JPH0745866B2 - Glow plug abnormality detection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glow plug abnormality detection method for accelerating fuel ignition.

<Background Art> Recently, alternative fuels for gasoline have been studied due to concerns about supply of crude oil, and fuels containing alcohol such as ethanol or methanol have been widely used. Alcohol is partially used as a dedicated fuel. Alcohol engines (low cetane number fuel engines) are also emerging.

In this low cetane number fuel engine, a glow plug for assisting ignition of fuel is provided near the combustion chamber, and the glow plug is constantly energized to generate heat and accelerate ignition.

Since this glow plug is constantly energized and heated during engine operation, strict durability is required. For this reason, a ceramic having a high resistance to high temperature oxidation is used as a material of the heat generating portion at the tip of the glow plug. The glow plug used in the engine described above is temperature-controlled by controlling the energization time in order to improve durability and reduce power consumption. For this reason, the temperature of the glow plug may rise above the set value due to a failure of the controller or the engine. When the heat-generating part of the glow plug reaches a high temperature of about 1300 ° C, the ceramic heat-generating part is instantly damaged. If the ceramic fragments fall into the combustion chamber, the piston, the cylinder chamber, etc. may be damaged and the engine may be damaged.

<Object of the Invention> The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glow plug abnormality detection method capable of reliably detecting an abnormality in the temperature of the glow plug.

<Means for Achieving the Object> The abnormality detecting method for a glow plug according to the present invention for achieving the above object is a glow plug auxiliary engine including a glow plug for promoting ignition of fuel near the combustion chamber of the engine. A method of detecting an abnormality of a glow plug, comprising detecting a temperature value of the glow plug, comparing an increasing rate of the temperature value and a set temperature increasing rate, and increasing rate of the temperature value is the set temperature increasing rate. A feature is that an occupant is warned when the above is reached.

<Examples> Fig. 1 shows a system connection diagram for explaining a glow plug abnormality detection method according to an example of the present invention.

The glow plug 1 provided in the vicinity of an engine combustion chamber (not shown) is controlled in energization by the control unit 2 to generate heat and accelerate ignition of fuel. The temperature of the heat generating portion 1a of the glow plug 1 is detected by a temperature detecting means such as a sensing register and a thermocouple, and the detected temperature value is input to the control unit 2. On the other hand, a warning lamp 3 and a buzzer 4 are provided inside the vehicle,
By the control of the control unit 2, the warning lamp 3 and the switch 5 of the buzzer 4 are turned on and off.

A specific abnormality detection method will be described with reference to FIG. FIG. 2 shows a control block diagram of a glow plug abnormality detection method.

In the control unit 2, the set temperature value of the glow plug 1 is set to 1200 ° C. and the temperature rise rate of the glow plug 1 is set to a predetermined value.

During operation of the engine, the temperature of the heat generating portion 1a of the glow plug 1 is detected by the temperature detecting means, and the detected temperature value of the heat generating portion 1a is input to the control unit 2 every moment.
The temperature value of the heat generating portion 1a input in the control unit 2 is compared with a preset temperature value (1200 ° C.). As a result of the comparison, when the temperature value of the heat generating part 1a becomes 1200 ° C. or higher, the warning lamp 3 and the switch 5 of the buzzer 4 are turned on, the warning lamp 3 lights up and the buzzer 4 sounds and the occupant glow plug 1 Informs of abnormalities. If the temperature value has not reached the set temperature value (1200 ° C), the rate of increase of the temperature value that is input momentarily is compared with the predetermined temperature increase rate value. 5 is ON
And informs the passenger of the abnormality of glow plug 1. When the increase rate of the temperature value is lower, the process returns to the process of comparing the temperature value with the set temperature value.

In the above-described method for detecting an abnormality of the glow plug 1, the warning lamp 3 and the buzzer 4 are activated when the temperature of the heat generating portion 1a of the glow plug 1 becomes equal to or higher than the set temperature value (abnormally rises). Therefore, the occupant can be surely notified of the temperature abnormality of the glow plug 1. Even if the absolute temperature of the heat generating portion 1a is lower than the set temperature value, the warning lamp 3 and the buzzer 4 are operated when the temperature rising rate exceeds the predetermined temperature rising rate value. The temperature abnormality of the glow plug 1 due to the failure of the control unit 2 or the engine can be reliably notified to the occupant.

<Effect of the Invention> In the glow plug abnormality detection method of the present invention, the occupant is alerted when the temperature value of the glow plug becomes equal to or higher than the set value. I can inform you. As a result, damage to the glow plug can be prevented, and a major accident such as engine damage can be prevented.

Further, even when the temperature rise rate of the glow plug caused by the abnormality of the glow plug itself at the time of start-up is extremely large, not only the temperature abnormality of the glow plug but also the abnormality of the glow plug itself can be notified to the occupant. . As a result, it is possible to prevent the catalyst and the filter provided in the exhaust pipe from being damaged by replacing the abnormal glow plug with a normal glow plug, whereby the exhaust gas temperature becomes abnormally high.

[Brief description of drawings]

FIG. 1 is a system connection diagram for explaining a glow plug abnormality detection method according to an embodiment of the present invention, and FIG. 2 is a flowchart of the glow plug abnormality detection method. In the drawings, 1 is a glow plug, 2 is a control unit, 3 is a warning lamp, 4 is a buzzer, and 5 is a switch.

Claims (1)

[Claims] 1. A method for detecting an abnormality of a glow plug of a glow plug auxiliary engine comprising a glow plug for promoting ignition of fuel in the vicinity of a combustion chamber of the engine, the temperature value of the glow plug being detected, A method for detecting abnormality in a glow plug, which compares an increase rate of the temperature value with a set temperature increase rate, and issues a warning to an occupant when the increase rate of the temperature value exceeds the set temperature increase rate. .