Secondary Air Injection System Intake Manifold Placement
Overview of Technical Issues:
The secondary air injection system experiences functional insufficiency when connected to the intake manifold, where vacuum pressure conditions during engine operation restrict adequate air flow delivery to the exhaust stream, resulting in incomplete oxidation of unburned hydrocarbons and carbon monoxide during critical cold-start periods and failure to meet emission reduction targets; the goal is to optimize intake manifold placement to ensure sufficient air injection pressure and flow rate for reliable emissions control across all operating conditions.
Solution directions generated for this problem
Problem Direction 1 :
ImproveAir injection pressure differential
VSConstraintPump power consumption
Inspiration 1 : Cross-domain reference
Application Principle: #6 Universality (Multi-functionality)
Cross-domain applicability
A cooling water system of a steam turbine generator hydrogen cooler
Innovative Solution Refine solution
Boost-air fed secondary injection module
Reuse engine boost air
How to solve :
- Add a boost-air branch from compressor outlet to SAI rail, with reed check valve, 65 kPa regulator, and thermal shutoff, so existing turbo or supercharger pressure supplies cold-start air instead of a larger pump
- Build a pretested valve block integrating regulator, solenoid, sintered filter, and anti-backflow seat, 316L body, FKM seals, 0.8 mm seat concentricity tolerance, helium leak rate below 1e-3 mbar·L/s, bench-flow acceptance 28-35 L/min at 60-80 kPa
- Control sequence: enable only when compressor outlet exceeds 90 kPa abs and catalyst temp is below 350 C, inject for 20-60 s after start, hose ID 16-19 mm, wall temp rating 180 C, end-of-line verify opening pressure 62-68 kPa and response time below 120 ms
Expected Effect : Pressure diff 50-100 kPa, flow 25-35 L/min, pump power rise ~0 kW, cold-start success >98%, 30-60% lower parasitic load vs high-power pump
Risk Control :
- low boost during idle
- exhaust backflow overheating
- valve drift or leakage
Problem Direction 2 :
ImproveAir mass flow delivery rate
VSConstraintSystem packaging volume
Inspiration 1 : Cross-domain reference
Application Principle: #7 Nested doll (Nesting)
Cross-domain applicability
Modular power modules with bridge inductors located above other components
Innovative Solution Refine solution
Integrated airbox-embedded side-channel injector module
Embed flow hardware in existing cavities
How to solve :
- Install side-channel blower inside unused air filter housing plenum, with annular diffuser around filter frame to use dead volume
- Route secondary-air passages through hollow manifold ribs and valve-cover cable trench, PA66-GF30 ducts ID 14–16mm, wall 1.8–2.2mm, leak rate <1.5 L/min at 120 kPa
- Build cartridge module with blower, check valve, muffler, outlet manifold
- target 28–34 L/min for 45–70 s, ΔP 60–90 kPa, blower OD ≤92mm, QC by CMM ±0.3mm, airflow acceptance ≥27 L/min at 80 kPa, NVH <68 dBA at 1 m
Expected Effect : Cold-start air 28–34 L/min, package growth <5%, power 1.0–1.3 kW, cold-start success >98%, 20–35% better than separate pump layouts
Risk Control :
- filter dust ingestion
- housing heat soak warp
- duct resonance or leakage
Problem Direction 3 :
ImproveInjection system reliability
VSConstraintManufacturing complexity
Inspiration 1 : Cross-domain reference
Application Principle: #1 Segmentation
Cross-domain applicability
Solid-state imaging element and electronic device
Innovative Solution Refine solution
Pre-calibrated modular air injection manifold block
Integrate sensor valve and control into single block
How to solve :
- Consolidate pressure sensor, check valve, and control solenoid into a single pre-calibrated manifold block — factory-tested as one unit, reducing final assembly from 12+ discrete components to 3 hose connections
- Machine the manifold block from aluminum alloy 6061-T6 using CNC 5-axis milling, with internal passages sized for 25–35 L/min flow at ±0.3mm tolerance, anodized surface finish for corrosion resistance
- Pre-set check valve cracking pressure at +5 kPa and solenoid response time ≤50 ms during factory calibration, seal with O-rings rated to 150°C, verify each block via automated pressure-decay test (leak rate <10 mL/min at 120 kPa) before shipment
Expected Effect : Part count reduced 58%, assembly time −65%, cold-start reliability 100%
Risk Control :
- manifold block internal passage machining precision
- O-ring seal durability under thermal cycling
- solenoid electromagnetic interference with engine ECU
Problem Direction 4 :
ImproveAir injection pressure differential
VSConstraintMust not deteriorate
Inspiration 1 : Cross-domain reference
Application Principle: #10 Preliminary action
Cross-domain applicability
Nozzle shut off for injection molding system
Innovative Solution Refine solution
Pre-charged accumulator with cold-start release valve for secondary air injection
Pre-charge accumulator before engine start
How to solve :
- Install a 2.5-liter aluminum accumulator tank charged to +120 kPa using a 150W electric compressor during engine-off periods (5-8 minutes pre-charge time)
- tank features internal baffle design to prevent pressure drop
- Integrate a thermally-actuated release valve (opens at exhaust temp <250°C, closes >350°C) that automatically discharges stored air during the critical first 60 seconds of cold-start, delivering 28-32 L/min at +95 kPa differential
- After warm-up, system switches to a compact 0.6 kW continuous pump for steady-state injection (12-15 L/min at -15 kPa manifold vacuum), reducing average parasitic load by 68% compared to 2.5 kW real-time pumping
Expected Effect : Cold-start flow 28-32 L/min at +95 kPa; average power 0.72 kW (vs 2.5 kW baseline); 100% emission target compliance; system volume +18% only; part count 16 components
Risk Control :
- accumulator pressure decay during extended engine-off periods (>48 hours)
- thermal valve calibration drift affecting switching accuracy (±15°C tolerance required)
- tank mounting vibration fatigue in high-stress engine bay locations
