JPS59229059A - Glow control device of diesel engine - Google Patents

Abstract

PURPOSE:To control a glow heater accurately by a photosensor and a light conductive substance, to conduct light emission from glow heater owing to glow current supply, in the glow plug, and by controlling the state of current application to the glow heater in accordance with the output of said photosensor. CONSTITUTION:This system is composed of an optical fiber 14 of quartz glass, which transmits the glow light emission owing to glow heating and the combustion light in the combustion chamber 10A, a photosensor 16 to sense them, a current supply signaling line 18, and an electronic control unit 20. A glow light emission lead-in part 30B consisting of at least one prism-shaped notch is formed at the periphery of the tip of optical fiber 30. Accordingly both the combustion light and glow light emission are led in the core 30C of this optical fiber 30, which provides possibility not only of glow heating at the starting time of the engine but also of sensing the glow temp. owing to glow light emission as well as the ignition timing using the combustion light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glow control device for a diesel engine, and more particularly to a glow heater disposed within an engine combustion chamber, and a method for maintaining the glow heater in a state where the inside of the fuel gas is cut off from outside air. The present invention relates to an improvement in a glow control device for a diesel engine, which has a glow plug including a cylindrical housing and controls the energization state of the glow heater in accordance with the heat generation temperature of the glow heater.

Generally, when starting a diesel engine, it is necessary to raise the temperature of the compressed air to enable self-ignition. For this reason, for example, a glow heater is placed inside the engine combustion chamber, and a glow heater is installed inside the combustion chamber to keep the combustion chamber from outside air. A glow plug including a cylindrical housing that holds the glow heater in a cut-off state is inserted into an engine combustion chamber, and the glow heater is energized when the engine is started, thereby facilitating the starting of a diesel engine. There is. In order to efficiently heat the glow heater without burning it out and to enable quick engine starting, it is necessary to control the energization state of the glow heater according to the heat generation temperature (hereinafter referred to as glow temperature) of the glow heater. can be,
For this purpose, conventionally, for example, a glow current detection resistor (hereinafter referred to as glow heater series resistance) is connected in series with the glow heater, and the glow temperature is detected from the current flowing through the glow heater series resistance. The energization state of the glow heater is controlled accordingly.

However, with such a method, although the average temperature of the glow heater can be detected, a local overheating state cannot be detected, and breakage of the glow heater may not be prevented. Furthermore, due to the temperature characteristics of the glow heater series resistance, it is not possible to accurately detect the glow heater temperature, and there is a possibility that a temperature different from the actual glow heater temperature may be detected.

Furthermore, the output signal, ie, the voltage across the glow heater series resistor, is small and susceptible to noise. In addition, there is a power loss in the glow heater series resistance, and on the other hand, if the resistance value of the glow heater series resistance is reduced in order to reduce this power loss, there is a problem of heat generation, and there are problems such as poor flexibility in circuit configuration. Was.

Invention A was made to solve the above-mentioned conventional problems, and the temperature of the glow heater can be detected accurately and with good response without using a glow heater series resistor. An object of the present invention is to provide a glow control device for a diesel engine that can accurately control the energization state of a glow heater.

The present invention has a glow plug that includes a glow heater disposed within an engine combustion chamber and a cylindrical housing that holds the glow heater in a state where a combustion guide is cut off from outside air, and the glow plug is configured to respond to the heat generation temperature of the glow heater. A glow control device for a diesel engine for controlling the energization state of a diesel engine includes a light guide disposed in the glow plug for checking the light emission of the glow heater due to glow energization, and a glow light emitted by the light guide. The above object is achieved by providing a photodetector for detecting the glow temperature and controlling the energization state of the glow heater according to the degree of glow temperature detected from the output of the photodetector.

In the present invention, a light guide is provided in the glow plug to guide the light emitted from the glow heater by glow energization, and the glow light emitted by the light guide is detected by a photodetector, and the glow is detected from the output of the photodetector. Since the temperature is detected, combined with the fact that the temperature characteristic of the light guide is small, the heat generation temperature of the glow plug can be detected accurately and with good responsiveness. Therefore, the glow energization state can be controlled with high precision, and the heat generation temperature of the glow heater can be controlled to be constant with narrow turns, thereby improving engine startability.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In this embodiment, as shown in FIG.
The cylinder head 1 of a diesel engine 10 performs glow heating at the time of starting the engine, and detects the glow emission caused by the glow heating and the combustion light in the combustion chamber 10A.
A glow plug 12 inserted and fixed into the 0B, an optical fiber 14 made of quartz glass, for example, for transmitting the light detected by the glow plug 12, and a light transmitted by the optical fiber 14 is detected. A photodetector 16 made of, for example, a silicon photodiode for converting electricity (M), a signal line 18 for supplying electricity to the glow heater built in the glow plug 12, and the photodetector 16.
The output is processed to detect the glow temperature (before engine start) or ignition timing (after engine start), and depending on the detected glow temperature or ignition timing, the energization state of the glow heater or the fuel F4 @ ignition timing is determined. The electronic control unit that controls the
(hereinafter referred to as ECU) 20. Reference numeral 22 in FIG. 1 is a fuel injection nozzle.

The glow plug 12 includes a light guide, for example, an optical fiber 30 made of quartz glass, which is arranged so that its tip 30A faces into the engine combustion IWI OA, as shown in detail in Figure @2.
, a glow heater 32 wound around the tip of the optical fiber 3o, and a metal plate that also serves as one electrode of the glow heater 32, which holds the optical fiber 30 in a state where the inside of the combustion 11A is cut off from the outside air. , a cylindrical housing 34 , 36 made of, for example, stainless steel, a filler 38 of, for example, alumina, filled around the glow heater 32 , which protects the optical fiber 30 and protects the glow heater 3 .
a thermosetting resin 42 for enclosing the rear end of the cylindrical housing 36 and fixing the rear end of the cylindrical electrode 40 in a predetermined position; have. In FIG. 2, 36A is a mounting screw portion for screwing and fixing the glow plug 12 into the cylinder head IOB.

As shown in FIG. 3, a glow emission introducing section 30B consisting of at least one prismatic notch is formed around the tip of the optical fiber 30. As shown in FIG.

Therefore, as shown in FIG. 4, both the combustion light and the glow emission are introduced into the core 30G of the optical fiber 30 and transmitted. It is possible to detect both the glow temperature by light emission and the ignition timing by combustion light. In FIG. 4, 30D is a cladding.

As shown in detail in FIG. 5, the glow control circuit within the ECU 20 directly outputs the output of the battery 50 to the glow heater 932 when, for example, a glow contact Ig provided on the engine switch is turned on before starting the engine. After the engine is started, the output of the battery 50 is normally applied to the glow heater 32 via a glow plug main relay 52 for energizing and performing so-called rapid heating, and a glow plug resistor 54 for protecting the glow heater to perform so-called afterglow. When the glow contact IQ is on, a voltage is applied to the output of the photodetector 16 through the resistor 58.60, that is, a voltage corresponding to the amount of glow emission. and the set voltage v tem corresponding to the control target temperature of the glow heater 32 set in advance.
Comparing p, Glo-1 temperature is better! ! `Il, which outputs ON No. 18 when it is judged to be lower than the target temperature, and a hysteresis-equipped] comparator 62, and a water temperature sensor 64 whose resistor changes depending on the engine cooling water temperature, for example, A main timer 66 outputs an ON signal for a set time that becomes longer as the engine cooling water temperature detected by the water temperature sensor 64 is lower, and a logical product of the outputs of the main timer 66 and the comparator 62 is negated. A NAND circuit 68 to output, a main switching transistor 72 for turning on and off the glow plug main relay 52 according to the output of the NAND circuit 68 input via a resistor 70, and one terminal of a voltage regulator (not shown). output and the water temperature sensor 6
According to the output of 4, when the output of the above terminal is on,
That is, after the engine is started, the sub-timer 74 outputs an ON signal for a set time that becomes longer as the engine cooling water temperature decreases, depending on the output of the water temperature sensor 64.
and a sub-switching transistor 76 that turns on and off the glow plug sub-relay 56 in accordance with the output of the sub-timer 74.

The action will be explained below.

First, in order to start the diesel engine 10, when the glow contact 41o of the engine switch is turned on, the EC
The glow plug main relay 52 of the LJ 20 is turned on, and a large current flows directly from the battery 50 to the glow heater 32, causing it to heat up rapidly. Through this rapid heating,
The heat generation temperature of the glow heater 32 is the upper limit of the set target temperature,
For example, when the temperature reaches 850° C., the output of the inverter 62 is turned off, the main switching transistor 72 is turned off, the glow plug main relay 52 is turned off, and the supply of large current to the glow heater 32 is stopped. The heat generation temperature of the glow heater 32 detected by the output of the photodetector 16 is the lower limit of the set day a temperature, for example 750.
℃, the output of the inverter 62 is turned on again, the main switching transistor 72 is turned on, the glow plug main relay 52 is turned on, and again,
Rapid heating is performed using a large current. This control of the large glow current by turning on and off the glow plug main relay 52 is performed until the output of the main timer 66 is turned off.

Next, when you set the engine switch to the start position and start cranking, the previous state will be reset.
Also, rapid heating is performed using a large current, and this state continues until the engine is started.

When the engine starts, the glow plug main relay 52 is turned off, and only a small current is supplied to the glow heater 32 via the glow plug sub-relay 56 and the glow plug resistor 54, so that so-called afterglow occurs.

This after-glow energization is performed only while the output of the sub-timer 74 is on.

When the engine combustion state is stabilized after the afterglow ends, the ignition timing is detected according to the output of the photodetector 16, and feedback control of the fuel injection timing is performed according to the detected ignition timing.

FIG. 6 shows an example of how the glow heater humidity changes after the glow contact of the engine switch is turned on in iJ3 in this embodiment.

In this embodiment, since the ignition timing sensor and the glow emission sensor are integrated, there is no need to insert many sensors into the seedlings to be burned by the engine, and the structure is relatively simple. That is, in general, when the glow is energized before starting the engine, the engine has not started, and feedback control of the ignition timing is naturally unnecessary. Therefore, as in this embodiment, the ignition timing sensor and the glow emission sensor are integrated. There is no problem even if it is changed. If there is a possibility that the range of glow energization and ignition timing feedback control may be compromised, for example, the ignition timing may be detected within a predetermined crank angle range in which injection is performed, such as from BTDC30° to A T'DC3.
It is also possible to do this only with 0', and in addition to that, 414 to detect glow emission.

Furthermore, it is of course possible to use the ignition timing sensor and the luminescence sensor as separate bodies.

In the embodiment, the glow plug main relay 52
Although the glow plug sub-relay 56 and the glow plug sub-relay 56 are both mechanical relays, it is also possible to replace them with, for example, Darlington-connected switching transistors.

Further, in the embodiment described above, glow emission detection was performed for only one cylinder, but it may be performed for any plurality of cylinders, or for all cylinders.

As described above, according to the present invention, glow humidity can be detected 1' accurately and with good responsiveness without using a glow heater series resistor.

Therefore, the energization state of the glow heater can be controlled with high precision, and the temperature of the glow heater can be controlled to be constant within a narrow range, which has the profound effect of improving engine startability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the overall structure of an embodiment of a glow control device for a diesel engine according to the present invention, FIG. 2 is a cross-sectional view showing the structure of a glow plug used in the embodiment, and FIG. The figure is an enlarged sectional view of part ■ in Figure 2, and Figure 4 is
FIG. 3 is an enlarged sectional view of the section ■ in FIG. 3, FIG. 5 is a circuit diagram showing the glow control circuit of the electronic control unit used in the above embodiment, and FIG. 6 is a circuit diagram showing the glow control circuit of the electronic control unit used in the above embodiment. v
It is a diagram which shows an example of the change state of the glow heater temperature of IFR. DESCRIPTION OF SYMBOLS 10... Diesel engine, 12... Glow plug, 14... Optical fiber, 16... Photodetector, 20... Electronic control unit (ECLI), 30
...Optical fiber, 30A...Tip, 30B
... Glow light emission introduction part, 32 ... Glow heater, 3
4.36...Cylindrical housing. Agent Takayaron (one idiot) Figure 1 14 Figure 3■ Figure 4

Claims (1)

[Claims] (1) Is there a position inside the engine combustion chamber? , a glow plug including a glow heater placed in the combustion chamber and a cylindrical housing that holds the glow heater in a state where the inside of the combustion chamber is isolated from the outside air, and for controlling the energization state of the glow heater according to the heat generation temperature of the glow heater. A glow control device for an engine includes a light guide disposed in the glow plug for guiding light emitted from a glow heater due to excessive glow, and a photodetector for detecting glow light emitted by the light guide. The energization state of the glow heater is controlled according to the temperature of the glow heater detected from the output of the photodetector. 1! A diesel engine glow control device.