JPH0427370B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention connects each cylinder and an intake expansion chamber (tank) through independent intake passages, thereby utilizing 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, the negative pressure number (pressure wave of negative pressure) generated with the start of intake is reflected at the open 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 is generated. By utilizing the fact that the positive pressure wave becomes a positive pressure wave and returns toward the intake port, the positive pressure wave reaches the intake port just before the intake valve closes and forces the intake air into the combustion chamber. It is known to increase the filling efficiency of intake air through inertial 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 this 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 communicates with the intake expansion chamber in the middle of each independent intake passage.
In an intake system for a multi-cylinder engine in which a passage is provided and a control valve is provided in the second passage to open and close depending on the operating state of the engine, the intake expansion chamber (tank) has a shape extending parallel to the longitudinal direction of the engine. Because of this, the tank tends to vibrate and deform along the longitudinal direction of the engine as the engine vibrates.
This makes it difficult to smoothly open and close the control valve that opens and closes the second passage, resulting in a problem that the intake inertia effect cannot be achieved in the low and high rotation ranges as described above.

The present invention has been made in view of the above, and an object of the present invention is to reinforce an intake expansion chamber (tank) with a valve shaft of a control valve and a support portion that supports the valve shaft. Accordingly, the purpose is to sufficiently and effectively ensure the rigidity of the tank constituting the intake expansion chamber, suppress vibrations of the tank due to engine vibrations, and thereby ensure smooth opening and closing of the control valve.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is to separate at least one space formed inside a tank extending in the cylinder row direction and each cylinder into independent cylinders. A control valve is provided in each of the second passages, which is connected to each other by separate independent intake passages, and which communicates with the space inside the tank in the middle of each of the independent intake passages, and which opens and closes depending on the operating state of the engine. The target is the intake system of a multi-cylinder engine equipped with a On the other hand, the boss part that supports the valve shaft of the control valve is formed integrally with the constituent wall of the tank, and the boss part of the tank is surrounded by the entire circumferential direction of the valve shaft. The wall portions of the second passage are connected to each other by extending continuously in the direction of the cylinder row along the constituent wall.

(Function) With the above configuration, in the present invention, when each second passage is closed by the control valve in a low engine speed range where the engine speed is less than a set value, negative pressure waves propagating from each cylinder are transmitted to each independent intake passage. As a result, the passage length from the tank to each cylinder is relatively long in order to obtain the intake inertia effect, and this reduces the intake air flow in the low rotation range. The inertia effect is enhanced. 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 that propagate from each cylinder via this path are reversed and reflected as positive pressure waves, and the effective length of the intake passage to obtain the intake inertia effect is shortened, resulting in a reduction in speed in the high rotation range. The effect of inhalation inertia will be enhanced.

In this case, the boss part that supports the valve shaft of the control valve is formed integrally with the wall that constitutes the tank, and the boss part that supports the valve shaft of the control valve is formed integrally with the wall that constitutes the tank, and the boss part that supports the valve shaft of the control valve is formed so as to surround the entire circumferential direction of the valve shaft. Since the walls of the second passage are connected to each other by extending continuously in the direction, the structure of the second passage is made compact, and it is possible to extend continuously along the tank-constituting wall and to connect the walls of the second passage with each other. The rigidity of the tank in the cylinder row direction is increased by the boss part and the valve shaft which is supported over the entire circumferential direction by the boss part and extends along the tank wall. , vibration deformation of the tank due to engine vibration is effectively suppressed, making it possible to always open and close the control valve smoothly.

(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-cycle 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 suppressing the intake chamber air volume is disposed inside the intake air introduction pipe 10. Thus, 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 of the control valves 14 is integrally fixed to a valve shaft 15 that extends in parallel with the longitudinal direction of the intake expansion chamber 8, and is connected to a control circuit (not shown) that receives output from an engine rotation speed detection means, etc. is controlled to open and close via an actuator, and communication between the independent intake passages 6, 6... by the second volume chamber 8b is controlled according to the engine operating state, and in a low rotation range where the engine rotation speed is less than a set value. It is controlled to be closed and opened in the high engine speed range where the engine speed is higher than a set value. Note that the opening/closing operation of the control valve 14 according to the engine speed is as follows.
It suffices to perform this at least during high loads when output is required, and at low loads, the control valve 1
4 may be kept open or closed.

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 part 17 constituting the tank part 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
The flange portion 21 connects the tips of the branch intake pipe portions 19 to the engine body 1, and the downstream portion 6b of the independent intake passage of each branch intake pipe portion 19 is connected to the intake port of each cylinder 4. 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, thereby ensuring 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 state almost along the branched intake pipe portion 19, and the intake expansion chamber 8 is located above the extension line q 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.

Further, 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 above the central extension line q of the fuel injection valve 24. From above, the above-mentioned intake system structure 1
6 is located at a position below the center extension line q→ in the tank portion 17 and is connected to each of the second passages 13, 1.
Division 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 a surface, 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 upper divided body 16a of the tank part 17 Lower half part, lower half part of integral intake pipe parts 18, 18..., each branch intake pipe part 1
9, 19..., each communicating pipe part 20, 20... and a lower divided body 16b in which the flange part 21 is integrally molded, 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, as shown in detail in FIG. 4, on the lower wall of the tank portion 17 (second volume chamber 8b), there are holes between the openings of each second passage 13 to the second volume chamber 8b and at both ends. The boss portions 27, 27, . Rib portions 28, 28... which protrude in an annular manner so as to connect the boss portions 27, 27 in series are integrally formed, and the continuous boss portions 27, 27... are formed integrally with each other through the rib portions 28, 28... Intake expansion chamber 8
The rigidity of the tank portion 17 in the longitudinal direction of the engine is increased. As shown in FIG. 4, the second passage 13 is drilled from the second volume chamber 8b side, and the connection part of the second passage 13 with the independent intake passage is formed into a smooth rounded part. do,
The change in the passage cross-sectional area of the second passage 13 is suppressed to a small and gentle one, and the passage from the second volume chamber 8b to the second passage 1
3 and the flow resistance to the independent intake passage 6 and its change are kept small. Also,
29 is formed along the boss portion 27 and is connected to the second passage 1
This is a rib portion that connects the annular rib portions 28, 28 around the three openings.

Next, to describe the operation of the above embodiment, each control valve 14 closes and the second passage 13 is closed, thereby cutting off the communication between the independent intake passages 6, 6, . . . by the second volume chamber 8b. In this condition, each cylinder 4
The negative pressure wave generated during the intake stroke is propagated to the first volume chamber 8a and reflected there. In other words, the negative pressure wave and its reflected wave propagate through a relatively long passage, so that such a pressure wave is generated in the low rotation range. The vibration period matches the intake valve opening/closing period, increasing the inertial effect of intake air in the low rotation range and increasing intake air filling efficiency. On the other hand, each control valve 14 is opened, the second passage 13 is opened, and each independent intake passage 6, 6 is opened by the second volume chamber 8n.
...When they are in communication with each other, the negative pressure waves generated during the intake stroke of each cylinder 4 are reflected in the second volume chamber 8b via the second passage 13, and the negative pressure waves and reflected waves are propagated. By shortening the passage length, the intake inertia effect is enhanced in the high rotation range, and in this operating range, pressure waves propagated from other cylinders also act effectively through the second volume chamber 8b. This greatly increases charging 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. Furthermore, 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 center extension line q 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, the intake system structure 16 is located in the tank portion 17 at a position below the center extension line q→, that is, on the branch intake pipe portion 19 side, and at the position of the partition plate 9 in the longitudinal direction of the intake expansion chamber 8. It is vertically divided into an upper divided body 16a and a lower divided body 16b along the dividing plane, and both divided bodies 16a, 1
6b are connected via the partition plate 9, after the lower divided body 16b is attached to the engine body 1 at its flange portion 21 by tightening bolts 22 from the side, the lower divided body 16b is The fuel injection valve 2 is inserted into the injection valve mounting hole 23 of each branch intake pipe section 19.
4 from the center extension line q → direction and insert the fuel supply pipe 25
By fixing the fuel injection valves 24 to the lower divided body 16b, each fuel injection valve 24 is attached, and the lower divided body 1
The control valve 14 is inserted into the second passage 13 of each communication pipe portion 20 of 6b from above and fixed to the valve shaft 15, and then the upper divided body 16b is separated by interposing the partition plate 9 with respect to the lower divided body 16b. By joining the body 16a and tightening the bolt 26 from below, both 16
By integrally joining a and 16b, good moldability is ensured, and the upper and lower divided bodies 1
6a and 16b can be easily assembled, as well as the control 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.

Furthermore, the tank section 17 (second volume chamber 8b)
Boss portions 27, 27, . , 27... are connected in series by the annular rib portions 28, 28... integrally formed around the opening of each second passage 13, so that the engine longitudinal direction of the intake expansion chamber 8 (tank portion 17) The rigidity strength in the direction will be enhanced. Therefore, the tank part 17 due to engine vibration
The vibration deformation of the control valve 14 is suppressed as much as possible, and the opening and closing of the control valve 14 is not hindered as in the past, and its smooth opening and closing operation is stably ensured, which reduces the intake inertia effect mentioned above. performance can be ensured. Further, by integrally forming the boss portion 27 and the rib portion 28 on the wall constituting the tank portion 17, the structure can be made compact and simple.

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 above-described embodiments, 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 present invention, in addition to the independent intake passage extending from at least one space inside the tank extending in the cylinder row direction to each cylinder, the tank In an intake system for a multi-cylinder engine in which a second passage communicating with an internal space 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 valve shaft of the control valve is The supporting boss portion is formed integrally with the tank wall, and extends continuously in the cylinder row direction along the tank wall while surrounding the entire valve shaft in the circumferential direction. Since the walls of the second passage are connected to each other by the boss, the structure can be made more compact, and the rigidity of the tank in the direction of the cylinder row can be ensured to ensure good rigidity and strength, and the expansion of the intake chamber due to engine vibration can be avoided. It is possible to effectively suppress vibrations, thereby ensuring smooth opening and closing of the control valve, and ensuring that the intake inertia effect is exerted in the above-mentioned low rotation range and high rotation range. be.

[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, 15... Valve shaft, 16...
...Intake system structure, 17...Tank part, 18...Integrated intake pipe part, 19...Branch intake pipe part, 20...Communication pipe part, 27...Boss part, 28...Rib part.

Claims (1)

[Claims] 1 At least one space formed inside a tank extending in the direction of the cylinder row and each cylinder are connected by each independent intake passage for each cylinder, and the middle of each independent intake passage is connected to a space inside the tank, respectively. In an intake system for a multi-cylinder engine, the boss portion supporting the valve shaft of the control valve is provided with a second passage communicating with the engine, and each second passage is provided with a control valve that opens and closes depending on the operating state of the engine.
The valve shaft is formed integrally with the constituent wall of the tank, and extends continuously in the direction of the cylinder row along the constituent wall of the tank while surrounding the entire circumferential direction of the valve shaft. An intake system for a multi-cylinder engine characterized by connecting the walls of two passages.