JPS585475A - Controller for quick-heating glow plug - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the durability due to the overheating at the heating coil section, by employing the two stage heating of the glow plug where the heat setting resistance at the first stage is made high while it is made low at the second stage. CONSTITUTION:Upon closing of a key switch 2, the super-quick heating of the glow plug 1 is started through a relay contact rl1 to increase the resistance Rg of the heating coil as the temperature rise thus to increase the potential (a) of the bridge circuit and upon reaching to the predetermined level Rs the relay drive 5 is functioned by a comparator C1 through OR gate 3 and delay circuit to open the contact rl1 for the time of the output width of a one-shot multivibrator thus to stop the quick heating and to close the contact rl2a, rl2b resulting in the second bridge circuit comprising the resistors Rg, Re, R3, R4. Upon completion of the output width time, the contact rl1 will reopen to supply the heating current while when the value of Rg reaches to the predetermined value RN the relay drive 5 is functioned by the comparator C2 thus to open the contact rl1 and to stop the heating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a glow plug, which is a starting assist device for a diesel engine.

Die (engine) heats the inside of the combustion mold to improve O logic, but I am omniscient that glow plugs are used to heat the engine.

Conventionally, preheating was performed over a period of 5 to 7 seconds until the temperature of the combustion base reached a constant temperature (approximately 100° C.).

However, waiting for a preheating time of 1 second is difficult for drivers accustomed to gasoline-fueled engines to withstand, so it is desirable to shorten the preheating time by 612°. In order to deal with ζ01HIK, the heating speed will be increased and heating will be done rapidly. If the coil is buried inside the sheath material, such as in the case of putuda, if a large current due to rapid heating is suddenly applied to the glow plug, the coil will generate a large amount of heat. However, on the outside, the temperature jf does not rise until t, or in places where the L coil winding density is high, the temperature rises, but in places with low exposure of 4 IVM degrees, a state occurs where the temperature is low. Therefore, when the heating speed is slow, the entire glow plug is heated gradually, so the temperature difference between the coil part and the outer surface is small and there is no problem. However, with rapid heating, when the outer surface reaches 900°C, the coil part is It is called Amanaro in ℃. This means that when rapidly heating a glow plug,
- If you use a device that calculates the coil resistance based on the temperature of the outer surface and controls the current based on this, the temperature of the outer surface will be 90.
This means that even at 0°C, the internal temperature can reach as high as 1100 u, which causes a severe deterioration in the durability of the glow plug.

Therefore, the present invention solves this problem by heating the round glow plug in two stages. It is an object of the present invention to provide a control device for a rapidly heating glow plug that prevents deterioration of durability of the glow plug due to overheating of the heating coil portion by reducing the temperature.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the relationship between the resistance of the glow plug and the preheating temperature in the case of rapid heating a and the case of slow heating. As shown in the figure, the glow plug resistance for obtaining the set preheating temperature Ts is Rs in the case of rapid heating, but is RM, which is smaller than that in the case of slow heating.

Therefore, by using a control method that detects and controls the resistance Re during rapid heating, after the heating of the glow plug is completed, it is controlled with an easy resistance value to maintain a constant temperature. Since it becomes TM, overheating of the heating coil causes a fusion cape. Therefore, a control device is required to prevent the heating coil from overheating and stabilize the heating of the glow plug.

Figure 2 is a circuit diagram used in a control device for a rapid heating glow plug according to the present invention. EO is the power source, which consists of things like car batteries. 2 is a key switch, r4 is a normally open contact of the first relay, and R is a current detection resistor of the glow plug, which has a value of 1/1o or less of the normal temperature resistance value of the glow plug. 1 is the glow plug, and Rg is the resistance of the heating coil of the glow lug.

The heating current for the glow plug is as follows: power supply Eo-+ life switch 2 → current detection resistor glow plug → power supply E.

It will flow through a circuit. R1s R1m R
4OR4 is a resistor, resistor R1 + R1 and the glow plug's current detection resistor R・, the glow plug's heating coil resistance Rg constitute the first bridge circuit, and the resistor -5R4 and the resistor 8・, Rg constitute the second bridge circuit. Configure a bridge circuit. cl
.

The Co1d Hiei device is set to output when the resistance of the 01 glow plug reaches Rs in Figure 1, and the terminals a and bKIIk of the first bridge circuit are connected, and the resistance of the Csu glow plug is set to RN in the M1 diagram. It is set to output an output when it reaches , and is connected to the terminal aaKil of the second bridge circuit. 3 is a 0 circuit connected to the output terminal of the comparator Ct, C,. 4 is a delay circuit which is applied to the output terminal of the OR circuit. The RLI is a relay drive device made by 5 companies, and is composed of a multi-vibrator made by Domiba Wanshi.

6 is an amplifier connected to the output terminal of the comparator C1.

gh r4B o r&b is the normally open contact of the second relay, and r41 is the self-holding contact of the second relay, and r4b
t[2 bridge-connected to the rounding that activates the motion.

Next, the operation of the circuit will be explained. First, key switch 2
When you turn on the power switch sEo → key switch 2 as mentioned above,
→ Normally closed contact r4 of ag1 relay → Current detection resistor Re →
Current flows from the glow plug 1 to the power source Ro, and ultra-rapid heating of the glow plug begins.

When the glow plug is heated and its temperature rises, the resistance Rg of the heating coil 111 also increases, and at the same time, the potential of the terminal field of the bridge circuit also rises. The resistance Rg of the heating coil is the first
When reaching R8 in the figure, comparator C1 generates an output signal. The output signal of 2 operates the first relay driving device 5 through the OR circuit 5 and the delay circuit 4, and the operation of this driving device causes the V-coil to be activated only during the output time of the driving device's one-piece rotary pipebrator. RL is excited. Relay coil k RLIO excitation activates the relay and its contact r
4 Open to cut off the heating current and stop ultra-rapid heating. On the other hand, the output of the comparator Q is amplified by the amplifier 6 and 9 to excite the coil RL of the second relay. When the second relay is activated, its contacts r41 and r/ab are closed, and the second relay is self-maintained at r14@K, and the aforementioned second circuit is formed at r4b. When the output of the one-shot multivibrator of the driving device 5 is completed, the first
The relay returns and its contact r4 closes again, allowing heating current to flow through the glow pulse again. The temperature of the glow plug drops when the heating is stopped earlier, but the temperature rises again due to this reheating, and the resistance +m Rg of the heating coil increases.
Voltage noise at second bridge circuit terminal & C cabinet increases*k
When go* reaches the value RN in FIG. 1, the comparator C3 outputs an output signal, and this output polarization operates the relay m-tai device via the OR circuit 5 and the delay circuit 4. When the relay drive device is activated, the first relay is activated only during the output of the multi-vibrator, and the heating circuit is opened by relay contact r4 to stop heating. Thereafter, the relay contact r40 is repeatedly opened and closed by the intermittent output of the IJ relay drive device, and the temperature of the combustion chamber is maintained at the preheating set temperature.

As described above in detail, according to the glow plug control device according to the present invention, the heating of the glow plug is divided into two stages, and the first stage heating is performed at the preheating set temperature f during rapid heating. Ts K Resistance value R of corresponding Takuro plug
s is detected to control the heating, and the second stage heating is performed by detecting the resistance value RN of the glow plug corresponding to the preheating set temperature [Ts in slow heating. This prevents deterioration in the durability of the glow plug, such as disconnection or fusing of the heating coil due to overheating, and provides stable heating of the glow plug.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between glow plug resistance and preheating temperature in the case of rapid heating and slow heating, 2nd wr is a control circuit diagram of the glow plug according to the present invention, Eo...power supply, 1
...Glow plug, R...Resistor for current detection, c,
e c, ... comparator, RLI * RLI ... first and second relay coils, r4. r-1r m b...1st
, second relay contact, R1e R1* Rj * R4
...Resistance, 5...OR circuit, 4...Delay circuit, 5
... Relay drive device, 6... Multiplier patent applicant Isuso Jidosha Co., Ltd. agent Tsuji Benshioji 2 people

Claims (2)

[Claims] (1) A glow plug with a heating element whose resistance value changes according to changes in heating temperature, a current detection resistor, a normally closed current control element to which a signal is applied and the 9 and 1 WA paths are opened, and t. A glow plug heating circuit that is connected in series to a power source has calculation devices No. 1 and No. 2 that calculate the resistance value of the heating element based on the voltage generated at both ports of the current detection resistor. 1st and 3112 (1st part that outputs when the calculation result of each D calculation unit exceeds a preset critical value)
and a second comparator; a drive device that drives the current control element and operates upon receiving the 11#I output signal when either the rattan 1 or the 20th comparator issues an output signal; 20
The arithmetic unit is connected in parallel to the glow plug heating circuit, and operates in response to the signal from the first comparator, and when the signal from the tenth comparator stops, 4 self-holding is performed. A control device for a rapid heating glow plug, comprising a drive device for driving the normally open current control element assembly. (2) The setting value of the first comparator is set to be larger than the setting value of the 20th comparator.