JPS58106145A - Cylinder quantity controlled engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a cylinder number control engine that performs partial cylinder operation by suspending the operation of some cylinders when the engine is under light load.

In general, fuel efficiency tends to be better when the engine is operated with a high load on all cylinders.For this reason, in a multi-cylinder engine, when the engine load is low, the supply of fuel and fresh air to some cylinders is cut. An engine with cylinder number control has been devised in which the load on the remaining active cylinders is increased by that amount, thereby improving overall fuel efficiency in the light load range. C% 1985-151131, previously filed by the present applicant) This engine, which was previously proposed by the present applicant, is shown in FIG.

The intake passage 1 is located downstream of the throttle sheath 72 and connects the working cylinders A to C.
It branches into an operating side intake passage 3 connected to the cylinder DF and a rest side intake passage 4 connected to the rest cylinder DF.

Among these, the upstream part of the upper body side intake passage 4 has a fresh air cutoff 9P5.
is interposed therein, and during partial cylinder operation, this shutoff valve 5 closes to cut off the supply of fresh air to the cylinders DF on the idle side.

On the other hand, the exhaust passage 6 also branches halfway into an operating exhaust passage 7 that connects to the operating cylinders A-C and an idle exhaust passage 8 that connects to the idle cylinders D-F. The passage 8 is connected to the idle-side intake passage 4 downstream of the fresh air cutoff valve 5 via an exhaust circulation passage 9.

In this exhaust circulation passage 9, a diaphragm device 1 which responds to negative pressure that is switched and controlled via a three-way solenoid valve 10 is provided.
An exhaust gas recirculation valve 12, which is opened and closed by the actuator 1, is interposed.During partial cylinder operation, this exhaust gas recirculation valve 12 opens and sucks exhaust gas at approximately atmospheric pressure into the cylinders D to F on the idle side when the operating body is stopped. let This reduces the pumping loss in the cylinders DF on the idle side, thereby further improving fuel efficiency.

Further, in the exhaust passage 6, an air-fuel ratio sensor 13 for detecting a comprehensive exhaust air-fuel ratio and a three-way catalyst 14 for exhaust purification are installed downstream of the air-fuel ratio sensor 13.

Of these, the air-fuel ratio detection signal from the sensor 13 is sent to the control circuit 1.
Sent to 5. In response to this air-fuel ratio signal, the control circuit 15 installs fuel injection valves a corresponding to each cylinder A to F.
% f (D Controls the valve opening period and feedback controls the fuel injection amount so that a mixture at the stoichiometric air-fuel ratio is obtained.

In addition, the control circuit 15 controls the fuel injection valves d-f' to remain closed during light engine load operation, and cuts off the fuel supply to the cylinders DF on the idle side. Stop operation and perform partial cylinder operation. However, in this case, the amount of intake air in the active cylinders A-C is twice that during normal operation (when all cylinders are operated) by closing the shutoff valve 5t.
Correspondingly, the control circuit 15 switches the injection constant so that the injection amount from the fuel injection 9Pa%c is also doubled. This injection amount is also controlled according to the signal from the air-fuel ratio sensor 13.

By the way, if the air-fuel ratios of the active and idle cylinders A-C%D-F are controlled by the signal from the only air-fuel ratio sensor 13, for example, the shape of the intake system and the fuel injection 9Pa-c, d -f, etc., the amount of intake air and fuel injection tend to vary between the active cylinders A-C and the idle cylinders D-F during full-cylinder operation.
In both cases, it is similarly difficult to obtain a mixture with the optimum air-fuel ratio, and the combustion condition may deteriorate, which may adversely affect exhaust performance and drivability.

Therefore, conventionally, air-fuel ratio sensors 13 are installed in each of the exhaust passages 78 on the operating side and the idle side, and depending on the detection signal of the corresponding air-fuel ratio sensor 13, the operating cylinders A to C and the idle cylinders D to It has been proposed to separately control the air-fuel ratio at

However, even if two air-fuel ratio sensors 13 are installed corresponding to the operating side and the idle side, the air-fuel ratio sensor 13 installed in the idle-side exhaust passage 8 is connected to the idle side during one partial cylinder operation. As the exhaust gas recirculates to cylinder DF', the temperature gradually decreases. For this reason, for example, when shifting to full-cylinder operation after a long period of partial-cylinder operation, the detection function of the air-fuel ratio sensor 13 decreases immediately after that, making it impossible to obtain a good air-fuel ratio value9, and as a result, Pause side cylinders D to C
There is a problem that the air-fuel ratio control at the engine is confused, which worsens the drivability, and the reaction at the catalyst 14 installed downstream of the exhaust passage 6 is inhibited, leading to an increase in harmful exhaust components.

The present invention has been made in view of these problems, and includes installing an air-fuel ratio sensor in each of the exhaust passages on the operating side and the idle side. By heating the cylinders during operation, the sensor function is always maintained in good condition, and even in full cylinder operation, partial cylinder operation, and immediately after transition from partial cylinder operation to full cylinder operation, it is possible to control the optimal air-fuel ratio in each cylinder. K to resolve the issue.
The objective is to provide an engine with controlled number of cylinders.

Embodiment 1r of the present invention will be described below based on the drawings.

As shown in Figure 2, cylinders A-C are operating cylinders that are constantly supplied with fuel and fresh air and continue to operate, whereas cylinders D-F are cut off from fuel supply in the light load range of the engine. %
This is the cylinder on the idle side through which exhaust gas is recirculated through the passage -9.

The exhaust passage 6 connecting the Q operating cylinder A-C and the idle cylinder D-FIC is correspondingly divided into an active exhaust passage 7 and an idle exhaust passage 8 up to the vicinity upstream of the catalyst 14. In this embodiment, air-fuel ratio sensors 16 and 17 are installed in the exhaust passages 7 and 8 on the operating side and the idle side, respectively.

Among these, the first air-fuel ratio sensor 16 installed in the working side exhaust passage 7 has a good detection function because it is always kept in a high temperature state by the combustion exhaust from the working cylinders AC. Therefore, a normal sensor 16 is used.

On the other hand, the second air-fuel ratio sensor 17 installed in the idle side exhaust passage 8 has a detection section 190 attached to the tip end 18 of the sensor 17, as shown in FIGS. 3 and 4, for example.
An electric heater 20 is incorporated as a heating device that heats the detection section 19111'' to a high temperature, and is integrally formed.

In this case, the heater 20 is not limited to a zigzag shape as shown in the figure, but may be incorporated in a spiral shape.

This heater 20 has a lead wire connected to the sensor 17.
Similarly to the lead wire, the lead wire is drawn out from the rear of the sensor 17, and is energized by a command from the control circuit 21 during one-part cylinder operation, as will be described later.

Also, the surrounding KVi of the detection s19 of this sensor 17.

A cylindrical protection tube 22 is attached to prevent the detection part 19 from being damaged when the sensor 17 is attached.
A plurality of sulins 231r are formed on the side surface of 2.

That is, during partial cylinder operation in which cylinders D-F are operationally stopped, 1
The second air-fuel ratio sensor 17 installed in the idle side exhaust passage 8 is heated to a high temperature state, and the detection function of the sensor 17 is maintained in good condition. This is designed so that the function of the sensor 17 can be fully demonstrated like the first air-fuel ratio sensor 16 when the all-cylinder operation starts when cylinders D-F start operating. .

And this first one. Detection signals from the second air-fuel ratio sensors 16 and 17 are input to a control circuit 21, and the control circuit 21 separately controls the air-fuel ratios in cylinders A to C and D-FK in accordance with these detection signals.

Specifically, the control circuit 21 determines the basic fuel injection amount for each cylinder A to F during all-cylinder operation, for example, based on an intake air amount signal from the air meter 24 and a signal from a rotation sensor (not shown). The calculated values are corrected according to the detection signals of the corresponding air-fuel ratio sensors 16 and 17, and the fuel injection valves a - The fuel injection amount of f is controlled by 9t.

On the other hand, the control circuit 21 closes the fresh air cutoff valve 5m+- installed in the upstream part of the intake passage 4 on the idle side and closes the exhaust air in the exhaust circulation passage 9 in the light engine load range as judged from the intake air amount signal etc. The recirculation valve 12 is opened to recirculate the exhaust gas to the cylinders D to F on the inactive side, and a command is issued to keep the fuel injection valves 9fd to fk closed, and the fuel supply to the cylinders D to F is cut to stop their operation. .

Perform partial cylinder operation.

In this case, in the working cylinders A-C, the injection constant is switched to double within the control circuit 21 so that the fuel injection amount is doubled, and at the same time, the injection amount is changed by the first air-fuel ratio sensor. According to the detection signal from 16, feedback control is performed so that the air-fuel mixture has an optimum air-fuel ratio.

At this time, the control circuit 21 issues an energization command to the heater 20 incorporated in the air-fuel ratio sensor 17 of F2, and
Seven sensor detection units 1911 - Heating. This prevents the temperature of the sensor 17 from becoming low due to the exhaust gas flowing back into the idle cylinder D-F' during the S-minute cylinder operation, maintains the high temperature state, and after that, all the cylinders The detection function of the sensor 17 is fully demonstrated when the operation shifts to the cylinder D~
Avoid confusion in air-fuel ratio control at F.

In this embodiment, air-fuel ratio sensors 16+17 are installed in each of the exhaust passages 7 and 8 on the operating side and the idle side, and the corresponding cylinders A-C and D- are installed in accordance with these detection signals.
In addition to separately controlling the air-fuel ratio of F, an electric heater 20 is built into the detection s19 of the air-fuel ratio sensor 17 on the idle side, and this sensor 17 is used during partial cylinder operation when the temperature is likely to be lowered. Since it was heated, the rain air-fuel ratio sensor 1
6.degree. 17, the detection function can be maintained well at all times, and the optimum air-fuel ratio in each cylinder A to F can be controlled regardless of the operating conditions.

Therefore, there is no variation in the air-fuel ratio between the active cylinders A-C and the idle cylinders D-F, and a mixture at the stoichiometric air-fuel ratio can be obtained, resulting in combustion during full cylinder operation and partial cylinder operation. The condition will be improved, and the exhaust performance and drivability will be improved.

Even immediately after transitioning from partial cylinder operation to full cylinder operation, it is possible to obtain a good detection value agreement from both sensors 16.17, making air-fuel ratio control more stable and accurate, and further improving engine performance. I can figure it out.

Note that in this embodiment, the air-fuel ratio sensor 17 on the idle side
An electric heater 20 is built into the sensor detecting section 19 and is formed integrally with the sensor detecting section 19. For example, as shown in FIG. There are no particular restrictions on the heating means, such as installing heaters 25 in seven spirals along the circumferential surface.

As explained above, according to the invention, the air-fuel ratio sound of the corresponding cylinders on the active side and the idle side is controlled separately according to the detection signal of the air-fuel ratio sensor installed in the exhaust passage on the active side and the idle side, respectively. The air-fuel ratio sensor on the idle side, which tends to cool down during partial cylinder operation, is heated to maintain a high temperature.As a result, the air-fuel ratio sensor can always detect the air-fuel ratio in the exhaust gas from each cylinder. Even during cylinder operation and immediately after transitioning from partial cylinder operation to full cylinder operation.

This has the effect that the air-fuel ratio in each cylinder can be optimally controlled.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a sectional view of an embodiment of the present invention. Fig. 4 is a partial side view thereof, and Fig. 5- is a sectional view of a main part showing another embodiment of the present invention. 2... Throttle valve, 3... Working side intake passage, 4... Stopping side intake passage, 5... Fresh air cutoff valve, 7... Working side exhaust passage, 8... Stopping side intake Passage, 9... Exhaust circulation passage, 12... Exhaust recirculation valve, 14... Three-way catalyst, 16...
...First air-fuel ratio sensor, 17... Second air-fuel ratio sensor, 19... Detection section, 20... Heater, 21...
Control circuit, 22...protection! , 24...Air 70-unit, 25...Heater. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] In a multi-cylinder engine that has a dormant cylinder that stops operating when the fuel supply is cut off in the light load range of the engine, and an active cylinder that is constantly supplied with fuel and fresh air and continues to operate,
The exhaust passage is divided into sections upstream of the catalyst corresponding to the cylinders on the idle side and the cylinders on the active side, and a first air-fuel ratio sensor is installed in the active side exhaust passage, and a second air-fuel ratio sensor is installed in the idle side exhaust passage. In addition to installing a heating device for heating the second air-fuel ratio sensor, this heating device heats the second air-fuel ratio sensor when the operating body is stopped, and also heats the second air-fuel ratio sensor when the operating body is stopped. A cylinder number control engine characterized by comprising a control circuit that controls the air-fuel ratio of a corresponding operating cylinder and a non-operating cylinder according to a detection signal.