JP2750122B2 - Engine intake system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine in which intake efficiency is improved by a resonance effect.

[Conventional technology]

2. Description of the Related Art Conventionally, various intake devices for an engine in which charging efficiency is increased by a dynamic effect of intake air have been known. For example, in an apparatus disclosed in Japanese Patent Publication No. 60-14169, in a multi-cylinder engine, two intake passages respectively connected to two groups of cylinders in which cylinders whose intake order is not continuous are set to be the same group are provided. Each of the intake passages is provided with an enlarged chamber (a large volume collecting chamber) to which the upstream end of the intake manifold branch is connected, and a resonance passage extending upstream from the enlarged chamber. A switching device is provided for disconnecting the intake passages from each other, and an upstream end of each intake passage is connected to an upstream collecting chamber. According to this device, when the switching device is in a state where the intake passages are shut off from each other, the intake pressure wave that is inverted and reflected in the upstream collecting chamber causes excessive inertia in a region where the engine speed is relatively low. When the supply effect is obtained and the switching device communicates with each of the intake passages, the reverse reflection position of the pressure wave is brought closer to the intake port, so that inertia over a region where the engine speed is relatively high is obtained. The salary effect is obtained.

[Problems to be solved by the invention]

However, according to the above-mentioned intake device, since a large-volume expansion chamber is provided in a portion where the intake manifold branch portions are gathered, the intake system becomes large, and a large installation space is required when the intake system is mounted on an automobile. There are inconveniences.

Incidentally, in the case of the V-type engine, for example,
As seen in Japanese Patent Publication No. 5 (1993), an intake manifold having curved individual intake passages corresponding to branch portions and a space corresponding to an enlarged chamber communicating with the individual intake passages is arranged in a space between both banks. In some cases, the overall size is reduced while providing an inertial supercharging effect. However, even with this structure, since the intake manifold disposed between the two banks is provided with an enlarged chamber that communicates with the branch portion, it is unavoidable that the intake manifold projects considerably above the upper end of the bank. The overall height becomes large, and it is difficult to keep the bonnet height low when mounted on an automobile.

That is, in the structure in which the intake manifold branch section is connected to the expansion chamber as in these conventional devices, there is a limit in the degree of freedom of the layout of the intake system with respect to the engine and the compactness (in particular, the reduction in height). For this reason, the expansion chamber is abolished. For example, two pipe-shaped intake passages having no expansion chamber are connected to the respective intake ports of the two cylinder groups in which cylinders in which the intake order is not continuous are grouped into short branches. It is conceivable that the two intake passages are connected via a pipe, and the two intake passages are gathered at an appropriate position on the upstream side so that the pressure wave is reflected back at this portion. However, in this case, a difference occurs in the length of the pressure wave propagation path between the intake port and the pressure wave reversing reflector for each cylinder, and if the above-described intake passage is shortened in expectation of a supercharging effect particularly in a high-speed region, Since the above-mentioned difference becomes relatively large and the action of the pressure wave on each cylinder becomes unbalanced, it becomes difficult to exert a sufficient supercharging effect on each cylinder.

In view of the above-described circumstances, the present invention uses the annular passage for resonance to provide a structure advantageous to the layout and compactness of the intake system, and particularly to achieve a dynamic effect without causing imbalance for each cylinder, particularly in a high-speed range. It is an object of the present invention to provide an intake device for an engine that can effectively increase the charging efficiency by affecting each cylinder and have a dynamic effect in a high speed range and a low speed range.

[Means for solving the problem]

The intake device of the present invention has an annular shape in an intake passage communicating with an intake port of each cylinder so as to circulate a pressure wave propagating from each intake port, and a predetermined state in which a resonance state of the pressure wave is obtained in a high speed region. A resonance annular passage having a passage length is provided, and the engine speed and the natural frequency of the intake passage are tuned in a high-speed region and a low-speed region, respectively. In order to obtain the dynamic effect of the intake air in which the directional amplitude increases, the pressure wave propagates through the resonance annular passage in the high speed region, while the pressure wave propagates in a different path from the resonance annular passage in the low speed region. Switching means for switching the pressure wave propagation path so that the path shape and dimensions of the another path are set so that a resonance state of the pressure wave is obtained in a low speed region and a dynamic effect of intake air is generated. What is characteristic That.

[Action]

According to the above configuration, in the high-speed range, the resonance effect is obtained between the cylinders by the pressure wave propagating through the resonance annular passage, and the pressure propagation path is switched by the switching means, so that in the low-speed range. In another path, a dynamic effect due to the pressure wave is obtained.

〔Example〕

FIG. 1 shows an embodiment in which the apparatus of the present invention is applied to a three-cylinder engine. In this figure, the engine body 1 has first, second, and third cylinders 2a, 2b, 2c. The cylinders 2a to 2c are provided with intake ports 3a to 3c and exhaust ports 4a to 4c, respectively. These intake ports
The intake ports 3a to 3c and the exhaust ports 4a to 4c are opened and closed at predetermined timings by intake valves and exhaust valves (not shown).

In the intake passage communicating with each of the intake ports 3a to 3c, there is provided a resonance annular passage 5 having no expansion chamber between each of the intake ports 3a to 3c. The resonance annular passage 5 is formed in an annular shape so as to circulate the pressure wave propagating from each intake port, and has a predetermined passage length at which a resonance state of the pressure wave as described in detail later is obtained in a high speed region. Is formed. Each of the intake ports 3a to 3c is connected to the resonance annular passage 5 via short independent intake passages 6a to 6c.
The intake passage 7 is connected to the resonance annular passage 5 at an appropriate position such as a side portion of a portion to which the intake port is connected. Each of the independent intake passages 6a to 6c is formed to have a sufficiently short length, so that the inertial tuning rotational speed by the independent intake passages 6a to 6c is set to the maximum allowable rotational speed of the engine (engine It is set to be higher than the maximum number of rotations permitted from the viewpoint of reliability and the like.

The resonance annular passage 5 is provided with an on-off valve 8 as switching means for switching the pressure wave propagation path. The on-off valve 8 is opened and closed according to the engine speed by a control circuit and an actuator (not shown) so as to block the resonance annular passage 5 in a low speed range and to associate the resonance annular passage 5 in a high speed range. . An air flow meter 9 for detecting the amount of intake air, a throttle valve 10 for adjusting the amount of intake air in accordance with an accelerator operation, and the like are disposed in the intake passage 7. An upstream end of the intake passage 7 is provided with an air cleaner 11. It is connected to the. A volume section 12 may be provided in the intake passage 7 as shown by a two-dot chain line.

In the present embodiment, in the low-speed range, the on-off valve 8 blocks the resonance annular passage 5 so that the pressure wave propagates through the intake introduction passage 7 which is another path. The dimensions, such as the shape and the length, of the pressure wave propagation path formed by the intake introduction passage 7 are set so that a resonance state of the pressure wave is obtained in a low-speed region, and a dynamic effect of the intake occurs.

According to the apparatus of this embodiment, the engine speed and the natural frequency of the intake passage are respectively defined by the resonance annular passage 5 in the high speed region and by the pressure wave propagation path constituted by the intake passage 7 in the low speed region. And a dynamic effect of intake such that the positive amplitude of the intake passage pressure immediately before the intake valve becomes large at substantially the intake valve closing time is obtained. The specific operation will be described with reference to FIG. 1 and FIG.

In the vicinity of the intake ports 3a to 3c of the cylinders 2a to 2c, there is a basic pressure oscillation (line A in FIG. 2) in which the operation of each cylinder causes a negative pressure during the intake stroke and a positive pressure at the end of the intake stroke. )
Occurs. In the low-speed range where the on-off valve 8 is closed, the pressure wave is propagated to the intake passage 7 as shown by a broken line arrow in FIG. At 12, the negative pressure and the positive pressure are inverted and reflected, and the pressure wave reciprocates between the intake port and the upstream opening end or the volume 12. In this case, when the positive pressure wave generated by reversing the negative pressure generated in the middle of the intake stroke acts on the intake port of the own cylinder at the end of the intake stroke (two-dot chain line arrow in FIG. 2), An inertial supercharging effect is obtained.
Therefore, in order to obtain such a supercharging effect in a low speed range, the intake port and the upstream open end or the volume
The length of the passage between 12 and may be set.

On the other hand, in a high-speed region where the on-off valve 8 is opened, a pressure wave generated near the intake port is indicated by a solid line arrow in FIG.
As shown in the example of pressure propagation from the cylinder 2a), the pressure is divided into two directions, the upstream side and the downstream side, and propagates so as to go around the resonance annular passage 5, respectively. Act on the intake port of the cylinder. In this case, since there is no pressure inverting portion in the pressure propagation path by the resonance annular passage 5, the pressure wave propagated without inversion acts on the intake port.

Then, when the time when the pressure wave substantially makes a round in the annular passage for resonance 5 coincides with the cycle τ of the basic pressure oscillation, that is, the length L of the entire annular passage for resonance 6
When the relationship between (equivalent pipe length taking into account the influence of the volume of the independent intake passage, etc.) and the above-mentioned period τ is τ = L / a a: sound velocity, as shown by a solid arrow in FIG. The pressure wave generated in the second cylinder 2a and transmitted through the resonance annular passage 6 overlaps the pressure wave generated in the second cylinder 2b, and similarly, the second cylinder 2b
The pressure wave propagated from the third cylinder 2c overlaps with the pressure wave generated in the third cylinder 2c, and the pressure wave propagated from the third cylinder 2c overlaps with the pressure wave generated in the first cylinder 2a. In this way, due to the resonance effect in which the pressure wave resonates between the cylinders, the pressure oscillation is strengthened as shown by the line B in FIG. 2, and the charging efficiency of each cylinder is increased.

In particular, if a pressure wave is propagated through the resonance annular passage 5 so as to have a supercharging effect in a high-speed region, the resonance annular passage is not provided, and the intake port and the independent intake passage are arranged at a higher speed. As compared with the case where the supercharging effect is provided by the inertial effect due to the reciprocating propagation of the pressure wave between the pressure reversing portion such as the volume portion provided in the upstream intake passage, the pressure wave acting on each cylinder is amplified. The balance is reduced, and dynamic effects in the high-speed range are effectively exhibited.

In other words, when an inertial supercharging effect is to be exerted by a pressure wave reciprocatingly propagating in the path between the intake port and the pressure reversing section, one half of the period τ of the basic pressure oscillation shown in FIG.
Since the pressure wave needs to reciprocate along the path at a time corresponding to the following equation, the relationship between the cycle τ of the pressure oscillation and the length L ′ (equivalent pipe length) of the passage from the intake port to the pressure inversion section is τ / 2 = 2L '/ a ... Since the cycle τ of the pressure oscillation becomes shorter as the engine speed becomes higher, the supercharging effect in the high-speed region is required to be longer than that in the low-speed region. Needs to be set short. However, when an inertia effect is provided by a passage extending from the independent intake passage to the pressure reversal portion of the upstream intake passage, the length of the passage from the intake port of each cylinder to the pressure reversal portion includes the mutual intake of the cylinders. There is a difference corresponding to the length between the ports, and the shorter the passage length L 'is, the larger the difference becomes, and the unbalance of the pressure waves acting on each cylinder becomes large. It is difficult to increase the filling efficiency.

On the other hand, according to the apparatus of the present embodiment, a resonance effect is obtained when the above equation is satisfied. Comparing this equation with the equation, if the period τ of the pressure oscillation is the same, the resonance annular passage 6 The total equivalent pipe length L is four times the equivalent pipe length L 'in the case of the above equation, and even in a high-speed region, since the pressure wave propagation path for each cylinder is relatively small, the imbalance of pressure waves acting on each cylinder is relatively small. Becomes smaller. Therefore, even in a high-speed range, the pressure wave is applied almost uniformly to each cylinder, and the charging efficiency of each cylinder can be effectively increased. FIG. 2 shows a basic resonance state in which one pressure wave of pressure oscillation generated in the same cylinder group propagates so as to overlap with the next pressure wave. A resonance state is also obtained when the pressure wave propagates so as to overlap with the pressure wave. Therefore, a resonance state is obtained even at an engine speed that is an integral multiple of the engine speed at which the above-described basic resonance state is obtained.

Also, the upstream end of the independent intake passage for each cylinder is connected to the expansion chamber as in the device shown in the above-mentioned Japanese Patent Publication No. 60-14169, etc., and the intake of each cylinder is performed at a specific rotational speed within the practical rotational speed range. In comparison with the configuration in which the inertial effect is provided by the independent intake passage (intake manifold branch) between the port and the expansion chamber, the length of the independent intake passage can be sufficiently reduced in the device of the present embodiment. . In other words, in the case of using the inertial effect of each independent intake passage, it is necessary to lengthen each independent intake passage to some extent so that the inertial tuning rotation speed by this independent intake passage is lower than the maximum allowable rotation speed of the engine. On the other hand, in the device of the present embodiment, since the inertial effect in the independent intake passages 6a to 6c is not relied on, the inertial tuning rotational speed by the independent intake passages 6a to 6c is set to be higher than the maximum allowable rotational speed of the engine. What is necessary is just to make the independent intake passages 6a to 6c sufficiently short. Specifically, the independent intake passage
Assuming that the length of 6a to 6c is l, the cross-sectional area of this passage is f, the cylinder volume is Vm, and the sound speed is a, the natural frequency ν by the independent intake passages 6a to 6c and the combustion chamber is When the valve opening period represented by the crank angle is θ, the inertia tuning rotation speed Ni by the independent intake passages 6a to 6c is (60 / Ni) · (θ / 360) = 1 / ν. Therefore, Ni = θ · ν / 6. Therefore, assuming that the maximum allowable engine speed is Nmax, Ni> Nmax Ni = θ · ν / 6 In this case, the lengths of the independent intake passages 6a to 6c may be sufficiently reduced. Since the resonance annular passage 5 common to each cylinder can be appropriately bent and relatively laid out even if the overall length is relatively long, the independent intake passages 6a to 6c provided for each cylinder as described above are provided. Reducing the length l is advantageous for making the entire intake system compact.

The specific structure of the device of the present invention is not limited to the above-described embodiment, but can be variously changed. Some examples are shown in FIGS.

In the embodiment shown in FIG. 3, relatively short independent intake passages 12a to 12c connected to the respective intake ports 3a to 3c are gathered, and the gathered portion is connected to the resonance annular passage 5. In this case as well, no enlarged portion is provided in the above-mentioned gathering portion between the resonance annular passage 5 and each of the intake ports 3a to 3c, and the resonance annular passage 5 has a pressure wave propagation path switching unit. On-off valve 8
Is provided. In the annular passage for resonance 5, a passage surface line S ₁ of a portion not serving as a flow passage of intake air sent from the intake introduction passage 7 to each cylinder is compared with a passage area S _{2 of a} portion serving as an intake flow passage. The pressure wave propagating through the resonance annular passage 5 is strengthened as much as possible. With this structure, substantially the same operation as in the first embodiment can be obtained.

FIG. 4 shows an embodiment in which the invention is applied to a four-cylinder engine. In this case as well, the intake ports 3a to 3d of the cylinders 2a to 2d are connected to the resonance annular passage 5.

In the embodiment shown in FIG. 5, an extended passage portion 5b bypassing a part of the passage portion 5a is connected to the resonance annular passage 5 to which the intake ports 3a to 3d are connected, and extends with the passage portion 5a. Passage
A switching valve 13 that switches between a state in which the passage portion 5a is opened and the extension passage portion 5b is closed and a state in which the extension passage portion 5b is opened and the passage portion 5a is closed is provided at a branch point with the passage portion 5b. According to this embodiment, when the switching valve is opened and closed according to the engine speed, the pressure wave propagation path passes through the annular path having a predetermined length passing through the passage section 5a and the extension path section 5b. It is switched to a long annular path, and a resonance effect by a pressure wave passing through the annular path is obtained in each of different rotational speed ranges. That is, the resonance effect is obtained by the annular path of a predetermined length passing through the passage portion 5a in the high speed region, and the resonance effect is obtained by the long annular path passing through the extension passage portion 5b in the low speed region.

Also in each of the embodiments shown in FIGS. 3 to 5, the length of the independent intake passage for each cylinder is set such that the inertia-tuned rotation speed of the independent intake passage is higher than the allowable rotation speed of the engine. It is formed short enough.

〔The invention's effect〕

As described above, according to the present invention, in the intake passage communicating with the intake port of each cylinder, the resonance annular passage for circulating the pressure wave propagating from each intake port is provided, so that the resonance state of the pressure wave can be obtained in a high speed region. The resonance annular passage is formed in the resonance annular passage, and a switching means for switching a pressure wave propagation path between the resonance annular passage and another path is provided. Is set so that a dynamic effect of the intake air is generated by obtaining the resonance state of the intake port, so that the charging efficiency can be increased by the dynamic effect in the high-speed range and the low-speed range, respectively. The pressure wave propagating from the cylinder and substantially circling around the resonance annular passage exerts a dynamic effect on each cylinder without causing a large imbalance after the cylinder, thereby effectively increasing the charging efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic view of an intake device showing one embodiment of the present invention, and FIG.
The drawings show pressure oscillations near the intake port, and FIGS. 3 to 5 are schematic views of an intake device showing another embodiment. 2a to 2c, 2a to 2d: cylinder, 3a to 4c, 3a to 3d: intake port, 5: annular passage for resonance, 8: on-off valve (switching means for pressure propagation path), 13: switching valve (Pressure propagation path switching means).

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiro Yuzuriha 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (56) References JP-A-56-52522 (JP, A)

Claims (1)

(57) [Claims] 1. An intake passage communicating with an intake port of each cylinder,
An annular annular passage is formed so as to circulate the pressure wave propagating from each intake port, and has a predetermined annular length for obtaining a resonance state of the pressure wave in a high-speed region. The engine speed and the natural frequency of the intake passage are synchronized in order to obtain the dynamic effect of the intake air in which the positive direction amplitude of the intake passage pressure immediately before the intake valve becomes large when the intake valve closes. In the above, the pressure wave propagates in the resonance annular passage, and in the low-speed region, a switching means for switching the pressure wave propagation path is provided so that the pressure wave propagates in a path different from the resonance annular path. Characterized in that the shape and size of the passage are set such that a resonance state of the pressure wave is obtained in a low-speed range and a dynamic effect of the intake occurs.