JPS6340251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a rotary piston engine, and more particularly, the present invention relates to an intake system for a rotary piston engine. This invention relates to a device that uses intake pressure waves to obtain a supercharging effect when the engine is under high load and high rotation speed.

In general, as a two-system side intake port type two-cylinder rotary piston engine, two
A substantially triangular rotor is supported by an eccentric shaft and rotates planetarily within a casing formed by a rotor housing having a nodular trochoidal inner peripheral surface and side housings located on both sides of the rotor housing. A low-load intake passage equipped with a throttle valve and a high-load intake passage equipped with a high-load throttle valve are independently provided in each of the side housings downstream of the low-load throttle valve. The load intake port opens into the working chamber, and the rotor of each cylinder has a phase difference of 180° at the rotation angle of the eccentric shaft, and the above 180° phase difference between the two cylinders. The intake, compression, explosion, expansion, and exhaust strokes are sequentially performed in each cylinder as the rotor rotates while maintaining the
When the engine is under low load, only the low-load throttle valve is opened to supply intake air only from the low-load intake passage, while when the engine is under high load, the high-load throttle valve is also opened and the high-load throttle valve is opened. A so-called dual induction system is known in which intake air is also supplied from the intake passage to increase filling efficiency and improve output. In addition to the type in which the low-load throttle valve is provided in the low-load intake passage, there is also a type in which the low-load throttle valve is provided upstream of the branch between the low-load intake passage and the high-load intake passage.

By the way, it is well known that conventionally, in such a rotary piston engine, a supercharger is installed in the intake passage to supercharge the intake air, thereby increasing the charging efficiency and increasing the output. However, since it requires a supercharger, the structure becomes large-scale and costs increase.

In addition, conventionally, as a technique for obtaining a supercharging effect using intake pressure waves, as disclosed in Japanese Utility Model Publication No. 45-2321, in a single-cylinder rotary piston engine, the intake pipe is divided into two passages of different sizes. The engine is divided into two sections, each with a separate intake port, and when the engine is running at high speeds, two intake passages are used, and when the engine is running at low speeds, the intake passage that is at the later closing position is closed, and the intake air is blocked earlier. , which utilizes the supercharging effect due to intake air blockage at the point of maximum intake pressure, which is a function of intake pipe dimensions and engine speed, to obtain suitable charging efficiency over a wide range of engine speeds. Proposed. But this one is
It was designed for a single-cylinder rotary piston engine, and it was not clear how to utilize the intake pressure waves generated in the intake passage, and its structure and operation were not clear, so it could not be put into practical use right away.
Moreover, since a peripheral port is used as the intake port, the intake port communicates with the exhaust working chamber before the intake working chamber closes, and a supercharging effect can be obtained by blowing back exhaust gas from the exhaust working chamber. was difficult. In particular, in recent years commercially available cars, engine exhaust pressure has increased to reduce noise and purify exhaust gas.
The pressure is about 400 to 600 mmHg (gauge pressure), and in a turbocharged engine it is more than 1000 mmHg, making it impossible to expect improvement in charging efficiency by the peripheral port method.

Therefore, when examining the intake characteristics of the side intake port in a rotary piston engine, the present inventors found that (i) when the intake port is opened, the intake air is compressed by the pressure of the residual exhaust gas in the working chamber, and the air inside the intake passage is compressed. We found that compression waves occur at the intake port (ii) When the intake port is closed, intake air blows back. From this, the above for one cylinder
It has been found that a supercharging effect can be effectively obtained by applying the compression wave (i) to the other cylinder, especially the intake port immediately before fully closing, where the intake air blowback occurs (hereinafter referred to as the exhaust interference effect). It is. As mentioned above, this exhaust interference effect is remarkable because in recent years, catalyst devices for purifying exhaust gas have been installed in engine exhaust systems, resulting in higher exhaust pressures.

Note that, unlike the side intake port type, in the peripheral intake port type in which the intake passage opens into the rotor housing, the above effect does not occur because the intake port always opens into the working chamber.

That is, the present invention provides a two-system side intake port type two-cylinder rotary piston engine as described above, in which the opening period of each intake port, the communication position of at least one intake passage of each cylinder, and the communication position of at least one of each cylinder By appropriately setting the passage length between the intake ports, a supercharging effect can be obtained due to the exhaust interference effect in at least one intake system during high engine speeds of 5,000 to 7,000 rpm, and thus a supercharger etc. can be used. The purpose of this invention is to effectively improve the output by increasing the charging efficiency at high engine load and high rotation speeds through a simple configuration by simply changing the design of the existing intake system.

In order to achieve this objective, the configuration of the present invention is as follows:
A substantially triangular rotor is supported by an eccentric shaft and rotates planetarily within a casing formed by a rotor housing having a nodular trochoidal inner peripheral surface and side housings located on both sides of the rotor housing. A low-load intake passage equipped with a throttle valve and a high-load intake passage equipped with a high-load throttle valve are independently connected to the working chamber by low-load and high-load intake ports provided in each side housing. In a two-cylinder rotary piston engine in which each rotor has a phase difference of 180° with respect to the rotational angle of the eccentric shaft, a. 320°; b. At least one of the low-load and high-load intake passages of each cylinder is connected to the intake passage downstream of the throttle valve by a communication passage; c) The communication passage and its downstream Passage length L between the intake ports of both cylinders formed by the intake passage
is set to 0.57 to 1.37 m, the compression generated in the intake passage when the intake port of one cylinder is opened at high engine speed of 5000 to 7000 rpm in at least one intake system. Supercharging is performed by propagating the waves through the communication passage to the intake port of the other cylinder just before the fully closed state, and therefore the intake port is completely closed due to the exhaust interference effect between the cylinders in at least one intake system. This is designed to effectively increase filling efficiency by suppressing blowback immediately before the filling.

Here, the limitation of 5000 to 7000 rpm as the engine high speed to obtain the above exhaust interference effect is because the maximum output and maximum speed are generally set within this range. This is because it requires a lot of power and is an effective area for improving filling efficiency and power.

In addition, the upper limit of the opening period θ of each intake port in setting item a above, 320°, is to prevent communication between the preceding working chamber and the succeeding working chamber via the side intake port, and is due to the side surface of the rotor. The opening period due to the side seal is approximately
40 degrees larger, and it is necessary to provide an interval of 40 degrees or more in order to avoid this side seal opening period lapping. By suppressing the opening period to less than this, communication between the intake working chamber and the subsequent exhaust working chamber is achieved through the minute gap (usually about 200μ) between the inner sliding surface of the side housing on the outside of the side seal and the rotor side surface. This prevents exhaust gas from entering the intake working chamber during low engine speeds and low loads, such as when idling, and ensures stable combustion. On the other hand, the lower limit of 270° is the minimum period of the geometrical intake stroke from top dead center (TDC) to bottom dead center (BDC). It is necessary to set the period longer than this.

In addition, when setting the downstream position of the throttle valve in the communication passage in setting item b above, the presence of the throttle valve causes a pressure wave (compression wave).
This is to avoid this as it becomes a resistance to the propagation of pressure waves, and to propagate the pressure waves effectively by reducing their attenuation.

Furthermore, the passage length L between the intake ports of both cylinders in setting item c above is set to obtain an exhaust interference effect at high engine speeds of 5000 to 7000 rpm, and L = (θ-180-θ ₀ )×(60/360N)×a...This is the value obtained from the formula (). That is, in the above formula, θ is the intake port opening period and θ=270~
320°, 180° is the phase difference between both cylinders, and θ ₀ is the period from the opening of the intake port until a compression wave is substantially generated at the time of opening, and The invalid period is the sum of the period from just before the intake port is fully closed to when the time compression wave is propagated.
θ ₀ ≈20°, and therefore (θ−180°−θ ₀ ) represents the rotation angle of the eccentric shaft required from generation of a compression wave in one cylinder to propagation to the intake port of the other cylinder. Further, N is the engine rotational speed, N = 5000 to 7000 rpm, and 60/360N represents the time (seconds) required to rotate 1 degree. Also, a is the propagation velocity (sound velocity) of the pressure wave, and at 20°C a=
It is 343m/s. Therefore, from these values, L
= 0.57 to 1.37m.

Incidentally, the opening period of the high-load and low-load intake ports of the present invention is the substantial opening/closing period of the intake ports by the side surface of the rotor, and is not due to the side seal. This is because the minute gap outside the side seal has no substantial effect on the generation and propagation of effective pressure waves in the high rotation range, which is the problem of the present invention.

Furthermore, the above equation () ignores the influence of the flow of intake air on the propagation of pressure waves. This is because the flow velocity is smaller than the speed of sound and causes almost no change in the length of the intake passage.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In Figures 1 and 2, 1A and 1B
are the first and second cylinders in a two-system side intake port type two-cylinder rotary piston engine, one for low load and one for high load.
A and 1B each have a two-section trochoidal inner peripheral surface 2a.
The rotor housing 2 includes a low-load intake port 3 and a high-load intake port 4 located on both sides of the rotor housing 2, in which low-load intake passages 20a, 20b and high-load intake passages 21a, 21b, which will be described later, open respectively. A substantially triangular rotor 7 is supported by a single eccentric shaft 8 and rotates planetarily within a casing 6 formed by side housings 5, 5, and rotors 7, 7 of each cylinder 1A, 1B. is the rotation angle of eccentric shaft 8.
With a phase difference of 180 degrees, the inside of the casing 6 is divided into three working chambers 9, 9, 9 as each rotor 7 rotates, and the above-mentioned
The intake, compression, explosion, expansion, and exhaust strokes are performed sequentially with a phase difference of 180°. Furthermore, 1
0 is an exhaust port provided in the rotor housing 2 in each cylinder 1A, 1B, 11 and 12 are leading side and trailing side spark plugs,
13 is a side seal attached to the side surface of the rotor 7; 14 is an apex seal attached to each top of the rotor 7; and 15 is a corner seal attached to both sides of each top of the rotor 7.

The low-load and high-load intake ports 3 and 4 provided oppositely in the two side housings 5 and 5 are substantially opened and closed by the side surface of the rotor 7, and the opening and closing timings of both are the same, The opening period θ of each intake port 3, 4 is set within a range of 270 to 320 degrees based on the rotation angle of the eccentric shaft 8.

On the other hand, 16 is a main intake passage whose one end opens to the atmosphere via an air cleaner 17 to supply intake air to both cylinders 1A and 1B.
is equipped with an air flow meter 1 that detects the amount of intake air.
8 are arranged. The main intake passage 16 is connected to a main low-load intake passage 20 and a main high-load intake passage 2 by a partition wall 19 downstream of the air flow meter 18.
1, and the main low-load intake passage 20 has a low-load intake passage that opens in response to an increase in engine load and fully opens when the load exceeds a predetermined load to control the amount of intake air when the engine is under low load. A throttle valve 22 is disposed, and the main high-load intake passage 21 is provided with a high-load throttle valve 23 that opens when the engine load exceeds a predetermined load and controls the amount of intake air during high engine loads. It is set up. Further, the main low-load intake passage 20 is branched downstream of the low-load throttle valve 22 into first and second low-load intake passages 20a and 20b having the same shape and dimensions, and then, each cylinder 1
The main high-load intake passage 21 communicates with the working chambers 9, 9 through the low-load intake ports 3, 3 of A and 1B, and the main high-load intake passage 21 is connected to the first and second intake passages of the same shape and size downstream of the high-load throttle valve 23. 2 High load intake passage 21a,
21b, and then communicates with the working chambers 9, 9 via the high-load intake ports 4, 4 of each cylinder 1A, 1B, and therefore, for each cylinder 1A, 1B,
The low-load intake passages 20a, 20b and the high-load intake passages 21a, 21b are configured to open independently into the working chamber 9 downstream of the low-load throttle valve 22.

The passage area As of each of the high-load intake passages 21a, 21b is set to be approximately equal to the passage area Ap of each low-load intake passage 20a, 20b (As=Ap),
Further, the passage length ls of each high-load intake passage 21a, 21b is set shorter than the passage length lp of each low-load intake passage 20a, 20b (ls<lp).
The intake resistance of the high-load intake passages 21a and 21b is reduced to effectively improve filling efficiency. In addition, each of the above-mentioned low-load intake passages 20a, 20
Electromagnetic valve type fuel injection nozzles 24, 24 whose fuel injection amount is controlled according to the output (intake air amount) of the air flow meter 18 are respectively disposed at b.

The branch portion of the main low-load intake passage 20 is located downstream of the low-load throttle valve 22, and includes a first low-load intake passage 20a and a second low-load intake passage 2.
An enlarged chamber 26 having a communication path 25 communicating with 0b
It is composed of. The passage area Acp of the communication passage 25 is such that the passage area Ap of the first and second low-load intake passages 20a and 20b is such that pressure waves (compression waves due to exhaust interference effects) are effectively transmitted with less attenuation. is set to be equal to or greater than (Acp≧Ap). Further, the branching portion of the main high-load intake passage 21 is also constituted by an enlarged chamber 28 having a communication passage 27 that communicates the first and second high-load intake passages 21a and 21b. . The expansion chambers 26 and 28 function as surge tanks during transient operations such as when the engine accelerates or decelerates, and prevent misfires caused by breathing during acceleration or fuel overflow during deceleration, thereby ensuring a good fuel supply. In addition to ensuring responsiveness, the low-load and high-load intake passages 20a,
20b, 21a, 21b become negative pressure, and the expansion waves generated are transferred to the respective intake passages 20a, 20b, 21a,
21b independently inverts and reflects the compression wave in the expansion chambers 26 and 28, and the compression wave is transmitted to each cylinder 1A and 1B.
The supercharging is carried out by propagating the air to each of the intake ports 3 and 4.

Furthermore, the passage length Lp between the low-load intake ports 3 and 3 of the above-mentioned cylinders 1A and 1B is the passage length lcp of the communication passage 25 and the first and second low-load intake passages downstream of the communication passage 25. Each passage length ls of 21a and 21b,
It is the sum of lp and (Lp = lcp + 2lp),
Based on the above formula (), Lp is set to 0.57 to 1.37 (m) based on the high engine speed of 5000 to 7000 rpm.

In FIG. 2, 29 is an exhaust passage connected to the exhaust port 10, and 30 is an enlarged manifold for exhaust purification that assists a catalyst device (not shown) interposed in the middle of the exhaust passage 29. .

Next, to explain the operation of the above embodiment with reference to FIG. 3, when the engine speed is high (5,000 to 7,000 rpm, which requires high output), when one cylinder, for example, the low-load intake port 3 of the second cylinder 1B, is opened, the second The compression wave generated in the load intake passage 20b is generated in both cylinders 1A,
Passage length between low load intake ports 3 and 3 of 1B
By setting Lp to 0.57 to 1.37 m using the above formula () based on the high engine speed of 5000 to 7000 rpm, the second low load intake passage 20b → the communication passage 25 of the enlarged chamber 26 → the first low load intake passage Intake passage 2
0a, it is propagated to the low-load intake port 3 of the first cylinder 1A, which has a phase difference of 180 degrees, just before it is fully closed.
As a result, this compression wave suppresses the blowback of intake air from the low-load intake port 3 immediately before the first cylinder 1A is fully closed, and forces the intake air into the working chamber 9, which results in supercharging. Become. continue,
The compression wave generated when the low-load intake port 3 of the first cylinder 1A is opened is similarly propagated to the low-load intake port 3 of the second cylinder 1B just before it is fully closed, thereby performing supercharging. Thereafter, in the same manner, due to the supercharging effect due to the exhaust interference effect in the low-load intake system between the cylinders 1A and 1B, the charging efficiency is effectively increased when the engine is under high load and high rotation speed, as shown in Fig. 4. Output can be effectively improved. In addition, FIG. 4 shows a case in which the exhaust interference effect is obtained with the present invention at a high engine rotation speed of 6000 rpm as compared to the conventional case (indicated by a broken line) in which there is no exhaust interference effect by blocking the communication passage 25. The output torque characteristics of the engine are shown in the case (shown by the solid line).

At that time, the communication path 25 is connected to the low load throttle valve 22.
It is located downstream, and its passage area Acp is equal to or larger than the passage area Ap of the low-load intake passages 20a and 20b, so the low-load throttle valve 22 and the communication passage 25 themselves generate pressure waves (compression waves) ) is not attenuated, and the above exhaust interference effect can be effectively exhibited.

Further, the supercharging effect due to the exhaust interference effect depends on the opening period of the low-load intake port 3, the position of the communication passage 25 that communicates the first low-load intake passage 20a and the second low-load intake passage 20b, and Both cylinders 1A,
Passage length between low load intake ports 3 and 3 of 1B
Obtained by setting Lp as above,
Since a supercharger or the like is not required, only slight design changes to the existing intake system are required, and the structure is extremely simple, so it can be implemented easily and at low cost.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, in the above embodiment, when the engine rotates at a high speed of 5,000 to 7,000 rpm, the low-load intake system is used to obtain an exhaust interference effect to improve output.
The exhaust interference effect may be obtained in the high-load intake system by setting the passage length Ls between the high-load intake ports 4, 4 of A and 1B to 0.57 to 1.37 m using the above equation (). Also, both intake systems may have an exhaust interference effect; in this case,
The output can be improved by the double exhaust interference effect.

In addition, in a low-load intake system as in the above example,
The exhaust interference effect is set to be obtained at high engine speeds of 5000 to 7000 rpm, while the exhaust interference effect is set to be obtained at 1000 rpm or more lower than the above reference rotation speed (5000 to 7000 rpm) in the high-load intake system. It is also possible to improve the output from the medium speed range to the high speed range of the engine. In this case, in order to obtain the exhaust interference effect at, for example, 3000 to 5000 rpm, the passage length Ls between the high-load intake ports of both cylinders may be set within the range of Ls = 0.82 to 2.29 m from the above equation ().

Furthermore, when the intake port is closed, the intake air is compressed by the inertia of the intake air, and a compression wave is generated at the intake port portion in the intake passage. By applying this closing compression wave to the intake port of the other cylinder just before it is fully closed, a supercharging effect can be obtained (hereinafter referred to as the intake inertia effect). While obtaining the above exhaust interference effect in the system,
The other intake system may be set to obtain the above-mentioned intake inertia effect as shown by the broken line in FIG. 3, and the output can be greatly improved when the engine is under high load and at high speed. In this case, the passage length L to obtain the intake inertia effect is L = (180 - θ ₁ ) x (60/360N) x a (θ ₁ : about 20° in the invalid period, other than the above formula ()) From the equation (similar), L should be set within the range of 1.31 to 1.83 m.

In addition, in the above embodiment, each intake port 3, 4 is configured as a fixed port with a fixed opening period, and the opening period is 270 to 320 degrees, but if the opening period becomes 290 degrees or more, In order to prevent intake air from blowing back, the intake port is configured with a variable port whose opening period is changed by a control valve, and the opening period is 270 to 320 degrees only when the engine is under high load and at high speeds. It is preferable to do so.

Further, in the above embodiment, the opening and closing timings of the low-load and high-load intake ports 3 and 4 are made the same, but they may be shifted as necessary. For example, the opening timing of the intake port on the side that obtains the exhaust interference effect may be shifted. It is preferable to speed up the opening because it can generate a strong compression wave at the time of opening and increase the exhaust interference effect.

In addition, setting the intake/exhaust overlap period to a range of 0 to 20 degrees based on the rotation angle of the eccentric shaft improves charging efficiency and reduces the amount of dilution gas brought in, especially when the engine is under low load. This is preferable in order to prevent misfires.

Further, in the above embodiment, the low load throttle valve 22 is provided in the main low load intake passage 20, but the low load throttle valve 22 is arranged between the main low load intake passage 20 and the main low load intake passage 20. A type provided in the main intake passage 16 upstream of the branching portion with the load intake passage 21 may also be adopted.

As explained above, according to the present invention, in a side intake port type two-cylinder rotary piston engine with two systems for low load and high load, 5000
At high engine speeds of ~7000rpm, the supercharging effect is achieved through the exhaust interference effect between cylinders in at least one intake system, so there is no need for a supercharger, etc., and the design of the existing intake system can be simplified. Even with an extremely simple configuration through modification, it is possible to effectively improve output by increasing charging efficiency when the engine is under high load and high rotation, thereby making it easier to implement measures to improve the output of rotary piston engines and reducing costs. It can greatly contribute to

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram of the overall configuration, FIG. 2 is an overall schematic diagram, FIG. 3 is an explanatory diagram showing the intake stroke of the first and second cylinders, and FIG. 4 is an illustration of the main structure. FIG. 3 is a diagram showing output torque characteristics according to the invention. 1A...1st cylinder, 1B...2nd cylinder, 2...
Rotor housing, 2a...Two-section trochoidal inner peripheral surface, 3...Intake port for low load, 4...Intake port for high load, 5...Side housing, 6...
Casing, 7... Rotor, 8... Eccentric shaft, 9... Working chamber, 20... Main low load intake passage, 20a... First low load intake passage,
20b...Second low load intake passage, 21...Main high load intake passage, 21a...First high load intake passage, 21b...Second high load intake passage, 22...
Throttle valve for low load, 23... Throttle valve for high load, 25
...Communication path.

Claims (1)

[Claims] 1. A substantially triangular rotor is supported by an eccentric shaft in a casing formed by a rotor housing having a two-bar trochoidal inner circumferential surface and side housings located on both sides of the rotor housing. A low-load intake passage and a high-load intake passage that rotate and are equipped with a low-load throttle valve and a high-load intake passage equipped with a high-load throttle valve are independently provided in each side housing. In a two-cylinder rotary piston engine that opens into the working chamber through an intake port, and each rotor has a phase difference of 180° at the rotation angle of the eccentric shaft, a. The rotation angle of the shaft is set within the range of 270 to 320 degrees; b. At least one of the low-load and high-load intake passages of each cylinder is communicated with each other by a communication passage downstream of the throttle valve; c. The length of the passage between the intake ports of both cylinders formed by the communication passage and the intake passage downstream of it is determined by the length of the passage formed in the intake passage when the intake port of one cylinder is opened at high engine speeds of 5000 to 7000 rpm. The intake air of a rotary piston engine is set within a range of 0.57 to 1.37 m so that a compression wave is propagated through the communication passage to the intake port of the other cylinder just before fully closing to perform supercharging. Device.