JPS6324151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention instantly raises the temperature of a glow plug installed in an internal combustion engine such as a diesel engine to the complete explosion temperature of the engine, and optimally controls the temperature of the glow plug after the temperature rise. The present invention relates to an energization control device for.

A glow plug that initially supplies a large current to the glow plug to quickly raise its temperature for preheating, and once the glow plug reaches a predetermined temperature, a small current is supplied to maintain the temperature to maintain the glow plug at a predetermined temperature for a certain period of time. Plug energization control devices have been proposed to shorten the preheating time, but even such energization control devices usually require a preheating time of about 10 seconds, which is a drawback of diesel engines. In order to eliminate this drawback, the preheating time can be shortened to about 1 to 2 seconds, but if such a rapid temperature increase rate is adopted, the temperature of the glow plug can be adjusted to the appropriate temperature required for complete explosion of the engine (normally It became difficult to keep the temperature at 800°C to 1000°C, and problems such as heating elements melting down due to excessive temperature rise to 1200°C or higher occurred. A complete explosion is a state in which ignition and combustion occur normally in the engine combustion chamber.

An object of the present invention is to provide a glow plug energization control device that can shorten the preheating time to 1 to 2 seconds or less, eliminate the waiting time for preheating, and start energizing the starter motor at the same time as the glow plug starts energizing. Another object of the present invention is to provide a glow plug energization control device that can easily control the temperature of the glow plug and reliably prevent excessive temperature rise in such a device.

Next, the present invention will be explained based on an embodiment shown in the drawings.

Figure 1 shows the preheating device of a diesel engine.
is a battery, G is a glow plug, S is a key switch, GL is a glow plug energizing terminal of a key switch, ST is a starter/motor energizing terminal of a key switch, and 1 is a glow plug energization control device according to the present invention. The energization control device 1 controls current through an energization control relay for supplying a large current to the glow plug G and a current control resistor R ₁ for controlling the temperature increase rate of the glow plug G within a range where temperature control is easy. an energization control relay that causes a current to flow through a composite resistance of the current limiting resistors R ₁ and R ₂ to keep the glow plug heated to the constant temperature; , a control circuit 2 that controls the opening/closing time of the glow plug G
Glow plug temperature detection device 3 connected in series with
It consists of a resistor _R3 . As shown in FIG. 2, the control circuit 2 receives the temperature signal t from the temperature detection device of the glow plug G and the set lower limit temperature of the engine
Comparator C ₁ which takes input t ₁ and controls the relay.
and a comparator C ₂ which controls the relay by inputting the temperature signal t and the set appropriate temperature t ₂ for complete explosion of the engine.
and a timer _T1 that receives the energization signal to the glow plug G and controls the relay. In this embodiment, as shown in FIG. 3, the timer _T1 includes an RC charging circuit 11 for determining a time constant, a reference voltage setting circuit 12 consisting of resistors _R11 and _R12 , and a discharging circuit 13 for a capacitor C. The transistor _Q1 and the comparator _C3 form the timer _T1 and the comparator _C2.
The output of the AND circuit 4 is input to the AND circuit 4, and the relay is controlled by the output of the AND circuit 4.

Next, the operation of the energization control device 1 will be explained with reference to the waveform diagram in FIG. 4.

In order to start the engine, the driver turns on the key switch S to the terminal ST as shown in Figure 4A, and the comparators _C1 , _C2 and timer _T1 generate high level outputs and the relay is activated as shown in Figure 4B. ,, are all
is turned ON, and energization of glow plug G and starter motor are started at the same time or almost at the same time. Since the glow plug G is directly connected to the battery via a relay, a large current is supplied to the glow plug G. Since the temperature increase rate at this time is set to about 400°C/sec to 800°C/sec, the glow plug G reaches the engine's lower limit temperature for complete explosion t ₁ (600°C to 800°C), as shown in Figure 4 C.
The temperature rises rapidly in about 1 second. When the glow plug G reaches the lower limit temperature _t1 , the output of the comparator _C1 is reversed to low level, so the relay is turned off.
becomes. Thereafter, the glow plug G is energized by the relay and the energization control resistor R ₁ and the combined resistance of R ₁ +R ₂ respectively. The temperature increase rate of the glow plug G at this time is about 1/4 to 2/3 slower than the temperature increase characteristic up to t ₁ , and is approximately 100℃/second to 200℃/second. Ru. By doing this, the appropriate temperature for complete explosion t ₂ (800℃
-1000° C.) is sufficiently gentler than the temperature increase gradient up to the lower limit temperature _t1 , so the accuracy of temperature detection and control can be easily guaranteed.
After the glow plug G reaches the appropriate temperature _t2 , if it is continuously energized through the resistor _{R1 and} left, the glow plug G will reach the upper limit temperature of the heating element in about 10 seconds.
Since the temperature exceeds 1200℃, comparator _C2 turns off the relay. When the relay is turned off, the relay energizes the glow plug G with the combined resistance of R ₁ + R ₂ to soften the temperature drop of the glow plug. However, the temperature of glow plug G is the lower limit temperature.
When the temperature falls below t' ₂ , which is set between t ₁ and the appropriate temperature t ₂ , the output of comparator C ₂ is reversed to high level, the relay is turned on again, and the temperature of glow plug G becomes
It rises again to t ₂ . This operation continues repeatedly until the key switch S is turned off or the output of timer _T1 , which will be described later, is turned off.

The engine begins to rotate on its own due to the ignition deflagration in the combustion chamber when the glow plug reaches the lower limit temperature for complete explosion, _t1 , or 1 to 2 seconds thereafter, and the engine starts to complete, but if the driver presses the key switch S. By connecting to the GL terminal, the glow plug G maintains the temperature required for complete explosion for the time period set by timer _T1 for afterglow, ensuring smooth operation immediately after startup.

The timer T ₁ energizes the glow plug G via _the relay from the connection to the terminal ST.
However, by providing a discharge circuit 13 for updating the set time, the set time _T11 starts when the operator returns the key switch from terminal ST to terminal GL after starting the engine. ,
This period is the after blow. Also, the energization time by the relay is determined by inputting the output of the comparator C ₂ and the output of the timer T ₁ to the AND circuit 4 as in this embodiment.
By controlling the relay with the AND circuit 4, the output time of the timer _T1 is reached until the end of the output time limit _T11 .

As described above, the glow plug energization control device according to the present invention includes an energization control relay for supplying a large current to the glow plug, and a current limiter for controlling the temperature increase rate of the glow plug within a range that is easy to control. An energization control relay that causes current to flow through a resistor, an energization control relay that causes current to flow through a current limiting resistor to keep the glow plug warm after it has risen to a set temperature, and controls the opening/closing time of the aforementioned relays. It consists of a control circuit that instantly raises the temperature of the glow plug to the lower limit temperature required for complete explosion, and then lowers the temperature increase rate from the lower limit temperature to an appropriate temperature to facilitate temperature control of the glow plug and suppress the glow. Preheating time is 1 to 1 to prevent overheating of the plug.
The time can be shortened to less than 2 seconds, eliminating the waiting time for preheating, making it possible to start energizing the starter motor at the same time as energizing the glow plug, and making it easy to control the temperature of the glow plug to ensure that there is no excessive temperature rise. It can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a preheating device for a diesel engine equipped with a glow plug energization control device of the present invention, FIG. 2 is a block diagram of the energization control device, and FIG. 3 is a circuit diagram of a timer _T1 with a discharge circuit. FIG. 4 is a waveform diagram for explaining the operation. 1... Glow plug energization control device, 2... Control circuit, ,... Relay.

Claims (1)

[Scope of Claims] 1. The temperature detection means includes: a rapid temperature increase glow plug; a temperature detection means for detecting the temperature of the glow plug; and a rapid temperature increase energization relay that supplies a large current directly to the glow plug. a comparator _C1 that controls the energizing relay based on a signal and energizes the glow plug by the energizing relay when the temperature of the glow plug is less than the lower limit temperature _t1 ; A timer _T1 that starts operation and outputs an output for a set time period, and an energization control relay that supplies a current that can control the temperature to the glow plug via a current limiting resistor _R1 , based on the signal of the temperature detection means. controls the control relay, and when the temperature of the glow plug is less than the appropriate complete explosion temperature _t2 set to the lower limit temperature t1 _or higher while the timer _T1 is operating, the control relay controls the glow plug. a comparator _C2 that is energized, and a current _limiting resistor that is
An energization control relay that supplies current to the glow plug via R ₁ and a current limiting resistor R ₂ , and a energization signal to the starter motor that reactivates the timer T ₁ to energize the starter motor. and a re-activating means for activating the starter motor for a set time after the energization signal to the starter motor is stopped. 2. The glow plug energization control device according to claim ₁ , wherein an integrated three-terminal type resistor is used for the current limiting resistor R1 and the current limiting resistor _R2 . 3 The temperature increase rate when the glow plug is energized is:
20 if done through said energizing relay
C/sec or more, and when carried out via the energization control relay, the rate of temperature increase is 90% or less of the temperature increase rate when carried out via the energization relay. energization control device for glow plugs.