Secondary Air Injection System Response Time Optimization

Overview of Technical Issues:

The secondary air injection system's control actuating mechanism and air delivery pathway exhibit insufficient response speed, causing delayed air injection during cold start—this prevents timely catalytic converter light-off and results in excessive unburned hydrocarbon emissions during the critical initial seconds; the goal is to optimize system response time to achieve faster emission reduction and meet stringent cold-start emission standards.

Solution directions generated for this problem

Problem Direction 1 :

ImproveActuator response speed
VS
ConstraintControl system energy consumption

Inspiration 1 : Cross-domain reference

Application Principle: #19 Periodic action
Cross-domain applicability Assess applicability
Controlling an electrically-driven actuator
Innovative Solution Refine solution

Pulse-width modulated valve actuation with capacitor energy buffering

PWM-driven valve with capacitor buffer for fast response without battery stress
How to solve :
  • Install supercapacitor bank (10-20F, 16V rated) charged slowly during cranking at 0.5-1A constant current, decoupled from battery transient load
  • Drive solenoid valve with high-frequency PWM (20-50kHz, 80% duty cycle) using capacitor discharge — deliver 15-25A peak current in 0.3-0.5s actuation window
  • Implement closed-loop position feedback with Hall-effect sensor (±0.1mm resolution) to terminate PWM pulse precisely when valve reaches full-open position, preventing energy waste
Expected Effect : Actuation time ≤0.5s; battery peak draw <5A; energy efficiency +40% vs continuous drive
Risk Control :
  • capacitor ESR drift over temperature cycles
  • PWM noise coupling to engine control unit
  • valve coil thermal runaway under repeated actuation

Problem Direction 2 :

ImproveAir pathway flow rate
VS
ConstraintPathway manufacturing precision

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Installation for applying glue to fibers for the production of fiberboard
Innovative Solution Refine solution

Segmented dual-lumen secondary air duct with precision-only outlet insert

Split flow path by function
How to solve :
  • Use dual parallel ducts from pump to manifold, each hydraulic dia. 14–16mm, bend radius >2.5D, standard tube Ra≤6.3μm
  • Add a short precision outlet insert only at injector end, 25–40mm long in PPS or PTFE-lined 304SS, outlet Ra≤1.6μm, edge radius 0.3–0.5mm
  • Build by modular joining: blow-molded PA66-GF30 or hydroformed 304SS trunks, laser-weld or clamp assembly, leak test 30kPa for 10s, flow bench accept ≥150% baseline at ΔP=5kPa
Expected Effect : Flow +50 to 70%;system lag cut 0.2 to 0.4s;cat light-off within 3s;cost +8 to 15% vs full-precision duct;trunk tolerance ±0.30mm, insert ±0.05mm
Risk Control :
  • junction leakage at module seams
  • flow imbalance between branches
  • thermal aging near exhaust

Problem Direction 3 :

ImproveSystem response time
VS
ConstraintControl system energy consumption

Inspiration 1 : Cross-domain reference

Application Principle: #10 Preliminary action
Cross-domain applicability Assess applicability
Climate-control system having thermal storage tank
Innovative Solution Refine solution

Vacuum-assisted pre-positioned secondary air injection valve

Pre-position valve using residual manifold vacuum
How to solve :
  • Capture residual manifold vacuum (40-60 kPa below atmospheric) from previous engine shutdown in a 150 mL sealed chamber connected to the secondary air valve diaphragm, holding the valve 70% open
  • Upon cold start signal, a low-power piezoelectric pilot valve (≤5 W, 0.15 s response) releases vacuum to complete valve opening in 0.3 s total actuation time
  • Install a check valve and vacuum reservoir with leak rate ≤2 kPa/hour to maintain pre-positioning for up to 48 hours between engine cycles, ensuring readiness without continuous power draw
Expected Effect : Response time 0.3 s (70% reduction), peak power 5 W (80% reduction), air injection within 0.8 s total
Risk Control :
  • vacuum reservoir leak rate exceeding specification
  • diaphragm fatigue from pre-load stress
  • piezoelectric valve response degradation at low temperature

Problem Direction 4 :

ImproveAir pathway flow rate
VS
ConstraintControl system energy consumption

Inspiration 1 : Cross-domain reference

Application Principle: #2 Taking out
Cross-domain applicability Assess applicability
Pressure and current reducing impeller
Innovative Solution Refine solution

Exhaust pulse-driven passive air injection system

Harness exhaust pressure waves to drive air flow without electrical power
How to solve :
  • Install a venturi ejector nozzle in the exhaust manifold downstream of the exhaust port, utilizing exhaust gas velocity (typically 80-120 m/s during cold start) to entrain ambient air through suction effect
  • Design a reed valve check valve assembly at the air intake port with cracking pressure ≤0.5 kPa and flow area ≥800 mm² to enable passive air induction driven by exhaust pulses, eliminating the need for electric air pump
  • Integrate a pulse accumulator chamber (volume 0.8-1.2 L) between the venturi and catalyst inlet to smooth pulsating flow into steady injection, achieving 50% flow rate increase (from baseline 20 L/min to 30 L/min) with zero electrical power draw
Expected Effect : Flow rate +50%, power consumption -100%, response time <0.8s
Risk Control :
  • exhaust backpressure increase risk
  • reed valve fatigue under thermal cycling
  • venturi nozzle carbon fouling
Patsnap Eureka Solution