JPS58222937A - Engine controlled in number of operating cylinders - Google Patents

Abstract

PURPOSE:To ensure the braking action of a multicylinder engine including a shutoff valve for cutting off the intake to stoppable cylinders and a fresh air intake valve for introducing fresh air into the stoppable cylinders, by keeping both the valves in an all-cylinder-operating state when the rotational frequency of the engine is not lower than a prescribed level during the deceleration of the engine. CONSTITUTION:In a multicylinder engine including stoppable cylinders A-C and continuously working cylinders D-F, a shutoff valve 11 which is closed throughout the partial cylinder operation of the engine and an air flow meter 8 are provided at the inlet port of an intake passage 4 for the stoppable cylinders and a fresh air intake valve 13 is provided in a by-pass 12 around a throttle valve 1. When a throttle valve full opening signal from a throttle valve switch 9 and a signal showing that the rotational frequency of the engine is not lower than a prescribed level are applied to a control circuit 10 during the deceleration of the engine, fuel to all the cylinders is cut off and the shutoff valve 11 is opened and the fresh air intake valve 13 is closed to suppress the inflow of a large amount of fresh air from the by-pass 12 into the stoppable cylinders A- C to keep the effect of the braking action of the engine good.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder number control engine that performs partial cylinder operation by suspending the operation of some cylinders in a light engine load range or the like.

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

An example of this cylinder number control engine (Japanese Patent Application Laid-Open No. 55-1315
40, etc.) in FIG. 1, the intake passage 2 is operated downstream of the throttle valve 1 corresponding to cylinders A-C on the idle side and cylinders D-F' on the active side. The exhaust passage 5 is also divided halfway into an active exhaust passage 6 and a rest exhaust passage 7.

When stopping the operation of cylinders A to C when the engine is under light load or when there is no load, for example, the air flow meter 8
Based on the intake air amount signal from the engine, the engine speed signal from the ignition coil (not shown) as the engine speed detection means, the idle signal from the throttle valve switch 9 as the means for detecting whether the throttle valve 1 is fully idle, etc., the control circuit 10 is cylinder A-C
The fuel injection valves a to c corresponding to the above are held fully closed to cut the fuel supply, and the fresh air introduction valve 13 at the upstream part of the inactive side intake passage 4 is opened to stop the fresh air on the upstream side. Sufficiently supplies the side cylinders A to C. In the carburetor system, the inflow of the air-fuel mixture is cut off by closing the cutoff valve 11.

As a result, partial cylinder operation is performed by operating only the working side air wJD to F while reducing the pumping loss in the idle side cylinder A-e, thereby improving fuel efficiency.

In addition, 14.15 in the figure is a catalyst for exhaust purification.

16.17 is an oxygen sensor that detects the air-fuel ratio, 18°19
shows a three-way solenoid valve that selectively guides the negative pressure of the vacuum tank 22 to the diaphragm device 20.21 of 9P11.13, 23 is an exhaust gas recirculation passage, and 24 is an EGR valve.

By the way, in such a cylinder number controlled engine, in order to maintain good fuel efficiency, not only some cylinders but all cylinders A-
According to the control system shown in the flowchart in Figure 2, throttle valve 1 closes regardless of the operating status of all cylinders or partial cylinders. When the vehicle starts decelerating, the throttle valve switch 9
is turned ON, the shutoff valve 11 is closed and the fresh air introduction valve 13 is opened.

At this time, if the engine speed NE is in a relatively high range (Nz > Ncl), fuel supply to all cylinders A-F' is cut, and if it is low, the deceleration range is narrow, so fuel supply to some cylinders A-C is cut. Cuts only the fuel supply and shifts to partial cylinder operation.

After fuel cut to all cylinders A-F, when the rotational speed NE drops to a certain level (Ng = NC2), fuel supply to active cylinders D-F is resumed as shown in Figure 3, and partial cylinder operation is also started. (Idle driving) is not done 1.゛、
Ru.

In this way, fuel consumption is reduced and exhaust performance is maintained at a good level during deceleration, when combustion tends to deteriorate. .

However, in such control, when the throttle valve 1 closes and the throttle valve switch 9 turns ON during deceleration operation, the position of each valve 11, 13 immediately becomes a partial cylinder state. There was a problem in that a large amount of fresh air was drawn into A-C from the fresh air intake valve 13, and as a result, the effectiveness of engine braking when all cylinders were cut off was reduced5. load) when decelerating from operation.

A large amount of air flows into one of the catalysts 15, which is heated to a high temperature,
There was a concern that this would cause deterioration of the catalyst 15.

This invention was made with attention to this problem, and even if the throttle valve switch is turned on during deceleration, if the engine speed is above a predetermined value and the fuel supply to all cylinders is in the cut-off range. aims to solve the above-mentioned problems by keeping both the cutoff valve and the fresh air introduction valve in the same position as all cylinders.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 4 is a flowchart showing an embodiment of the control circuit of the present invention, and the mechanical configuration of the engine to which this is applied is almost the same as that in FIG. 1. 1 is fully closed and the engine starts decelerating, the throttle valve switch 9 is turned on, and in response, the engine speed NE from the speed detection means is set to the preset cylinder number switching speed NA during deceleration. be compared.

Regardless of the driving condition, NE >
If NA, fuel is injected from all fuel injection valves a - f,
All-cylinder operation is performed by opening the cutoff valve 11 and closing the fresh air introduction valve 13. If NB≦NA, fuel supply to some cylinders A to C is cut off, and the cutoff valve 11 is closed and the fresh air introduction valve 13 is operated. is opened to perform partial cylinder operation.

In this all-cylinder operating state, N is all cylinders A.
- It is compared with the upper limit rotation speed NCI which is the sum of the fuel cut range to F, and when NE > NCI, all fuel injection valves a -
C is kept fully closed, and fuel supply to all cylinders A to F is cut off. The rotation speed NE gradually decreases to the lower limit (low speed) rotation speed N
When it becomes equal to C2, fuel supply to all cylinders A to F is resumed under the condition of NK>NA.

Once the vehicle returns to deceleration driving with all cylinders running. On the other hand.

When NE≦N0, deceleration driving with all cylinders operation continues. .

During deceleration running, the % cutoff valve 11 and the fresh air intake 13 are maintained in the order of all cylinders, and after this, NE further decreases until NE=
When the engine becomes NA, the engine shifts to partial cylinder operation as described above.

This NA is set to a first switching rotation speed NAI and a second switching rotation speed NA' corresponding to the driving state when deceleration driving is started.
2 is added, and when decelerating from full-cylinder operation, NAI is 1 part @ When decelerating from low-speed operation, NA2 is selected.

Also, -NC1,>NA2>NC2>NAI is raised, thereby completely preventing hunting when changing the number of cylinders.

During deceleration, if the throttle valve 1 is opened, all cylinders and one partial cylinder operation will be performed depending on the load condition at that time.In other words, during deceleration when the throttle valve 1 is fully closed, the engine rotation will increase. Number'
f5+foot value or more (E>Ncx), fuel cut to all cylinders A to C is performed while maintaining the cutoff valve 11 and fresh air introduction W13 in the all cylinder state. .

Then, the number of revolutions decreases below the PJrf value (NE≦NA
), the fuel supply to the partial cylinders D-F is resumed, the cutoff valve 11 is closed, the fresh air introduction valve 13 is opened, and a transition is made to partial cylinder operation. Similarly, when the rotational speed at the initial stage of deceleration is below a predetermined value, partial cylinder operation continues as it is. FIG. 5 shows changes in the shape of the vehicle during deceleration.

With this configuration, during deceleration, the cutoff valve 11 and the fresh air introduction valve 13 remain in the partial cylinder state, and all cylinders A
The fuel supply to ~F is never cut off, the cutoff valve 11 is always opened in the fuel cut region, and the fresh air introduction 9f13 is closed.

Therefore, as in the conventional example, a large amount of fresh air flows from the fresh air supply passage 12 into the idle cylinders A to C.

This prevents the effectiveness of the engine brake from deteriorating and allows stable deceleration driving.

In addition, there is no need to worry about a large amount of air flowing into the catalyst 15, which has wide shoulders, and it is possible to maintain its function well and improve exhaust performance.In addition, when the engine speed becomes low, partial cylinder operation is started. , a certain amount of output is ensured in the latter half of deceleration, and fuel efficiency can be sufficiently improved.

As explained above, according to the present invention, even if the throttle valve is fully closed, when the engine speed is below a predetermined value and the fuel is in the fuel cut region for all cylinders, both the cutoff valve and the fresh air introduction valve are maintained in the all cylinder state. When the engine speed drops below a predetermined value, the engine starts decelerating through partial cylinder operation, which has the effect of ensuring good engine braking and preventing deterioration of the catalyst. be.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the configuration of a conventional example, Fig. 2 is a control flowchart thereof, Fig. 3 is an explanatory diagram of its operation, and Fig. 4 is a 70-chart showing an embodiment of the control circuit of the present invention. 51
is an explanatory diagram of its action. 1... Throttle valve, 2... Intake passage, 5... Exhaust passage, 8
... Air flow meter %9 ... Throttle valve switch, 11
. . . Key cutoff valve, 12. . . Fresh air supply passage, 13. . . Fresh air introduction valve. 14.15...Catalyst. Patent Applicant: Nissan Motor Co., Ltd. Figure 2-230- Figure 3 Text 1'+ 4 Figure 5 Ir〉 (tube

Claims (1)

[Claims] In addition to providing a shutoff valve that cuts off the supply of fuel and fresh air to some cylinders when there is no load when the engine is under light load, the air flow meter to the cylinder on the idle side is biased when the engine is at rest. In a multi-cylinder engine, there is a means to detect the engine speed, a means to detect when the throttle valve is fully closed, and a means to detect when the throttle valve is fully closed. when. Cuts off the fuel supply to all cylinders, opens the cutoff valve, and closes the fresh air introduction valve, and when the following conditions occur, starts supplying fuel to some cylinders, closes the cutoff valve, and opens the fresh air introduction valve. A control circuit for controlling the number of cylinders.