JPS6036737A - Negative intake pressure detecting apparatus for engine capable of changing the number of cylinders to be operated - Google Patents

Abstract

PURPOSE:To enable to detect the negative intake pressure exactly, by calculating the mean value of the negative intake pressure detected by a negative intake pressure detecting means by a negative intake pressure averaging means as to the number of times determined by a means for determining the number of sampling times. CONSTITUTION:A means for judging whether the number of cylinders to be operated is to be reduced or not makes judgement on the basis of various data relating to the temperature of cooling water, negative intake pressure, engine speed, opening of a throttle valve, etc. according to the operational conditions of an engine and switches the operation mode of the engine to partial-cylinder operation by a means for controlling the number of cylinders to be operated when it is required from the result of the above judgement. At the same time, by controlling a means for determining the number of negative intake pressure sampling times, the number of sampling times is made greater than that at the time of full-cylinder operation of the engine. Further, a negative intake pressure averaging means calculates the mean value of negative pressure detected by a negative intake pressure detecting means as to the number of determined sampling times and mean value thus obtained is applied to a fuel injection quantity control means of an electronically controlled fuel injection means. With such as arrangement, it is enabled to detect the negative intake pressure exactly even at the time of partial-cylinder operation of the engine.

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 an intake negative pressure detection device for an engine with cylinder number control.

(Prior art) In recent years, there has been a desire for a significant improvement in fuel efficiency, especially in automobile engines.
As shown in Japanese Patent Application No. 38, an engine with cylinder number control has appeared in which the above-mentioned all-cylinder operation and reduced-cylinder operation can be appropriately switched and selected depending on the operating state of the engine. 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 fuel supply to some cylinders and increasing charging efficiency to other cylinders.

Such a cylinder number control engine is equipped with a cylinder number switching means for cutting the fuel supply to some cylinders and switching to cylinder reduction operation, and is equipped with a cylinder number switching means for switching to reduced cylinder operation by cutting the fuel supply to some cylinders, and is also equipped with a cylinder number switching means for switching to reduced cylinder operation by cutting the fuel supply to some cylinders. A cylinder reduction determining means is provided for detecting engine operating conditions such as negative pressure and engine temperature, determining whether or not cylinder reduction operation should be performed, and outputting the result of this determination to the cylinder number switching means.

Incidentally, the intake negative pressure of the engine is used in various ways as data for engine control.For example, it is of course used as data for determining whether or not to perform reduced-cylinder operation, but it is also used as data for electronically controlled fuel injection systems. It is also used as data for determining fuel injection amount. Since this intake negative pressure includes a pulsation component corresponding to the cycle of each cylinder, generally, the average value (moving average value) of a plurality of intake negative pressure values sampled sequentially a predetermined number of times at a predetermined time interval is This is used as data for engine control.

However, in engines with cylinder number control, there is a difference in the manner in which intake negative pressure is generated during all-cylinder operation and during reduced-cylinder operation, and it is especially difficult to accurately detect intake negative pressure during reduced-cylinder operation. Measures are required. In other words, in a 4-cylinder engine with 2 cylinders inactive, if intake pulsation occurs 10 times during full-cylinder operation within a certain predetermined period of time, the intake pulsation will occur 5 times during reduced-cylinder operation. , it is necessary to take some kind of countermeasure that takes into account the difference in the period of this pulsation.

(Object of the invention) The present invention was made in consideration of the following circumstances.
An object of the present invention is to provide an intake negative pressure detection device for an engine with cylinder number control, which can accurately detect intake negative pressure even during cylinder reduction operation.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention takes into consideration that the period of intake pulsation is longer during reduced-cylinder operation than during full-cylinder operation, and reduces the intake negative pressure during reduced-cylinder operation. The number of sampling times is greater than in the case of all-cylinder operation.

Specifically, as shown in FIG. 1, the cylinder reduction determining means determines whether cylinder reduction operation should be performed depending on the operating state, and the cylinder number control means is controlled based on the result of this determination. While switching to reduced-cylinder operation as appropriate, the sampling frequency determining means is also controlled so that the number of samplings of intake negative pressure is greater during reduced-cylinder operation than during full-cylinder operation. Then, the intake negative pressure averaging means calculates an intake negative pressure average value for the number of samplings determined by the sampling number determining means out of the intake negative pressure values detected by the intake negative pressure detecting means. Of course, this intake negative pressure average value is used for engine control, and is input to the fuel injection amount control means of an electronically controlled fuel injection device, for example, to determine the amount of fuel to be injected from the fuel injection valve. Used as actual data.

(Example) In Fig. 2, l is the engine body, and intake air is supplied to the combustion chamber 7 via the air cleaner 2, throttle chamber 4, intake manifold 5, and intake boat 6, and from the air cleaner 2 to the intake boat 6. The path between them constitutes an intake passage 8. Intake air flowing through this intake passage 8 is controlled by a throttle valve 11. Further, the exhaust gas from the fuel chamber 7 is discharged into the atmosphere from the exhaust boat 12 through the exhaust manifold 13 and the like.

The intake valve 14 that opens and closes the intake boat 6 and the exhaust valve 15 that opens and closes the exhaust boat 12 are opened and closed at predetermined timing by a valve operating mechanism. In this embodiment, this valve mechanism includes a crankshaft (not shown) in addition to a turn spring 16.17 that urges the intake/exhaust valve 14.15 in the valve closing direction.
The camshaft 18 is rotationally driven by a camshaft 18, a cam 19 provided on the camshaft, a rocker arm 20.21, and a tappet 22.23 that constitutes a swinging fulcrum for the rocker arm 20.21. In the embodiment, the engine main body l is for four cylinders, and the ignition order is set to 1-3-4-2, and during cylinder reduction operation, the first cylinder and the fourth cylinder are appropriately stopped, i.e., the fuel These are idle cylinders whose supply is cut off, and for this reason, valve drive control devices 24, 25 are attached to the tappets 22, 23 for the first and fourth cylinders.

The valve drive control devices 24, 25 are respectively switched and driven by solenoids 26, 27, and when the solenoids 26, 27 are demagnetized, the swinging fulcrum of the tappets 22, 23 relative to the rocker arms 2o, 21 is The rocker arms 20 and 21 swing in response to the rotation of the camshaft 18, and the rocker arms 20.
This is an all-cylinder operation in which exhaust valves 14 and 15 are opened and closed. Conversely, when the solenoids 26 and 27 are energized, the above-mentioned swing fulcrum can be displaced upward in the figure, and the camshaft 18 and the suction
The interlocking relationship with the antagonistic valves 14, 15 is cut off, and reduced-cylinder operation is performed with the intake and exhaust valves 14, 15 of the 1st and 4th cylinders maintaining their closed states.

The valve drive control devices 24 and 25 mentioned above are already well known, for example, as shown in Japanese Patent Application Laid-Open 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 selects and controls either full-cylinder operation or reduced-cylinder operation according to the operating state of the engine, and also selects and controls between full-cylinder operation and reduced-cylinder operation. This is to control the intake negative pressure to be detected (processed) differently during cylinder operation. Note that this control unit 28
The control system also controls the fuel injection amount, ignition timing, etc., but in the following description, description of parts that are not directly related to the present invention will be omitted.

The control unit 28 includes the opening degree of the throttle valve 11, the engine cooling water temperature as the engine temperature from the cooling water temperature sensor 29, and the intake negative pressure detected (sampled) by the intake negative pressure sensor 30 that detects the intake negative pressure. pressure,
The engine rotational speed from the ignition coil 31 and the ignition coil 31 are respectively inputted, while outputs are outputted from the control unit 28 to the solenoids 26 and 27.

In FIG. 2, 32 is a distributor, 33 is a spark plug, and 34 is a battery.

Next, regarding the contents of control by the control unit 28, first, the part for determining and switching between full-cylinder operation and reduced-cylinder operation will be explained based on the flowchart of FIG. 3.

First, in step 35, the number of cylinders flag is initialized to one. This cylinder number flag is "1"
When it is rOJ, it means full-cylinder operation, and when it is rOJ, it means reduced-cylinder operation.

Next, in step 36, the engine cooling water temperature, intake negative pressure, engine speed, and throttle valve opening are input.

Thereafter, based on the data input in step 36, it is sequentially determined in steps 37 to 39 whether the engine operating state satisfies the conditions for reduced-cylinder operation. That is, the cooling water temperature is the set value T.

(for example, eo”c) or higher (step 37).
, the engine speed is the set value N. (For example, 200Orpm
) or less (step 38), and it is determined that the vehicle is running at a steady or decelerating state, not in an acceleration state (step 3).
9) leads to step 40. Note that whether or not it is in an acceleration state is determined by differentiating the zero change in throttle opening with respect to time and calculating the acceleration α, which is the set value α. It is determined whether or not it is larger than the specified value.

From step 40 in -1-, the cylinder number flag is initialized to be 1 in step 36, so the process moves to step 41, where it is determined that the intake negative pressure is equal to or higher than the set value P4.
- It is determined whether or not. Then, if the intake negative pressure is a low load equal to or less than the set value P4, the process moves to step 42, where the cylinder number flag is set to 0.

When the process reaches step 42, all the conditions for cylinder reduction operation are satisfied, so from step 43 an output indicating that cylinder reduction operation (two cylinder operation in the embodiment) is to be performed is made, that is, solenoid 26. 27 is energized, and cylinder reduction operation is started in which the intake and exhaust valves 14 and 15 of the first and fourth cylinders are maintained in the closed state. And step 44
The program moves to O, where the fuel injection sleeve is determined, and the determined amount of fuel is injected from the fuel injection valve 10. It should be noted that the fuel injection process itself in step 44 is basically the same as in the case of a conventional electronically controlled fuel injection system, so a detailed explanation thereof will be omitted.

After this, the process returns to step 36, but if the operating state of the engine remains the same as described above, the process proceeds to step 40 as described above. Then, in step 40, since the cylinder number flag is set to O in step 42, the process moves to step 45, where it is determined whether the intake negative pressure is larger 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 P2 used is that during reduced-cylinder operation, and the intake negative pressure P2, which is the condition for switching to reduced-cylinder operation during full-cylinder operation, is
is for all-cylinder operation (P 2 > P
4). This prevents frequent switching between reduced-cylinder operation and full-cylinder operation due to suction negative pressure in a short period of time (hunting prevention).

Here, when the cooling water temperature is lower than the set value To, when the engine speed is higher than the set value No, or when accelerating, the intake negative pressure is lower than the set value Pt (during reduced cylinder operation) or P4 (during full cylinder operation). If either one of the following 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. That is, solenoid 26
．． 27 and demagnetize all cylinder intake and exhaust valves 14.15.
This is an all-cylinder operation in which the cylinders are opened and closed.

Next, we will explain the control details for detecting the intake negative pressure based on FIG. 4. The flowchart in FIG. , an interruption is made to the flowchart of FIG.

First, in step 48, the intake negative pressure detected by the intake negative pressure sensor 230 is inputted, and in step 49, the intake negative pressure detected by the intake negative pressure sensor 230 is inputted as P+.
It is stored as a closed file. Next, the process moves to step 50, where it is determined whether or not the cylinder reduction operation is being performed. This determination is made based on whether the cylinder number flag in step 40 in FIG. 3 is 1 or 0.

”=When it is determined in step 50 that the engine is in full-cylinder operation,
The process moves to step 51. In this step 51, all flags are initialized to O, and therefore, the process initially shifts from step 51 to step 52. In this step 52, the intake negative pressure PI stored in step 49 is sequentially stored a predetermined number of times n4 (for example, it is sequentially stored 16 times every 5 m5ec). Then, the process moves to step 53, and after setting all the flags in step 51 to 1, the process moves to step 54.

” - At step 54, the predetermined number of times n4 is set at step 52.
A plurality of sampled intake negative pressure values P.

The sum of 3 ~Pn4 is the number of samplings n4
A moving average, that is, an intake negative pressure average value FA is calculated. Then, proceed to step 55, and step 5
Among the predetermined number n of intake negative pressure values stored in 2.
Processing is performed to indicate that the oldest intake negative pressure value should be replaced with the newest intake negative pressure value, that is, data is rearranged. After this, in step 56, the cylinder reduction flag in step 57, which will be described later, is set to O.

After this, when the transition is made again to step 51 through steps 48 to 50 without transitioning to cylinder reduction operation, the all flag in step 51 is changed to step 5 as described above.
3 is 1, so in this case step 52.5
Step 51 to step 54.5 without going through step 3.
5.56.

On the other hand, if it is determined in step 50 that the cylinder reduction operation is being performed,
The process moves to step 57. In this step 57, since the cylinder reduction flag is initialized to 0, the process first moves from step 57 to steps 458, and then sequentially passes through steps 59, 60, 61, and 62. The flow of steps 58 to 62 is the same as steps 52, 53, 54, 55.
56, and the number of samplings of the intake negative pressure value in step 58, 12 (for example, sequentially performed 32 times every 5 m5ec), is greater than the number of samplings, n4, in step 52 at the time of all four rotations ( n2
〉n4) Differences.

Based on this difference in the number of sampling times, in step 60 corresponding to step 54, the sum of the intake negative pressure values of a predetermined number n2 is added to the predetermined number of sampling times n.
By dividing by 2, the intake negative pressure average value PA is calculated. Also,
Since this is a reduced-cylinder operation, in step 59 corresponding to step 53, the reduced-cylinder flag in step 57 is set to 1, and in step 62, which corresponds to step 56, all the flags in step 51 are set to 0.

After this, when the process goes through steps 48, 49, and 50 again to step 57 without changing to full-cylinder operation, the cylinder reduction flag in step 57 is set to 1 in step 59 as described above. Therefore, in this case, the process proceeds sequentially from step 57 to steps 60, 61, and 62 without passing through steps 58 and 59.

Here, steps 51, 52, 53, 56 and corresponding steps 57, 58, 59, 62 are provided because the intake negative pressure changes instantly and greatly when switching between full cylinder operation and reduced cylinder operation. Taking this into consideration, the intake negative pressure data to be sampled is completely replaced from that before switching to that after switching. That is, the intake negative pressure value is different during full-cylinder operation and during reduced-cylinder cartwheel rotation, even if the engine speed is the same, and therefore, the intake negative pressure value detected by the intake negative pressure sensor 30 during full-cylinder operation is The intake negative pressure value is not used as data for calculating the intake negative pressure average value during reduced-cylinder operation (the same applies when switching from reduced-cylinder operation to full-cylinder operation).

6. Note that the intake negative pressure average value FA in step 54 shown in FIG. 4 is used as the intake negative pressure value in step 41 shown in FIG. The intake negative pressure average value FA at step 60 shown in FIG. 4 is used as the intake negative pressure value. Further, as the intake negative pressure value as data required for the fuel injection process in step 44 shown in FIG. 3, the intake negative pressure average value FA in step 51 or 57 shown in FIG. 4 is used. In this fuel injection process, as in the past, the basic fuel injection amount is determined by a map that is a function of engine speed and intake negative pressure. It has been created separately.

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 half of the total number of cylinders 7. (For example, in a 6-cylinder engine, 2 cylinders or 4 cylinders may be stopped.)

■In order to configure the idle cylinder, a valve drive control device 24, 25 is installed in the valve train machine, and the camshaft 18 and intake/exhaust valve 14 are
．． 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. In addition, in the case where a fuel supply device such as a fuel injection valve is provided individually for each cylinder,
Fuel may be supplied to the cylinders to be deactivated, and in this case, intake air may be supplied to the cylinders to be deactivated, or intake air may not be supplied at all to the cylinders to be deactivated. can. However, it is preferable to cut the intake air supply to the cylinders to be stopped, which reduces the so-called pumping loss and further improves fuel efficiency.

■The control unit 28 can be configured by either an analog type or digital type computer.

(2) As for the number of sampling times of the intake negative pressure, the intake negative pressure can be detected more accurately as the number of sampling times increases, but the sampling number may be set to an appropriate number in consideration of responsiveness. Of course, in order to avoid torque fluctuations as much as possible during cylinder reduction operation, and to shorten the cycle of intake pulsation as much as possible to improve the responsiveness, for example, in a 4-cylinder engine, the ignition order is set to 1st cylinder and 3rd cylinder. , 4
If the number cylinder and number 2 cylinder are set as cylinder number 1 and number 2, the number of cylinders inactive, number 1 and number 4 (or cylinder 2 and cylinder 3) will be set as the inactive cylinders, and the total number of cylinders, the number of inactive cylinders, and the ignition order will be changed. It is desirable to take this into consideration.

(Effects of the Invention) As is clear from the above, the present invention increases the sampling frequency of the intake negative pressure during reduced-cylinder operation, in which the cycle of intake pulsation is longer than during full-cylinder operation, compared to when all cylinders are rotated. Since the number of cylinders is increased, it is possible to accurately detect the intake negative pressure even during cylinder reduction operation.As a result, various controls of the engine using the intake negative pressure as data can be performed with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is a 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. l...Engine body 8...Intake passage 14...Intake valve 15...Exhaust valve 24.25...Valve drive control device 26.27...Solenoid 28・Q...Control unit 30Φ...Fist intake negative pressure sensor 0

Claims (1)

[Claims] (1) A cylinder reduction determining means for determining whether or not the cylinder reduction turning range is where fuel supply to some cylinders is cut in accordance with 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 intake air and cuts fuel supply to some of the cylinders; an intake negative pressure detection means that detects the intake negative pressure of the engine; and an output from the intake negative pressure detection means; intake negative pressure averaging means for sampling the intake negative pressure a predetermined number of times and calculating an average of the plurality of sampled intake negative pressure values; An intake negative pressure detection device for an engine with cylinder number control, comprising: means for determining the number of sampling times during reduced-cylinder operation than during full-cylinder operation.