JPH0676778B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an engine, which uses an inter-cylinder interference effect to supercharge intake air.

(Prior Art) It has been conventionally known that an engine output is improved by supercharging intake air by utilizing an inter-cylinder interference effect in an engine (for example, JP-A-59-70833).

The inter-cylinder interference effect is the compression wave generated in the intake passage due to the inertia of the intake itself when the intake port of one of the predetermined two cylinders in the engine having a plurality of cylinders is closed, or the intake air A compression wave generated when the high-pressure exhaust gas remaining in the working chamber when the port is opened flows backward to the intake passage side and interferes with the intake air in the intake passage, causing a compression wave to the intake port portion of the other cylinder. It is a phenomenon that acts at the end of the opening period and forcibly pushes the intake air into the working chamber.

By the way, since the inter-cylinder interference effect is brought about by the propagating action of the pressure wave in the intake passage provided between the pair of cylinders as described above, the inter-cylinder interference effect is utilized to the maximum extent. In order to accurately apply the high-level pressure wave generated on one cylinder side to the intake port portion of the other cylinder and at the end of the opening period thereof, the intake passage length between the intake ports of both cylinders ( In other words, it is necessary to properly set the pressure wave propagation time. That is, since the temporal operation phase difference between both cylinders becomes short during high-speed operation of the engine (in other words, it is necessary to complete the inter-cylinder interference action in a short time). On the other hand, the operating phase difference between the two cylinders becomes long when the engine is operating at low speed (in other words, it is necessary to complete the inter-cylinder interference action over a relatively long period of time). Therefore, it is necessary to set the length of the intake passage longer.

As described above, in order to obtain the inter-cylinder interference effect in a wider operating region of the engine, it is necessary to change the intake passage length between the intake ports of both cylinders according to the rotation speed of the engine.

From this point of view, as an example of the one in which the intake passage length is changed according to the engine speed, for example, Japanese Utility Model Publication No. Sho 59-188027 (this one is intended for the intake inertia effect rather than the inter-cylinder interference effect. As described in (1), the intake passage is configured with a spiral double passage,
It is known that the intake passage length is made variable by rotating both of them relatively. However, this method is not preferable because the passage structure becomes complicated, and the intake passage for obtaining the inter-cylinder interference effect is obtained. As a result, the structure itself is unsuitable (that is, it is necessary to connect the intake ports of the two cylinders to each other in order to perform the inter-cylinder interference, but in the passage configuration as in this known example, the intake upstream side It is not easy to connect the two cylinders to each other because the vortex chamber is formed in the.

In addition to this, for example, an intake passage having a long passage and an intake passage having a short passage are provided independently of each other between the intake ports of both cylinders.
It is conceivable to selectively use one of the passages, but in such a case, there is a problem that the passage structure becomes complicated and large-sized, which is not preferable.

On the other hand, in order to effectively use the inter-cylinder interference effect,
It is important to suppress the dispersion / attenuation of the pressure wave propagating in the intake passage as much as possible. Therefore, it is necessary to fully consider this point when designing the intake passage. It is recognized that such consideration is rarely made.

The intake inertia effect described in Japanese Utility Model Publication No. 59-188027 mentioned above means that when the intake port of the engine is opened,
The negative pressure wave generated in the intake passage due to the suction force of the piston propagates in the intake passage toward the upstream side of the intake air, is inverted in the volume portion (atmosphere open end) of the surge tank or the like, and becomes a positive pressure wave. This positive pressure wave propagates in the intake passage from the volume side toward the intake port side and acts on the intake port section, forcing the intake air into the working chamber of the engine (supercharging).

(Object of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned prior art. In an engine that utilizes the cylinder interference effect, the inter-cylinder interference effect can be achieved with a simple passage configuration. Moreover, it is an object of the present invention to provide an intake system for an engine that can be obtained in a wider operating range of the engine.

(Means for Achieving the Purpose) As means for achieving the above object, the present invention has a plurality of cylinders that operate with a predetermined phase difference from each other, and between two predetermined cylinders among those cylinders. In an engine configured to mutually perform supercharging of intake air due to an inter-cylinder interference effect, a first intake passage and a second intake passage respectively connected to respective intake ports of predetermined two cylinders that mutually perform supercharging. Of the intake passages are joined to each other in an opposed state substantially coaxially on the intake upstream side to form a first merging portion, and the first merging portion is provided between the two intake passages in accordance with the operating state of the engine. Is provided with a control valve for communicating with or shutting off the communication, and further with a first branch passage communicating with the first intake passage and a second intake passage communicating with the first intake passage from both sides of the control valve of the first merging portion. Follow the second branch passage This is branched and formed, and these are joined together on the upstream side of the intake air to form a second joining portion, and the second joining portion is communicated with the atmosphere side.

(Operation) According to the present invention, by the above means, (1) two intake passages, which communicate with the intake ports of a pair of cylinders that exchange pressure waves with each other, face each other substantially coaxially at the first junction. Since they are merged in a state, energy attenuation or dispersion at the time of pressure wave interference is small, and inter-cylinder interference is performed more efficiently. (2) Only the opening / closing operation of the control valve provided in the first merging portion Thus, the passage length of the intake passage that contributes to the inter-cylinder interference action can be set to be short during the high-speed operation of the engine and long during the low-speed operation of the engine, and the inter-cylinder interference action can be effectively used in a wider operation region of the engine. (3) A control valve is provided at the first confluence portion which is concentrically converging in a confronting state, and a control valve is provided at both sides of the control valve at the second confluence portion. Since the two merging branch passages are respectively branched, the dead volume in the control valve portion is as small as possible. Therefore, the control valve is closed to cause the inter-cylinder interference via the second merging portion. In this case, the attenuation / dispersion of the pressure wave can be suppressed as much as possible.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

(Structure) FIGS. 1 and 2 show a two-rotor rotary piston engine Z for an automobile equipped with an intake device according to an embodiment of the present invention.
It is shown. This rotary piston engine Z
An engine casing configured by connecting a pair of side housings 2 and 3, two rotor housings 4 and 5 having a two-section trochoidal inner peripheral surface, and one intermediate housing 6 in a predetermined order. 1 is provided. In the two trochoid spaces 9 and 10 respectively formed on both sides of the intermediate housing 6 in the engine casing 1, planets are provided around an eccentric shaft 11 penetrating the engine casing 1 in its axial direction. Rotating rotors 7 and 8 are fitted in the rotors 7 and 8, respectively.
A first cylinder E ₁ and a second cylinder E ₂ having three working chambers 9A, 9B, 9C and 10A, 10B, 10C on the three sides of are formed.

In each of the trochoid spaces 9 and 10 of the _two cylinders E ₁ and E ₂ of the rotary piston engine Z, an exhaust port 24 and three intake ports, that is, a sliding surface 6a of the intermediate housing 6 are provided for each of them. The first intake port 21 opening to the side and the sliding surface 2a of the side housing 2 (or 3)
A second intake port 22 and a third intake port 23 that open upward (or 3a) are formed. Each of these three intake ports 21, 22, 23 is selectively used by the valve operation on the side of the intake passage assembly 30 (described later in detail) connected thereto. That is, only the first intake port 21 of each of the cylinders E ₁ and E ₂ is valid in the light load operation region of the engine, and the first intake port 21 and the second intake port 21 are effective in the medium load operation region of the engine. Two of the ports 22 are made effective, and all three intake ports 21, 22, 23 are made effective in the high load operation region of the engine.

Further, in this embodiment, the three intake ports 21,2
The closing timings of the second and the second intake ports 22 are set to be sequentially closed in the order of the second intake port 22 → the first intake port 21 → the third intake port 23. Therefore, of the three intake ports 21, 22, 23 in the medium-load operating region of the engine, the second intake port 22 and the third intake port 23 in the high-load operating region of the engine, respectively. It will be closed at the end. Therefore, in order to make the most effective use of the inter-cylinder interference effect described above, the length of the intake passage that contributes to the inter-cylinder interference effect should be set to a value immediately before the closing of the third intake port 23 during high-load operation of the engine. To the third intake port 23
The pressure wave acts on a portion of the second intake port 22, and the pressure wave acts on the portion of the second intake port 22 just before the second intake port 22 is closed when the engine is operating under medium load. .

Intake passage assembly 30 includes a first passage unit 31 which is connected in common to the two cylinders E _1, E each first intake ports 21, 21 of _2, two-cylinder E _1, the E ₂ Each of the second intake ports 22, 22 and the second passage unit 32 commonly connected to each of the third intake ports 23, 23 are configured to be joined on the intake upstream side. The merging portion 39 of the first passage unit 31 and the second passage unit 32 is formed so as to have a volume capable of functioning as a reversal portion of the pressure wave due to the intake inertia, and will be described below. This confluence is referred to as the volume 39. An air flow meter 15 and an air cleaner 14 are provided upstream of the volume 39.

The first passage unit 31 is provided with a first throttle valve 41, which is opened and closed in conjunction with an accelerator pedal (not shown) throughout the entire operating range of the engine, at a position immediately downstream of the volume 39, and the downstream thereof. The ends are branched into two branches and are connected to the first intake ports 21, 21 of the cylinders E ₁ , E ₂ , respectively. The passage length of the first passage unit 31 is set as follows. That is, the first
The supercharging effect via the intake port 21 of the engine is expected in the light load operation region of the engine.
The passage length of the passage unit 31 may be set so that the inter-cylinder interference effect and the intake inertia effect can be effectively used in the light load operation region. Therefore, in this embodiment, from the first intake port 21 of the first cylinder E ₁ to the second cylinder
Set the first length between cylinders interference effects such as to obtain long during low-speed operation of the engine in a substantially U-shaped passage portion leading to the intake port 21 of the E _2, also each of the cylinders E _1, E The length of the passage extending from each of the first intake ports 21 of No. _{2 to} the volume 39 is set such that the intake inertia effect can be obtained during low speed operation.

The second passage unit 32 includes a first intake passage 33 commonly connected to the second intake port 22 and the third intake port 23 of the first cylinder E ₁ , and a second cylinder E ₂ Second intake port of
2nd commonly connected to 22 and 3rd intake port 23
And the intake passage 34 of the first converging section 35 are joined together in a substantially coaxial manner so as to face each other to form a first confluence section 35.
43 is installed. The first control valve 43 is designed to be opened only in a high speed / high load operation range (for example, 5000 to 7000 rpm) of the engine, and to be opened and maintained in other operation ranges. , Is controlled by a diaphragm type actuator 47 which operates according to the exhaust pressure of the engine.

Further, from both sides of the first merging portion 35 of the first control valve 43, a first branch passage 36 communicating with the first intake passage 33 and a second branch passage 36 communicating with the second intake passage 34 are formed. 2 branch passages
37 are branched. This first branch passage
36 and the second branch passage 37 are joined together on their upstream sides to form a second joining portion 38, which is communicated with the volume portion 39. A second throttle valve 42 that opens only in the medium / high load operating region of the engine is mounted between the second merging portion 38 and the volume portion 39.

Further, the communicating portion of the first intake passage 33 to the third intake port 23 and the third intake port 23 of the second intake passage 34.
The second control valve 44, which operates to open the valve to the third intake port 23 only in the high-load operation of the engine and to cut off the communication to the third intake port 23 in the other operating regions.
And a third control valve 45 are mounted respectively. still,
Both the second control valve 44 and the third control valve 45 are controlled by a diaphragm type actuator 46 which operates by receiving the exhaust gas pressure of the engine.

The passage length of the second passage unit 32 is also set so that the intake inertia effect and the inter-cylinder interference effect can be obtained as in the case of the first passage unit 31. That is, the first
Through the intake passage 33 and the second intake passage 34 of the first cylinder E ₁
Connecting the second intake port 22 and the third intake port 23 of the second cylinder E ₂ to the second intake port 22 and the third intake port 23 of the second cylinder E ₂ (hereinafter, referred to as the first pressure wave propagation path). The length of 51) is the high-speed operating range of the engine (for example, 5000 to
(7000 rpm), the length is set so that the inter-cylinder interference effect can be maximally utilized (in other words, the length at which the supercharging action is obtained immediately before the third intake port 23 is closed). In addition, the second intake port 22 and the third intake port 23 of the first cylinder E ₁ and the second intake port 22 and the third intake port 23 of the second cylinder E ₂ are connected to the first intake passage 33. , The length of the passage connecting the first branch passage 36, the second branch passage 37, and the second intake passage 34 (hereinafter, referred to as the second pressure wave propagation path 52) is the middle speed of the engine. Operating range (for example, 2000-
At 4000 rpm), the length is set to maximize the inter-cylinder interference effect.

Also, from the second intake port 22 and the third intake port 23 of the first cylinder E ₁ to the first intake passage 33 and the first branch passage 36.
Via the through passages R _1, a second cylinder E from the second intake port 22 and the third intake port 23 of the ₂ second intake passage 34 and the second branch passage 37 leading to the volume 39 The above volume 39
The passage R ₂ leading to is set to such a length that the intake inertia effect can be effectively used in the medium speed operation range of the engine. In this case, the passage length is the same on both the first cylinder E ₁ side and the second cylinder E ₂ side (the lengths of both are shown in FIGS. 1 and 1 for convenience of drawing. Are drawn differently).

(Operation and Its Action) Next, the operation of the rotary piston engine Z and its action will be described.

First, in the high load operation region of the engine, both the first throttle valve 41 and the second throttle valve 42 are opened in response to the depression of the accelerator pedal, and the second control valve 44 and the third control valve 42 are operated. Both 45 are held open. Further, the first control valve 43 is held open, and the first intake passage 33 and the second intake passage 34 are communicated with each other via the first confluence portion 35, so that the first pressure wave propagation is performed. Route 51 is valid. Therefore, in this operating state, the inter-cylinder interference action is performed between the first cylinder E ₁ and the second cylinder E ₂ via the first pressure wave propagation path 51, and the intake supercharging action is performed. Will be realized. At this time, since the first intake passage 33 and the second intake passage 34 merge in a state where they are opposed to each other substantially coaxially, pressure interference between the cylinders E ₁ and E ₂ (that is, exchange of pressure waves). Is performed efficiently with almost no damping or dispersion, and a high level of supercharging effect is obtained.

On the other hand, in the medium load operation range of the engine, the first throttle valve 41 and the second throttle valve 42 are opened, which is similar to the above high speed / high load operation range. Control valve 43, second control valve 44 and third
The control valve 45 is kept closed. That is, in this operating region, the first pressure wave propagation path 51 is invalid, and the second pressure wave propagation path 52 is valid instead. Therefore, in this operating region, the inter-cylinder interference action and the intake inertia action are performed via the second pressure wave propagation path 52, and a higher level supercharging effect is realized by the synergistic action of both. .

On the other hand, in the low load operation region of the engine,
Of the three intake ports 21, 22, 23 of E ₁ and E ₂ , only the first intake port 21 is valid. Therefore, in this operating region, the inter-cylinder interference action and the intake inertia action are performed only on the first passage unit 31 side, and a high level supercharging effect is realized.

That is, according to this intake system, the effect of supercharging the intake air can be obtained in a wide operating range from the low load operating range to the high load operating range of the engine.

It should be noted that the above-mentioned embodiment is a case where the present invention is applied to a rotary piston engine, but the present invention is not limited to this embodiment and can be widely applied to general engines including reciprocating engines. Needless to say.

(Effects of the Invention) An intake system for an engine according to the present invention has a plurality of cylinders that operate with a predetermined phase difference from each other, and intake of intake air due to an inter-cylinder interference effect between two predetermined cylinders among these cylinders. In an engine configured to perform supercharging action, a first intake passage and a second intake passage, which are respectively connected to respective intake ports of a predetermined two cylinders that perform the supercharging action, are provided on the intake upstream side thereof. A control valve for forming a first merging portion by merging the first and second merging portions in a substantially coaxial manner so as to face each other and for connecting or disconnecting the two intake passages to each other in accordance with the operating state of the engine is formed in the first merging portion. A first branch passage communicating with the first intake passage and a second branch passage communicating with the second intake passage from both sides of the control valve at the first merging portion. And this is the intake upstream side In (1), the second merging portion is formed by merging with each other and the second merging portion is communicated with the atmosphere side.

Therefore, in the engine intake system of the present invention, (1) the two intake passages that respectively communicate with the intake ports of the two cylinders that exchange pressure waves with each other face each other substantially coaxially at the first merging portion. Since they are merged in a state, energy attenuation or dispersion at the time of pressure wave interference is small, and inter-cylinder interference is performed more efficiently. (2) Only the opening / closing operation of the control valve provided in the first merging portion Thus, the passage length of the intake passage that contributes to the inter-cylinder interference can be set to be short during high-speed operation of the engine and long during low-speed operation of the engine, and the inter-cylinder interference can be effectively used in a wider operating region of the engine. (3) The length of the intake passage that contributes to the inter-cylinder interference action can be adjusted according to the operating state of the engine by (3) opening and closing the control valve provided in the first merging portion. Since it can be changed to, the passage structure is simpler than that of a structure in which a passage for high speed and a passage for low speed which are independent from each other are provided and these passages are selectively used. Is advantageous in terms of downsizing and cost reduction. (4) A control valve is provided at the first converging portion which is concentrically converging in a confronting state, and a second confluence is provided from both sides of the control valve. Since the two branch passages that join each other are formed in a branched manner, the dead volume in the control valve portion is as small as possible. Therefore, the control valve is closed and the inter-cylinder interference is generated via the second joining portion. When it is performed, the attenuation and dispersion of the pressure wave is suppressed as much as possible, and a high level of supercharging effect can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a rotary piston engine equipped with an intake device according to an embodiment of the present invention, and FIG. 2 is II- of FIG.
FIG. 2 is a vertical sectional view of a main part of II. 1 …… Engine casing 2,3 …… Side housing 4,5 …… Rotor housing 6 …… Intermediate housing 7,8 …… Rotor 9,10 …… Trochoid space 11 …… Eccentric shaft 21 …… First Intake port 22 ...... Second intake port 23 ...... Third intake port 24 ...... Exhaust port 33 ...... First intake passage 34 ...... Second intake passage 35 ...... First merging portion 36 ...... First branch passage 37 ...... Second branch passage 38 ...... Second merging portion 43 ...... Control valve E ₁ ...... First cylinder E ₂ ...... Second cylinder

Claims (1)

[Claims] 1. A plurality of cylinders that operate with a predetermined phase difference from each other, and a predetermined two cylinders among these cylinders mutually perform supercharging action of intake air due to an inter-cylinder interference effect. In the engine, the first intake passage and the second intake passage, which are respectively connected to the intake ports of the predetermined two cylinders that perform mutual supercharging action, are opposed to each other substantially coaxially on the intake upstream side. A first merging portion is formed by merging, and a control valve is provided in the first merging portion for communicating or blocking communication between the two intake passages according to the operating state of the engine, and the first merging portion is further provided. A first branch passage communicating with the first intake passage and a second branch passage communicating with the second intake passage from both sides of the control valve, and these are formed on the intake upstream side with respect to each other. And join the second An intake device for an engine formed and the merging portion of the second the parts, characterized in that communicates with the atmosphere side.