JP2004044551A - Warming-up assisting system for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for assisting warming-up a diesel engine by actively controlling a heat recovery system with cooling water, which is constituted of cooling parts attached onto the engine. <P>SOLUTION: This warming-up assisting system for the diesel engine comprises a heater for heating a vehicle inside with circulating engine cooling water serving as a heat source; a cooling mechanism (for example, a fuel cooler) 26 which is provided concomitantly with an engine and conducts heat exchange to the engine cooling water; and a control means 30 for increasing heat exchange rate in the cooling mechanism. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a system for assisting warm-up of a diesel engine.
[0002]
[Prior art]
From the viewpoint of fuel economy, the application range of diesel engines is expanding. That is, in a diesel engine, fuel is burned under a high compression ratio and a large excess air ratio, so that its thermal efficiency is much higher than that of a gasoline engine.
[0003]
In recent years, a common rail fuel injection system has been developed as a fuel supply device for a diesel engine. This common rail fuel injection system stores high-pressure fuel generated by a supply pump in a common rail, and injects high-pressure fuel from the common rail to each cylinder of the engine via each injector. The pressure, that is, the injection pressure is configured to be able to be controlled irrespective of the engine speed (for example, see JP-A-2000-248983).
[0004]
[Problems to be solved by the invention]
By the way, high thermal efficiency of the engine means, in other words, that the amount of heat supplied to the engine cooling water as a heat loss is small. Therefore, in a vehicle equipped with a diesel engine, there is a problem in that the warming-up performance in a cold state is insufficient, such as in the morning in winter, and the temperature rise in the vehicle interior is delayed.
[0005]
The present invention has been made in view of the above-described problems, and an object of the present invention is to actively control a heat recovery system using cooling water, which is configured by a cooling component attached to the engine, to thereby achieve a diesel engine. It is to constitute a system for assisting warm-up.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, there is provided a system for assisting warm-up of a diesel engine, comprising a heater for heating the interior of a vehicle using circulating engine cooling water as a heat source, A cooling mechanism for performing heat exchange with the engine cooling water, and control means for increasing the heat exchange amount in the cooling mechanism when the temperature in the vehicle is lower than a predetermined reference value. A warming assist system for a diesel engine is provided.
[0007]
According to a second aspect of the present invention, the diesel engine employs a common rail fuel injection system, the cooling mechanism is a fuel cooler that cools fuel, and the control unit includes an engine. By increasing the rotation speed and / or the fuel pressure in the common rail, the amount of heat of the fuel is increased, and as a result, the amount of heat exchange between the fuel and the engine cooling water in the fuel cooler is increased.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0009]
FIG. 1 is an overall configuration diagram showing one embodiment of a diesel engine warm-up assist system according to the present invention. This diesel engine employs a common rail fuel injection system. The supply pump 10 connected to and driven by the output shaft of the diesel engine sucks the fuel stored in the fuel tank 12 through the supply pipe 14, and pressurizes and discharges this as high-pressure fuel.
[0010]
The high-pressure fuel pressurized and discharged by the supply pump 10 is stored via a supply pipe 16 in a common rail 18 which is a pressure accumulation pipe. Then, the high-pressure fuel stored in the common rail 18 is supplied to the injector 22 via the supply pipe 20, and is injected from the injector 22 into a corresponding cylinder of the diesel engine.
[0011]
In this embodiment, a four-cylinder diesel engine is assumed, and fuel is injected and supplied for each cylinder by an injector 22 provided for each cylinder. Excess fuel not injected from the injector 22 is returned to the fuel tank 12 via the return pipe 24.
[0012]
The supply pump 10 has a suction port 10a connected to the supply pipe 14, a discharge port 10b connected to the supply pipe 16, and a return port 10c connected to the return pipe 24, and controls the fuel discharge amount. Things. Excess fuel not discharged from the discharge port 10b is returned to the fuel tank 12 via the return port 10c and the return pipe 24.
[0013]
Further, the common rail 18 in which high-pressure fuel is stored has four output ports 18a to 18d corresponding to each cylinder of the diesel engine, and has a pressure regulator 18e. The fuel is returned to the fuel tank 12 via the pressure regulator 18e and the return pipe 24.
[0014]
A fuel cooler 26, which is a heat exchanger for cooling the fuel by causing heat exchange between the engine coolant and the fuel circulating in the engine, is provided in the middle of the return pipe 24. Further, a heater 28 for heating the inside of the vehicle using the engine cooling water heated by the fuel cooler 26 as a heat source is provided.
[0015]
An electronic control unit (hereinafter, referred to as an ECU) 30 determines an optimal fuel injection timing and an optimal fuel injection amount in accordance with an engine state such as an engine speed, a crank angle position, an accelerator opening, and controls an electromagnetic valve in the injector. Thus, the fuel in the common rail 18 is injected into each cylinder of the diesel engine.
[0016]
Further, the common rail 18 is provided with a common rail pressure sensor 32 for detecting the pressure of the fuel in the common rail. The ECU 30 controls the supply pump 10 so that the fuel pressure in the common rail becomes an optimum value set according to the accelerator opening and the like. To control the amount of pumping.
[0017]
By the way, as described above, a diesel engine has a high thermal efficiency and a small amount of heat supplied to the engine cooling water due to heat loss. There is a problem that is delayed.
[0018]
Therefore, in the present embodiment, when it is necessary to raise the temperature in the passenger compartment during cold time, the engine speed and / or the fuel pressure in the common rail are controlled, and the supply pump 10 is required to perform combustion in the engine. The amount of heat of the fuel, which is increased by the amount of heat, is transmitted to the heater 28 through the fuel cooler 26 to warm the air in the vehicle compartment.
[0019]
A processing procedure of a control routine executed by the ECU 30 to realize such control is shown in a flowchart of FIG. First, at step 102, an ignition switch (IG SW) is turned on, and control according to this routine is started.
[0020]
Next, in step 104, vehicle interior temperature T whether a predetermined reference value above T ₁ is determined. The vehicle interior temperature T may be detected by a temperature sensor provided in the vehicle interior, or may be substituted by the engine coolant temperature.
[0021]
When T ₁ ≦ T, that is, when it is determined that the vehicle is not in the cold state, the operation proceeds to the normal operation mode. On the other hand, when T <T ₁ , that is, when it is determined that the vehicle is in the cold state, the process proceeds to step 106. .
[0022]
In step 106, it is determined whether or not the vehicle is currently idling. In the present embodiment, when the accelerator pedal operation amount of the driver is zero (the state in which the driver does not depress the accelerator pedal), it is determined that the engine is currently idling. If it is determined in step 106 that the vehicle is currently idling, the process proceeds to step 108. If it is determined that the vehicle is not currently idling, the process proceeds to step 110.
[0023]
In step 108, the idle speed and the fuel pressure in the common rail are increased (increased) by a fixed rate as compared with the normal operation state. On the other hand, in step 110, since the idle operation is not being performed, only the fuel pressure in the common rail is increased by a certain rate as compared with the normal operation state. These up rates can be, for example, 20%.
[0024]
In either of the steps 108 and 110, the fuel temperature is increased, the fuel cooler 26 heats the engine cooling water with the fuel, and the heater 28 heats the vehicle interior air with the engine cooling water. And warming up of the engine and air is promoted.
[0025]
In step 112 it is performed subsequent to step 108 or 110, vehicle interior temperature T whether a predetermined reference value T ₀ or more is determined. When T ₀ ≦ T, that is, when it is determined that the warm-up has been achieved, the operation shifts to the normal operation mode. On the other hand, when T <T ₀ , that is, when it is determined that the warm-up is still insufficient, step 106 is performed. Return to
[0026]
FIG. 3 is a characteristic diagram for explaining the effect when the present invention is implemented. The horizontal axis indicates the engine speed, and the vertical axis indicates the amount of generated heat. Note that the amount of generated heat is proportional to the fuel temperature.
[0027]
In FIG. 3, the solid line shows the normal characteristics when the present invention is not implemented, while the broken line shows the characteristics when the present invention is implemented. Normally, the amount of heat shown by the solid line is released into the fuel, and the fuel temperature rises. On the other hand, when the present invention is applied, the amount of generated heat increases as shown by a broken line. That is, the amount of heat ΔQ between the broken line and the solid line is used for warming up.
[0028]
The embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments, and various embodiments can be adopted. For example, in the present embodiment, a fuel cooler is used as a cooling mechanism for performing heat exchange with engine cooling water, but an EGR cooler, an oil cooler, or the like may be used instead.
[0029]
An EGR cooler, an oil cooler, and the like are also a heat recovery system using cooling water provided in association with the engine. Whereas these conventional systems depend on a passive heat recovery system, that is, the amount of heat discharged from the engine side, when the present invention is applied, an active heat recovery system, that is, a control (from the ECU) is used. Command), it becomes a system capable of recovering the necessary amount of heat.
[0030]
【The invention's effect】
As described above, according to the present invention, a system for assisting warm-up of a diesel engine is configured by actively controlling a heat recovery system using cooling water attached to an engine. Even the cabin temperature rises early.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing one embodiment of a diesel engine warm-up assist system according to the present invention.
FIG. 2 is a flowchart showing a processing procedure of a control routine executed by an electronic control unit (ECU).
FIG. 3 is a characteristic diagram for explaining an effect when the present invention is implemented.
[Explanation of symbols]
Reference Signs List 10 supply pump 10a suction port 10b discharge port 10c return port 12 fuel tank 14 supply pipe 16 supply pipe 18 common rail 18a to 18d output port 18e pressure regulator 20 supply pipe 22 injector 24 Return piping 26 Fuel cooler 28 Heater core 30 Electronic control unit (ECU)
32 ... Common rail pressure sensor

Claims (2)

A system that assists in warming up a diesel engine,
A heater for heating the interior of the vehicle using the circulating engine cooling water as a heat source,
A cooling mechanism that is provided along with the engine and performs heat exchange with engine cooling water;
Control means for increasing the amount of heat exchange in the cooling mechanism when the temperature in the vehicle is lower than a predetermined reference value;
A warm-up assist system for a diesel engine, comprising: The diesel engine employs a common rail fuel injection system, the cooling mechanism is a fuel cooler for cooling fuel, and the control means increases an engine speed and / or a fuel pressure in the common rail. 2. The diesel engine warm-up assist system according to claim 1, wherein the amount of heat of the fuel is increased, and as a result, the amount of heat exchange between the fuel and the engine cooling water in the fuel cooler is increased.

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