JPH0331907B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine in which an intake passage is provided with a rotary timing valve that sets the opening timing of the intake passage.

(Prior Art) Recently, various engines have been proposed in which a rotary timing valve is provided in the intake passage of the engine, and the opening timing of the intake passage is set by the timing valve.

An example of an engine equipped with such a timing valve is a partially supercharged engine as shown in Japanese Utility Model Publication No. 86319/1983. That is,
In partial supercharging, supercharging is performed from the end of the suction stroke or the beginning of the compression stroke to the middle of the compression stroke.The timing of such supercharging is set, and the supercharging air is suddenly released at the time of opening. A rotary timing valve will be used to allow the introduction of

Incidentally, although rotary timing valves are suitable as this type of timing valve because of their simple structure, the following problems occur when using them. In other words, this valve is configured to open the supercharging passage when the opening provided in the rotating body coincides with the downstream side of the supercharging passage due to the rotation of the rotating body. When the rotational speed of the rotating body also increases, the time during which the passage is open becomes gradually shorter, so that the required amount of air cannot be supplied during high-speed operation of the engine, and the filling effect decreases.

(Object of the Invention) The present invention addresses the above-mentioned problems in the conventional art, and is directed to an intake system for an engine equipped with a rotary timing valve in the intake passage.
To variably control the opening timing of an intake passage opened and closed by the operation of the timing valve with a simple configuration. The purpose of this is to obtain the required amount of air filling in each operating range of the engine, particularly in the high-speed range.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention has the following structure. That is, basically, in an engine intake device in which an intake passage of the engine is provided with a timing valve that opens the intake passage at a predetermined timing, the timing valve is provided with a rotor having an opening; The intake passage is of a rotary type that opens the intake passage when the opening of the rotor coincides with the downstream opening of the intake passage, and the downstream opening of the intake passage facing the rotor is connected to the partition wall. A plurality of branch passages are defined by the engine, and a part of the plurality of branch passages is provided with a cutoff valve that is opened and closed depending on the operating mode of the engine. With such a configuration, the air filling amount can be set as desired according to the opening/closing of some of the branch passages by the shutoff valve.

Further, in the present invention, in order to ensure a prompt flow of intake air immediately after the shutoff valve opens, the shutoff valve has the following configuration. That is, the shutoff valve is of a rocking type that opens and closes by swinging around the central axis of operation, and the shutoff valve of the rocking type is such that the central axis of operation is centered on the shutoff valve. The valve is arranged to be offset from the center axis of the branch passage in which the valve is provided, and when the valve is opened, the end opposite to the offset operating center axis is displaced toward the downstream side of the branch passage. It is structured like this. With this configuration, when the cutoff valve opens, the intake air can smoothly flow through the branch passage provided with the cutoff valve without being obstructed by the cutoff valve as much as possible.

(Example) Hereinafter, an example in which the present invention is applied to a partially supercharged engine will be described based on the attached drawings.

In FIG. 1, 1 is an engine body, and in this embodiment, the engine body 1 rotates a crankshaft 5 as an engine output shaft via a continuous rod 4 by the reciprocating movement of a piston 3 in a cylinder 2. It is said to be a response type.

A main intake port 7, an exhaust port 8, and a supercharging port 9 are opened in the upper part of the combustion chamber 6 defined by the cylinder 2 and the piston 3, and the main intake port 7 is connected to a main intake valve 10. Accordingly, the exhaust port 8 is opened and closed by the exhaust valve 11 in synchronization with the rotation of the crankshaft 5 via a timing cam (not shown). Further, the supercharging port 9 is opened and closed by an auxiliary valve 12, and the auxiliary valve 12 synchronizes with the rotation of the crankshaft 5 by a timing cam (not shown).
The main intake valve 10 is opened immediately before its closing timing.
The valve is also closed during the compression stroke.

The main intake port 7 is connected to an air cleaner 14 via a main intake passage 13.
3 is connected to a carburetor 16 having a main throttle valve 15. In addition, the supercharging port 9
is connected to the air cleaner 14 via the supercharging passage 17.
A supercharger 18, a rotary timing valve 19, and a sub-throttle valve 20 are arranged in the supercharging passage 17 in this order from the upstream side. In the embodiment, the supercharger 18 is of a so-called supercharge type which is mechanically driven by the crankshaft 5 via a winding medium such as a timing belt or a chain (not shown); for example, a vane type. A positive displacement air pump is used. Further, the sub-throttle valve 15 is interlocked with the main throttle valve 15, and is opened when the throttle valve 15 reaches a predetermined opening degree or more. Furthermore, the timing valve 19
is mechanically driven by the crankshaft 5, and as shown in FIG. 2
The power is transmitted through a pulley 23 provided at 4.

The timing valve 19 will be explained in detail with reference to FIG. 2, which shows an example of a case where it is used for an in-line two-cylinder engine.In addition to the rotating shaft 24, the timing valve 19 has a casing 25 and a bottomed cylindrical rotor 26. It is a basic element. Each end of the rotating shaft 24 is rotatably supported by the casing 25 via a bearing 27 (the bearing on the right side in FIG. 2 is not shown), and one end (the left end in FIG. 2) is rotatably supported by the casing 25. , rotor 2
6 are integrated. The rotor 26 has communication ports 28 in its cylindrical side wall, spaced apart from each other in the axial direction and spaced apart in the circumferential direction, in a number corresponding to the number of cylinders (two in the embodiment). is opened, and two downstream passages 29 are formed in the casing 25 facing the cylindrical side wall of the rotor 26, which serve as supercharging passages 17 downstream of the rotor 26. . The downstream passages 29 are connected to each cylinder (each supercharging port 9) of the engine main body 1, and are formed at intervals in the axial direction of the rotor 26. The open end side of the bottomed cylindrical shape is always communicated with the supercharging passage 17 located on the upstream side, so that the communication port 28 is connected to the downstream passage 29 according to the rotation of the rotor 26. When they match, the supercharging passage 17 of the cylinder corresponding to this downstream passage 29 (communication port 28) is opened.

A downstream passage 2 immediately downstream of the rotor 26
9 is defined by a partition wall 30 into two branch passages 29A and 29B in the rotational direction of the rotor 26 (indicated by arrow A in FIG. 3). A shutoff valve 31 is disposed in one of the two branch passages 29A and 29B, which is on the front side in the rotational direction of the rotor 26. This cutoff valve 31 has its operating center axis 31a.
In the embodiment, a pair of valve plates 31 extend 180° opposite to each other in the radial direction from the operating center axis 31a.
It is said to be a butterfly type having 31c and 31c. The cutoff valve 31 is a diaphragm device 32
It is designed to be driven by The diaphragm device 32 includes an exhaust pressure chamber 32a, into which exhaust pressure from an exhaust passage connected to the exhaust port 8 of the engine body 1 is introduced via an exhaust pressure passage 33. . When this exhaust pressure is large, the diaphragm 32b presses the rod 32d toward the center in FIG. The shutoff valve 31 is opened by rotating the center shaft 31a clockwise in FIG. 3 (see arrow B in FIG. 3).

Here, the operation center axis 31a of the cutoff valve 31 is
is the central axis Y of the branch passage 29A in which this is provided.
In the embodiment, this offset direction is aligned with the axis X of the downstream passage 29.
The direction is the radially outer side of the rotor 26, that is, the front side in the rotational direction of the rotor 26. Further, when the shutoff valve 31 is moved from the closed position shown by the dashed line in FIG. , and is displaced toward the downstream side of the branch passage 29A.

Next, the operation of the above configuration will be explained.

First, when the main throttle valve 15 is under low load with a predetermined opening degree or less, the sub throttle valve 20 is closed, so intake air is supplied to the combustion chamber 6 only from the main intake port 7, and natural intake occurs. It will be done.

When the main throttle valve 15 is under a high load with a predetermined opening degree or more, the sub throttle valve 20 is opened, so in addition to the natural intake described above, combustion occurs from the supercharging port 9 from the end of the intake stroke to the middle of the compression stroke. Partial supercharging in which supercharging air is supplied to chamber 6 will be performed.

During the above partial supercharging, when the engine rotates at low speed, the exhaust pressure is small, so the shutoff valve 31 is closed, and therefore the opening timing of the timing valve 19 is delayed (see FIG. 4). Furthermore, when the engine rotates at high speed, the exhaust pressure increases, so the shutoff valve 31 opens, which causes the timing valve 1 to open.
9 will be opened earlier (see Figure 5).
That is, when the cutoff valve 31 is open, the opening timing of the timing valve 19, that is, the supercharging passage 17 is earlier than when it is not open, by the amount indicated by the angle β in FIG. become longer. Therefore, even though the rotation of the rotor 26 increases at high speeds, a sufficient amount of supercharging air is supplied to the combustion chamber 6.

Here, when the shutoff valve 31 opens, its operating central axis 31a is offset with respect to the central axis Y of the branch passage 29A, and the valve plate 31c at the end opposite to the offset direction is offset from the central axis Y of the branch passage 29A. Since the valve is displaced downstream, the shutoff valve 3
1 is prevented as much as possible from becoming a resistance to the supercharging air flowing through the branch passage 29A.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

Although the embodiment shows a case of so-called partial supercharging, it can also be applied to a case where supercharging air is supplied to the combustion chamber 6 simultaneously with the opening of the main intake valve 10 in the embodiment, so-called full supercharging. In this case, for example, the supercharger 18 can be connected to the intake passage 13 without providing the supercharging port 9 and the accompanying auxiliary valve 12.

As the fuel supply device, a fuel injection valve may be used instead of the carburetor 16.

The supercharger 18 may be provided with, for example, an electromagnetic clutch in its power transmission path, and the electromagnetic clutch may be disengaged to stop the supercharger 18 when the load is low.

The present invention is applicable not only to reciprocating engines but also to rotary piston engines.

The engine intake system according to the present invention can also be applied to a normal engine that does not perform supercharging.
That is, for example, while the opening timing of the intake passage is set using a timing valve, the intake valve (corresponding to the main intake valve in FIG. 1) can be made to function only as a shutoff valve. In this case, since the timing valve has the characteristic of being opened all at once compared to a lift-type intake valve, there are advantages such as improved filling efficiency.

The cutoff valve 31 may have a valve plate only on one side in the radial direction of the central axis of operation 31a.

Three or more downstream passages 29 may be provided along the rotational direction of the rotor 26, and some of them may be provided with cutoff valves 31 that open sequentially as the engine speed increases.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
While taking advantage of the advantages of rotary timing valves, it is possible to control the opening timing (opening period) according to the engine operating mode and supply the required amount of air to the engine according to the engine operating mode. .

In addition, the shutoff valve that adjusts the opening timing of the timing valve is designed so that it does not create passage resistance for the intake air, so it is possible to secure the necessary amount of air and change the amount of air according to the opening and closing of the shutoff valve. This is preferable in terms of improving the responsiveness of the system. Of course,
In order to reduce this passage resistance, it is only necessary to arrange the operating center axis of the swing-type shutoff valve and set the opening direction, so it can be done very easily.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the timing valve section along the direction of its rotation axis. FIG. 3 is a cross-sectional view showing the timing valve section along a direction perpendicular to its rotation axis. FIGS. 4 and 5 are diagrams showing timing valve opening timings (opening periods) according to the operating mode of the engine. 1: Engine body, 6: Combustion chamber, 10: Main intake valve, 12: Auxiliary valve, 13: Main intake passage,
17: Supercharging passage, 19: Timing valve, 2
4: Rotating shaft, 26: Rotor, 28: Communication port (timing valve opening), 29: Downstream passage, 2
9A, 29B: Branch passage (downstream opening), 3
0: partition wall, 31: cutoff valve, 31a: central axis of operation, X: central axis of downstream passage, Y: central axis of branch passage, α: offset amount.

Claims (1)

[Scope of Claims] 1. An intake system for an engine in which an intake passage of the engine is provided with a timing valve that opens the intake passage at a predetermined timing, wherein the timing valve includes a rotor having an opening; The intake passage is of a rotary type that opens the intake passage when the opening of the rotor coincides with the downstream opening of the intake passage, and the downstream opening of the intake passage facing the rotor is connected to the partition wall. A plurality of branch passages are defined by a plurality of branch passages, and a cutoff valve is provided in a part of the plurality of branch passages, and the cutoff valve is opened and closed depending on the operating mode of the engine, and the cutoff valve is oscillated around the central axis of operation. The shutoff valve is of a rocking type that opens and closes by movement, and the rocking type shutoff valve has a center axis of operation that is offset from a central axis of a branch passage in which the shutoff valve is installed. An intake device for an engine, characterized in that the end opposite to the offset operating center axis is displaced toward the downstream side of the branch passage when the opening operation is performed. .