JPS5810567B2 - Diesel engine combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device for a diesel engine.

The object of the present invention is to control the swirl ratio generated in the cylinder according to the rotational speed and load of the engine, to optimize the mixture of air and fuel in the cylinder according to the rotational speed and load condition, and to improve engine performance. The aim is to improve fuel efficiency, reduce fuel consumption, and reduce exhaust gas.

The fuel in a diesel engine changes greatly due to the mixing of air and fuel, and in direct injection engines in particular, a swirl is generated within the cylinder to achieve this mixing.

Swirl is created by making the intake port spiral and by adding a shroud to the intake valve.

The strength or weakness of the swirl (swirl speed) is influenced by the rotational speed of the engine.

That is, at low rotations, the swirl is weak, and as the rotation speed increases, the swirl becomes stronger.

However, since the swirl ratio is the ratio of swirl speed/engine rotation speed, the swirl ratio is approximately constant as shown by line 2 in FIG. 2, regardless of whether the engine rotation speed is large or small.

Therefore, at low rotation speeds, the actual swirl ratio is smaller than the ideal swirl ratio, resulting in insufficient air-to-fuel ratio and a large amount of black smoke. The swirl ratio was larger than the ideal swirl ratio, and this also had the problem of increasing black smoke due to overlap of spray fires.

This also depends on the magnitude of the load on the engine, which also affects engine performance and fuel efficiency.

To obtain the optimum combustion of the engine, the rotational speed of the engine,
Regardless of whether the load is large or small, the mixing of air and fuel should be good and balanced.

To achieve this, it is necessary to control the swirl ratio depending on the rotational speed and load condition.

That is, the optimum swirl ratio is to make the swirl ratio small when the load is small, large when the load is medium, and small when the load is high, as shown by the black line in FIG. 1.

As for the engine rotational speed, the ideal swirl ratio is to increase the swirl ratio at low rotational speeds and decrease it as the rotational speed increases, as shown by line 2 in FIG.

In terms of the relationship between the engine speed and the load, it is desirable to set the swirl ratio as shown in the equal swirl ratio map shown in FIG.

Therefore, the present invention automatically controls the above-mentioned ideal swirl ratio and improves it to obtain optimal combustion.

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

1 is an intake port, 2 is an intake valve, and 14 is an intake manifold.

The present invention is that an intake regulating fluid 3 that slides along the inner wall surface of the intake port 1 is provided between the intake valve 2 side and the intake manifold 14 side so as to be movable forward and backward.

The intake regulating fluid 3 throttles the intake air flow supplied to the cylinder 13 when it moves forward toward the intake valve 2 side, and reduces the throttle as it moves backward toward the intake manifold 14 side.

An example of a mechanism for advancing and retracting the intake air conditioning fluid 3 can be implemented with the following configuration.

That is, an operating shaft 4 that is moved forward and backward by a swirl actuator 8 that controls air pressure with a control valve and operates an air cylinder faces into the intake port 1, and a connecting shaft 5 that is pivotally connected to the operating shaft 4 and the intake air conditioning fluid 3. and freely connect 6.

A pressing force is applied by the spring 7 so that the intake regulating fluid 3 always slides into pressure contact with the inner wall surface of the intake port 1.

On the other hand, the swirl actuator 8 includes, for example, an electromagnetic engine speed detection device 10 and a load detection device 11 that is linked to a lever or rack of a fuel injection pump.
It is constructed by combining a control device consisting of a microcomputer 12 that commands opening and closing of control valves.

Note that the reference numeral 9 indicates an air tank. Since the present invention has the above-described structure, the operating shaft moves forward and backward depending on the rotational speed and load condition of the engine, and moves the intake conditioning fluid 3 back and forth in sliding contact with the inner wall surface of the intake port 1. By changing the inflow direction of the intake air supplied into the cylinder 13, the swirl ratio is increased.
It controls the small size.

As described above, at the forward end position A where the intake regulating fluid 3 is closest to the intake valve 2 side, the intake air flow supplied into the cylinder 13 is throttled to increase the flow velocity and the swirl ratio increases.

On the other hand, at the retreating end position B where the intake air conditioning fluid 3 is closest to the intake manifold 14 side, the intake air flow has a reduced throttle, so the flow velocity does not increase and the swirl ratio becomes small.

Furthermore, when the intake air conditioning fluid 3 is located at the intermediate position C, it goes without saying that a swirl ratio intermediate between the front and rear end positions can be obtained.

Therefore, in order to obtain the optimum swirl ratio according to changes in load, such as small, medium, and small, when the load is small and does not require a large swirl ratio, the intake air conditioning fluid 3 is located in retreating section B, and the swirl ratio is set to small. When the load is medium, it is located at the forward end to obtain a large swirl ratio, and when the load is large, it is located at the backward end B to obtain a small swirl ratio.

The reason why the swirl ratio is made small when the load is small is that the fuel injection amount is small when the load is small, so the amount of particulate fuel that comes into contact with the peripheral wall of the cylinder 13 and bounces back is mixed with the air due to the swirl. There are also few.

Therefore, if the fuel spreads too much due to a large swirl ratio, the excess air ratio (the ratio of the amount of air actually existing in the area to the amount of air required for combustion) will increase, moving away from the excess air ratio suitable for combustion. Combustion deteriorates and there is a lot of unburned fuel.

On the other hand, when the load is large, the amount of oxygen required increases, and it is desirable to mix a large amount of oxygen, but if you try to obtain this with a large swirl ratio, the possibility of overlapping with neighboring sprays increases, so it is not always optimal. isn't it.

This is because the black smoke concentration increases due to overlapping sprays.

Therefore, at the engine rotational speed, the optimum swirl ratio holds the relationship between the low load season, the medium load extra large load season, and the high load season.

Next, the relationship between engine speed and swirl ratio is shown in Figure 2■
As shown by the line, the swirl ratio is gradually controlled from large to small as the rotation speed increases.

That is, the intake conditioning fluid 3 is operated backward from the most forward end position toward the backward end as the rotational speed increases.

Of course, reciprocating movements of forward and backward movement are performed at arbitrary positions in accordance with changes in rotational speed to control the swirl ratio appropriate to the rotational speed.

In this way, by controlling the swirl ratio to be large or small depending on the rotation speed, the optimum swirl ratio that always matches the rotation speed can be obtained, and the mixing of fuel and air is always balanced regardless of the rotation speed. This results in effective combustion.

Such a device of the present invention is provided with an intake air conditioning fluid that slides in contact with the inner wall surface of the intake port and moves forward and backward depending on the engine speed and load condition, and the operation of this air intake conditioning fluid changes the inflow direction of intake air supplied into the cylinder. Since the flow is rectified so that the swirl ratio is optimal for the engine speed and load conditions, the mixture of fuel and air in the cylinder is always optimal under operating conditions, and is well-balanced. It has the advantage of achieving combustion, reducing exhaust gas such as black smoke, and ensuring low fuel consumption.

In addition, in the structure, the intake air conditioning fluid is pressed against the inner wall surface of the intake port at the tip of an operating shaft that moves forward and backward in the direction of intake air flow using a swirl actuator based on detection signals from an engine speed detection device and a load detection device. Since they are connected together, they have a simple structure, and have a special effect of automatically and reliably performing the above-mentioned control action by advancing and retracting in one direction.

[Brief explanation of the drawing]

Figure 1 is a curve diagram of the optimum swirl ratio depending on the load, Figure 2 is a graph diagram of the relationship between engine speed and swirl ratio, and Figure 3 is a graph diagram of the relationship between engine speed and swirl ratio.
The figure is an equal swirl ratio map, and FIG. 4 is a sectional view of the main part of the device of the present invention. 1... Intake port, 2... Intake pulp, 3... Intake regulating fluid, 4... Operating axis,
5...Connection shaft, 6...1 connection, 7...
... Spring, 8 ... Swirl actuator, 10 ... Engine rotation speed detection device,
11...Load detection device, 12...Microcomputer, 13...Cylinder, 14...
...Intake manifold.

Claims (1)

[Claims] 1. A swirl actuator that moves forward and backward based on detection signals from an engine rotational speed detection device and a load detection device, an operating shaft that faces into the intake port and moves forward and backward in the flow direction of the intake air by the swirl actuator, and an inner wall surface of the intake port. A streamlined intake regulating fluid that slides in contact with the intake port and provides a variable restriction to the passage of the intake port, and the intake regulating fluid is connected to the operating shaft via a spring that presses against the inner wall surface of the intake port. Combustion control device for diesel engines.