JP2606285Y2 - Swirl control device for diesel engine - Google Patents

Description

[Detailed description of the invention]

[0001]

INVENTION The present invention relates to a relates to the swirl control device for a diesel engine for reducing NO _X emissions at high engine speed region frequently used.

[0002]

2. Description of the Related Art In a diesel engine, the volumetric efficiency with respect to the engine speed is generally relatively high in a middle speed range (especially a speed range of 60 to 80% of a rated speed) as shown in FIG. Since the combustion speed is relatively low in the low rotation speed range and the high rotation speed range, the amount of smoke emission when the combustion temperature is constant is relatively small in the middle rotation speed range, as shown by the chain line in FIG. There is a tendency to increase in the high speed range and the high speed range.

[0003]

[Devised SUMMARY Meanwhile, as the exhaust gas characteristics of the diesel engine, NO _X and smoke emission levels of are inversely related, it is in a difficult situation to reduce combined both. It is related combustion temperature as a factor, but the combustion temperature is as high as smoke emission amount decreases, NO _X emissions increase, although contrary to the combustion temperature is NO _X emissions decrease low, smoke Emissions increase. Under such circumstances, in recent years, exhaust gas regulations for diesel engines becomes severe, in particular is an important issue to reduce the NO _X emissions.

[0004] In view of the above problems, the present invention considers a frequently used engine in the middle rotation range (especially 60 to 80% of the rated rotation speed).
In the rotation range), it is an object to provide a swirl control device for a diesel engine capable of reducing NO _X emissions while balancing the smoke emissions.

[0005]

According to the present invention, there is provided a swirl control apparatus for a diesel engine for detecting the engine speed, and a variable swirl for adjusting a swirl generated in a combustion chamber. a mechanism, based on the detected value of the rotational speed sensor, Aidori
Low swirl when the engine is in the engine speed range and the medium speed range,
A controller is provided for controlling the variable swirl mechanism so that the swirl is high in the low rotation and high rotation regions than in the middle rotation region.

[0006]

[Operation] According to the swirl control device for a diesel engine according to the present invention, the engine speed is reduced to the idling speed.
If in the middle speed region and when it is in range becomes low swirl, because the combustion temperature is relatively low, NO _X emissions decrease. Further, the swirl is higher in the low rotation speed and high rotation speed regions than in the middle rotation speed region, and the combustion temperature is relatively high, so that the amount of smoke emission decreases. In particular, when a low-swirl when in the idling range the smoke emission amount is small in no-load operation state, the NO _X emissions is reduced, thereby improving the overall exhaust gas characteristics.

[0007]

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, in a diesel engine 1 according to the present embodiment, a piston 5 fitted with a piston ring 4 is slidably provided inside a cylinder liner 3 fitted to a cylinder block 2. A combustion chamber 6 is formed at the top of 5.

The cylinder head 7 is attached to the cylinder block 2 via a gasket 8, and the cylinder head 7 is formed with a valve seat 11 to which an intake valve 10 guided by a valve guide 9 abuts. .
Further, an intake manifold 12 is attached to the cylinder head 7, and an intake passage 13 of the intake manifold 12 is provided.
Are connected to both the main intake port 14 and the sub intake port 15 formed in the cylinder head 7.

The auxiliary intake port 15 is connected to an actuator
The actuator 16 is opened and closed by a valve element 17 driven by the actuator 16. The actuator 16 is connected to a negative pressure pump 19 via a negative pressure pipe 18. The negative pressure pipe 18 is provided with an electromagnetic valve 20. The electromagnetic valve 20 is controlled by a controller 22 to which a detection signal of a rotation speed sensor 21 for detecting an engine rotation speed is input. A mechanism 23 is configured.

In the swirl control device according to the present embodiment,
As shown in FIG. 2, when the engine speed is in the idling speed range and when the engine speed is in the range of 60 to 80% of the rated speed.
The control map is set so that the swirl is low when the engine is in the rotation range and high swirl otherwise.
The variable swirl mechanism 23 is controlled based on the detection value of the rotation speed sensor 21.

When the engine speed is in the idling speed range and when the engine speed is in the middle speed range which is 60 to 80% of the rated speed, the solenoid valve 20 is opened to open the negative pressure pump. By actuating the actuator 16 by 19, the valve element 17
To open the sub intake port 15
The flow of the intake air passing through the main intake port 14 is disturbed by the flow of the intake air passing through the main intake port 14, and the swirl is weakened.

In the engine rotation range other than the above, the solenoid valve 20 is closed, the negative pressure pump 19 is disconnected from the actuator 16, the sub intake port 15 is closed by the valve body 17, and the main intake port is closed.
Smooth the flow of intake air through 14 and increase swirl. The reason for performing such swirl control is as follows. In other words, the medium speed, which is the rotation range of 60 to 80% of the rated speed
In the shift range , the volumetric efficiency with respect to the engine speed is relatively high, and the smoke emission when the combustion temperature is kept constant is relatively small.Therefore, by lowering the combustion temperature as a low swirl, the smoke emission Even if it increases slightly, N
It is more effective to reduce the _OX emission to improve the overall exhaust gas characteristics.

On the other hand, in other engine rotation ranges, the volumetric efficiency with respect to the engine speed is relatively low, and the amount of smoke emission when the combustion temperature is constant is originally relatively large. by increasing the, even NO _X emissions increased slightly, it is better to reduce the smoke emission amount is effective in improving the overall exhaust gas characteristics.

In the idling rotation range, since no-load operation is performed, the amount of smoke discharge is small at both low swirl and high swirl. Accordingly, since the better to low swirl NO _X emissions is reduced, it is effective in improving the overall exhaust gas characteristics. By performing such swirl control, as shown by the solid line in FIG. 4, although the smoke emission amount increases slightly in the medium speed region, significantly reduced in the low speed region and high speed region, whereas, NO _X emissions are 60 to 80% of the speed range of high rated rotational speed frequently used
In the middle rotation range , the smoke emission is significantly reduced in exchange for a slight increase within a range not exceeding the regulation value.

[0015]

According to the present invention, a swirl control device for a diesel engine includes a rotational speed sensor for detecting an engine rotational speed, a variable swirl mechanism for adjusting a swirl generated in a combustion chamber, and a detection value of the rotational speed sensor. Based on this, a controller is provided to control the variable swirl mechanism so that the swirl is low when the engine is in the idling rotation range and the middle rotation range, and the swirl is high in the low rotation and the high rotation range than the middle rotation range. The following effects can be obtained.

By controlling the variable swirl mechanism, the swirl is low when the engine speed is in the idling speed range and when the engine speed is in the middle speed range, and the combustion temperature is relatively low. _X emissions can be reduced, but on the other hand, the swirl is higher in the low and high rotation ranges than in the middle rotation range, and the combustion temperature is relatively high,
Smoke emission can be reduced. In particular, in the idling range the smoke emission amount is small in no-load operation state, by controlling the variable swirl mechanism to the low swirl, it is possible to reduce the NO _X emissions, improve the overall exhaust gas characteristics it can.

[0017] Thus, in the rotation range in the frequently used engine, while balancing between the smoke emission amount can be reduced NO _X emissions, improves the overall exhaust gas characteristics of the NO _X and smoke be able to.

[Brief description of the drawings]

FIG. 1 is a schematic view of a swirl control device for a diesel engine according to an embodiment of the present invention.

FIG. 2 is a control map of the controller shown in FIG.

FIG. 3 is a characteristic diagram of volume efficiency with respect to engine speed in a general diesel engine.

FIG. 4 is a characteristic diagram of smoke emission amount with respect to engine speed in the diesel engine shown in FIG. 1 and a conventional diesel engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diesel engine 6 Combustion chamber 21 Speed sensor 22 Controller 23 Variable swirl mechanism

Claims (1)

(57) [Scope of request for utility model registration] 1. A rotational speed sensor for detecting an engine rotational speed, a variable swirl mechanism for adjusting a swirl generated in a combustion chamber, and an idle rotational speed range and a medium rotational speed range based on a detection value of the rotational speed sensor. A swirl control device for a diesel engine, comprising: a controller that controls the variable swirl mechanism so that a low swirl is set in the case and a high swirl is set in a low rotation range and a high rotation range than in a middle rotation range.