JPH065030B2 - Intake device for rotary piston engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake device for a rotary piston engine having at least two intake ports.

(Prior Art) Conventionally, for example, as disclosed in Japanese Patent Laid-Open No. 55-25550, in a multi-cylinder engine, two intake ports are opened in each cylinder and the opening / closing timing of each intake port is changed to change the engine. 2. Description of the Related Art An intake system for an engine, which is designed to improve the characteristics of intake charging efficiency in the entire operating range, is known.

Further, in the rotary piston engine, the intake port opens at the end of the exhaust stroke, the pressure in the working chamber is high, and a part of the combustion gas flows back to the intake port.
There is a problem that the combustibility is deteriorated by bringing the exhaust gas into the intake stroke, and improvement of the scavenging property of the combustion gas is required.

(Object of the Invention) In view of the above circumstances, the present invention utilizes the opening / closing timing of a plurality of intake ports opened in one combustion chamber to increase the intake pressure at the opening timing of the intake ports to improve the scavenging property. It is an object of the present invention to provide an intake system for a rotary piston engine as described above.

(Structure of the Invention) An intake device of the present invention has a first intake port and a second intake port that open in one cylinder, and the first intake port and the second intake port communicate with each other through an intake passage. At the same time, the communication distance between the two intake ports is set so that the pressure wave generated at the closing timing of one of the first and second intake ports in the high engine speed region is the same as that of the working chamber next to the other intake port. It is characterized in that the length is set to reach the communication start time.

(Effect of the Invention) According to the present invention, the pressure wave generated by the closing of the intake flow at the closing timing of one of the first and second intake ports with respect to the preceding working chamber is passed through the communication distance to a predetermined value. Propagate the combustion gas in the working chamber to the intake passage to improve the scavenging effect and improve the intake charge efficiency by propagating the pressure to the other intake port that opens with a deviation angle at the opening timing. It can be achieved.

(Example) Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

Embodiment 1 In the rotary piston engine shown in FIGS. 1 and 2, 1 is a rotor housing having a trochoidal inner peripheral surface 1a, and 2a and 2b are side housings arranged on both sides of the rotor housing 1. In the casing formed by the rotor housing 1 and the side housings 2a and 2b, a polygonal rotor 3 supported by an eccentric shaft 5 makes a planetary rotational motion while its top side is in sliding contact with a trochoidal inner peripheral surface. The working chamber 4 is formed.

The first intake port 7 and the second intake port 8 are opened on the inner side surface of the one side housing 2a with respect to the rotor 3, and the inner side surface of the other side housing 2b is
The third intake port 9 is opened. The first intake port 7 is a secondary main port set for medium loads, the second intake port 8 is a secondary auxiliary port set for high loads, and the third intake port 9 is a primary auxiliary port set for light loads. It is a port. An exhaust port 10 is opened in the rotor housing 1.

The intake system that supplies intake air to the intake ports 7, 8 and 9 includes a secondary intake passage 11 connected to the first and second intake ports 7 and 8 and a primary intake passage connected to the third intake port 9. It is formed by branching to 12. Both intake passages 11 and 12 are provided with surge tanks 13 and 14, respectively, on the way, and a primary throttle valve 15 and a secondary throttle valve 16 are arranged on the upstream side of the surge tanks 13 and 14, respectively, and a merging passage 17 is provided in the upstream portion thereof. And is connected to an air cleaner 19 via an air flow meter 18 for measuring the amount of intake air.

A fuel injection nozzle 21 is provided in the secondary intake passage 11.
And the downstream portion is branched and connected by the partition wall 20 to the first branch passage 11a and the second branch passage 11b for the first intake port 7 and the second intake port 8, respectively. The first intake port 7 and the second intake port 8 are communicated with each other at a communication distance L by the first and second branch passages 11a and 11b that bypass the partition wall 20.

In addition, the second branch passage 11 for the second intake port 8
The shutter valve 22 for opening and closing this passage is shown in b.
Is installed. An actuator 23 that operates according to exhaust pressure is connected to the shutter valve 22,
The shutter valve 22 is configured to be opened during high load with a high exhaust pressure according to the operating state of the engine to supply intake air from the second intake port 8 as well.

The openings of the ports 7, 8 and 9 are opened / closed by the rotation of the rotor 3 and are opened / closed at the port timing shown in FIG. The first intake port 7 opens at an early opening timing IO ₁ and closes at an early closing timing IC ₁ as shown by a broken line, and the second intake port 8 opens at a late opening timing IO ₂ as shown by a solid line and is late. Close to the closing timing IC _2. Also,
The third intake port 9 is not shown, but the first intake port 7 is not shown.
It is opened and closed at almost the same port timing as.

The deviation angle Δ between the closing timing IC ₂ of the second intake port 8 and the opening timing IO ₁ of the first intake port 7 with respect to the next working chamber 4.
θ is set to 30 to 70 °.

In the above structure, the pressure wave generated by the closing of the flow of intake air at the closing timing IC ₂ of the second intake port 8 is propagated when the first intake port 7 is opened via the branch intake passages 11a and 11b. It is a thing. The communication distance L is set with respect to the deviation angle Δθ so that the pressure wave propagates through the passage 11 at a sonic speed a and propagates the communication distance L at a time corresponding to the deviation angle Δθ at a predetermined engine speed Ne. To do.

That is, at the engine speed Ne, the time t required to rotate by each deviation Δθ is t = (Δθ × 60) / (360 × Ne), and the time t required for the sonic pressure wave to travel the distance L is Since t = L / a 2, the tuning rotation speed Ne at which the pressure propagation effectively acts is Ne = (Δθ × 60 × a) / (360 × L).

And this tuning speed Ne is the rated speed N of the engine.
It is set to max or less, and preferably set to a high rotation range of 2/3 or more of the rated rotation speed Nmax.

An example of actual port timings of the first intake port 7 and the second intake port 8 together with the deviation angle is as follows.

First intake port Open timing IO ₁ 32 ° after top dead center Close timing IC ₁ 30 ° after bottom dead center Second intake port Open timing IO ₂ 45 ° after top dead center Close timing IC ₂ 80 ° after bottom dead center Δθ = IO ₁ −IC ₂ = 42 ° According to the above embodiment, the shutter valve 22 is maintained in the closed state when the exhaust pressure is low and the load is light, and the first intake port 7 and the third intake port 9 correspond to the required amount. Intake air is supplied. In the above operating range, the blowback of intake air is blocked by the closing operation of the shutter valve 22.

On the other hand, in the high load operation range in which the exhaust pressure rises, the shutter valve 22 is operated by the actuator 23 in the open state, intake air is also supplied from the second intake port 8, and the intake air amount increases. . Further, in the vicinity of the tuning rotational speed Ne, the pressure wave generated when the second intake port 8 is closed propagates through the intake passage 11 to the first intake port 7 in reverse, and the first intake port 7 A scavenging action that increases the pressure when opened to the working chamber 4 to prevent the combustion gas in the working chamber 4 from blowing out to the intake passage 11 and promotes the discharge of the exhaust gas in the working chamber 4 is performed. The output is improved by increasing the intake charging efficiency.

Also, the tuning speed Ne at which the pressure propagation acts at a predetermined time
Is set so as to be in the high speed range of the rated speed Nmax or less, thereby ensuring a sufficient filling amount by a plurality of intake ports having different port timings from the low speed range to the high speed range, and at the same time in the high speed range. In the vicinity of the rotation speed Ne, the filling amount is further increased by the pressure propagation to improve the output performance. In particular, the pressure rise that accompanies the closing of the intake flow at the closing timing of the intake port becomes large in the high-speed and high-load region where the intake amount is large, and the time required for the propagation of the pressure wave and the engine speed are increased in this region. By synchronizing them, the filling efficiency can be effectively improved. Further, when the tuning rotation speed Ne is set low, the communication length L becomes long, the pressure wave itself is small, and the pressure is attenuated during the propagation to reduce the filling efficiency improving effect. Therefore, as described above, the tuning rotation speed Ne is reduced. Is preferably set to a high speed range of 2/3 or more of the rated speed.

In the above-mentioned embodiment, the communication distance L between the first intake port and the second intake port is adjusted by the length of the partition wall, but the partition wall is further extended to the upstream side and pressure is applied to the passage wall. A communication distance may be set by opening a communication port for propagation.

Embodiment 2 As shown in FIGS. 4 and 5, in the rotary piston engine of this embodiment, the first intake port 27 is opened on the inner side surface of one side housing 2a with respect to the rotor 3, and the other side housing 2b is opened. The second intake port 28 is opened on the inner surface. The first intake port 27 is a secondary port with a large opening area set for high load, and the second intake port 28 is a primary port with a small opening area set for light load. An exhaust port 10 is opened in the rotor housing 1.

The intake system that supplies intake air to both intake ports 27, 28 is formed by branching into a secondary intake passage 11 connected to the first intake port 27 and a primary intake passage 12 connected to the second intake port 28. Has been done. Both intake passages 11 and 12 are provided with surge tanks 13 and 14 in the same way as in the previous example, and a primary throttle valve 15 and a secondary throttle valve 16 are provided on the upstream side of the surge tanks 13 and 14, respectively, and upstream portions thereof. Is joined to the merging passage 17 and is connected to an air cleaner 19 via an air flow meter 18 for measuring the amount of intake air.

The secondary intake passage 11 and the primary intake passage 12 are connected to each other by a communication passage 29 on the downstream side of the surge tanks 13 and 14. And the first
The intake port 27 and the second intake port 28 are communicated with each other by the communication passage 29 with a communication distance L.

A shutter valve 30 that opens and closes the passage 29 is installed in the communication passage 29. The shutter valve 30 is configured to be opened / closed in conjunction with, for example, the secondary throttle valve 16, and opened at least at the time of high load / high rotation to open the communication passage 29 and perform pressure transmission.

The first and second intake ports 27, 28 are opened / closed at the port timing shown in FIG. The first intake port 27 opens at an early opening timing IO ₁ and closes at a closing timing IC ₁ as shown by a broken line, and the second intake port 28 opens at a late opening timing IO ₂ as shown by a solid line and closes the same. The second intake port 28 is closed at time IC _2.
The deviation angle Δθ between the closing timing IC ₂ and the opening timing IO ₁ of the first intake port 27 with respect to the next working chamber 4 is set to 70 to 100 °.

In the above structure, the closing timing IC ₂ of the second intake port 28
The pressure wave generated when the flow of intake air is closed is propagated through the communication passage 29 when the first intake port 27 is opened. Then, similarly to the above, the communication distance L is set with respect to the deviation angle Δθ so that the communication distance L is propagated at the time corresponding to the deviation angle Δθ at the predetermined engine speed Ne.

According to the above-described embodiment, in the low rotation speed range in which the shutter valve 30 is closed, the first intake port 27 and the second intake port 28 supply the intake air according to the characteristics of the intake passages 11 and 12, respectively.

On the other hand, in the high rotation speed region near the set rotation speed, the shutter valve 30 is operated in the open state, and the second intake port 28
The pressure wave generated when the
The combustion gas in the working chamber 4 is prevented from blowing out to the intake passage 11 by propagating to the intake port 27 and increasing the pressure when the first intake port 27 is opened. The scavenging action that promotes the outflow of air is improved, the intake charging efficiency is increased by that amount, and the output is improved.

The opening and closing timings of the first intake port and the second intake port may be the same not only at the closing timing but also at the opening timing. At that time, the pressure propagation acts from the second intake port to the first intake port, and also acts similarly from the first intake port to the second intake port, thereby increasing the intake pressure in both intake ports. Is.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a longitudinal section of a rotary piston engine equipped with an intake device according to a first embodiment of the present invention, FIG. 2 is a sectional side view thereof, and FIG. 3 is a view of the first embodiment. FIG. 5 is a characteristic diagram showing opening / closing timings of the first intake port and the second intake port, FIG. 4 is a schematic configuration diagram showing a longitudinal section of a rotary piston engine including an intake device according to a second embodiment of the present invention, and FIG. FIG. 6 is a sectional side view thereof, and FIG. 6 is a characteristic diagram showing opening / closing timings of the first intake port and the second intake port in the second embodiment. 1 ... Rotor housing 2a, 2b ... Side housing 3 ... Rotor, 4 ... Working chamber 7,27 ... First intake port 8, 28 ... Second intake port 11, 12 ... Intake passage 13, 14 ...... Surge tank L …… Communication distance, 29 …… Communication passage 22,30 …… Shutter valve

Claims (1)

[Claims] 1. An intake system for a rotary piston engine having a first intake port and a second intake port opening to one cylinder, wherein the first intake port and the second intake port communicate with each other through an intake passage. At the same time, the communication distance between both intake ports is such that the pressure wave generated when the intake port of one of the first and second intake ports is closed in the high engine speed range is communicated with the working chamber next to the other intake port. An intake device for a rotary piston engine, which is set to a length that reaches the start time.