JPH04121419A - Suction swirl control device of diesel engine - Google Patents

Abstract

PURPOSE:To have a proper control through adjustment of the swirl speed over a wide range so that a proper value is obtained relative to the load, by setting the normal swirl speed to some higher level, and jetting pressurized air being directed opposite the flow of suction air into divergent paths of a suction manifold. CONSTITUTION:A suction port P is formed so that it can hold the swirl speed at a high level. In each divergent path 2 of a suction manifold 1 in connection to the suction port P, an air injection nozzle 18 is provided which has an opening in the direction of jetting air 17 opposite the suction flow 10 leading from the suction manifold 1 to suction port P. These air jetting nozzles 18 are connected with a pressurized air tank 20 through an air pipe 19. This air pipe 19 is fitted with a solenoid valve 21 for opening or shutting it, and a control device 25 is provided, which is fed with an engine revolving speed signal 22 and a load signal 23 and which emits a control signal 24 for controlling opening/ shutting operation of this solenoid valve 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake swirl control device for a diesel engine.

[Prior art] In recent years, swirl control, which is a means of improving combustion for diesel engine exhaust gas countermeasures (NOx countermeasures), has become increasingly important, and various improvements have been made to the shape of the intake port, etc. .

A typical example of the intake port is a helical intake port, as shown in FIGS. 3 to 5.
Inlet portion 8 connected to branch flow path 2 of intake manifold l
an inlet passage 4 extending substantially linearly from the inlet passage 4; a spiral passage 9 extending continuously from the inlet passage 4 and winding around the axis of the valve stem 6 of the intake valve 5 and leading to an opening 8 into the combustion chamber 7;
It is composed of. P indicates an intake port.

As a result, the intake flow lO taken in from the intake manifold l by the opening operation of the intake pulp 5 becomes a swirling flow while passing from the inlet flow path 4 through the spiral flow path 9, and flows into the combustion chamber 7 from the opening 8. Inflow, a strong swirl 11 is formed,
The fuel injected from an injection nozzle (not shown) and the intake air flow 10 are mixed efficiently.

3 to 5, 12 is an exhaust port, 13 is an exhaust valve, 14 is an exhaust manifold connected to the exhaust port 12, 15 is a piston, and 16 is an air cleaner.

On the other hand, recently, a technique has been proposed in which pressurized air is injected into the inlet flow path 4 of the intake port P in the flow direction of the intake air flow 10 to adjust the swirl speed.

Normally, if the swell speed is too high relative to the load (fuel injection amount), a phenomenon occurs in which the fuel sprays in the combustion chamber overlap (overpenetration), which prevents the fuel from becoming atomized and prevents the generation of black smoke. In addition, if the swirl speed is too low relative to the load, the energy of turbulence in the intake air flow will decrease, which will hinder combustion improvement. It is preferable that it can be set to

[Problem to be solved by the invention] However, since the method of controlling the swirl speed by the shape of the intake port P is generally a method of providing intake resistance, there is a problem that fuel efficiency deteriorates due to an increase in pumping loss. Also, there was a problem that the control range of the swirl speed was narrow.

In addition, in the method of injecting pressurized air into the intake port P, the swirl speed is set to be optimal at high rotation speeds under high load, and pressurized air is injected at low rotation speeds. This method maintains a good swirl speed by compensating for the lack of swirl speed, so when the fuel spray speed at partial load is weakened, the swirl speed is maintained high by the engine speed. Since there is no means to reduce the swirl speed, the fuel spray only overlaps, making it impossible to suppress the generation of black smoke, and this case also has the problem of narrowing the control range of the swirl speed.

The control range of the swirl speed in the above conventional method is at most 6 to 1 based on the swirl ratio (a dimensionless value obtained by dividing the rotation speed of the impeller installed in the piston by the engine rotation speed).
．． It was about 4.

The present invention was made by focusing on the above-mentioned conventional problems.
It is an object of the present invention to provide an intake swirl control device for a diesel engine that can select an optimal swirl speed according to fuel at high load and partial load over a wide range without reducing the intake flow rate.

[Means for Solving the Problems] The present invention has an intake port that takes air into each combustion chamber into a shape that maintains a high swirl velocity, and in each branch flow path of the intake manifold connected to the intake port, the intake manifold is connected to the intake manifold. air injection nozzles are disposed for injecting air in a direction opposite to the intake air flow toward the intake port, and each air injection nozzle is connected to a pressurized air tank via an air pipe; An air intake for a diesel engine, characterized in that an air pipe is provided with a solenoid valve that opens and closes the air pipe, and a control device that inputs an engine rotation speed signal and a load signal to control the opening and closing of the solenoid valve. This is related to the swirl control device.

[Function] By setting the swirl speed to a high value, it is possible to improve the swirl speed and improve the mixing with the fuel when the engine speed is low under high load. Furthermore, when the engine speed is high, a control device inputting a speed signal and a load signal opens a solenoid valve, and pressurized air from a pressurized air tank is injected from an air injection nozzle in a direction opposite to the direction of intake air. The swirl rate is then reduced, thereby preventing the swirl rate from becoming too high, resulting in overlapping fuel sprays.

Also, since the fuel injection speed is reduced during partial load,
At this time as well, the solenoid valve is opened by a control device manually controlled by the rotation speed signal and the load signal, and air is injected from the air injection nozzle in the opposite direction to the intake direction to reduce the swirl speed of the fuel. Prevent overlapping sprays.

[Implementation example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of the present invention, and the parts in the figure with the same reference numerals as in FIG. 3 represent the same parts.

The shape of the intake port P shown in FIG. 1 is formed so as to maintain a high swirl speed, and the intake port Air injection nozzles 18 are respectively provided which are opened in a direction to inject air 17 in a direction opposite to the intake air flow lO directed toward P.

Further, each of the air injection nozzles 18 is connected to a pressurized air tank 20 via an air pipe 19.

Further, the air pipe 19 is provided with a solenoid valve 21 for opening and closing the air flowing through the air pipe 19, and further includes an engine rotation speed signal 2.
2 and a load signal 23, and outputs a control signal 24 for controlling the opening/closing operation of the electromagnetic valve 21.

In the above embodiment, as shown in FIG. 2, the shape of the intake port P is selected so that the swirl speed according to the present invention is higher overall than the conventional swirl speed. pumping losses are reduced.

At high loads> As mentioned above, by setting the normal swirl speed to a high value, the engine speed and the swirl speed at low speeds will increase, improving the mixing of air with fuel and improving combustibility. is improved.

When the engine speed is medium to high, the solenoid valve 21 is opened by a control signal 24 from a control device 25 which is manually operated by the engine speed signal 22 and load signal 23.

As a result, the pressurized air 17 in the pressurized air tank 20
The air is injected from the air injection nostle 18 through the air pipe 19 in a direction opposite to the intake air flow lO flowing in the branch flow path 2 of the intake manifold 1.

Therefore, as shown in FIG. 2, the swirl speed on the high-speed side is suppressed, thereby preventing fuel sprays from overlapping.

At partial load> At partial load, such as when driving downhill, the fuel injection speed is weakened, so if the swirl speed increases due to the engine rotation at this time, fuel sprays overlap.

Therefore, also in this case, the rotation speed signal 22 and the load signal 23
By opening the electromagnetic valve 21 by the control device 25 to which the control device 25 is input, pressurized air is injected from the air injection nozzle 18 to reduce the swirl speed and prevent fuel sprays from overlapping.

According to the above-mentioned intake swirl control device of the present invention, conventional six to
The swirl ratio, which was about 1.4, can be increased to 6 to 0, making it possible to control future high-pressure fuel injection (nozzle pressure ~3000 kg/cj).

It should be noted that the intake swirl control device for a diesel engine according to the present invention is not limited to the above-described embodiments, but may also include an air injection nozzle provided in the intake port, injection timing of pressurized air, It goes without saying that the injection amount can be arbitrarily selected and that various other changes can be made without departing from the gist of the present invention.

[Effects of the Invention] As explained above, the intake swirl control device for a diesel engine of the present invention has a normal swirl speed set to a high value, and a branch flow path of the intake manifold.
Since the swirl speed can be adjusted by injecting pressurized air in the opposite direction to the intake flow, the swirl speed can be adjusted over a wide range to maintain an appropriate value for the load at high loads and partial loads. can be adjusted and controlled properly,
Furthermore, excellent effects such as reducing pumping loss at the intake port can be achieved.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a diagram comparing the relationship between engine rotation speed and swirl speed in the case of an embodiment of the present invention and a conventional method; FIG. 4 is a plan view showing an example of a conventional device, FIG. 4 is a perspective view showing an example of a conventional intake port, and FIG. 5 is a cutaway side view of FIG. 4. P is an intake port, ■ is an intake manifold, 2 is a branch flow path, 7 is a combustion chamber, 10 is an intake flow, 17 is air, 18 is an air injection nozzle, 19 is an air pipe, 20 is a pressurized air tank, 2
1 is a solenoid valve, 22 is a rotation speed signal, 23 is a load signal, 25
indicates a control device. Patent applicant Hino Motors Co., Ltd.

Claims (1)

[Claims] 1) The intake port that takes air into each combustion chamber is shaped to maintain a high swirl velocity, and in each branch flow path of the intake manifold connected to the intake port, there is a air injection nozzles for injecting air in opposite directions, each air injection nozzle is connected to a pressurized air tank via an air pipe, and an electromagnetic device is connected to the air pipe for opening and closing the air pipe. An intake swirl control device for a diesel engine, comprising a valve and a control device that inputs an engine rotation speed signal and a load signal to control opening and closing of the electromagnetic valve.