JPH051367B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides an engine in which the cylinders are divided into a plurality of groups, and the operation of the cylinders of a predetermined specific group can be stopped. This invention relates to a divisional operation control device that suspends and restarts only a specific set of operations while continuing the operation of the other group.

[Conventional technology]

In general, an engine has better thermal efficiency when operated at high load than at low load. Therefore, when the engine load is low, the operation of a specific cylinder is stopped and the remaining cylinders are operated, resulting in A split-operation controlled engine has been developed that increases the load on the engine and improves overall thermal efficiency.

In such a split operation control type engine, the load state of the engine is detected, and depending on the magnitude of the load state, the operation of a specific cylinder is controlled to be stopped. Therefore, when the engine load increases as a result of an acceleration operation, a specific cylinder whose operation has been suspended until then will resume operation.

When the operation of a specific cylinder that has been suspended is restarted, or conversely, when the operation of a specific cylinder is suspended from the operating state of all cylinders, the engine operating state suddenly changes at that moment, and the intake pipe negative pressure and intake air Since values representative of the engine load, such as engine load, fluctuate, a hunting phenomenon may occur in which the operation of a specific cylinder is repeatedly restarted and stopped within a short period of time, which is controlled by the engine load.

The load fluctuations that cause such hunting can be broadly classified into two types. One is unstable behavior inside the engine system. For example, the intake air in the intake pipe exhibits temporary unstable behavior, and the detected value of the load detection means is different from the operating state of all cylinders and the resting state of a specific cylinder. This corresponds to a case where the switching reference value fluctuates in the vicinity, but in such a case, hunting can be prevented by providing hysteresis in the switching reference value.

[Problem to be solved by the invention]

Another cause is vehicle vibration due to a sudden change in the engine operating state. For example, this vehicle vibration may cause a change in the amount of driving operation by the driver, resulting in a large load fluctuation on the engine. This amount of variation is different from the load variation within the engine system,
Since the range of fluctuation is not constant, it may exceed the above-mentioned hysteresis range, resulting in hunting. As a countermeasure to this, it is possible to make the hysteresis width extremely large, but in that case, the load value that is the reference value for switching from the idle state of a specific cylinder to the operating state of all cylinders would be set quite high. , the shock at the time of switching becomes even larger, resulting in deterioration of acceleration drivability, ride comfort, and reduction in engine durability.

In addition, the load value that serves as the reference value for switching from all-cylinder operating state to specific cylinder inactive state is also set to a fairly low value, so the specific cylinder inactive period is shortened, resulting in the high efficiency inherent to split-operation controlled engines. That advantage is lost.

In view of these conventional problems, an object of the present invention is to prevent the hunting phenomenon without providing a large hysteresis in the switching reference value of the operating state, and regardless of the magnitude of load fluctuation at the time of switching. There is a particular thing.

[Means to solve the problem]

In order to achieve this object, the engine divided operation control device of the present invention divides the cylinders into a plurality of groups, as shown schematically in FIG. An engine split operation control device that enables engine split operation control, including engine load detection means for detecting engine load, and determining whether or not the engine load detected by the engine load detection means is smaller than a predetermined reference value. a determination means for suspending operation of only a specific set of cylinders when the determination means determines that the engine load is smaller than a reference value; When the load changes from a state smaller than the reference value to a state larger than the reference value, all-cylinder operation is immediately executed, and the engine load detected by the engine load detection means changes from a state larger than the reference value to a state larger than the reference value. It is characterized by comprising a delay means for delaying the start of execution of the operation suspension of the specific set of cylinders by the operation suspension means and continuing the operation state of all cylinders until a predetermined period of time has elapsed from the time when the cylinder changes to the small state. There is.

[Effect]

The engine load detection means detects the engine load, and the determination means determines whether the engine load detected by the engine load detection means is smaller than a predetermined reference value.
When the determination means determines that the engine load is smaller than the reference value, the operation suspension means suspends operation of only the specific set of cylinders.

Here, when the engine load detected by the engine load detection means changes from a state smaller than the reference value to a state larger than the reference value,
That is, when transitioning from a state in which the operation of only a specific set of cylinders is stopped to an all-cylinder operating state, the state is immediately shifted to an all-cylinder operating state, and on the other hand, the engine load detected by the engine load detection means is set to the above-mentioned standard. When the state changes from a state larger than the reference value to a state smaller than the reference value, that is, when there is a transition from an all-cylinder operating state to a state where only a specific set of cylinders is stopped, the operation of the specific set of cylinders is stopped by the above-mentioned operation stopping means. The start of execution is delayed by a predetermined period of time by the delay means.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an embodiment, in which two cylinders of a fuel injection four-cylinder engine are configured to be deactivated. Here, 30 is the engine body, 3
1 indicates the cylinder head, and each cylinder A~
D includes a combustion chamber 32, an intake valve 33, an intake port 34, an exhaust valve 35, and an exhaust port 36, respectively. Each intake port 34, intake manifold 3
It is connected to a surge tank (not shown) via 7,
Combustion air is drawn in from an intake pipe (not shown). An air flow sensor 20 is attached to the intake pipe to detect the amount of intake air. Further, fuel injection valves 60 are attached to the intake manifold 37 in correspondence with each intake port 34, respectively.

The intake valves 33 and exhaust valves 35 of the first cylinder A and the fourth cylinder D are constantly controlled to open and close by a valve mechanism (not shown) during engine operation. It can be operated at all times.
On the other hand, the intake valves 33 of the second cylinder B and the third cylinder C
The opening and closing of the exhaust valves 35 and 35 are also controlled by the valve mechanism, but the second cylinder B and the third cylinder C are operated by a valve lock device 52 to keep the intake valve 33 and the exhaust valve 35 closed as necessary. The valve lock device 52 is provided for the intake valve 33 and exhaust valve 35 of the second cylinder B and the intake valve 33 and exhaust valve 35 of the third cylinder C, respectively. Each valve lock device 52 is provided with a solenoid 51.
In the energized state, the intake valve 33 and the exhaust valve 35 are kept closed.

The solenoid 51 and the fuel injection valve 60 are controlled by the control circuit 40.
The control circuit 40 also controls an igniter (not shown) for igniting the engine, but this is not directly related to the present invention and will therefore be omitted from further explanation.

The control circuit 40 is constituted by a microcomputer and includes microprocessing units connected to each other by a bidirectional bus 46.
It includes a CPU 41, a read-only memory ROM 42, a random access memory RAM 43, an input circuit 44, and an output circuit 45. The output circuit 45 is
It has a drive circuit for energizing each solenoid 51 and fuel injection valve 60, and is connected to each solenoid 51 and fuel injection valve 60. Further, the input circuit 44 has a circuit for inputting signals from each sensor, and is connected to the cylinder discrimination sensor 11, the crank angle sensor 12, and the air flow sensor 20. Here, the cylinder discrimination sensor 11 and the crank angle sensor 12 are connected to the distributor 10.
By detecting the rotation of the distributor shaft 13, the cylinder discrimination sensor 11 detects the top dead center of the first cylinder A, and the crank angle sensor 12 detects the top dead center of the first cylinder A. Detects the signal every 30 degrees of rotation. Therefore, the crank angle sensor 12 constitutes an engine rotation speed sensor. Although not shown, the input circuit 44 is also connected to an intake air temperature sensor, a cooling water temperature sensor, a vehicle speed sensor, and the like.

The control circuit 40 is operated by a program stored in the ROM 42, receives signals from each sensor via the input circuit 44, processes them, determines the fuel injection amount or ignition timing, and outputs the output circuit 45. The fuel injection valve 60 or the igniter is controlled via the fuel injection valve 60 or the igniter.

In addition, the solenoid 51 which is characteristic in the present invention
The control is performed as shown in FIGS. 3A and 3B.

When the divided operation control routine shown in FIGS. 3A and 3B is started, first, in step 111, the engine rotation speed N and the intake air amount Q detected by the crank angle sensor 12 and the air flow sensor 20 are processed.
is taken in. Then, in step 112,
As a value representative of the engine load, the amount of intake air q per engine revolution is determined by q=Q/N.

Next, in steps 121 and 122, reference values Kl and Kh are determined when determining whether or not to suspend the operation of the second and third cylinders B and C. here,
Kl is the lower limit value when stopping operation, and Kh is the upper limit value when restarting operation. Reference value Kl,
Both Kh can be obtained from maps fN and gN as shown in Fig. 4 based on the engine speed.

In step 131, the vehicle speed data SPD is taken in, and in step 132, the vehicle speed SPD is
It will be judged whether the weight is 15Kg/h or more. If the vehicle speed is not 15 km/h or higher, a negative determination is made in step 132, and the process proceeds directly to step 1.
However, if the vehicle speed is 15 km/h or higher, an affirmative determination is made in step 132 and the process proceeds to step 1.
The process advances to step 33, where the flag FSPD is set to "1". Further, in step 134, it is determined whether the engine speed N is 500 rpm or less. If the engine speed N is not less than 500 rpm, a negative determination is made in step 134, and the process directly proceeds to step 136, but if the engine speed N is
If it is less than 500 rpm, an affirmative decision is made in step 134, and the process proceeds to step 135, where the flag FSPD is reset to "0". In other words, if the engine has been started and the engine speed has become higher than 500 rpm and the vehicle speed has exceeded 15 km/h as a result of the processing in steps 132 to 135, this state is determined by the setting of the flag FSPD. be remembered.

Next, in steps 136 to 139, it is determined whether or not to stop the operation of the second and third cylinders B and C. First, in steps 136 to 138, it is checked whether the engine cooling water temperature THW is in the stable operating range of 70°C or more and 110°C or less, whether the above-mentioned flag FSPD is set, and whether the engine speed is
It is determined whether or not the engine is in the low rotation range of 3000 rpm or less, and if any of the conditions is not satisfied, a negative determination is made in steps 136 to 138 and the process proceeds to step 127, where 2, The flag F2CYL, which stores the suspension of operation of No. 3 cylinders B and C, is reset to "0". However, when all the conditions in steps 136-138 are satisfied, affirmative decisions are made in all steps 136-138. Therefore, the next step 139
, idle switch LLS/W (not shown)
A determination is made as to whether or not it is turned on. The idle switch is a switch that is turned on when the throttle valve (not shown) is in the fully closed position,
If the throttle valve is now fully closed and the idle switch is on, and step 139 is affirmed, the process unconditionally advances to step 126, where the flag F2CYL mentioned above is set to "1".
shall be. However, if the throttle valve is not fully closed and the idle switch is off, a negative determination is made in step 139 and the process proceeds to step 123.

In steps 123 to 127, a final determination is made as to whether or not to stop the operation of the second and third cylinders B and C, based on the engine load. First, in step 123, it is determined whether or not the flag F2CYL is in the set state.
If CYL is not set, step 12
Proceeding to step 4, it is determined whether the intake air amount q per engine revolution is less than the reference value Kl. Conversely, if the flag F2CYL has already been set, the process proceeds to step 125. , it is determined whether the intake air amount q per engine revolution is equal to or greater than a reference value Kh. In this way, the reason why the reference values Kl and Kh are used depending on whether the flag F2CYL is in the set state is to provide hysteresis to the control and to adjust the amount of intake air q per engine revolution.
This is to prevent the hunting phenomenon from occurring when is near the reference value. Hunting prevention using this hysteresis has no effect on fluctuations in the intake air amount q that exceed the predetermined hysteresis range, but unlike the delay in stopping operation of a specific cylinder, which will be described later, the hunting prevention is effective when the engine is operating in a substantially steady state. The condition for stopping the operation of a specific cylinder may or may not be met when relatively small load fluctuations occur repeatedly, such as when the engine is stopped or when relatively small load fluctuations occur, such as intake pulsation in the intake pipe when switching between stopping operation of a specific cylinder and operating all cylinders. It is provided separately for the purpose of preventing repetition.

In step 124, if the amount of intake air q per engine revolution is less than the reference value Kl, in step 126 a flag F2CYL is set,
If in step 125 the intake air amount q per engine revolution is equal to or greater than the reference value Kh, then in step 127 the flag F2CYL is reset. If these conditions are not met, negative decisions are made in steps 124 and 125, and the flag F2CYL is maintained at its current state.

Next, in steps 141 to 143, the flag F
The solenoid 51 is energized depending on the state of 2CYL,
De-energization is determined and the solenoid 51 is controlled. That is, when the flag F2CYL is set to "1", the process finally proceeds to step 142, where the solenoid 51 is energized and the flag F2CYL is set to "1".
When CYL is reset and becomes “0”,
Proceeding to step 143, the solenoid 51 is de-energized.

As a result of controlling the energization of the solenoid 51 in this way, the idle switch is off, and
When other conditions are such that the operation of No. 2 and No. 3 cylinders B and C can be stopped, the amount of intake air q per engine revolution is equal to the reference value Kl, Kh.
When the amount is smaller, the solenoid 51 is energized, the operation of No. 2 and 3 cylinders B and C is stopped, and the intake air amount q per engine revolution is equal to the reference value Kl.
When it is larger than Kh, the solenoid 51 is de-energized and the 2nd and 3rd cylinders B and C are operated. Note that when the operation of the second and third cylinders B and C is stopped, fuel injection to the second and third cylinders B and C is also stopped.

By the way, in the present invention, step 151
156, in which a predetermined time delay is provided when the solenoid 51 is energized in step 142 after an affirmative determination is made in step 141. First, in step 151, it is determined whether or not a flag FC is set, which stores that the counter Nd has been preset in the set state. If the flag FC is not currently set, a negative determination is made in step 151 and the process proceeds to step 152, where the counter Nd is preset to a value corresponding to the delay time. Then, in step 153, a flag FC is set to remember that the counter Nd has been preset. After flag FC is set,
Step 151 is an affirmative decision. Now, step 15
2, 153 is not processed and proceeds directly to step 154, where counter Nd is decremented. In step 155, as a result of decrementing the counter Nd in step 154,
It is determined whether the preset value of the counter Nd has reached "0". If the preset value of the counter Nd has not reached "0" yet, a negative determination is made in step 155. However, when the preset value of the counter Nd reaches "0" after a predetermined period of time has passed since the counter Nd was preset, step 155 is executed. If the determination is affirmative, the process proceeds to step 142, where the solenoid 51 is energized. Note that in step 156, the counter Nd
If the flag F2CYL is reset before a predetermined time has elapsed since the flag F2CYL was preset, the flag FC is reset so that the next time the flag F2CYL is set, the counter Nd is preset again. ing.

Note that steps 111 and 112 in FIG.
The processing in steps 121 to 127 corresponds to the engine load detection means of the present invention, the processing in steps 141 and 142 corresponds to the operation suspension means in the present invention, The processing in steps 151 to 156 corresponds to the delay means of the present invention.

FIG. 5 is a time chart comparing the operation suspension control of a specific cylinder according to the present invention with that according to the conventional method, in which (A) shows the conventional case and (B) shows the case according to the present invention. As is clear from this figure, in the conventional control, when the operation of a specific cylinder is restarted and becomes 4-cylinder operation, a hunting phenomenon indicated by H occurs. On the other hand, in the case of the present invention shown in (b), the hunting phenomenon does not occur at all at the corresponding position, good acceleration driveability and ride comfort can be obtained, and the engine durability does not deteriorate. Nor.
As mentioned above, this is achieved by providing a predetermined time delay indicated by T when stopping the operation of a specific cylinder, that is, transitioning from 4-cylinder operation to 2-cylinder operation. This is because four-cylinder operation continues even if there is a large load change. Note that the transition from 4 cylinders to 2 cylinders is delayed by a predetermined period of time during deceleration, but even if deceleration is performed with 4 cylinders in operation, there will be no problem with deceleration performance as long as the load is reduced, and even in low load conditions, When the engine is stabilized, the engine shifts to two-cylinder operation after a predetermined period of time has elapsed, so the advantages of stopping a specific set of cylinders in the split-operation control engine are not lost.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. For example, the number of cylinders in the engine may be two or more, and the number of cylinder divisions may be three or more. Furthermore, the delay means may be configured by a hard circuit.

〔Effect of the invention〕

As described above, according to the present invention, a specific cylinder is not switched to the idle state again until a predetermined period of time has elapsed after switching to the all-cylinder operating state, so load fluctuations when switching the operating state are prevented. Regardless of the size of the engine, it is possible to prevent the hunting phenomenon in which operation of all cylinders and suspension of operation of a specific set of cylinders are repeated alternately.

Further, there is no need to provide a large hysteresis in the reference value for switching the operating state. In other words, there is no need to set the reference value for switching to the all-cylinder operating state to a very high value or to set the reference value for switching to the idle state for a specific cylinder to a very low value, so when accelerating,
The switch to all-cylinder operation is executed immediately when the standard value is exceeded, and good acceleration drivability, ride comfort, and engine durability are maintained, and on the low load side, the rest area of a specific cylinder is The advantage of the split operation control type engine, which is high efficiency due to the inactive state of specific cylinders, can be fully enjoyed.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims; FIG. 2 is a schematic configuration diagram of an embodiment of the present invention; FIGS. 3A and B are flowcharts showing program contents of a microcomputer forming the control circuit of FIG. 2; Figure 4 is a diagram showing a map for calculating reference values Kl and Kh, and Figure 5 is a diagram showing a map for calculating reference values Kl and Kh.
This is a time chart for explaining the operation of the present invention. 10...distributor, 11...cylinder discrimination sensor, 12...crank angle sensor, 20...
Air flow sensor, 30...Engine body, 31
...Cylinder head, A to D...Cylinder, B, C...
...Specific set of cylinders, 40...Control circuit.

Claims (1)

[Scope of Claims] 1. An engine divided operation control device that divides cylinders into a plurality of groups and makes it possible to suspend operation of a predetermined specific group of cylinders, comprising engine load detection means for detecting engine load. and determining means for determining whether or not the engine load detected by the engine load detection means is smaller than a predetermined reference value; and the determining means determines that the engine load is smaller than the reference value. and operation suspension means for suspending operation of only a specific set of cylinders; and when the engine load detected by the engine load detection means changes from a state smaller than the reference value to a state larger than the reference value,
All-cylinder operation is immediately executed, and the engine load detected by the engine load detection means changes from a state larger than the reference value to a state smaller than the reference value until a predetermined period of time elapses. An engine divided operation control device comprising: a delay means for delaying the start of execution of the operation suspension of a specific set of cylinders by the operation suspension means to continue the operating state of all cylinders.