JPH0783083A - Control device of variable cylinder engine - Google Patents

Abstract

PURPOSE:To eliminate restriction of decrease of the number of working cylinders more than required and to increase a fuel consumption reducing effect by way of partial cylinder operation by prohibiting variation of the number of the working cylinders until throttle opening becomes lower than a set value at the time when vehicle speed is lower than a set value. CONSTITUTION:An engine main body 1 has a large number of cylinders respectively provided on plural cylinder banks 1A, 1B. An intake port of each of the cylinders is respectively installed on a common intake pipe 4 through an intake branch pipe 3, and simultaneously, on each of them, a fuel injection valve 3a is respectively provided. Furthermore, on the intake pipe 4, a throttle valve 6 is provided. An ECU 30 to respectively control the fuel injection valves 3a and the throttle valve 6 controls the number of working cylinders. In this case, at the ECU 30, vehicle speed by engine speed and throttle opening by a sensor 6a and each set value are compared with each other. Consequently, at the time when the vehicle speed is lower than the set value, until the time when the throttle opening becomes lower than the set value, variation of the number of the working cylinders is prohibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable cylinder engine that suspends the operation of some cylinders depending on the engine operating condition.

[0002]

2. Description of the Related Art A variable cylinder engine is generally known in which the fuel consumption rate of the engine as a whole is improved by stopping the operation of some cylinders when the engine is partially loaded to reduce the number of operating cylinders. . In a normal engine, in partial load operation, the throttle valve narrows the intake passage in order to reduce the intake air amount of the entire engine, and the negative pressure in the intake pipe downstream of the throttle valve increases. For this reason, pumping loss at the time of sucking air into the engine combustion chamber increases. On the other hand, in the variable cylinder engine, operation of some cylinders is suspended during low load operation, and operation is performed only in the remaining cylinders. Under the same load condition, it is necessary to increase the intake amount according to the decrease of the operating cylinders and increase the output per operating cylinder when the cylinders are deactivated, as compared with the normal all-cylinder operation.
Therefore, in the variable cylinder engine, the throttle in the intake passage is less than that in the all-cylinder operation under the same load condition when the cylinder is inactive.
It will be operated in a state where the negative pressure of the intake pipe is small. Therefore, pumping loss at the time of partial load is reduced and the fuel consumption rate of the engine as a whole is improved. An example of the variable cylinder engine is described in JP-A-57-157033. According to the same publication, in order to prevent a rattling at the time of starting acceleration, when the starting state is detected, all cylinders are forcibly operated, and then, in order to prevent a switching shock, a transition from an all cylinders operating region to a partial cylinders operating region is made. It has been proposed to perform partial cylinder operation when the throttle is fully closed or when the throttle is fully closed.

[0003]

By the way, the original purpose of making the variable cylinders is to improve the fuel consumption based on the above-mentioned principle. Therefore, it is desirable to expand the operating range of the partial cylinders as much as possible. Therefore, even if the driver does not request acceleration even at the time of starting, it should be possible to operate in a partial cylinder. However, the above-mentioned JP-A-57-157 is used.
According to Japanese Patent Publication No. 033, when the start is detected regardless of the running state after the start, all cylinders are forcibly operated, so that the fuel consumption reduction effect is reduced. In view of the above problems, it is an object of the present invention to eliminate an unnecessarily limited decrease in the number of operating cylinders of a variable cylinder engine, and to increase the range of fuel consumption reduction effect by partial cylinder operation.

[0004]

According to the present invention, in a control unit for a variable cylinder engine for an automobile, which controls the number of operating cylinders of an engine in accordance with an engine operating state, vehicle speed detection for detecting the speed of a vehicle. Means, a calculating means for comparing and calculating the vehicle speed detected by the vehicle speed detecting means and a preset predetermined value, and a throttle opening degree detecting means for detecting the opening degree of a throttle valve arranged in the engine intake passage. Means and a calculation means for comparing and calculating the opening of the throttle valve detected by the throttle opening detection means and a predetermined value set in advance, and the speed of the vehicle is equal to or less than a predetermined value set in advance. In this case, there is provided a control device for a variable cylinder engine, which prohibits changing the number of operating cylinders until the throttle opening becomes equal to or less than a preset predetermined value. Further, the predetermined value of the throttle opening degree that prohibits the change of the number of operating cylinders can be made variable according to the vehicle speed.

[0005]

When the vehicle speed is equal to or lower than the predetermined value, the change of the number of operating cylinders is prohibited until the throttle opening is equal to or lower than the predetermined value. When the throttle opening is equal to or less than the predetermined value and the situation does not require acceleration, the number of operating cylinders can be changed and the change of the number of operating cylinders is not unnecessarily limited.

[0006]

1 is a general view showing an embodiment in which the present invention is applied to a V-type 8-cylinder variable cylinder engine. In FIG. 1, reference numeral 1 denotes an engine body. In the embodiment according to the present invention, the engine 1 has two cylinder banks 1A and 1B, and the bank A has the second, fourth, sixth, and sixth cylinders from the front end side to the rear end (output shaft end) side. Eight cylinders are arranged in the bank B, and first, third, fifth, and seventh cylinders are arranged in the bank B from the front end side to the rear end side of the engine. The intake ports of the respective cylinders are connected to a common intake pipe 4 via an intake branch pipe 3, respectively. Further, each intake branch pipe 3 is provided with a fuel injection valve 3a for injecting fuel into the intake port of each cylinder, and the intake pipe 4 is further provided with a manipulated variable of an accelerator pedal (not shown) of the driver. A throttle valve 6 that opens and closes in response to the throttle valve 6 and a throttle opening sensor 6a that generates an output voltage signal corresponding to the opening of the throttle valve 6, and an intake pipe upstream of the throttle valve 6 that outputs an output corresponding to the engine intake air amount. An air flow meter 8 that generates a voltage signal is arranged. Reference numeral 5 in the drawing denotes a throttle bypass passage connecting the upstream and downstream intake passages of the throttle valve 6. A bypass valve 7 that is opened and closed by an actuator 71 is provided in the bypass passage 5. In the embodiment according to the present invention, a step motor is used as the actuator 71, and the bypass valve 7 is opened / closed by an operation amount according to a drive signal from an electronic control unit (ECU) 30 described later.

Further, in the embodiment according to the present invention,
Exhaust ports of 8, 3, and 5 cylinders are independent exhaust pipes
12, 18, 13, 15 are individually connected to the
The 4th and 6th cylinders and the 1st and 7th cylinders have a common exhaust pipe,
They are connected to 14 and 11, respectively. The structure of this exhaust pipe is
Considering the combination of operating cylinders during partial cylinder operation described later
Has been decided. Each exhaust pipe 11, 12, 13, 14,
In 15 and 18, the oxygen concentration in the exhaust gas is detected and the exhaust air-fuel ratio is detected.
0 when the ratio is on the lean side with respect to the theoretical air-fuel ratio.
A voltage (lean voltage) of about 1 volt and a rich signal
When it is on the (rich) side, the voltage (rich
Oxygen concentration sensor (O ₂Sensor) 3
1 is arranged for each exhaust pipe. Furthermore, each exhaust
O of the tube₂On the downstream side of the sensor 31, HC, CO in exhaust gas,
NO_XIs a three-way catalyst 21 that can purify the three components of
They are arranged respectively. In the embodiment according to the present invention,
The output shaft of engine 1 is connected to automatic transmission 23,
Detects the rotation speed of the output shaft (not shown) of the automatic transmission 23
A rotation speed sensor 32 is provided.

Reference numeral 30 in the figure denotes an electronic control unit (ECU) for controlling the engine 1. ECU30 is R
It is configured as a digital computer including an OM (read only memory), a RAM (random access memory), a CPU (central processing unit), an input port, an output port, etc., and in the embodiment according to the present invention, fuel injection amount control of the engine 1, In addition to performing basic control such as ignition timing control, the operating cylinder number control means according to claim 1, a comparison calculation means for comparing and calculating whether or not the vehicle speed is larger than a predetermined value set in advance,
It acts as a comparison calculation means for comparing and calculating whether or not the throttle opening is larger than a predetermined value set in advance.

The input port of the ECU 30 has an air flow meter 8, an output shaft rotation speed sensor 32 of the automatic transmission, and O _{2 of} each.
Signals from the sensor 31 and the throttle opening sensor 6a are analog / digital converters (A / D converters) not shown.
In addition to being input via the engine, signals representing the engine cooling water temperature and the engine speed of the engine 1 are respectively input from a cooling water temperature sensor and an engine speed sensor, not shown. The output port of the ECU 30 is connected to the step motor 71 of the bypass valve to supply a drive pulse to the step motor to control the drive of the bypass valve 7, and to the fuel injection valve 3a and the ignition plug 33 of each cylinder. They are connected and perform fuel injection control and ignition timing control for each cylinder.

Next, the control of the number of operating cylinders of the variable cylinder engine 1 according to the embodiment of the present invention will be described with reference to FIGS. 2 and 3. In the embodiment according to the present invention, the ECU 30 switches the number of operating cylinders according to the operating load of the engine 1 and the traveling speed of the vehicle. FIG. 2 is a map showing an example of the relationship between the number of operating cylinders of the engine 1 and the load state. FIG. 2 shows only the case where the number of operating cylinders is switched among three, that is, four cylinders, six cylinders, and all eight cylinders in order to avoid complication, but actually, in the middle five cylinders and seven cylinders. Including the number of operating cylinders, a total of five operating cylinder number operations are possible.

The vertical axis of FIG. 2 represents the value Q / N obtained by dividing the engine intake air amount Q detected by the air flow meter 8 by the engine speed N, that is, the intake air amount per engine revolution. Q / N is used as a parameter representing the engine load. The horizontal axis of FIG. 2 represents the automatic transmission output rotation speed NA detected by the sensor 32 and is used as a parameter representing the vehicle speed. As shown in FIG. 2, in the embodiment according to the present invention, the number of operating cylinders is reduced as the vehicle speed NA is higher in the region where the engine load Q / N is low. As described above, in the variable cylinder engine, the output per operating cylinder can be increased as the number of operating cylinders is decreased. Therefore, when the load is low, the smaller the number of operating cylinders, the greater the effect of improving the fuel consumption rate. However, the pulsation of the output torque increases as the number of operating cylinders decreases, and this pulsation of torque appears as greater vibration as the vehicle speed (engine speed) is lower. It is not preferable in terms of operation to reduce the amount. Therefore, in the embodiment according to the present invention, the number of operating cylinders is increased as the vehicle traveling speed is lower during low load operation to prevent deterioration of drivability. In the present embodiment, the horizontal axis of FIG. 2 is the automatic transmission output rotation speed NA detected by the sensor 32, but may be the engine rotation speed N.

As will be described later, in the embodiment of the present invention, the opening degree of the throttle bypass valve 7 is increased as the number of operating cylinders is decreased to increase the intake air amount Q of the entire engine. Therefore, for example, in the case where Q / N is reduced in FIG. 2 and the number of operating cylinders needs to be reduced, the intake air amount is increased as the number of operating cylinders is reduced after switching, so that Q / There is a possibility that N may increase and enter the operating cylinder number increase region again, and the operating cylinder number may increase. Therefore, the judgment value for switching the number of operating cylinders is provided with hysteresis as shown by a solid line and a dotted line in FIG. 2 to prevent hunting of the switching operation. The solid line in FIG. 2 indicates the switching determination line on the operating cylinder number increasing side, and the dotted line indicates the switching determination line on the operating cylinder number decreasing side.

Next, FIG. 3 shows an example of a combination of operating cylinders during partial cylinder operation. FIG. 3 shows a combination of operating cylinders during partial cylinder operation of four cylinders, five cylinders, six cylinders, and seven cylinders, and the cylinder arrangement is the same as that in FIG. (That is, the upper side represents the bank 1A, and the circles in the figure indicate the second, fourth, and
Represents 6 and 8 cylinders. The lower side represents the bank 1B, and the circles in the figure represent the first, third, fifth, and seventh cylinders from the left side. ) Also, in the figure, the cylinders indicated by ● are operating cylinders, and the cylinders indicated by ○ are inactive cylinders. In the embodiment according to the present invention, a plurality of combination patterns of operating cylinders are set according to the number of operating cylinders. Naturally, combinations of operating cylinders during partial cylinder operation are possible other than those shown in FIG. 3, but the embodiment according to the present invention adopts the combination pattern as shown in FIG. 3 in consideration of the following conditions. .

First, since the deactivated cylinder does not generate torque during the partial cylinder operation, the engine output torque falls at each time corresponding to the decommission stroke of the deactivated cylinder during one revolution cycle of the engine. Therefore, in order to avoid a large torque pulsation, it is preferable to consider the ignition sequence so that the torque drop due to the idle cylinders is dispersed as much as possible during one operating cycle of the engine. In the embodiment according to the present invention, engine ignition is performed as follows: 1st → 8th → 4th → 3rd →
Since the sixth cylinder, the fifth cylinder, the seventh cylinder, and the second cylinder are performed in this order, the combination of the deactivated cylinders is set so that the deactivated cylinders are dispersed as much as possible in this ignition order. FIG. 4 shows the positions of the idle cylinders in the engine ignition sequence in the operating cylinder combination pattern in the case of the 5-cylinder operation. As shown in FIG. 4, a deactivated cylinder in pattern 1 (first, third, and seventh cylinders → shown in FIG. 4) and a deactivated cylinder in pattern 2 (second, fourth, and sixth cylinders → FIG. 4) during operation of five cylinders. (Shown above) are also considered to be evenly distributed. Figure 4
Although only the case of 5-cylinder operation is shown in Fig. 4, the same consideration is given to the combination pattern in other operating cylinder numbers.

Further, in the embodiment according to the present invention, a combination pattern of a plurality of operating cylinders is provided for each number of operating cylinders, as shown in FIG. 3, for the reason described below. That is, in the embodiment according to the present invention, air is supplied to the idle cylinders even during the partial cylinder operation, but since combustion does not occur in the cylinders, this air is discharged to the exhaust pipe at a low temperature and the three-way catalyst 21 is discharged. Will pass through. For this reason, if the partial cylinder operation continues, the temperature of the deactivated cylinder will decrease, which may affect the durability of each part due to non-uniform engine temperature. The original catalyst 21 is cooled, and when the operation of the idle cylinder is restarted next time, the three-way catalyst is below the activation temperature, and there is a possibility that exhaust purification will not be performed on this catalyst until the temperature rises. . Therefore, in the embodiment according to the present invention, a plurality of patterns of combinations of the number of operating cylinders during the partial cylinder operation are provided, and the combination pattern of the operating cylinders is switched at predetermined time intervals during the partial cylinder operation, so that an excessive catalyst is used. It prevents cooling.

The operating cylinder combination pattern shown in FIG. 3 has the minimum required number of patterns that can evenly suspend all the catalysts by the above pattern switching and minimize the number of exhaust systems required. Has been done. That is, in the embodiment according to the present invention, as shown in FIG.
The seventh and seventh cylinders, and the fourth and sixth cylinders are set to the operating cylinder combination pattern so that the cylinders are simultaneously activated and deactivated, respectively. As shown in FIG.
A common exhaust system is provided for each two cylinders to reduce the number of exhaust systems.

Next, the control of the bypass valve 7 during the partial cylinder operation of the embodiment according to the present invention will be described. As described above, it is necessary to increase the intake air amount supplied to the operating cylinders during the partial cylinder operation, but in the embodiment according to the present invention, it is necessary to increase the intake air amount of the entire engine in order to continue supplying the intake air to the idle cylinders. is there. In the embodiment according to the present invention, the opening amount of the throttle valve 6 is changed by increasing the opening amount of the bypass valve 7 in accordance with the decrease in the number of operating cylinders to increase the intake amount supplied through the bypass passage 7. Without increasing the intake amount.

FIG. 5 is a table showing the operation amount of the bypass valve 7 (the number of driving steps of the step motor 71) when switching the number of operating cylinders according to the embodiment of the present invention. In FIG. 5, the horizontal axis represents the number of operating cylinders (FX) before switching the number of operating cylinders, and the vertical axis represents the number of operating cylinders (FY) after switching. For example, if the eight-cylinder operation state (FX = 8) before the switching is changed to the five-cylinder operation state (FY = 5) after the switching, the step motor 71 causes the bypass valve to pass 3 × a steps. 7 is driven in the valve opening direction. Also, for example, before switching 6
If the cylinder operation state (FX = 6) is changed to the 7-cylinder operation state (FY = 7) after the switching, the step motor 71 causes the bypass valve 7 to close in the valve closing direction by 1 × a steps. Driven to. When the number of operating cylinders is the same before and after the switching (FX = FY), the operation amount of the step motor 71 is naturally zero, and the opening degree of the bypass valve 7 is not changed. Here, a is a constant value and is preset according to the type of engine. As can be seen from FIG. 5, the opening degree of the bypass valve 7 is increased by a larger amount as the number of operating cylinders is decreased when the number of operating cylinders is decreased after the switching as compared with the state before the switching, and conversely the number of operating cylinders is changed. If the number of cylinders increases, the larger the number of operating cylinders, the greater the amount of decrease.

Next, the control for changing the number of operating cylinders according to the embodiment of the present invention will be described. If the number of operating cylinders switches during the course of slow acceleration after the vehicle is stopped or decelerated to an extremely low speed, the torque output will change suddenly, giving the driver a great deal of discomfort. . This is because the throttle-torque characteristics after switching change, that is, the torque changes with the same depression amount. For example, if the number of operating cylinders decreases during acceleration after starting, the torque suddenly stops, which is clearly opposite to the driver's desire to accelerate. In this way, the discomfort during starting acceleration is particularly strong and impressive. In the embodiment according to the present invention, in the variable cylinder engine that changes the number of operating cylinders by stopping the fuel injection to some cylinders depending on the engine speed and the load, after decelerating to the vehicle stop state or extremely low speed, When gradual acceleration continues, switching of the number of operating cylinders is prohibited on the way.
Then, when the throttle opening becomes less than a certain throttle opening and the state corresponding to the deceleration request, that is, the acceleration request state is stopped, the prohibition of the switching of the number of operating cylinders is released so that the switching of the number of operating cylinders can be executed. Here, the throttle opening for releasing the prohibition of the switching of the operating cylinder number is a function of the vehicle speed as shown in FIG. 6, and the throttle opening for releasing the prohibition of the switching of the operating cylinder number as the vehicle speed increases. The degree also increases. This is because the running resistance increases as the vehicle speed increases, and the throttle opening required for steady running increases, so that the throttle opening in the decelerated state also increases. The throttle opening for canceling the prohibition of switching the number of operating cylinders as a function of the vehicle speed is R of the ECU 30.
Step 10 of the flowchart of the control operation for switching the number of operating cylinders, which is stored in the OM as a map and will be described later.
It is read and used in 7.

FIG. 7 shows a flowchart of the control operation for switching the number of operating cylinders. First, in step 101, the value of the vehicle speed sensor signal SPD is read, and the process proceeds to step 102, in which the value of the vehicle speed sensor signal SPD is 0.
Determine if it is (zero). Vehicle speed sensor signal SPD = 0,
That is, if the vehicle is in the stopped state, the routine proceeds to step 111, where the switching control prohibition flag XCH for the number of operating cylinders is set (XCH = “1”) and the processing is ended. If the value of the vehicle speed sensor signal SPD is not 0 in step 102, step 1
03, it is determined whether the idle switch XIDL is ON, and if it is ON, the process proceeds to step 104 and ON.
Otherwise, jump to step 105. In step 104, it is judged whether or not the value of the vehicle speed sensor signal SPD is larger than a fixed value a determined in advance by a test, and if it is larger, the routine proceeds to step 105, and if it is smaller, step 111.
Then, the process proceeds to step S3 and sets the switching control prohibition flag XCH for the number of operating cylinders (sets XCH = “1”) and terminates. In step 105, the switching control prohibition flag X for the number of operating cylinders is set.
It is determined whether CH is set (whether XCH = “1”), and if it is set, step 106.
Then, the process proceeds to step 107, the switching control prohibition release throttle opening RTA is calculated based on FIG. 6, and the process proceeds to step 108. In step 105, the switching control prohibition flag XCH for the number of operating cylinders is not set (XC
If H = “0”), jump to step 110. In step 108, it is calculated whether or not the value of the throttle sensor signal TA is smaller than the switching control prohibition release throttle opening RTA. If smaller, the process proceeds to step 109, and if larger, the process ends. At step 109, the switching control prohibition flag XCH for the number of operating cylinders is cleared (XC
(H = “0”) and the process proceeds to step 110. Step 1
At 10, a normal cylinder number switching control routine is executed.

8 to 20 show the details of the cylinder number switching control routine in step 110 in FIG. 7 described above, and FIGS. 8 to 11 show the operating cylinder number switching control of the present invention. In the applied first embodiment, the above-mentioned switching of the combination pattern of the operating cylinders for preventing the excessive cooling of the catalyst is performed every time the number of cylinders changes during the partial cylinder operation. Is. 12 to 15 show the second embodiment to which the operating cylinder number switching control of the present invention is applied, and
The switching of the combination pattern of the operating cylinders for preventing excessive cooling of the catalyst is performed every predetermined time. 16 to 20 show the third embodiment to which the operating cylinder number switching control of the present invention is applied, and
The combination pattern of the operating cylinders is switched to prevent excessive cooling of the catalyst so that the temperature of the catalyst is detected and the temperature of the catalyst does not drop.

First, the first embodiment shown in FIGS. 8 to 11 will be described. In FIG. 8, step 141
Then, it is determined whether or not the current operating condition is the 4-cylinder operation. If it is the 4-cylinder operation, the process proceeds to step 142, and if it is not the 4-cylinder operation, the process jumps to step 151. Step 14
2, the output shaft revolution number NA is read from the automatic transmission output revolution number sensor 32, the engine intake air amount Q is read from the air flow meter 8, and the engine revolution number N is read from the engine revolution sensor (not shown). The intake air amount Q / N is calculated and the routine proceeds to step 143. At step 143, the current engine load status is 4
It is determined whether or not it is within the range where the cylinder operation is performed. If it is within the 4-cylinder operation range, the routine proceeds to step 144. If it is not within the 4-cylinder operation range, the routine proceeds to step 150 (FIG. 9). In step 144, it is determined whether or not the flag F = 1 (whether or not the number of operating cylinders at this routine has changed), and the flag F = 1.
If (the number of operating cylinders has changed in the routine this time), the process proceeds to step 145 to perform the 4-cylinder operation injection pattern switching process, and the process proceeds to step 146 to clear the flag F = 0 and end. If the flag F is not 1 in step 144, the process proceeds to step 147 to continue the injection process of the pattern as it is. It should be noted that the determination as to whether or not the operation range is the 4-cylinder operating range in step 143 is based on the operating range map in FIG.
It is determined using NA and the current number of operating cylinders. The relationship in FIG. 2 is a ROM of the ECU 30 in advance as a three-dimensional map using Q / N, NA, and the current number of operating cylinders.
It is stored in. Hereinafter, in the same manner, 5 shown in FIG.
The control for the cylinder operation, the control for the 6-cylinder operation shown in FIG. 10, and the control for the 7-cylinder operation and the 8-cylinder operation shown in FIG. 11 are performed.

Next, the second embodiment shown in FIGS. 12 to 15 will be described. The features of the second embodiment are as follows.
After the predetermined time has passed, the injection pattern for the same number of operating cylinders is changed so that the catalyst activation capacity is not lost. FIG. 16 shows this predetermined time and is stored in the ROM of the ECU 30 as a map. As shown in FIG. 16, the larger the load, the more air that passes through the catalyst in the idle cylinder and the faster the cooling, and therefore the shorter the pattern switching time, and the larger the rotational speed, the more air that passes through the catalyst per hour. Since the cooling is fast, the pattern switching time is shortened. These map values are experimentally determined so that the activation temperature of the catalyst can be maintained. In FIG. 12, in step 241, it is determined whether or not the current operating condition is the 4-cylinder operation. If it is the 4-cylinder operation, the process proceeds to step 242, and if it is not the 4-cylinder operation, the process jumps to step 251. In step 242, the output shaft speed NA is read from the automatic transmission output speed sensor 32, the engine intake air amount Q is read from the air flow meter 8, and the engine speed N is read from an engine speed sensor (not shown).
The intake air amount Q / N per rotation is calculated and step 24
Go to 3. In step 243, it is determined whether or not the current engine load condition is within the range of four-cylinder operation. If it is within the range of four-cylinder operation, the process proceeds to step 244. ). At step 244, the operation pattern switching time VTIME is read from FIG. 16 and the routine proceeds to step 245. In step 245, the time CTIME after the injection pattern during the current operation measured by the partial cylinder operation continuation counter is compared with the operation pattern switching time VTIME read in step 244, and CT is calculated.
If IME is larger than VTIME, the routine proceeds to step 246, where 4-cylinder operation injection pattern switching processing is performed, and CT
If IME is smaller than VTIME, the process proceeds to step 247 to continue the injection processing of the pattern as it is. In addition,
The determination as to whether or not the operation range is the 4-cylinder operation range in step 243 is made based on the operation range map of FIG. 2 and using the Q / N, NA, and the current number of operating cylinders. Also, the relationship in FIG. 2 is Q
/ N, NA, and a current three-dimensional map using the number of operating cylinders are stored in advance in the ROM of the ECU 30. Hereinafter, similarly, the control for the 5-cylinder operation shown in FIG. 13, the control for the 6-cylinder operation shown in FIG. 14, and the control for the 7-cylinder operation and 8-cylinder operation shown in FIG. 15 are performed.

Next, the third embodiment shown in FIGS. 17 to 20 will be described. The features of the third embodiment are as follows.
When the temperature of the catalyst is lower than a predetermined temperature during the partial cylinder operation, the injection pattern in the same number of operating cylinders is changed so that the activation ability of the catalyst is not lost. As the predetermined temperature T0, a value around 350 degrees at which the activity of the catalyst is not lost is set and stored in the ROM of the ECU 30. In FIG. 17, step 3
In 41, it is determined whether or not the current operating condition is the four-cylinder operation, and if it is the four-cylinder operation, the process proceeds to step 342.
If it is not the four-cylinder operation, the process jumps to step 351. In step 342, the output shaft rotation speed NA is read from the automatic transmission output rotation speed sensor 32, the engine intake air amount Q is read from the air flow meter 8, and the engine rotation speed N is read from an engine rotation speed sensor (not shown). Intake air amount Q / N is calculated and the routine proceeds to step 343. At step 343, the current engine load status is 4
It is determined whether or not it is in the cylinder operation range. If it is in the 4-cylinder operation range, the process proceeds to step 344. If it is not in the 4-cylinder operation range, the process proceeds to step 353 (FIG. 18). At step 344, the catalyst temperature T1 is read and then step 3
Proceed to 45. In step 345, the ROM of the ECU 30
The predetermined temperature T0 stored in the table and the catalyst temperature T1 read in step 344 are compared and calculated. If T0 is larger than T1, the process proceeds to step 346 to perform the 4-cylinder operation injection pattern switching process, and Is smaller than T1, the process proceeds to step 347 to continue the injection processing of the pattern as it is. Similarly, FIG.
The control for the 5-cylinder operation shown in FIG. 8, the control for the 6-cylinder operation shown in FIG. 19, and the control for the 7-cylinder operation and the 8-cylinder operation shown in FIG. 20 are performed.

[0025]

As described above, according to the present invention, in the variable cylinder engine, when the vehicle speed is equal to or lower than the predetermined value, the change of the number of operating cylinders is prohibited until the throttle opening becomes equal to or lower than the predetermined value. As a result, even if the vehicle speed is equal to or lower than the predetermined value, if the throttle opening is equal to or lower than the predetermined value, the number of operating cylinders can be changed and the partial cylinder operation is not restricted more than necessary. Further, the range in which the partial cylinder operation is performed is increased and the fuel efficiency is improved.

[Brief description of drawings]

FIG. 1 is an overall view of an embodiment of a variable cylinder engine to which the present invention is applied. (Common to the first to third embodiments).

FIG. 2 is a diagram showing a relationship between a load state and the number of operating cylinders (common to the first to third embodiments).

FIG. 3 is a diagram illustrating a combination pattern of operating cylinders during partial cylinder operation (common to the first to third embodiments).

FIG. 4 is a diagram showing positions in an ignition sequence of deactivated cylinders during a 5-cylinder operation (common to the first to third embodiments).

FIG. 5 is a diagram showing a drive amount of a step motor when switching the number of operating cylinders (common to the first to third embodiments).

FIG. 6 is a diagram showing a cylinder number control inhibition release throttle opening with respect to a vehicle speed after starting in the control of the number of operating cylinders according to the present invention (common to the first to third embodiments).

FIG. 7 is a flowchart of operating cylinder number control according to the present invention (common to the first to third embodiments).

FIG. 8 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (first embodiment).

FIG. 9 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (first embodiment).

FIG. 10 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (first embodiment).

FIG. 11 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (first embodiment).

FIG. 12 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (second embodiment).

FIG. 13 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (second embodiment).

FIG. 14 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (second embodiment).

FIG. 15 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (second embodiment).

FIG. 16 is a map showing a pattern switching time with respect to engine speed and engine load during partial cylinder operation (second embodiment).

FIG. 17 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (third embodiment).

FIG. 18 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (third embodiment).

FIG. 19 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (third embodiment).

FIG. 20 is a part of a flowchart showing a routine for pattern switching control of operating cylinders (third embodiment).

[Explanation of symbols]

1 ... Engine 3a ... Fuel injection valve 4 ... Intake pipe 5 ... Throttle bypass passage 6 ... Throttle valve 6a ... Throttle opening sensor 7 ... Bypass valve 11, 14 ... Exhaust pipe 12, 13, 15, 18 ... Exhaust pipe 21 ... Three Source catalyst 30 ... ECU 31 ... O ₂ sensor 71 ... Step motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyokazu Umebana 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Toshiaki Asada 1 Toyota Town, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Tokuhiko Nakamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A control device for a variable cylinder engine for an automobile, which controls the number of operating cylinders of an engine according to an engine operating state, wherein a vehicle speed detecting means for detecting a speed of a vehicle and the vehicle speed detecting means detect the speed. The calculation means for comparing the calculated vehicle speed with a preset predetermined value, the throttle opening detection means for detecting the opening of the throttle valve arranged in the engine intake passage, and the throttle opening detection means When the vehicle speed is equal to or lower than a preset predetermined value, the throttle opening is preset. A control device for a variable cylinder engine, characterized in that change of the number of operating cylinders is prohibited until the value becomes equal to or less than a set predetermined value. 2. The variable cylinder engine control device according to claim 1, wherein a predetermined value of the throttle opening for prohibiting a change in the number of operating cylinders is variable according to the vehicle speed.