JPS6036736A - Engine designed to be capable of changing the number of cylinders to be operated - Google Patents

Abstract

PURPOSE:To prevent knocking of an engine which is designed to be capable of changing the number of cylinders to be operated, by providing a means for detecting the temperature of intake air, and making the engine operate with all of its cylinders when the temperature of intake air becomes higher than a prescribed value. CONSTITUTION:A sensor 30 for detecting the temperature of intake air is attached to an intake passage 8 of an engine 1 which is designed to be capable of changing the number of cylinders to be operated. A control unit 28 selects the number of cylinders to be operated according to various operational conditions of the engine and switches the operation mode of the engine to full-cylinder operation forcibly when the temperature of intake air becomes higher than a prescribed value. With such an arrangement, it is enabled to avoid partial-cylinder operation having high tendency to cause knocking.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an all-cylinder operation in which output is output from all cylinders and a reduced-cylinder operation in which output is output from only some cylinders, depending on the operating state of the engine. This invention relates to a cylinder number controlled engine that performs switching.

(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, Japanese Patent Application Laid-Open No. 57-338
As shown in the above publication, an engine with a controlled number of cylinders has appeared in which the above-mentioned full-cylinder operation and reduced-cylinder operation can be appropriately switched and selected depending on the operating state of the engine. That is,
For example, during high loads such as when starting or driving at high speed,
While fuel is supplied to all cylinders to generate output from all cylinders, at low loads such as when driving at constant speed or on a steady road, fuel supply to some cylinders is cut and output is output from all cylinders. Efforts are being made to save fuel by increasing charging efficiency.

Such a cylinder number control engine is equipped with a cylinder number switching means for cutting fuel supply to some cylinders and switching to cylinder reduction operation, and also has a cylinder number switching means for switching to cylinder reduction operation by cutting fuel supply to some cylinders, and also controls engine speed, throttle valve opening, intake negative pressure, The cylinder reduction determining means detects engine operating conditions such as engine temperature, determines whether or not cylinder reduction operation should be performed, and outputs the result of this determination to the cylinder number switching means.

However, in the conventional type, there is a problem that knocking may occur when accelerating during cylinder reduction operation, which is undesirable in terms of drivability. Of course, when accelerating, high output is required, so the engine is switched to all-cylinder operation, but there is some response delay in this switching, so some knocking may occur before all-cylinder operation is achieved. In addition, knocking is likely to occur even in the case of so-called slow acceleration, which does not lead to switching to all-cylinder operation.

When we investigated the causes mentioned above, we found that the engine intake air temperature has a large effect on knocking, especially in reduced-cylinder operation. In other words, the major factors related to knocking are engine load, compression ratio,
The intake air temperature, etc. is known, but during reduced-cylinder operation, the charging efficiency increases by -1 compared to all-cylinder operation, so the compression ratio for the cylinder to which fuel is supplied increases, so even if the intake air temperature remains the same, , Knocking is more likely to occur during reduced-cylinder operation than during full-cylinder operation.

(L'Objective of the Invention) The present invention has been made in consideration of the following circumstances, and provides an engine with cylinder number control that prevents knocking from occurring due to the influence of intake air temperature during cylinder reduction operation. The purpose is to provide.

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, when the intake air temperature of the engine exceeds a set value, all-cylinder operation is performed regardless of the presence or absence of acceleration. . That is,
A new element, intake air temperature, has been added to the engine operating state to be detected in order to determine whether to perform reduced-cylinder operation.

11 Specifically, as shown in Fig. 1, when the output (temperature) from the intake air temperature detection means is equal to or higher than the set value by monitoring the all-cylinder selection control means, all-cylinder operation is selected. The all-cylinder selection control means outputs a signal indicating that the all-cylinder selection control means is to select the number of cylinders to the cylinder number switching means.

(Example) In Fig. 2, l is the main body of the engine, and the intake air is
It is supplied to the combustion chamber 7 via the air cleaner 2, air flow chamber 3, throttle chamber 4, intake manifold 5, and intake boat 6, and the path from the air cleaner 2 to the intake boat 6 constitutes an intake passage 8. There is. The intake air flowing through the intake passage 8 is metered by an air flow sensor 9 and then mixed with fuel from a fuel injection valve 10 , 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 boat 6 and the exhaust valve 15 that opens and closes the exhaust port 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.
A camshaft 18 rotationally driven by a camshaft 18, a cam 19 provided on the camshaft, a rocker arm 20.21, and a tappet 2 constituting a swinging fulcrum of the rocker arm 20.21.
It is roughly composed of 2.23. In the embodiment, the engine body 1 is for 4 cylinders, and the ignition order is 1-3-4-2, and the 1st and 4th cylinders are stopped as appropriate, that is, the fuel supply is cut off. Therefore, tappet 2 for the 1st and 4th cylinders
2.23 is provided with a valve drive control device 24.25.

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 tappet 22, 23 relative to the rocker arm 20, 21 is The rocker arm 20.2 is located at a position displaced in the middle downward direction, and the rocker arm 20.2 swings in response to the rotation of the camshaft 18 to provide suction and air intake to all cylinders.
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 swinging fulcrum is displaced toward -H in the figure, and the interlocking relationship between the camshaft 18 and the intake/exhaust valves 14 and 15 is cut off. The cylinder reduction operation is performed while the intake and exhaust valves 14 and 15 of the first and fourth cylinders remain closed.

Note that the valve drive control device 24, 25 itself described above is
Since it is already well known, for example, as shown in Japanese Unexamined Patent Publication No. 52-56212, 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 and 27 to perform either full-cylinder operation or reduced-cylinder operation depending on the operating state of the engine. It controls the Note that this controller and troll unit 28 also controls the fuel injection amount, ignition timing, etc., but in the following explanation, only parts that are not directly related to the present invention, such as the ignition timing, will be explained. omitted.

-lz The control unit 28 includes the opening degree of the throttle valve 11, the engine coolant temperature as the engine temperature from the coolant temperature sensor 29, the intake air temperature from the intake air temperature sensor 30 provided in the intake passage 8, and the intake negative pressure. While the intake negative pressure detected by the sensor 31 and the engine rotation speed from the ignition coil 32 are input manually, the control unit 28 outputs the input signals from both solenoids 26 and 27.
Output for.

In FIG. 2, numeral 33 is a destroyer, numeral 34 is a spark plug, and numeral 35 is a battery.

Next, the details of control by the control unit 28 will be explained based on the flowchart shown in FIG.

First, in step 36, the flag is initialized to 1. When this flag is "1", it means full cylinder operation, and when it is "0", it means reduced cylinder operation.

Next, in step 37, each data of intake air temperature, engine cooling water temperature, intake negative pressure, engine speed, and throttle valve opening is input.

Thereafter, based on the data input in step 37, it is sequentially determined in steps 38 to 41 whether the engine operating state satisfies the conditions for reduced-cylinder operation. That is,
The intake air temperature is lower than the set value Fl (e.g. 80°C) (as determined in step 38), and the cooling water temperature is lower than the set value T.
. (e.g. 60°C or higher) (step 3)
9), the engine speed is the set value N. (For example, 2
500 rpm) or less (determination in step 40), and it is determined that the vehicle is running at steady or decelerated speed, not in an acceleration state (determination in step 41), the step 42.

Note that whether or not the vehicle is in the acceleration state is determined by differentiating the change θ in throttle opening with respect to time t to obtain acceleration α, and determining whether or not this acceleration α is larger than a set value α0.

” From Step 42, the flag is set to 1 in Step 37.
Since this is initialized, the process first moves to step 43, where it is determined whether the intake negative pressure is greater than or equal to the set value P4. Then, if the intake negative pressure is a low load equal to or less than the set value P4, the process moves to step 45, where the flag is set to 0.

The transition to step 45 is when all the conditions for cylinder reduction operation are satisfied, so in step 46 an output indicating that cylinder reduction operation (two cylinder operation in the embodiment) is to be performed is made, i.e. The solenoids 26 and 27 are energized, resulting in cylinder reduction operation in which the intake and D1 air valves 14 and 15 of the first and fourth cylinders are maintained in the closed state.

After this, the process returns to step 37, but if the operating state of the engine remains the same as described above, the process proceeds to step 42, as described above. Then, in step 42, as a result of the flag being set to O in step 45 as described above, the flag in step 42 is set to O.
Therefore, the process moves to step 44, 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 P2 used during reduced-cylinder operation is used, and the intake negative pressure P4, which is the condition for switching to reduced-cylinder operation during full-cylinder operation, is used during full-cylinder operation (
P2>P4). This prevents frequent switching between reduced-cylinder operation and full-cylinder operation in a short period of time depending on the intake negative pressure (hunting prevention).

Here, when the intake air temperature is higher than the set value Fo, and when the cooling water temperature is lower than the set value To, the engine speed is set (#
If any one of the following conditions is met: when accelerating, when the intake negative pressure is greater than the set value P2 (during reduced-cylinder operation) or P4 (during all-cylinder operation), step 47 After the flag is set to 1 at step 48, an output indicating that all-cylinder operation is to be performed is made. That is, the solenoids 26 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.

Although eleven 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.
The number of cylinders to be used is not necessarily half of the total number of cylinders, but can be any appropriate number (for example, in a six-cylinder engine, two or four cylinders are deactivated).

■To configure a 1L cylinder, a valve drive control device 24, 25 is installed in the valve mechanism, and the camshaft 18 and intake/exhaust valve 1 are
4.15, for example, holidays 1
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, if each cylinder is individually equipped with a fuel supply device such as a fuel injection valve, the fuel supply from the fuel injection valve to the cylinder that should be shut down is cut. In this case, intake air may be supplied to the cylinder to be deactivated, or intake air may not be supplied at all. However, it is preferable to also cut the intake air supply to the cylinders to be deactivated in order to reduce the so-called pumping loss and further improve fuel efficiency.

(2) The control unit 28 can be configured by either an analog or digital computer.

(Effects of the Invention) As is clear from the above description, the present invention performs all-cylinder operation, which is advantageous in avoiding knocking, when the intake air temperature becomes higher than the set value. It is possible to reliably prevent a situation where knocking occurs due to reduced-cylinder operation, which is desirable in terms of improving drivability and preventing engine damage.

[Brief explanation of drawings]

3 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 1 showing an example of control contents of the present invention.
・. ]...e...Fist engine body 8...Intake passage 14...Intake valve 15...Exhaust valve 24.25...Valve drive control device 26.27 Solenoid 28. ...φ control unit 30...φ・Intake temperature sensor 4

Claims (1)

[Claims] (+) Cylinder number switching means for switching from all-cylinder operation in which fuel is supplied to all cylinders to reduced-cylinder operation by cutting fuel supply to some cylinders. The number of cylinders is controlled to perform either full-cylinder operation or reduced-cylinder operation by controlling the cylinder number switching means according to the operating state of the engine. In the controlled engine, an intake air temperature detection means for detecting an intake air temperature, and an output from the intake air temperature detection means are received, and the intake air temperature is set to a set value.
an all-cylinder selection control means for controlling the cylinder number switching means to select all-cylinder operation when the temperature reaches a high temperature of