JPS6357822A - Suction device for engine with supercharger - Google Patents

Abstract

PURPOSE:To secure a sufficient supercharging effect, by installing a timing valve, whose open timing is later than that of a main suction port, in a main suction passage, and making the delay free free of adjustment, in case of a suction system provided with the main suction passage and a supercharging passage installing a supercharger side by side. CONSTITUTION:A main suction passage provided with a fuel injection valve 10, a surge tank 11 and a throttle valve 12 is connected to a main suction port 7 of a rotary engine, and a supercharging passage 13 provided with a control valve 14, a surge tank 15 and a supercharger 16 is connected to a supercharging port 8. In the supercharging passage 13 and the main suction passage 9 at the downstream side of the supercharger 16, there is provided with each of timing valves 21 and 22 at both supercharging and main suction sides, rotating synchronously with an eccentric shaft 5 of the engine. And, open timing of the timing valve 22 at the main suction side should be set to be later than that of the main suction port 7, while delay of the open timing is made adjustable by a timing control device 23 to be controlled at a control circuit according to an engine driving state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine that supplies supercharging air from a supercharging passage provided with a supercharger.

(Prior art) In conventional engines, in order to increase filling efficiency and improve output performance, a supercharging passage equipped with a supercharger is provided separately from the main intake passage, and the supercharger pressurizes the engine. Some models are equipped with a supercharging port that supplies air or mixture. In this type of engine, the air supercharged by the supercharger is likely to blow back into the main intake port, and unless this blowback is prevented, a sufficient supercharging effect cannot be obtained.

Therefore, there has been proposed a system in which a timing valve is provided on the downstream side of the supercharger in the supercharging passage, and supercharging is performed from a supercharging port at the end of the intake stroke. For example, special public service in 1987
The device shown in Publication No. 49738 is designed to delay the supercharging timing by installing a timing valve on the supercharging passage side as described above, and also to adjust the supercharging timing according to the engine speed using this timing valve. It has become.

However, with a structure that only adjusts the supercharging timing in this way, the timing is limited to the period from when the timing valve opens to when the main intake port fully closes, that is, the area where the timing valve and main intake port overlap. Blowing back still occurs, and in order to prevent blowback, if the overlapping portion is set smaller, that is, the opening timing of the timing valve is further delayed, the supercharging time will be shortened, and in any case, However, it was difficult to obtain a sufficient supercharging effect.

(Object of the Invention) The present invention is intended to solve the above-mentioned problems, and is an air intake system for a supercharged engine that can maintain sufficient supercharging time and prevent air from blowing back into the main intake port. The purpose is to provide

(Structure of the Invention) The present invention has a main intake passage and a supercharging passage equipped with a supercharger, and in addition to supplying fresh air from the main intake passage, supercharging air is supplied from the supercharging passage at least in the compression stroke. In an engine configured to supply The system is equipped with a control means for adjusting the delay in accordance with the operating state of the engine.

According to this configuration, by opening the timing valve later than the opening timing of the main intake port, the pressure near the main intake port once becomes negative pressure, and then the pressure in the vicinity of the main intake port increases again due to the inertial effect. Since the intake pressure increases in the latter half of the stroke, blowback to the main intake port can be prevented.

Moreover, in order to prevent blowback on the main intake side,
There is no need to unnecessarily delay the supercharging timing as in the past, and the supercharging time can be maintained sufficiently.

Further, the delay in the opening timing of the timing valve is adjusted depending on the operating condition such as the engine speed, for example,
Intake pressure always increases in the latter half of the intake stroke near the main intake port.

(Example) Embodiments of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, 1 is a casing of a rotary piston engine, and this casing 1 is formed by arranging side housings 3 on both sides of a rotor housing 2 having a trochoidal inner peripheral surface 2a. A triangular rotor 4 is provided within the casing 1 and is rotated planetarily by an eccentric shaft 5 while slidingly contacting the trochoidal inner circumferential surface 2a. The flank surface of the rotor 4 and the inner surface of the casing 1 form a variable volume working chamber 6. In the figure, 6a is an intake working chamber, 6b is a compression working chamber,
6C is an exhaust working chamber.

The rotor housing 2 is provided with a spark plug (not shown) for the compression working chamber 6b, and an exhaust port 2b for the exhaust working chamber 6C.

The side housing 3 is provided with a main intake port 7 for the intake operation i[6a, which is opened and closed by the rotor 4 during the intake stroke. A main intake passage 9 equipped with a fuel injection valve 10, a surge tank 11, and a throttle valve 12 communicates with the main intake port 7, and the air-fuel mixture generated by the fuel injected by the fuel injection valve 10 is communicated with the main intake port 7. The air is supplied into the working chamber 6 from the intake port 7. These constitute a rotary piston engine that continuously repeats intake, compression, explosion, expansion, and exhaust strokes in accordance with the rotation of the rotor 4.

On the leading side of the main intake port 7 with respect to the rotational direction of the rotor 4, a supercharging port 8 is provided which opens into the inner surface of the side housing 3 similarly to the main intake port 7. This supercharging port 8 communicates with a supercharging passage 13 that includes a control valve 14, a surge tank 15, and a supercharger 16. The supercharging v116 is equipped with an air pump driven by engine rotation, and feeds pressurized air into the working chamber 6 from the supercharging port 8 to increase charging efficiency. The control valve 14 has its opening degree changed depending on, for example, the load of the engine, and adjusts the amount of supercharging air. The suction side and the discharge side of the supercharging passage 13 are communicated by a bypass passage 17 via a relief valve 18 to prevent excessive supercharging. Further, an air cleaner 19 and an air flow meter 20 are provided upstream of the main intake passage 9 and the supercharging passage 13, and the fuel injected from the fuel injection valve 10 is adjusted based on a signal from the air flow meter 20.

Furthermore, the supercharging passage 13 is provided with a supercharging side timing valve 21 that rotates in synchronization with the eccentric shaft 5 together with a timing valve 22 (described later) provided in the main intake passage 9.

Fig. 3 shows the relationship between the rotation angle of the eccentric shaft 5 and the area of each port. The solid line C is the area of the supercharging side timing valve 21. As can be seen from this figure, the supercharging port 8 starts opening almost simultaneously with the main intake port 7, and is configured to fully close after a predetermined period of time after the main intake port 7 is fully closed. Furthermore, the supercharging side timing valve 21 provided in the supercharging passage 13 starts to open slightly before the main intake port 7 is fully closed, starts supercharging here, and becomes fully open almost at the same time as the supercharging port 8, Stop supercharging. That is, supercharging air can be supplied during the compression stroke. In this way, by delaying the start timing of supercharging by the supercharging side timing valve 21, blowback of supercharging air to the main intake port 7 is prevented to some extent.

Furthermore, in order to reduce blowback in the area where the area of the main intake port 7 and the area of the supercharging side timing valve 21 overlap (the shaded area in FIG. 3), the main intake passage 9 is provided with the supercharging side timing valve 21. The main intake side timing valve 22 rotates in synchronization with the engine.
has been established.

The area of the main intake side timing valve 22 is shown by a solid line in FIG. 3, and its opening timing is set later than the opening timing of the main intake port 7. Furthermore, this timing valve 22 is provided with an advance angle device 23, and the advance angle device 23 is configured to adjust the degree of advance angle by the output of a control circuit 24 that operates in response to the input of the engine rotation speed. It has become. By delaying the opening timing of the main intake passage 9 in this manner, the following effects are obtained.

In FIG. 4, break 1jlE is the pressure waveform near the port 7 in the main intake passage 9 when the main intake side timing pulp 22 is not used, that is, when the opening timing of the main intake passage 9 is not delayed. As can be seen from this graph, the pressure near port 7 begins to drop as soon as port 7 opens, and this negative pressure wave is reflected by surge tank 11 and becomes a positive pressure wave, which returns to intake port 7, causing the second half of the intake stroke. Pressure is mounting. However, in this case, the pressure drop when the port 7 opens is relatively small, and therefore the pressure rise in the latter half of the intake stroke is also small. It is highly conceivable that the air will blow back into the main intake port 7 in the overlapping area of the timing valve 21 . Therefore, in order to avoid blowback under such pressure conditions, the supercharging timing must be delayed, that is, the supercharging time must be shortened.

On the other hand, when the opening timing is delayed by the main intake side timing valve 22, a sudden pressure drop occurs before the timing valve 22 is opened, as shown by the solid line F in FIG. During the delayed week, the pressure rises more rapidly than in the above structure due to inertial effects. As a result, the intake pressure increases in the overlapping portion, and intake air flows from the main intake passage 9 into the casing 1 at a considerable flow velocity, so that blowback into the main intake passage 9 can be prevented. By increasing the intake pressure on the main intake side in this way, blowback can be prevented without extremely delaying the opening timing of the supercharging side timing valve 21, and sufficient supercharging time can be secured. can.

When the engine speed increases, the time for one cycle of the rotary engine becomes shorter, so in order to increase the intake pressure in the latter half of the intake stroke, as in the case of low engine speeds mentioned above, the timing valve 22 must be adjusted at one timing. must be done quickly. In this configuration, as the engine speed increases, the timing valve 22 is advanced by the advance device 23 controlled by the tllIO circuit 24, and the opening timing of the timing valve 22 is advanced.

Note that the structure of the engine to which the present invention is applied is not limited to the above-mentioned one; for example, as shown in FIG. A structure using a single port 78 instead of the supercharging port 80 is also possible. Further, the engine is not limited to a rotary engine, but can also be applied to a general reciprocating engine.

(Effects of the Invention) As described above, the present invention increases the intake pressure in the latter half of the intake stroke due to the inertia effect, which occurs when the opening timing of the timing valve provided in the main intake passage is delayed from the opening timing of the main intake port. , it is possible to prevent supercharging air from blowing back into the main intake port and improve charging efficiency. In this way, blowback is prevented by increasing the intake pressure, so there is no need to reduce the overlap area or shorten the supercharging time unnecessarily as in the past, and the blowback can be achieved while maintaining sufficient supercharging time. This can improve the filling effect.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an engine to which the intake system of the present invention is applied, Fig. 2 is a block diagram of an engine with another structure to which the same intake system is applied, and Fig. 3 shows the rotation angle of the eccentric shaft of the same engine and each FIG. 4 is a graph showing the relationship between the area of the port and the timing valve, and FIG. 4 is a graph showing the relationship between the rotation angle of the eccentric shaft and the pressure near the port in the main intake passage. 7... Main intake port, 9... Main intake passage, 13...
- Supercharging passage, 16...Supercharger, 22... Main intake side timing valve, 23... Advance angle device, 24... Control circuit.

Claims (1)

[Claims] 1. It has a main intake passage and a supercharging passage equipped with a supercharger,
In an engine configured to supply supercharging air from the supercharging passage at least during the compression stroke in addition to supplying fresh air from the main intake passage, a timing valve that opens and closes in synchronization with the engine is provided in the main intake passage. A supercharged engine characterized in that the opening timing of a valve is set to be later than the opening timing of a main intake port, and a control means is provided for adjusting the delay in opening timing according to the operating condition of the engine. Intake device.