JPS60209659A - Engine equipped with supercharger - Google Patents

Abstract

PURPOSE:To prevent deterioration of the performance of the supercharger by a method wherein gas such as EGR gas, blow-by gas or the like, which is added to suction gas, is permitted to be introduced into the suction system of the engine without exerting the supercharger with adverse effect, in the engine equipped with the supercharger. CONSTITUTION:The engine 1, equipped with the supercharger, is provided with a main suction gas path 14 and a supercharging path 18 in which the supercharger 19 is arranged. At least under high load of the engine, supercharged air is supplied from the supercharging path 18 in the compression stroke of the engine in addition to natural suction from the main suction gas path 14. The engine is further provided with an introducing path 30 for EGR gas, which is extended from an exhaust path 31, and the introducing path 32 for blow-by gas, which is extended from a crank chamber 33. Both introducing paths 30, 32 are opened in the main suction path 14 at the downstream side of a main throttle valve 17. Accordingly, the EGR gas and the blow-by gas, which are added to the suction gas, are supplied into a combustion chamber 6 through the main suction gas path 14, therefore, the supercharger 19 will never be affected adversely by the gas added to the suction gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a supercharged engine that introduces intake supplementary gas such as EGR gas and blow-by gas into the engine intake system.

(Prior art) Some supercharged engines include
As shown in the publication, in addition to the main intake passage, there is also a supercharging passage in which a supercharger is installed, and at least when the engine is under high load, in addition to natural intake from the main intake passage, at least during the compression stroke. There are some that perform so-called partial supercharging, in which supercharging air is supplied from a supply passage.

By the way, in an engine, EGR residue,
Intake supplement gas such as blow-by gas or evaporative gas is introduced into the engine intake system, but if the engine is equipped with a supercharger, this intake supplement gas may flow back to the turbocharger and cause the supercharger to overflow. This may cause deterioration in the performance of the intake gas, so some kind of countermeasure should be taken when introducing this additional intake gas.

(Object of the invention) The present invention has been made in consideration of the above circumstances, and
An object of the present invention is to provide a supercharged engine in which intake air additional scum can be introduced into an engine intake system without adversely affecting the supercharger.

(Structure of the Invention) The present invention is based on the assumption that a supercharged engine is equipped with a supercharging passage in which a supercharger is disposed in addition to a main intake passage, and performs so-called partial supercharging. An additional intake gas such as gas is introduced into the main intake passage downstream of the throttle valve.

(Embodiment) In the figure, 1 is an engine body, and in the embodiment, the engine body 1 rotates a crankshaft 5 as an engine output shaft via a connecting rod 4 by reciprocating movement of a piston 3 within a cylinder 2. It is said to be a reciprocating type.

In the upper part of the combustion chamber 6 defined by the cylinder 2 and the piston 3, in addition to a main intake boat 7 and an exhaust boat 8,
The supercharging boat 9 is opened, and the main intake boat 7 is connected to the main intake valve 1.
0, the exhaust boat 8 is opened and closed by the exhaust valve 1'l at known timings in synchronization with the rotation of the crankshaft 5, respectively, via a timing cam (not shown). Further, the supercharging boat 9 is opened and closed by a supercharging valve 12, and the supercharging valve 12 is operated in synchronization with the rotation of the crankshaft 5 by a timing cam 13.
The main intake valve IO is opened just before the closing timing and is closed during the compression stroke.

The main intake boat 7 is connected to an air cleaner 15 via a main intake passage 14, and the main intake passage 14 includes air flow meters 1 sequentially from the upstream side (air cleaner 15 side).
6. A main throttle valve 17 is provided. Also,
The supercharging boat 9 is connected to the main intake passage 14 via a supercharging passage 18 downstream of the air flow meter 16 and upstream of the main throttle valve 17.
From the upstream side, for example, a positive displacement supercharger 19 such as a vane type, and a water-cooled or air-cooled intercooler 2 are installed.
0, a sub-throttle valve 21 is provided. This sub-throttle valve 21 is interlocked with the main throttle valve 17 so that it begins to open when the main throttle valve 17 receives a high load exceeding a predetermined opening degree.

A relief passage 22 is provided in the supercharging passage 18 . This relief passage 22 has an upstream end connected to the supercharger 1.
9, and the downstream end thereof is opened to the supercharging passage 18 between the intercooler 20 and the sub-throttle valve 21, and a relief valve 23 is connected to such a relief passage 22. . As a result, when the pressure on the downstream side of the supercharger 19, that is, the supercharging pressure, exceeds a predetermined set value, the relief valve 23 opens to relieve supercharging air. Further, the supercharging passage 18 and the main intake passage 14 are communicated with each other by an air bleed passage 24 having a small diameter. This air bleed passage 24 has one end opened to the supercharging passage 18 between the supercharger 19 and the intercooler 20, and the other end opened to the main throttle valve 17.
The main intake passage 14 is opened on the downstream side of the main intake passage 14 . A fuel injection valve 25 is provided at the junction of the air bleed passage 24 with the main intake passage 14, and bleed air from the air bleed passage 24 is supplied to the fuel injected from the fuel injection valve 25. In this way, the atomization of the fuel is promoted.

The supercharger 19 is mechanically driven by the crankshaft 5, and in the embodiment, it includes a pulley 26 provided on the crankshaft 5, a winding medium joint 27 such as a timing belt, and a pulley 26 provided on the crankshaft 5.
8. Power is transmitted via an electromagnetic clutch 29.

In the figure, 30 is an introduction passage for EGR gas extending from the exhaust passage 31, and 32 is an introduction passage for blow-by gas extending from the crank chamber 33. It opens into the main intake passage 14 downstream. An EGR valve 34 is connected to the introduction passage 30 for EGR gas, and a blow-by valve 35 is connected to the introduction passage 32 for blow-by gas. Note that, as in the past, both valves 34 and 35 are opened in a predetermined engine operating state, and the EGR
Gas or blow-by gas is introduced into the main intake road 14.

36 in the figure is a control unit, and the control unit 36 receives an intake air amount signal S from a sensor 37 such as a potentiometer connected to the air flow meter 16.
I + engine speed (rotation speed of crankshaft 5) sensor 3
Engine speed signal S2.8 from S2.8. Throttle sensor 39 detects that the auxiliary throttle valve 21 starts to open
A load signal S3 is input from the control unit 36 and output to the fuel injection valve 25 and the electromagnetic clutch 29. This fuel injection valve 25
The control signal corresponds to the fuel injection amount and is output based on the intake air amount signal S1 and the engine rotation speed signal S2. Further, the control signal for the electromagnetic clutch 29 is such that the electromagnetic clutch 29 is connected (drives the supercharger 19) when the load becomes higher than the set load based on the load signal S. .

Incidentally, intake negative pressure is often used in engines for various control purposes, but this intake negative pressure can be taken out from the negative pressure in the main intake passage 14 on the downstream side of the main throttle valve 17. Bye.

In the above configuration, when the engine load is less than the set load, that is, when the auxiliary throttle valve 21 is closed and the engine load is low, supercharging is not performed because the electromagnetic clutch 29 is disconnected, and the intake air is passed through the main intake passage 14. The combustion chamber 6 is supplied only by natural suction from the combustion chamber 6. On the other hand, when the engine load exceeds the set load, that is, when the sub-throttle valve 21 is opened, the electromagnetic clutch 29 is connected.
Supercharging will take place. Of course, this supercharging is so-called partial supercharging, which is performed from just before the main intake valve 10 closes to midway through the compression process.

Here, EGR gas and blow-by gas as intake additional gas are supplied to the combustion chamber 6 via the main intake passage 14, that is, they are not directly supplied to the supercharging passage 18, so they are not directly supplied to the engine intake system. The supercharger 19 is not adversely affected by the intake additional gas immediately after being introduced.

During supercharging, high-pressure supercharge air is supplied from the supercharging passage to the combustion chamber 6, so that introduction from the combustion chamber 6 through the supercharging passage 18 into the supercharging 119 is also prevented. It turns out. Further, since the sub-throttle valve 21 is closed during low load when supercharging is not performed, backflow from the combustion chamber 6 to the supercharger @19 is also prevented in this case.

Note that when there is no supercharging and the sub-throttle valve 21 is not provided, during the intake stroke, the pressure maintained in the supercharging passage 18 during the compression stroke of the previous stroke causes the main intake passage 14 to
Since the pressure inside the supercharging passage 18 is higher than that inside the combustion chamber 6, immediately after opening the main intake valve 10 and the supercharging valve 12,
Flow from the main intake passage 14 to the supercharging passage 18 is prevented through the main intake passage 14. Also, during the compression stroke, a slight backflow occurs from the combustion chamber 6 to the supercharger 6, but in this case, the intake additional gas is sufficiently diffused within the combustion chamber 6, so the above backflow The proportion of the intake additional gas contained in the gas is extremely small, and liquid impurities that have the greatest adverse effect on the supercharger 19 have a heavy specific gravity, so they are hardly contained in the above-mentioned backflow gas. Even if there is any impact on the feeder 19, it is believed to be extremely small.

Furthermore, as in the embodiment, when a vane type supercharger is used, there is a risk that backflow may occur even during supercharging due to the discharge pulsation of the supercharger.
It is possible to prevent intake additional gas from being carried into the engine 8, thereby preventing an adverse effect on the supercharger.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(2) As the fuel supply device, a carburetor may be used instead of the fuel injection valve 25.

(The supercharger 19 may be kept in a driving state at all times, and supercharging air may be relieved in an operating range where supercharging is not required.

■It can be similarly applied to rotary piston engines; in this case, a timing valve driven by the engine output shaft is provided in the supercharging passage, and the timing to open the supercharging passage, that is, the timing to start supplying supercharging air. It is preferable that the timing valve control the timing valve.

(2) A timing valve as described in (2) above may be provided in the supercharging passage 18 in the embodiment on the downstream side of the sub-throttle valve 21.

(Effects of the Invention) As is clear from the above description, the present invention eliminates the adverse effects of intake additional gas such as EGR gas and blow pie gas on the supercharger, and prevents deterioration of the supercharger while adding intake air to the supercharger. Gas can be introduced into the engine intake system.

In particular, since it is only necessary to set the introduction position of this intake supplementary gas into the engine intake system at a predetermined location, there is no need for a separate special device to prevent the adverse effect of intake supplementary gas on the supercharger. Therefore, it can be implemented easily and at low cost.

[Brief explanation of drawings]

The figure is an overall system diagram showing one embodiment of the present invention. 1: Engine body 14: Main intake passage 17: Main throttle valve 18: Supercharging passage 19: Supercharger 21: Sub-throttle valve 30: Supercharging passage (for EGR gas) 32: Supercharging passage (for blow-by gas)

Claims (1)

[Claims] (1) A main intake passage and a supercharging passage in which a supercharger is disposed, and at least when the engine is under high load, in addition to natural suction from the main intake passage, at least during the compression stroke, intake is carried out from the supercharging passage. In a supercharged engine configured to supply air, an intake additional gas introduction passage for introducing intake additional gas such as EGR gas or blow-by gas into the engine intake system is installed in the main intake passage. le/
A supercharged engine characterized by an opening downstream of the valve.