JPS60198324A - Intake device for engine - Google Patents

Abstract

PURPOSE:To perform resonance supercharge under wide rotary range of engine by setting such that one of two paths communicating between surge tanks will achieve gas resonance under low and high rotary regions while the other will achieve under intermediate rotary region. CONSTITUTION:Under operation of engine, the outputs from a rotation sensor 14 and a negative pressure sensor 15 are provided to a control circuit 16 which will provide a signal to an actuator 13 thus to open/close a changeover valve 12. Here, said valve 12 is closed under heavy load low rotation region to produce the primary resonance of intake air in a surge tank 1 with primary inherent frequency to be determined by the shape of first communication path 9 thus to perform resonance supercharge to each cylinder with high efficiency. Under heavy load intermediate rotary region, said valve 12 is opened to produce primary resonance of the intake air with primary inherent frequency to be determined by the shape of second communication path 10. While under low load region, said valve 12 is closed continuously to feed the intake air between both chambers 3, 4 of surge tank 1 thus to feed approximately same amount of intake air to each cylinder.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an intake system for an engine.

[Prior art]

Generally, an engine intake device is designed to efficiently supply intake air to the engine. By the way, there have been various methods for supplying intake air to the engine. One example is that the intake air resonates at a natural frequency determined by the shape of the intake passage, causing pressure fluctuations in the intake air. This phenomenon is utilized to efficiently push intake air into the cylinder due to its dynamic effect, thereby improving charging efficiency.

As an intake system for an engine that employs the resonance supercharging method, which uses the resonance effect among the above-mentioned dynamic effects,
Conventionally, as shown in Japanese Unexamined Patent Publication No. 56-115818, a surge tank is provided for each cylinder group in which the ignition order is not consecutive, and a first tank is provided for communicating between the surge tanks.
A second communication path is provided, and the first communication path is provided. The passage length and cross-sectional area of the second communication passage are set so that resonance of the intake air is obtained in the ranges below the set rotation speed and above the set rotation speed, respectively, and the switching valve provided in the second communication passage is set so that the engine speed increases. There was one that opened and closed depending on whether the engine was below or above a set value to perform resonance supercharging over a wide engine speed range.

However, the device described in the above-mentioned conventional publication has a problem in that sufficient resonant supercharging is not performed in an operating range where the engine speed is high, and the engine output is not sufficiently improved.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide an intake system for an engine that can perform resonance supercharging over a wider rotation range.

[Structure of the invention]

The inventor of the present invention has made the following findings as a result of intensive research aimed at realizing resonant supercharging in a wider rotation range. In other words, in Figure 1, the passage length and cross-sectional area of the communication passage between the surge tanks are set so that intake resonance can be obtained in the low engine speed range, and within the normal engine speed range. The graph shows the results of measuring changes in the amplitude of intake pressure fluctuations while changing the engine speed. According to Fig. 1, the amplitude of the pressure fluctuation increases as the engine speed increases, and the amplitude reaches a maximum at the set speed r, and as the speed increases further, the amplitude of the pressure fluctuation gradually decreases. . Conventional devices utilize this phenomenon to perform resonance supercharging.

Then, as the rotation speed increases further, the amplitude value of pressure fluctuation does not simply decrease, but at a rotation speed of 2 times the set rotation speed.
It reaches its maximum at r.

This is a phenomenon that occurs due to the secondary resonance of the intake air, and if this phenomenon is effectively utilized, it is possible to achieve resonant supercharging at high engine speeds without complicating the structure. Conceivable.

Therefore, the present invention proposes that if the shape of the communication passage is set so that the primary resonance of the intake air can be obtained in the low rotational speed range of the engine, the amplitude of the pressure fluctuation can be reduced due to the secondary resonance of the intake air within the engine's normal operating rotational range. Focusing on the fact that there is a maximum rotational speed, we developed the first system that connects the surge tank. In the above-mentioned engine intake system that includes a second communication passage and a switching valve and performs resonance supercharging, the first communication passage is set so as to obtain gas resonance in a low and high rotation range, Second
The communication passage is set to obtain gas resonance in the medium speed range, and the switching valve is closed in the low and high speed range and opened in the medium speed range. This allows resonance supercharging to be performed not only in the rotation range but also in the high rotation range.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

2 to 5 show an engine intake system according to an embodiment of the present invention. In the figure, 1 is a surge tank,
The surge tank 1 is divided into a first chamber 3 and a second chamber 4 by a partition wall 2.
It is defined as. On the bottom of the first chamber 3, there are 1st, 3rd, and 3rd cylinders with discontinuous ignition order. The upstream ends of intake manifolds 5a, 5b, and 5c extending to each of the fifth cylinders are connected to the bottom of the second chamber 4, and the second, fourth, and fourth cylinders, which also have non-consecutive ignition orders, are connected to the upstream ends of intake manifolds 5a, 5b, and 5c extending to each of the fifth cylinders. Intake manifolds 5d, 5 extending to each sixth cylinder
The upstream ends of e and 5f are connected. Here, the engine is the first. Second. Third. 4th. Fifth. It is assumed that the 6th cylinder is ignited at every 120° crank angle in the ignition order.

Further, a downstream end of an intake pipe 6 is connected to a side surface of the surge tank 1. The downstream end of the intake pipe 6 is formed with two intake passages 7, 8, which are connected to the first chamber 3 and the second chamber 4 of the surge tank 1, respectively.
Both intake passages 7 and 8 are connected to the first chamber 3 and the second chamber of the surge tank 1.
A first communication path 9 communicates with the chamber 4. This first
The passage length Ll and passage cross-sectional area S1 of the communication passage 9 are set in a low engine rotation range of 2700 rpm or less, and 5200 rpm.
The length and cross-sectional area are set such that gas resonance can be obtained in a high rotation range of pm or higher. In addition, both the intake passages 7
, 8 are respectively provided with throttle valves 11a and 11b.

Further, an opening 10 is formed in the partition wall 2, and the opening 10 serves as a second communication passage that communicates the first chamber 3 and the second chamber 4 of the surge tank 1 in parallel with the first communication passage 9. , the second
The passage length of the communication passage (the thickness of the partition wall 2) L2 and the passage cross-sectional area (the area of the opening 10) S2 are determined when the engine rotation speed is 270 Or
The length and cross-sectional area are set so that gas resonance can be obtained in a medium rotation range of pm or more and 5200 rpm or less. Further, this opening 10 is provided with a switching valve 12 for opening and closing it, and the switching valve 12 is opened and closed by an actuator 13.

In the figure, 14 is a rotational speed sensor that detects the engine rotational speed, 15 is a negative pressure sensor that detects the intake negative pressure downstream of the throttle, and 16 is a switching valve control using the engine rotational speed and intake negative pressure as parameters. 14.
This is a control circuit that receives the output of the actuator 15, reads an open signal or a close signal, and applies it to the actuator 13. Here, as shown in Fig. 5, the switching valve control knob stores an open signal regardless of the engine speed at low load when the intake negative pressure is less than the set value -100 mm 1 g, and the intake negative pressure When the load is higher than the set value -100mmHg, the engine speed is in the low rotation range of 270Orpm or less, and 52
A close signal is stored in a high rotation range of 00 rpm or more, and an open signal is stored in a medium rotation range of engine rotation speed of 2700 rpm or more and 520 rpm or less.

Next, the operation will be explained.

When the engine starts operating, the re-outputs of the rotation speed sensor 14 and the negative pressure sensor 15 are applied to the control circuit 16.
Then, an open signal or a close signal is read out from the switching control map (see Fig. 5) depending on the load state and rotational state of the engine, and this signal is applied to the actuator 13 to control the switching valve 12.
is opened and closed.

Then, in the high load and low speed range of the engine, the switching valve 1
2 is closed, and the intake air in the surge tank 1 resonates first at a first natural frequency determined by the shape of the first communicating passage 9, etc., and each cylinder is efficiently resonantly supercharged. In addition, in the high-load and medium-speed range of the engine, the switching valve 12 opens, and the intake air in the surge tank 1 resonates first at the first natural frequency determined by the shape of the second communication passage 10. Resonant supercharging will be performed efficiently in each cylinder.

In the high-load, high-speed range of the engine, the switching valve 12 closes as in the case of the low-speed range, but in this case, the intake air has a secondary natural frequency determined by the shape of the first communication passage 9, etc. Since the next resonance occurs, resonance supercharging is efficiently performed in each cylinder in this case as well.

On the other hand, in the low engine load range, the switching valve 12 is always kept open, so the first chamber 3 of the surge tank 1
Intake air is supplied between the and second chamber 4 through the second communication passage 10, and the pressure in the first chamber 3 and the pressure in the second chamber 4 are approximately equal, so each cylinder has approximately the same pressure. The device of this embodiment as described above utilizes the secondary resonance of the intake air to perform resonant supercharging in the engine high speed range, so it is different from the conventional device. In comparison, resonance supercharging can be realized in a wider rotation range without complicating the structure in any way, and as a result, the engine output, particularly in the high rotation range, can be improved as shown by the solid line a in FIG. In FIG. 6, the dashed dotted line C and the dashed line indicate the 1st line, respectively. Second communication path 9
This figure shows the change in engine output obtained when using the resonance of the intake air determined by 10 degrees.

In addition, if resonance supercharging is performed at low loads in the low and high engine speed ranges in the same way as at high loads, since the engine output is not so large at low loads, it is necessary to obtain intake resonance. The engine pumping loss that occurs during this period is large compared to the engine output, resulting in a noticeable drop in engine output. In addition, since the amount of intake air is small in the low load range of the engine, if there is variation in the distribution of intake air to the first chamber 3 and second chamber 4 of the surge tank l due to the shape of the intake pipe 6, etc. Cylinder group communicating with chamber 1 and 2nd chamber
Due to the difference in output between the cylinders communicating with the chamber 4, engine torque fluctuations become noticeable, and unpleasant engine vibrations may increase. In contrast, in this device, the switching valve 12 is opened during low load in the low engine speed range and high engine speed range, so that resonance supercharging is hardly performed.
The engine output does not decrease significantly due to the pumping loss, and the first chamber 3 and the second chamber 4 are connected to each other through the second communication passage.
Since the intake air amount is corrected between the two, even if variations in intake air distribution occur in the intake passage, unpleasant engine vibrations will not increase. Furthermore, when the engine is under low load in the mid-speed range of the engine, it is preferable to close the switching valve 12 to reduce pumping loss caused by the resonance effect, but at low load when the amount of intake air is small, the above-mentioned variation in intake air distribution is more important. It is preferable to take countermeasures from the viewpoint of engine stability, and in this device, the switching valve I2 is kept open.

Note that in the above embodiment, the inside of the surge tank is separated from the first
Although the surge tank is divided into a chamber and a second chamber, the surge tank may of course be formed separately in the present invention. Further, the number of surge tanks may be more than two. Furthermore, instead of providing two throttle valves in the first communication passage, one throttle valve may be provided in the intake passage upstream of the first communication passage.

〔Effect of the invention〕

As described above, according to the present invention, the first casing that communicates with the surge tank. In an engine intake system that includes a second communication passage and a switching valve and performs resonance supercharging, the first communication passage is set to obtain gas resonance in the low and high rotation ranges, and the first communication passage is The two-way passage is set so that gas resonance can be obtained in the medium speed range, and the switching valve is closed in the low and high speed ranges and opened in the medium speed range, so that low engine speeds can be achieved.

This has the effect of efficiently performing resonance supercharging not only in the medium rotation range but also in the high rotation range.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram for explaining the present invention, and FIGS. 2 and 3 are a cross-sectional plan view and a cross-sectional side view of an engine intake system according to an embodiment of the present invention, respectively. FIG. 4 is a circuit configuration diagram of the above device, FIG. 5 is a diagram showing open/close signals of the control circuit 16 in the above device, and FIG. 6 is a diagram for explaining the effects of the above embodiment. 3.4...1st chamber, 2nd chamber (surge tank), 9...
・First communication path, 10... opening (second communication path), I2・
...Switching valve, 16...control circuit. Patent Applicant: Toyo Kogyo Co., Ltd. Agent, Patent Attorney Ken Hayase - Figure 1 Enshi Shiro Chui! 1 (rpm) -111 Figure 2 Figure 4 Figure 5 Number of times (rpm) → Figure 6, 1Ty1. ;') Rotating wheel Mke□

Claims (1)

[Claims] (1) A plurality of surge tanks, each of which communicates with each cylinder in which the firing order is not consecutive, and whose passage length and passage cross-sectional area are designed so that gas resonance can be obtained in a predetermined low rotation range and high rotation range. A first communicating passage is set and communicates between the surge tanks, and the passage length and cross-sectional area are set so as to obtain gas resonance in a predetermined medium rotation range, and the first communicating passage is parallel to the first communicating passage. a second communication path that communicates between the surge tanks;
An intake system for an engine, comprising: a switching valve that opens and closes the second communication passage; and a control circuit that closes the switching valve in a predetermined low rotation range and high rotation range and opens the switching valve in a predetermined middle rotation range.