JPH0444092B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is capable of switching between an all-cylinder operation in which output is output from all cylinders and a reduced-cylinder operation in which output is output only from some cylinders, depending on the operating state of the engine. The present invention relates to a fuel control device for an engine that controls the number of cylinders.

(Prior art) In recent years, there has been a desire to significantly improve fuel efficiency, especially in automobile engines, and for this reason, for example, as shown in Japanese Patent Application Laid-Open No. 57-338, the above-mentioned Engines that control the number of cylinders have appeared in which cylinder operation and cylinder reduction operation can be switched and selected as appropriate. In other words, during high loads such as when starting or driving at high speeds, fuel is supplied to all cylinders and output is output from all cylinders, while during constant loads such as when driving at a constant speed or on a steady road,
Fuel efficiency is reduced by cutting off the fuel supply to some cylinders and increasing the filling efficiency to other cylinders.

Such a cylinder number control engine is provided with a cylinder number control means for cutting fuel supply to some cylinders and switching to deceleration operation, and
It detects engine operating conditions such as engine speed, throttle valve opening, intake load pressure, and engine temperature, determines whether deceleration operation is to be performed or not, and outputs the result of this determination to the cylinder number control means. Equipped with a means of discrimination.

Recently, as part of efforts to improve fuel efficiency, it has been proposed to cut off fuel supply during deceleration, as shown in Japanese Unexamined Patent Publication No. 7021/1983. However, if the fuel supply is completely cut off,
During the next steady run or acceleration after deceleration, the fuel supplied cannot keep up with the increase in the amount of intake air, causing the air-fuel ratio to become temporarily lean, resulting in a transition to the next run as described above. This results in a problem of poor responsiveness. In other words, during deceleration, the inside of the intake passage becomes high negative pressure, so the fuel adhering to the inner wall of the intake passage peels off and is rapidly sucked into the fuel chamber, but when the engine shifts to driving conditions such as acceleration. While the increasing intake air is quickly supplied to the fuel chamber, a portion of the supplied fuel adheres to the inner wall of the intake passage, so the air-fuel ratio is diluted by at least the amount of this adhesion. Become.

For this reason, instead of completely cutting off the fuel supply during deceleration, it is conceivable to supply a small amount of deceleration fuel to keep the inner wall of the intake passage constantly wet.

However, in the case of an engine with controlled number of cylinders, there is a difference in the magnitude of intake negative pressure during deceleration, that is, the degree of wetness (also considered as the degree of dryness) of the inner wall of the intake passage, between full-cylinder operation and reduced-cylinder operation. Therefore, some kind of countermeasure is desired in order to reduce the amount of deceleration fuel as much as possible to save fuel and ensure responsiveness when transitioning to the next run.

(Object of the Invention) The present invention has been made in consideration of the above-mentioned circumstances, and is a method for controlling the number of cylinders so that appropriate deceleration fuel can be obtained depending on the operating mode of full-cylinder operation and reduced-cylinder operation. The purpose of the present invention is to provide a fuel control device for an engine.

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, the magnitude of intake negative pressure during deceleration, that is, the degree of dryness of the inner wall surface of the intake passage, is lower during full-cylinder operation than during reduced-cylinder operation. Taking note of the fact that is larger, the amount of deceleration fuel is set to be less during reduced-cylinder operation than during full-cylinder operation.

Specifically, the configuration is as shown in FIG. That is, a cylinder reduction determination means for determining whether or not a cylinder reduction operation region is in which some cylinders are deactivated according to the operating state of the engine; A cylinder number control device that cuts intake air supply to some of the cylinders to deactivate the some of the cylinders, a fuel adjustment device that supplies fuel to an intake passage of the engine, and a deceleration detection device that detects a deceleration state. , receiving the outputs from the deceleration means and the cylinder reduction determination means, controls the fuel adjustment device to supply a small amount of deceleration fuel to the operating cylinders during deceleration, and to reduce the amount of the deceleration fuel to the cylinder reduction. The configuration includes a deceleration fuel control means that reduces fuel consumption during operation compared to when all cylinders are operated.

(Embodiment) In Fig. 2, 1 is the main body of the engine, and intake air is supplied to the combustion chamber 7 via the air cleaner 2, throttle chamber 4, intake manifold 5, and intake port 6, and the intake air is supplied from the air cleaner 2 to the combustion chamber 7. The path up to the port 6 constitutes an intake passage 8. The intake air flowing through the intake passage 8 is mixed with fuel from a fuel injection valve 10, and the amount of intake air is controlled by a throttle valve 11. Furthermore, the exhaust gas from the fuel chamber 7 is discharged into the atmosphere from the exhaust port 12 through the exhaust manifold 13 and the like.

The intake valve 14 that opens and closes the intake port 6 and the exhaust valve 15 that opens and closes the exhaust port 12 are opened and closed at predetermined timing by a valve mechanism. In the embodiment, this valve operating mechanism includes turn springs 16 and 17 that bias the intake and exhaust valves 14 and 15 in the valve closing direction.
In addition, it is generally composed of a camshaft 18 rotationally driven by a crankshaft (not shown), a cam 19 provided on the camshaft, rocker arms 20, 21, and tappets 22, 23 that constitute rocking fulcrums of the rocker arms 20, 21. has been done. In the embodiment, the engine main body 1 is for four cylinders, and the ignition order is 1-3-4-2, and the first cylinder and the fourth cylinder are stopped during cylinder reduction operation, i.e., the fuel supply is stopped. Therefore, the valve drive control devices 24, 2 are connected to the tappets 22, 23 for the 1st and 4th cylinders.
5 is attached.

The valve drive control devices 24 and 25 are switched and driven by solenoids 26 and 27, respectively, and when the solenoids 26 and 27 are demagnetized,
When the rocker arms 20, 21 of the tappets 22, 23 are at positions displaced downward in the figure, the rocker arms 20, 21 swing in response to the rotation of the camshaft 18, and the intake/exhaust valves 14 of all cylinders are moved. , 15 are opened and closed, resulting in an all-cylinder operation. vice versa,
When the solenoids 26 and 27 are energized, the above-mentioned rocking fulcrum can be displaced upward in the figure, and the interlocking relationship between the camshaft 18 and the intake/exhaust valves 14 and 15 is cut off, and the number 1 and 4 cylinders are intake/exhaust valve 14,
15 The valve remains closed and the supply of intake air is cut off, resulting in a reduced-cylinder operation in which the fuel supply is also cut off.

The above-mentioned valve drive control devices 24 and 25 themselves are already well known as shown in, for example, Japanese Unexamined Patent Publication No. 52-56212, so detailed explanation thereof will be omitted.

Reference numeral 28 in FIG. 2 is a control unit consisting of a microcomputer, and the control unit 28 controls the solenoid 26, 27, as well as the fuel injection amount, ignition timing, etc., but in the following explanation, explanation of parts that are not directly related to the present invention, such as ignition timing, will be omitted. do.

The control unit 28 receives the position of the throttle valve 11 from the throttle sensor 3, the engine cooling water temperature as the engine temperature from the cooling water temperature sensor 29, and the intake air temperature from the intake air temperature sensor 30 provided in the intake passage 8. , the intake negative pressure detected by the intake negative pressure sensor 31, and the engine rotational speed from the ignition coil 32 are respectively inputted, while the control unit 28 inputs the intake air pressure detected by the intake air negative pressure sensor 31, and the engine speed from the ignition coil 32.
Output for.

In addition, 33 in FIG. 2 is a distribution viewer, and 34
is a spark plug, and 35 is a battery.

Next, the content of control by the control unit 28 will be explained based on the flowchart shown in FIG. 3. The flowchart is roughly divided into a routine for cylinder discrimination and a routine for fuel calculation. Therefore, in the following explanation, each of these routines will be explained separately.

I. Cylinder Discrimination Routine (Steps 36-47) First, in step 36, the routine is initialized and the number of cylinders flag is set to 1. When this cylinder number flag is "1", it is all-cylinder operation, and when it is "0"
This means reduced cylinder operation.

Next, in step 37, the intake air temperature,
Data such as engine cooling water temperature, intake negative pressure, engine speed, and slot position are input.

Thereafter, based on the data input in step 37, steps 38 to 40 are sequentially determined to determine whether the engine operating state satisfies the conditions for reduced-cylinder operation. In other words, the cooling water temperature is at the set value.
The temperature is higher than T ₀ (for example, 60°C) (step 38), the engine speed is low than the set value N ₀ (for example, 200 rpm), and (step 3
9) If all of the following conditions are met: the vehicle is not in an accelerated state but is in a steady or decelerated state (step 40), the process proceeds to step 41.
Note that whether or not it is in the acceleration state is determined by calculating the amount of change in the slot position per unit time to obtain acceleration, and determining whether or not this acceleration is greater than the set acceleration.

From step 41 above, since the cylinder number flag is initialized to be 1 in step 37, the process first moves to step 42, where it is determined whether the intake negative pressure is greater than or equal to the set value _P4 . Ru. If the intake negative pressure is a low load below the set value _P4 , the process moves to step 43, where the number of cylinders flag is set to 0.

The transition to step 43 is when all the conditions for reduced-cylinder operation are satisfied, so in step 44 an output is made to indicate that reduced-cylinder operation (in the embodiment, 2-cylinder operation) is to be performed, that is, the solenoid 26 , 27 are demagnetized, resulting in reduced-cylinder operation in which the intake and exhaust valves 14 and 15 of the first and fourth cylinders are maintained in the closed state.

After this, fuel calculation processing is performed in steps 48 to 52, which will be described later, and the process returns to step 37. However, if the operating condition of the engine is the same as in the case described above, the same steps as described above are carried out. 41. Then, in step 41, since the cylinder number flag is set to 0 in step 43 as described above, the process moves to step 45, where the intake negative pressure is set to the set value _P2.
It is determined whether or not the value is larger than that. In other words, the intake negative pressure is different during reduced-cylinder operation and during full-cylinder operation even if the engine speed is the same, and therefore, the conditions for switching to full-cylinder operation during reduced-cylinder operation are different. The intake negative pressure P ₂ used during reduced-cylinder operation is used, and the intake negative pressure P ₄ , which is the condition for switching to reduced-cylinder operation during full-cylinder operation, is used during full-cylinder operation (P ₂ > _P4 ). This prevents frequent switching between reduced-cylinder operation and full-cylinder operation in response to intake negative pressure within a short period of time (hunting prevention).

Here, if the cooling water temperature is lower than the set value T ₀ ,
One of the following conditions: when the engine speed is higher than the set value N ₀ , when accelerating, when the intake negative pressure is greater than the set value P ₂ (during reduced cylinder operation) or P ₄ (during full cylinder operation) If it matches,
The process moves to step 46, where the cylinder number flag is set to 1, and then, in step 47, an output indicating that all-cylinder operation is to be performed is provided. That is, the solenoids 26 and 27 are deactivated, and the intake and exhaust valves 14 and 15 of all cylinders are opened and closed, resulting in an all-cylinder movement.

Fuel Calculation Routine (Steps 48 to 57) First, during cylinder reduction operation, the process moves from step 44 to step 48, where it is determined whether or not the engine is in a deceleration state. Note that whether or not this is the case is determined based on, for example, the throttle position and engine rotational speed.

If it is determined in step 48 that the engine is not in a deceleration state, the process moves to step 49, where a basic map for cylinder reduction operation consisting of a function of intake negative pressure and engine speed is selected, and the basic fuel injection amount is determined. It is determined. After that, in step 50, a pulse width corresponding to the basic fuel injection amount is calculated, and then
In step 51, the calculated pulse width is corrected based on the engine cooling water temperature and intake air temperature. Then, in step 52,
Fuel is injected from the fuel injection valve 10 with the corrected pulse width.

If it is determined in step 48 that the engine is in a deceleration state, the process proceeds to step 53, where it is determined whether the engine speed is greater than _N1 . This rotation speed N ₁ is determined by supplying a small amount of deceleration fuel or using normal fuel (in excess of this deceleration fuel), since the very low speed torque is small during cylinder reduction operation and engine stall is likely to occur. This is set as the boundary point for whether or not to supply (generally idle fuel), and if the rotation speed is less than _N1 , the process moves to step 49 described above.
Processing of steps 50, 51, and 52 is performed.
Further, if it is determined in step 53 that the rotational speed is equal to or higher than _N1 , the process moves to step 54.
The deceleration fuel for cylinder reduction operation is determined, and thereafter steps 50, 51, and 52 are performed.

On the other hand, during full-cylinder operation, the process moves from step 47 to step 55, and if it is not in a deceleration state, it moves to step 56, and if it is in a deceleration state, it moves to step 57.

In step 56, a basic map for all-cylinder operation consisting of intake negative pressure and engine speed is selected, and a basic fuel injection amount is determined. Also,
When the process moves to step 57, the deceleration fuel for all-cylinder operation is determined. and,
After step 56 or 57, steps 50, 51, and 52 described above are performed. Of course, the deceleration fuel for reduced-cylinder operation determined in step 54 is smaller than the deceleration fuel for full-cylinder operation determined in step 57.

Here, in FIG. 4, the region in which reduced-cylinder operation is required is indicated by α, the region in which full-cylinder operation is required is indicated by β, the region in which deceleration fuel is supplied during reduced-cylinder operation is indicated by γ, and the region in which reduced-cylinder operation is performed is indicated by γ. The region in which deceleration fuel supply is performed is indicated by δ. In FIG. 4, _N0 is the set engine speed at step 39, _N1 is the set engine speed at step 53, and point A is the boundary point of whether or not the deceleration state is in progress. This shows the throttle position. Further, in FIG. 4, the relationship between the determination of the fuel to be supplied and the ranges α to δ is that the range α is at step 49 and the range β is at step 49;
The region of .gamma. is determined in step 56, the region of .gamma. in step 54, and the region of .delta. in step 57.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

It can be applied not only to 4-cylinder engines but also to other multi-cylinder engines such as 6-cylinder engines, and the number of cylinders to be deactivated is not limited to half of the total number of cylinders, but can be set to an appropriate number (for example, 6 cylinders). In a cylinder engine, two or four cylinders can be stopped, etc.).

In order to configure a deactivated cylinder, valve drive control devices 24 and 25 are provided in the valve train mechanism, and the camshaft 18
The present invention is not limited to one that blocks the movement of the intake/exhaust valves 14 and 15; for example, a shutter valve may be provided in the intake passage corresponding to the cylinder to be deactivated to cut off the supply of air-fuel mixture to the cylinder to be deactivated. Good too. Furthermore, in the case where each cylinder is provided with a fuel supply device such as a fuel injection valve individually, the fuel supply from the fuel injection valve to the cylinder to be stopped may be cut off. Even in this case, the effect of reducing pumping loss due to not being supplied with intake air can be obtained.

The control unit 28 is an analog type,
It can be constructed by any digital computer.

A carburetor may be used as the fuel adjustment device, and in this case, the deceleration fuel can be adjusted by changing the diameter of the main jet or main air jet, for example.

The amount of deceleration fuel may not be set fixedly, but may be varied, for example, depending on the engine speed; in this case, a map may be selected for this purpose in step 57.

In step 50, instead of calculating the pulse width, especially during deceleration, the period of the pulse may be changed to adjust the amount of injected fuel.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
Since the appropriate amount of deceleration fuel for full cylinder operation and reduced cylinder operation can be obtained, it is possible to save fuel by not supplying excess deceleration fuel unnecessarily, and to move from deceleration operation to the next acceleration operation, etc. Good responsiveness during transition can be ensured.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is an overall system diagram showing one embodiment of the present invention. FIG. 3 is a flowchart showing an example of control contents of the present invention. FIG. 4 is a diagram showing area divisions for determining fuel to be supplied according to operating conditions. 1...Engine body, 8...Intake passage, 10...
...Fuel injection valve, 11...Slot valve, 14...
...Intake valve, 15...Exhaust valve, 24, 25...Valve drive control device, 28...Control unit.

Claims (1)

[Scope of Claims] 1. A cylinder reduction determining means for determining whether or not a cylinder reduction operation region is in which some cylinders are deactivated according to the operating state of the engine; and receiving an output from the cylinder reduction determination means. a cylinder number control means that is activated to cut off intake air supply to some of the cylinders and deactivate the some of the cylinders; a fuel adjustment device for supplying fuel to an intake passage of the engine; and a detection of a deceleration state. a deceleration detecting means for detecting deceleration, and receiving outputs from the deceleration detecting means and the cylinder reduction determining means to control the fuel adjustment device to supply a small amount of deceleration fuel to the operating cylinders during deceleration, and to A fuel control device for a cylinder number controlled engine, comprising: deceleration fuel control means for reducing the amount of fuel during reduced-cylinder operation than during full-cylinder operation.