JPS6225858B2 - - 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 cutting fuel supply to some cylinders and suspending their operation when the engine is under light load.

In general, fuel efficiency tends to improve when the engine is operated under a high load, so in a multi-cylinder engine, when the engine load is low,
An engine that controls the number of cylinders cuts the fuel supply to some cylinders to stop operation, increases the load on the remaining operating cylinders by that amount, and improves overall fuel efficiency in the light load range. it was thought.

In such engines, the explosion cycle becomes longer in the partial cylinder operating range where some cylinders stop operating, which can cause engine rotation to become unstable and vibrations in the engine body to increase. .

Therefore, especially during low-speed steady driving where there is a strong possibility that the engine may become unstable, all cylinders are forced to operate even in a load range where partial cylinder operation would normally be performed, thereby stabilizing engine operation. and its vibrations are suppressed.

That is, by narrowing the partial cylinder operating range, regardless of whether the engine is actually unstable,
This is aimed at stabilizing engine operation at the expense of improving fuel efficiency.

The present invention has been made in view of the above-mentioned conventional circumstances.As a means for detecting the stability of engine operation, a sensor is provided to detect vibrations in the engine body, and based on the sensor output signal, partial cylinder operation is performed. By forcibly operating all cylinders only when the vibration of the engine body becomes larger than a predetermined level in the range and engine operation becomes unstable, the partial cylinder operating range can be narrowed only when necessary. The object of the present invention is to obtain an engine with controlled number of cylinders that can stabilize engine operation and suppress its vibration while maximizing the effect of improving fuel efficiency as an engine with controlled number of cylinders.

This will be explained below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention.

In the figure, 1 is an intake passage, and 2 is a throttle valve interposed in the intake passage 1.

On the downstream side of the throttle valve 2, the intake passage 1 connects cylinders #4 to
Working side intake passage 4 connected to #6 and cylinders #1 to
It branches into an inactive side intake passage 5 connected to #3, and a cutoff valve 6 is interposed in an upstream portion of the inactive side intake passage 5.

Furthermore, fuel injection valves g1 to g6 corresponding to cylinders #1 to #6 are interposed in downstream branch portions of these intake passages 4 and 5.

For example, when the engine moves into the light load region,
At the same time as the shutoff valve 6 is closed by a signal from the control circuit 12, which will be described later, fuel injection from the fuel injection valves g1 to g3 is interrupted, and the supply of fuel and fresh air to the cylinders #1 to #3 is cut off. Ru.

As a result, the operation of cylinders #1 to #3 is stopped and partial cylinder operation is performed in which only cylinders #4 to #6 are operated, thereby improving fuel efficiency.

However, during this partial cylinder operation, since the isolation valve 6 is closed, a very large negative pressure is generated on the downstream side of the isolation valve 6 due to the pumping action of the cylinders #1 to #3, resulting in a pumping loss in the cylinders #1 to #3. increase

Therefore, the intake passage 5 on the idle side downstream of this shutoff valve and the exhaust passage 7 are connected by an exhaust recirculation passage 8, and
An exhaust gas recirculation valve 9 is interposed in the exhaust gas recirculation passage 8, and during partial cylinder operation, the exhaust gas recirculation valve 9 is opened to introduce exhaust gas at approximately atmospheric pressure to the downstream side of the cutoff valve 6, and the exhaust gas is introduced into the cylinders #1 to ##. 3, the pumping loss is reduced to further improve fuel efficiency.

The amount of fuel injected from the fuel injection valves g1 to g6 is based on the output signal of an intake air amount sensor (not shown), and is feedback-corrected by the output signal of an air-fuel ratio sensor (not shown), so that the air-fuel ratio of the air-fuel mixture is always at a predetermined target. The fuel injection control circuit 1
Increase/decrease is controlled via 2.

On the other hand, a vibration sensor 14 is attached to the side of the engine body 13 housing each cylinder #1 to #6, etc., and its output signal indicating the vibration level of the engine body 13 is sent to the control circuit 12. ing.

Next, further explanation will be given including the overall operation. When the engine shifts to the light load range, the control circuit 12 performs cut control on fuel injection from the fuel injection valves g1 to g3 as described above, so the operation of cylinders #1 to #3 is stopped and all-cylinder operation is replaced. Partial cylinder operation is then performed.

At the same time, a signal from the control circuit 12 closes the cutoff valve 6 and opens the exhaust recirculation valve 9.
Since almost atmospheric exhaust gas is taken into cylinders #1 to #3, pumping loss in cylinders #1 to #3 is reduced, and in addition to the fuel efficiency improvement effect of an engine that controls the number of cylinders, fuel efficiency is further improved. is planned.

In this case, as shown in FIG. 2, when the vibration level of the engine body 13 becomes larger than a predetermined value A and the engine operation becomes unstable, the control circuit 12 immediately performs the cut control described above. At the same time, the shutoff valve 6 is opened and the exhaust recirculation valve 9 is controlled to be closed, thereby forcibly resuming operation of all cylinders.

At that time, after switching to all-cylinder operation,
While the predetermined value A is temporarily raised, all cylinders continue to operate for at least a predetermined time t ₀ to prevent control hunting.

As a result, compared to conventional engines that operate on all cylinders in advance in areas where the engine may become unstable, the engine is forced to operate on all cylinders only when the engine actually becomes unstable. As a result, while expanding the partial cylinder operating range, it is possible to prevent instability of engine operation and increase in vibration, and the fuel efficiency improvement effect of an engine with cylinder number control can be further improved.

As explained above, in the present invention, a sensor is provided to detect the vibration of the engine body, and when the vibration level of the engine body exceeds a predetermined level in the partial cylinder operation state, all cylinder operation is forcibly performed. As a result, compared to conventional engines, the partial cylinder operation range can be expanded, and while making the most of the fuel efficiency improvement effect of a cylinder number control engine, it is possible to stabilize engine operation and prevent an increase in vibration levels. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, and FIG. 2 is a time chart showing its operation. DESCRIPTION OF SYMBOLS 1... Intake passage, 2... Throttle valve, 4... Working side intake passage, 5... Inactive side intake passage, 6... Shutoff valve, 7... Exhaust passage, 12... Control circuit, 13...
...Engine body, 14...Vibration sensor, g1 to g
6... Fuel injection valve, #1 to #6... cylinder.

Claims (1)

[Claims] 1. In a multi-cylinder engine that has a cylinder on the idle side that stops operating when the fuel supply is cut off when the engine is under light load, and another cylinder on the operating side that operates all the time, a sensor is installed to detect vibrations in the engine body. During partial cylinder operation in which the operation of the side cylinder is stopped, if the vibration level of the engine body exceeds a predetermined value based on the output signal of the sensor, the operation of the idle side cylinder is forcibly restarted. Cylinder number control engine.