RU2797813C1 - Method for warming up an internal combustion engine at idle - Google Patents

Abstract

FIELD: engine building.

SUBSTANCE: method for warming up an internal combustion engine at idle includes, after starting the engine, changing the ignition advance angle, fuel injection and ignition of the combustible mixture in accordance with this angle. When the engine is started, the piston (2) moves down, sucking air into the cylinder (1). After it passes bottom dead centre, the intake valve closes and the suction stroke ends. During the cycle of operation, fuel is injected at least once by the nozzle (5) into the combustion chamber (4) of the fuel, forming a combustible mixture (6). The ignition advance angle is changed upwards and the combustible mixture is ignited in accordance with the last at the moment the suction stroke is completed. During the combustion of the mixture, heat is transferred from the combustion products through the walls of the cylinder (1) and the combustion chamber (4) of the coolant (7).

EFFECT: reduction of warm-up time of the engine at idle.

6 cl, 2 dwg

Description

The invention relates to engine building and can be used in internal combustion engines.

The prototype is a method of warming up an internal combustion engine, including the ignition of the combustible mixture, reducing after starting the engine ignition timing for the time of warming up the engine and restoring it to its original value before the end of the warm-up [US Pat. RF 2101549, IPC F02P, 5/02, 1998].

The disadvantages of the prototype is the insignificant heating efficiency compared to the conventional method (without changing the ignition timing), since later ignition will lead to incomplete combustion of the mixture and losses, in connection with this, released during combustion of heat.

The objective of the invention is to eliminate these disadvantages, namely, to reduce the warm-up time of the engine at idle and improve the performance of the engine.

The problem is solved by the fact that in the method of warming up an internal combustion engine at idle, which includes, after starting the engine, changing the ignition timing, fuel injection and ignition of the combustible mixture in accordance with this angle, injection is performed at least once during the operation cycle, while the ignition advance angle is changed upwards and the combustible mixture is ignited in accordance with the latter at the moment the suction stroke is completed.

By means of injection, a combustible mixture of stoichiometric composition is formed. By means of injection, a combustible mixture and a lean composition are formed. By means of injection, a combustible mixture and an enriched composition are formed. The second time injection and ignition is carried out at the initial value of the ignition advance angle. As the engine warms up through injection, a combustible mixture is formed that differs from the stoichiometric composition.

These distinctive features allow you to achieve the following advantages compared to the prototype.

Performing at least one injection during a cycle of operation, and at the same time changing the ignition timing in the direction of increasing the ignition timing and carrying out, in accordance with the last ignition of the combustible mixture at the moment of completion of the suction stroke, allows the mixture to be burned on the compression stroke. As a result, the heat of combustion products is efficiently transferred through the walls of the coolant cylinder. It should be noted that, firstly, heat transfer is carried out by both radiation and convection, and with the turbulent movement of the burning mixture, the heat transfer coefficient by convection increases. Secondly, there is a margin of time for the combustion of the mixture in comparison with the time of its combustion in the combustion chamber, which contributes to its more complete combustion, as well as the possibility of burning a larger amount of the mixture. All this increases the specific heat release per unit of combustion surface. Thirdly, the compression of the combustion products contributes to an additional increase in their temperature, as a result of which their temperature in the combustion chamber (when the piston passes the TDC) will be higher than the temperature of the combustible mixture in the combustion chamber in the usual way, when the cold mixture is first compressed, and then its burning. All this reduces the warm-up time of the engine.

Formation by injection of a combustible mixture of stoichiometric composition is expedient to be carried out after starting the engine at low temperatures, when the concentration limits of ignition are narrowed. In this case, ignition should occur even at the narrowest specified limits.

The formation of a combustible mixture and a lean composition by means of injection makes it possible to save the oxidizer and use it to form a combustible mixture during the second injection of fuel, in which the resulting mixture is ignited already in accordance with the initial ignition timing.

The formation of a combustible mixture and an enriched composition by means of injection increases the specific heat release per unit of the combustion surface, which reduces the warm-up time. In this case, the working stroke must be organized at the expense of other engine cylinders.

The implementation of the second injection and ignition at the initial value of the ignition timing allows you to further increase the temperature of the combustion products. In addition, having a sufficiently high temperature, the oxidizer remaining after the first ignition makes it possible to expand the concentration limits of ignition and, therefore, makes it possible to form either a leaner or richer combustible mixture in the combustion chamber, as well as organize a working stroke during the second injection.

The formation of a combustible mixture that differs from the stoichiometric composition as the engine warms up by means of injection allows you to control the amount of heat released during combustion, for example, as the temperature rises, the load on the engine will drop, so the stroke power can be reduced by burning less fuel the second time, and the first time burn a richer mixture to increase heat dissipation. All this improves performance.

The invention is illustrated by drawings.

In FIG. 1 shows a cylinder diagram of an internal combustion engine at the end of the suction stroke. In FIG. 2 shows a diagram of the cylinder of an internal combustion engine at the moment the piston approaches TDC.

The internal combustion engine contains a combustion chamber 4 formed by a piston 2 placed in the cylinder 1 and walls 3, in which a nozzle 5 is installed for spraying fuel 6 into the cylinder and the combustion chamber, which are washed by the coolant 7.

The internal combustion engine works as follows.

After starting a cold engine, piston 2 begins to move down, while sucking air (oxidizer) into cylinder 1. After it passes BDC, the intake valve closes and the suction stroke ends. After that (or in the process of suction), fuel is injected into cylinder 1 and combustion chamber 4 by nozzle 5, forming, for example, an enriched mixture 6, which, for example, is ignited by a spark of a candle (not shown) (Fig. 1). During the combustion of this enriched fuel mixture, heat is transferred from the combustion products through the walls of the cylinder 1 and the combustion chamber 4 of the coolant 7.

Heat transfer from combustion products to the wall surface occurs both by radiation and convection, which increases the specific heat release per unit of the combustion surface, while the surface through which heat transfer occurs is significantly larger than the surface of the combustion chamber, the walls of which are affected by radiation when the fuel mixture is burned in the usual way , for example, as in the prototype. In addition, there is a margin for the combustion time of the fuel mixture in the cylinder compared to combustion in the combustion chamber in the usual way, which, firstly, makes it possible to enrich the mixture as much as possible, and secondly, the duration of the heat transfer process from the combustion products to the indicated walls increases. .

Piston 2 continues to move upward due to the inertia forces of the crankshaft flywheel and the work done during the stroke of the other cylinder. In this case, compression and turbulent motion of the burning mixture occur, resulting in an increase in the heat transfer coefficient by convection and an increase in its temperature (Fig. 2). All this increases the amount of heat transferred to the coolant. As a result, on the one hand, the temperature of the combustion products increases due to compression, and on the other hand, it decreases due to heat transfer by radiation and convection. When the piston passes the TDC, the combustion products are compressed as much as possible, after which they begin to expand as the piston 2 moves down, also giving off heat to the coolant.

To warm up other cylinders of the engine, the described process must be performed in turn in all cylinders of the internal combustion engine.

It is also possible to combine the heating of the cylinder by the proposed method with the stroke of the piston of this cylinder. To do this, after starting a cold engine into cylinder 1, sucking in air and ending the intake stroke with injector 5, fuel is injected into cylinder 1 and combustion chamber 4, forming a lean fuel mixture, which is also ignited. When the burning mixture is compressed, the described heat transfer process occurs, however, the heat release is less due to the combustion of a lean mixture with a lower fuel content. When the piston approaches the position corresponding to the initial ignition timing, the nozzle 5 injects a portion of fuel in an amount that can react with the oxygen remaining in the combustion products. Since the combustion products still have a sufficiently high temperature, as well as the volumes of the burning mixture, the injected fuel (like diesel) will begin to ignite, i.e. spark ignition may not be necessary. Note that when this mixture is ignited (second injection), the lower concentration limit of ignition should change slightly, since the combustion products, which are essentially an inert additive, replace part of the oxygen that was present in a lean mixture (first injection) in a large excess and also essentially an inert additive. However, a change in temperature affects the lower and upper concentration limits, which expand with increasing temperature of the mixture. The fuel burned after the second injection increases the temperature and the amount of combustion products, as well as their pressure. As a result, a working stroke is organized, although of a lower power than it could be if the entire fuel charge was burned in the chamber at once, i.e. total fuel used for the first and second time. Such an organization of the working stroke allows simultaneous heating of all engine cylinders.

However, it is not always possible to form a rich or lean fuel mixture for the first time. At very low temperatures, the concentration boundaries narrow, so initially, under such conditions, it is necessary to inject fuel, the amount of which will form a combustible mixture with a composition close to stoichiometric. If we take into account that at low temperatures the fuel evaporates more slowly, then it is possible to carry out technical ignition a little earlier than the end of the suction stroke in order to ensure a longer contact time of the combustion products with the cylinder walls. As the engine warms up, the composition of the mixture can be made different from stoichiometric.

Note that the rapid warming up of the engine will also contribute to the rapid heating of the stove of the vehicle interior.

The implementation of the invention will reduce the duration of engine warm-up at idle and the heating time of the vehicle stove practically without altering existing modern internal combustion engines.

Claims (6)

1. A method for warming up an internal combustion engine at idle, including, after starting the engine, changing the ignition timing, fuel injection and ignition of the combustible mixture in accordance with this angle, characterized in that injection is performed at least once during the operation cycle, while changing in the direction of increasing the ignition timing and produce in accordance with the last ignition of the combustible mixture at the end of the suction stroke. 2. The method according to claim 1, characterized in that a combustible mixture of stoichiometric composition is formed by injection. 3. The method according to p. 1, characterized in that by means of injection a combustible mixture is formed and a lean composition. 4. The method according to p. 1, characterized in that by means of injection a combustible mixture and an enriched composition are formed. 5. The method according to p. 1, characterized in that the second time the injection and ignition is carried out at the initial value of the ignition timing. 6. The method according to any one of paragraphs. 1, 2, characterized in that as the engine warms up through injection, a combustible mixture is formed that differs from the stoichiometric composition.

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