JPS61197732A - Variable cylinder type internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knocking, by a method wherein, during full cylinder operation, air is fed to a first cylinder group, having a high compression ratio, at a low supercharge pressure, and to a second cylinder group, having a low compression ratio, at a high supercharge pressure. CONSTITUTION:When an electronic control part (ECU) 40 decides that full cylinder operation is needed, a valve lock mechanism 7 is released, and first and second superchargers 25 and 28 are actuated. A supercharge pressure produced by the first supercharger 25 is regulated through control of a first bypass valve 26. Meanwhile, a supercharge pressure by the second supercharger 28 is also regulated to a value higher than that of the first supercharger 25 through control of a second bypass valve 29. Air is fed to a first cylinder group A, having a compression ratio, at a low compression pressure and to a first cylinder group B, having a low compression ratio, at a high supercharge pressure. This prevents the occurrence of knocking during full cylinder operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a mechanical supercharger and performs so-called partial cylinder operation by suspending the operation of some cylinder groups depending on the operating state. It relates to a variable cylinder internal combustion engine.

[Conventional technology]

In an internal combustion engine configured to control engine load with a throttle valve, the fuel consumption rate worsens as the opening degree of the throttle valve decreases. In order to improve this fuel consumption rate, for example, variable cylinder internal combustion engines are known in which when the engine load is low, the operation of some cylinder groups is stopped and the remaining cylinder groups are operated at high load. ing. Now, in such an internal combustion engine, the compression ratio of the cylinder that operates only in the full load range is set lower than the compression ratio of the cylinder that operates constantly in order to prevent the occurrence of non-king, and the compression ratio of the cylinder that operates only in the full load range is set lower than that of the cylinder that operates only in the full load range. A configuration in which a supercharger is installed in the intake system has been proposed (Japanese Patent Application Laid-Open No. 1983-1999)
-110532).

[Problem that the invention seeks to solve]

In order to further improve the output of the conventional device described above, if a supercharger is installed in the intake system of the cylinder that is constantly in operation,
There is a problem that knocking occurs and abnormal combustion occurs.

[Means for solving problems]

In order to solve the above problems, the variable cylinder internal combustion engine according to the present invention has a first cylinder group that is always in operation, a second cylinder group that is inactive depending on the operating state, and high-pressure air is supplied to both cylinder groups. The compression ratio of each cylinder in the second cylinder group is set lower than the compression ratio of each cylinder in the first cylinder group, and the supercharger During operation, air is supplied to the second cylinder group at a higher supercharging pressure than to the first cylinder group.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a first embodiment of the present invention, in which cylinders 1°2.3.
4.5.6 is divided into a first cylinder group A that is always in operation and a second cylinder group B that is inactive when the engine output is low. The compression ratios of cylinders 1 and 2.3 of the first cylinder group A are relatively large;
The compression ratio of cylinder 4°5.6 in cylinder group B is set relatively small. A pulp lock mechanism 7 is provided above each intake valve of the second cylinder group B to stop the operation of these intake valves. The intake passage 20 branches midway into a first auxiliary passage 21 and a second auxiliary passage 22, and a surge tank 23 formed at the tip of the first auxiliary passage 21 is connected to the cylinder 1. 2.
3, and the surge tank 24 formed at the tip of the second sub passage 22 is provided with three branch pipes that communicate with the cylinders 4, 5, and 6, respectively. It will be done.

A first supercharger 25 made of a roots pump is provided in the middle of the first auxiliary passage 21, and the inlet side and outlet side of the first supercharger 25 are connected to a first bypass passage 27 having a first bypass valve 26. Connected by Further, a second supercharger 28 made of a roots pump is provided in the middle of the second auxiliary passage 22, and like the first supercharger 25, this second supercharger 28 also has a second bypass valve 29. A two-bypass passage 30 connects the end side and the outlet side. The electromagnetic clutch pulley 33 of the first supercharger 25 is connected to the crank pulley 35 via an endless belt 34, and the electromagnetic clutch pulley 36 of the second supercharger 28 is connected to the crank pulley 35 via an endless belt 37. 1 is connected to the pulley 33 of the supercharger 25. Therefore, the first supercharger 25 is driven via the crankboo 1J35, the belt 34, and the pulley 33, and the second supercharger 28 is driven via the pulley 33, the belt 37, and the pulley 36. First, a pressure sensor 31 is provided in the surge tank 23 to measure the supercharging pressure of the supercharging machine 25.
Similarly, in order to measure the supercharging pressure of the second supercharger 28,
A pressure sensor 32 is also provided in the surge tank 24.

An air cleaner 10 is provided at the inlet of the intake passage 20, and this air, the cleaner 1. ．． 0 and the branch part of the intake passage 20, an air flow meter 11 for measuring the amount of intake air and a throttle valve 12 for regulating the amount of air are provided.
and will be provided. Note that the rotation speed detector 13 is attached to a de-estrivator (not shown).

Electronic control unit (ECU) 4 equipped with a microcomputer
0 is no air flow. Based on the input signals from the engine 11, the rotation speed detector 13, the pressure sensors 31, 32, etc.
Palpro-tsuk mechanism 7, first and second supercharger 25.2
8 electromagnetic clutch, first and second bypass valves 26.2
Controls 9th grade.

FIG. 2 is a flowchart showing the control of the ECU 40. In step 101, it is determined whether the value Q/N obtained by dividing the intake air amount Q by the engine rotation number N is 0.3 or less. Q
/N corresponds to the size of the load, and Q/N≦
If it is 0.3, it is a light load operation state, so step 10
2, the valve lock mechanism 7 is operated to bring the second cylinder group B to rest in order to perform partial cylinder operation. Also step 1
03, and if the superchargers 25 and 28 were operating before then, they are stopped.

If Q/N is greater than 0.3 in step 101, it is determined in step 104 whether Q/N is 0.5 or less. If 0.3<Q/N≦0.5, the load is slightly larger than in the above case, and the process moves to step 105.
The valve lock mechanism 7 is operated to perform partial cylinder operation. Then, in step 106, the first supercharger 25 is activated.
Connect the electromagnetic clutch of Pooh 1J33 to operate it.

If Q/N is greater than 0.5 in step 104, the process moves to step 107, where it is determined whether Q/N is 0.7 or less. If 0.5<Q/N≦0.7, it is a high-load operating state, and step 108 is executed to release the valve lock mechanism 7 to operate all cylinders, and then in step 109, the supercharger 25. 28 is stopped.

If Q/N>0.7 in step 107, the engine is being operated at a higher load than in the case of executing steps 108 and 109, and in step 110 the valve lock mechanism 7 is released in order to operate all cylinders. With,
In step 111 the first and second superchargers 25.2
Activate 8. Next, in step 112, the supercharging pressure P+ by the first supercharger 25 detected by the pressure sensor 31
is larger than 400fiHg. If the boost pressure P+ is greater than 400flHg, step 11
3 to open the first bypass valve 26 and increase the supercharging pressure P1.
prevent it from rising any higher. Conversely, if the boost pressure P is 400 mHg or less, step 114 is executed,
The first bypass valve 26 is closed to allow the boost pressure to increase. In step 115, it is determined whether the supercharging pressure P2 from the second supercharger 28 detected by the pressure sensor 32 is greater than 500 nHg. If the supercharging pressure P2 is greater than 500 mHg, step 116 is executed to open the second bypass valve 29 and limit the increase in the supercharging pressure P2. Conversely, if the supercharging pressure P is smaller than 500 mHg, step 117 is executed to close the second bypass valve 29, thereby allowing the supercharging pressure P2 to rise. In this way, the second supercharger 28 can supply air at a higher boost pressure than the first supercharger 25.

As described above, in this embodiment, during all-cylinder operation, air is supplied at a relatively low boost pressure to the first cylinder group A, which has a high compression ratio, and to the second cylinder group B, which has a low compression ratio. In contrast, air is supplied at a relatively high boost pressure. Therefore, during all-cylinder operation, good combustion can be achieved without knocking, and output can be improved.

FIG. 3 shows a second embodiment. This second embodiment is different from the first embodiment by changing the ratio of the diameters of the pulley 33 of the first supercharger 25 and the pulley 36 of the second supercharger 28. Changing the discharge pressure. That is, the diameter of the pulley 33 is set larger than the diameter of the pulley 36, thereby increasing the rotational speed of the second supercharger 28 than that of the first supercharger 25 and increasing the discharge capacity. Note that the other configurations are the same as in the first embodiment.

Furthermore, since the supercharger 25.degree. 28 is not provided with a bypass passage and a bypass valve, the control performed by the ECU 40 is performed in steps 101 to 111 in FIG.
12 to 117 are unnecessary.

FIG. 4 shows a third embodiment. In this embodiment, the housing of the second supercharger 28 is molded larger than the housing of the first supercharger 25, thereby increasing the theoretical discharge amount of the second supercharger 29 from that of the first supercharger 25. It is thicker than that (Fig. 5(a)).

(As shown in bl, assuming that the diameter of the housing is 01 and the width is L, the theoretical discharge amount Q is expressed as α·D2·L, where α is a coefficient.

The control of the ECU 40 in this embodiment is the same as in the second embodiment, from steps 101 to 111 in FIG.

FIG. 6 shows a fourth embodiment. In this fourth embodiment, there is only one supercharger 25, and first and second sub passages 21, 22 are provided on the discharge side of this supercharger 25. Check valves 51.52 are provided in the middle of the first and second sub-paths 21.22, respectively, to prevent backflow of air. The other configurations are the same as in the first embodiment.

Control of the ECU 40 is similar to that of the first embodiment.

That is, based on the pressure detected by the pressure sensor 31, the first
The bypass valve 26 is opened and closed, and the second bypass valve 29 is opened and closed based on the pressure detected by the pressure sensor 32. Therefore, the air pressure supplied via the second sub-passage 22 is higher than the air pressure supplied via the first sub-passage 21.

Therefore, the control performed in this embodiment is basically the same as the flowchart shown in FIG.

It goes without saying that the superchargers 25 and 29 are not limited to Roots pumps.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain the effect that the output can be improved without causing non-king during all-cylinder operation.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing the first embodiment of the present invention, Fig. 2 is a flowchart showing control of the electronic control section, Fig. 3 is a system diagram showing the second embodiment, and Fig. 4 is the third embodiment. A family tree showing
FIG. 5(a) is a horizontal sectional view showing the housing of the supercharger;
5-) are sectional views taken along the line B--B in FIG. 5(a), and FIG. 6 is a system diagram showing the fourth embodiment. 25.28...Supercharger, A...1st cylinder group, B...2nd cylinder group. Figure 1 Figure 3 [1i Chestnut 4 (l Figure 5 (a) (b) !, -s Figure 6

Claims (1)

[Claims] 1. It includes a first cylinder group that is always in operation, a second cylinder group that is stopped depending on the operating state, and a supercharger that supplies high-pressure air to both cylinder groups, and the compression ratio of each cylinder in the second cylinder group is is set lower than the compression ratio of each cylinder in the first cylinder group, and the supercharger applies a higher supercharging pressure to the second cylinder group than to the first cylinder group when both cylinder groups are in operation. A variable cylinder internal combustion engine that is characterized by supplying air.