JPS6230287B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cylinder-deactivated engine in which the number of activated cylinders can be controlled by shifting some of the cylinders to a cylinder-deactivation state during operation. In conventional cylinder-deactivated engines of this type, for example, during low-load operation, in order to increase combustion efficiency and prevent the generation of harmful gases, or increase the load factor to reduce pumping loss and improve fuel efficiency, The engine is operated with some of its cylinders in a cylinder deactivated state. By the way, in such a cylinder-deactivated engine, the first
As shown in the figure, the output PS1 when all cylinders are operated and the output PS2 when some cylinders are operated when the opening degree of the throttle valve is changed at a given constant engine speed.
There is a point P (hereinafter referred to as a "cross point") at which the two are the same at the same throttle valve opening. Therefore, by switching from full-cylinder operation to partial-cylinder operation or vice versa at such a cross point P, a shock at the time of switching can be prevented. However, in conventional cylinder-deactivated engines, the cross point P is closer to the low load side, so the region in which partial cylinder operation can be performed is narrow, and there is a natural limit to improving fuel efficiency. Therefore, in order to improve fuel efficiency, if the switching point Q is moved to the high load side as shown in Fig. 1, the output difference △PS between all-cylinder operation and some cylinder operation becomes large. There is a problem that the shock during switching becomes large. The present invention aims to solve these problems by adjusting the cross point so that it can shift to the high load side, thereby eliminating shock during switching and improving fuel efficiency by creating a deactivated engine. The purpose is to provide. For this reason, the present invention provides an exhaust gas recirculation system that recirculates exhaust gas from the exhaust system to the intake system in an engine that can control the number of operating cylinders to perform full cylinder operation or partial cylinder operation, and an exhaust gas recirculation system that recirculates exhaust gas from the exhaust system to the intake system. Equipped with an air-fuel ratio changing system that can change the air-fuel ratio of the air-fuel mixture, the point (cross point) where the output during all-cylinder operation and the output during partial-cylinder operation are the same at the same throttle valve opening. The present invention is characterized in that cross-point control means is provided to control the amount of exhaust gas recirculation in the exhaust gas recirculation system and to control the air-fuel ratio changing system according to the operating state in order to adjust the exhaust gas recirculation system. Hereinafter, a cylinder deactivation engine as an embodiment of the present invention will be explained with reference to the drawings. Fig. 2 is a schematic diagram for explaining its general configuration, and Figs. 3 and 4 are graphs for explaining its operation. 5th and 6th
Each figure is a graph for explaining the effects of the modified examples. Now, this engine has two cylinders for cylinder deactivation (in this case, cylinders 1 and 4) that can stop operating and shift to a cylinder deactivation state depending on the operating state (for example, low-load operating state), and the above cylinders. By having two regular cylinders (in this case, the 2nd and 3rd cylinders) that are always activated regardless of the operating state, the number of activated cylinders can be controlled to allow 4-cylinder operation (all-cylinder operation) or 2-cylinder operation. It is configured as an in-line four-cylinder engine with cylinders deactivated (partial cylinder operation). Also, an exhaust gas recirculation passage (hereinafter referred to as "EGR passage") 3 that can recirculate exhaust gas from the exhaust passage (exhaust system) to a portion of the intake passage (intake system) 1 downstream of the part where the throttle valve 2 is disposed. is provided. Furthermore, an air bleed type metering device 5 for the carburetor 4 constituting the air-fuel ratio changing system A is provided. , the ratio of the amount of fuel from the carburetor 4 can be changed (specifically, reduced), and thereby the air-fuel ratio of the air-fuel mixture flowing through the intake passage 1 can be changed. By the way, cross-point control means C is provided to control the amount of exhaust gas recirculation (hereinafter referred to as "EGR amount") in the EGR passage 3 constituting the exhaust gas recirculation system B, and to control the amount of bleed air in the air-fuel ratio changing system A. ing. This cross point control means C will be specifically explained below. First, in the EGR passage 3, a first EGR control valve 7 and a second EGR control valve 8 are provided in parallel with each other, and each EGR control valve 7, 8 is configured as a differential pressure responsive diaphragm motor. The first EGR control valve 7 includes chambers 7c and 7d separated by a diaphragm 7b with a valve body 7a, and a spring 7e is loaded in the chamber 7c. Further, the second EGR control valve 8 includes 8c and 8d partitioned by a diaphragm 8b with a valve body 8a, and a spring 8e is loaded in the chamber 8c. One end of a control passage 9 is connected to the chamber 7c of the first EGR control valve 7, and one end of a control passage 10 is connected to the chamber 8c of the second EGR control valve 8. The other end of each control passage 9, 10 opens into the intake passage 1, and its opening position is on the upstream side of the throttle valve when the throttle valve 2 opens at a predetermined opening or less, and when the throttle valve 2 opens at a predetermined opening or more. It is set at a position downstream of the throttle valve. Note that the pressure inside the chambers 7d and 8d is adjusted to atmospheric pressure. A third EGR control valve 11 is interposed in the EGR passage 3, and this third EGR control valve 11 operates in conjunction with the throttle valve 2, and the third EGR control valve 11 operates in conjunction with the throttle valve 2.
This assists the control of the EGR amount by the control valves 7 and 8. Further, a vacuum control unit (hereinafter referred to as "VCU") 12 is provided, and this VCU 12 is turned on (valve) on the high-speed side of the part D shown in FIG. It is configured as a control mechanism that turns off (closes the valve) on the low speed side. That is,
This VCU 12 has chambers 12c and 12d separated by a diaphragm 12b with a valve body 12a, and a spring 12e inside the chamber 12c.
is loaded. Further, one end of a control passage 14 is connected to the chamber 12c via an operation delay orifice 13 of the VCU 12, and the other end of this control passage 14 is connected to the opening position of the control passages 9 and 10 described above. It is open in position. That is, the control passage 14 is also configured to open upstream of the throttle valve 2 when the opening degree is less than a predetermined opening degree, and to open downstream of the throttle valve 2 when the opening degree of the throttle valve 2 is more than a predetermined opening degree. Although the opening positions of the control passages 9, 10, and 14 are schematically illustrated in an exaggerated manner in FIG. 2, the relationship between the opening positions is as shown in FIG. Additionally, an air cleaner 15 is installed in the chamber 12d.
One end of another control passage 17 is connected to this control passage 16 so as to branch off. This control passage 17 is opened and closed by a valve body 12a, and furthermore, an electromagnetic switching valve 18 is interposed in the middle of this control passage 17, and the other end of the control passage 17 is a control passage. Connected to 9. Further, a control passage 20 with a check valve 19 is interposed between the control passage 10 and a portion of the control passage 17 closer to the switching valve 18 than the valve opening/closing portion. Note that this check valve 19 is a valve that only allows flow from the passage 17 to the passage 10. Furthermore, the control passage 10 includes another control passage 21.
The control passage 21 has a check valve 22 interposed therein. An electromagnetic three-way switching valve 23 is connected to the other end of the control passage 21 . Furthermore, this three-way switching valve 23 has a passage 24 that communicates with a part of the intake passage 1 downstream of the part where the throttle valve 2 is disposed and introduces intake manifold negative pressure, and a passage 24 that communicates with the atmosphere via an air cleaner 25. Passage 2 that leads atmospheric pressure
6 is connected. Note that the check valve 22 is a valve that only allows flow from the three-way switching valve 23 to the passage 10. In addition, a control unit 27 is connected to each solenoid coil 18a, 23a of the switching valve 18, 23.
(a control signal for excitation during two-cylinder operation, a control signal for demagnetization during four-cylinder operation) is supplied from the engine. That is,
This control unit 27 outputs a control signal for degaussing, which requires four-cylinder operation at a higher output side than this part E, with the part indicated by reference numeral E in FIG. It is designed to output a control signal for excitation for two-cylinder operation on the low output side. Therefore, during two-cylinder operation, the solenoid coil 18a of the switching valve 18 is energized in response to a control signal for energization, and the plunger 18c is driven against the return spring 18b to open the control passage 17. Conversely, during four-cylinder operation, the solenoid coil 18a is demagnetized in response to a control signal for demagnetization, and the plunger 18 is demagnetized by the action of the return spring 18b.
c closes the control passage 17. Hereinafter, when the switching valve 18 opens the control passage 17, the switching valve 18 is referred to as on, and when the switching valve 18 closes the control passage 17, the switching valve 18 is referred to as off. During two-cylinder operation, the three-way switching valve 23 has its solenoid coil 23a energized in response to a control signal for energization, and the plunger 23c is driven against the return spring 23b to switch the control passage 21 to the atmosphere side. Conversely, during four-cylinder operation, the solenoid coil 23a is demagnetized in response to a control signal for demagnetization, and the plunger 23 is demagnetized by the action of the return spring 23b.
c switches the control passage 21 to the intake manifold negative pressure side. Hereinafter, when the three-way switching valve 23 is on the atmospheric side, the three-way switching valve 23 is said to be on, and when the three-way switching valve 23 is on the negative pressure side, the three-way switching valve 23 is called on.
3 is said to be off. By the way, a lean control valve 28 is interposed in the air bleed passage 6, and this control valve 28
is configured as a differential pressure responsive diaphragm motor. This control valve 28 includes chambers 28b and 28c separated by a diaphragm 28a that also serves as a valve body, and a spring 28d is loaded in the chamber 28b. A control passage 2 is provided in the chamber 28b of the control valve 28.
The other end of the control passage 29 is connected to a portion of the control passage 17 closer to the control passage 16 than the valve opening/closing portion. Furthermore, the three-way switching valve 23 is located closer to the check valve 22 in the control passage 29 and the control passage 21.
The side portion is connected via an orifice 30. This orifice 30 is used to ensure the operation of the control valve 28 when the VCU 12 is activated, and to ensure the operation of the control valve 28 when the VCU 12 is activated.
2 Provided to prevent interference with EGR control valve 8. Therefore, the VCU 12 and the switching valves 18, 2
The table below shows the logical conditions under which the control valves 7, 8, and 28 are turned on and off (opened and closed) according to the on-off state of No. 3.

[Table] How to read this table is as follows. For example, if VCU 12 or switching valve 18 is off,
Control valve 7 is turned on, which appears to be an OR condition. By the way, as shown in Figures 1 and 3, the cross point P in the conventional cylinder-deactivated engine is closer to the low-load side, which causes the problems mentioned above, but as is clear from Figure 3, , lower the output PS1 during 4-cylinder operation as indicated by the symbol PS1',
If the output PS2 during two-cylinder operation is increased as indicated by PS2', the cross point can be moved to the high load side as indicated by P', which is preferable. In order to achieve this, the following control may be performed. In other words, during low-speed 4-cylinder operation, the amount of EGR is increased to reduce output, while during low-speed 2-cylinder operation, the amount of EGR is reduced to the extent that exhaust gas regulations are met to increase output, and when 4-cylinder is operated at high speed, the output is increased by reducing the amount of EGR, and even a small amount of exhaust gas is reduced during high-speed 4-cylinder operation. By performing recirculation, the output can be lowered compared to the conventional type, and at the same time, during high-speed two-cylinder operation, the EGR amount can be reduced to zero to increase the output. The effects during each operation will be explained below. (1) In the case of low-speed 4-cylinder operation (region indicated by the symbol in Fig. 4) In this case, the VCU 12 and the switching valve 18,
Since control valves 23 are both off, as can be seen from the table above, control valves 7 and 8 are on, and control valve 28 is off. Therefore, in this case, the amount of EGR will be large, and lean is off (air-fuel ratio is approximately 14.2)
Therefore, the output can be lowered. (2) In the case of low-speed two-cylinder operation (region indicated by the symbol in Fig. 4) In this case, VCU12 is off and switching valve 1
Since control valves 8 and 23 are on, the control valve 7 is on and control valves 8 and 28 are off, similarly from the table above. Therefore, in this case, the amount of EGR that is allowed by the control valve 7 is small (this amount is determined within the range that clears exhaust gas regulations), and lean conversion is turned off, so the output is lower than that of the conventional one. can be raised. (3) During high-speed 4-cylinder operation (region indicated by the symbol in Figure 4) In this case, VCU12 is on, switching valve 1
Since control valves 8 and 23 are off, control valves 7 and 28 are on, and control valve 8 is off, similarly from the table above. Therefore, in this case, since the control valve 8 is off, the EGR amount is reduced and lean is achieved (the air-fuel ratio is approximately 17). This not only reduces output compared to conventional models, but also improves fuel efficiency. (4) During high-speed two-cylinder operation (region indicated by the symbol in Figure 4) In this case, VCU 12, switching valves 18, 23
Since both are on, control valves 7, 8, and 28 are all off, also from the above table. Therefore, in this case, the exhaust gas is neither recirculated nor leaned, and the output is improved. In this way, depending on the operating state, the control valves 7, 8,
28 is controlled, and the output PS1' during 4-cylinder operation and the output PS2' during 2-cylinder operation are changed as shown by the dotted line in Figure 3, so the cross point is indicated by the symbol P'. This allows the two-cylinder operating range to be expanded and fuel efficiency to be improved, as well as eliminating shock during switching. Furthermore, even when four cylinders are in operation, the engine is lean during high speed operation, so this can also contribute to improving fuel efficiency. In addition, the output PS2 during two-cylinder operation is increased as shown by the symbol PS2' in Fig. 5, and the cross point is
Even if P″ is set to the high load side, the output PS during 4-cylinder operation
1 is lowered as shown by the symbol PS1' in Fig. 6, and the cross point P is set to the high load side, the result of 2 is the same.
In addition to expanding the cylinder operating range and improving fuel efficiency, it also eliminates shock during switching. In addition, as a means of changing the air-fuel ratio for lean air-fuel ratio, in addition to the bleed air lean system that changes the carburetor characteristics and reduces the amount of fuel as in this embodiment, a lean valve is used to change the air-fuel ratio to the intake passage 1. It is also possible to adopt a proportional lean system that controls the amount of air input, but the former is preferable from the perspective of improving the shaft output at the cross point. Furthermore, the present invention can be applied not only to four-cylinder deactivated engines but also to other multi-cylinder deactivated engines, and in addition to carburetor deactivated engines, it can also be applied to fuel injection deactivated engines. can. In the case of this fuel injection method, the air-fuel ratio is controlled by adjusting the control signal to the fuel injection valve. As detailed above, according to the engine with cylinder deactivation of the present invention, by controlling the EGR amount and the air-fuel ratio, the output characteristics when operating all cylinders and the output characteristics when operating some cylinders are changed. Since the cross point can be moved to the high load side, the operating range of some cylinders can be expanded, which not only improves fuel efficiency but also has the advantage of eliminating shock during switching. be. In addition, fuel efficiency can be improved by making the engine leaner.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the output characteristics of a conventional deactivated engine, and Figs. 2 to 6 show a deactivated engine as an embodiment of the present invention, and Fig. 2 explains its schematic configuration. Schematic diagram for, 3rd,
FIG. 4 is a graph for explaining the effect thereof, and FIGS. 5 and 6 are graphs for explaining the effect of each modification. 1... Intake passage (intake system), 2... Throttle valve, 3... EGR passage, 4... Carburetor, 5... Metering device, 6... Air bleed passage, 7, 8...
EGR control valve, 7a, 8a...valve body, 7b, 8b
...Diaphragm, 7c, 7d, 8c, 8d...
Chamber, 7e, 8e... Spring, 9, 10... Control passage, 11... EGR control valve, 12... VCU,
12a...valve body, 12b...diaphragm, 12
c, 12d...Chamber, 12e...Spring, 13
... Orifice, 14 ... Control passage, 15 ... Air cleaner, 16, 17 ... Control passage, 18 ...
Switching valve, 18a... Solenoid coil, 18b...
...Return spring, 18c...Plunger, 19...Check valve, 20, 21...Control passage, 22...Check valve, 23...Three-way switching valve, 23a...Solenoid coil, 23b...Return spring, 23c... …
plunger, 24... passage, 25... air cleaner, 26... passage, 27... control unit, 28... control valve, 28a... diaphragm,
28b, 28c...chamber, 28d...spring,
29... Control passage, 30... Orifice, A...
Air-fuel ratio changing system, B...Exhaust gas recirculation system, C...Cross point control means, P, P', P'', P...Cross point.

Claims (1)

[Claims] 1. In an engine that can perform all-cylinder operation or partial cylinder operation by controlling the number of operating cylinders, the exhaust gas recirculation system that recirculates exhaust gas from the exhaust system to the intake system and the air-fuel ratio of the air-fuel mixture flowing through the intake system are In order to adjust the point at which the output during all-cylinder operation and the output during partial-cylinder operation are the same at the same throttle valve opening, the system is equipped with an air-fuel ratio change system that can be changed. A cylinder-deactivated engine, characterized in that a cross-point control means is provided for controlling the amount of exhaust gas recirculated in the exhaust gas recirculation system and for controlling the air-fuel ratio changing system.