JPS61244853A - Stop of operation of diesel engine - Google Patents

Abstract

PURPOSE:To smoothly stop the engine operation without generating large vibration by setting in variable ways the valve closing delay time of a fuel cut-off valve after the turning-OFF of a key switch according to the opening quantity of an intake cut-off valve in a specific state. CONSTITUTION:A main intake throttle valve 18 and a subintake throttle valve 19 are installed into an intake passage. The valve closing delay time of a fuel cut-off valve 27 is set in variable ways according to the valve opening position of the subintake throttle valve 19 immediately before the turning-OFF of a key switch 53, and the closing of the fuel cut-off valve 27 is carried out at the time suitable for the intake cutting-off action by the subintake throttle valve 19, even if the subintake throttle valve 19 is at the perfectly opened or neutral position. Thus, the operation of Diesel engine can be smoothly brought into stop without generating large vibration.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for stopping the operation of a diesel engine.
In particular, the present invention relates to a method for stopping the operation of an f-easel engine having an intake cutoff valve and a fuel cutoff valve.

Conventional technology Some diesel engines have an intake cutoff valve (intake throttle valve) that throttles and shuts off the intake air in the middle of the intake passage. After the intake air is shut off by the valve, the fuel injection pump is shut down a little later, and the fuel shutoff valve shuts off the fuel. In view of this, a patent application has been made for a method and apparatus for stopping diesel engines, which first shut off the intake air with an intake cutoff valve and then cut off the fuel with a fuel cutoff valve when the engine is stopped. 5
This method has already been proposed in Japanese Patent Application No. 7-12861 (Japanese Unexamined Patent Publication No. 58-131339) and Japanese Patent Application No. 57-125566 (Japanese Unexamined Patent Publication No. 59-15645).

Problems to be Solved by the Invention In order to stop the operation of a diesel engine smoothly without causing large vibrations, the fuel cutoff valve has an intake cutoff well positioned in a fully closed position to effectively cut off the intake air. It is preferable to close the valve and cut fuel when a predetermined time of about 1/10 seconds has elapsed from the start of the operation. The fuel cutoff valve closes when a certain amount of time has elapsed, and therefore, the intake cutoff will be different depending on whether the opening of the intake cutoff valve is large or small just before the key switch is turned off. Due to the difference in the time required for the valves to open, the fuel cutoff valve does not necessarily cut off the fuel after a predetermined time has elapsed, which is more preferable than when the intake cutoff valve is in the fully closed position.
The timing of the fuel cut may be too late or too early compared to the time when the intake air is shut off by the intake air shutoff valve, and the diesel engine may not be stopped smoothly without causing large vibrations. There is.

In view of the above-mentioned problems in the conventional method for stopping the operation of diesel engines, the present invention has been devised so that no matter what the opening degree of the intake cutoff valve is just before the key switch is turned off, the intake cutoff valve can actually The fuel is cut off by the fuel cutoff valve when a preferable predetermined time has elapsed since the intake cutoff was performed, and the opening degree of the intake cutoff valve immediately before the key switch is turned off is large regardless of the IFt1 degree. The object of the present invention is to provide an improved method for stopping the operation of a diesel engine so that the operation of the diesel engine can be stopped smoothly without vibration.

Means for Solving the Problems According to the present invention, an intake cutoff valve is provided in the middle of an intake passage and selectively closes the intake passage;
In a method for stopping the operation of a diesel engine having a fuel cutoff valve provided in the middle of a fuel passage and selectively closing the fuel passage, when a key switch is turned off, the air intake 'a' is substantially simultaneously shut off. bring the valve to the fully closed position, bring the fuel cutoff valve to the closed position after a predetermined time has elapsed since the key switch was turned off, and set the closing delay time of the fuel cutoff valve when the key switch is in the off state. This is achieved by a method for stopping operation of a diesel engine characterized in that when the opening amount of the intake cutoff valve immediately before the intake shutoff valve is opened is large, the opening amount is increased compared to when it is small.

Effects and Effects of the Invention According to the operation stop method of the present invention, the closing delay time of the fuel cutoff valve after the key switch is turned off is equal to the closing delay time of the intake cutoff valve immediately before the key switch is turned off. By setting the value variably according to the amount of valve opening, the fuel cutoff by the fuel cutoff valve is actually performed by the intake cutoff valve regardless of the amount of opening of the intake cutoff valve immediately before the key switch is turned off. This is done after a preferable predetermined period of time has elapsed since the intake throttling was performed, and as a result, large vibrations are always generated regardless of the opening amount of the intake cutoff valve immediately before the key switch is turned off. The diesel engine can be stopped smoothly without any problems.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 shows one embodiment of a diesel engine and its IT, II control device on which the shutdown method according to the present invention is implemented. In the figure, reference numeral 1 designates a diesel engine, which has a cylinder bore 2 in which a piston 3 is slidably received in the vertical direction as shown in the figure. Room 4 is defined.

The diesel engine 1 has a swirl chamber 6 that communicates with a combustion chamber 4 through a jet nozzle 5, and fuel is injected into the swirl chamber from a fuel injection nozzle 7.

The fuel injection nozzle 7 is connected through a fuel conduit 8 to a fuel injection pump 9, from which fuel is pumped at a metered flow rate depending on the engine load and approximately the duration of depression of the accelerator pedal 10.

The fuel injection pump 9 is provided with an electromagnetic fuel cutoff valve 27, which is known per se. The fuel cutoff valve 27 is configured to open when energized to communicate with a fuel passage (not shown) in the pump, and to close when de-energized to block the fuel passage.

The diesel engine rlJ1 takes in air into the combustion chamber 4 from an intake port (not shown) through the intake control 18 and the intake manifold 12, and discharges exhaust gas from the combustion chamber 4 through the exhaust port 13 to the exhaust manifold. It looks like this. The intake and exhaust ports 13 are each opened and closed by a poppet valve, and in the figure, only the exhaust poppet valve is shown by reference numeral 15.

The intake-m+ device 11 has a main intake passage 16 and a sub-intake passage 17 which are provided in parallel with each other. are each provided with a sub-intake throttle valve 19.

The main intake throttle valve 18 is drivingly connected to the accelerator pedal 10 by an accelerator linkage 20 and
When the accelerator pedal 10 is released, it is in the fully closed position as shown in the figure, and opens in response to the accelerator pedal 10 being depressed.

The auxiliary intake throttle valve 19 is drivingly connected to the double diaphragm device 21, and when atmospheric pressure is introduced into both of its diaphragm chambers 22 and 23, it is in the fully closed position as shown in the figure, and the diaphragm chamber 22 is in the fully closed position. When negative pressure is introduced into the diaphragm chamber 23 due to the introduction of human pressure, it is located at the intermediate (half-open) position, and when negative pressure is introduced into both the diaphragm chambers 22 and 23, it is located at the fully closed position. It looks like this.

The diaphragm chamber 22 of the double diaphragm device 21 is connected to a negative pressure control valve 24, and the diaphragm chamber 23 is connected to another negative pressure control valve 25. The negative pressure control valves 24 and 25 are each electromagnetically actuated negative pressure control valves, and when energized, introduce the negative pressure from the negative pressure supply device 26, which includes a negative pressure pump and a negative pressure tank, into the diaphragm chamber 22 or 23. When the power is not energized, atmospheric pressure is applied to the diaphragm chamber 22 or 2.
3, and this energization control is performed by a control device 50.

The control device a50 includes a microcomputer with a general structure, and detects the diesel engine 1 from the rotation speed sensor 51.
The starter switch 52 provides information regarding the rotation speed of the engine, the key switch 53 provides information regarding its opening/closing, the water temperature sensor 54 provides information regarding the engine cooling water temperature, and the accelerator sensor 55 provides information regarding the accelerator pedal 10. 01' for the amount of depression? According to this information, the energization to the negative pressure control valves 24 and 25 is individually controlled, and the energization to the fuel cutoff valve 27 is controlled.

The control device 50 operates during engine starting when the starter switch 52 is closed and during low-temperature idling operation when the key switch 53 is closed and the engine cooling water temperature detected by the water temperature sensor 54 is a predetermined value, for example, 60° C. or less. An off signal is output to both the negative pressure υIII valves 24 and 25, and an on signal is output only to the negative pressure control valve 24 during idling after warming up when the engine cooling water temperature is above a predetermined value.
3 is opened when the engine is stopped or in fail-safe mode, both the negative pressure control valves 24 and 25 are It is designed to output an on signal.

Therefore, the auxiliary intake throttle valve 19 is brought to the full position during startup and low-temperature idle operation, and is brought to the open position during idle operation after warming up, and the key switch 52 is opened to operate the diesel engine 1. A fully closed position is provided to act as an intake shutoff valve when the valve is shut down and in fail-safe mode.

Next, the auxiliary intake throttle valve (intake cutoff valve) 19 and the fuel cutoff valve 27
The method for shutting down a diesel *rJQ according to the present invention using the following will be explained using the flowchart shown in FIG. 2 and the time charts shown in FIGS. 3 to 5.

The flowchart shown in FIG. 2 shows a part of the main routine, and in step 100, 1. Whether or not the key switch 53 has switched from the on state to the off state;
That is, it is determined whether the key switch 53 is opened or not. When the key switch 53 is not opened, that is, when the engine is continuing to operate, the process proceeds to step 101. On the other hand, when the key switch 53 is opened, that is, when the engine is stopped, the process proceeds to step 106.

In step 101, it is determined whether the auxiliary intake throttle valve 19 is in the fully closed position. This determination is made by the control device 5.
0 may be performed based on the signals output to the negative pressure control valves 24 and 25. When the sub-intake throttle valve 19 is in the fully closed position, the process advances to step 103; If it is not in the closed position, the process advances to step 102.

In step 102, it is determined whether the auxiliary intake throttle valve 19 is in the intermediate position. When the auxiliary intake throttle valve 19 is in the intermediate position, the process proceeds to step 1.04, whereas when the auxiliary intake throttle valve 19 is not in the intermediate position, the process proceeds to step 1.
Proceed to 05.

Step 103 is executed when the a1 intake comparison valve 19 is in the fully closed position, and in this step, the fuel cutoff valve 27 is
The target valve closing delay time Tt is set to the first predetermined time T'+. This first predetermined time T! is determined according to the time required for the auxiliary intake throttle valve 19 to move from its fully closed position to the fully closed position, and is, for example, 0.7.
It is set to about 0.9 seconds.

Step 104 is executed when the auxiliary intake throttle valve 19 is in the intermediate position, and in this step, the target opening delay time 1-t of the fuel cutoff valve 27 is set to a second predetermined time T2. be exposed. The second predetermined time T2 is determined according to the time required for the auxiliary intake throttle valve 19 to move from the intermediate position to the fully closed position, and is set, for example, to about 0.1 to 0.3 seconds.

Step 105 is executed when the auxiliary intake throttle valve 19 is already in the fully closed position, and in this step, the target valve opening delay time 7't of the fuel 'a disconnection arai 7 is set to 0 seconds. be exposed.

Step 106 is executed when the key switch 53 is switched from the OFF state to the OFF state and the operation of the diesel engine is stopped.
, 104 or 105.
The target valve opening delay time 6T2 is set as a timer (flT) for setting the valve closing delay time. After step 106, the process advances to step 107.

In step 107, an ON signal is output to both negative pressure control valves 24 and 25.

As a result, the sub-intake throttle valve 19 is located at the fully closed position, and the sub-intake passage 17 is opened and closed. At this time, since the accelerator pedal 10 is normally released, the main intake throttle valve 18
The main intake passage 16 is also located in the fully closed position.
is also closed, and air intake is cut off. After step 107, the process advances to step 108.

In step 108, it is determined whether the key switch 53 is in the OFF state, that is, in the open state, in order to confirm that the operation has been stopped. If the key switch 53 is not in the off state, fuel cut control is avoided, and if the key switch 53 is in the off state, the process proceeds to step 109.

In step 109, the timer value "" is decremented by a predetermined value Δt.

After step 109, the process advances to step 110.

In step 110, it is determined whether the timer value T is O or less. When T≦0, the process proceeds to step 101, and when 1゛≦O, steps 111 and 112 are skipped.

In step 111, power supply to the fuel cutoff valve 27 of the fuel injection pump 9 is stopped. As a result, a fuel passage (not shown) in the fuel pump 9 is closed, and the fuel is cut off.

After step 111, the process advances to step 112.

In step 112, the timer value T is set to O.

By performing the operation stop control according to the flow chart as described above, the fuel cutoff valve 27 is opened according to the opening position of the auxiliary intake throttle valve 19 immediately before the switch 53 is turned off, that is, immediately before the engine is stopped. Even if the sub-intake throttle valve 19 is at the fully closed position or an intermediate position immediately before the engine stops, the closing of the fuel cut-off valve 27 causes the sub-intake control valve 19 to perform an intake cut-off action. The stoppage of the aircraft 111 is carried out smoothly without any large-scale photographing at any time.

In the above-described embodiment, the opening position of the sub-intake throttle valve 19 is controlled in two stages: fully closed and slightly open.
The valve closing delay time of the fuel cutoff valve 27 is also variably controlled in two stages, and when the opening degree of the fuel cutoff valve 19 has more stages or is continuously controlled, the valve closing delay time of the fuel cutoff valve 27 is changed. may be set stepwise or continuously to a value corresponding to the opening amount of the auxiliary intake throttle valve 19.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine and a control device used to carry out the method for stopping operation of a diesel engine Ia according to the present invention, and FIG. 2 shows the method for stopping operation of a diesel engine according to the present invention. Fruit/71! A flowchart showing an example of the procedure, and FIGS. 3 to 5 are time charts of the method for stopping operation of a diesel engine according to the present invention. 1... Diesel engine, 2... Cylinder bore, 3...
... Piston, 4... Combustion chamber, 5... Nozzle, 6...
- Vortex chamber. 7...Fuel injection nozzle, 8...Fuel conduit, 9...
Fuel injection pump, 10... Accelerator pedal, 11...
・Intake control device, 12... Intake manifold, 13・
...Exhaust boat, 15...Poppet valve, 16...Main intake passage, 17...Sub-intake passage, 18...Main intake throttle valve, 19...Sub-intake throttle valve, 20... Accelerator linkage, 21...Diaphragm device, 22.23.
...Diaphragm chamber. 24.25... Negative pressure control valve, 26... Negative pressure supply device. 27...Fuel cutoff valve, 50...Control device, 51...
・Rotation speed sensor, 52...Starter switch, 53・
...Key switch, 54...Water temperature sensor, 55...
accelerator sensor

Claims (1)

[Claims] A method for stopping the operation of a diesel engine having an intake cutoff valve provided in the middle of an intake passage and selectively closing the intake passage, and a fuel cutoff valve provided in the middle of a fuel passage and selectively closing the fuel passage. The intake cutoff valve is brought to a fully closed position substantially simultaneously when the key switch is turned off, and the fuel cutoff valve is brought to a closed position after a predetermined period of time has elapsed since the key switch was turned off. The valve closing delay time of the fuel cutoff valve is increased when the opening amount of the intake cutoff valve immediately before the key switch is turned off is large compared to when the opening amount is small. How to stop a diesel engine.