JPS60240822A - Suction system for engine - Google Patents

Abstract

PURPOSE:To secure the inertia effect of intake air ranging from the low rotation region to high rotation region of an engine by varying the volume of intake passage on the lower course of a valve which opens and closes in accordance with the operating condition of said engine depending on the engine speed. CONSTITUTION:Closing valves 10, 11 are provided on both upper and lower course sides of a secondary intake passage 4 which is connected to the combustion chamber 3 of an engine E, respectively. The closing levers 13, 14 of the closing valves 10, 11 are connected to actuators 17, 18 respectively, and opening operation signals P1, P2 are fed from a drive control circuit 19 to the actuators 17, 18 respectively. In a rotation region in which, e.g., the number of revolution of the engine E is lower than a first number of revolution N1 which is set as the upper limit of the low rotation region, the output of a first comparator 21 in a drive control circuit 19 is defined as high, while the output of a second comparator 22 is defined as low. And, the opening operation signal P1 is outputted from the first drive circuit 23, and applied to the actuator 17 via an OR circuit, permitting only the closing valve 10 on the lower course side to open.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an engine which has a plurality of intake passages opening into a combustion chamber, and at least one intake passage is provided with an on-off valve that opens and closes depending on the operating state of the engine. This invention relates to an air intake device.

(Prior Art) This type of engine intake system has been well known.

In general, the intake efficiency of an engine is controlled by dimensions such as the length of the intake passage, the cross-sectional area per passage, and the volume of the combustion chamber, and changes depending on the engine speed. This phenomenon is understood through analysis of pressure oscillations within the intake pipe and is generally referred to as the dynamic effect of intake air.

One example of this type of dynamic effect is the inertial effect. This inertial effect is caused by a positive pressure wave being sucked into the combustion chamber at once during the intake stroke when the natural frequency determined by the dimensions of the intake passage and the frequency of intake air determined by the engine speed satisfy the tuning condition. Therefore, it refers to the effect that maximizes filling efficiency or suction efficiency.

Conventionally, in order to ensure this kind of intake inertial effect over a wide range of engine speeds, at least one of the two intake passages having approximately the same cross-sectional area is provided with an on-off valve that opens and closes depending on the operating state of the engine. Interposed, low rotation range,
An intake system for an internal combustion engine that can obtain maximum intake efficiency in each high rotation range has been proposed (Japanese Patent Laid-Open No. 58-11
(See Publication No. 9919).

However, in the above-mentioned proposed intake system, the number of intake passages for each cylinder corresponds one-to-one with the number of peaks of intake efficiency that can be obtained.

In order to obtain the maximum intake efficiency in each high rotational speed range, three approximately equivalent intake passages are required, which makes the structure of the intake manifold extremely complicated, and the control of the intake air volume becomes complicated, making it impractical. cause serious difficulties.

(Objective of the Invention) An object of the present invention is to ensure the inertial effect of intake air over a wide engine speed range from low engine speed to high engine speed without needlessly increasing the number of intake passages.

(Structure of the Invention) Therefore, the present invention provides an interposed valve in one of the plurality of intake passages open to the upstream force air, which opens and closes in response to engine load, rotation speed, 1, 0, etc. In the intake system for a zero engine engine, the intake passage downstream of the on-off valve is provided with a volume variable means for changing the volume of the intake passage in accordance with the operating state of the engine.

(Effects of the Invention) According to the present invention, the dimensions of the intake system, particularly the passage volume of the intake passage, can be variably controlled in at least three stages. It is possible to obtain natural frequencies that provide the maximum suction efficiency in each of the three rotation ranges of , intermediate rotation range and high rotation range. Therefore, the inertia effect of the intake air is ensured over a wide rotation range, and smooth and good output performance can be ensured accordingly.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the intake system of engine E shown in FIG. 1, 1 is a primary intake passage that communicates with the combustion chamber 3 of Ennon E through a primary intake boat 2, and 4 similarly communicates with the combustion chamber 3 through a secondary intake port 5. In the secondary intake passage, upstream of these primary and secondary intake passages 1 and 4 is the throttle valve of the common intake passage 6?
Each of them is communicated with a large-capacity surge tank 8 provided downstream.

A fuel injection valve 9 is provided on the downstream side of the primary intake passage 1 to inject and supply necessary fuel toward the 1*intake boat 2.

On the other hand, on the downstream side and upstream side of the secondary intake passage 4, two on-off valves 10 and 11 each consisting of a butterfly valve are provided. Valve shafts 10a, lla of these on-off valves 10.11
One end projects to the outside of the intake manifold 12 that forms the primary and secondary intake passages 1 and 4, and each projecting end has a
Opening/closing levers 13 and 14 are attached and are operated to open when the operating condition of the engine reaches a predetermined condition, respectively, as will be described in detail below.

In addition, 1.5.15 in FIG. 1 is the above-mentioned first order.

Each exhaust boat 16 opens into the combustion chamber 3 so as to face the secondary intake boats 2 and 5, and each exhaust boat 16 is a spark plug installed at the center of the combustion chamber 3.

And these intake and exhaust bows) 2, 5, 15.15 are,
As shown in FIG. 2, by means of intake and exhaust valves 30.31,
Each is driven to open and close at a predetermined timing synchronized with the rotation of the engine E.

Next, the downstream side interposed in the secondary intake passage 4.

Opening/closing control of the two upstream opening/closing valves 10.11 will be explained.

As shown in Figure 2, downstream and upstream on-off valves 10°11
The opening/closing levers 13, 14 are respectively connected to electromagnetic actuators 17, 18 via link ronds, etc., and each actuator 17, 18 receives an opening actuation signal P, , P2 from one drive control circuit. It is now possible to do so.

The drive control circuit 19 receives an output signal proportional to the rotation speed from a rotation speed sensor 20 that detects the rotation speed of the engine E as one input. a second comparator 21°22; The first comparator receives the output of the second comparator 21,22. a second actuator drive circuit 23°24; Either one of the second actuator drive circuits 23 and 24 receives the opening operation signal P.
) or when outputting P2, the downstream on-off valve 1
It is constituted by an OR circuit 25 for opening the actuator 17 of 0.

The positive input side of the first comparator 21 is set to an abnormal value that corresponds to the first rotation speed N1 set as the upper limit of the low rotation range. When the number exceeds the first rotation speed N1, the output becomes High.
H” to “Low”.

On the other hand, on the negative input side of the second comparator 22, a threshold corresponding to the second rotation speed N2, which is set as the rotation speed that separates the intermediate rotation range and the high rotation range, is set, and the threshold value corresponds to the engine rotation speed. “Hi” is reached only when the number of revolutions exceeds the second rotation speed N2.
gh” is output.

As shown in Fig. 3, which shows the opening/closing method of the downstream and upstream opening/closing valves 10.11, in the rotation range lower than the first rotation speed N1, the first
The output of the comparison trout 21 is "High" and the output of the second comparator 22 is "Low". Therefore, the first actuator drive circuit 23 outputs the opening operation signal Pl, and this opening operation signal P1 is applied to the actuator 17 via the OR circuit 251', whereby the downstream opening/closing valve 10 is activated to open. be done. In this low rotation range, the upstream opening/closing valve 11 is kept closed, so the passage volume downstream of the upstream opening/closing valve 11 of the secondary intake passage 4 becomes maximum, and the natural frequency of the intake system decreases. Provides peak suction efficiency in the low rotation range.

Next, when the engine speed reaches an intermediate speed range between the first speed N1 and the second speed N2, the output of the first comparator 21 becomes "Lo-". Second comparator 21.
Both of 22 become “LoIIl” and the opening operation signals p, ,p
Neither of 2 is output.

Therefore, both the upstream opening/closing valve 11 and the downstream opening/closing valve 10 are closed, and the volume between the upstream opening/closing valve 11 and the downstream opening/closing valve 10 becomes a complete dead volume.

In other words, in this case, the effective passage volume of the secondary intake passage 4, which is involved in the inertia effect of the intake air, is reduced by one level compared to the case of the low rotation range, and the natural frequency of the intake system is increased by one level commensurate with the intermediate rotation range. It will be hot.

Furthermore, in a high rotation range where the engine rotation speed rises above the second set rotation speed N2, the output of the second comparator 22 becomes “High”.
h'', the second actuator drive circuit 24 outputs the opening operation signal P2, and the opening operation signal P2 is applied directly to the upstream actuator 18 and via the OR circuit 25 to the downstream actuator 17. As a result, both the upstream and downstream on-off valves 10.11 are opened, and the secondary intake passage 4
supplies intake air from the surge tank 8 to the second intake boat 5.

In this case, the cross-sectional area of the intake system, including the primary and secondary intake passages 1 and 4, increases significantly, so the natural frequency of the intake system increases, and the inertial effect of intake air in the high rotation range increases. You will get it.

As is clear from the above, the on-off valve 10 constitutes the volume variable means according to the present invention.

As a result of the above control, as shown in Figure 4, the suction amount has peaks in three operating ranges: low rotation range, intermediate rotation range, and high 1 rotation range, and increases as the rotation speed increases. do. In other words, it is possible to obtain an intake inertia effect that increases the intake efficiency in each of the low rotation range, intermediate rotation range, and high rotation range.

In the above embodiment, the opening and closing of the on-off valves 10 and 11 was controlled only by the engine speed, but the opening and closing control may be performed by combining the engine load and the engine speed.

Furthermore, in the above embodiment, the primary and secondary intake passages 1.4 are each independently opened into the combustion chamber 3, but a plurality of intake passages may be connected to one intake boat that opens into the combustion chamber. Needless to say, it may be configured as a configuration.

[Brief explanation of the drawing]

FIG. 1 is an explanatory horizontal cross-sectional view of main parts of an engine intake system according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a diagram showing the opening/closing method of the two on-off valves, and FIG. 4 is a graph showing the change in intake amount depending on the engine speed according to the embodiment of the present invention. 1.4... Primary and secondary intake passages, 10.11... Opening/closing valve, 1'L 18... Actuator, 19... Drive control circuit, 20... Rotation speed sensor. Patent applicant Mazda Motor Corporation

Claims (1)

[Claims] (1) In an engine intake system in which a plurality of intake passages whose upstream ends are connected to the atmosphere are opened into a combustion chamber, and at least one of the intake passages is provided with an on-off valve that opens and closes depending on the operating state of the engine, An intake system for an engine, comprising a volume variable means for changing the volume of the intake passage downstream of the opening/closing valve depending on the engine rotational speed l.