JPS635568B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for an automobile diesel engine.

Generally, unlike gasoline engines, diesel engines do not have a so-called throttle valve in the intake passage, so during light loads, especially when idling, the amount of intake air becomes excessive, which increases engine compression resistance and torque. Fluctuations are likely to occur.

Therefore, there is a problem in that the engine vibrates due to this torque fluctuation and generates vibration noise.

As a method to solve this problem, an intake shutter is installed in the intake passage so that it can be opened and closed, and when the accelerator pedal is released, the intake shutter is closed and the intake passage is narrowed, reducing the amount of intake air and causing vibrations in the engine. It is known to use an intake shutter device that aims to reduce the amount of air and vibration noise.

However, in such an intake shutter device, when the key switch is opened, the intake shutter is normally fully opened, while the fuel passage of the injection pump is closed. As a result, a large amount of air flows into the combustion chamber, increasing the compression resistance of the engine.
The engine, which normally stops operating gradually due to the inertial rotation of the flywheel, is brought to a sudden stop, and there is also the disadvantage that the driver and other passengers receive a large shock, a so-called key-off shock.

The present invention has been made in view of the above-described problems, and provides an intake system for a diesel engine as described above, which eliminates the above-mentioned drawbacks by configuring the intake shutter to close when the key switch is opened. The purpose is to provide.

The present invention is characterized in that when the key switch is opened, the actuator is operated in response to a signal from the key switch to close the intake shutter and throttle the amount of intake air, and at the same time close the fuel passage of the fuel injection pump.

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 In FIG. 1, 1 is an engine, and 2 and 3 are an intake passage and an exhaust passage that communicate with the combustion chamber of the engine 1, respectively.

Reference numeral 4 denotes an intake shutter composed of a butterfly valve, which is attached to the intake passage 2 so as to be openable and closable.

This intake shutter 4 is connected to a power chamber 6 as an actuator via a link mechanism 5, and is held in the open position (see solid line in Figure 1) when the negative pressure chamber 6a of the power chamber 6 is in an atmospheric state. On the other hand, the negative pressure chamber 6a of the power chamber 6
When the diaphragm 6b is in a negative pressure state, the diaphragm 6b is deviated against the elastic force of the spring 6c to be in the closed position (see the dashed line in FIG. 1).

A negative pressure chamber 6a of the power chamber 6 is connected to a vacuum tank 9 through a negative pressure passage 8 in which a three-way solenoid valve 7 is interposed. A vacuum pump 10 driven by the engine 1 is connected to the vacuum tank 9 via a check valve 11.

The three-way solenoid valve 7 opens the negative pressure passage 8 when the excitation coil 7a is not excited and is not energized, and connects the negative pressure chamber 6a of the power chamber 6 to the vacuum tank 9.
When the excitation coil 7a is energized and energized, the negative pressure chamber 6a is opened to the atmosphere through the atmospheric hole 7b.

Reference numeral 12 denotes a battery with one end grounded.A key switch 13, which is closed when the engine 1 is operated, is connected in series to the battery 12.A cooler switch 14, which is closed when the cooler is activated, and an accelerator pedal (not shown) are connected in series to the battery 12. An accelerator switch 15 that closes when the switch (omitted) is pressed and opens when released is connected in parallel. Further, one terminal of the excitation coil 7a of the three-way solenoid valve 7 is connected to the cooler switch 14 and the accelerator switch 15, and the other terminal is grounded.

16 is a distribution type fuel injection pump, and its control lever 16a is an accelerator pedal (not shown)
The amount of fuel to be injected is determined by the amount of depression of the accelerator pedal and the engine speed. 17 is an air cleaner.

Note that when the key switch 13 is closed, the fuel passage of the fuel injection pump 16 is opened, while when the key switch 13 is opened, the fuel passage is closed and the engine 1 is stopped.

According to the above configuration, during idling operation such as warm-up operation of the engine 1, since the accelerator pedal is released, the accelerator switch 15 is opened (the key switch 13 is, of course, closed).

By opening the accelerator switch 15, the excitation coil 7a of the three-way solenoid valve 7 and the battery 12
The electrical connection with the three-way solenoid valve 7 is cut off.
opens. As a result, negative pressure is introduced from the vacuum tank 9 into the negative pressure chamber 6a of the power chamber 6 through the negative pressure passage 8, and the intake shutter 4 is operated to close by the diaphragm 6b via the link mechanism 5, as shown in FIG. is in the closed position as shown by the dashed line.

The amount of restriction of the intake shutter device in this closed position is 100 mmHg or more and 400 mmHg or less (preferably 150 mmHg or less).
mmHg to 350mmHg) to suppress engine vibration and noise that occur during idling. Here, the throttle amount of the intake shutter device is set when the engine is idling, that is, when the engine is running at 600 r.p.
It is expressed by the intake negative pressure downstream of the intake shutter when rotating at a speed of m.m, and it has been confirmed through experiments that it is desirable to be within the above range.

Furthermore, when the car cooler is activated to apply a load to the engine 1, the cooler switch 14 is closed and the excitation coil 7a of the three-way solenoid valve 7 is energized to close the three-way solenoid valve 7, so that the negative pressure chamber 6a of the power chamber 6 is closed. is opened to the atmosphere through the air hole 7b, and as a result, the intake shutter 4 is
It is in the open position as shown by the solid line in the figure.

Then, as the load on the engine 1 increases, the amount of intake air increases, resulting in a good combustion state without causing half-misfire.

In addition, during normal operation with the accelerator pedal depressed, the accelerator switch 15 is closed, so the three-way solenoid valve 7 is energized and closed, blocking the negative pressure passage 8 and blocking the negative pressure chamber of the power chamber 6. 6a is communicated with the atmosphere through an atmospheric hole 7b. Thereby, the intake shutter 4 is kept in the open position.

Next, when the key switch 13 is opened to stop the engine 1, the excitation coil 7a of the three-way solenoid valve 7 is de-energized, the three-way solenoid valve 7 is opened, and vacuum is supplied to the negative pressure chamber 6a of the power chamber 6. The tank 9 is brought into communication.

As a result, after the key switch 13 is opened, the intake shutter 4 is held in the closed position (at this time, the fuel passage of the fuel injection pump 16 is closed) until the negative pressure in the vacuum tank 9 is consumed. 1 stops smoothly.

The accelerator switch 15 does not necessarily need to be of a type that directly responds to the movement of the accelerator pedal, but may be of a type that indirectly senses movement. For example, a switch that detects the position of the control lever 16a of the fuel injection pump 16 can be used.

Embodiment 2 In FIG. 2, a three-way solenoid valve 21 installed in a negative pressure passage 8 opens the negative pressure passage 8 and closes the negative pressure chamber 6a of the power chamber 6 when the excitation coil 21a is energized. It communicates with the Yum tank 9, and is configured to open the negative pressure chamber 6a to the atmosphere through the air hole 21b when the excitation coil 21a is not energized and is not energized.

Reference numeral 22 denotes a bypass passage in which a solenoid valve 23 is interposed, which connects the upstream side and the downstream side of the intake shutter 4 of the intake passage 2.

One end of the battery 12 is grounded, and the other end of the battery 12 branches, and one end is connected to a key switch 13 and an accelerator switch 24, which opens when the accelerator pedal is pressed and closes when the accelerator pedal is released, and the other end connects to a relay switch 2.
5 to first and second input terminals 26a and 26b of a two-stage relay switch 26, respectively. An output terminal 26c of the relay switch 26 is connected to the other end of the excitation coil 21a of the three-way solenoid valve 21, one end of which is grounded.

This two-stage changeover type relay switch 26 operates so that the excitation coil 2 is closed while the key switch 13 is closed.
6d is excited and the first input terminal 21a and output terminal 2
6c, when the key switch 13 is open, the excitation coil 26d is de-energized, so the second input terminal 26b and the output terminal 26c are switched.
It is configured to connect with.

27 is a transistor whose base B is connected between the key switch 13 and the accelerator switch 24, and also connected to a capacitor 28 whose one end is grounded. Further, the collector C of the transistor 27 is connected to the excitation coil 25a of the relay switch 25, and the emitter E is grounded.

29 is a cooler switch, one terminal of which is connected to the excitation coil 23a of the electromagnetic valve 23 whose one end is grounded, while the other terminal is connected between the key switch 13 and the accelerator switch 24 and the excitation coil 26d of the relay switch 26. electrically connected to.

In the description of this example, the same reference numerals are used for the same components as those of Example 1, and detailed description thereof is omitted.

According to the configuration of this example, the accelerator switch 24 is closed during idling when the accelerator pedal is released. At this time, normally solenoid valve 2
3 is closed, the bypass passage 22 remains closed.

By closing the accelerator switch 24, the three-way solenoid valve 21 is energized and opened, negative pressure is introduced into the negative pressure chamber 6a of the power chamber 6, and the intake shutter 4 is rotated to the closed position. Note that the throttle amount of the intake shutter device in this closed position is set to 100 mmHg or more and 400 mmHg or less (preferably 150 to 350 mmHg), as in the first embodiment.

When the car cooler is activated, the cooler switch 29
When the solenoid valve 23 is closed, the solenoid valve 23 is energized and opened.
The bypass passage 22 is opened to increase the substantial passage cross-sectional area of the intake passage 2. Therefore, the amount of throttle of the intake shutter device is reduced, and the same effect as in the first embodiment when the intake shutter 4 is kept in the open position is obtained.

When the engine is stopped, the key switch 13 is opened and at the same time, the relay switch 26 is switched, and the first input terminal 26a is switched to the second input terminal 26b. On the other hand, due to the discharge of the charge stored in the capacitor 28, a current flows to the base B of the transistor 27, making the transistor 27 conductive.As a result, current flows from the battery 12 to the excitation coil 25a of the relay switch 25, and the relay switch 25 is closed. As a result, current is also supplied from the battery 12 to the excitation coil 21a of the three-way solenoid valve 21, and as the three-way solenoid valve 21 opens, the negative pressure stored in the vacuum tank 9 is released from the negative side of the power chamber 6. is introduced into the pressure chamber 6a, and the key switch 1
Even after the intake shutter 3 is opened, the intake shutter 4 is kept in the closed position for a while (at this time, the fuel passage of the fuel injection pump 16 is closed).

Therefore, the inertial rotation of the flywheel is not disturbed, and the engine quietly stops a short time after the key switch is opened.

In the present invention, after the key switch is opened, the actuator is actuated in response to a signal from the key switch to close the intake shutter and throttle the amount of intake air, and at the same time close the fuel passage of the fuel injection pump. The amount of air is suppressed, the compression resistance of the engine rotating due to inertia does not become so large, and the occurrence of so-called key-off shock after the key switch is opened can be prevented. In addition, since the intake throttle and fuel cut are used together, the structure is simple, there is no need to increase the precision of intake shutters to prevent jamming, and the discharge of unburned gas due to misfire when the key switch is opened is eliminated. It can be prevented.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIG. 1 is an overall configuration diagram of an intake system for a diesel engine according to a first embodiment, and FIG. 2 is an overall configuration diagram of the same according to a second embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 3... Exhaust passage, 4... Intake shutter, 5... Link mechanism, 6... Power chamber, 6a... Negative pressure chamber,
6b...Diaphragm, 6c...Spring, 7
... Three-way solenoid valve, 7a ... Excitation coil, 7
b... Atmospheric hole, 8... Negative pressure passage, 9... Vacuum tank, 10... Vacuum pump, 11... Check valve, 12... Battery, 13... Key switch, 14... Cooler switch, 15... ...Accelerator switch, 16...Fuel injection pump, 16a...
... Control lever, 17 ... Air cleaner, 21 ... Three-way solenoid valve, 21a ... Excitation coil, 21b ... Air hole, 22 ... Bypass passage, 23 ... Solenoid valve, 23a ... Excitation coil, 2
4... Accelerator switch, 25... Relay switch, 25a... Excitation coil, 26... Relay switch, 26a... First input terminal, 26b... Second
Input terminal, 26c... Output terminal, 26d... Excitation coil, 27... Transistor, 28... Capacitor, 29... Cooler switch.

Claims (1)

[Scope of Claims] 1. Load detection means for detecting a light load condition, wherein an intake shutter is provided in the intake passage to allow a predetermined amount of intake air to pass through when the intake passage is closed, and an actuator is provided to drive the intake shutter to open and close. In the intake system of a diesel engine equipped with an intake shutter device that closes the intake shutter in response to a signal from the key switch and throttles the amount of intake air during light loads, when the key switch is opened, the actuator is actuated in response to the signal from the key switch to reduce intake air. An intake system for an automobile diesel engine, characterized in that the shutter is closed to throttle the amount of intake air, and at the same time the fuel passage of a fuel injection pump is closed. 2. The intake shutter device includes a power chamber that is an actuator that closes the intake shutter;
It has a vacuum tank and a negative pressure passage connecting the vacuum tank and the negative pressure chamber of the power chamber, and a three-way solenoid valve is interposed in the negative pressure passage, and the three-way solenoid valve is connected to the key switch. An intake device for an automobile diesel engine according to claim 1, which opens when opened. 3 A three-way solenoid valve opens when energized.
3. The intake system for an automotive diesel engine as claimed in claim 2, further comprising a circuit that connects the three-way solenoid valve to a battery for a predetermined period of time after the key switch is opened to excite the battery.