7.2. System of simplification of cold start of the diesel engine
General information
For achievement of necessary temperature of ignition of the air-fuel mix compressed in cylinders of the cold engine the system of simplification of cold start is used.
The special candle consisting of the case with the heating core, vpressovanny in it, created by two spirals is rolled in the combustion chamber of each of cylinders: heating and adjusting. After giving of tension the heating spiral in a core heats up within several seconds to temperature of 850 °C, at the same time current, passed through a candle reaches 30 A. S increase in extent of warming up increases and resistance was filched that promotes decrease in current to value 15 - 25 A. After shutdown of a control lamp of system of an incandescence on the dashboard it is possible to carry out start the engine.
Time spent for a preliminary warming up of cylinders makes no more than 12 seconds and is regulated by the special relay and the module of engine management (ECM) obtaining information on the current temperature of cooling liquid of the engine via the ECT sensor. On the basis of the analysis of the obtained data of ECM exercises control of duration of functioning of system of an incandescence and working current of heating.
Principle of functioning of system of preheat
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| Completeness of combustion of working mix is defined by engine turns: Over 500 in a minute — Full combustion Less than 100 in a minute / more than 1-second stop — Incomplete combustion |
Duration of a phase of preheat is determined by temperature of cooling liquid (ECT ® ECM sensor), - the corresponding dependence is presented in the table.
| Temperature of cooling liquid, °C | 130 | 40 | 20 | 0 | - 25 |
| Time of activation of the relay, with | 1 | 7 | 8 | 10 | 12 |
| Time of activation of a control lamp of preheat, with | 1 | 2 | 3 | 4 | 7 |
Compulsory shutdown of a phase of a preliminary incandescence happens at start of the engine after turning of a key in situation START.
In a phase of thermoheat it is used residual warmly heating elements of candles after return of a key from situation START in position of OFF in unsuccessful attempt of start of the engine before end of a phase of preheat when the candle relay is activated.
The system passes into a post-heat phase after successful implementation of start. Dependence of functioning of candles of an incandescence in this phase from temperature of cooling liquid is presented in the table.
| Temperature of cooling liquid, °C | 70 | 60 | 50 | 30 | - 40 |
| Time of activation of the relay, mines | 0 | 1.5 | 4.9 | 8.1 | 8.1 |
Shutdown of post-heat happens at the termination of admissions of ignition of working mix, and also on reaching temperature of cooling liquid of value in 70 °C. Besides, management of functioning of a phase of post-heat is made on turns of the engine and extent of squeezing of the accelerator pedal.
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Parameters of activation of a phase of post-heat depending on engine turns. |
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Parameters of activation of a phase of post-heat depending on extent of squeezing of the accelerator pedal. |
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Temperature drop of cooling liquid gives values of 60 °C to repeated activation of post-heat below. |
Protective shutdown of the relay of candles of an incandescence happens at excess by value battery tension in 16 V when the engine is not turned.
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When lowering voltage below 14 V more than for two seconds of the relay it is activated again. Besides, shutdown of candles is made at failure actually of the relay, and also ECT, CMP sensors and position of the accelerator pedal. |