JPS5867958A - Intake device of engine - Google Patents

Abstract

PURPOSE:To always maintain output power of an engine to a maximum level in accordance with its operational condition, by changing length of an air introducing pipe in accordance with a revolving speed and improving intake efficiency with simple constitution. CONSTITUTION:An air introducing pipe 10 in the upstream side of a throttle valve (not shown in the drawing) is constituted in a pipe length-changeable state correspondingly inverse proportion to an engine revolving speed, in such a manner that a pipe length is decreased in a high engine speed operational range while increased in a low engine speed operational range through branch pipes 11-13. In the low speed range, air is introduced through the first branch pipe 11 of passage in the largest length to hold volumetric efficiency to a high condition. Then from under this condition, if the revolving speed is further increased, a check switch 28 is opened to actuate a damper 16 in such a manner as to switch the air introducing line to the second branch pipe 12. Accordingly, decrease of volumetric efficiency in accordance with cylinder vibration in the vicinity of a throttle valve full opening position is prevented by decrease of a length of the air introducing line, further the length is set in such a manner as to obtain maximum volumetric efficiency, and output power can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for an engine, and more particularly to an intake system that is favorable or unfavorable to engine output.

FIG. 1 shows a conventional engine intake system using an electronic fuel injection system. As shown in this figure, in the conventional intake system, air is introduced into an air introduction pipe 2 from an air cleaner, and is introduced into an intake pipe 4 while controlling the amount of air with a throttle valve 3. In the intake pipe 4, fuel is injected from the fuel injection valve 5 to form an air-fuel mixture, which is then supplied to the engine 6. In this case, the air introduction pipe 2 has a certain size that can supply sufficient air mainly depending on the cylinder volume, and has a certain shape depending on the size of the engine room.

By the way, in order to improve the output of the engine, it is important to increase the intake efficiency. For this reason, normally, as shown in Figure 2, the exhaust valve and the intake valve are set so that their two swords are opened across the top dead center, and the force of the inflow of intake air is used to The residual flame exhaust gas is actively returned.

However, the pressure in the air introduction pipe 2 on the upstream side of the valve near the fully open throttle box 3 of the intake system fluctuates due to air column vibration, as shown in Figure 3, and in the negative pressure region (shaded area). Because the pressure gradient is reversed, air flows backwards from the engine side, causing a problem that reduces suction efficiency. This phenomenon tends to occur when the pulp overlaps as shown in FIG. 2, and therefore air intake is inhibited by the presence of a negative pressure region, resulting in a decrease in output.

For this reason, in recent years, turbochargers have been adopted to systematically supply air, but adding new equipment requires VC, complicating the structure, and increasing the weight of the 2Jl ] and other disadvantages are significant.

The present invention focuses on the above-mentioned conventional problems, and uses a simple configuration to improve intake efficiency and always maintain maximum engine output according to operating conditions without the need for a device such as a turbocharger. The purpose of the present invention is to provide an improved engine intake system that allows the engine to perform the following functions.

The present invention aims at eliminating the negative pressure region where the pressure on the air introduction pipe side is lower than the pressure on the cylinder side in pressure fluctuations due to air column vibration of the introduced air. This is based on the idea that it improves efficiency, which in turn leads to an increase in output. By constantly changing the pipe length, the engine speed N (
This is based on the results of determining the volumetric efficiency (%) r of the air sucked into the cylinder with respect to r, p, m) (Section 4.A). As can be understood from this 5g4 diagram, when the air introduction pipe support L = 100rraQ, it has a maximum of 111A in the region where the engine speed is high, and if the length L is gradually increased inversely proportionally (L = 50On + m, L = 800mm) ),this,
Points B and C show a tendency to shift toward lower rotational speeds.

Therefore, if the length of the air introduction pipe can be changed in inverse proportion to the rotational speed, the volumetric efficiency can always be maintained at a constant value at any rotational speed. This is the fifth
In the figure, the length of the air introduction pipe L = 200 rrs, L =
500, Ensif 4+ll output when running,
This is understandable from the comparison shown with the engine shaft output when changing the air intake pipe holder to correspond to the envelope curve where the volumetric efficiency is always extremely thick.

For this reason, the engine intake system according to the present invention is designed to have a length that is adequate in the operating range where air is introduced upstream of the throttle valve and where the engine speed is high, and when the engine speed is low. In the JA transfer area, make the length short,
It is designed so that the pipe length can be changed in inverse proportion to the rotational speed. With this configuration, the volumetric efficiency in the cylinder is maximized to maintain maximum output.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 6 shows a sectional view of essential parts of an engine intake system according to the first embodiment of the present invention. As shown in this figure, the air intake device includes an air intake pipe 10 that guides air to an air cleaner 171 and a valve, and three branch pipes 11, 12, and 10 of different lengths.
13, and the sky λt will eventually become the sword's branching tube 11~
13 is formed to flow therethrough. That is, the air introduction pipe 10 is connected to the first valve at the proximal end 14 when the throttle valve is open.
It is branched into a branch pipe 11 and the shortest 5g3 branch pipe 13, and both of these branch pipes 11 and 13 are each connected to the air cleaner 1 once. In addition, the culvert 1 branch officer 11 is located at the 2nd branch on the way.
The branch pipe 12 is branched, and the second branch pipe 12 is also formed to open into the air cleaner l. These 41.
The branch part of the third branch pipe 11.13, and the branch part of the first branch pipe 11.13. Second branch pipe 1
Switching dampers 15 and 1 are installed at the branch portions 1 and 12, respectively.
6 is provided. These dampers 15 and 16 are 5. Second
Branch pipe 12 Air from the Aculina 1 is introduced only through the first branch pipe 11, and by switching one damper 16, the air is introduced into the second branch 1it.
12a-A, and the third branch pipe 13 by the other damper 15.
The inflow path is switched so that the inflow passage passes through the inlet.

The length of the air relief introduction path formed by these first to third branch pipes 11 to 13, that is, the length from the air cleaner 1 to the throttle valve, is selected in a discrete manner of 1 m to 1 m. This length depends on the engine displacement, the amount of pulp overlap, the shape of the intake bone, etc., but may be set to a length l such that the volumetric efficiency is maximized in each bright transition region. On the actual flow side, the length of the introduction path of the first branch pipe 11 is set to 80
0 Cabinet, 2nd. 400g of that of the third branch pipe 2.13,
Excursion to 100mm. Then, in the low rotation range of the engine, the first branch pipe 11 is connected, and in the middle rotation range, the second branch pipe 1 is connected.
2 is switched by dampers 15 and 16 so that air is introduced through the second branch pipe 12 in the high rotation range, thereby covering the entire operating range.

By the way, air introduction i! Shikotani damper 15, 16 to make 1m switching, 1 l'L zono% diamond flannel,
Devices 17 and 18 are connected and operated. These tire ram devices 17, 18 have rods 19, 20 for actuating dampers 15, 16 that are diaphragms, 21, 22
The diaphragm 21°22 is attached to the spring 2
3.24 and is driven by the acting force in the shell pressure chamber 25.26. Also, these diaphragm mounting ml 7゜18 has a check switch 27.2.
8, the connecting pipes 29 and 30 are negative pressure chambers, 25.2
6 + lil n% connecting pipe 29.30 is air introduction R1
Open in the venturi section (not shown) of 0. +ijJ
If the check switch 27.28) is set to 174
Figure 7 shows one check switch 27.It detects that the check switches 27, r, f, and ir are complete (case 31).
A suction valve 32 that can be evacuated through the passageway is disposed inside the pulp valve 32, and a spring 33k device is used to fully open the pulp 32 by direct pressure suction force. Two check switches 27
．． 28, the spring constant of the spring 33 is different and 9
Negative pressure ff: is introduced into the valley diaphragm device 17 and 18 so that a branch passage corresponding to the rotational range of the engine is selected.

In the engine intake system according to the first central air intake system configured in this way, the passage length is the longest in the low rotation range, and the
Air is introduced through the T-branch pipe 11 and is kept in a vacuum chamber with high volumetric efficiency. Due to this bad condition, if the rotation speed is increased by M with the masu fully open, the air introduction path will be connected to the second branch pipe 1.
2, the check switch 28 is opened and the damper i6v is operated. Therefore, the drop in volumetric efficiency caused by the low A of the air column near the fully opened throttle valve is prevented by the short ratio of the air introduction path length, and the volumetric efficiency is set to maximize the volumetric efficiency. , so the output is the same as above. When the rotational speed starts to increase, the damper 15 is activated, and the length of the air introduction path becomes the shortest, thereby increasing the output direction at high rotational speeds.

As described above, according to this embodiment, the length of the air flow pipe 10 changes depending on the total rotation of the throttle valve. It is possible to prevent the decrease in main volume efficiency near the opening, and always maintain and protect the high KJJ output in the first rotation area.

Moreover, simply taking the length of the air introduction u10, lIt d
), all you have to do is change it, and you just need to use the suction pressure as the operating source, so you can achieve an output increase with an extremely simple configuration, and you can safely replace complicated devices such as turbochargers. do not.

In addition, in the above implementation, check switch 27.
The output end of 28 is the throttle valve open, drum, rotation, exhaust to 1M degree,
Appropriate measures can be taken, such as combustion chamber pressure and intake manifold pressure downstream of the fall valve. Furthermore, the length of the branching and ultraviolet rays differs depending on the length of the V-engine, and it is preferable to select a length that provides the maximum efficiency that has been experimentally confirmed.

FIG. 8 shows another modification of the operation of the diaphragm device 17 (18), in which the throttle valve 3 is fully opened and a negative pressure is applied to the positive pressure value 25 of the diaphragm device 17. That is, the negative pressure introduction path 34 uses the venturi section 35 upstream of the scale valve 3 as a pressure source, and is communicated with the negative pressure 25 of the diaphragm device 17 via the check switch 27A'. The check switch 27A has a solenoid structure, and is configured with a plunger 36, a coil 37, and a spring 38 to open and close the passage. The coil 37 is energized from the battery 39 by operating a switch 42 by a full-open detection rod 41 that detects when the throttle valve 3 is fully opened by the accelerator pedal 40 . Further, the switch 42 has a gamma-land switch structure, and is opened by inputting the engine 11 rotation speed, which is the timing for switching the introduction path, and by detecting that the throttle valve is fully open. Therefore, depending on the number of revolutions, a limited number of check switches can be activated.
The necessary -tM switching is performed by the selected switch.

In this way, by establishing a method for detecting fully open throttle valve and negative pressure for diaphragm/operation, 1. ! An appropriate branch pipe length introduction Q can be selected depending on the quadruple rotation state, and maximum output can always be maintained.

FIG. 9 shows a second embodiment in which the length of the air introduction pipe can be changed. The air introduction pipe 10A according to this embodiment has a main introduction pipe 43 provided with one nozzle pipe 44, and an upstream branch opening with a nozzle 15 disposed.Other configurations are as follows. , fi6.8 is the same 1* as in Figure 5, so the explanation will be omitted.The length of the bypass pipe 44 is set to the optimum length in advance based on the experimental results shown in Figure 5g4. , it is sufficient to set the receptacle to approximately 1.5 to 3 times the pipe length of the main introduction pipe 43.

In this embodiment, since the damper 15 is disposed at the upstream branch opening, the mesh of the volume of the main pipe 43 and . The imaginary state where the partial pressure becomes negative pressure is reduced.

This has been confirmed through experiments.

FIG. 10 shows a third embodiment in which the length of the air introduction tube is changed. In the air introduction pipe 10B according to this embodiment, a double rib outer pipe 45 is fixedly attached to the air cleaner 1, and an inner pipe 46'ff is rotatable. The outer pipe 45 has a third branch pipe 13B% and a second branch pipe W1 from the upstream side along the pipe axis direction.
2B and the first limb anterior 1B are arranged and communicated. The inner pipe 46 is formed hollow to allow air to flow from the air cleaner 1, and a valley branch pipe 118 is provided on the wall of the inner pipe 46.
Communication through holes 47, 48, and 49 corresponding to 13B are formed at different positions in the circumferential direction. The inner pipe 46 is the motor 5
0 allows rotation.

Therefore, the length of the pipe can be changed by selectively changing the rotational position of the inner pipe 46 according to the engine speed.

This embodiment has the advantage that the length of the air introduction pipe can be easily changed by controlling the motor 50 alone.

Further, FIG. 11 shows a fourth implementation row in which the length of the air introduction pipe is changed depending on the operating conditions. The air introduction pipe 10C according to this embodiment differs from the previous embodiment in that the air introduction tube 10C is different from the previous embodiment.
The length was changed by expanding and contracting C itself. That is, the air introduction pipe 100 has a bellows structure, and the air cleaner 1 is moved in the axial direction of the pipe along a guide rail 51, and is driven by a metal motor 52.

In such an embodiment, since the pipe length can be changed continuously,
Continuous control is possible to achieve maximum output at any rotation speed, making it possible to obtain maximum volumetric efficiency.

Further, FIG. 12 shows a fifth embodiment. The air introduction tube IOD in this embodiment is provided with a bright line partition plate 53 inside, and the length of the introduction path is increased while the introduction tube 10D itself is shortened.

13D is provided.

Such an implementation has the advantage that the length of the introduction path can be changed over a wide range while the introduction pipe 10D has a short structure.

As explained above, according to the engine intake system according to the present invention, there is no decrease in output due to a decrease in volumetric efficiency near the fully open position of the throttle valve, and the engine air intake system is effective over the entire engine speed range from low to high engine speeds. The amount of air sucked in is always maximized, and the
It is possible to increase the output by 1% on average in the 2000CC class by 5% on average.

[Brief explanation of the drawing]

Figure 1 is a front view showing the intake system of a conventional engine, Figure 2 is a diagram of pulp operation, Figure 3 is a diagram of pressure changes in the air introduction pipe, Figure 4 is a characteristic diagram of volumetric efficiency versus engine speed, Fig. 5 is a diagram showing the relationship between air introduction pipe length and shaft output, Fig. 6 is a sectional view of the main parts of the intake system according to the first embodiment, Fig. 7 is a sectional view of the check switch, and Fig. 8 is the operation of the diaphragm device. A schematic configuration diagram of a modified example of the device, FIG. 9 is a sectional view of the main part of the intake device according to the second embodiment, FIG. 1O is a sectional view of the same main part of the third embodiment, and FIG. Cross-sectional view of the same main part, 1st
FIG. 2 is an lfr side view of the same essential part of the fifth embodiment. l...Air cleaner, 3...Storage valve, 10. IOA
~10D...Air inlet pipe, 11-13...Branch pipe,
17°18...Diaphragm device. US exchange, 1 Takegami Ebisu, I pressure support 1 engine rotation speed N Fig. 9

Claims (1)

[Scope of Claims] 1. In an intake system that supplies air taken from an air cleaner to an engine through a throttle valve, an air introduction section g on the upstream side of the throttle valve corresponds inversely to the engine/rotation speed. Introduction - An intake system for an engine characterized by being formed to be able to change. 2. The air introduction pipe section is formed from a plurality of branch front sections having different lengths, and the air passage can be switched by a switching means such as a damper. Engine intake system. 3. The engine air intake device according to claim 1, wherein the air introduction pipe portion is formed to be freely compressible and its length can be changed.