JPS6357821A - Suction device for engine with supercharger - Google Patents

Abstract

PURPOSE:To secure a sufficient supercharging effect, by installing a timing valve, separating from a timing valve in a supercharging passage installing a supercharger side by side, in a main suction passage, as well as installing a device which makes each open timing of both these timing valves into timing advance with a rise in engine speed. CONSTITUTION:A main suction passage 9 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 a supercharger 16, there are provided with respective timing valves 21 and 22 at both supercharging and main suction sides, rotating synchronously with an eccentric shaft 5 of the engine. These valves 21 and 22 are connected to a timing control device 23 to be controlled at a control circuit 24, and the open timing is made so as to be subject to timing advance with a rise in engine speed. And, open timing of the timing valve 22 at the main suction side should be set so as to be deferred later than that of the main suction port 7.

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, in order to adjust the supercharging timing in this way, in the structure of P, the period from the same timing of the timing valve to the main intake port being fully closed, that is, the area where the timing valve and main intake port areas overlap. In order to prevent blowback, blowback still occurs, and if the overlapping portion is set small to prevent blowback, that is, the synchronization of the timing valves is further delayed, the supercharging time will be shortened.Especially At high rotation speeds where one cycle time is short, the supercharging time becomes even shorter, making it difficult to obtain a sufficient supercharging effect.

(Objective of the Invention) The present invention is intended to solve the above-mentioned problems, and is capable of preventing blowback to the main intake port while maintaining sufficient supercharging time over a wide range of engine speeds. It is an object of the present invention to provide an intake system for a supercharged engine that can obtain these effects with a simple configuration.

(Structure of the Invention) The present invention has a main intake passage and a supercharging passage equipped with a supercharger, and provides a supercharging side timing that opens and closes in synchronization with the engine in the supercharging passage downstream of the supercharger. In an engine that is equipped with a valve and 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, the main intake side that opens and closes in synchronization with the engine in the main intake passage. A timing valve is provided, and the timing of the main intake side timing valve is set to be later than the same timing of the main intake port, and the timing of the main intake side timing valve and the above-mentioned supercharging side timing valve is set to be later than the same timing of the main intake port. A means is provided for advancing the angle in synchronization with the rise.

According to this configuration, on the supercharging side, as the engine speed increases, the synchronization of the timing valves becomes earlier, so that sufficient supercharging time can be secured even at high engine speeds.

On the main intake side, on the other hand, since the timing valve opens later than the same time at the main intake port, the pressure near the main intake port once becomes negative, then rises again due to the inertial effect, and during the intake stroke. In the second half, the inspiratory pressure increases,
Air blowback to the main intake port can be prevented. In addition, the same timing of the main intake side valve advances as the engine speed increases, just like the supercharging side, so even if the engine speed increases and the time for one cycle becomes shorter, the intake valve will always be in the same position. Intake pressure increases in the latter half of the stroke.

(Example) A first example of the present invention will be described with reference to FIGS. 1 to 3. 1st
In the figure, 1 is a casing of a rotary piston engine, and this casing 1 is formed by disposing side housings 3 on both sides of a rotor housing 2 having a trochoidal inner peripheral surface 2a. Inside the casing 1, there is a triangular rotor 4 which makes planetary rotational movement by driving the eccentric shaft 5 while slidingly contacting the trochoidal inner circumferential surface 2a.
has been established. 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 the intake working chamber, 6b is the compression working chamber, and 6C
is the 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 working chamber 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. Made from intake port 7! It is designed to be supplied into the lJ chamber 6. These constitute a rotary piston engine that continuously repeats the intake, compression, explosion, intake, 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 supercharging valve 16 . The supercharger 16 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 70-meter 20 are provided upstream of the main intake passage 9 and supercharging passage 13, and the injected fuel from the fuel injection valve 10 is adjusted based on a signal from the air flow meter 20.

Furthermore, the supercharging passage 13 on the downstream side of the supercharger 16 and the main intake passage 9 are provided with a supercharging side timing valve 21 and a main intake side timing valve 22, respectively, which rotate in synchronization with the eccentric shaft 5. There is. These timing valves 21 and 22 are connected to an advance device 23 that is controlled by a control circuit 24, and advance the timing at the same time as the engine speed increases.

FIG. 2 shows the relationship between the rotation angle of the eccentric shaft 5 and the area of each port. First, let us explain the state at low engine speed. In the figure, the single chain IA1 is the main intake port 7. The double-dot chain aBt is the area of the supercharging port 8, the thick solid line FIC1 is the area of the supercharging side timing valve 21, and the thick solid line D1 is the area of the main intake side timing valve 22.

As you can see in this figure, the supercharging port 8 is the main intake port 7
The main intake port 7 begins to open almost simultaneously with the main intake port 7, and is configured to fully open after a predetermined period of time after the main intake port 7 is fully opened. Furthermore, the supercharging side timing valve 2 provided in the supercharging passage 13
1 starts opening later than the supercharging port 8 and slightly before the main intake port 7 is fully closed, and opens fully later than the supercharging port 8. At this time, supercharging is performed by the timing valve 2 on the supercharging side.
This is carried out between the opening of the supercharging port 1 and the closing of the supercharging port 8, so that supercharging air can be supplied during the compression stroke. By delaying the start of supercharging using the supercharging side timing valve 21 in this manner, blowback of supercharging air to the main intake port 7 is prevented to some extent.

Further, a main intake side timing valve 22 is provided to prevent 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. 2). The same timing and closing timing are set later than the same timing and closing timing of the main intake port 7, respectively. By delaying the synchronization of the main intake passage 9 in this way, the following effects can be obtained.

In FIG. 7, the broken line E indicates when the main intake side timing valve 22 is not used, that is, when the main intake passage 9 is opened 1
This is a pressure waveform near port 7 in main intake passage 9 when 91 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. The pressure is building up. However, in this case, the pressure drop when the port 7 opens is relatively small, and therefore the pressure rise at the end 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 .

On the other hand, when the timing valve 22 on the main intake side is used to delay the timing, 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 timing of the timing valve 21 on the supercharging side, and sufficient supercharging time can be ensured. can.

Next, the effect when the engine speed increases will be explained. FIG. 3 shows the relationship between the engine speed and the timing valves at the same time, where a line G1 represents the timing valve 21 on the supercharging side and a line H1 represents the timing valve 22 on the main intake side. Note that in this figure, the vertical axis represents the angle from the same period to BDC. As the timing changes as the engine speed increases as shown in this figure, the area of the supercharging side timing valve 21 moves to the thin solid line CI' in Figure 2, and the area of the main intake side timing valve 21 moves to the thin solid line CI' in Figure 2.
Area 2 moves to the thin solid line D1'. By advancing the timing of each valve at the same time in this way, the following effects are obtained.

If each valve 21.22 regardless of engine speed
If the same period of is delayed, making it impossible to obtain the same effect as at low rotation speeds described above.

However, by advancing the same timing as described above, sufficient turbocharging time is secured on the supercharging side even at high engine speeds, while the main intake side is able to maintain sufficient supercharging time in the latter half of the intake stroke, just as at low engine speeds. 'Can increase air pressure and prevent blowback. The reason blowback can be prevented at high speeds even if the supercharging timing is advanced as described above is because the intake flow velocity is higher than at low speeds, and the flow velocity is further increased by the slow opening effect. be.

Furthermore, according to this configuration, the two valves 21 and 22
The single advance angle device 23 can perform both controls, and the above two effects on the main intake side and the supercharging side can be obtained with a simple mechanism.

Next, a second embodiment will be explained with reference to FIGS. 4 to 6.

Here, in addition to the advance angle VT position 23, as a means for changing the timing, as shown in FIG. The inside of the supercharging passage 13 is partitioned into left and right sides (openings 21a, 22 of valves 21, 22).
The shutter valve 25 is placed on the side that A faces first at the same time.
has been established. Therefore, the opening and closing of the shutter valve 25 changes the position at which the passage begins to open, and the timing of the timing valves 21 and 22 changes even more.

FIG. 6 is a graph showing the relationship between the engine speed and the timing valves at the same time, in which line G2 shows the timing valve 21 on the supercharging side, and line H2 shows the timing at the timing valve 22 on the main intake side.

At low speeds, the shutter valve 25.25 is closed, and one side of the passage 9.13 is closed.

In this state, as the engine speed increases, the advance device 23 advances the angles of both valves 21 and 22 linearly at the same time, as in the actual R example above, but the shutter closes at a certain speed. By opening the valve 25, the moment becomes more intense.

Figure 5 is a graph showing the rotation angle of the eccentric shaft and the area of each port and timing valve. A2 is the area of the main intake port 7, double-dashed line B2 is the area of the supercharging port 8, thick solid line C2 is the area of the supercharging side timing valve 21 at low rotation, and thick solid line D2 is the main intake side timing at low rotation. This is the area of the valve 22. In this figure, when the shutter valve 25.25 opens as the engine speed increases as described above, the areas of the supercharging side timing valve 21 and the main intake side timing valve 22 change to thin solid lines C2' and D2', respectively. do. In this way, by providing the shutter valve 25, it is possible to further increase the degree of change in the advance angle, and as is clear from FIG. can be done.

Note that the engine structure to which the present invention is applied is not limited to the above-mentioned one; for example, the main intake passage 9 and the supercharging passage 13 are merged in front of the casing 1, and the main intake port 7 and the supercharging port 8 are connected to each other. Alternatively, a structure using a single port is also possible. In addition, the engine is not limited to a rotary engine,
It can also be applied to general reciprocating engines.

(Effects of the Invention) As described above, the present invention is capable of reducing the intake pressure in the latter half of the intake stroke due to the inertia effect, which occurs when the timing of the timing valve installed in the main intake passage is delayed from the timing of the main intake port. It is possible to prevent supercharged air from blowing back into the main intake port and improve charging efficiency. Also,
By advancing the timing valves on the main intake side and the supercharging side at the same time as the engine speed increases, sufficient supercharging time can be secured even when the engine is running at high speeds, while reducing the The intake pressure on the main intake side is increased at the same timing as rotation, preventing blowback.

Moreover, since both valves can be advanced at the same time using a single advance device, the effects on the supercharging side and the main intake side can be obtained with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an engine according to a first embodiment of the present invention, Fig. 2 is a graph showing the relationship between the rotation angle of the eccentric shaft of the engine and the area of each port and timing valve, and Fig. 3 is a graph showing the relationship between the rotation angle of the eccentric shaft of the engine and the area of each port and timing valve.
The figure is a graph showing the relationship between the engine speed and the timing valve at the same time, Figure 4 is a configuration diagram of the engine in the second practical example of the present invention, and Figure 5 is the rotation angle of the eccentric shaft of the same engine. A graph showing the relationship between each port and the area of the timing valve, Figure 6 is a graph showing the relationship between the engine speed and the timing valve at the same time, and Figure 7 is the rotation angle of the eccentric shaft of the engine and the main intake passage. It is a graph showing the relationship between the pressure near the internal port. 7... Main intake port, 9... Main intake passage, 13...
・Supercharging passage, 16...Supercharger, 21...Supercharging side timing valve, 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,
A supercharging side timing valve that opens and closes in synchronization with the engine is installed in the supercharging passage on the downstream side of the supercharger, and in addition to supplying fresh air from the main intake passage, supercharging air is supplied from the supercharging passage at least during the compression stroke. In an engine configured to do this, a main intake side timing valve that opens and closes in synchronization with the engine is provided in the main intake passage, and the timing of this main intake side timing valve is set to be later than the same timing of the main intake port. An intake system for a supercharged engine, comprising means for advancing the main intake side timing valve and the supercharging side timing valve in synchronization with an increase in engine speed.