JPS58165550A - Vibration reducer for diesel engine - Google Patents

Abstract

PURPOSE:To suppress the generation of exhaust smoke through a vibration reducer including an intake air throttle valve for constricting an intake passage in the low speed and load operation of an engine, by providing a by-pass around the throttle valve, installing a restrictor valve in the by-pass and controlling the degree of opening of the latter valve depending on the degree of nontransparency of exhaust gas. CONSTITUTION:A by-pass 16 is provided around an intake air throttle valve 2 installed in the halfway part of an intake passage 1. An electromagnetic restrictor valve 17 is provided in the by-pass 16. This minimum degree of opening of the valve 17 is predetermined so that a prescribed quantity of intake air is introduced through between the body 18 of the valve and the wall surface of the by-pass 16. Photoelectric elements 20, 21 are provided in the halfway part of an exhaust passage 14 to detect the degree of nontransparency of exhaust gas downstream to a muffler 19. The output of the light receiving element 21 is applied to a smoke quantity discrimination circuit 31 through a power amplifier 30. When the circuit 31 has judged that the degree of nontransparency of exhaust gas has exceeded a prescribed level, a solenoid valve 17 is energized through a relay 32 to open the by-pass 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reducing engine vibration in a low speed, low load range of a diesel engine.

Diesel engines are compression ignited, so the compression ratio is 2 to 3 times higher than spark ignition engines such as gasoline engines, and the work in the compression stroke is extremely large, causing torque fluctuations and rotational speed fluctuations. Especially when the engine is idling, this residual brass becomes noticeable and causes an increase in engine vibration.

(Sankaido (Publishing) Automotive Engineering Complete Book Volume 5 Diesel Engine) Also, when idling, the ambient noise level is low, and the intake noise may cause tinnitus. A device has been proposed that reduces vibration and improves ignition performance by throttling the intake air and heating the intake air under load. (Utility Model Application Publication No. 56-76158) Furthermore, the present applicant has provided the following information in Figs. 1 and 2. As shown in FIG. 2, an improved operation of the intake throttle valve 2 and intake air heating means 10 has been proposed.

This vibration reduction device has 1. For example, a load detection switch 5 responsive to a control lever 4111 degrees of the fuel injection pump 3;
Based on the signal from the rotation sensor, etc. that detects the engine rotation speed from the pump rotation shaft, etc., when the speed is low and the load is low,
A control circuit (not shown) energizes a solenoid 6 that drives the intake throttle valve 2 to fully close the throttle valve 2.

At this time, the intake air is introduced through the small-diameter auxiliary passage 7 that bypasses the comparison valve 2, so that a predetermined amount of intake air, or in other words, a predetermined suction negative pressure downstream thereof, is obtained.

That is, by throttling the intake air, the compression pressure in the combustion chamber is relatively lowered, and the work in the compression stroke is reduced by the reduction in peak pressure. This suppresses rotational speed fluctuations and torque fluctuations, and reduces engine vibration in low-speed, low-load ranges.

Furthermore, since the throttle valve 2 is fully closed, intake noise is attenuated, and noise during idling and the like is reduced. In addition, in the low speed and low load range, the amount of fuel injected from the fuel injection valve 9 is small, and the air-fuel mixture has too much air, so even if the intake air is throttled in this way, the air necessary for combustion will be secured. .

By the way, when the compression pressure is lowered by narrowing down the intake air in this way, the air temperature also decreases, making the ignition of the injected fuel unstable, which tends to cause misfires and asymmetric combustion.

Therefore, in the above device, a sheath heater 1 is provided as a heating means 10 on the downstream side of the throttle valve 2 and the auxiliary passage 7 so as to throttle the intake air and heat the intake air at the same time.

The sheath heater 1 is assembled into a unit, for example, in a throttle chamber 12 in which a throttle valve 2 is interposed, and is energized by a control circuit to heat intake air only when the throttle valve 2 is, in principle, fully closed.

In this case, a combustion chamber glow plug (not shown) may also be used.

This relatively increases the intake air temperature to compensate for the drop in compression pressure and prevent deterioration of the combustion state. Therefore, combustion stability is maintained despite the reduction in compression pressure, and irregular vibrations and torque fluctuations due to irregular combustion are avoided.

In this way, vibration and noise in the idling special low speed and low load range □, 1) are reduced, and driving comfort is improved 1::
1 I am trying. 1'1 [□ ::1:1 However, if the vibration reduction device restricts the intake air to the low speed and low load range to lower the compression pressure in the combustion chamber, the intake air will be heated -4 − Although ignition errors and irregular combustion are avoided and combustion stability is maintained, it is difficult to achieve complete combustion, and depending on the operating conditions, unburned components increase and exhaust smoke is likely to occur. There was a problem.

This invention was made in view of these problems, and detects the occurrence of smoke based on the opacity of the exhaust gas.
It is an object of the present invention to provide a vibration reduction device that solves the above problems by increasing the amount of intake air when the opacity exceeds a predetermined value, thereby increasing the compression pressure and promoting combustion.

Below, this invention will be explained based on the drawings. FIG. 3 is a diagram showing an embodiment of the present invention, and 13 is an engine main body;
1 is an intake passage, and 14 is an exhaust passage.

In the middle of the intake passage 1, a butterfly-type intake throttle valve 2 is installed in a throttle chamber 12 so as to be freely rotatable via a valve shaft 15. When a solenoid (not shown) that drives the check valve 2 is energized, the check valve 2 is completely closed.

When the valve is fully closed, a bypass passage 16 is formed that bypasses the comparison valve 2 and guides the intake air, and a valve (for example, a solenoid valve) 17 that opens and closes the bypass passage 16 is installed in the middle of the bypass passage 16 .

This solenoid valve 17 is connected to a bypass passage 16 during excitation, which will be described later.
is opened, and the bypass passage 16 is closed when released.

In this case, even if the solenoid valve 17 is closed, the valve body 1 of the solenoid valve 17
The minimum opening degree of the electromagnetic valve 17 is set so that a predetermined amount of intake air is introduced from between the side of the solenoid valve 8 and the bypass passage 161.

As a result, when the throttle valve 2 is fully opened at low speed and low load of the engine, a predetermined suction negative pressure is secured downstream without cutting off the intake air, lowering the compression pressure in the combustion chamber and reducing engine vibration. .

Note that an intake air heating means (not shown) that heats the intake air at the same time as the throttle valve 2 is fully closed is disposed downstream of these.

On the other hand, -6 of the muffler 19 is located in the middle of the exhaust passage 14.
- A light emitting diode 20 that emits light from the side of the exhaust passage 14 into the exhaust gas as a means for detecting opacity in the exhaust gas on the downstream side, and a light emitting diode 20 located on the opposite side of the light emitting diode 20 to sense the brightness of the light. A phototransistor 21 is provided.

Specifically, as shown in FIGS. 4 to 6, the light emitting diode 20 and the phototransistor 21 are fixed between a support 23 and a cap 24, each having a through hole 22 therein. The support 23 is attached by screwing into a mount 25 formed on the opposite side of the exhaust passage 14.

In this case, a cap 26 fitted with, for example, a glass plate is attached to the tip of the support 23 to prevent the light emitting diode 20 and the phototransistor 21 from being directly exposed to exhaust air.

1□□ Also, in order to prevent soot from the exhaust air from adhering to one side of the quartz glass and causing it to become cloudy, electric heating I! is applied between the quartz glass and the tip of the support 23. 27 is installed and heated at appropriate times to purify the soot.

-7- This heating wire 27 is energized by the battery 28, but
It is desirable that the heating is performed at all times at least when the engine is running at low speeds and under low load.

The light emitting diode 20 is also energized by the battery 29 and emits light, but it may be configured to operate only at low speeds and low loads, for example, in conjunction with the solenoid.

On the other hand, the phototransistor 21 is a light emitting diode 20
It receives light from the outside and outputs a signal according to its brightness.

This signal is amplified via the power amplifier 3o and then sent to the smoke amount determination circuit 31.

Here, if the opacity in the exhaust gas is high, the Q@ from the phototransistor 21 becomes small, that is, the state of smoke generation is detected.

Then, in the smoke amount determination circuit 31, if the opacity of the exhaust gas exceeds a predetermined value based on the signal, the relay 32
Activate □, and energize the solenoid valve 17.

command to open the Pampas passage 16. This results in
I'm trying to increase my intake.

With this configuration, the throttle valve 2 is fully opened - 8
- When the engine is running at low speed and with a low load, the minimum opening of the solenoid valve 17 allows a predetermined amount of intake air to be introduced from the bypass passage 16, and engine vibration and noise are reduced by heating the intake air while maintaining combustion stability.

On the other hand, when the operating conditions change, for example when the load increases to a certain extent (at low speed and low load), the combustion state deteriorates slightly due to the low pressure in the combustion chamber, making it easier to generate exhaust smoke.

When the amount of smoke generation exceeds a predetermined value, the opacity of the exhaust increases, and the phototransistor 21 detects the smoke amount determination circuit 3.
The signal input to °1 becomes smaller.

Then, when the opacity of the exhaust exceeds a predetermined value, the smoke determination circuit 31 activates the relay 32 and opens the solenoid valve 17 of the bypass passage 16.

Therefore, a large amount of intake air is introduced, and the compression pressure in the combustion chamber is increased. However, -), the intake air temperature rises,
Combustion becomes more stable, the combustion rate becomes faster, and it is sufficiently promoted.

As a result, almost complete combustion can be achieved and the generation of smoke can be suppressed. In this embodiment, -9- reduces engine vibration etc. in this way, and
The system detects smoke in the exhaust, and if smoke exceeds a predetermined level, the amount of intake air is increased to promote combustion, maintain a good combustion state, and improve the exhaust composition.

As explained above, according to the present invention, in a diesel engine that is provided with an intake throttle valve that throttles the intake passage when the engine is running at low speed and under low load, and a means that also heats the intake air, vibration and noise are reduced. Directing the intake air by bypassing the intake throttle valve (forming a bypass passage, and providing means for detecting opacity in the exhaust air in the middle of the exhaust passage,
Since a valve is provided that opens the bypass passage only when the opacity exceeds a predetermined value in response to the signal from the detection means, engine vibration etc. can be sufficiently reduced, and good combustion can always be obtained. This has the effect of suppressing the generation of smoke.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the structure of a conventional device proposed earlier by the present applicant, Fig. 2 is a front view thereof, Fig. 3 is a sectional view of the main part structure showing an embodiment of the present invention. 5 is a partially exploded sectional view thereof, FIG. 5 is a view taken along line A--A in FIG. 4, and FIG. 6 is a partial sectional view of FIG. 3. DESCRIPTION OF SYMBOLS 1... Intake passage, 2... Intake throttle valve, 5... Load detection switch, 6... Solenoid, 10... Heating means, 14... Exhaust passage, 16... Bypass passage, 1
7...Valve, 20...Light emitting diode, 21...Phototransistor, 31...Smoke amount determination circuit. Patent applicant Nissan Motor Co., Ltd. -11-

Claims (1)

[Claims] Same as the intake throttle valve that throttles the intake passage when the engine is running at low speeds and under low load. 1. A vibration reduction device for a diesel engine, comprising: detecting means; and a valve that opens the bypass passage only when opacity exceeds a predetermined value in response to a signal from the detecting means.