JPH0315779Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Field of industrial application) This invention connects each cylinder and the intake expansion chamber (tank) with mutually independent intake passages, and utilizes the dynamic effect of intake air (intake inertia effect). The present invention relates to an improvement of an intake system for a multi-cylinder engine designed to improve output.

(Prior Art) Conventionally, in the intake system of an engine, a negative pressure wave (pressure wave of negative pressure) generated with the start of intake is reflected at the opening end of the intake passage to the atmosphere or the intake expansion chamber on the upstream side of the intake passage, and a positive pressure wave ( The positive pressure wave returns to the intake port as a positive pressure wave, and the positive pressure wave reaches the intake port just before the intake valve closes, pushing the intake air into the combustion chamber. This is the so-called intake inertia. It is known to increase the filling efficiency of intake air by means of effects. When using such technology, if the shape of the intake passage is constant, the oscillation period of the pressure wave generated in the intake passage matches the opening and closing period of the intake valve, and the intake inertia effect is enhanced. Limited to a specific rotation range.

For this reason, conventionally, as seen in JP-A-56-115819, the length of the intake passage is changed depending on the engine speed, for example, the intake passage for each cylinder is divided into two parts at the upstream part. A long passage and a short passage are formed by branching, and the upstream ends of these passages are opened to an intake expansion chamber, etc., and a control valve is provided in the short passage, and the control valve is opened in a high rotation range. An intake device has been proposed in which the effective length of the intake passage is shortened (see FIG. 6 of the above-mentioned publication), thereby increasing the inertial effect of intake air in both the low-speed range and the high-speed range.

(Problems to be Solved by the Invention) By the way, as in the above-mentioned proposed example, there is a second intake passage that connects the intake expansion chamber (tank) and each cylinder independently of each other, and the middle of each independent intake passage communicates with the intake expansion chamber.
In an intake system for a multi-cylinder engine in which a passage is provided and a control valve that opens and closes in accordance with the operating state of the engine is provided in the second passage, when the control valve that opens and closes the second passage is closed (that is, at low engine speeds) In order to prevent the pressure waves propagating through each independent intake passage from leaking into the intake expansion chamber via the second passage,
Needless to say, the control valve needs to have an appropriate sealing property against the valve seat portion of the passage, and the second passage downstream of the control valve in the closed state has a dead volume that damps intake pulsation in each intake passage. Therefore, it is necessary to make this dead volume as small as possible in order to obtain an effective intake inertia effect in the low rotation range.

On the other hand, when the control valve is open (that is, in a high rotation range), the intake air flows smoothly from the intake expansion chamber to each independent intake passage via each second passage with little flow resistance. This is desired in order to effectively exhibit the intake inertia effect, and it is necessary to particularly consider the shape of the connecting portion of each second passage with the independent intake passage.

The present invention has been made to meet such requirements, and its purpose is to appropriately set the installation position of the control valve for each second passage and the shape of the connection part of each second passage with the independent intake passage. By doing so, while ensuring appropriate sealing performance of the control valve,
The dead volume that dampens intake pulsation when the control valve is closed is made as small as possible, and the flow of intake air from the second passage to the independent intake passage is made smooth when the control valve is closed. The aim is to effectively exert the intake inertia effect in each rotation range.

(Means for solving the problem) In order to achieve the above object, the solution of the present invention connects at least one space inside the tank and each cylinder through independent intake passages for each cylinder, which are independent from each other. In addition, a second passage is provided in the middle of each of the independent intake passages to communicate with a space inside the tank, and each of the second passages is provided with a control valve that opens and closes depending on the operating state of the engine. set to target. On the other hand, each of the control valves is installed at the connection portion of the second passage with the independent intake passage so that the valve body projects into the independent intake passage when the valve is open. moreover,
The shape of the connecting portion is set such that the distance between the closed control valve and the independent intake passage is large on the downstream side of the independent intake passage, and this downstream portion forms a smooth R-shaped curved surface. That is.

(Function) With the above configuration, in the present invention, when each second passage is closed by the control valve in the low engine speed range where the engine speed is less than the set value, the number of negative pressures propagating from each cylinder is reduced to each independent intake air. Since the positive pressure wave is reversed and reflected at the tank via the passage, the passage length from the tank to each cylinder is relatively long in order to obtain the intake inertia effect, and this makes the intake air flow in the low rotation range The inertial effect of On the other hand, in a high rotation range where the engine speed is higher than the set value, when each second passage is opened by the control valve, each cylinder communicates with the space inside the tank via the second passage in the middle of each independent intake passage.
The negative pressure waves propagating from each cylinder through this path are reversed and reflected into positive pressure waves, and
The effective length of the intake passage for obtaining the intake inertia effect is shortened, and the intake inertia effect in the high rotation range is enhanced.

In that case, the control valve is installed at the connection part of the second passage with the independent intake passage so as to protrude into the independent intake passage when the valve is closed, and the volume of the connection part when the valve is closed, that is, the dead volume. Since it is made as small as possible, it is possible to suppress attenuation of intake pulsation (attenuation of pressure waves) in each independent intake passage in a low rotation range. Moreover, the above-mentioned connection part is designed so that the distance between the control valve and the independent intake passage when the valve is closed is large on the downstream side of the independent intake passage, and this downstream part forms a smooth R-shaped curved surface. This setting allows the intake air to be guided from the second passage to the independent intake passage along the downstream side of the connection part when the control valve is opened, while ensuring good sealing performance when the control valve is closed. This enables smooth intake air to flow into the independent intake passage,
This ensures an improvement in the intake air filling efficiency in the high rotation range.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 to 4 show an embodiment in which the present invention is applied to a 4-cylinder, 4-stroke engine. In the figure, reference numeral 1 denotes an engine body consisting of a cylinder block 2, a cylinder head 3, etc. In the engine body 1, four cylinders 4, 4, 4, first to fourth, are arranged in series in the longitudinal direction. It is formed. A combustion chamber 5 is formed in each cylinder 4.

Reference numeral 6 denotes independent intake passages provided independently of each other for each cylinder, and each independent intake passage 6 is connected through an intake port 7 formed in the cylinder head 3 and constituting the downstream end of the independent intake passage 6. It opens into the combustion chamber 5 of each cylinder 4. Reference numeral 8 denotes an intake expansion chamber made of a substantially rectangular cylindrical tank extending parallel to the longitudinal direction of the engine.
It is partitioned vertically into a first volume chamber 8a having a relatively large volume on the upper side and a second volume chamber 8b having a relatively small volume on the lower side. The upstream ends of each of the independent intake passages 6, 6, . . . are connected to the first volume chamber 8a of the intake expansion chamber 8 with substantially the same passage length. The first volume chamber 8
An intake air introduction pipe 10 for introducing outside air is connected to one end surface of a, and a throttle valve 11 for controlling the amount of intake air is disposed inside the intake air introduction pipe 10. The intake air introduced into the first volume chamber 8a is supplied to the combustion chamber 5 of each cylinder 4 via each independent intake passage 6.
Further, the intake port 7 is provided with an intake valve 12 .

Further, a second passage 13 branches off from a midway point of each of the independent intake passages 6, and each of the second passages 1
The other ends of 3, 13, . Independent intake passages 6, 6...
are made to communicate with each other.

Further, each of the second passages 13 is provided with a control valve 14 that opens and closes the second passage 13,
Each control valve 14 has a valve shaft 15 whose valve body 14a extends parallel to the longitudinal direction of the intake expansion chamber 8.
Although not shown, the opening and closing of each independent intake passage by the second volume chamber 8b is controlled via an actuator by a control circuit that receives an output from an engine rotation speed detection means, etc. 6, 6... Control communication between them according to the engine operating state, so that they are closed in the low rotation range where the engine rotation speed is less than the set value, and are controlled to be opened in the high rotation range where the engine rotation speed is higher than the set value. be done. In addition, the control valve 1 according to such engine speed
The opening/closing operation of No. 4 may be performed at least during high loads where output is required, and the control valve 14 may be maintained in the open or closed state during low loads.

In such an intake system,
16 is the intake expansion chamber 8, each independent intake passage 6,
6... and each second passage 13, 13..., the structure 16 is an intake system structure for forming the intake expansion chamber 8 (the first volume chamber 8a and the second volume chamber 8).
b) The tank portion 17 constituting the tank portion 17
The independent intake passages 6, 17 extend around the tank part 17 from the upper part of the side opposite to the engine side to the side and lower sides, and utilize part of the constituent walls, that is, the side wall and the lower wall. integral intake pipe portions 18, 18, . A branch intake pipe section 19 extends from the lower side of each integrated intake pipe section 18, 18... toward the engine side and branches for each cylinder, forming the downstream portions 6b, 6b... of each independent intake passage 6, 6... , 19... and in the vicinity of the branched intake pipe section 19 of each integral intake pipe section 18, the lower wall of the constituent walls of the tank section 17 (second volume chamber 8b) is used to extend the middle of each independent intake passage 6. Communication pipe parts 20, 20... that integrally form the second passage 13 communicating with the second volumetric mass 8b, and each branch intake pipe part 1
9, 19..., and a flange portion 21 that connects the tip portions of each branch intake pipe portion 19 to the engine body 1 at the flange portion 21. 7, the bolts 22, 22... are inserted from the side and tightened to be fixed to the engine body 1. Further, the upper side of the tank portion 17 on the engine side is formed so as to bulge toward the engine side, so as to ensure a sufficient volume of the first volume chamber 8a.

Further, the downstream side portion 6b of the independent intake passage and each intake port 7 of each of the branched intake pipe portions 19 are formed to extend in a substantially straight line from obliquely upward toward the combustion chamber 5 and open into the combustion chamber 5. There is. and,
An injection valve mounting hole 23 is formed in the upper part near the downstream end of the downstream side portion 6b of the independent intake passage of each branch intake pipe section 19, and the fuel injection valve 24 has its tip injection port inserted through a seal ring 23a. It is inserted into the mounting hole 23 and fixed. The installation direction of the mounting hole 23 and the fuel injection valve 24 is such that the fuel from the injection valve 24 is injected toward the intake valve 12 of the combustion chamber 5, and each fuel injection valve 24, 24...
is connected to a fuel supply pipe 25 arranged parallel to the longitudinal direction of the engine. Due to this,
The fuel injection valve 24 is installed in a lying position almost along the branch intake pipe section 19, and the intake expansion chamber 8 is located on the extension line l of the center line of the fuel injection valve 24.
(Tank portion 17) is located close to fuel injection valve 24 and fuel supply pipe 25.

Furthermore, since the control valve 14 is disposed in the second passage 13 of each communication pipe section 20 and the intake expansion chamber 8 (tank section 17) is located on the central extension line l of the fuel injection valve 24, , the above-mentioned intake system structure 1
6 is located at a position below the center extension line 1 in the tank portion 17 and is connected to each of the second passages 13, 1.
A dividing plane along the longitudinal direction of the intake expansion chamber 8 at the position of the partition plate 9 between the second volume chamber 8b of the intake expansion chamber 8 including the second volume chamber 8b and the first volume chamber 8a of the intake expansion chamber 8. The upper divided body 16a is formed by being divided into upper and lower parts by the upper and lower parts, and the upper half of the tank part 17 and the upper half of each integral intake pipe part 18, 18 are integrally molded, and the lower half of the tank part 17. part, the lower half part of the integral intake pipe part 18, 18..., each branch intake pipe part 19,
19..., each communicating tube part 20, 20... and a lower divided body 16b integrally formed with a flange part 21, both divided bodies 16a, 16b are joined via the partition plate 9, and bolts 26, 26 ... are inserted from below and tightened to form an airtight connection.

In addition, each communication pipe portion 2 of the intake system structure 12
0, each of the control valves 14 is connected to the second passage 13.
As shown by the imaginary line in FIG. 1, substantially the lower half of the valve body 14a is in tension with the independent intake passage 6 when the valve body 14a is in the open state, as shown by the imaginary line in FIG. It is set up to come out. Further, as shown in FIG. 1, each of the second passages 13 is formed in communication with the independent intake passage 6 so that its center line p intersects with the independent intake passage 6 at a predetermined acute angle θ smaller than 90°. Furthermore, the connecting portion 2 of each of the second passages 13 is
7 is the shape of the second seat seated when the control valve 14 is closed.
The distance from the valve seat portion 13a of the passage 13 to the independent intake passage 6, that is, the interval between the control valve 14 in the closed state and the independent intake passage 6, is smaller in the upstream portion 27a than the independent intake passage 6, and is on the downstream side. The downstream portion 27b is set to have a large radius of curvature and a smooth R-shaped curved surface.

Incidentally, as shown in detail in FIG. 4, the tank section 1
7 (second volume chamber 8b), each second passage 1
Boss portions 28, 28, . Control valve 14
Rib portions 29, 29... which protrude in an annular shape so as to connect the boss portions 28, 28 in series are integrally formed on the valve seat portion on which the valve body 14a is seated, and the rib portions 29, 29... The rigidity of the intake expansion chamber 8 (tank section 17) in the longitudinal direction of the engine is increased by the boss sections 28, 28, . Further, as shown in FIG. 4, the second passage 13 is drilled from the second volume chamber 8b side, and the connection part 27 of the second passage 13 with the independent intake passage is formed into a smooth rounded part. This structure suppresses the change in the passage cross-sectional area of the second passage 13 to a small and gentle one, and reduces the flow resistance from the second volume chamber 8b to the independent intake passage 6 via the second passage 13 and its change. I'm trying to keep it down.

Next, to describe the operation of the above embodiment, each control valve 14 closes and the second passage 13 is closed, thereby cutting off communication between the independent intake passages 6, 6, . . . by the second volume chamber 8b. In this state, the negative pressure waves generated during the intake stroke of each cylinder 4 are propagated to the first volume chamber 8a and reflected there. In other words, the negative pressure waves and their reflected waves propagate through a relatively long passage, so that the low rotation range The oscillation cycle of such pressure waves matches the intake valve opening/closing cycle, thereby increasing the smoothness of the intake air in the low rotation range and increasing the intake air filling efficiency. On the other hand, each of the control valves 14 is opened and the second passage 13 is opened,
When the independent intake passages 6, 6... are in communication with each other through the second volume chamber 8b, negative pressure waves generated during the intake stroke of each cylinder 4 are reflected at the second volume chamber 8b via the second passage 13. By shortening the length of the passage provided for the propagation of negative pressure waves and reflected waves, the intake inertia effect is enhanced in the high rotation range, and in this operating range, the pressure waves propagated from other cylinders are also This effectively acts through the two-volume chamber 8b, greatly increasing the filling efficiency in the high rotation range. Therefore, at least when the load is high, the control valve 14 is activated on the lower rotation side after a predetermined rotation speed corresponding to the intermediate rotation speed between the respective rotation speeds at which the intake inertia effect between the low rotation range and the high rotation range is obtained. By closing the control valve 14 and opening the control valve 14 at higher rotation speeds, the intake air filling efficiency can be increased over the entire rotation range and the output can be improved. In particular, the intake air filling efficiency in the high rotation range can be further improved by the pressure propagation effect between the cylinders, compared to the conventional case where the intake passage was simply shortened to increase the inertia effect. .

The sizes of the first and second volume chambers 8a and 8b that are suitable for effectively exerting the above-mentioned effects are such that the first volume chamber 8a has a capacity of 0.5 times or more of the displacement, and the second volume It is desirable that the capacity of the chamber 8b is 1.5 times or less than the exhaust volume. Further, it is desirable that the second volume chamber 8b has a smaller capacity than the first volume chamber 8a, and that the cross-sectional area of the second volume chamber 8b is larger than the cross-sectional area of each independent intake passage 6.

In this case, the tank portion 17 that constitutes the intake expansion chamber 8 (the first volume chamber 8a and the second volume chamber 8b) in the intake system structure 16 and the integrated intake that constitutes the upstream portion 6a of each independent intake passage 6 Pipe part 18
The branch intake pipe section 19 that constitutes the downstream portion 6b of each independent intake passage 6 and the communication pipe section 20 that constitutes each second passage 13 allow each independent intake passage 6 to extend around the intake expansion chamber 8. While detouring and intake expansion chamber 8
(tank part 17), and each second passage 13 is integrally formed with a part of the wall that constitutes the intake expansion chamber 8 (second volume chamber 8b). Therefore, in order to obtain the required length of the independent intake passage 6 and the required volumes of the first and second volume chambers 8a and 8b of the intake expansion chamber 8, these intake systems can be made compact and small. Therefore, the above-mentioned required length and required volume can be sufficiently secured within a limited space (engine room), and the vehicle mountability can be improved.

Further, in this case, the fuel injection valve 24 is arranged near the downstream end of the branched intake pipe section 19, that is, on the downstream side of the independent intake passage 6, in order to supply the injected fuel to the combustion chamber 5 with good responsiveness while improving its atomization. Since the fuel injector 24 is mounted facing the combustion chamber 5, the intake system structure 1 is located close to the central extension line l of the fuel injector 24.
It is necessary that the tank portion 17 (intake expansion chamber 8) of No. 6 be located therein, and that the control valve 14 be disposed in each of the second passages 13. Therefore, in this example,
The intake system structure 16 has a dividing surface along the longitudinal direction of the intake expansion chamber 8 at a position below the center extension line 1, that is, on the side of the branch intake pipe section 19 in the tank section 17, and at the position of the partition plate 9. Since the upper and lower divided bodies 16a and 16b are vertically divided into an upper divided body 16a and a lower divided body 16b, and both divided bodies 16a and 16b are connected via the partition plate 9, the lower divided body 10b is
After attaching to the engine body 1 by tightening the bolts 22 from the side, the lower divided body 16
Each fuel injection valve 24 is inserted into the injection valve mounting hole 23 of each branch intake pipe portion 19 of b from the direction of the center extension line l, and the fuel supply pipe 25 is fixed to the lower division body 16b. At the same time, the second passage 13 of each communication pipe portion 20 of the lower divided body 16b is attached.
The valve body 14a of the control valve 14 is inserted from above and fixed to the valve shaft 15, and then the upper divided body 16a is joined to the lower divided body 16b with the partition plate 9 interposed therebetween, and then inserted from below. bolt 26
By joining the two parts 16a and 16b together by tightening, it is possible to ensure good formability and to easily assemble the upper and lower divided bodies 16a and 16b. The valve 14 and the fuel injection valve 24 can be easily assembled, and good assembly performance can be ensured.

Moreover, the upper divided body 16a and the lower divided body 1
6b is achieved by tightening the bolt 26 from below, while ensuring good assemblability, the upper part of the side of the tank part 17 (intake expansion chamber 8) on the engine side is secured as described above. There is also the advantage that a sufficient volume of the intake expansion chamber 8, particularly the first volume chamber 8a, can be secured. Further, the second volume chamber 8b is arranged in parallel with the first volume chamber 8a by dividing the tank portion 17 of the intake system structure 16 into upper and lower parts with a partition plate 9, and is arranged in parallel with the first volume chamber 8a.
Since a part of the constituent wall (partition plate 9) is shared, the intake system can be made more compact.

Further, each of the control valves 14 is installed at the connecting portion 27 of the second passage 13 with the independent intake passage 6 so that the valve body 14a extends into the independent intake passage 6 when the valve is open. When the valve is closed, the volume of the connecting portion 27, that is, the dead volume, is small when the connecting portion 27 is in a state close to the independent intake passage 6. As a result, in the low rotation range where the control valve 14 is closed, the intake pulsation in the independent intake passage 6 is suppressed from being attenuated, and the attenuation of pressure waves can be suppressed. It is possible to effectively utilize the intake inertia effect in the region without reducing it.

Further, each of the second passages 13 communicates with the independent intake passage 6 at an acute predetermined angle θ, and the connection portion 27 of the second passage 13 with the independent intake passage 6 is controlled to close the valve. The distance between the valve 14 and the independent intake passage 6 is larger in the downstream portion 27b than the independent intake passage 6, and
is formed into a smooth R-shaped curved surface, so that in the high rotation range when the control valve 14 is open, the intake air from the second volume chamber 8b flows into the second passage 13 and the connecting portion 27, especially the downstream portion 27 thereof. The intake air is smoothly introduced into the independent intake passage 6 along the line, and the flow of intake air from the second passage 13 to the independent intake passage 6 is smooth.
Therefore, the intake inertia effect in the high rotation range is effectively exhibited, and improvement in intake air filling efficiency can be ensured.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, as in the above embodiment, the intake expansion chamber 8 is divided into a first volume chamber 8a and a second volume chamber 8b to obtain intake inertia effects in the low rotation range and high rotation range, and particularly in the high rotation range. In addition to the intake system that further increases the filling efficiency of intake air by propagating pressure waves between cylinders, as shown in FIG. An intake system that increases the intake inertia effect in the low rotation range and high rotation range, or a communication hole in the partition plate 9 in the above embodiment that communicates the upper and lower first volume chamber 8a and second volume chamber 8b. The present invention can also be applied to an intake system in which the intake air filling efficiency is further increased by utilizing intake air pressure vibration between the upper and lower volume chambers 8a and 8b in a low rotation range.

Furthermore, it goes without saying that the present invention is not limited to the four-cylinder engine as in the embodiments described above, but can also be applied to other multi-cylinder engines, such as five-cylinder engines and six-cylinder engines.

(Effects of the invention) As explained above, according to the invention, in addition to the independent intake passages leading from at least one space inside the tank to each cylinder, the middle of each independent intake passage communicates with the space inside the tank. In an intake system for a multi-cylinder engine in which the second passage is opened and closed by a control valve to obtain an intake inertia effect in a low rotation range and a high rotation range, the second passage is connected to the independent intake passage. The above-mentioned control valve is installed so that the valve body protrudes into the independent intake passage when the valve is opened, and the shape of the above-mentioned connection part is changed so that the distance between the control valve in the closed state and the independent intake passage is adjusted to the downstream side of the independent intake passage. Since the downstream part is set to have a smooth R-shaped curved surface, it ensures good sealing performance when the control valve is closed, while reducing the volume of the connection part when the control valve is closed. In other words, it is possible to reduce the dead volume as much as possible to suppress the attenuation of pressure waves in the low rotation range, and also to smooth the flow of intake air from the second passage to the independent intake passage when the control valve is opened. Therefore, the intake inertia effect can be effectively exerted in the low rotation range and the high rotation range.

[Brief explanation of drawings]

1 to 4 show embodiments of the present invention.
The figure is a longitudinal sectional side view taken along the - line in Figure 3.
The figure is a longitudinal sectional side view taken along the - line in Figure 3.
The figure is a partially cutaway plan view, and Figure 4 is the same as Figure 1.
FIG. FIG. 5 is a diagram corresponding to FIG. 1 showing another embodiment. 1... Engine body, 4... Cylinder, 6... Independent intake passage, 8... Intake expansion chamber, 8a... First volume chamber, 8b... Second volume chamber, 13... Second passage, 1
4... Control valve, 16... Intake system structure, 17...
Tank part, 18... Integral intake pipe part, 19... Branch intake pipe part, 20... Communication pipe part, 27... Connection part,
27b...downstream part.

Claims (1)

[Scope of utility model registration request] Connecting at least one space inside the tank and each cylinder through independent intake passages for each cylinder that are independent from each other, and providing a second passage that communicates the middle of each independent intake passage with the space inside the tank,
In the intake system for a multi-cylinder engine in which each of the second passages is provided with a control valve that opens and closes depending on the operating state of the engine, each of the control valves has an open state at the connection portion of the second passage with the independent intake passage. The valve body is installed so as to protrude into the independent intake passage, and the shape of the connection part is such that the distance between the control valve in the closed state and the independent intake passage is large on the downstream side of the independent intake passage.
An intake system for a multi-cylinder engine, characterized in that the downstream portion thereof is set to have a smooth R-shaped curved surface.