JPH0444091B2 - - 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 for a significant improvement in 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 it is possible to appropriately switch between full-cylinder operation and reduced-cylinder operation. In other words, when the load is high, such as when starting or driving at high speeds, fuel is supplied to all cylinders and output is output from all cylinders, while when the load is low, such as when driving at a constant speed or on a steady road, fuel is supplied to all cylinders. Fuel efficiency is achieved 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 switching means for cutting fuel supply to some cylinders and switching to reduced cylinder operation, and
Engine operating conditions such as engine speed, throttle valve opening, intake negative pressure, and engine temperature are detected to determine whether cylinder reduction operation should be performed, and the result of this determination is output to the reduction cylinder number switching means. It is equipped with a means for determining the number of reduced cylinders.

Incidentally, during acceleration, it is common practice to increase the amount of fuel by a predetermined amount, as shown in Japanese Patent Publication No. 47-38665. In other words, during acceleration, the throttle valve opens rapidly and the amount of intake air increases rapidly, but while this intake air flows relatively quickly into the combustion chamber, the fuel, which has a higher specific gravity compared to the air, flows into the intake air. Due to reasons such as the inability to completely follow the flow of air, during acceleration, accelerating fuel is supplied as additional fuel in anticipation of this delay.

By the way, Japanese Patent Application Laid-Open No. 57-200636 states that when accelerating when the throttle opening exceeds a predetermined value, the amount of fuel for acceleration is increased, assuming that the throttle opening is in full-cylinder operation, but when operating with reduced cylinders, the amount of fuel is increased. A vehicle has been disclosed in which the amount of acceleration fuel is not increased. In other words, even when driving on the same road surface at the same speed, the throttle opening is larger during reduced-cylinder operation than during full-cylinder operation, so when the throttle opening exceeds a predetermined value, the acceleration fuel is If the amount is constantly increased, there will be many chances that the amount of acceleration fuel will be increased during cylinder reduction operation even though there is no original acceleration request, so this is an attempt to prevent such a situation.

However, with the engine described in the above-mentioned Japanese Patent Application Laid-Open No. 57-200636, it is difficult to sufficiently satisfy the acceleration performance during cylinder reduction operation, and some kind of countermeasure is desired in this respect.

(Object of the Invention) Therefore, an object of the present invention is to provide a fuel control device for an engine with a controlled number of cylinders that can sufficiently satisfy acceleration performance not only during full-cylinder operation but also during reduced-cylinder operation. It is about providing.

(Structure of the Invention) In order to achieve the above object, the present invention has the following structure. That is, as shown in FIG. 1, there is provided a cylinder reduction determining means for determining whether or not a cylinder reduction operation region is in which some cylinders are deactivated depending on the operating state of the engine; and an output from the cylinder reduction determination means. a cylinder number control means that is activated in response to the engine's engine and cuts off intake air supply to some of the cylinders to deactivate the some of the cylinders; a fuel adjustment device for supplying fuel to an intake passage of the engine; a first acceleration determining means that receives an output from the cylinder determining means and determines that acceleration is occurring when a change in throttle opening is larger than a predetermined first acceleration determining level during full cylinder operation; and the reduced cylinder determining means. A second controller that receives an output from the controller and determines that acceleration is occurring when the change in throttle opening is larger than a second acceleration determination level that is set larger than the first acceleration determination level during cylinder reduction operation.
acceleration determining means; receiving outputs from the first acceleration determining means and the second acceleration determining means; controlling the fuel adjustment device and the cylinder number control means; The present invention is configured to include an acceleration fuel control means for supplying increased fuel for acceleration in a state of all-cylinder operation when it is determined that the vehicle is accelerating.

(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. The path up to the port 6 constitutes an intake passage 8. Fuel from a fuel injection valve 10 is mixed with the intake air flowing through the intake passage 8, and the amount of intake air is controlled by a throttle valve 11. Further, the exhaust gas from the fuel chamber 7 is discharged into the atmosphere through the exhaust port 12, through the exhaust manifold 13, etc.

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. are the cylinders to be cut. Therefore, for the tappets 22, 23 for the 1st and 4th cylinders, the valve drive control devices 24, 2
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,
No. 15 performs cylinder reduction operation while maintaining the valve closed state.

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. 52-5621, 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 solenoids 26, 27 to perform either full-cylinder operation or reduced-cylinder operation depending on the operating state of the engine. Of course, it also controls 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. .

The control unit 28 receives information about the opening 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, 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 air negative pressure sensor 31, and the ignition coil 32.
The engine rotational speeds from the control unit 28 are input to the control unit 28 and output to the solenoids 26, 27 and the fuel injection valve 10, respectively.

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 flowcharts shown in FIGS. The case is shown in which no acceleration fuel is supplied (during sudden acceleration that requires acceleration fuel, the engine shifts to all-cylinder operation). The above flowchart is roughly divided into a routine for cylinder discrimination, a routine for fuel calculation, and a routine for acceleration detection, so the following explanation will not be divided into each of these routines. I decide to go.

Cylinder Discrimination Routine (Steps 36-47) First, the routine is initialized in step 36, where the cylinder number flag is set to 1, the accelerator flag is set to 0, and the read value of the throttle opening is cleared. This cylinder number flag is
When it is "1", it means all-cylinder operation, and when it is "0", it means reduced-cylinder operation. Also, when the accelerator flag is "1", it means acceleration (sudden acceleration to switch to all-cylinder operation). time), and when it is "0", it indicates that it is not the time of acceleration.

Next, in step 37, the intake air temperature, engine cooling water temperature, intake negative pressure, engine speed,
Each data regarding throttle valve opening is input.

Thereafter, based on the data input in step 37, it is sequentially determined in steps 38 to 40 whether or not the engine operating state satisfies the conditions for reduced-cylinder operation. That is, the cooling water temperature is higher than the set value T ₀ (for example, 60°C) (step 38),
Engine speed is set value N ₀ (e.g. 2000rpm)
The vehicle is running at a low speed below (step 39), and is not in an acceleration state but is running at steady or decelerating speed (step 39).
40), if all the conditions are met,
Move to step 41. Note that whether or not the vehicle is in an acceleration state is determined by determining whether the accelerator flag is 1 or 0, and changing the accelerator flag is
This is done in the flowchart of FIG. 4, which will be described later.

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 cylinder number flag is set to 0.

The transition to step 43 above is when all conditions for cylinder reduction operation are satisfied.
In step 44, an output indicating that cylinder reduction operation (two cylinder operation in the embodiment) is to be performed is made, that is, the solenoids 26 and 27 are energized, and the intake and exhaust valves 14 and 15 of the first and fourth cylinders are closed. This results in cylinder reduction operation where the valve remains in the valve 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. Move to 41. Then, in step 41, since the cylinder number flag is set to 0 in step 43 as described above, the cylinder number flag in step 41 is converted to 0.
The process moves to step 45, where it is determined whether the intake negative pressure is greater than the set value _P2 . 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 is that during reduced-cylinder operation, 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 ,
When the engine speed is higher than the set value N ₀ , when accelerating (the accelerator flag in step 40 is 1)
), the intake negative pressure is the set value P ₂ (during cylinder reduction operation)
Or if it is larger than P ₄ (when operating on all cylinders),
If any one of the conditions is met, 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 made. i.e. solenoid 2
6 and 27 are demagnetized, and all-cylinder operation is performed in which the intake and exhaust valves 14 and 15 of all cylinders are opened and closed.

Fuel Calculation Routine (Steps 48-52) First, in step 48, the basic fuel injection amount τ is calculated from the engine speed and intake negative pressure. Of course, in this step 48, the above basic fuel is selected from the map for reduced cylinder operation or the map for full cylinder operation, depending on the output from steps 44 and 47 for reduced cylinder operation or full cylinder operation. This is to calculate the injection amount τ.

Next, in step 49, the basic fuel injection amount τ is multiplied by a correction coefficient C ₁ based on the cooling water temperature to correct the fuel injection amount (corrected fuel injection amount τ ₁ ). For the corrected fuel injection amount τ ₁ obtained by this correction, in step 50,
The corrected fuel injection amount τ ₂ is obtained by multiplying by a correction coefficient C ₂ based on the intake air temperature.

After this, the process moves to step 51, and when accelerating when the accelerator flag is 1, the process moves to step 52.
Then, the corrected fuel injection amount τ ₂ is multiplied by the acceleration-based correction coefficient C ₃ to calculate the corrected fuel injection amount τ ₃ . Then, in step 53, a signal based on this corrected fuel injection amount τ ₃ is output to the fuel injection valve 10. Also, step
If it is determined in step 51 that it is not the time of acceleration (the accelerator flag is 0), the process moves to step 53 without performing the fuel injection amount correction based on the acceleration in step 52, and the corrected fuel injection amount τ ₂ in step 50 is used. A signal based on this is output to the fuel injection valve 10.

Acceleration detection routine (Fig. 4) The flowchart shown in Fig. 4 interrupts the flowchart shown in Fig. 3 at predetermined time intervals.First, in step 54, the throttle valve is opened. The throttle valve opening degree is input as data at each predetermined time period, and in step 55, a predetermined number n of throttle valve opening degrees are sequentially stored as values for each predetermined time period.

Next, in step 56, it is determined whether the cylinder number flag is 0 or 1, and if it is 1, which is during all-cylinder operation, the process moves to step 57. In this step 57, a comparison level A of acceleration during all-cylinder operation is set. Further, when the number of cylinders flag in the step 56 is 0 during the cylinder reduction operation, the process moves from step 56 to step 58, and in this step 58, a comparison level A of acceleration during the cylinder reduction operation is set.

The processing in steps 57 and 58 above is performed because even with the same change in throttle opening, the level of acceleration is greater during full-cylinder operation than during reduced-cylinder operation. This is to make the comparison level of acceleration, which is a set value for determination, correspond to reduced-cylinder operation or full-cylinder operation.
For the reasons mentioned above, the comparison level during cylinder reduction operation is higher than the comparison level during full cylinder operation, and as a result, in order to obtain acceleration at the predetermined acceleration level that is the set value above, This means that a larger change in throttle opening is required than when operating with all cylinders.

From step 57 or 58, the process moves to step 59, where the change in throttle opening per predetermined time, that is, the level of acceleration (TV ₁
-TVn) is calculated and the calculated acceleration level B is applied to the comparison level A in step 60.
It is determined whether or not the value is larger than that. When the acceleration level B is larger than the comparison level A, that is, when it is determined that the acceleration state is present, the process moves to step 61 and the accelerator flag is set to 1.
Further, when it is determined that the acceleration level B is lower than the comparison level A and is in steady state or deceleration operation, the process moves to step 62 and the accelerator flag is set to 0. Of course, this step 61 or 62
The accelerator flag at step 40 is used for the determination at step 40 or step 51, respectively.

After this, proceed to step 63 and proceed to step 63.
The oldest throttle opening value stored in step 55 is changed to the newest throttle opening value, and the data is rearranged.

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
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 the fact that intake air is not supplied 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 amount of acceleration fuel can be increased by changing the diameter of the main jet or main air jet, for example.

During cylinder reduction operation, the acceleration fuel may be increased without being reduced to zero.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
When acceleration is determined during both reduced-cylinder operation and full-cylinder operation, acceleration fuel is supplied in the state of all-cylinder operation, so not only during all-cylinder operation but also during reduced-cylinder operation. Acceleration performance can be fully satisfied.

In addition, the acceleration judgment level according to the change in throttle opening is set higher during reduced-cylinder operation than during full-cylinder operation, so even though no acceleration is requested during reduced-cylinder operation, all cylinders are This also prevents a situation in which the amount of acceleration fuel is increased when the vehicle starts driving.

[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 and FIG. 4 are flowcharts showing an example of control contents of the present invention. 1...Engine body, 8...Intake passage, 10...
...Fuel injection valve, 11...Throttle 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 the intake air supply to some of the cylinders and deactivate the some of the cylinders; a fuel adjustment device for supplying fuel to the intake passage of the engine; and the cylinder reduction determination means. a first acceleration determining means that receives an output from the cylinder and determines that the throttle opening is accelerating when the change in throttle opening is larger than a predetermined first acceleration determination level during full cylinder operation; and an output from the reduced cylinder determining means. A second control unit that determines that acceleration is occurring when the change in throttle opening is greater than a second acceleration determination level that is set larger than the first acceleration determination level during cylinder reduction operation.
acceleration determining means; receiving outputs from the first acceleration determining means and the second acceleration determining means; controlling the fuel adjustment device and the cylinder number control means; 1. A fuel control device for an engine with a controlled number of cylinders, comprising: acceleration fuel control means for supplying increased fuel for acceleration in a state of all-cylinder operation when it is determined that acceleration is occurring.