JPH0329968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an intake system for a rotary piston engine, and more specifically, in a side intake port type two-cylinder rotary piston engine, the present invention relates to an intake system for a rotary piston engine. It relates to a device that uses this technology to obtain a supercharging effect when the engine rotates at high speeds.

(Prior Art) In general, a side intake port type two-cylinder rotary piston engine has a rotor housing with a two-section trochoidal inner peripheral surface, and a side intake port with an intake passage located on both sides of the rotor housing. A substantially triangular rotor is supported by an eccentric shaft and rotates planetarily within the casing formed by the housing, and the rotor of each cylinder rotates at the rotation angle of the eccentric shaft.
It has a phase difference of 180°, and the above
The intake, compression, explosion, expansion, and exhaust strokes are sequentially performed in each cylinder as the rotor rotates while maintaining a 180° phase difference.

By the way, conventionally, in such a rotary piston engine, a supercharger is provided in the intake passage.
It is well known that supercharging the intake air increases charging efficiency and increases output, but the requirement for a supercharger requires a large-scale structure and increases costs.

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. In order to obtain suitable charging efficiency over a wide range of engine speeds by utilizing the supercharging effect caused by intake air blockage at the point of maximum intake pressure, which is a function of the intake pipe dimensions and engine speed, (Means for solving the problem and its effect) This problem is for a single-cylinder rotary piston engine, and it is unclear how to utilize the intake pressure waves generated in the intake passage, its structure, and its effect, and it is not immediately practical. It was something that could not be served. Moreover, since a periport is used as the intake port, the intake port communicates with the exhaust working chamber before the intake working chamber closes, making it difficult to obtain a supercharging effect due to exhaust gas blowing back from the exhaust working chamber. It was hot. Especially in recent commercial cars,
Engine exhaust pressure increases to reduce noise and purify exhaust gas, and at high speeds and high loads, a normal engine will have a pressure of 400~
The pressure is about 600mmHg (gauge pressure), but in a turbocharged engine it is more than 1000mmHg, so we cannot expect to see any improvement in charging efficiency using the periport method.

Therefore, the present inventors studied the intake characteristics of the side intake port in a rotary piston engine, and found that when the intake port is closed, the intake air is compressed due to the inertia of the intake air, and a compression wave is generated in the intake passage. It was discovered that an expansion wave is generated in the intake passage when the intake starts. From this, it can be seen that a supercharging effect can be obtained by applying the above-mentioned compression wave at closing in one cylinder to the intake port of the other cylinder, especially just before fully closing, where intake air blowback occurs (hereinafter referred to as intake inertia effect). ), and if the above expansion wave in each cylinder is reversed into a compression wave and applied to the intake port of each cylinder just before fully closing, a supercharging effect can be obtained (hereinafter referred to as intake individual pulsation). They discovered that the effects of In particular, the intake inertia effect is more significant in rotary piston engines than in reciprocating engines because the slope of the intake port closing characteristic is steeper and the degree of pressure rise is greater.

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 side intake port type two-cylinder rotary piston engine as described above, in which the opening period of the intake port is controlled by the position of the expansion chamber for communicating the intake passages of each cylinder and for reversing expansion waves into compression waves. By appropriately setting the length of the passage from the enlarged chamber to the intake port of each cylinder and the length of the passage between the intake ports of both cylinders, the above-mentioned intake air Supercharging is performed by the inertia effect and the intake air pulsation effect, and the charging efficiency at high engine load and high revolutions can be improved with an extremely simple configuration by making slight design changes to the existing intake system without using a supercharger etc. The purpose is to increase the output power by increasing the output power.

In order to achieve this objective, the configuration of the present invention is as follows:
A roughly triangular rotor is mounted on an eccentric shaft inside a casing formed by a rotor housing with a trochoidal inner circumferential surface and a side housing equipped with intake ports located on both sides of the rotor housing with intake ports opening into intake passages. In a two-cylinder rotary piston engine that is supported and performs planetary rotation, and each rotor has a phase difference of 180° at the rotation angle of the eccentric shaft, a) the opening period θ of the intake port is defined as the rotation angle of the eccentric shaft. (b) Providing an enlarged chamber downstream of the throttle valve that has a communication passage that communicates the intake passages of each cylinder; c) Formed by the communication passage and the intake passage downstream thereof. Passage length L between the intake ports of both cylinders
Under the conditions that d is set to be 1.31 to 1.83 m, and d is the length of the intake passage from the enlarged chamber to the intake port of each cylinder, l ₁ is set to be 0.35 to 0.63 m. At high engine speeds of 5000 to 7000 rpm, the compression waves generated in the intake passage when the intake port of one cylinder is closed are propagated through the communication passage to the intake port of the other cylinder just before it is fully closed. The expansion wave generated in the intake passage by the start of intake at the intake port of the cylinder is inverted in the expansion chamber, and the secondary pulsating wave of the reflected compression wave is propagated to the intake port of each cylinder just before it is fully closed. Therefore, due to the intake inertia effect between the cylinders and the unique intake pulsation effect of each cylinder itself, the charging efficiency is significantly increased when the engine is under high load and at high rotation speeds. .

Here, at the time of high engine speed mentioned above,
The limit of 5000 to 7000 rpm is because the maximum output and speed are generally set within this range.
This is because it is a high-load, high-speed operating region of the engine, and is an effective region for improving charging efficiency and output.

In addition, the upper limit of the intake port opening period θ 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. The opening period due to the side seals is approximately 40° longer than the opening period, and in order to avoid the side seal opening period from lapping, it is necessary to provide an interval of 40° or more between them.
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, thereby ensuring 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 opening period longer than this.

Incidentally, the opening period of the intake port of the present invention is the substantial opening/closing period of the intake port by the side surface of the rotor, and is not due to the side seal. this is,
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.

In addition, when setting the downstream position of the throttle valve in the expansion chamber with the communication passage in setting item b above, the presence of the throttle valve causes pressure waves (compression waves and expansion waves).
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 the above setting c is set to obtain the intake inertia effect, L=(180-θ ₀ )×30/360N×c... This is the value obtained from equation (1). That is, in the above equation, 180° is the phase difference between both cylinders, and θ ₀ is the period from when the closing compression wave is generated until the intake port is fully closed, and the intake port through which the closing compression wave is propagated. This is the invalid period, which is the sum of the period from just before fully closing to fully closed, and θ ₀ ≒ 20°, so (180 − θ) is the period from the generation of compression wave at closing in one cylinder to the intake air in the other cylinder. Represents the rotation angle of the eccentric shaft required to propagate to the port. Also, N is the engine rotation speed, N = 5000 to 7000 rpm,
30/360N represents the time (seconds) required to rotate 1°. Further, C is the propagation speed of pressure waves, that is, the speed of sound, and at 20° C., C=343 m/s. Therefore, from these values, L=1.31 to 1.83 m.

Furthermore, the passage length l ₁ between the enlarged chamber and the intake port of each cylinder in setting item d above is set to obtain the intake individual pulsation effect, and l ₀ = (θ−θ ₁ )×60/360N×C×1/2Z...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°, and θ ₁ is the period from the opening of the intake port until the expansion wave is generated, and the period from just before the intake port is fully closed to when the secondary pulsation wave of the compression wave, which is the inversion of the expansion wave, is propagated. The invalidity period is the sum of the
θ ₁ ≈100°, and therefore (θ−θ ₁ ) represents the rotation angle of the eccentric shaft required from the generation of the expansion wave to the propagation of the secondary pulsating wave of the compression wave. Also,
Engine rotation speed N = 5000 to 7000 rpm and 60/360N ₁ represents the time (seconds) required to rotate 1°. Also,
The propagation velocity of the pressure wave is C = 343 m/s (at 20°C). Further, since Z is a positive order of the pulsating wave and uses the secondary pulsation, Z=2, and 1/2Z represents the reciprocal of the stroke of the secondary pulsation twice. Therefore, from these values, l ₁ =0.35 to 0.63 m.

Here, in the present invention, the reason why secondary pulsation is used to obtain the intake-specific pulsation effect is that while primary pulsation has the above-mentioned effect, the passage length l ₁ becomes too long, and 2 Since the length is twice as long as that in the case of the next pulsation, it is difficult to mount it on a vehicle and tends to increase the intake resistance. On the other hand, in the case of tertiary pulsation, the path length l ₁ becomes 2/3 shorter than that of second-order pulsation, but on the other hand,
The above effect is reduced by about 15 to 25% with respect to secondary pulsation, and the intake resistance does not change much. For this reason, the purpose is to effectively exhibit the intake-specific pulsation effect while making the passage length _l1 as short as possible.

Note that in equations () and (), the influence of the flow of intake air on the propagation of pressure waves is ignored. 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.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

In Figures 1 and 2, 1A and 1B
are the first and second cylinders in a side intake port type two-cylinder rotary piston engine, and each cylinder 1A, 1B has a rotor housing 2 having a two-section trochoidal inner peripheral surface 2a,
Intake passages 16a and 16b, which will be described later, are located on both sides of the intake passages 16a and 16b.
A substantially triangular rotor 6 is driven by an eccentric shaft 7 inside a casing 5 formed by side housings 4, 4 each having an intake port 3 with an opening.
The cylinders 1A, 1A,
The rotors 6, 6 of 1B have a phase difference of 180 degrees in the rotation angle of the eccentric shaft 7, and as the rotors 6 rotate, the inside of the casing 5 is divided into three working chambers 8, 8, 8, In each cylinder 1A, 1B, the intake, compression, explosion, expansion, and exhaust strokes are sequentially performed with a phase difference of 180°. In addition, 9 is an exhaust port opened in the rotor housing 2 for each cylinder 1A, 1B, 10 and 11 are leading side and trailing side spark plugs, 12 is a side seal attached to the side of the rotor 6, and 13 is a rotor 6 Apex seals 14 are attached to the respective neck portions of the rotor 6, and corner seals 14 are attached to both sides of the respective neck portions of the rotor 6.

The intake port 3 is opened and closed by the side surface of the rotor 6, and the opening period θ of the intake port 3 is set in the range of 270 to 320 degrees based on the rotation angle of the eccentric shaft 7.

On the other hand, 15 is the air cleaner, 16 is both cylinders 1
The main intake passage 16 is a main intake passage for supplying intake air to A and 1B, and an air flow meter 17 for detecting the amount of intake air and a throttle valve 18 for controlling the amount of intake air are disposed downstream of the air flow meter 17. has been done. The main intake passage 16 is branched into first and second intake passages 16a, 16b of equal length, and then communicated with the working chambers 8, 8 of each cylinder 1A, 1B via the intake ports 3, 3, Furthermore, electromagnetic valve type fuel injection nozzles 19, 19 are provided in the first and second intake passages 16a, 16b, respectively, to control the fuel injection amount according to the output of the air flow meter 17.
is installed.

The branch part of the main intake passage 16 is located downstream of the throttle valve 18, and the branch part is located downstream of the throttle valve 18.
It is constituted by an enlarged chamber 21 having a communication passage 20 that communicates the intake passage 16a and the second intake passage 16b. The passage area of the communication passage 20 is set to the first and second intake passages so as to reduce the attenuation of pressure waves (compression waves due to the intake inertia effect) and effectively transmit them.
It is set to be equal to or larger than the minimum passage area of 6a and 16b. Further, the volume of the expansion chamber 21 is set to be 0.5 to 2 times the engine displacement (or the total if two intake ports are provided, one for low load and one for high load).
If it is less than 0.5 times, the reversal effect between expansion waves and compression waves cannot be obtained, while if it is more than 2 times, the pressure waves will be diffused and the unique pulsation effect of the intake air will be significantly reduced. Further, the enlarged chamber 21 functions as a surge tank for intake air during transient operation such as acceleration or deceleration of the engine, and ensures good fuel response.

In addition, the intake ports 3 of the above-mentioned both cylinders 1A and 1B,
3 is the passage length L of the communication passage 20 and the _first and second intake passages 16 downstream of the communication passage 20.
It is the sum of the respective path lengths l ₁ and l ₁ of a and 16b (L=l ₂ +2l ₁ ), and the path length L is 5000 to
Based on the above equation (), based on the engine high speed of 7000 rpm, it is set as L=(180-20)×60/360×(500-700)×343≒1.31-1.83 (m). In this case, the above passage length
l ₁ and l ₂ each take the center length of each passage.

Furthermore, the first and second intake passages 16a, 16
b passage length l ₁ , that is, each intake passage 16a, 1
The passage length l ₁ from the opening end face to the expansion chamber 21 of 6b to the opening to the working chamber 8 (intake port 3) is 5000
Based on the above formula () based on the high engine speed of ~7000 rpm, l ₁ = {(270 ~ 320) - 100} × 60 / 360 × (5000 ~ 7000) × 343 × 1/2 × 2 ≒ 0.35 ~ 0.63 ( m) is set.

In FIG. 2, 22 is an exhaust passage connected to the exhaust port 9, and 23 is an enlarged manifold for exhaust purification that assists a catalyst device (not shown) interposed in the middle of the exhaust passage 22.

Next, the operation of the above embodiment will be explained with reference to FIG. 3. At high engine speeds of 5000 to 7000 rpm,
The compression wave generated in the second intake passage 16b when the intake port 3 of one cylinder, for example, the second cylinder 1B, is closed increases the passage length L between the intake ports 3 and 3 of both cylinders 1A and 1B by 5000 to 7000 rpm. 1.31 to 1.83m according to the above formula () based on the high engine speed of
By setting this to , the air is propagated through the second intake passage 16b → the communication passage 20 of the enlarged chamber 21 → the first intake passage 16a to the intake port 3 of the first cylinder immediately before fully closing, which has a phase difference of 180°. . Similarly, the first cylinder 1A
The compression wave generated when the intake port 3 is closed is propagated to the intake port 3 of the second cylinder 1B just before it is fully closed, and thereafter the intake inertia effect is similarly obtained between the cylinders 1A and 1B.

At the same time, in each cylinder 1A, 1B, the intake port 3 starts to intake air, and the first and second intake passages 1
The expansion waves generated in 6a and 16b increase the passage length _l1 between each intake port 3 and the expansion chamber 21 by 5000~
By setting it to 0.35 to 0.63 m using the above formula () based on the high engine speed of 7000 rpm, the distance between the first and second intake passages 16a, 16b → expansion chamber 21 (inverted and reflected by the compression wave) → the first , second intake passages 16a, 16b→intake port 3 (inverted and reflected by expansion wave)→first and second intake passages 16a, 16
b → Expansion chamber 21 (reflected as a compression wave) → Via the first and second intake passages 16a and 16b, it is transmitted as a secondary pulsating wave of the compression wave to the intake port 3 of each cylinder 1A and 1B just before fully closing. This is propagated, and a unique intake pulsation effect is obtained in each cylinder 1A, 1B itself.

Therefore, due to the intake inertia effect between the cylinders 1A and 1B on the intake port 3 of each cylinder 1A and 1B immediately before fully closing, and the individual intake pulsation effect of each cylinder 1A and 1B themselves, The blowback of the intake air from the intake port 3 is suppressed and the intake air is forced into the working chamber 8, which results in supercharging. Therefore, as shown in Figure 4, 5000 ~
The charging efficiency at high engine speeds of 7000 rpm increases significantly, making it possible to significantly improve output. In addition, Fig. 4 shows the case when the engine is running at high speed.
In contrast to the case where the intake passage is made independent for each cylinder to obtain only the second-order intake unique pulsation effect (indicated by the broken line) based on 6000 rpm, in addition to this, the intake inertia effect is also obtained based on 6000 rpm. This figure shows the output torque characteristics of the engine when the engine is configured to obtain (shown by the solid line).

Further, the expansion chamber 21 having the communication passage 20 is
Since it is located downstream of the throttle valve 18, the pressure waves are not attenuated by the throttle valve 18, and the above-mentioned intake inertia effect and intake unique pulsation effect can be effectively exerted, and the supercharging effect is It is possible to ensure that

Furthermore, the supercharging effect due to the intake inertia effect and the intake individual pulsation effect is achieved by the communication passage 20 that communicates the first intake passage 16a and the second intake passage 16b during the opening period of the intake port 3 of each cylinder 1A, 1B. the position of the enlarged chamber 21, the length L of the passage between the intake ports 3, 3 of both cylinders 1A and 1B, and the enlarged chamber 2
This can be obtained by setting the passage length _l1 between the intake port 1 and the intake port 3 as described above, and since a supercharger etc. is not required, a slight design change to the existing intake system is required, and the structure This is extremely simple and can therefore be implemented easily and at low cost, making it possible to greatly simplify the structure and reduce costs.

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, an example was shown in which the present invention was applied to a fuel injection type rotary piston engine, but it goes without saying that the present invention can also be applied to a carburetor type engine. However, in the case of a fuel injection type, the fuel injection nozzle 19 is connected to the communication passage 20 (the enlarged chamber 2
1) By providing the downstream intake passages 16a, 16b, the passage length of the intake passages 16a, 16b can be reduced.
This is preferable because deterioration in fuel responsiveness due to an increase in l ₁ can be prevented.

Furthermore, in the above embodiment, a case has been described in which one intake passage 16a, 16b is provided for each cylinder 1A, 1B, but the present invention provides independent low-load and high-load intake ports with different intake ports for each cylinder. It can also be applied when providing two intake passages, one for the load and one for the load. In this case, both or one of the two intake systems may be set to obtain the intake inertia effect and the intake unique pulsation effect. However, in the case where the two systems of intake ports have different closing timings, it is preferable to set the closing timing to the later one to obtain the above effect.

Furthermore, the opening timing of each cylinder's intake port is 30 degrees or more based on the rotation angle of the eccentric shaft after top dead center.
It is preferable to set the angle in the range of 60° in order to improve the filling efficiency. In addition, setting the intake/exhaust overlap period to a range of 0 to 20 degrees with respect to the rotation angle of the eccentric shaft improves charging efficiency and reduces the amount of dilution gas brought in to improve performance during low engine loads. This is preferable because misfires can be prevented.

(Effects of the Invention) As explained above, according to the present invention, in a side intake port type two-cylinder rotary piston engine, when the engine rotates at a high speed of 5000 to 7000 rpm,
Since the supercharging effect is obtained by the intake inertia effect between the cylinders and the individual intake pulsation effect of each cylinder, it is possible to achieve the supercharging effect by simply changing the design of the existing intake system without the need for a supercharger. With this configuration, it is possible to significantly increase the charging efficiency when the engine is under high load and high speed, thereby significantly and effectively increasing the output, thereby greatly contributing to the easy implementation of measures to improve engine output and cost reduction. It is.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall explanatory diagram, FIG. 2 is an overall schematic configuration 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 body. 3 is a graph 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, 4... Side housing, 5... Casing, 6... Rotor, 7... Eccentric shaft, 16... Main intake passage,
16a...first intake passage, 16b...second intake passage, 18...throttle valve, 20...communication passage, 21...expansion chamber.

Claims (1)

[Claims] 1. The interior of the casing, which is formed by a rotor housing with a two-bar trochoidal inner circumferential surface and a side housing with intake ports located on both sides of the rotor housing and having an intake passage opening, is arranged in a substantially triangular shape. In a two-cylinder rotary piston engine in which a shaped rotor is supported by an eccentric shaft and rotates planetarily, and each rotor has a phase difference of 180° at the rotation angle of the eccentric shaft, a. The opening period of the intake port. (b) An enlarged chamber with a communication passage that communicates the intake passages of each cylinder downstream of the throttle valve; (c) An engine operating at 5,000 to 7,000 rpm; The communication passage and its downstream are designed to propagate the compression waves generated in the intake passage when the intake port of one cylinder is closed at high engine speeds through the communication passage to the intake port of the other cylinder just before it is fully closed. The length of the passage between the intake ports of both cylinders formed by the intake passage is 1.31
- 1.83 m, d When the engine is running at a high speed of 5000 to 7000 rpm, the expansion liquid generated in the intake passage due to the start of intake at the intake port of each cylinder is reversed and reflected by the expansion chamber 2. The length of the intake passage from the enlarged chamber to the intake port of each cylinder is set to 0.35 to 0.63 m so that the next pulsating wave propagates to the intake port of each cylinder immediately before fully closing. Intake system for rotary piston engine.