JPH0643824B2 - Method and device for starting diesel engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for supplying compressed air into a combustion chamber to start a diesel engine, and a device for starting a diesel engine using the above method. Is.

[Prior art]

The diesel engine is difficult to start when the outside temperature is low.

The reason is as follows. At low temperatures, the lubricating oil and fat becomes highly viscous, giving a large resistance to the rotation of the engine, reducing the starting rotation speed, and hindering the temperature rise due to adiabatic compression. This impediment to adiabatic compression, combined with the low temperature of intake air and atomized fuel, makes ignition and complete explosion of fuel atomization difficult.

Japanese Utility Model Laid-Open No. 60-141476 is known for improving the starting characteristics of the air-started diesel engine.

The conventional technique described in Japanese Utility Model Publication No. 60-141476 is as follows.
If the engine speed is N ₁₀ , the ignition is successful, and if the engine speed is N _20, it is determined that the ignition is unsuccessful. Compressed air is injected until the engine speed reaches N ₁₀ , and compressed air is shut off when the engine speed reaches N _10. ,
After that, if the number of revolutions drops to N _20, it is determined that the ignition has failed, and compressed air is re-injected after a predetermined time. Therefore, even if the outside temperature is low, half of the oil is left in the lubricating oil of the engine. The solid matter is fluidized to reduce its viscous resistance, which reduces the resistance to the starting rotation and facilitates complete explosion.

[Problems to be Solved by the Invention]

By the way, in a diesel engine that performs emergency diesel power generation, it is extremely important to properly control the amount of compressed air consumed. However, in the conventional technology described above, the compressed air is supplied until the rotational speed reaches N _10. Therefore, the charging time is not always constant, and the charging time changes depending on the outside temperature, etc., and it is difficult to control the amount of compressed air consumed accurately.

The present invention provides a method and an apparatus capable of reliably starting a diesel engine while accurately grasping a finite amount of compressed air stored in a compressed air tank by improving the above-mentioned problems of the conventional technology. It is something to do.

[Means for Solving the Problems]

In order to achieve the above object, a method for starting a diesel engine according to the present invention is to supply compressed air in a compressed air tank to a diesel engine for a predetermined time, and to supply the compressed air for a predetermined time. If the explosion is not completed, the supply of compressed air is stopped once, and after a predetermined time interval, compressed air is supplied again for a predetermined time.
The feature is that the stop is repeated a set number of times.

The starting device for a diesel engine according to the present invention is provided with an automatic control device for opening and closing the starting valve in the compressed air supply line from the compressed air tank to the diesel engine, and the automatic control device as described above. Comprises a means for detecting the complete explosion of the diesel engine, a timer means for setting the opening time and closing time of the start valve, and means for detecting whether or not the number of times the start valve is opened is within a set number of times, When the number of opening of the starting valve is within a set number of times, the starting valve is opened and closed at a time interval set by the timer means until the complete explosion of the diesel engine.

[Action]

According to the method of the present invention, the compressed air is supplied and stopped repeatedly to intermittently supply the compressed air, so that even if a semi-solid substance is generated in the lubricating oil of the engine due to a decrease in the outside air temperature, it flows. Since the viscous resistance is reduced by virtue of the fact that the compressed ignition is performed, the compressed ignition can be performed reliably, and in particular, in this case, the supply of compressed air is repeated for a fixed time and stopped for a fixed time. The amount can be accurately controlled, and therefore, the amount of residual air in the compressed air tank can be accurately controlled when the starting operation is interrupted when the complete explosion does not occur despite the set number of starts.

〔Example〕

FIG. 2 is a block diagram of the starting device of the present invention configured to carry out the starting method of the present invention.

When a power failure signal is input to the operating condition circuit 8, a diesel engine operating command is output to the timer circuit 7. The timer circuit 7 outputs a start valve opening request to the open / close circuit 6 for a certain period of time,
The start valve 3 is opened, compressed air is supplied from the air tank 4 to the diesel engine 1, and the diesel engine 1 is rotated to operate the generator 2.

In this embodiment, the operation of the diesel engine 1 and the generator 2 is
It is detected by the number of rotations of the generator 2, and the success or failure of complete explosion (independent rotation) at the time of starting is also detected by this.

The compressed air is supplied to the air tank 4 by incorporating the contact of the pressure switch of the air tank 4 into the on / off circuit 9 and operating the air compressor 5.

When the diesel engine 1 does not operate in response to the start valve opening request from the timer circuit 7 for a certain time, the start valve 3 is closed and the start valve 3 is opened again after a certain time. This operation is repeated several times.

FIG. 3 is a system diagram showing the configuration of the entire plant in this embodiment.

In this example, two electric pumps (6 KV) 12 are installed, and drive power is normally supplied from the power receiving facility 21.

In case of power failure in this device, the electric pump 12
It becomes impossible to operate the stand. At this time, the diesel engine 1 drives the generator 2.

FIG. 1 is a flow chart of an example in which the starting method of the present invention is carried out by using the starting device (FIG. 2).

At step S1, the start command for the diesel engine 1 is confirmed, and at step S2, the diesel engine start valve (reference numeral 3 in FIG. 2) is opened.

In step S3, it is confirmed whether or not the diesel engine 1 has shifted to a self-sustaining operation state (complete explosion). This confirmation is performed by the sensor 2a of the rotation speed shown in FIG.

When the complete explosion does not occur, the step S4 calculates the number of times the compressed air is fed, and if it is within the predetermined number of times, the start valve 3 (see FIG. 2) is set by the step S5 via the timer T ₁ . ) Is closed and the timer T ₂ waits for a predetermined time, and then the process returns to step S 2 to repeat the above-mentioned operation.

When the complete explosion is successful, or when the complete explosion is not achieved even if the compressed air is supplied a predetermined number of times, the routine proceeds to step S6, where the start valve 3 is closed.

It is natural to close the start valve when the complete explosion is successful. However, if the complete explosion is not achieved even after the compressed air is supplied a predetermined number of times, it must be suspected that a failure has occurred somewhere.

If the starting operation is repeated without exhausting this failure and the stored compressed air is used up, the starting becomes almost impossible (the compressed air should be stored in the air tank 4 again.
It is usually extremely difficult to store compressed air in the air tank 4 again under the circumstance that the emergency diesel power generation must be performed).

Therefore, if the start fails several times (three times in the present embodiment), the feed of compressed air is temporarily stopped and the cause of unstartability is sought before the compressed air is exhausted. Must be eliminated.

When carrying out the present invention, the number of intermittent feedings of the compressed air can be arbitrarily set.

FIG. 4 is a time chart in this embodiment (predetermined number of times: 3 times).

FIG. 4 (A) shows a case where a complete explosion (starting succeeds) occurs once. That is, this is the case where the start valve is opened in response to the start command signal of the diesel engine, and a complete explosion occurs in one stroke, and the "diesel engine operating curve" rises.

FIG. 4 (B) shows the case where the engine is started three times. The t ₁ and t ₂ entered in FIGS. 4 (B) and 4 (C) represent the time intervals given by the timers T ₁ and T _{2 in} FIG. 1, respectively.

FIG. 4 (C) shows the case where the opening and closing of the starting valve is repeated three times and the complete explosion is not achieved.

〔The invention's effect〕

According to the starting method of the present invention, the semi-solid component in the lubricating oil and fat is fluidized by the intermittent starting rotation by the intermittent supply of the compressed air even in the cold, so that the complete explosion can be surely achieved. In addition, the amount of compressed air consumed in that case can be accurately controlled to accurately manage the amount of residual air in the compressed air tank.

Further, according to the starting device of the present invention, it is possible to easily carry out the above-mentioned starting method and sufficiently exert its effect.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the starting method of the present invention. FIG. 2 is a block diagram showing an embodiment of the starting device of the present invention. FIG. 3 is a system diagram for explaining the overall configuration of the plant in the above embodiment. FIG. 4 is a diagram illustrating the time chart in the above embodiment. 1 ... Diesel engine, 2 ... Generator, 3 ... Start valve, 4
...... Air tank, 5 ...... Air compressor (compressor), 11
...... Circuit breaker.

Claims (2)

[Claims] 1. A method for starting a diesel engine equipped with a pneumatic starting device, wherein compressed air in a compressed air tank is supplied to the diesel engine for a predetermined time, and the compressed air is supplied for a predetermined time. When the diesel engine does not completely explode, the supply of compressed air is temporarily stopped, the compressed air is supplied again for a predetermined time after a predetermined time interval, and the supply and stop of the compressed air are repeated a set number of times. How to start a diesel engine. 2. A device for supplying compressed air in a compressed air tank into a combustion chamber to start a diesel engine, wherein a starting valve is provided in the compressed air supply line, and the starting valve is automatically opened and closed. The automatic control device includes a device for detecting a complete explosion of a diesel engine, a timer device for setting an opening time and a closing time of the starting valve, and a number of times the starting valve is opened within a set number of times. And a means for detecting whether the start valve is opened or closed at a time interval set by the timer means until the complete explosion of the diesel engine when the number of times the start valve is opened is within a set number. A starting device for a diesel engine characterized by the above.