JPS6233419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stopping a diesel engine.

Diesel engines do not control the amount of intake air, but instead control the load by controlling the amount of fuel injection.
In other words, the speed is regulated, and the fuel passage is closed by a fuel cutoff valve provided in the fuel injection pump, and the fuel injection pump is stopped by stopping the supply of fuel.

In addition, in diesel engines, if the intake passage is blocked when the engine is stopped, the engine will stop smoothly without large vibrations, and for this reason, large diesel engines require a manual intake cutoff valve. Some are installed in the intake system.

The applicant who is the same as the applicant of the present application is
In No. 134580 (Japanese Patent Application Laid-Open No. 58-35241), we have already developed a device that automatically shuts off the intake air when the engine is stopped using a single valve installed in the intake system, thereby reducing engine vibration when the engine is stopped. I'm proposing it.

The inventors of the present application conducted a more detailed experimental study on engine vibration when a diesel engine is stopped, and found that they first closed the intake passage with an intake shutoff valve, thereby reducing the engine speed. Later, it was discovered that it is more preferable to completely stop the diesel engine by stopping the fuel supply to the fuel injection nozzle in order to reduce engine vibration when the engine is stopped.

It is an object of the present invention to provide a method for stopping a diesel engine based on the above-mentioned recognition. A method for stopping a diesel engine having an intake cutoff valve that closes and a fuel supply stop means provided in the middle of a fuel passage for selectively stopping fuel supply to a fuel injection nozzle, wherein the fuel supply stop means stops the fuel supply. This is achieved by a method of stopping a diesel engine, which is characterized in that the intake cutoff valve is closed in advance.

The fuel supply stop means is disclosed in Japanese Unexamined Patent Application Publication No. 1986-
A fuel cutoff valve that selectively closes a fuel passage, as shown in Japanese Patent Publication No. 83528, or a fuel cutoff valve that selectively closes a fuel passage, or
As shown in No. 139965, a fuel overflow valve for selectively draining and opening the fuel pumping chamber of a fuel injection pump is considered.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of a diesel engine equipped with a device for carrying out a stopping method according to the present invention. In FIG. 1, reference numeral 1 designates a diesel engine, which has a cylinder bore 2, into which a piston 3 is received. The piston 3 defines a combustion chamber 4 above it. The diesel engine 1 has a swirl chamber 5, into which liquid fuel for the diesel engine is injected and supplied from a fuel injection nozzle 6.

The diesel engine 1 sucks air into the combustion chamber 4 through an intake tube 7, a valve housing 8, an intake manifold 9, and an intake port (not shown), and the exhaust manifold 1 through an exhaust port 10.
Exhaust gas is discharged to 1. The intake port and the exhaust port 10 are each opened and closed by a poppet valve, and the reference numeral 1 in the figure
Only the poppet valve for exhaust is indicated by 2.

Attached to the valve housing 8 is a butterfly-type intake valve 14 carried by a valve stem 13, as best shown in FIG. Intake valve 1
4 is a fully open position as shown by a solid line in the figure, a middle open position (intake throttle position) as shown by a phantom line, and a fully closed position (closed position) as shown by an imaginary line. ). One end of a lever 15 is fixed to the valve stem 13, and the other end of the lever 15 is drivingly connected to a rod 17 of a diaphragm device 16. The diaphragm device 16 is a two-stage type having two diaphragm chambers 18 and 19, and when negative pressure is not introduced into both diaphragm chambers, the intake valve 14 is in the fully open position and the diaphragm chamber 18 is in the fully open position.
When negative pressure is introduced only into the diaphragm chamber, the intake valve 14 is driven to the middle open position, and when negative pressure is introduced into both diaphragm chambers, the intake valve 14 is driven to the fully open position. Diaphragm chamber 18 is connected to port A of negative pressure switching valve 23 via conduit 20, negative pressure delay valve 21, and conduit 22, and diaphragm chamber 19 is connected to port A of another negative pressure switching valve 25 via conduit 24. Connected to A. Negative pressure switching valves 23 and 25 have a port B connected to a negative pressure tank 27 through a conduit 26 and an atmosphere release port C opened to the atmosphere, and when energized, port A is connected to port C. When power is not supplied, port A is connected to port B instead of port C. The negative pressure tank 27 is connected to a negative pressure pump (not shown) through a conduit 28, from which negative pressure is supplied and stored.

The negative pressure switching valve 23 switches the current supplied from the battery power supply 29 to the key switch 30 of the diesel engine 1.
It is designed to be selectively supplied through a series circuit with a normally closed relay switch 31 and a normally closed relay switch 31. The relay switch 31 opens when the accelerator switch 32 is closed and closes when the accelerator switch 32 is open, and the accelerator switch 32 opens only when the accelerator pedal is not depressed at all. engine 1
It is designed to close only when the is operated without load. Current supplied from a battery power source 29 is selectively supplied to the negative pressure switching valve 25 via a key switch 30.

Further, in FIG. 2, numeral 35 is a fuel cutoff valve (not shown) provided in the middle of the fuel discharge passage of a well-known fuel injection valve. The valve is opened only when the power is not energized, and the valve is closed when the power is not energized to close the fuel discharge passage. Current supplied from a battery power source 29 is selectively supplied to the fuel cutoff valve 35 through a series circuit of a key switch 30 and a normally closed relay switch 34. The relay switch 34 is supplied with the current supplied by the battery power supply 29 via the key switch 30 and the delay circuit 33.
Even if the key switch 30 is opened, a predetermined period of time t
The energized state is maintained only when (0<t≦2 seconds).

During load operation when the accelerator pedal is depressed while the engine is running, the accelerator switch 32
is open, and at this time key switch 30 is open.
are closed, the negative pressure switching valves 23 and 25
Electricity is applied to both. As a result, atmospheric pressure is introduced into both diaphragm chambers 18 and 19, and the intake valve 1
4 is brought to the fully open position as shown by the solid line in the figure, and there is no intake throttling or intake blocking. Therefore, the intake valve 14 does not impede the drivability of the diesel engine during load operation.

During operation of the diesel engine, during no-load operation when the accelerator pedal is not depressed, the accelerator switch 32 is closed and the relay switch 31 is opened, so that the negative pressure switching valve 25 is energized; is no longer energized,
Therefore, the negative pressure in the negative pressure tank 27 is transferred to the conduit 26, the negative pressure switching valve 23, the conduit 22, the negative pressure delay valve 21, and the conduit 2.
0 into the diaphragm chamber 18, thereby bringing the intake valve 14 to a mid-open position as shown by the imaginary line in the figure, thereby throttling the intake air. This reduces engine vibration and noise during no-load operation.

When the key switch 30 is opened to stop the operation of the diesel engine 1, the negative pressure switching valve 2 is immediately opened.
3 and 25 are no longer energized, and both negative pressure switching valves connect port A to port B instead of port C. Therefore, at this time, the negative pressure stored in the negative pressure tank 27 is introduced into the diaphragm chambers 18 and 19, and the intake valve 14 is immediately brought to the fully closed position as shown by the phantom line in the figure. This causes the intake passage to become blocked. In this way, when the engine is stopped, the intake passage is cut off, so that the amount of intake air to the engine becomes almost zero, and the engine speed rapidly decreases.

After the key switch 30 is opened, the delay circuit 33
When the predetermined time period has elapsed, the relay switch 34 opens, the fuel cutoff valve 35 closes the fuel discharge passage, and the supply of fuel to the diesel engine 1 is stopped. As a result, the diesel engine 1 completely stops without any large vibrations.

FIG. 3 shows the engine vibration level when the diesel engine is stopped. In this graph, the solid line represents the vibration level when the engine is stopped according to the method of the present invention, the dashed line represents the vibration level when the engine is stopped using only the fuel cutoff valve, and the dashed line represents the vibration level when the engine is stopped using only the fuel cutoff valve. A valve and an intake cutoff valve are used, and the vibration levels are shown when both valves are closed at the same time. It will be understood from this graph that the engine can be stopped without causing large engine vibrations according to the stopping method of the present invention.

Although the present invention has been described in detail with respect to specific embodiments above, it will be appreciated by those skilled in the art that the present invention is not limited thereto and that various embodiments can be made within the scope of the present invention. It should be obvious.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing one embodiment of a diesel engine equipped with a device for carrying out the stopping method according to the present invention, and FIG. 2 is a schematic configuration diagram showing one embodiment of the main parts of the device. FIG. 3 is a graph showing the vibration level when stopped. 1... Diesel engine, 2... Cylinder bore,
3...Piston, 4...Combustion chamber, 5...Swirl chamber, 6...Fuel injection nozzle, 7...Intake tube, 8...Valve housing, 9...Intake manifold, 10...Exhaust port, 11...Exhaust manifold, 12...Poppet valve, 13...Valve stem, 14...Intake valve, 15...Lever,
16...Diaphragm device, 17...Rod, 18,
19... Diaphragm chamber, 20... Conduit, 21... Negative pressure delay valve, 22... Conduit, 23... Negative pressure switching valve, 24...
Conduit, 25... Negative pressure switching valve, 26... Conduit, 27... Negative pressure tank, 28... Conduit, 29... Battery power supply, 3
0...Key switch, 31...Relay switch, 32
...Accelerator switch, 33...Delay circuit, 34...Relay switch, 35...Fuel cutoff valve.

Claims (1)

[Claims] 1. A diesel engine having an intake cutoff valve provided in the middle of an intake passage to selectively close the intake passage, and a fuel supply stop means provided in the middle of the fuel passage to selectively stop the fuel supply to the fuel injection nozzle. A method for stopping a diesel engine, characterized in that the intake cutoff valve is closed prior to stopping the fuel supply by the fuel supply stopping means.