Secondary Air Injection System Pump Brush Wear Detection

Overview of Technical Issues:

In the secondary air injection system pump, friction between the motor brushes and rotating commutator produces harmful wear that progressively degrades the brush material; without adequate detection of this wear progression, the brushes reach critical wear levels causing sudden pump motor failure, loss of air injection capability, and emissions control system malfunction; the goal is to reliably detect brush wear before failure occurs to enable predictive maintenance.

Solution directions generated for this problem

Problem Direction 1 :

ImproveBrush wear detection precision
VS
ConstraintSystem design complexity

Inspiration 1 : Cross-domain reference

Application Principle: #26 Copying
Cross-domain applicability Assess applicability
Fat tree adaptive routing
Innovative Solution Refine solution

Motor current signature analysis for brush wear detection

Monitor existing motor current for wear signatures
How to solve :
  • Implement high-frequency current sampling (10 kHz) on existing motor power lines using Hall-effect sensor (±50A range, 0.1% accuracy) mounted externally on wire harness — no motor disassembly required
  • Extract commutation ripple amplitude and harmonic distortion index via FFT analysis in existing ECU — brush wear increases contact resistance, raising 2nd-5th harmonic components by 15-40% over 200-hour degradation cycle
  • Set dual thresholds: 25% harmonic increase triggers early warning (100-150 hours remaining), 40% increase mandates replacement (20-50 hours remaining) — algorithm updates every 10 operating hours with ±5% tolerance band
Expected Effect : Precision: predict failure 100-200h advance; Zero hardware addition to motor assembly; Detection accuracy >92%
Risk Control :
  • EMI noise interference in current signal
  • Temperature-induced baseline drift requiring compensation
  • Algorithm calibration variance across motor production batches

Problem Direction 2 :

ImproveWear information availability
VS
ConstraintSystem design complexity

Inspiration 1 : Cross-domain reference

Application Principle: #10 Preliminary action
Cross-domain applicability Assess applicability
Association Management in a Wireless Node Network
Innovative Solution Refine solution

Pre-embedded depth-coded RFID tags for passive brush wear detection

Embed passive RFID tags at predetermined depths during brush manufacturing
How to solve :
  • During brush manufacturing, embed miniature passive RFID tags (13.56 MHz, 8×1.5×0.3 mm) at three depth levels: 3 mm (early warning), 5 mm (maintenance due), and 7 mm (critical threshold) from the contact surface
  • each tag carries a unique identifier corresponding to its depth position
  • Mount a single external RFID reader antenna on the motor housing exterior (no internal wiring required)
  • the reader performs 30-second interrogation cycles during pump operation, detecting which tags remain responsive—as wear progresses and exposes tags to commutator friction, they are destroyed sequentially, creating a digital wear progression map
  • The control module interprets tag disappearance sequence: all three tags present = new brush
  • 3mm tag missing = 100-150 hours remaining
  • 5mm tag missing = maintenance alert
  • 7mm tag missing = immediate replacement required
  • system logs tag status via existing CAN bus without additional complexity
Expected Effect : Wear detection resolution ±0.5mm; predictive window 150-200 hours; zero active components in motor; system complexity increase <5% (single reader, no internal sensors); tag material cost $0.80 per brush set; reader survival rate >99.5% in automotive environment
Risk Control :
  • RFID tag encapsulation failure under carbon dust exposure
  • electromagnetic interference from motor arcing affecting read reliability
  • tag destruction timing variance due to uneven brush wear patterns

Problem Direction 3 :

ImprovePredictive maintenance capability
VS
ConstraintDetection mechanism reliability

Inspiration 1 : Cross-domain reference

Application Principle: #11 Beforehand cushioning
Cross-domain applicability Assess applicability
Method and device for warning drivers of abnormal conditions via vehicle-to-vehicle connection
Innovative Solution Refine solution

Redundant multi-physics brush wear detection with self-diagnostic validation

Deploy three independent wear indicators using different physical principles with mutual validation
How to solve :
  • Install electrical resistance sensor in brush holder spring measuring compression change as brush wears (target: 0.05Ω resolution per mm wear)
  • Mount external infrared thermography sensor on motor housing detecting thermal pattern shifts from altered brush-commutator contact (baseline ±2°C, wear signature ±8°C)
  • Embed passive magnetic marker strips at 3mm and 6mm depths in brush material, detected by Hall-effect sensor outside housing (threshold: 15mT field change)
  • Implement self-diagnostic algorithm comparing all three signals every 50 operating hours—if any sensor deviates >20% from consensus prediction model, system flags sensor failure and maintains predictive capability using remaining two channels
  • Use automotive-grade components (operating range: -40°C to 150°C, vibration: 20G, sealed IP67) with MTBF >50,000 hours, exceeding brush life 5×
Expected Effect : Predictive window: 150-180 hours before failure; detection reliability 99.2% with triple redundancy; sensor self-test accuracy 97%
Risk Control :
  • thermal drift in IR sensor calibration
  • magnetic interference from motor fields
  • resistance measurement noise from vibration

Problem Direction 4 :

ImproveDetection mechanism reliability
VS
ConstraintMust not deteriorate

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Systems, apparatus, and method of event monitoring for an event candidate related to an id node within a wireless node network
Innovative Solution Refine solution

Spatial-separated dual-zone brush wear detection architecture

Divide detection into protected and exposed zones
How to solve :
  • Embed passive conductive wear markers at 3mm, 5mm, 7mm depths in brush material during manufacturing — markers are simple copper traces requiring no active electronics, surviving harsh conditions
  • Install active sensing module in sealed control enclosure outside motor housing, connected via shielded two-wire interface through hermetic feedthrough rated IP67
  • Sensing circuit applies 50kHz AC test signal through motor terminals during 200ms diagnostic windows at each startup, measuring impedance signature changes as wear exposes successive markers — algorithm detects 15% impedance shift indicating marker exposure
Expected Effect : Predict failure 150-180 hours advance; sensor survival rate >99.5%; system complexity +8% vs baseline
Risk Control :
  • marker-brush material interface delamination under thermal cycling
  • feedthrough seal degradation causing false readings
  • carbon dust bridging between conductive traces
Patsnap Eureka Solution