JPH09151737A - Intake device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain increase of intake efficiency, reduction of a pumping loss, etc., in an internal combustion engine of Atkinson cycle. SOLUTION: As a combustion cycle of an engine 1, an Atkinson cycle of delay closing type of intake valves 8 to 11 is applied. Check valves L1 to L4 opened at suction stroke time and closed at compression stroke time are provided in each independent intake pipe 4 to 7. In accordance with a firing order of each cylinder #1 to #4, a connection pipe (for instance, 16) is provided which connects the independent intake pipe (for instance, 4) of a certain cylinder (for instance, #1) and the independent intake pipe (for instance 6) of a cylinder (for instance, #3) in the next ignition timing, and each connection pipe 16 to 19 is provided with supercharging check valves s1 to s4. The supercharging check valves s1 to s4 are closed at suction stroke time of a piston in a certain cylinder #1, #3, #4, #2, regulate a reverse flow of intake air from the cylinder #3, #4, #2, #1, in the next ignition timing, are opened at compression stroke time, and positively permit an inflow of intake air to the cylinder #3, #4, #2, #1, in the next to the ignition timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an internal combustion engine, and more particularly to an intake device for an internal combustion engine that employs a so-called Atkinson cycle.

[0002]

2. Description of the Related Art Generally, a piston of an internal combustion engine moves up and down in a cylinder (cylinder bore), and the behavior in the cylinder is expressed by a series of cycles of intake, compression, combustion, expansion and exhaust. As a conventionally known combustion cycle, what is called an Otto cycle can be mentioned. In this Otto cycle, the relationship between the volume (v) in the cylinder bore and the pressure (p) in the cylinder bore is as a pv diagram (however, this diagram is only a schematic one) as shown in FIG. Can be represented. This Otto cycle is characterized in that the expansion ratio and the compression ratio have a substantially equal relationship.

In such an Otto cycle, in order to increase the thermal efficiency, it is conceivable to increase the compression ratio (≈expansion ratio), but simply increasing the compression ratio causes a problem of knocking. Therefore, there is a limit to simply increasing the compression ratio.

For the Otto cycle having the above-mentioned drawbacks, for example, SAE Technical Paper
A series called Atkinson cycle (also called Miller cycle in some cases) is disclosed in Series No. 910451 and the like. In this Atkinson cycle, the actual compression ratio is lowered by increasing the expansion ratio and then changing the closing timing of the intake valve. Normally, the actual compression ratio is lowered by delaying the closing timing of the intake valve after the intake bottom dead center (of course, the actual compression ratio is lowered even in the case of early closing). In the late closing type Atkinson cycle, the relationship between the volume (v) in the cylinder bore and the pressure (p) in the cylinder bore is, for example, p-v as shown in FIG.
It can be represented as a diagram (however, the diagram is also a schematic one).

[0005]

However, in the above-mentioned conventional technique, particularly in the late-closing type Atkinson cycle, the closing timing of the intake valve is delayed, so that the intake air is blown back. For this reason, the intake air temperature rises, and the density of the intake air is reduced. Therefore, the low-density air is repeatedly taken into another cylinder bore, which eventually reduces the intake air amount of the internal combustion engine as a whole. As a result, the intake efficiency may decrease and the pumping loss may increase.

Further, due to the blowback of the intake air, the pulsation in the intake pipe increases, and even with such a large pulsation, the intake air amount decreases, which may lead to the above-mentioned problems. Furthermore, since the intake air temperature rises, there is a risk that the thermal reliability of various parts in the intake passage (for example, the throttle body, the intake pipe, etc.) may decrease.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to increase the intake efficiency and reduce pumping loss in an internal combustion engine employing the Atkinson cycle, and to improve the intake passage. An object of the present invention is to provide an intake device for an internal combustion engine, which can suppress adverse thermal effects on various components inside.

[0008]

In order to achieve the above object, in the invention described in claim 1, there are provided a plurality of cylinders each having a piston therein, and an independent intake pipe leading to each cylinder is connected. In addition, the intake valve is closed later than the intake bottom dead center of the piston, so that the expansion ratio is set to be larger than the actual compression ratio.
Each of the independent intake pipes is provided with a check valve that is opened during the intake stroke of the piston corresponding to itself and closed to restrict the reverse flow of intake air to the upstream side during the compression stroke of the piston corresponding to itself. That is the point.

According to the above arrangement, the intake valve is closed later than the intake bottom dead center of the piston, so that the expansion ratio becomes larger than the actual compression ratio and the thermal efficiency can be increased. Since the intake valve is closed later than the intake bottom dead center of the piston in this manner, the intake air drawn into the polygonal cylinder may be blown back during the compression stroke of the piston. However, in the present invention, each independent intake pipe is provided with a check valve. Since this check valve is opened during the intake stroke of the piston, there is no obstacle to the intake. Further, the piston is closed during the compression stroke, so that the backflow of the intake air due to the blowback to the upstream side is restricted. Therefore, the intake air temperature is prevented from rising, and the intake air density is also prevented from decreasing due to the intake air temperature rising. Furthermore, it is possible to prevent the pulsation in the intake pipe from increasing due to the backflow of intake air to the upstream side.

Further, according to the invention described in claim 2, in the intake system for an internal combustion engine according to claim 1, the independent intake pipe corresponding to a certain cylinder and the ignition timing are next in accordance with the ignition order of each cylinder. A connecting pipe that communicates with an independent intake pipe corresponding to the corresponding cylinder is provided, and in the connecting pipe, during the intake stroke of the piston in the certain cylinder, the reverse intake of the intake air from the cylinder having the next ignition timing is regulated. However, the gist of the invention is to provide a check valve for supercharging that allows the intake air to flow into the cylinder whose ignition timing is next during the compression stroke of the piston in the certain cylinder.

According to the above construction, in addition to the operation of the invention described in claim 1, according to the ignition sequence of each cylinder,
The connection pipe connects the independent intake pipe corresponding to a certain cylinder and the independent intake pipe corresponding to the cylinder whose ignition timing is next. Further, a check valve for supercharging is provided in the connection pipe. Therefore, during the intake stroke of the piston in the certain cylinder, the check valve for supercharging is closed, and the reverse flow of intake air from the cylinder whose ignition timing is next is restricted. Further, during the compression stroke of the piston in the certain cylinder, the check valve for supercharging is opened, and the inflow of intake air to the cylinder having the next ignition timing is permitted. Therefore, at this time, if the cylinder with the next ignition timing is in the intake stroke, in addition to the intake air that is taken in through the independent intake pipe, the intake air that is blown back from the certain cylinder is excessive. Since it is introduced as a supply, the intake air amount can be increased overall.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which an intake system for an internal combustion engine according to the present invention is applied to a gasoline engine will be described in detail below with reference to the drawings.

FIG. 1 is a schematic configuration diagram schematically showing an intake device of an engine 1 as an internal combustion engine mounted on a vehicle in the present embodiment. As shown in the figure, the engine 1 includes a plurality of (four in the present embodiment) cylinders # 1, #.
2, # 3 and # 4, a piston (not shown) is reciprocally disposed in each of the cylinders # 1 to # 4. In each of the cylinders # 1 to # 4, an air cleaner (not shown) passes through a plurality of independent intake passages 4, 5, 6, 7 constituted by the main intake passage 2 and the intake manifold 3,
The outside air (intake air) is introduced.

Further, at the same time when the outside air is taken into the cylinders # 1 to # 4, fuel injected from an injector (not shown) near the intake port in each of the independent intake passages 4 to 7 is also introduced. It has become. Then, the introduced air-fuel mixture of the fuel and the outside air is introduced into the combustion chamber via the intake valves 8, 9, 10, 11 provided for each of the cylinders # 1 to # 4. Exploding and burning in the combustion chamber to obtain the driving force. Further, the exhaust gas after the explosion and combustion passes from the combustion chamber through the exhaust valve 12 through the exhaust manifold 13 for each cylinder, is guided to the exhaust passage 14, and is finally discharged to the outside. .

In the middle of the main intake passage 2, a throttle valve 15 opened and closed by the operation of an accelerator pedal (not shown).
Is provided. When the throttle valve 15 is opened and closed, the main intake passage 2 and thus each cylinder #
The amount of intake air into 1 to # 4 is adjusted. A surge tank (not shown) that smoothes the pulsation of intake air is provided downstream of the throttle valve 15.

Next, a characteristic part of this embodiment will be described. First, in the present embodiment, a so-called Atkinson cycle is adopted as the combustion cycle of the engine 1. In this Atkinson cycle, the expansion ratio is set to be larger than that of the normal Otto cycle (the stroke amount of the piston is large), and the closing timing of the intake valves 8 to 11 is later than usual (the intake stroke of the piston is below). It is set later than the dead point). Thus, the actual compression ratio is lowered by delaying the closing timing of the intake valves 8 to 11. In the present embodiment, for example, the expansion ratio is “15” and the actual compression ratio is “1”.
It is set to "0".

Further, as shown in FIG. 1, check valves L1, L2, L3, L4 are provided in each of the independent intake pipes 4-7. These check valves L1 to L4 are configured by so-called reed valves, and are opened during the intake stroke of the piston corresponding to the check valve L1 to L4 and closed during the compression stroke of the piston. Therefore, the intake air once introduced to the downstream side of the check valves L1 to L4 is
Basically, it does not flow back to the upstream side of the check valves L1 to L4.

Further, in the present embodiment, the ignition order of each cylinder # 1 to # 4 is set in the order of # 1 → # 3 → # 4 → # 2. Then, according to the ignition order, an independent intake pipe (for example, reference numeral 4) corresponding to a certain cylinder (for example, # 1) and a cylinder whose ignition timing is next (for example, # 3)
A connection pipe (for example, reference numeral 16) that communicates with the independent intake pipe (for example, reference numeral 6) corresponding to is provided. Therefore, in the present embodiment, the four connecting pipes 16, 17, 18, 19
Therefore, the connecting pipe 16 includes the independent intake pipe 4 corresponding to the cylinder # 1 and the independent intake pipe 6 corresponding to the cylinder # 3.
The connecting pipe 17 connects the independent intake pipe 6 corresponding to the cylinder # 3 and the independent intake pipe 7 corresponding to the cylinder # 4. Further, the connecting pipe 18 connects the independent intake pipe 7 corresponding to the cylinder # 4 and the independent intake pipe 5 corresponding to the cylinder # 2, and the connecting pipe 19 is connected to the independent intake pipe 5 corresponding to the cylinder # 2 and the cylinder. #
It communicates with the independent intake pipe 4 corresponding to 1.

In addition, supercharging check valves s1, s2, s3, s4 are provided on one end side of each of the connecting pipes 16 to 19 (on the side of the independent intake pipe corresponding to the cylinder whose ignition timing is next). Has been. These supercharging check valves s1 to s4 are also configured by so-called reed valves. Then, these check valves s1 to s4 for supercharging are provided in certain cylinders # 1, # 3, #.
During the intake stroke of the pistons in the cylinders # 4 and # 2, the ignition timing is closed to restrict the reverse flow of intake air from the cylinders # 3, # 4, # 2 and # 1, which are the next cylinders, and the cylinders # 1 and # 3. , ♯
During the compression stroke of the pistons in # 4 and # 2, the ignition timing is opened to allow the inflow of intake air into the cylinders # 3, # 4, # 2 and # 1 which are the next cylinders. For example, the check valve s1 for supercharging provided in the connection pipe 16 is closed during the intake stroke of the piston in the cylinder # 1, and restricts the reverse intake of the intake air from the cylinder # 3, which has the next ignition timing. . Further, the check valve s1 for supercharging is opened during the compression stroke of the piston in the cylinder # 1 so as to allow the intake air to flow into the cylinder # 3, which is the next ignition timing.

In addition, in the present embodiment, when the combustion cycle in a certain cylinder (eg, # 1) is in the compression stroke, the combustion cycle in the cylinder (eg, # 3) with the next ignition timing is the intake stroke. Is set to.

Next, the operation and effect of this embodiment configured as described above will be described. (1) In the present embodiment, since the Atkinson cycle is adopted as described above, that is, the intake valves 8 to
Since the closing timing of 11 is set to be later than usual (later than the intake bottom dead center of the piston), the actual compression ratio is lowered. Therefore, the expansion ratio becomes larger than the actual compression ratio, and the thermal efficiency can be increased.

(2) Now, since the intake valves 8 to 11 are closed later than the intake bottom dead center of the piston,
The intake air drawn into the break-angle cylinders # 1 to # 4 may be blown back during the compression stroke of each piston. However, in the present embodiment, the check valves L1 to L4 are provided in the individual independent intake pipes 4 to 7, respectively. These check valves L1
As shown in FIG. 3 to FIG. 6, since each of L4 to L4 is opened during the suction stroke of the piston, no problem occurs in the suction. Further, as shown in FIGS. 3 to 6, the check valves L1 to L4 are closed during the compression stroke of the piston. (For example, as shown in FIG. 3, cylinder # 1
In the compression stroke of the piston, the check valve L1 is closed. By this, the backflow of the intake air due to the blowback to the upstream side is restricted. Therefore, the intake air temperature is prevented from rising, and the intake air density is also prevented from decreasing due to the intake air temperature rising.

(2-1) Therefore, it is possible to prevent the intake air amount of the engine 1 as a whole from decreasing due to repeated intake of low-density intake air into the cylinders # 1 to # 4. it can. As a result, it is possible to increase intake efficiency and reduce pumping loss.

(2-2) Further, since the backflow of the intake air to the upstream side can be suppressed, it is possible to prevent the pulsation in the main intake passage 2 from increasing. Therefore, it is possible to suppress a decrease in the intake air amount due to an increase in pulsation, and it is possible to further ensure the above-described operational effects.

(2-3) Furthermore, since the rise in intake air temperature can be suppressed, it is possible to prevent the thermal reliability of the main intake passage 2 and various internal parts (such as the throttle valve 15) from deteriorating. can do.

(3) In addition, in the present embodiment, the cylinders # 1, # 3, # 4, and # 2 correspond to the cylinders # 1, # 3, # 4, and # 2 in the ignition order. Independent intake pipes 4, 6, 7, 5 and cylinder # with ignition timing next
3, # 4, # 2, # 1 independent intake pipes 6, 7,
The connecting pipes 16 to 19 communicate with the pipes 5 and 4. Further, the check valves s for supercharging are provided in the connection pipes 8 to 11.
1 to s4 are provided.

Therefore, for example, as shown in FIG. 3, during the compression stroke of the piston in the cylinder # 1, the check valve s1 for supercharging of the connecting pipe 16 is opened and the ignition timing comes next in the cylinder # 3. Inflow of intake air into the air is allowed. At this time,
The piston in the cylinder # 3 is in the intake stroke, and in addition to the intake air that is taken in through the independent intake pipe 6, the blowback intake air from the cylinder # 1 is supercharged into the cylinder # 3. As a result, the intake air amount can be increased overall.

Further, during the intake stroke of the piston in the cylinder # 1, as shown in FIG. 6, the check valve s for supercharging the connecting pipe 16 is shown.
Cylinder # 3, in which No. 1 is closed and the ignition timing is next
The reverse flow of intake air from is regulated.

Similarly, for example, as shown in FIG. 4, during the compression stroke of the piston in the cylinder # 3, the supercharging check valve s2 of the connecting pipe 17 is opened, and the ignition timing comes next in the cylinder # 4. Inflow of intake air into the air is allowed. At this time, the piston in the cylinder # 4 is in the intake stroke, and in addition to the intake air taken through the independent intake pipe 7,
The intake air blown back from inside 3 is supercharged into cylinder # 4, and the intake air amount can be increased overall. Further, during the intake stroke of the piston in the cylinder # 3, as shown in FIG. 3, the check valve s2 for supercharging the connecting pipe 17 is shown.
Is closed, and the reverse flow of intake air from cylinder # 4, which is the next ignition timing, is restricted.

Similarly, for example, as shown in FIG. 5, during the compression stroke of the piston in the cylinder # 4, the check valve s3 for supercharging of the connecting pipe 18 is opened, and the ignition timing is transferred to the cylinder # 2. Inflow of intake air is allowed. Further, at this time, the piston in the cylinder # 2 is in the intake stroke, and in addition to the intake air sucked through the independent intake pipe 5,
The intake air blown back from inside 4 is supercharged into cylinder # 2, and the intake air amount can be increased overall. Further, during the intake stroke of the piston in the cylinder # 4, as shown in FIG. 4, the check valve s3 for supercharging the connecting pipe 18
Is closed, and the reverse injection of intake air from cylinder # 2 with the next ignition timing is restricted.

Further, similarly, for example, as shown in FIG. 6, during the compression stroke of the piston in the cylinder # 2, the connecting pipe 1
The check valve s4 for supercharging No. 9 is opened, and the intake air is allowed to flow into the cylinder # 1 whose ignition timing is next. At this time, the piston in cylinder # 1 is in the intake stroke,
In addition to the intake air that is taken in through the independent intake pipe 4, the intake air that is blown back from the cylinder # 2 will be supercharged into the cylinder # 1. Can be increased. Further, during the intake stroke of the piston in the cylinder # 2, as shown in FIG. 5, the supercharging check valve s4 of the connecting pipe 19 is closed, and the intake timing from the cylinder # 1 whose ignition timing is next is reversed. Entry is restricted.

As described above, in the present embodiment, the connecting pipe 1
6 to 19 communicate with each other, and further, check valves s1 to s4 for supercharging are provided in the connection pipes 8 to 11. Therefore, certain cylinders # 1 and # in the compression stroke
For the cylinders # 3, # 4, # 2, and # 1 in which the ignition timing is next to that of # 3, # 4, # 2, and the intake stroke, the intake air passes through the independent intake pipes 4, 5, 6, and 7. In addition to the intake air that is inhaled as described above, the cylinders # 1, # 3, # 4,
The blow-back intake air from inside # 2 is supercharged. Therefore, the intake air amount can be increased overall. As a result, it is possible to increase the intake air amount of the engine 1 as a whole, and further increase the intake efficiency and reduce the pumping loss.

In addition to this, the above (2-2),
The effect of (2-3) can be made more reliable.
The present invention is not limited to the above embodiment, and may be configured as follows, for example.

(1) In the above-described embodiment, the check valves L1 to L1.
The L4 and the supercharging check valves s1 to s4 are reed valve type valves, but other check valves (for example, type valves that are opened and closed by an actuator such as a motor) are used. May be.

(2) In the above embodiment, the present invention is embodied in the intake system of the gasoline engine 1, but it may be embodied in the intake system of the diesel engine. (3) In the above-described embodiment, the engine 1 having four cylinders # 1 to # 4 is embodied, but the number of cylinders is not limited at all, and, for example, in the case of 6 cylinders and 8 cylinders as well. Can be converted. Also, the ignition order is not limited to the order described in the above embodiment.

(4) Connection pipe 16 in the above embodiment
To 19 and the supercharging check valves s1 to s4 may be omitted. A technical idea which is not described in each claim of the claims and can be grasped from the above-described embodiment will be described below together with its effect.

(A) In the intake system for an internal combustion engine as set forth in claim 2, when the combustion cycle in the certain cylinder is in the compression stroke, the combustion cycle in the cylinder whose ignition timing is next is the intake stroke. It is characterized in that it is configured.

With the above-mentioned structure, during the compression stroke of the piston in a certain cylinder, the intake air is positively and supercharged to the cylinder whose ignition timing is the next, which is more reliable. It is possible to increase intake efficiency and reduce pumping loss.

[0039]

As described in detail above, according to the present invention,
In an internal combustion engine that employs the Atkinson cycle, it is possible to increase intake efficiency and reduce pumping loss, and it is possible to suppress thermal adverse effects on various components in the intake passage.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an intake device for an engine according to an embodiment.

FIG. 2 p-v for explaining the Atkinson cycle
FIG.

FIG. 3 is a schematic diagram of an engine for explaining the operation of the embodiment.

FIG. 4 is a schematic diagram of an engine for explaining the operation of the embodiment.

FIG. 5 is a schematic diagram of an engine for explaining the operation of the embodiment.

FIG. 6 is a schematic diagram of an engine for explaining the operation of the embodiment.

FIG. 7 p-v illustrating the Otto cycle of the prior art
FIG.

[Explanation of symbols]

1 ... Engine as internal combustion engine, 2 ... Main intake passage, 4,
5, 6, 7 ... Independent intake pipe, 8, 9, 10, 11 ... Intake valve, 16, 17, 18, 19 ... Connection pipe, # 1, # 2, #
3, # 4 ... Cylinder, L1, L2, L3, L4 ... Check valve, s
1, s2, s3, s4 ... Check valve for supercharging.

Claims (2)

[Claims] 1. A plurality of cylinders each having a piston inside, and an independent intake pipe leading to each cylinder is connected,
In the internal combustion engine in which the expansion ratio is set to be larger than the actual compression ratio by closing the intake valve later than the intake bottom dead center of the piston, each of the independent intake pipes has a piston corresponding to itself. An intake device for an internal combustion engine, comprising a check valve which is opened during an intake stroke and is closed to restrict a reverse flow of intake air to an upstream side during a compression stroke of a piston corresponding to the piston. 2. The intake system for an internal combustion engine according to claim 1, wherein an independent intake pipe corresponding to a certain cylinder and an independent intake pipe corresponding to a cylinder whose ignition timing is next are provided according to the ignition order of each cylinder. While providing a connection pipe that communicates with each other, in the connection pipe, during the intake stroke of the piston in the certain cylinder, the ignition timing controls the reverse entry of intake air from the cylinder that is next, and the piston in the certain cylinder An intake system for an internal combustion engine, comprising: a check valve for supercharging, which allows intake air to flow into a cylinder whose ignition timing is next during a compression stroke.