Piezo Injector Test Device with Dummy Load and Polarity Signaling

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Solution Overview

Problem

Conventional common rail systems face challenges in accurately identifying faults in piezo injectors, as error messages from the control unit do not clearly indicate whether the issue lies with the injector, wiring harness, or control unit, leading to unclear troubleshooting and potential permanent damage from incorrect polarity connections.

Innovation Solution

A testing device with an equivalent electrical load, including a film capacitor and current-direction-dependent signaling using light-emitting diodes, simulates the piezo injector to determine if the fault is with the injector, wiring harness, or control unit, and ensures correct polarity connection, utilizing an additional module for versatility in testing different injectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If error messages from the control unit are used to diagnose faults, then fault detection is enabled, but the location of the error (injector, wiring harness, or control unit) cannot be clearly identified

Engineering Contradiction:
Improvefault detection accuracyVSAvoiderror location information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

An equivalent electrical load (dummy load) is introduced as an intermediary component to replace the actual piezo injector during testing. This dummy load includes a capacitor with matched capacitance and allows clear differentiation between injector faults, wiring harness faults, and control unit faults by providing a known good reference, thereby resolving the ambiguity in error location identification

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the piezo injector is tested in-situ in the common rail system, then the injector can be monitored, but the troubleshooting process becomes complex and time-consuming

Engineering Contradiction:
Improveinjector monitoring capabilityVSAvoidtroubleshooting time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The piezo injector is extracted from the complex common rail system and tested using a simplified standalone testing device. This extraction isolates the injector testing from the full system complexity, allowing rapid diagnosis without needing to access or analyze the entire common rail system, thereby significantly reducing troubleshooting time

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of operation

If the polarity connection of the piezo injector is not verified before testing, then the testing can proceed, but permanent damage may occur from incorrect polarity connections

Engineering Contradiction:
Improvetesting accessibilityVSAvoiddamage from incorrect polarity
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A polarity verification step is performed before the actual injector testing begins. The testing device checks the polarity of the connection to the piezo injector in advance, and only proceeds with testing if the polarity is correct. This preliminary action prevents permanent damage from incorrect polarity connections while maintaining ease of operation

Inventive Principle:
Principle #10Preliminary action

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 solution improves fault detection by clearly identifying defective components and preventing permanent damage from incorrect polarity connections, enabling precise troubleshooting and reducing the risk of replacing functional components.

Implementation Method 1

the signaling device comprises a light-emitting diode which is connected in parallel with the capacitor

Methodology Applied
Scientific EffectLight-emitting diode: Light Emitting Diode

Implementation Method 2

The equivalent electrical load includes a capacitor whose capacity is matched to the piezo injector to be tested

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

testing a piezo injector of a common rail system

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP1746277B1Apparatus and method for testing a piezoelectric injector
Publication Date: 2019.04.10 ROBERT BOSCH GMBH
  • EP1746277B1 patent drawingFigure 1~3

AI summary

The invention relates to a device and a method for testing a piezo injector of a common rail system. To improve fault detection, the test device (1) includes an electrical substitute load (8, 10) for the injector.