JPS58167823A - Diesel engine with supercharger - Google Patents

Abstract

PURPOSE:To improve efficiency of an engine, by feeding under pressure to supercharge intake air forcibly fed from a supercharger into a working chamber of the engine from the time about a period to finish closing an intake valve to the time on the half way of a compression stroke. CONSTITUTION:A rotary valve 22 is arranged to the upstream position of a supercharge intake valve 7, despite that the valve 7 is opened at the beginning of an intake stroke and closed on the half way of a compression stroke, the valve 22 is operated so as to open about in a period when an intake valve 5 finishes to close a supercharge intake passage 10 and close on the half way of the compression stroke. Intake air forcibly fed from a supercharger 11 is fed under pressure into a working chamber of an engine from about the period of complete closing of the valve 5 to the half way of the compression stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for increasing the output of the engine in a diesel engine in which the inflow of intake air into the engine working chamber is cut off in the middle of the intake stroke in the (medium) low load region of the engine. Regarding those equipped with a supercharger.

An object of the present invention is to make it possible to obtain a sufficient supercharging effect (that is, an increase in engine torque and output) even if the discharge flow rate of the supercharger is small.

In order to understand the present invention, first, a diesel engine will be described in which intake air is blocked from flowing into the engine working chamber in the middle of the intake stroke in a low (medium) load range of the engine.

FIG. 1 shows an embodiment of a supercharged diesel engine according to the present invention, which includes an intake valve 5, an exhaust valve 6, and a supercharged intake valve 7 driven by a cam.

In the figure, the intake valve 5 closes in the middle of the intake stroke (for example, starts opening at a crankshaft angle of 20 degrees before the top dead center of the piston 2 and closes at 45 degrees before the bottom dead center) to close the intake passage 8. On the other hand, the supercharging intake valve 7 starts opening near the time when the intake valve 5 finishes closing, and closes in the middle of the compression stroke (for example, it starts opening at a crankshaft angle of 65 degrees before the bottom dead center of the piston 2 and after the bottom dead center (closed at 55°).

In addition, the closing valve 9 closes the supercharging intake passage 10 in a low engine load range. (If the closing valve 9 is placed at the position shown by the two-dot chain line, only one valve is required in the case of a multi-cylinder engine).

Now, considering the low load range of the engine with the shutoff valve 9 closed (previously closed), when the intake valve 5 opens and the intake stroke begins, intake air (air) flows from the intake passage 8 to the working chamber 4 (intake air). compression·
A space where combustion, expansion, and exhaust of combustion gas take place.
(refers to the space formed by the cylinder head 1, piston 2, and cylinder 3), and the intake valve 5 closes at mid-speed during the intake stroke, blocking the inflow of intake air (at this time, the closing valve 9 closes). Therefore, even if the supercharging intake valve 7 opens,
(Inspiratory air is not inhaled from here).

Therefore, since the compression ratio can be considered based on the point in time when the power is shut off, the compression ratio is actually low in this case (however, the expansion ratio is higher than this).

Next, when the accelerator pedal (not shown) is further depressed and the closing valve 9 (for example, mechanically interlocked with the accelerator pedal) is opened to increase the load on the engine, the intake air also flows from the supercharging intake passage 10. It is inhaled and the working chamber 4 is completely filled.

In other words, it remains the same as before.

Therefore, at this time, the compression ratio actually becomes a high compression ratio (equal to the expansion ratio).

From the above, it is easy to understand that when the shutoff valve 9 is fully opened, the compression ratio actually becomes a low compression ratio, and when the shutoff valve 9 is fully opened, it becomes a high compression ratio (when the shutoff valve 9 is half open, the compression ratio is also considered to be somewhere in between).

By opening and closing the shutoff valve 9 in this way, the compression ratio is effectively made acceptable, and the advantages obtained from this are as follows: (1) When the shutoff valve 9 is closed, the compression ratio is effectively reduced to a low compression ratio. As a result, engine friction loss is reduced (which leads to improved fuel efficiency), and NOx in exhaust gas is also reduced.

However, since the expansion ratio is the same as the compression ratio when the closing valve 9 is fully open, there is no deterioration in fuel efficiency due to the low compression ratio.

(2) If the closing valve 9 is opened when the engine is started and warmed up, the compression ratio will effectively become a high compression ratio, improving the startability and warm-up characteristics of the engine (in this case, It is preferable to gradually close the closing valve 9 as the engine warms up.)

The above are possible.

It is preferable to fully open the closing valve 9 as soon as possible after it starts to open, and it is also conceivable that the closing valve 9 be of a cylindrical shape that slides up and down.

The present invention provides such a diesel engine with a supercharger so that a sufficient supercharging effect can be obtained even if the discharge flow rate is small.

In the figure, 11 is a supercharger (an exhaust turbo supercharger driven by exhaust gas is shown), 12 is a turbine wheel, 13 is a compressor wheel, and 14 is a supercharging pressure (discharge pressure of the supercharger 11). This is a waste bypass valve that prevents overfilling.

In addition, 15 is an intake circulation valve, which is open when the closing valve 9 is closed (to circulate the intake air), and is closed at the same time as the closing valve 9 is opened (to perform supercharging). This improves the operating characteristics of the machine 11.

As mentioned above, the intake valve 5 closes at the middle speed of the intake stroke, and
The supercharging intake valve 7 starts opening near the time when the intake valve 5 closes and closes in the middle of the compression stroke, and further connects the supercharging intake passage 10 to the supercharger 11.

That is, in the present invention, in the (medium) high load range of the engine when the shutoff valve 9 is opened, the intake air that is pressure-fed from the supercharger 11 is increased so that the intake air that is drawn into the working chamber 4 from the intake passage 8 as before is increased. It is press-fitted into the working chamber 4 from near the time when the valve 5 finishes closing to midway through the compression stroke to perform supercharging.

As a result, the discharge flow rate of the supercharger 11 (supercharging intake passage 10
Even if the intake air flow rate is small, sufficient supercharging effect (
In other words, an increase in engine torque and output can be obtained.

Therefore, it is possible to reduce the effective cross-sectional area of the turbine nozzle, increase the utilization of exhaust energy, and increase the low-speed torque of the engine. It is also possible to increase the rate of increase in torque.

Further, if the supercharger 11 is a mechanical supercharger (for example, a vane pump type supercharger) driven by the crankshaft of the engine, it can be downsized and drive horsepower loss can be reduced.

When applying the present invention to a downstream chamber type diesel engine,
It is preferable that the compression ratio be about 17 when the stop valve 9 is closed, and about 20 when the stop valve 9 is open.

This makes it possible to reduce the friction loss of the engine and NOx in the exhaust gas as described above, and by forcibly opening the shutoff valve 9, it is possible to improve the startability and warm-up characteristics of the engine.

Incidentally, since the period of the supercharging intake valve 7 must be relatively short, a masked valve type is also used to soften the impact and prevent excessive stress from being applied.

Next, in addition to being opened and closed by the accelerator pedal as described above, the closing valve 9 may also be mechanically interlocked with a control rack (not shown) that controls the amount of fuel injection, and thereby opened and closed.

Furthermore, as shown in FIG. 2, it is also conceivable to open and close the closing valve 9 using a switch device 16 and an electromagnet device 17 that detect the fuel injection amount control position of the control rack 18.

That is, in the low (medium) load range of the engine, the internal contacts of the switch device 16 are open as shown in the figure, and therefore the closing valve 9 is closed (fully closed), but in the (medium) high load range of the engine In the area, when the control rack 18 moves (fuel injection amount increases) and reaches the stepped part 19, the push load 2
Since 0 falls here, the contacts inside the switch device 16 are closed and the electromagnetic device 17 is energized.

As a result, the electromagnet built into the electromagnet device 17 pulls in the rod 21 against the spring, so the closing valve 9 opens (
full throttle).

Incidentally, since the intake circulation valve 15 in FIG. 1 needs to be instantaneously closed at the same time as the closing valve 9 opens, it is desirable to open and close it using such an electromagnetic device 17.

In the embodiment shown in FIG. 3, a rotary valve 22 is installed upstream of the supercharging intake valve 7, and even though the supercharging intake valve 7 opens at the beginning of the intake stroke and closes in the middle of the compression stroke, the rotary valve 22 is installed at the upstream position of the supercharging intake valve 7. The valve 22 opens the supercharging intake passage 10 near the time when the intake valve 5 finishes closing, and closes it in the middle of the compression stroke, so that the intake air fed under pressure from the supercharger 11 is transferred to the supercharging intake passage 10 until the intake valve 5 finishes closing. It is designed to be press-fitted into the working chamber of the engine from around the time of compression stroke to the middle of the compression stroke.

That is, in addition to the intake air taken in from the intake passage 8 as described above, the intake air supplied from the supercharger 11 is pressurized into the working chamber of the engine to perform supercharging.

Thereby, even if the discharge flow rate of the supercharger 11 is small, a sufficient supercharging effect can be obtained.

Furthermore, since the opening mechanism of the supercharged intake valve 7 is sufficiently long, no excessive stress is generated.

Reference numeral 9 denotes a closing valve that closes the supercharging intake passage 10 in a low (medium) load range of the engine.

It goes without saying that the intake valve 5 closes in the middle of the intake stroke, and the intake passage 8 bypasses the rotary valve 22 (passes directly above or below it) and connects to the working chamber of the engine.

As described above, the present invention is provided with an intake passage having an intake valve and a supercharging intake passage having a supercharging intake valve, and the supercharging intake passage is connected to a supercharger, and the intake valve is connected in the middle of the intake stroke. In addition to the intake air drawn into the working chamber of the engine from the intake passage, the intake air compressed by the supercharger is fed into the engine from near the time when the intake valve finishes closing until midway through the compression stroke. Since the supercharging intake passage is pressurized into the working chamber of the engine and the supercharging intake passage is closed in the low load range after the engine is warmed up, the discharge flow rate of the supercharger is small. However, a sufficient supercharging effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a supercharged diesel engine according to the present invention, Fig. 2 is a diagram showing a method of opening and closing a closing valve, and Fig. 3 is a diagram of a supercharged diesel engine according to the present invention (schematically shown). This is a drawn plan view). 11 is a cylinder head, 2 is a piston, 3 is a cylinder, 4 is a working chamber, 5 is an intake valve, 6 is an exhaust valve, 7 is a supercharged intake valve, 8 is an intake passage, 9 is a closing valve, 10 is a supercharged intake 11 is a supercharger, 12 is a turbine wheel, 13 is a compressor wheel, 14 is an exhaust bypass valve, 15 is an intake circulation valve, 16 is a switch device, 17 is an electromagnet device, 1
8 is a control rack, 19 is a stepped portion, 20 is a push rod, 21 is a rod, and 22 is a rotary valve. Patent applicant Osamu Kitamura■

Claims (1)

[Claims] (1) An intake passage having an intake valve and a supercharging intake passage having a supercharging intake valve are provided, the supercharging intake passage is connected to a supercharger, and the intake valve is closed in the middle of the intake stroke. , and further increases the amount of intake air sucked into the working chamber of the engine from the intake passage, so that the intake air that is pressure-fed by the supercharger is transferred to the working chamber of the engine from near the time when the intake valve finishes closing to in the middle of the compression stroke. A diesel engine with a supercharger, characterized in that the supercharging intake passage is press-fitted to perform supercharging, and the supercharging intake passage is closed in a low load range after the engine has been warmed up.