JPH086600B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine having a rotary valve in an intake passage.

(Prior Art) Conventionally, there are various known engine intake devices in which a rotary valve that opens and closes in synchronization with the engine is provided in the intake passage of the engine, and the intake start timing and the income end timing are adjusted by the rotary valve. Has been. For example, in the device disclosed in Japanese Examined Patent Publication No. 58-55329, a rotary valve is provided downstream of the supercharger of an engine having a supercharger in the intake passage, and the closing timing of this rotary valve is determined from the closing timing of the intake valve. By increasing the speed and adjusting the opening / closing timing, knocking is prevented under high supercharging pressure and high thermal efficiency is ensured.

By the way, various types of rotary valves provided in the intake passage are known, and as one type, a rotary valve having an opening for supplying intake air to each cylinder is provided on the circumferential surface of a cylindrical valve body. There is an axial flow type in which intake air is introduced from one end of the body. When such an axial flow type rotary valve is used, a pressure fluctuation occurs in the opening and a passage inside the valve body communicating with the opening due to the opening and closing operation thereof. Regarding the influence of the pressure fluctuation on the opening, Conventionally, no attention has been paid.

Note that, for example, when the intake port opening to the combustion chamber and the intake expansion chamber are connected by a passage for each cylinder, there is a structure in which the fluctuation of intake pressure is used to give a dynamic effect. Are known. However, when interposing the rotary valve in the intake passage as described above, particularly in the axial flow type rotary valve having a plurality of openings corresponding to each cylinder on the circumferential surface of the cylindrical valve body, each of the intake valve from the intake introduction side end Due to the preconception that it is difficult to affect the pressure fluctuations equally to each opening because the length to the opening is different, it is necessary to have an effective dynamic effect for the above openings. There was nothing I did.

(Object of the invention) In view of such circumstances, the present invention effectively gives a dynamic effect to the opening of the axial flow type rotary valve provided in the intake passage, and thereby improves the charging efficiency of the engine intake air. A device is provided.

(Structure of the Invention) The present invention is an intake system for an engine, wherein a rotary valve that opens and closes in synchronization with the engine is provided in an intake passage of the engine, and the rotary valve is provided to each cylinder on a circumferential surface of a cylindrical valve body. It is an axial flow type that has an opening for supplying intake air and introduces intake air from the end of the valve body, and an intake expansion chamber is provided in the intake passage upstream of this rotary valve. The length of the passage over which the pressure wave propagates for one round trip of this passage is the time from the negative pressure wave generation timing in the middle of the effective valve opening period of the rotary valve at the specific engine speed to the end of the effective valve opening period. It is set to correspond.

With this configuration, the pressure wave propagating from the opening of the rotary valve and reflected by the intake expansion chamber and the end of the passage in the rotary valve effectively acts on the opening, and the intake air is supplied from the opening by the dynamic effect. The action is enhanced.

The effective valve opening timing is a period in which both the rotary valve and the intake port are opened and the intake air is substantially supplied.

(Embodiment) FIG. 1 shows a first embodiment of the present invention. In this embodiment, the device of the present invention is applied to a 4-cylinder 4-cycle reciprocating engine. In this figure, 1 is the engine body,
Reference numeral 2 denotes each cylinder of the engine body 1, and an intake port 3 and an exhaust port 4 are opened in a combustion chamber of each cylinder 2, and the intake port 3 and the exhaust port 4 are intake valves and exhaust valves (these are not shown). Are opened and closed at predetermined timings. Exhaust port 4 of each cylinder 2
Is connected to the exhaust manifold 5.

A rotary valve 6 that opens and closes in synchronization with the engine is provided in an intake passage communicating with the intake port 3. This rotary valve 6 has a cylindrical valve body 9 rotatably supported in a bulce case 7 via a bearing 8.
And has a plurality of openings 10 for supplying intake air to each cylinder 2 on the peripheral surface of the valve body 9 and an intake port 11 for intake air on one end side of the valve body 9, which is an axial flow type. The other end of the valve body 9 is closed. The valve body 9 includes a pulley 12 connected to a shaft 9a of the valve body 9 and a crankshaft 13 of an engine.
It is interlocked with the crankshaft 13 so as to rotate at a rotation speed of 1/2 of the engine rotation speed, via a transmission mechanism including a pulley 14 connected to the pulley 14 and a timing belt 15 wound around them. Further, the valve case 7 is formed with an outlet port 7a that communicates with the intake port 3 for each cylinder 2 through the intake passage 16 for each cylinder. In addition,
Although not shown in the figure, an advance mechanism for adjusting the opening / closing timing is provided between the shaft 9a of the valve body 9 and the transmission mechanism so that the opening / closing timing of the rotary valve 6 is changed according to the engine speed. You may keep it.

Further, an intake expansion chamber 20 is provided in the intake passage upstream of the rotary valve 6, and the intake intake port 11 of the rotary valve 6 communicates with the intake expansion chamber 20. An air cleaner 22, an air flow meter 23, and a throttle valve 24 are arranged in an intake passage 21 upstream of the intake expansion chamber 20.

The length l of the passage extending from the intake expansion chamber 20 to the closed end of the rotary valve 6 is determined by the time during which the pressure wave propagates through one round trip of this passage at a specific engine speed. It is set to correspond to the time from the negative pressure wave generation timing in the middle of the effective valve opening period to the end of the effective valve opening period.

FIG. 2 shows the opening area of the rotary valve 6 (line A) and the opening area of the intake port 3 by the intake valve (line B) for one cylinder. The opening timing RO of the rotary valve 6 is The closing timing RC is set to be later than the opening timing IO, and the closing timing RC of the rotary valve 6 is set to be substantially the same as or later than the closing timing IC of the intake valve. In the apparatus of this embodiment as described above, the opening timing of the rotary valve 6 is
The intake air supply to the combustion chamber is substantially started from RO, and an effective valve opening period θ is provided from this time to the closing time of the intake valve or the rotary valve 6. The pressure fluctuation in the vicinity of the opening 10 of the rotary valve 6 during the effective valve opening period θ is as shown in FIG. 3, and a negative pressure wave is generated at a predetermined timing in the middle of the effective valve opening period. Then, by delaying the opening timing of the rotary valve 6, a large negative pressure wave is obtained due to the rapid pressure drop after the rotary valve is opened, and if the inverted positive pressure wave is effectively used, the so-called delayed opening inertia effect is obtained. It can be expected to improve the filling efficiency.

In this case, especially from the intake expansion chamber 20 to the rotary valve 6
By setting the passage length l to the closed end of the inside as described above, each opening of the rotary valve 6
Even if the distances of the 10 from the intake expansion chamber 20 are different from each other, the reverse positive pressure wave is effectively applied to each opening 10, and the dynamic effect can be equally exerted to each cylinder 2.
This action will be described with reference to FIG.

FIG. 4 shows pressure propagation in the passage extending from the intake expansion chamber 20 to the inside of the rotary valve 6. In this figure, the downward convex waveform is a negative pressure wave Wn, and the upward convex waveform is a positive pressure wave. It represents Wp. As shown in this figure, the negative pressure wave generated in the opening 10 of the rotary valve 6 during the effective opening period.
Wn moves left and right in the figure in the passage. Of these, the one to the left of the figure is propagated as shown by arrow a, that is,
First, the positive pressure wave Wp is inverted at the opening end to the intake expansion chamber and is reflected to the right, and when it propagates to the end of the passage, the positive pressure wave Wp is reflected to the left as it is. Intake expansion chamber 20
The pressure wave that has reached the original position of the opening 10 after being reflected by the end of the passage and the end of the passage travels the distance of one round trip of this passage. In addition, the negative pressure wave from the opening 10 to the right in the figure
Wn is propagated as shown by an arrow b, that is, it is first reflected as a negative pressure wave at the end of the passage and then reflected as an inverted positive pressure wave Wp at the opening end to the intake expansion chamber 20, and then the original opening 10 is formed.
When the pressure wave reaches, the pressure wave also travels a distance corresponding to one round trip of the passage. Therefore, these inverted positive pressure waves Ep
Simultaneously act on the opening 10, and when the positive pressure wave increases the pressure of the opening 10 at the end of the effective valve opening period, the opening 10
The intake air supply amount from is increased, and the charging efficiency is improved.

This condition is obtained when the relationship between the passage length (equivalent pipe length) l and the engine speed N is N = 60/2 × a / 2l × θ / 360 (a is the speed of sound) Therefore, according to the setting of the passage length l, a dynamic effect can be obtained in the rotational speed range that satisfies the above conditional expression and in the rotational speed range in the vicinity thereof. In particular, since the distance from the intake expansion chamber 20 to the opening 10 is not related to this condition, the same dynamic effect can be obtained at any opening 10 of the rotary valve 6.

FIG. 5 shows a second embodiment of the present invention, which is applied to a 6-cylinder 4-cycle reciprocating engine. Also in this figure, the rotary valve 30 provided in the intake passage is an axial flow type, and rotates in conjunction with the crankshaft 13 in the valve case 41 having the outlet port 41a communicating with the intake passage 46 for each cylinder. A cylindrical valve body 42 is accommodated,
An opening 43 for supplying intake air to each cylinder 2 is arranged on the peripheral surface thereof, but in order to avoid pressure wave interference between the openings,
The inside of the valve body 42 has a partition wall 44 provided in the center thereof.
Are divided into passages leading to the openings 43 for the first to third cylinders and passages leading to the openings 43 for the fourth to sixth cylinders. Then, intake air intake ports 45 are formed at both ends of the valve body 42, and a pair of intake air expansion chambers 47 are connected to the respective intake air intake ports 45. The intake passage 48 leading to the chamber 47 joins.

Also according to this embodiment, the rotary valve 40 is opened and closed at a predetermined timing as in the first embodiment, and
Each pair of passages from each intake expansion chamber 47 to the partition wall 44 inside the valve body 42 of the rotary valve 40 is set to a predetermined length as in the first embodiment, so that each opening
The same dynamic effect can be applied to 43, and the filling efficiency can be increased.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, a two-cylinder rotary piston engine is used as an engine, and a supercharger 70 is provided in the intake system in addition to the main intake passage 57. The supercharging passage 58 provided is formed, and an axial flow type rotary valve 60 is provided in the supercharging passage 58 downstream of the supercharger 70.

That is, each cylinder 52 of the engine main body 51 is equipped with a rotor 53 that makes a planetary rotational movement, a working chamber 54 is partitioned and formed, and a main intake port 55 and a supercharging port 56 are provided at predetermined locations.
Are formed, and the ports 55 and 56 are opened and closed as the rotor 53 rotates. And each cylinder
The main intake passage 57 is connected to the main intake port 55 of 52, while the supercharging passage 58 is connected to the supercharging port 56.

The rotary valve 60 provided in the supercharging passage 58 has a cylindrical valve body in the valve case 61 that is interlocked with the engine output shaft.
62 has an opening 63 for supplying intake air to each cylinder 52 on the peripheral surface of the valve body 62, and also has an intake port at one end of the valve body 62.
An outlet port formed in the valve case 61 having 64.
61a communicates with the supercharging port 56 of each cylinder 52 via the supercharging passage 66 for each cylinder. An intake expansion chamber 67 communicating with the intake introduction port 65 is provided upstream of the rotary valve 60, and a supercharger 70 driven by an engine is provided in a supercharging passage 58 upstream of the intake expansion chamber 67. , A relief passage 71 for relieving excess supercharged air, and a throttle valve for the main intake passage 57.
A control valve 73 is provided which opens when the opening of 72 exceeds a predetermined opening.

In the structure of this embodiment, in order to prevent the supercharged air from flowing back into the main intake passage 57, the rotary valve 60 is provided so as to supply the supercharged air to the working chamber 54 from the end of the intake stroke to the compression stroke. The opening / closing timing is set. Also in this case, by setting the length of the passage extending from the intake expansion chamber 67 to the inside of the rotary valve 60 as described above, in addition to the supercharging effect by the supercharger 70, the filling efficiency is improved by the dynamic effect. It is further enhanced.

The present invention can be applied to various intake devices including a rotary valve in addition to the above-described embodiments. For example, a supercharger is provided in a single intake passage while maintaining a high supercharging pressure. An intake device with a rotary valve whose closing time is set earlier than the intake port to prevent knocking in the intake passage downstream of the turbocharger, or an intake device with a rotary valve to reduce pumping loss when the load is low, etc. Also in this case, by applying the present invention, in addition to the action of the rotary valve which is inherent in these devices, a dynamic effect can be provided at the time of high load.

(Advantages of the Invention) As described above, the present invention provides the intake expansion chamber upstream of the axial flow type rotary valve, and defines the passage extending from the intake expansion chamber to the inside of the rotary valve at the end of the passage on the intake expansion chamber side. Since the pressure liquid reflected at the end of the valve and the end of the passage is set to effectively act on the intake valve opening of the rotary valve, the pressure supply inside the rotary valve is used to make the intake supply amount from the opening. It is possible to increase the charging efficiency and increase the filling efficiency, and in particular, even if the cylindrical valve body has a plurality of openings corresponding to each cylinder on the circumferential surface, the same dynamic effect can be given to each.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a view showing opening / closing timings of an intake valve and a rotary valve, FIG. 3 is a view showing pressure fluctuations near an opening of the rotary valve, FIG. 4 is an explanatory view showing a pressure propagation state, FIG. 5 is a schematic sectional view showing a second embodiment, and FIG. 6 is a schematic sectional view showing a third embodiment. 1,51 …… Engine body, 2,52 …… Cylinder, 6,40,60 …… Rotary valve, 9,42,62 …… Cylindrical valve body, 10,43,63 ……
Opening, 11,45,64 ... Intake inlet, 20,47,67 ... Intake expansion chamber.

Claims (1)

[Claims] 1. An intake system for an engine, comprising a rotary valve that opens and closes in synchronization with the engine in an intake passage of the engine. The rotary valve is used to supply intake air to each cylinder on a circumferential surface of a cylindrical valve element. Along with the axial flow type that has an opening to introduce intake air from the end of the valve body, an intake expansion chamber is provided in the intake passage upstream of this rotary valve, and the length of the passage from this intake expansion chamber to the inside of the rotary valve is increased. That is, the time for the pressure wave to travel one round trip through this passage corresponds to the time from the negative pressure wave generation timing in the middle of the effective valve opening period of the rotary valve at the specific engine speed to the end of the effective valve opening period. The intake system of the engine, which is set to.