JPH0361010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake throttle device for a diesel engine.

In diesel engines, the load is generally controlled, in other words, the speed is regulated, by controlling the fuel injection amount without controlling the intake air amount, but the intake air amount is limited during no-load operation (during idling). Then,
It is known that vibration and noise during idle operation are reduced. In view of this, it has been conventionally considered to restrict the amount of intake air by throttling the intake passage with an intake throttle valve when the diesel engine is idling.

The intake throttle amount during idling operation is determined within a range that does not generate white smoke, but if this is determined based on the standard atmospheric pressure on flat ground, it will be , the absolute pressure in the intake passage is lower compared to the level ground, so when the intake air is throttled during idling in the same way as it is on the level ground when driving at high altitude, the absolute pressure in the intake passage becomes excessive. As a result, the compression pressure of the diesel engine decreases, causing incomplete combustion and producing a large amount of white smoke in the exhaust gas.

The present invention provides a diesel engine capable of inhibiting intake throttling during idling operation when the atmospheric pressure drops beyond a certain predetermined value, thereby avoiding the generation of white smoke due to the above-mentioned causes. The primary objective is to provide an intake throttle device.

By the way, when stopping a diesel engine, it is effective to completely block the intake passage to stop the engine quickly and reliably and to prevent abnormal vibrations. Are known. Therefore, the present invention reduces vibration and noise during idling by providing an intake throttle valve in the intake passage of a diesel engine. At the same time, the intake throttle valve is effectively used to block the intake passage when the engine is stopped, and at the same time, the intake throttle valve is effectively used to block the intake passage when the engine is stopped. In the end, to prevent the intake passage from being blocked by the intake throttle valve,
A second object of the present invention is to provide an intake throttle device for a diesel engine that can reliably open an intake passage.

According to the present invention, the above first and second objects include an intake throttle valve provided in the middle of an intake passage;
It has first and second diaphragm chambers, and when both of the first and second diaphragm chambers are open to the atmosphere, the intake throttle valve is fully opened, and the first diaphragm chamber is opened to the atmosphere. When negative pressure is supplied to the second diaphragm chamber, the intake throttle valve is set to an intermediate opening position, and when negative pressure is supplied to both the first and second diaphragm chambers, the intake throttle valve is opened at an intermediate opening. a diaphragm device for fully closing, a negative pressure source, connecting the first diaphragm chamber to the negative pressure source when the key switch is open, and opening the first diaphragm chamber to the atmosphere when the key switch is closed; a first negative pressure switching valve that connects the second diaphragm chamber to the negative pressure source when the key switch is open or when the key switch is closed but the accelerator pedal is not depressed; a second negative pressure switching valve that opens the second diaphragm chamber to the atmosphere when a pedal is depressed; and a second negative pressure switching valve that opens the second diaphragm chamber to the atmosphere when the atmospheric pressure drops below a predetermined value. This is achieved by an air intake throttle device for a diesel engine having an atmosphere release valve that opens a passage that leads negative pressure to the second diaphragm chamber to the atmosphere.

According to the configuration of the intake throttle device for a diesel engine as described above, the operation of throttling the intake passage to an intermediate opening degree during idling operation is performed only when the atmospheric pressure is above a predetermined value, and when the atmospheric pressure is below a predetermined value. When it has decreased, the intake passage is not substantially throttled by the intake throttle valve even during idling operation.
This reliably prevents white smoke from being discharged into the exhaust gas during idling operation in a state where the atmospheric pressure is reduced at high altitudes or the like.

Furthermore, when the engine operation is stopped, both the first and second diaphragm chambers are connected to a negative pressure source at the same time, so that the intake throttle valve is at least temporarily fully closed. This has the effect of completely blocking the air supply passage and stopping the engine quickly and without causing abnormal vibrations. When the engine is restarted, the key switch is closed and at least the first diaphragm chamber is opened to the atmosphere, so that the throttle valve remains open to at least an intermediate opening. Engine starting is virtually unimpeded. The negative pressure source involved in the operation of such an engine may be directly driven by the engine's crankshaft or indirectly driven by the engine by a battery that is charged by the engine. However, the drive is under the control of the engine's key switch, and when the key switch is opened, the drive of the negative pressure source is also stopped. Even in the case of a combination of the above, the negative pressure of the negative pressure source usually disappears when the engine is stopped for a certain period of time. Therefore, according to the above configuration, when the engine is restarted after being stopped for a certain period of time,
Even if the second diaphragm chamber is connected to the negative pressure source by the second negative pressure switching valve when the key switch is closed and the accelerator pedal is not depressed, the second diaphragm chamber is connected to the negative pressure source. No substantial negative pressure acts on the diaphragm chamber, so at this time the intake throttle valve is fully open when the engine is restarted.

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 an intake throttle device 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. diesel engine 1
has a swirl chamber 5 into which liquid fuel for a diesel engine is injected and supplied from a fuel injection nozzle 6.

The diesel engine 1 sucks air into the fuel 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 poppet valves, and only the exhaust poppet valve 12 is shown in the figure.

Mounted on the valve housing 8 is an intake throttle valve 14 of the butterfly valve type carried by a valve stem 13, as best shown in FIG. The intake throttle valve 14 moves between a fully open position as shown by a solid line in the figure, a mid-open position as shown by a phantom line, and a fully closed position as shown by a phantom line. I'm starting to get it. One end of a lever 15 is fixed to the valve shaft 13, and this lever 1
5 is drivingly connected at its other end to a rod 17 of a diaphragm device 16. Diaphragm device 1
6 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 throttle valve 14 is set to the fully open position, and negative pressure is introduced only into the diaphragm chamber 18. When negative pressure is introduced into both diaphragm chambers, the intake throttle valve 14 is driven to the mid-open position (intake throttle position), and when negative pressure is introduced into both diaphragm chambers, the intake throttle valve 14 is driven to the fully closed position (intake cutoff position). It's summery. The diaphragm chamber 18 includes a conduit 20, a negative pressure delay valve 21,
It is connected to port A of the negative pressure switching valve 23 via a conduit 22, and the diaphragm chamber 19 is connected to a conduit 24.
It is connected to port A of another negative pressure switching valve 25 through. Negative pressure switching valves 23 and 25 are connected to conduit 2
6, which are both connected to the negative pressure tank 27 and an atmosphere release port C which is open to the atmosphere, and when energized, port A is connected to port C, and when de-energized, port A is connected to port C. Port B instead
It is now connected to 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 is opened when the accelerator switch 32 is closed and closed when the accelerator switch 32 is open, and the accelerator switch 32 is opened only when the accelerator pedal is not depressed at all. engine 1
It is designed to close only when the engine is idling. A battery power supply 29 is connected to the negative pressure switching valve 25.
The current supplied by the key switch 30 is selectively supplied through the key switch 30.

In addition, the conduit 26 has an atmospheric pressure-sensitive atmosphere release valve 3.
3 is connected. The atmosphere release valve 33 is an aneroid bellows 34 that expands as atmospheric pressure decreases.
, a valve element 36 supported by the aneroid bellows to open and close the valve port 35 , and an atmosphere release port 3
7, and when an atmospheric pressure of a predetermined value or higher is acting on the aneroid bellows 34, the aneroid bellows is in a contracted state and the valve element 3
6 to close the valve port 35 and cut off communication between the conduit 26 and the atmosphere release port 37. On the other hand, when the atmospheric pressure is below a predetermined value, the aneroid bellows 34 extends downward in the figure, and the valve element 36 is pushed down to open the valve port 35, thereby communicating the conduit 26 and the atmosphere release port 37.

When the key switch 30 is closed when starting the engine, the negative pressure switching valve 25 is energized and the port A
is connected to port C. At this time, atmospheric pressure is introduced into the diaphragm chamber 19 of the diaphragm device 16. At this time, if the accelerator pedal is depressed or if the accelerator moves to the open side due to an increase in fuel during the cold period, the accelerator switch 32 will be in the open state, so the negative pressure switching valve 23 will be energized, and the port A is connected to port C. At this time, atmospheric pressure is also introduced into the diaphragm chamber 18 of the diaphragm device 16, and as a result, the intake throttle valve 14
is brought to the fully open position as shown by the solid line in the figure, and does not substantially throttle the intake air.

Furthermore, when the key switch 30 is closed when the engine is started and the accelerator pedal is not depressed, the accelerator switch 32 is closed and the relay switch 31 is opened, and the negative pressure switching valve 23 is not energized, so the port A is The diaphragm 18 is connected to the port B, and if the atmosphere release valve 33 is closed at this time, the diaphragm 18 is connected to the negative pressure tank 27 through a hole. In this case, if the same level of negative pressure remains in the negative pressure tank 27 as during normal operation of the engine, such as when the engine is stopped after being operated for a while and then restarted immediately after, the intake air The throttle valve 14 is brought to an intermediate intake throttle position as shown in phantom in the figure;
Since the air flow rate when starting the engine is as low as during idling, engine startability is not impaired even if the intake throttle valve 14 is in this intermediate position. Furthermore, when the engine is started after a certain period of time has passed after stopping, the negative pressure in the negative pressure tank 27 has disappeared during that time, so the key switch 30 is closed and the accelerator pedal is depressed to start the engine. Even when the diaphragm chamber 18 is connected to the negative pressure tank 27 via ports A and B of the negative pressure control valve 23 when the diaphragm chamber 18 is not in the state where the diaphragm chamber 18 is in a Instead, the intake throttle valve 14 is in the fully open position shown by the solid line.

During load operation when the accelerator pedal is depressed while the engine is running, the accelerator switch 32
is open and both the negative pressure switching valves 23 and 25 are energized, so that both diaphragm chambers 18,
Atmospheric pressure is introduced at 19, and the intake throttle valve 14 is brought to the fully open position as shown by the solid line in the figure, so that the intake throttle valve 14 is not throttled. Therefore, the intake throttle valve 14 does not impede the drivability of the diesel engine during load operation.

When the diesel engine is running at idle, when the accelerator pedal is not depressed, the accelerator switch 32 closes and the relay switch 31 opens, so that the negative pressure switching valve 23 is no longer energized, but the negative pressure switching valve 25 energization is performed.
At this time, if the atmospheric release valve 33 is closed, that is, if the atmospheric pressure is above a predetermined value, the negative pressure tank 27
The negative pressure of the conduit 26, the negative pressure switching valve 23, the conduit 22,
The negative pressure is introduced into the diaphragm chamber 18 via the negative pressure delay valve 21 and the conduit 20, thereby bringing the intake throttle valve 14 to the intake throttle position as shown by the phantom line in the figure to perform intake throttle. . This reduces engine vibration and noise during idle operation.

When the diesel engine 1 is operated at high speed and is decelerated by releasing the accelerator pedal, when the intake throttle valve 14 is brought to the intake throttle position where it immediately throttles the intake air, a negative impact occurs in the intake passage. Although there is a risk that the pressure will increase, in this embodiment, negative pressure is gradually introduced into the diaphragm chamber 18 via the negative pressure delay valve 21, so the intake throttle valve 14 returns to the intake throttle position immediately after deceleration. Therefore, generation of large intake pipe negative pressure in the intake passage is avoided, and the drivability of the diesel engine 1 is not impaired.

On the other hand, if the atmosphere release valve 33 is open,
That is, if the atmospheric pressure is below a predetermined value when driving at high altitudes, even if port A of the negative pressure switching valve 23 is connected to port B, negative pressure will not be introduced into the diaphragm chamber 18, and the intake throttle valve 14 will be fully open. held in position and does not perform any substantial intake throttling.

As mentioned above, when the atmospheric pressure is below a predetermined value, intake throttling is not performed during idling operation, so the absolute pressure in the intake passage is prevented from decreasing excessively, and a large amount of white smoke is produced in the exhaust gas. occurrence is avoided.

When the diesel engine 1 is accelerated by depressing the accelerator pedal from an idling state, the accelerator switch 32 opens, the relay switch 31 closes, the negative pressure switching valve 23 is also energized, and the port A is port B
It will now be connected to port C instead. At this time, atmospheric pressure is immediately introduced into the diaphragm chamber 18 from port C through the throttle passage and check passage of the negative pressure delay valve 21, and the intake throttle valve 14 immediately comes to its fully open position. Therefore, even if the amount of fuel is increased during acceleration, diesel smoke will not occur due to insufficient intake air.

Furthermore, when the key switch 30 is opened to stop the operation of the diesel engine 1, the negative pressure switching valve 23
and 25 are no longer energized, and port A of both negative pressure switching valves is connected 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, thereby bringing the intake throttle valve 14 to the fully closed position as shown by the phantom line in the figure. , the intake passage becomes completely obstructed. In this manner, the intake passage is completely closed when the engine is stopped, thereby reducing engine vibration when the engine is stopped.

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 drawings]

FIG. 1 is a schematic vertical sectional view showing one embodiment of a diesel engine equipped with an intake throttle device according to the present invention, and FIG. 2 is a schematic configuration diagram showing one embodiment of the intake throttle device according to the present invention. DESCRIPTION OF SYMBOLS 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 shaft, 14
...Intake throttle 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, 30... Key switch, 31... Relay switch, 32... Accelerator switch, 33
...Atmospheric release valve, 34...Aneroid bellows,
35... Valve port, 36... Valve element, 37... Atmospheric release port.

Claims (1)

[Claims] 1 An intake throttle valve provided in the middle of the intake passage,
It has first and second diaphragm chambers, and when both of the first and second diaphragm chambers are open to the atmosphere, the intake throttle valve is fully opened, and the first diaphragm chamber is opened to the atmosphere. When negative pressure is supplied to the second diaphragm chamber, the intake throttle valve is set to an intermediate opening position, and when negative pressure is supplied to both the first and second diaphragm chambers, the intake throttle valve is opened at an intermediate opening. a diaphragm device for fully closing, a negative pressure source, connecting the first diaphragm chamber to the negative pressure source when the key switch is open, and opening the first diaphragm chamber to the atmosphere when the key switch is closed; a first negative pressure switching valve that connects the second diaphragm chamber to the negative pressure source when the key switch is open or when the key switch is closed but the accelerator pedal is not depressed; a second negative pressure switching valve that opens the second diaphragm chamber to the atmosphere when a pedal is depressed; and a second negative pressure switching valve that opens the second diaphragm chamber to the atmosphere when the atmospheric pressure drops below a predetermined value. An air intake throttle device for a diesel engine, comprising: an atmosphere release valve that opens a passage that leads negative pressure to the second diaphragm chamber to the atmosphere.