Control system for diesel engine during cold-engine warm-up

• US 6,273,056 B1
• Filed: 12/03/1998
• Issued: 08/14/2001
• Est. Priority Date: 12/15/1997
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Shirakawa, Takashi, Kimura, Shuji
• Primary Examiner(s): Argenbright, Tony M.
• Assistant Examiner(s): Vo, Hieu T.
• Application Number:
  US09/205,092
• Time in Patent Office: 985 Days
• Field of Search: 123/305, 123/306, 123/406.53, 123/406.55, 123/179.5, 123/491, 123/339.1, 123/568.11, 123/568.12, 123/568.21
• US Class Current: 123/305
• CPC Class Codes: F02B 1/12 with compression ignition with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00
• CPC Class Codes: F02B 2275/14 Direct injection into combustion chamber
• CPC Class Codes: F02B 2275/18 DOHC [Double overhead camshaft]
• CPC Class Codes: F02B 29/0406 Layout of the intake air cooling or coolant circuit
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02B 37/24 by using pumps or turbines with adjustable guide vanes
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 21/08 the other gas being the exhaust gas of engine
• CPC Class Codes: F02D 2200/063 Lift of the valve needle
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/0057 Specific combustion modes combustion modes per se F02D41/3017
• CPC Class Codes: F02D 41/0077 Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position EGR valve position sensor F02M26/48
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: F02D 41/068 for warming-up
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02D 41/3076 with special conditions for selecting a mode of combustion, e.g. for starting, for diagnosing
• CPC Class Codes: F02D 41/401 Controlling injection timing F02D41/402 takes precedence
• CPC Class Codes: F02D 41/408 of the distributing type
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/28 with liquid-cooled heat exchangers
• CPC Class Codes: F02M 41/042 : by means of mechanical drive
• CPC Class Codes: F02M 41/126 : valves being mechanically or electrically adjustable sleeves slidably mounted on rotary piston
• CPC Class Codes: F02M 41/128 : Varying injection timing by angular adjustment of the face-cam or the rollers support
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A diesel engine comprises a combustion-temperature control device for adjusting a combustion temperature of the engine depending on an engine operating condition, and an ignition-delay-duration control device for adjusting an ignition delay duration depending on the engine operating condition. An engine-temperature sensor is provided for detecting an engine temperature. During cold-engine warm-up period, an electronic control unit effectively compensates for both the combustion temperature and the ignition delay duration depending on the engine temperature, to reconcile the slow initial combustion in the early combustion stage and the sharp combustion in the middle or later combustion stage and so as to realize a so-called low-temperature premixed combustion with an increased rate of premixed combustion to diffusion combustion under a condition of low combustion temperatures.

Claims

1. A diesel engine comprising:

a sensor for detecting an engine temperature;

a combustion-temperature control device which adjusts a combustion temperature of the engine depending on engine speed, engine load, and the engine temperature detected by the sensor; and

an ignition-delay-duration control device which adjusts an ignition delay duration depending on the engine speed, the engine load, and the engine temperature detected by the sensor, and said ignition delay duration being defined as a time duration between a start of fuel-injection and a start of ignition.

2. The diesel engine as claimed in claim 1, wherein said combustion-temperature control device comprises an exhaust gas recirculation system.

3. The diesel engine as claimed in claim 2, wherein said exhaust gas recirculation system comprises:

an exhaust-gas-recirculation passage interconnecting an intake-air passage and an exhaust-gas passage;

an exhaust-gas-recirculation valve which adjusts an amount of exhaust gases recirculated through the exhaust-gas-recirculation passage; and

a processor programmed to perform the following,

(a) calculating a target exhaust-gas-recirculation valve opening of the exhaust-gas-recirculation valve based on the engine speed and the engine load;

(b) compensating for the target exhaust-gas-recirculation valve opening based on the engine temperature; and

(c) controlling the exhaust-gas-recirculation valve based on the compensated target exhaust-gas-recirculation valve opening.

4. The diesel engine as claimed in claim 3, wherein said processor is further programmed for:

(d) decreasingly compensating for the target exhaust-gas-recirculation valve opening as the engine temperature decreases, when the engine temperature is below a predetermined temperature.

5. The diesel engine as claimed in claim 3, wherein said ignition-delay-duration control device comprises a swirl generating device for generating a controlled swirl flow in a combustion chamber of the engine.

6. The diesel engine as claimed in claim 5, wherein said swirl generating device comprises:

a swirl control valve which adjusts a swirl intensity of the controlled swirl flow generated in the combustion chamber of the engine; and

a processor programmed to perform the following,

(a) calculating an engine-temperature corrected engine speed by compensating for the engine speed by the engine temperature;

(b) calculating an engine-temperature corrected engine load by compensating for the engine load by the engine temperature;

(c) calculating a target swirl-control-valve opening of the swirl control valve based on the engine-temperature corrected engine speed and the engine-temperature corrected engine load; and

(d) controlling the swirl control valve based on the calculated target swirl-control-valve opening.

7. The diesel engine as claimed in claim 6, wherein said processor is further programmed for:

(e) calculating the engine-temperature dependent engine speed by decreasingly compensating for the engine speed as the engine temperature decreases, when the engine temperature is below a predetermined temperature;

(f) calculating the engine-temperature dependent engine load by decreasingly compensating for the engine load as the engine temperature decreases, when the engine temperature is below the predetermined temperature;

(g) calculating the target swirl-control-valve opening that produces a high-level swirl flow, when a condition where the engine-temperature dependent engine sped is below a predetermined engine speed and a condition where the engine-temperature dependent engine load is below a predetermined engine load are simultaneously satisfied; and

(h) calculating the target swirl-control-valve opening that produces a low-level swirl flow, when one of a condition where the engine-temperature dependent engine speed is above the predetermined engine speed and a condition where the engine-temperature dependent engine load is above the predetermined engine load is satisfied.

8. The diesel engine as claimed in claim 1, wherein said ignition-delay-duration control device comprises a fuel-injection timing adjustment device.

9. The diesel engine as claimed in claim 8, which further comprises an electronic fuel-injection system having a fuel injector, and wherein said fuel-injection timing adjustment device comprises a processor programmed to perform the following:

(a) calculating a target fuel-injection timing based on the engine speed and the engine load;

(b) compensating for the target fuel-injection timing based on the engine temperature; and

(c) controlling the fuel injector based on the compensated target fuel-injection timing.

10. The diesel engine as claimed in claim 9, wherein said processor is further programmed for:

(d) compensating for the target fuel-injection timing so that the target fuel-injection timing is advanced as the engine temperature decreases, when the engine temperature is below a predetermined temperature.

11. The diesel engine as claimed in claim 1, which further comprises an exhaust-gas-recirculation gas cooling device which cools part of exhaust gases sent back through the engine.

12. The diesel engine as claimed in claim 1, wherein the sensor comprises a water-temperature sensor which detects a temperature of engine coolant.