Improvements of Exhaust Gas Emissions and Cold Startability of Heavy Duty Diesel Engines by New Injection-Rate-Control Pump

In order to investigate the effects of high injection pressure on engine performance and exhaust emissions, some experimental high injection pressure in-line pumps were made and tested.

Increasing fuel spray momentum by high injection pressure could reduce smoke emission, but excessive increase in injection pressure was found not so effective in further reducing smoke emission.

Accordingly, a high injection pressure should be accomplished within the low engine speed range a feature that has been very difficult to achieve for a conventional in-line pump.

An electronic controlled injection-rate-control pump with a variable prestroke mechanism can provide higher injection pressure in low engine speed range and advances injection timing in high engine speed range. This pump can improve fuel economy in low engine speed range and emissions (smoke and particulate) over transient FTP for HDE's. This pump with prestroke control sleeve directly driven by a solenoid is capable of achieving timing advance without delay even at engine cold starting and hence is effective in improving cold start-ability.