JPS5853181B2 - cylinder number control engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder number control engine that suspends operation of some cylinders when the engine is under light load and recirculates exhaust gas to these idle cylinders.

-Generally, fuel efficiency tends to improve when an engine is operated under a high load condition. Therefore, in a multi-cylinder engine, the supply of fuel and fresh air to some cylinders is cut when the engine load is low. An engine with controlled number of cylinders was devised in which the load on the remaining operating cylinders is increased by that amount, thereby improving overall fuel efficiency in the light load range.

In this type of engine that was previously invented by the present applicant, as shown in FIG.
Close the shutoff valve 3 located in the cylinder to cut off the supply of fresh air to the idle cylinders #4 to #6, and then open the exhaust recirculation valve 4 to open the passage 5.
Exhaust gas at approximately atmospheric pressure is introduced into the intake systems of cylinders #4 to #6 to reduce pumping loss in cylinders #4 to #6, which are inactive, thereby further improving fuel efficiency.

However, during partial cylinder operation in which only active cylinders #1 to #3 are in operation, the opening of the throttle valve is relatively small, so the pumping action of cylinders #1 to #3 causes the throttle valve to be shut off downstream and shut off. Since the negative and positive levels in the intake passage upstream of the valve increase considerably, the introduced exhaust gas at approximately atmospheric pressure, which is filled downstream of the cutoff valve, leaks into the operating cylinders #1 to #3 even through a small gap in the cutoff valve 3. .

Therefore, the operation of the operating cylinders #1 to #3 is inhibited, resulting in a problem that the engine becomes unstable during partial cylinder operation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the exhaust gas introduced into the intake system of a dormant cylinder during partial cylinder operation from leaking into an active cylinder, thereby stabilizing the operation particularly during partial cylinder operation.

This will be explained below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which 6 is an intake passage;
Reference numeral 7 denotes an intake flow rate sensor provided in the intake passage 6.

Downstream of the flow rate sensor 7, the intake passage 6 branches into a rest intake passage 6a and an active intake passage 6b. Connected to cylinders #1 to #3.

The idle cylinders #4 to #6 are cylinders whose operation is suspended during partial cylinder operation, and the active cylinders #1 to #3 are cylinders which are constantly activated.

The idle intake passage 6a is provided with a cutoff valve 8 located at the most upstream portion and a throttle valve 9a located downstream thereof.

During partial cylinder operation, this shutoff valve 8 closes and the idle cylinders #4 to
Cut off the fresh air supply to #6.

On the other hand, the operating intake passage 6b is provided with a throttle valve 9b at a position opposite to the position where the throttle valve 9a is provided.

These throttle valves 9a and 9b open and close in phase with each other in conjunction with the accelerator pedal to supply the same flow rate of fresh air to the operating cylinders and the idle cylinders.

Further, the exhaust passage 10 is also branched into a rest exhaust passage 10a and an active exhaust passage 10b, with the rest exhaust passage 10a being connected to the resting cylinders #4 to #6, and the working exhaust passage 10b being connected to the working cylinder #1.
- Connected to #3 respectively.

A pause intake passage 6a and a pause exhaust passage 1 downstream of the throttle valve 9a
0a is connected to the exhaust gas recirculation passage 11, and an exhaust gas recirculation valve 12 interposed in the middle of the exhaust gas recirculation passage 11 opens during partial cylinder operation to stop exhaust gas at approximately atmospheric pressure from the intake passage 6a.
to be introduced.

Next, further explanation will be given focusing on the operation.

During partial cylinder operation, the shutoff valve 8 closes and the idle cylinders #4 to
At the same time as cutting off the supply of fresh air to #6, the exhaust recirculation valve 1
2 opens to introduce exhaust gas at approximately atmospheric pressure into the idle intake passage 6a downstream of the throttle valve 93.

The throttle valve 9a is replaced by the throttle valve 9b when the accelerator pedal is depressed.
Since the angle is the same as that, the introduced exhaust gas at approximately atmospheric pressure passes through the gap in the throttle valve 9a, so that the entire downstream area of the shutoff valve 8 eventually becomes approximately atmospheric pressure.

On the other hand, since the load is light, the opening degree of the throttle valve 9b is relatively small, and therefore, due to the suction action of the operating cylinders #1 to #3, the operating intake passage 6b downstream of the throttle valve 9b reaches a considerably high negative pressure.

However, at this time, the intake passage 6 on the upstream side of the cutoff valve 8 and the upstream side of the throttle valve 9b is filled with fresh air at approximately atmospheric pressure. Therefore, the recirculated exhaust gas at approximately atmospheric pressure that fills the downstream side of the shutoff valve 8 hardly leaks upstream through the small gap in the shutoff valve 8.

As a result, the flow rate of exhaust gas that passes through a region filled with fresh air at approximately atmospheric pressure from the downstream side of the shutoff valve 8 and is drawn into the downstream side of the throttle valve 9b, that is, into the operating cylinders #1 to #3, becomes extremely small. , the operation of the operating cylinders #1 to #3 is not obstructed.

In other words, the throttle valve 9a is located downstream of the branch point of the intake passage.
, 9b and the cutoff valve 8 (in this embodiment, the cutoff valve 8 is replaced by the throttle valve 9a).
(Although it was installed upstream of the cylinder, it may also be installed downstream). During partial cylinder operation, instead of separating the intake system of the idle cylinder and the intake system of the operating cylinder only with a shutoff valve as in the past, a shutoff valve is installed. Since a space filled with fresh air at approximately atmospheric pressure where no pressure difference occurs before and after the valve is partitioned off, it is possible to effectively prevent recirculated exhaust gas from leaking into the operating cylinders.

By the way, when all cylinders are in operation, the exhaust gas recirculation valve 12 closes to cut off the recirculation of exhaust gas, and at the same time, the shutoff valve 8 opens and the throttle valve 9 is opened to the idle cylinders #4 to #6 as well as to the operating cylinders #1 to #3.
Fresh air is supplied at the same flow rate as the operating cylinders regulated by a.

In addition, in the above embodiment, the amount of intake air during partial cylinder operation is smaller than during full cylinder operation, so even if the accelerator opening is the same, the throttle valve opening will be lower during partial cylinder operation than during full cylinder operation. If the total intake air flow participating in combustion remains unchanged by increasing the amount of air, favorable results can be obtained in terms of operational performance.

As another method, for example, a passage that bypasses the throttle valve 9b and sends fresh air to the operating cylinder, and a valve that regulates the flow rate of the passage are provided, and during partial cylinder operation, the valve is opened to allow fresh air to flow from the bypass passage. A method such as supplying fresh air may also be used.

As explained above, the present invention provides a throttle valve in each of the idle intake passage and the active intake passage downstream of a branch point, and also provides a cutoff valve in the idle intake passage, so that the downstream of the cutoff valve and the throttle valve are provided in the idle intake passage. Since fresh air at approximately atmospheric pressure is sandwiched between the intake passage and the downstream working intake passage, it is possible to prevent the recirculated exhaust gas that has filled up downstream of the shutoff valve from leaking into the working intake passage downstream of the throttle valve and being sucked into the working cylinder. Can be effectively prevented.

Therefore, the stability of the engine during partial cylinder operation can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a conventional engine, and FIG. 2 is a schematic sectional view showing an embodiment of the present invention. 6... Intake passage, 6a..., Inactive intake passage, 6b... Working intake passage, 8... Shutoff valve, 9a, 9b... - Throttle valve, 11...
...Exhaust recirculation passage, 12...Exhaust recirculation valve, #
1, #2, #3, #4, #5, #6...
··cylinder.

Claims (1)

[Scope of Claims] 1. A dormant cylinder whose operation is stopped and exhaust gas is recirculated when the engine is under light load, the remaining working cylinders which are always in operation, an active intake passage connected to the working cylinder, and a dormant intake passage connected to the dormant cylinder. In an engine with cylinder number control, which is equipped with an intake passage that branches off from the middle of the intake passage, and a cutoff valve that closes when the engine is under light load, which is provided in the idle intake passage, there is an intake passage that is located downstream of the branch point of the intake passage and is An engine that controls the number of cylinders with each throttle valve interlocked with the idle intake passage. 2. The cylinder number control engine according to claim 1, wherein the operating intake passage is provided with a passage that bypasses the throttle valve, and this bypass passage is opened during partial cylinder operation.