side terminals, enabling early detection of potential failures such as battery shorts or transistor faults before they affect engine starting.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A failure detecting unit is introduced as an intermediary component between the starter relay control circuit and the diagnostic system. This unit includes voltage level detection circuits that monitor terminal voltages and provide diagnostic information, enabling failure detection without significantly complicating the main control circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the control circuit monitors voltage levels to detect failures, then failure detection precision is improved, but the complexity of the control circuit increases

Engineering Contradiction:

Improvevoltage level detection accuracyVSAvoidcontrol circuit structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The voltage monitoring function is localized to specific critical points in the circuit - the high-side terminal and low-side terminal of the starter relay coil. By concentrating monitoring efforts at these specific locations rather than throughout the entire circuit, the patent achieves precise failure detection with minimal additional circuit complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system detects failures by monitoring changes in voltage parameters at key terminals. The failure detecting unit compares voltage levels against expected ranges to identify anomalies such as battery shorts or transistor failures, enabling precise measurement without requiring complex diagnostic equipment.

Inventive Principle:

Principle #35Parameter changes

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

Enhances the ability to detect various failure modes, particularly 'STA+terminal battery short' and 'high-side transistor on-fault', ensuring proper engine starting and preventing continued operation with undetected faults, thereby improving vehicle safety and maintenance efficiency.

Implementation Method 1

energization of a coil of a starter relay turns the starter relay on

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a pull-up element connected between the ignition power line and the first output line, and a pull-down element connected between the ground line and the second output line

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

a failure detecting unit connected to the first and second output lines and configured to determine whether a failure wherein the high-side terminal is short-circuited to the positive terminal of the battery occurs based on a voltage of the second output line

Methodology Applied

Scientific EffectVoltage measurement: Ohm's Law

Data Source

PatentUS7312968B2Starter-relay control circuit with self fault diagnosis function

Publication Date: 2007.12.25 DENSO CORP

AI summary

In a starter-relay control circuit, a high-side switching element is connected between a first output line connected to a high-side terminal and an ignition power line connected to the ignition switch. A low-side switching element is connected between a second output line connected to a low-side terminal and a ground line connected to a negative terminal of the battery. A pull-up element is connected between the ignition power line and the first output line. A pull-down element is connected between the ground line and the second output line. A failure detecting unit is connected to the first and second output lines and configured to determine whether a failure wherein the high-side terminal is short-circuited to the positive terminal of the battery occurs based on a voltage of the second output line when the ignition switch is in an off position.