JPH0226047B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake device for improving output in a high load range and quietness during idling in a diesel engine.

[Conventional technology]

Generally, among the noises in diesel engines,
The noise generated during idling operation with the accelerator pedal not depressed is significantly higher than the noise generated during idling operation of a spark ignition internal combustion engine.

Therefore, in order to solve this problem, in recent diesel engines, for example,
-As described in Publication No. 8231, etc., there is a structure in the intake path from the air cleaner to each cylinder that is related to the accelerator pedal and closes when the accelerator pedal is stopped and opens wide when the accelerator pedal is depressed. It has been proposed to provide an intake throttle valve. That is, during idling operation with the accelerator pedal stopped being depressed, the intake throttle valve closes and throttles the intake air, which reduces the compression pressure in each cylinder, reduces the angular velocity during the compression stroke, and reduces the maximum angular velocity during the explosion stroke. As the pressure decreases, the rotational force becomes smaller and the rate of accelerating the angular velocity decreases, and the fluctuations in the angular velocity of the crankshaft during the compression and explosion strokes become smaller.
Vibration during engine idling can be reduced. Furthermore, a suitable intake throttle can increase the temperature of the intake air at the end of compression, thereby reducing the ignition delay and reducing combustion noise during idling operation.

[Problem to be solved by the invention]

However, in a diesel engine in which an intake throttle valve related to the accelerator pedal is installed in the intake path from the air cleaner to each cylinder, the intake throttle valve is closed during deceleration when the foot is suddenly removed from the depressed accelerator pedal. It will also be closed in
In other words, when decelerating the diesel engine,
Even though the rotational speed of the diesel engine is quite high, the intake air is suddenly throttled by the closing operation of the intake throttle valve, the actual compression ratio decreases, and the temperature at the end of compression of the intake air decreases. This not only delays combustion and produces smoke such as white smoke or black smoke, but also causes ignition to become unstable, which causes vibrations and combustion noise to increase, rather than when the intake throttle is not used. .

In addition, in recent diesel engines, a surge tank with an appropriate volume is installed in the intake system to each cylinder, and the intake air is distributed from the surge tank to each cylinder separately. In addition to reducing intake noise caused by intake pulsation, a method has been adopted to improve engine output through the effect of inertial intake from a surge tank to each cylinder.In this case, the internal volume and shape of the surge tank is set according to the conditions in the high-load operating range, so it has little effect on reducing intake pulsation noise during idling.

By applying the surge tank to a diesel engine, the present invention aims to reduce intake noise in a high-load operating range and improve output. and prevent combustion noise from increasing,
The purpose is to reduce intake noise in the idling operating range.

[Means to solve the problem]

In order to achieve this object, the present invention provides an intake throttle that is connected to the accelerator pedal in the intake path from the air cleaner to each cylinder, and that closes when the accelerator pedal is stopped and opens wide when the accelerator pedal is depressed. In a diesel engine provided with a valve, a surge tank is provided in the intake path downstream of the intake throttle valve, and is connected to each cylinder via an intake passage; The hot air introduction passage from the hot air generation source is connected to a portion downstream of the intake throttle valve so as to be in continuous communication with the hot air introduction passage, and a throttle orifice for regulating the flow rate is provided in the hot air introduction passage. did.

[Action/effect of the invention]

In this way, by providing a surge tank connected to each cylinder via the intake passage in the intake path downstream of the intake throttle valve from the air cleaner to each cylinder, the surge tank is installed in the intake path from the air cleaner to each cylinder. In addition to reducing intake noise in the engine, engine output in high-load operating ranges can be improved by inertial intake.

On the other hand, by connecting a hot air introduction passage with a throttle valve from a warm air generation source to a portion of the intake path downstream of the intake throttle valve so as to be in constant communication with the hot air intake path, the accelerator pedal can be stopped from being depressed. When the intake throttle valve closes during idling operation, the intake negative pressure on the downstream side of the intake throttle valve increases toward the vacuum side, so that warm air heated at the warm air generation source is supplied to each cylinder. , is inhaled through the warm air introduction passage.

In this case, the intake negative pressure on the downstream side of the intake throttle valve is moved closer to the vacuum side by the intake throttle valve closing suddenly when decelerating when the foot is suddenly removed from the accelerator pedal. Therefore, the amount of warm air taken in through the warm air introduction passage increases due to the sudden closing of the intake throttle valve.

Therefore, by sucking in this warm air, it is possible to prevent the temperature of the intake air at the end of compression from decreasing due to a decrease in the actual compression ratio due to the sudden closing of the intake throttle valve. The increase in vibration and combustion noise as well as the generation of smoke caused by the sudden closing of the engine can be reliably reduced by an extremely simple configuration in which a warm air introduction passage is connected to the intake passage.

In addition, when the intake throttle valve is closed, the amount of warm air taken in through the warm air introduction passage is controlled by a flow rate regulating orifice provided in the warm air introduction passage. This makes it possible to accurately control vibrations, noise, and smoke generated during deceleration without impairing the effect of the throttle so as to reliably reduce them.

Additionally, the intake passages to the surge tank and each cylinder are generally designed to reduce intake inertia and intake pulsation in the high negative range. With this intake passage, it is not possible to reduce intake pulsation in the idling operating range.

In contrast, in the present invention, the surge tank is located downstream of the intake throttle valve, in other words, the intake throttle valve is closed in the idling operating range when the accelerator pedal is not depressed.
By being located upstream of the surge tank, the intake throttle valve can prevent intake noise caused by intake pulsation in the idling operating range from propagating into the atmosphere via the upstream air cleaner. This makes it possible to reduce intake noise in the idling range.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a diesel engine equipped with a plurality of cylinders, and reference numeral 2 indicates the diesel engine 1.
3 is a foot-operated accelerator pedal, and 4 is a control lever for adjusting the fuel injection amount in the fuel injection pump 2, and the control lever 4 is connected to a wire. The output of the diesel engine 1 is adjusted by increasing or decreasing the amount of fuel injected when the accelerator pedal 3 is depressed.

Further, reference numeral 5 indicates an intake manifold for the diesel engine 1, and reference numeral 6 indicates an exhaust manifold for the diesel engine 1. The internal volume of the surge tank 7 and the inner diameter and length of each intake passage 8 are determined by the above-mentioned diesel engine. In the operating range where the load is high in No. 1, the effect of inertial intake can be obtained and the intake pulsation noise is reduced (this is conventionally known).

A butterfly-type intake throttle valve 12 is provided in the main intake passage 10 that connects the surge tank 7 and the air cleaner 9 to open and close the intake passage 10 by rotating the valve shaft 11. A lever 13 fixed to the valve shaft 11 of the throttle valve 12 is connected to a rod 16 attached to a diaphragm 15 in a diaphragm drive device 14, and a spring 18 in a diaphragm chamber 17 keeps the intake throttle valve 12 fully open at all times. The diaphragm chamber 17 in this diaphragm drive device 14
An electromagnetic three-way switching valve 21 is provided in a passage 20 connecting the vacuum pump 19 and the vacuum pump 19 driven by the diesel engine 1.

This three-way switching valve 21 has an electromagnetic solenoid 2
When the electromagnetic solenoid 22 is not energized, the passage 23 to the atmosphere is blocked and the diaphragm chamber 17 and the vacuum pump 19 are communicated with each other, but when the electromagnetic solenoid 22 is energized, the atmosphere passage 23 is communicated with the diaphragm chamber 17. In the electric circuit 25 connecting the electromagnetic solenoid 22 and the battery 24, there is a control lever 4 in the fuel injection pump 2 which is turned off when the accelerator pedal 3 is stopped. A switch 26 is provided so that the electromagnetic solenoid 22 in the three-way switching valve 21 is not energized, and when the accelerator pedal 3 is depressed, it is turned on to energize the electromagnetic solenoid 22 in the three-way switching valve 21.

Further, in the main intake passage 10, a warm air intake hole 27 is provided at a downstream side of the intake throttle valve 12.
The warm air intake hole 27 is provided so as to be always open.
and a warm air generation source such as a heat protector 28 provided for the exhaust manifold 6,
The intake throttle valve 1 communicates with the intake throttle valve 1 through a hot air introduction passage 30 equipped with a throttle orifice 29 for regulating the flow rate.
The heat protector 28 is configured so that when the pressure on the downstream side of the heat protector 2 becomes a vacuum side by closing the intake throttle valve 12, the warm air inside the heat protector 28 is sucked.

In this configuration, in an operating range other than idling with the accelerator pedal 3 depressed, the switch 26 in the electric circuit 25 is turned on, the electromagnetic solenoid 22 of the three-way switching valve 21 is operated, and the three-way switching valve 21 is a diaphragm type. Since the diaphragm chamber 17 of the drive device 14 is switched to communicate with the atmosphere, the intake throttle valve 12 is fully opened by the spring 18, and the intake throttle valve 12 does not control the regulation of intake air to the engine. The amount of intake air increases due to the effect of inertial intake by the surge tank 7 and the intake passages 8 to each cylinder, and the output of the engine increases. The intake pulsation noise is reduced.

In the idling operating range with the accelerator pedal 3 no longer depressed, the switch 26 in the electric circuit 25 is turned off, and the three-way selector valve 21 is turned off.
However, the diaphragm chamber 17 is connected to the vacuum pump 19.
The diaphragm chamber 17
Due to the vacuum acting on the intake throttle valve 12
is in the closed state against the spring 18, so the amount of intake air from the air cleaner 9 to each cylinder is regulated. Since the negative pressure is large on the vacuum side, warm air warmed within the heat protector 28 is drawn into each cylinder via the warm air introduction passage 30 with the flow rate regulating orifice 29.

In this case, the intake negative pressure on the downstream side due to the intake throttle valve 12 increases toward the vacuum side as the intake throttle valve 12 is closed more rapidly, so the amount of warm air taken in through the warm air introduction passage 30 increases. , increases due to the sudden closing of the intake throttle valve 12.

The closed position of the intake throttle valve 12 in the idling driving range when the accelerator pedal is no longer depressed is as follows:
The stopper is set so that the intake negative pressure on the downstream side of the intake throttle valve 12 is about -50 to -200 mmHg.
(not shown) is preferable because it allows the engine to smoothly transition from load operation to idling, and from idling to load operation.

In idling operation with the accelerator pedal stopped being depressed, the surge tank 7 and the intake passage 8 for each cylinder do not match the reduction of intake pulsation, and the surge tank 7 and the intake passage 8 for each cylinder do not match the intake pulsation reduction. Although intake pulsation cannot be expected to be reduced, if the intake throttle valve 12 is provided upstream of the surge tank 7 and closes in the idling range when the accelerator pedal is no longer depressed, as in the present invention, the surge tank The intake throttle valve 12 can prevent intake noise caused by the intake pulsation in the intake throttle valve 7 from propagating upstream.

In the above embodiment, the intake throttle valve 12 was provided between the air cleaner 9 and the surge tank 7, but the air cleaner 9 is installed between the intake throttle valve 12 and the surge tank as shown by the two-dot chain line. 7, the intake throttle valve 12 may be configured to be located on the upstream side of the air cleaner 9, and the intake throttle valve 12 may be configured to be located upstream of the air cleaner 9. Furthermore, the heat source for preheating the intake air is not limited to the exhaust manifold of the embodiment.
It goes without saying that other heat sources can be used, such as cooling water or lubricating oil for the engine.

[Brief explanation of drawings]

The drawings are diagrams showing embodiments of the invention. 1... Diesel engine, 2... Fuel injection pump, 3... Accelerator pedal, 5... Intake manifold, 6... Exhaust manifold, 7... Surge tank, 8... Intake passage, 9... Air cleaner, 1
0... Main intake passage, 12... Intake throttle valve, 1
4... Diaphragm type drive device, 19... Vacuum pump, 21... Three-way switching valve, 28... Heat protector as a warm air generation source, 30...
...Hot air introduction passage.

Claims (1)

[Claims] 1. In a diesel engine that is provided with an intake throttle valve in the intake path from the air cleaner to each cylinder, which is connected to the accelerator pedal and closes when the accelerator pedal is stopped and opens wide when the accelerator pedal is depressed, In the intake path, a portion downstream of the intake throttle valve,
A surge tank connected to each cylinder via an intake passage is provided, and a warm air introduction passage from a warm air generation source is constantly connected to the intake passage downstream of the intake throttle valve. What is claimed is: 1. An intake device for a diesel engine, characterized in that the hot air introduction passage is connected to the hot air intake passage, and a restrictor orifice for regulating the flow rate is provided in the hot air introduction passage.