JPH0343379Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention uses the dynamic effect of intake air (intake inertia effect) to generate output in a multi-cylinder engine in which each cylinder and intake expansion chamber are connected by independent intake passages. The present invention relates to an improvement of an intake system for a multi-cylinder engine in order to improve the performance of the multi-cylinder engine.

(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, as seen in Japanese Patent Application Laid-Open No. 56-115819, the length of the intake passage is changed depending on the engine speed, for example, the intake passage for each cylinder is bifurcated at the upstream part. They are branched to form a long passage and a short passage, and the upstream ends of these passages are opened to an intake expansion chamber, etc., and an on-off valve is provided in the short passage, and this on-off valve is opened in the high rotation range to increase the intake air. An intake device has been proposed in which the effective length of the passage is shortened (see FIG. 6 of the above-mentioned publication), thereby increasing the inertial effect of intake air in both the low rotation range and the high rotation range.

(Problem to be solved by the invention) By the way, according to the above-mentioned conventional intake system, in the case of a multi-cylinder engine, even though pressure waves are generated in each cylinder, in the high rotation range, the intake system is simply By shortening the effective length of the passage, etc., the intake inertia effect is simply increased by pressure wave propagation between each cylinder and the upstream opening end of the corresponding intake passage, and the intake air filling efficiency is improved. There is room for That is, if pressure waves generated in other cylinders are also effectively utilized, it is expected that the filling efficiency can be further improved.

Therefore, the present invention was developed with attention to this point, and by changing the effective length of the intake passage for each cylinder, the inertia effect of the intake air is increased in the low rotation range and the high rotation range, respectively. In particular, in the high rotation range where high output is required, pressure waves generated in other cylinders are effectively used between each cylinder to further increase intake air filling efficiency in the high rotation range and improve output. The purpose is to

Furthermore, an object of the present invention is to make the shape and structure of this intake system as compact and small as possible in order to obtain an intake system that performs the above-mentioned functions, thereby improving vehicle mountability.

Furthermore, in the above-mentioned intake system,
Generally, EGR gas (exhaust gas recirculation gas) or blow-by gas is introduced into the intake expansion chamber in order to ensure good distribution to each cylinder. As a result, moisture contained in these gases accumulates in the intake expansion chamber, leading to corrosion of the wall (tank) that constitutes the intake expansion chamber.
Particularly in engines using leaded gasoline as fuel, corrosion is significant because oxidizing substances are produced in the moisture. Therefore, another object of the present invention is to prevent corrosion of the tank by taking measures to drain the water.

(Means for Solving the Problems) In order to achieve the above object, the solution of the present invention provides a multi-channel system in which the upstream ends of the independent intake passages provided independently for each cylinder are each connected to an intake expansion chamber. This assumes an intake system for a cylinder engine. and,
A midway portion of each of the independent intake passages is connected to a communication portion that branches upward from the midway portion of each independent intake passage and communicates the independent intake passages with each other. An opening/closing valve is disposed at a branching portion of the communication portion from each of the independent intake passages, and the valve closes the communication between the independent intake passage and the communication portion in a low rotation range of the engine, and opens the communication in a high rotation range of the engine. ing. The above-mentioned intake expansion chamber and communication section are:
By partitioning the tank with a partition part, the upper side of the partition part in the tank is formed as an intake expansion chamber, and the lower side is formed as a communication part, and the communication part is arranged below the intake expansion chamber. , and the volume of the communication portion is set smaller than the volume of the intake expansion chamber.
The partition section that partitions the intake expansion chamber and the communication section is provided with a drain hole for draining moisture that has flowed into the intake expansion chamber into the communication section.

(Function) With the above configuration, in the present invention, in the low engine speed range where the engine speed is less than the set value, if the on-off valve closes the communication between the independent intake passages through the communication part, the air will propagate from each cylinder. Since the negative pressure wave that occurs is reversed and reflected as a positive pressure wave in the intake expansion chamber, the passage length required to obtain the intake inertia effect is relatively long from the intake expansion chamber to each cylinder. The inertial effect of intake air in the rotation range is enhanced.

On the other hand, in a high engine speed range where the engine speed is higher than the set value, if each independent intake passage is communicated with each other via the communication part by the on-off valve, the negative energy propagated from each cylinder at the communication part in the middle of each independent intake passage Since the pressure waves are inverted and reflected into positive pressure waves, the effective length of the intake passage for obtaining the intake inertia effect becomes shorter. Moreover, pressure waves from other cylinders are propagated through the communication portion, and the synergistic effect of these pressure waves greatly increases the filling efficiency in the high rotation range.

In this case, the communication section may be connected to the intake expansion chamber, which is arranged parallel to the longitudinal direction of the engine so that the passage lengths of the independent intake passages are the same, by partitioning the tank with a partition section. The upper side of the partition is formed as an intake expansion chamber, and the lower side is formed as a communication section, which are arranged side by side on the lower side of the intake expansion chamber, so the passage length from each cylinder to the communication section branch point in the middle of each independent intake passage It becomes possible to form a small and compact intake system while effectively ensuring the above-mentioned effect by keeping the same.

Furthermore, when EGR gas, etc. is introduced into the intake expansion chamber to ensure good distribution to each cylinder, the moisture contained in this EGR gas, etc. is transferred to the partition between the intake expansion chamber and the communication section. Water is drained into the communication section through the provided water drain hole, and is supplied to each cylinder from this communication section for evaporation treatment, so the moisture does not accumulate in the intake expansion chamber, and the walls that make up the intake expansion chamber It becomes possible to prevent corrosion.

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

1 to 3 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. The upstream ends of these independent intake passages 6, 6, . It is connected in communication. An intake air introduction pipe 9 for introducing outside air is connected to one end surface of the intake expansion chamber 8, and a throttle valve 10 for controlling the amount of intake air is disposed inside the intake air introduction pipe 9. Intake air introduced into the intake expansion chamber 8 through the introduction pipe 9 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 11 .

The intermediate portion of each independent intake passage 6 extends parallel to the intake expansion chamber 8 (that is, the longitudinal direction of the engine),
These independent intake passages 6, 6, . . . are connected to a communication portion 13 through which the independent intake passages 6, 6, . Moreover, by this, each cylinder 4 is
The passage lengths up to the two are set to be approximately the same length.

Each branch hole 12 is provided with an on-off valve 14 that opens and closes the branch hole 12, respectively. Each of the on-off valves 14 is integrally fixed to a valve shaft 15 extending in the longitudinal direction of the communication portion 13 so as to be interlocked with each other, and although not shown, the actuator is controlled by a control circuit that receives an output from an engine rotation speed detecting means or the like. The communication between the independent intake passages 6 through the communication portion 13 is controlled according to the engine operating state, and is closed in the low rotation range where the engine rotation speed is less than the set value, and the engine rotation speed is set. A control means 27 is configured to open the valve in a high rotation range exceeding the value. Note that the opening/closing operation of the on-off valve 14 according to the engine speed may be performed at least during high loads that require a small output, and the on-off valve 14 may be opened/closed at low loads.
may be kept open or closed.

In such an intake system,
16 is the intake expansion chamber 8, each independent intake passage 6,
6..., an intake system structure for forming the communication portion 13 and each branch hole 12, 12.... The structure 1
Reference numeral 6 denotes a tank section 17 that includes the intake expansion chamber 8 and the communication section 13 separated by a partition plate 28.
The tank portion 17 extends from the upper side of the tank portion 17 opposite to the engine side to the side and lower sides.
The upstream portions 6a, 6a, . 17 (intake expansion chamber 8) Integral intake pipe parts 18, 18... integrally formed so as to open at the upper side of the side, and the respective integrated intake pipe parts 18, 18...
Branch intake pipe portions 19, 1 extend from the lower side toward the engine side and branch for each cylinder, forming downstream portions 6b, 6b of each independent intake passage 6, 6...
9... and each independent intake passage 6 using the lower wall of the constituent walls of the tank section 17 (communication section 13) in the vicinity of the branch intake pipe section 19 of each integral intake pipe section 18.
It consists of communication pipe parts 20, 20... which integrally form a branch hole 12 which communicates with the communication part 13 in the middle thereof, and a flange part 21 which connects the tips of each of the branch intake pipe parts 19, 19... to each other. , the flange portion 21
With the independent intake passage downstream portion 6b of each branch intake pipe section 19 aligned with the intake port 7 of each cylinder 4 with respect to the engine body 1, bolts 22, 22...
It is fixed to the engine body 1 by inserting it from the side and tightening it. Further, the upper side of the tank portion 17 on the engine side is formed so as to bulge toward the engine side, thereby ensuring a sufficient volume of the intake expansion chamber 8. That is, since the tank part 17 is formed so that the communication part 13 and the intake expansion chamber 8 both extend parallel to the longitudinal direction of the engine, by dividing the tank part 17 into upper and lower parts by the partition plate 28 as a partition part, An intake expansion chamber 8 with a relatively large capacity is defined above the partition plate 28 in the tank section 17, and a communication section 13 with a relatively small capacity is defined below.
It is formed by a part of the constituent wall (partition plate 28) constituting the air intake expansion chamber 8, and is arranged below the intake expansion chamber 8.

Further, the independent intake pipe passage downstream portion 6b of each branch intake section 19 and each intake port 7 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. Injection valve mounting hole 2
3 and is fixed. The injection valve mounting hole 23 and the fuel injection valve 24 are installed in such a manner that the fuel from the injection valve 24 is injected toward the intake valve 11 of the combustion chamber 5. ... are connected to a fuel supply pipe 25 arranged parallel to the longitudinal direction of the engine. As a result, the fuel injection valve 24 is connected to the branch intake pipe section 1.
9, and the tank portion 17 is located close to the fuel injection valve 24 and the fuel supply pipe 25 on an extension of the center line of the fuel injection valve 24.

Further, an on-off valve 14 is disposed in the branch hole 12 of each communication pipe section 20, and a tank section 17 is provided.
is located on the central extension line of the fuel injection valve 24, so that the intake system structure 16 is positioned below the central extension line of the fuel injection valve 24 in the tank portion 17 and at each branch. hole 12,1
It is formed by being divided into upper and lower parts by a dividing plane along the longitudinal direction of the tank part 17 at the position of the partition plate 28 between the part of the communication part 13 including 2... and the intake expansion chamber 8, and An upper divided body 16a in which the upper half of the section 17 (intake expansion chamber 8) and the upper half of each integral intake pipe section 18, 18... are integrally molded, the lower half of the tank section 17 (the communication section 13), The lower half of the integrated intake pipe parts 18, 18..., each branched intake pipe part 19, 1
9..., each communicating pipe line 20, 20... and a lower divided body 16b integrally formed with a flange portion 21, both divided bodies 16a, 16b... are joined via a partition plate 28, and bolts 26, 26 ... are inserted from below and tightened to form an airtight connection.

In addition, as shown in FIG. 2, the partition plate 28 serving as a partition part that partitions the intake expansion chamber 8 and the communication portion 13 has an opening/closing function near the lower height side (engine side) of the partition plate 28. A drain hole 29 is formed at a position corresponding to an intermediate location between the branch holes 12 and 12 so as not to face the valve 14.

Next, to describe the operation of the above embodiment, each on-off valve 14 is closed by the control means 27 and the communication portion 1 is closed.
In a state in which the communication between the independent intake passages 6 is closed due to the passage 3, the negative pressure waves generated during the intake stroke are propagated to the intake expansion chamber 8 and reflected there. In other words, the negative pressure waves and their Due to the propagation of the reflected waves, the oscillation period of these pressure waves matches the intake valve opening/closing period in the low rotation range, increasing the inertia effect of intake air in the low rotation range and increasing the intake air filling efficiency. be enhanced. On the other hand, each on-off valve 14 is controlled by the control means 27.
is opened and the individual intake passages 6 are in communication with each other through the communication portion 13, the negative pressure waves generated during the intake stroke are reflected by the communication portion 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 communication part 13, resulting in high engine speed. Filling efficiency in the rotation range is greatly increased. Therefore, at least when the load is high, the opening/closing valve 14 is opened at a lower rotational speed than a predetermined rotational speed corresponding to an intermediate rotational speed between the respective rotational speeds at which the intake inertia effect between the low rotational speed range and the high rotational speed range is obtained. By closing the on-off valve 14 and opening the on-off 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, even compared to the conventional case where the intake passage was simply shortened to increase the inertia effect. .

The appropriate sizes of the intake expansion chamber 8 and the communication portion 13 to effectively exhibit the above-mentioned effects are as follows: The intake expansion chamber 8 has a capacity of 0.5 times or more the exhaust volume, and the communication portion 13 has a capacity that is 0.5 times or more the exhaust volume. It is desirable to keep the capacity 1.5 times or less. Furthermore, it is desirable that the capacity of the communicating portion 13 is smaller than that of the intake expansion chamber 8, and that the cross-sectional area of the communicating portion 13 is larger than the cross-sectional area of each independent intake passage 6.

In this case, the communication section 13 is arranged in parallel below the intake expansion chamber 8 by partitioning the tank section 17 into upper and lower sections with a partition plate 28.
Since it is formed by a part of the constituent wall (partition plate 28), the intake system that exhibits the above-mentioned functions and effects can be formed compactly and compactly, and its mountability on a vehicle can be improved. . In particular, as in the above embodiment, the tank section 17 that constitutes the intake expansion chamber 8 and the communication section 13 in the intake system structure 16, the integral intake pipe section 18 that constitutes the upstream portion 6a of each independent intake passage 6, and each independent intake A branch intake pipe section 19 and each branch hole 12 that constitute the downstream portion 6b of the passage 6
Each independent intake passage 6 is detoured around the tank part 17 by the communication pipe part 20 constituting the tank part 17, and is integrally formed using a part of the constituent wall of the tank part 17. Since each branch hole 12 is formed integrally with a part of the constituent wall of the tank section 17, it is necessary to obtain the required length of the independent intake passage 6 and the required volumes of the intake expansion chamber 8 and the communication section 13. As a result, these intake systems can be made more compact and smaller, and the required length and volume can be secured in a limited space (engine room), making it possible to install them in a vehicle. Further improvement can be achieved.

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 of the fuel injector 24.
It is necessary that the tank portion 17 of No. 6 be located therein, and that the on-off valve 14 be disposed in each of the branch holes 12. Therefore, the intake system structure 16 is located at a position below the center extension line of the tank portion 17, that is, on the side of the branch intake pipe portion 19, and the partition plate 28
At the position, the intake expansion chamber 8 is divided vertically into an upper divided body 16a and a lower divided body 16b by a dividing plane along the longitudinal direction, and both divided bodies 16a and 16b are connected to a partition plate 28.
Since the lower divided body 16b is connected via
is attached to the engine body 1 at its flange portion 21 by tightening bolts 22 from the side, and then the fuel injection valve 24 is inserted into the injection valve mounting hole 23 of each branch intake pipe portion 19 of the lower divided body 16b. Insert the fuel supply pipe 25 from the extension direction and connect it to the lower divided body 1.
6b to attach each fuel injection valve 24, and the on-off valve 14 is inserted from above into the branch hole 12 of each communication pipe portion 20 of the lower division body 16b and fixed to the valve shaft 15, Thereafter, the upper disassembled body 16a is joined to the lower divided body 16b with the partition plate 28 interposed therebetween, and both 16a and 16b are joined together by tightening the bolts 26 from below, thereby achieving a good result. Formability can be ensured, and upper and lower divided bodies 16a, 16b
Not only can the on-off valve 14 and the fuel injection valve 24 be easily assembled, but also 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 an advantage that a bulge can be formed, and a sufficient volume of the intake expansion chamber 8 can be secured.

Furthermore, when introducing EGR gas etc. into the intake expansion chamber 8, this EGR gas etc. is once introduced into the intake expansion chamber 8 into one large space and then supplied to each cylinder 4 via each independent intake passage 6. So, EGR
Gas, etc. can be distributed almost equally to each cylinder 4, and this good distribution property makes it possible to equalize the combustion state in each cylinder 4 and prevent torque fluctuations among each cylinder 4. In this case, a water drain hole 29 is provided in the partition plate 28 that partitions the intake expansion chamber 8 and the communication section 13, so that moisture contained in the EGR gas etc. introduced into the intake expansion chamber 8 can be removed. The water is drained through the drain hole 29 to the lower communication section 13 without accumulating, and from this communication section 13 is led to each cylinder 4 via each branch hole 12 for evaporation treatment. The above moisture is in the intake expansion chamber 8
Corrosion of the tank portion 17 due to accumulation in water can be prevented in advance and reliably. Also, at that time,
The water drain hole 29 is provided at a position corresponding to the intermediate point between the branch holes 12 and 12 so as not to face the on-off valve 14, so that water is drained from the intake expansion chamber 8 to the communication portion 13 through the water drain hole 29. The released moisture does not directly hit the on-off valve 14, and good operation of the on-off valve 14 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, it can be applied to an intake system in which a tank forming the intake expansion chamber 8 and a tank forming the communication section 13 are arranged vertically side by side, sharing a part of their outer walls; in this case, this partition If a drain hole is provided in the outer wall that is commonly used as a section, the same effects as in the above embodiment can be achieved.

Furthermore, the present invention is not limited to the case where the intake expansion chamber 8 and the communication section 13 are completely partitioned off as in the above embodiments, but the intake expansion chamber 8 and the communication section 13 are separated, for example, as shown by imaginary lines in FIG. Communication path 3 provided in the partition plate 28
The intake system further increases the filling efficiency of intake air by causing intake pressure vibration between the intake expansion chamber 8 and the communication part 13, which are communicated at 0 and communicated via the communication passage 30 in the low rotation range. It is also applicable to

Furthermore, the present invention is applicable not only to 4-cylinder engines as in the above embodiments, but also to other multi-cylinder engines, such as 5-cylinder engines.
It can also be applied to cylinder engines and six-cylinder engines. And the difference in the intake stroke of each cylinder is 4
In a cylinder engine, the angle is 180°, but in a 6-cylinder engine, for example, it is 120°. Therefore, when applying to a 6-cylinder engine, if the communication portion 13 is formed short, it is possible to connect a specific cylinder to another in the high rotation range. The pressure wave propagated from the cylinder through the communication section 13 and the reflected wave from the communication section 13 can be made to substantially match.

(Effects of the invention) As explained above, according to the invention, a communication portion is provided midway through which the mutually independent intake passages between the intake expansion chamber and each cylinder are communicated with each other,
Since the communication through the communication part is closed in the low engine speed range and opened in the high engine speed range, the inertia effect of the intake air can be enhanced in both the low and high speed ranges, especially in the high speed range. The pressure waves that propagate between the cylinders through the communication portion can further increase the intake air filling efficiency and significantly improve the output at high rotation speeds. Moreover, since the communication portions are arranged side by side on the lower side of the intake expansion chamber, the intake system that exhibits the above-mentioned effects can be formed small and compact, and it is possible to improve the ease of mounting on a vehicle.
Furthermore, since a drainage hole is provided in the partition that separates the intake expansion chamber and the communication section, when EGR gas, etc. is introduced into the intake expansion chamber to ensure good distribution, this EGR gas, etc. It is possible to prevent moisture contained in the intake air expansion chamber from accumulating in the intake air expansion chamber, thereby preventing corrosion of the constituent wall (tank) of the intake air expansion chamber.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the invention, FIG.
Vertical side view taken along the - line in the figure, Figure 2 is the 3rd
FIG. 3 is a longitudinal sectional side view taken along the line - in the figure, and FIG. 3 is a partially broken plan view. 1... Engine body, 4... Cylinder, 6... Independent intake passage, 8... Intake expansion chamber, 12... Branch hole,
13...Communication part, 14...Opening/closing valve, 17...Tank part, 28...Partition plate, 29...Drain hole.

Claims (1)

[Scope of Claim for Utility Model Registration] In an intake system for a multi-cylinder engine in which the upstream ends of independent intake passages provided independently for each cylinder are connected to intake enlargement chambers, the middle part of each independent intake passage is , is connected to a communication portion that branches upward from the middle of each of the independent intake passages and communicates each independent intake passage with each other, and the branch portion of the communication portion from each of the independent intake passages has a Opening/closing valves are installed that close the communication between the independent intake passage and the communication section in the low engine speed range and open it in the high engine speed range. By partitioning, the upper side of the partition part in the tank is formed as an intake expansion chamber, and the lower side is formed as a communication part, and the communication part is arranged in parallel with the lower side of the intake expansion chamber, and the communication part The volume of the intake air expansion chamber is set to be smaller than the volume of the intake air expansion chamber, and the partition section that separates the air intake expansion chamber from the communication section has a partition for draining moisture that has flowed into the intake air expansion chamber into the communication section. An intake system for a multi-cylinder engine characterized by being provided with a water drain hole.