JPS6023480Y2 - cylinder number control engine - Google Patents

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 improve when an engine is operated under a high load.For this reason, in a multi-cylinder engine, when the engine load is low, the fuel supply to some cylinders is cut to stop operation. An engine with controlled number of cylinders was devised that relatively increases the load on the remaining active cylinders by this amount and improves overall fuel efficiency in the light load range.

In this type of engine, the fuel supply means and exhaust system are usually configured independently or separately for a dormant cylinder that stops operating under light load, and for other active cylinders that are always active.

Then, air-fuel ratio sensors (oxygen concentration sensors) are placed in the exhaust systems of the dormant cylinders and working cylinders, and each fuel supply means is controlled based on the output signals of these air-fuel ratio sensors. The air-fuel ratio is independently feedback-controlled to a target value (usually the stoichiometric air-fuel ratio).

However, in this case, the air-fuel ratio sensor on the deactivated cylinder side, which needs to be kept at a relatively high predetermined temperature or higher to ensure good operation, detects the air-fuel ratio sensor in the deactivated cylinder when the deactivated cylinder enters a partial cylinder operation state in which the operation of the deactivated cylinder stops. Due to the drop in exhaust temperature on the side, the temperature may drop to an inoperable range.

Conventionally, when restarting operation of a dormant cylinder, that is, transitioning to full-cylinder operation, the air-fuel ratio feedback control of the dormant cylinder is stopped until the air-fuel ratio sensor on the dormant cylinder side warms up sufficiently, and during this period, the intake air amount is The fuel supply means on the idle cylinder side is controlled according to the situation, and the air-fuel ratio is maintained at the target value.

Therefore, when transitioning from partial cylinder operation to full cylinder operation, the air-fuel ratio control accuracy on the idle cylinder side is rough, and if the air-fuel ratio is controlled to the stoichiometric air-fuel ratio, for example, fuel efficiency will deteriorate accordingly. There is.

The present invention was developed in view of the conventional situation, and includes providing a branch passage in the exhaust passage on the side of the active cylinder, and connecting this to the exhaust passage on the side of the resting cylinder at the air-fuel ratio sensor installation part. During partial cylinder operation, high-temperature exhaust from the active cylinder is blown through this branch passage to the air-fuel ratio sensor on the idle cylinder side.
This prevents its cooling, maintains the air-fuel ratio sensor in a good operating temperature range even during partial cylinder operation, and enables immediate feedback control of the air-fuel ratio on the idle cylinder side when transitioning to full-cylinder operation. The aim is to obtain a controlled engine.

Hereinafter, an embodiment in which the present invention is applied to a type 6 six-cylinder engine will be described with reference to the drawings.

In the figure, #1. #3. #5 is a cylinder provided in bank 1 on the right side and serves as a rest cylinder, while #2. #4. #
6 is a cylinder provided in bank 2 on the left side and constitutes an operating cylinder.

Operating cylinders #2°, #4. #6 and deactivated cylinder #1゜#3.
#5, the intake passage 4 is located downstream of the throttle valve 3.
is divided into an active intake passage 5 and a rest intake passage 6.

Similarly, the exhaust passage 7 is also divided halfway into an active exhaust passage 8 and a rest exhaust passage 9.

A cutoff valve 10 is interposed at an upstream portion of the paused intake passage 6 , and the paused intake passage 6 downstream of the cutoff valve is connected to the paused exhaust passage 9 via an exhaust gas recirculation passage 11 .

Further, an exhaust gas recirculation valve 12 is interposed in the exhaust gas recirculation passage 11 .

During partial cylinder operation, the shutoff valve 10 is closed by the action of a negative pressure actuator 13 equipped with a diaphragm, and the shutoff valve 10 closes when the cylinder #1 is inactive. #3゜Cut off the fresh air supply to #5.

In conjunction with this, the exhaust recirculation valve 12 is opened by the action of the negative pressure actuator 14, and the exhaust gas recirculation valve 12 is opened by the action of the negative pressure actuator 14. #3. #
5 is made to inhale exhaust gas at approximately atmospheric pressure, and the inactive cylinder #1. #3. Reduce pumping loss in #5.

As a result, in addition to the effect of improving fuel efficiency as an engine with controlled number of cylinders, further improvement in fuel efficiency can be achieved.

On the other hand, an active air-fuel ratio sensor (oxygen concentration sensor) 15 and an inactive air-fuel ratio sensor 16 are disposed in the active exhaust passage 8 and the idle exhaust passage 9, respectively.

The air-fuel ratio signals from these air-fuel ratio sensors 15 and 16 are sent to the fuel injection control circuit 1 through input control circuits 17 and 18.
In the control circuit 19, the basic fuel injection signal determined based on the intake air amount signal from the air flow meter 20 is corrected using these air-fuel ratio signals, and the control circuit 19 corrects the basic fuel injection signal determined by the intake air amount signal from the air flow meter 20, Two corrective fuel injection signals are obtained.

Of these, the correction signals on the deactivated side are for deactivated cylinders #1, #3, and so on.
Corresponding to #5, the correction signal is sent to the fuel injection valve g L g 3t g 5 disposed in the branch part of the idle intake passage 6 via the cylinder number control circuit 21, while the correction signal on the operating side is sent to the fuel injection valve g ．． #4. Fuel injection valve g L g 4 arranged in the branch part of the working intake passage 5 corresponding to #6! g
It is sent directly to 6.

Each of the fuel injection valves g1 to g6 injects fuel according to these correction signals, but during partial cylinder operation, the cylinder number control circuit 21 cuts the correction signals to the fuel injection valves gl, g3, g5, Cutting off fuel injection from cylinder #1
．． #3. Stop the operation of #5.

This performs the basic operation of an engine that controls the number of cylinders, resulting in improved fuel efficiency.

Further, the amount of fuel injected from each of the fuel injection valves g1 to g6 is corrected by the fuel injection control circuit 19 based on signals from the air-fuel ratio sensors 15 and 16 so that the air-fuel mixture always has the stoichiometric air-fuel ratio. Feedback control is performed independently on the idle cylinder side and the active cylinder side, thereby ensuring the best combustion of the air-fuel mixture.

A three-way catalyst 22 is disposed in the exhaust passage 7 downstream of the confluence of the active exhaust passage 8 and the idle exhaust passage 9.

This catalyst 22 has the best purification characteristics for the combustion exhaust of the air-fuel mixture at the stoichiometric air-fuel ratio, so in combination with the action of the air-fuel ratio feedback mechanism described above, the catalyst 22 effectively removes harmful substances in the exhaust. be able to.

Incidentally, the active exhaust passage 8 and the idle exhaust passage 9 are also connected by a branch passage 23 in the middle thereof.

The branch passage 23 is continuously open to the wall surface of the passage opposite to the idle exhaust passage 9 near or upstream of the idle air-fuel ratio sensor 16, so that the exhaust pressure of the idle exhaust passage 9 decreases. During partial cylinder operation, operating cylinder #2.
#4. A part of the high temperature exhaust from #6 flows into this branch passage 23.
through the opening 24 of the idle side air-fuel ratio sensor 16.
It's like it's blowing at you.

If the connection opening 25 of the branch passage 23 to the working exhaust passage 8 is provided upstream of the working air-fuel ratio sensor 15, the working cylinder #2. #4. The proportion of the exhaust that passes near the operating side air-fuel ratio sensor 15 decreases by the amount of exhaust gas from #6 that flows into the branch passage 23, causing a deterioration of the air-fuel ratio detection accuracy, so as shown in the figure. The opening 25 is provided downstream of the operating air-fuel ratio sensor 15.

Now, the cylinder number control circuit 21 controls to cut off fuel injection from the fuel injection valves gLg3 and g5, and the cylinder number control circuit 21 controls the fuel injection from the fuel injection valves gLg3 and g5 to stop the cylinder #1. #3. #
5 has been deactivated and the engine is therefore in partial cylinder operation.

At this time, the active cylinder #2 is in operation. The exhaust pressure of #4゜#6 is inactive cylinder #1゜#3. Since the exhaust pressure is higher than that of #5, the operating cylinder #2. #4. #6
A part of the high-temperature exhaust gas flows out through the branch passage 23 to the idle exhaust passage 9.

At this time, the high-temperature exhaust gas flowing in from the opening 24 of the branch passage 23 blows against the idle air-fuel ratio sensor 16, so cooling of the idle air-fuel ratio sensor 16 due to a decrease in exhaust temperature on the idle cylinder side is suppressed, and the Even during cylinder operation, it is possible to maintain the idle-side air-fuel ratio sensor 16 in a temperature range that allows good operation.

Therefore, the cylinder number control circuit 21 controls the fuel injection valve gL g
3t When the cutoff of fuel injection from g5 is released and the engine shifts to all-cylinder operation, the idle side air-fuel ratio sensor 16
Since the cylinder continues to output an accurate air-fuel ratio signal, accurate feedback control for the air-fuel ratio of the idle cylinder can be started using this air-fuel ratio signal at the same time as the fuel injection cut-off is released.

In other words, unlike conventional methods, there is no need to open control the air-fuel ratio on the idle cylinder side when transitioning to all-cylinder operation, and accurate feedback control can be started immediately. It is now possible to control the air-fuel ratio to the stoichiometric ratio, improving fuel efficiency compared to conventional methods.

Moreover, this accurate stoichiometric air-fuel ratio control brings about a good purification effect of the three-way catalyst 22, and can improve the removal rate of harmful substances in the exhaust gas compared to the conventional method.

Deactivated cylinder #1. #3. Even if the operation of #5 resumes and all cylinders start operating, and high-temperature exhaust gas no longer blows to the idle air-fuel ratio sensor 16 via the branch passage 23, the idle cylinder #1. #3. Since the high-temperature exhaust gas from #5 directly warms the air-fuel ratio sensor 16, the temperature of the idle-side air-fuel ratio sensor 16 can be maintained within a good operating range in any case.

As explained above, according to the present invention, the temperature of the air-fuel ratio sensor on the idle side can be maintained within a good operating range even during partial cylinder operation. Accurate feedback control can be started.

Therefore, when transitioning to all-cylinder operation, it is possible to improve, for example, fuel efficiency and the removal rate of harmful substances in the exhaust gas by the three-way catalyst.

It goes without saying that the present invention can also be applied to similar engines with in-line cylinder arrangement.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view showing an embodiment of the present invention. 7... Exhaust passage, 8... Working exhaust passage, 9... Dormant exhaust passage, 15... Working side air-fuel ratio sensor, 16... ...Stop side air-fuel ratio sensor, 17, 18...Input control circuit, 19.
... Fuel injection control circuit, 21 ... Cylinder number control circuit, 23 ... Branch passage, 24.25 ...
...Opening, #1. #3. #5... Deactivated cylinder, #2. #4. #6...Operating cylinder,
g1 to g6...Fuel injection valves.

Claims (1)

[Scope of utility model registration request] The exhaust gas is divided into a dormant cylinder whose fuel supply is cut and the operation is stopped when the engine is lightly loaded, an operating cylinder which is always operated, and a dormant exhaust passage and an operating exhaust passage corresponding to the dormant cylinder and the operating cylinder. a passage, and means for recirculating exhaust from the idle exhaust passage only to the idle cylinder when the idle cylinder is deactivated;
Equipped with air-fuel ratio sensors for the idle cylinder side and the active cylinder side, which are arranged in the idle exhaust passage and the active exhaust passage, and independently feeds back the air-fuel ratio of the idle cylinder side and the active cylinder side based on the rain air-fuel ratio sensor output signal. In a multi-cylinder engine that is controlled, a branch passage connecting the idle exhaust passage and the working exhaust passage is provided, and an opening for connecting the branch passage to the working exhaust passage is located downstream of the working side air-fuel ratio sensor arrangement part. , and a cylinder number control engine in which the connection opening to the other idle exhaust passage is set near the air-fuel ratio sensor arrangement part on the idle side.