JPS61247823A - Intake apparatus for engine equipped with supercharger - Google Patents

Abstract

PURPOSE:To improve the charging efficiency by setting the valve opening timing of a supercharger side suction valve close to the position where the rate of increase of the cylinder capacity in suction cycle becomes max., in an engine which is equipped with an intake passage equipped with a supercharger and a natural air intake passage and inhales each gas from each suction valve. CONSTITUTION:Each cylinder 8 is equipped with a port 2a into which the pressurized air is supplied from a supercharger 9 and a port 1a for natural-air feed, and suction valves 12 and 7 are installed onto the ports 2a and 1a, respectively. The valve opening timing for the supercharger side suction valve 12 is set at a crank angle of 45 deg. where the rate of increase of the cylinder capacity becomes max. in the suction cycle in which a piston lowers or a little before said crank angle. Therefore, the supercharged air is inhaled at the time when the flow passage of the natural inhaled air is sufficiently high, and the blowing- off into a natural inhaled air passage is prevented, and charging efficiency can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a supercharger equipped with a combustion chamber in which a naturally aspirated passage and a supercharging passage in which a supercharger is interposed are each independently communicated with a combustion chamber. This invention relates to an engine intake system.

[Prior Art] Conventionally, as mentioned above, a supercharged engine having a structure in which a naturally aspirated passage and a supercharging passage are communicated with a combustion chamber is a public 1En-
tsAX 1 space [bR-Q7<)9.7 tatami public introduction)]

By the way, in this type of supercharged engine, each passage is opened and closed by an intake valve, and normally,
The intake valve timing is used to open the supercharging passage when intake through the natural intake passage is almost complete. However, with such intake valve timing settings, the internal pressure of the combustion chamber becomes considerably high due to natural intake, so it is not possible to sufficiently increase the charging efficiency of supercharging air.
In some cases, there is a problem that the intake air is blown back to the supercharging passage side, and there is a problem that the improvement in charging efficiency by the supercharger is not as high as expected.

[Object of the Invention] An object of the present invention is to efficiently transfer supercharging air to the combustion chamber without impairing intake from the natural intake passage by appropriately setting the opening/closing timing of the natural intake passage and the supercharging passage. An object of the present invention is to provide an intake system for a supercharged engine that can supply air to the engine.

[Configuration of the Invention] Therefore, the present invention provides an engine with a supercharger in which a naturally aspirated passage and a supercharging passage with a supercharger interposed therein are each independently communicated with a combustion chamber. It is characterized in that the timing at which the intake boat on the supply side is opened is set at the time when the rate of increase in cylinder volume in the intake stroke is at its maximum, or slightly before that.

[Effects of the Invention] According to the present invention, when the volume increase rate becomes large, the flow velocity on the naturally aspirated side has increased and the suction capacity of the engine is also high, so even if supercharging air is supplied, the naturally aspirated It is possible to provide an intake device that does not impede side intake and can improve supercharging as a whole.

[Example code] Examples of the present invention will be specifically described below.

As shown in FIG. 2, the intake system of the engine E includes a natural intake passage 1 and a supercharging passage 2. As shown in FIG. As shown in the figure, the natural intake passage 1 is arranged in order from the upstream side to the air cleaner 3. The air flow meter 4 is equipped with a throttle valve 5 and a fuel injection valve 6, and when the intake valve 7 of the intake boat la is opened, the fuel and air supplied by the fuel injection valve 6 are supplied to the combustion chamber 8 of the engine E. On the other hand, the supercharging passage 2 is
The natural intake passage 1 is branched from the downstream side of the air flow meter 4, and a supercharger 9 such as a vane-type positive displacement pump is interposed in the middle of the branch, and the air pressurized by the supercharger 9 is transferred to an intercooler 10. The fuel can be supplied to the combustion chamber 8 via the throttle valve 11.

The supercharging passage 2 is opened and closed with respect to the combustion chamber 8 by a supercharging side intake valve 12 of the intake boat 2a. The supercharger 9 is connected via a joint 16 to a pulley 15 that is driven by a timing belt 14 that is rotated around the crankshaft 13 of the engine E, and is driven to rotate approximately in proportion to the rotation of the engine. . Further, the supercharging passage 2 is provided with a return passage 17 that bypasses the supercharger 9 and communicates with the downstream side. When the supercharging pressure rises above the set pressure, the return passage 17 Established! The directional valve 18 is opened to return part of the supercharging air to the suction side to prevent excessive rise in supercharging pressure.

On the other hand, the fuel supplied by the fuel injection valve 6 is controlled by a control unit 1 which receives outputs from the detection section 4a of the air flow meter 4 and the engine speed sensor 20.
9, and as is well known, the amount of fuel injected each time by the fuel injection valve 6 is controlled in accordance with the basic flow rate, the momentary intake air amount, and the engine speed. do.

Next, the intake valve 7 of the natural intake passage l (intake boat la
) and the opening/closing timing of the intake valve 12 (intake boat 2a) of the supercharging passage 2 will be explained with reference to FIG.

As shown in FIG. 1(E), the volume V of the combustion chamber 8 increases from the piston top dead center TDC to the bottom dead center BDC across an inflection point on the way.1. As shown in FIG. 1(D), the volume change rate dV/dθ is approximately 90° from the piston top dead center TDC.
It reaches its maximum at °.

As shown in FIG. 1(A), in the present invention, the opening timing of the intake valve 12 of the supercharging passage 2 is set at a timing approximately 45° before the point where the cylinder internal volume change rate dV/dθ is maximum. so that it starts to open.

Assuming such opening timing, as shown in FIG. 1(C), at the timing when the intake valve 12 of the supercharging passage 2 is opened, the intake flow velocity on the natural intake passage l side is sufficiently high. Since the intake inertia force is also large, natural intake from the natural intake passage 1 is not inhibited even if the supply of supercharging air is started. Also, Figure 1 (A) and (B)
As is clear from the comparison, even if the supercharging passage 2 is opened, supercharging air is not immediately supplied to the combustion chamber 8 immediately after the valve is opened, and supercharging is substantially not carried out between 20 and 30 degrees. Since this is considered to be an ineffective period in which no supercharging is performed, the supply of supercharging air will actually start slightly before the timing at which the change in cylinder internal volume reaches its maximum. Then, the supercharging passage 2 side is closed a little later than when the natural intake ends.

As described above, when the opening/closing timing of the intake valve 7 of the natural intake passage (■), that is, the intake boat 1a on the naturally intake side, and the intake valve 12 of the supercharging passage 2, that is, the intake port 2a on the supercharging side, is set, Substantial supercharging will begin after the timing when natural suction reaches its maximum.
Supercharging air can be supplied at the right time without reducing the intake efficiency of natural intake, and supercharging can be performed at the timing when the rate of change in cylinder volume is at its maximum, so the supercharging efficiency itself can be improved. will improve.

[Brief explanation of the drawing]

FIG. 1 (A), (B), (C), (D), and (E) show the opening area of the intake valve, the pressure inside the intake pipe,
FIG. 2 is a graph showing the intake pipe flow velocity, the rate of change in cylinder volume, and the change in cylinder volume in relation to the crank angle. FIG. 2 is a schematic configuration diagram of a supercharged engine according to an embodiment of the present invention. E... Engine, 1... Natural intake passage, 2... Supercharging passage, 2a... Supercharging side intake boat, 7... Intake valve, End... Combustion chamber, 12... Intake valve. Patent applicant: Mazda Motor Corporation Representative: Patent attorney: Mr. Hajime and two others Figure 1

Claims (1)

[Claims] (1) In a supercharged engine in which a natural intake passage and a supercharging passage with a supercharger are connected to the combustion chamber independently, the timing at which the supercharging side intake port opens is An intake system for a supercharged engine, characterized in that the intake system is set at or slightly before the maximum rate of increase in cylinder volume during the intake stroke.