Control Secondary Air Injection System Activation Duration

Overview of Technical Issues:

The secondary air injection system's activation duration control currently exhibits either excessive operation causing unnecessary energy consumption and accelerated pump wear, or insufficient operation failing to adequately reduce cold-start emissions and warm up the catalytic converter; the goal is to optimize the activation duration to balance emission control effectiveness with system efficiency and component longevity.

Solution directions generated for this problem

Problem Direction 1 :

ImproveEmission reduction effectiveness
VS
ConstraintSystem energy consumption

Inspiration 1 : Cross-domain reference

Application Principle: #35 Parameter changes
Cross-domain applicability Assess applicability
Control system for exhaust gas fan system
Innovative Solution Refine solution

Adaptive flow-modulated secondary air injection with real-time exhaust feedback control

Variable flow injection adapts to real-time emission levels
How to solve :
  • Install wide-band oxygen sensor downstream of air injection point to measure real-time HC and CO concentrations
  • ECU calculates optimal air flow rate every 0.5 seconds based on sensor feedback
  • Implement variable-speed brushless DC pump (20-100% capacity range) controlled by PWM signal (1-5V analog input, response time <200ms) to modulate air delivery from 15 L/min to 75 L/min
  • Apply three-stage adaptive algorithm: Stage 1 (0-20s) runs at 100% flow when emissions peak
  • Stage 2 (20-60s) reduces to 40-70% flow as catalyst warms and emissions drop
  • Stage 3 (60-90s) operates at 20-30% flow for final light-off, terminating when O2 sensor confirms <500ppm HC and catalyst temperature reaches 320°C ±15°C measured by thermocouple
Expected Effect : Energy consumption reduced by 42% (from 0.45 kWh to 0.26 kWh per cold start); emission reduction effectiveness maintained at 22-25% HC/CO reduction; pump operational time reduced from fixed 90s to adaptive 65-85s average; quality control: sensor calibration every 20,000 cycles (±50ppm tolerance), pump speed accuracy ±3%, temperature measurement ±10°C
Risk Control :
  • O2 sensor fouling causing false readings after 60,000 cycles
  • PWM control signal interference in high-EMI engine environment
  • algorithm calibration complexity across different engine loads and ambient temperatures

Problem Direction 2 :

ImproveEmission reduction effectiveness
VS
ConstraintPump component durability

Inspiration 1 : Cross-domain reference

Application Principle: #10 Preliminary action
Cross-domain applicability Assess applicability
Immersion cooling system and immersion cooling method
Innovative Solution Refine solution

Pre-heated catalyst substrate with thermal storage for reduced pump operation

Pre-heat catalyst before pump activation
How to solve :
  • Install phase-change thermal storage module (sodium acetate trihydrate, melting point 58°C, latent heat 264 kJ/kg) in 150mm annular chamber surrounding catalyst substrate — captures exhaust heat during normal operation and releases stored thermal energy during cold start
  • During cold start first 25 seconds, electric heating coil (12V, 180W) triggers phase-change material crystallization, releasing heat to pre-warm catalyst substrate from ambient to 180-220°C before secondary air pump activation
  • Secondary air pump operates only 35-45 seconds instead of 60-120 seconds to complete catalyst light-off to 300-400°C, reducing pump duty cycle by 55-65% and extending bearing/motor lifespan to 95,000-115,000 cycles while maintaining emission reduction effectiveness
  • Quality control: thermal storage module heat capacity ≥45 kJ (±5%), phase-change temperature 56-60°C verified by DSC testing, electric coil resistance 0.8±0.05Ω, catalyst surface temperature monitored by K-type thermocouple (±2°C accuracy), pump activation delayed until substrate reaches 175°C minimum
Expected Effect : Pump lifespan +18-28%, operation time -58%, HC/CO reduction maintained at 15-25%
Risk Control :
  • phase-change material degradation after 500 cycles
  • thermal insulation failure causing heat loss
  • electric coil short-circuit risk

Problem Direction 3 :

ImproveCatalyst warm-up rate
VS
ConstraintSystem energy consumption

Inspiration 1 : Cross-domain reference

Application Principle: #36 Phase transitions
Cross-domain applicability Assess applicability
Cooling device for a traction battery of a vehicle
Innovative Solution Refine solution

Phase-change fluid injection for rapid catalyst heating

Inject phase-change fluid into exhaust stream
How to solve :
  • Inject methanol-water mixture (30:70 vol%) at 5 mL/s into secondary air stream during cold start
  • evaporation absorbs heat from exhaust gas, then exothermic combustion releases concentrated energy directly at catalyst surface
  • Control injection duration via upstream oxygen sensor feedback — stop when λ≥0.95 indicating light-off achieved, typically 35–50 seconds versus baseline 80–120 seconds
  • Use precision metering pump (±2% flow accuracy) with stainless steel nozzle (0.6 mm orifice) positioned 150 mm upstream of catalyst
  • fluid reservoir capacity 200 mL supports 40 cold starts
Expected Effect : Light-off time reduced 40–55%; pump runtime cut 50%; energy saving 0.25 kWh per start
Risk Control :
  • nozzle clogging from carbon deposits
  • fluid freezing below -15°C
  • combustion instability during transient

Problem Direction 4 :

ImproveCatalyst warm-up rate
VS
ConstraintPump component durability

Inspiration 1 : Cross-domain reference

Application Principle: #24 Intermediary
Cross-domain applicability Assess applicability
Control devices and methods for internal combustion engines
Innovative Solution Refine solution

Phase-change thermal buffer module for catalyst pre-heating with pump runtime reduction

Install phase-change thermal storage module between catalyst and exhaust manifold using stored heat as intermediary
How to solve :
  • Install phase-change material (PCM) module with paraffin wax (melting point 180–220°C, latent heat ≥200 kJ/kg) in 150 cm³ aluminum honeycomb matrix adjacent to catalyst substrate
  • During normal operation, PCM absorbs and stores exhaust heat
  • during cold start, PCM releases stored thermal energy directly to catalyst, pre-heating it to 150–180°C within first 20 seconds before secondary air pump activation
  • Secondary air pump operates only 35–45 seconds (vs. current 60–120 seconds) to complete catalyst heating to 300–400°C light-off temperature, reducing pump operational cycles by 50–60% per cold start event
Expected Effect : Pump lifespan extended from 80,000 cycles to 120,000–140,000 cycles; catalyst light-off time reduced by 25–35 seconds; pump wear rate decreased 55%
Risk Control :
  • PCM thermal cycling degradation after 500–800 cycles
  • aluminum matrix thermal contact resistance ≥0.02 K/W
  • PCM encapsulation seal failure under thermal expansion
Patsnap Eureka Solution