JP2021076037A - Internal combustion engine control device - Google Patents

Abstract

To provide an internal combustion engine control device mounted with a variable geometry turbocharger capable of preventing an electric motor from damage due to high temperature.SOLUTION: An internal combustion engine 10 comprises a variable geometry turbocharger 20 having a nozzle vane driven by an electric motor 30. A control device 100 executes: atmospheric temperature calculation processing to calculate an atmospheric temperature of the electric motor 30; current accumulation processing to calculate a cumulative current value, a time integrated value of current flowing through the electric motor 30 while an opening of the nozzle vane is changed; power control processing to reduce power to be supplied to the electric motor 30 when the cumulative current value calculated while the opening of the nozzle vane is changed is equal to or larger than a threshold; and threshold setting processing to lower the threshold to be compared with the cumulative current value with increase in the calculated atmospheric temperature.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for an internal combustion engine including a variable displacement turbocharger.

A variable capacity type turbocharger provided in the intake / exhaust system of an internal combustion engine is known (see Patent Document 1). In such a turbocharger, a plurality of nozzle vanes are provided in a turbine housing in which a turbine wheel is housed. Then, by changing the opening degree of the nozzle vane with an electric motor, the flow velocity of the exhaust gas blown to the turbine wheel is adjusted, thereby adjusting the rotation speed of the turbine wheel of the turbocharger, thereby adjusting the combustion chamber of the internal combustion engine. The boost pressure of the intake air sucked into the turbine is adjusted.

Japanese Unexamined Patent Publication No. 2014-43779

By the way, for example, when changing the opening degree of the nozzle vane in the closing direction, the nozzle vane must be closed while overcoming the flow of the exhaust gas, so that the driving resistance of the nozzle vane increases. Further, when the sliding resistance of the nozzle vane increases due to, for example, the biting of a foreign substance or the adhesion of a deposit, the driving resistance of the nozzle vane increases. When the drive resistance of the nozzle vane increases in this way, the current flowing through the electric motor increases while the opening degree of the nozzle vane is changed, the temperature of the electric motor rises excessively, and the electric motor may be damaged.

The control device for an internal combustion engine that solves the above problems is a control device applied to an internal combustion engine including a variable displacement turbocharger having a nozzle vane driven by an electric motor. This control device includes an atmosphere temperature calculation process for calculating the atmosphere temperature of the electric motor, and a current integration process for calculating an integrated current value which is a time-integrated value of the current flowing through the electric motor while the opening degree of the nozzle vane is changed. When the integrated current value calculated while changing the opening degree of the nozzle vane is equal to or greater than the threshold value, the power limiting process for reducing the power supplied to the electric motor and the higher the ambient temperature, the smaller the threshold value. The threshold setting process for setting the threshold so as to be a value is executed.

The integrated current value, which is the time-integrated value of the current flowing through the electric motor while the opening degree of the nozzle vane is changed, correlates with the calorific value of the electric motor, and the larger the integrated current value, the higher the temperature of the electric motor. Therefore, in the same configuration, when such an integrated current value is equal to or higher than the threshold value while the opening degree of the nozzle vane is changed and there is a concern that the temperature of the electric motor becomes high, a power limiting process for reducing the power supplied to the electric motor is executed. Will be done. Therefore, damage to the electric motor due to high temperature can be suppressed.

Here, as the atmospheric temperature of the electric motor increases, the temperature allowance until the temperature of the electric motor reaches the limit temperature at which the electric motor is damaged decreases. That is, as the atmospheric temperature of the electric motor becomes higher, the temperature of the electric motor reaches the limit temperature even with a smaller amount of heat generation. Therefore, in the same configuration, the threshold value is variably set so that the higher the ambient temperature, the smaller the threshold value. Therefore, even if the ambient temperature is different, the power limiting process is executed before the electric motor reaches the limit temperature, so that the temperature rise of the electric motor can be appropriately suppressed according to the ambient temperature. ..

The schematic diagram which shows the structure of the internal combustion engine with the variable capacity type turbocharger to which this is applied to one Embodiment of a control device. Sectional drawing which shows the structure of the turbine housing of a turbocharger. The schematic which shows the positional relationship between a turbine wheel and each nozzle vane. The flowchart which shows the processing procedure executed by the control apparatus of the same embodiment. The flowchart which shows the processing procedure executed by the control apparatus of the same embodiment. The flowchart which shows the processing procedure executed by the control apparatus of the same embodiment.

Hereinafter, an embodiment in which a control device for an in-vehicle internal combustion engine including a variable displacement turbocharger is embodied will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the compressor housing 21, the intercooler 12, and the intake valve 13 of the turbocharger 20 are attached to the intake passage 11 of the internal combustion engine 10 in this order from the upstream in the intake flow direction. The turbine housing 22 of the turbocharger 20 and the exhaust purification device 15 are attached to the exhaust passage 14 of the internal combustion engine 10 in order from the upstream in the exhaust flow direction.

The turbocharger 20 is an exhaust drive type in which a compressor wheel 21A provided in the compressor housing 21 and a turbine wheel 22A provided in the turbine housing 22 are connected. Further, the turbocharger 20 is configured as a variable capacitance type turbocharger including a variable nozzle mechanism 23 for adjusting the flow velocity of the exhaust gas blown to the turbine wheel 22A.

As shown in FIG. 2, a scroll passage 24 having a spiral shape is provided inside the turbine housing 22. The scroll passage 24 constitutes a part of the exhaust passage 14 of the internal combustion engine 10, and the exhaust gas of the internal combustion engine 10 is sent into the scroll passage 24. Further, inside the turbine housing 22, an annular passage 25 for blowing the exhaust gas sent into the scroll passage 24 toward the turbine wheel 22A is provided along the scroll passage 24. Then, the exhaust gas of the internal combustion engine 10 is blown to the turbine wheel 22A in a state where the flow velocity is increased when passing through the annular passage 25. The annular passage 25 is provided with a plurality of nozzle vanes 26 that open and close in synchronization with each other. The nozzle vane 26 constitutes a part of the variable nozzle mechanism 23.

As shown in FIG. 3, each nozzle vane 26 is arranged around the rotation axis L1 of the turbine wheel 22A at predetermined intervals, and each nozzle vane 26 is synchronously operated by a link mechanism 27 provided in the variable nozzle mechanism 23. The output shaft of the electric motor 30 whose drive current is adjusted by the driver 200 is connected to the variable nozzle mechanism 23. When the link mechanism 27 is operated by the electric motor 30, each nozzle vane 26 is driven to open and close in a synchronized state, and the distance between adjacent nozzle vanes 26 is changed. By adjusting the opening degree of the nozzle vane 26 by the electric motor 30, the flow velocity of the exhaust gas blown from the scroll passage 24 to the turbine wheel 22A is changed, and the rotation speed of the turbine wheel 22A is adjusted to enter the combustion chamber of the internal combustion engine 10. The boost pressure of the inhaled intake air is adjusted.

Various controls of the internal combustion engine 10 are performed by the control device 100. The control device 100 includes a central processing unit (hereinafter referred to as a CPU) 110, a memory 120 in which control programs and data are stored, and the like. Then, the control device 100 executes various control-related processes by executing the program stored in the memory 120 by the CPU 110.

The control device 100 includes a crank angle sensor 41 that detects the crank angle of the crankshaft of the internal combustion engine 10, an air flow meter 42 that detects the intake air amount GA of the internal combustion engine 10, and a cooling water temperature that is the temperature of the cooling water of the internal combustion engine 10. A water temperature sensor 43 that detects THW and an oil temperature sensor 44 that detects oil temperature THO, which is the temperature of the lubricating oil of the internal combustion engine 10, are connected. Further, the control device 100 is connected to an intake air temperature sensor 45 that detects an intake air temperature THA, which is the temperature of the air taken in by the internal combustion engine 10. Further, the control device 100 includes an intake pressure sensor 46 that detects the intake pressure P at a portion downstream of the intake valve 13 in the intake passage 11, and an accelerator position sensor 47 that detects the accelerator operation amount ACCP, which is the operation amount of the accelerator pedal. , A vehicle speed sensor 48 that detects the vehicle speed SP of the vehicle on which the internal combustion engine 10 is mounted is connected. Further, a nozzle opening sensor 49 that detects the nozzle opening VN, which is the nozzle vane 26, is also connected to the control device 100. Then, signals from these various sensors are input to the control device 100. Further, the control device 100 acquires the current Im flowing through the electric motor 30 from the driver 200 that drives the electric motor 30. The control device 100 calculates the engine rotation speed NE based on the output signal of the crank angle sensor 41. Further, the control device 100 calculates the exhaust temperature THEX of the internal combustion engine 10 based on the fuel injection amount Q of the fuel injection valve that supplies fuel to the combustion chamber of the internal combustion engine 10, the engine rotation speed NE, and the like. The exhaust temperature THEX may be actually detected by a sensor or the like.

Then, the control device 100 grasps the engine operating state based on the detection signals of the various sensors, and fuel injection of the fuel injection valve that supplies fuel to the combustion chamber of the internal combustion engine 10 according to the grasped engine operating state. Various engine controls such as adjusting the quantity Q are carried out.

The control device 100 basically feedback-controls the nozzle opening VN of the nozzle vane 26 included in the variable nozzle mechanism 23 as follows. In the present embodiment, the smaller the nozzle opening VN is, the narrower the distance between the adjacent nozzle vanes 26 is, and the nozzle vanes 26 are in the closed side.

The control device 100 calculates the target boost pressure TP based on the engine rotation speed NE and the fuel injection amount Q, and calculates the feedback correction term VNk based on the deviation between the target boost pressure TP and the intake pressure P. .. This feedback correction term VNk is a well-known correction term for PID control, and is a value obtained by adding a proportional term, an integral term, and a differential term calculated separately based on the above deviation.

Further, the control device 100 calculates the basic opening degree VNb of the nozzle vane 26 based on the engine rotation speed NE and the fuel injection amount Q. In the present embodiment, the nozzle opening VN is controlled to be close to full opening in the low supercharging region where the target supercharging pressure TP is low. Further, in the low rotation speed region where the engine rotation speed is low, the nozzle opening VN is controlled to be an opening near fully closed. Further, in the high supercharging region where the target supercharging pressure TP is high, the nozzle opening VN is controlled to be an intermediate opening between the vicinity of the fully open and the vicinity of the fully closed.

Then, the control device 100 sets a value (VNb + VNk) obtained by adding the feedback correction term VNk to the basic opening VNb as the target opening VNt of the nozzle vane 26 so that the nozzle opening VN becomes the target opening VNt. The drive of the electric motor 30 is feedback-controlled via the driver 200.

By the way, when changing the opening degree of the nozzle vane 26 in the closing direction, the nozzle vane 26 must be closed while overcoming the flow of the exhaust gas, so that the driving resistance of the nozzle vane 26 becomes large. Further, when the sliding resistance of the nozzle vane 26 increases due to, for example, the biting of a foreign substance or the adhesion of a deposit, the driving resistance of the nozzle vane 26 increases. When the drive resistance of the nozzle vane 26 increases in this way, the current flowing through the electric motor 30 increases while the opening degree of the nozzle vane 26 is changed, the temperature of the current increases, and the electric motor 30 may be damaged.

Therefore, the control device 100 suppresses damage to the electric motor 30 due to such high temperature by executing the current integration process shown in FIG. 4, the atmosphere temperature calculation process shown in FIG. 5, and the process shown in FIG. There is. Each of these processes is a process realized by the CPU 110 executing the program stored in the memory 120 of the control device 100. Further, in the following, the step number of the procedure shown in each process is expressed by a number with "S" added at the beginning.

The control device 100 repeatedly executes the current integration process shown in FIG. 4 at predetermined execution cycles while the opening degree of the nozzle vane 26 is being changed.
When this current integration process is started, the control device 100 acquires the current Im flowing through the current electric motor 30 (S100). Next, the control device 100 updates the integrated current value ImS, which is the time integrated value of the current Im (S110), and temporarily ends this process. The initial value of this integrated current value ImS is "0". Then, each time the process of S110 is executed, the current ImS acquired in S100 is added to the current integrated current value ImS, so that the value is updated. This integrated current value ImS has a correlation with the calorific value of the electric motor 30, and the larger the integrated current value ImS, the higher the temperature of the electric motor 30. Therefore, in the present embodiment, the integrated current value ImS is calculated as an index value of the calorific value of the electric motor 30. The integrated current value ImS is reset to the initial value when, for example, the opening degree change of the nozzle vane 26 is completed.

The control device 100 repeatedly executes the atmosphere temperature calculation process shown in FIG. 5 at predetermined execution cycles during engine operation.
When this atmospheric temperature calculation process is started, the control device 100 acquires the vehicle speed SP, the accelerator operation amount ACCP, the exhaust temperature THEX, the cooling water temperature THW, the oil temperature THO, and the intake air temperature THA (S200).

Next, the control device 100 calculates the ambient temperature THat, which is the ambient temperature of the electric motor 30, based on each value acquired in S200 (S210). In this S210, the control device 100 has a lower vehicle speed SP, a larger accelerator operating amount ACCP, a higher exhaust temperature THEX, a higher cooling water temperature THW, or a higher oil temperature THO, or sucks. The atmospheric temperature THat is calculated so that the higher the air temperature THA is, the higher the calculated atmospheric temperature THat value is, and this process is temporarily terminated.

The control device 100 repeatedly executes the process shown in FIG. 6 at predetermined execution cycles while the opening degree of the nozzle vane 26 is being changed.
When this process is started, the control device 100 acquires the current values of the integrated current value ImS and the ambient temperature THat (S300).

Next, the control device 100 executes a threshold value setting process for setting the threshold value ImSref based on the acquired atmospheric temperature THat (S310). This threshold value ImSref is the value of the integrated current value ImS when the temperature of the electric motor 30 reaches the limit temperature at which it is damaged by the high temperature. This threshold value ImSref is a value of an integrated current value ImS corresponding to the calorific value of the electric motor 30 required for the current temperature of the electric motor 30 to reach the limit temperature.

Here, as the ambient temperature of the electric motor 30 increases, the temperature allowance until the temperature of the electric motor 30 reaches the limit temperature decreases. That is, as the atmospheric temperature of the electric motor 30 becomes higher, the temperature of the electric motor 30 reaches the limit temperature even with a smaller amount of heat generation. Therefore, in the threshold value setting process of S310, the control device 100 variably sets the threshold value ImSref so that the higher the ambient temperature THat, the smaller the threshold value ImSref.

Next, the control device 100 determines whether or not the integrated current value ImS acquired in S300 is equal to or greater than the threshold value ImSref set in S320 (S320). Then, when the control device 100 determines that the integrated current value ImS is less than the threshold value ImSref (S320: NO), the control device 100 executes a process of increasing the drive current of the electric motor 30 (S330). By increasing the drive current in this way, the drive speed of the nozzle vane 26 becomes faster, so that the opening degree of the nozzle vane 26 is changed faster.

On the other hand, when the control device 100 determines that the integrated current value ImS is equal to or greater than the threshold value ImSref (S320: YES), the control device 100 executes a power limiting process for reducing the power supplied to the electric motor 30 (S340). ). As this power limiting process, the control device 100 executes a process of reducing the drive current of the electric motor 30.

Next, the control device 100 acquires the current nozzle opening degree VN (S350).
Then, the control device 100 determines whether or not the nozzle opening degree VN is the above-mentioned intermediate opening degree (S360). The determination in S360 is performed as follows, for example. That is, for the nozzle opening VN, a value smaller than the fully open opening VNfo on the closing side by a specified value is set as the intermediate opening upper limit value MIDmax. Further, as the nozzle opening degree VN, a value larger than the fully closed opening degree VNfc on the opening side by a specified value is set as the intermediate opening degree lower limit value MIDmin. Then, the control device 100 determines that the nozzle opening VN is an intermediate opening when the acquired nozzle opening VN is an opening between the intermediate opening upper limit value MIDmax and the intermediate opening lower limit value MIDmin. judge.

Then, when the control device 100 determines that the nozzle opening degree VN is not the intermediate opening degree (S360: NO), the control device 100 temporarily ends this process.
On the other hand, when the control device 100 determines that the nozzle opening VN is an intermediate opening (S360: YES), the control device 100 reduces the fuel injection amount Q by a specified amount, more specifically, the process of limiting the fuel injection amount Q. The weight loss correction to be performed is executed (S370), and this process is temporarily terminated.

The power limiting process of S340, the drive current increasing process of S330, and the fuel injection amount Q limiting process of S370 are completed when the opening degree change of the nozzle vane 26 is completed.

The operation and effect of this embodiment will be described.
(1) If the integrated current value ImS is equal to or higher than the threshold value ImSref during the change of the opening degree of the nozzle vane (S320: YES in FIG. 6) and there is a concern that the temperature of the electric motor 30 becomes high, the electric motor 30 is set in S360. A power limiting process is performed to reduce the power supplied to the power supply. Therefore, damage to the electric motor 30 due to high temperature can be suppressed.

Here, as the atmospheric temperature of the electric motor 30 increases, the temperature allowance until the temperature of the electric motor 30 reaches the limit temperature at which the electric motor 30 is damaged decreases. That is, as the atmospheric temperature of the electric motor 30 becomes higher, the temperature of the electric motor 30 reaches the limit temperature even with a smaller amount of heat generation. Therefore, the process of S310 is executed to variably set the threshold value ImSref so that the higher the ambient temperature THat, the smaller the threshold value ImSref. Therefore, even if the atmospheric temperature of the electric motor 30 is different, the power limiting process is executed before the electric motor 30 reaches the limit temperature, so that the temperature rise of the electric motor 30 is appropriately suppressed according to the atmospheric temperature. You will be able to do it.

(2) If the power limiting process described above is executed when the nozzle opening VN is an intermediate opening, the following inconveniences may occur in some cases.
That is, when the nozzle opening VN is an intermediate opening, the boost pressure is high as described above. While changing the opening degree of the nozzle vane 26 in such a high supercharging region, the intake pressure P (actual supercharging pressure) exceeds the target supercharging pressure TP, that is, the supercharging pressure is overshooted. If the pressure rises excessively, inconveniences such as an excessive increase in the engine rotation speed and an excessive increase in the in-cylinder pressure occur. Here, when such an overshoot of the boost pressure occurs, normally, the nozzle opening VN is controlled to the open side in order to converge the intake pressure P (actual boost pressure) to the target boost pressure TP. , The actual boost pressure will decrease.

Here, for example, if the sliding resistance of the nozzle vane 26 increases due to the biting of foreign matter or the adhesion of a deposit, the driving resistance of the nozzle vane 26 increases, so that the electric motor for controlling the nozzle opening VN to the open side The drive current of 30 becomes large. If the above-mentioned power limiting process is executed in such a state, the drive current of the electric motor 30 cannot be increased, so that the drive speed of the nozzle vane 26 may decrease or the nozzle vane 26 may not move in some cases. is there. If the driving speed of the nozzle vane 26 decreases or the nozzle vane 26 becomes immobile, the time required to eliminate the overshoot of the boost pressure becomes longer, or such overshoot is performed while the opening degree of the nozzle vane 26 is being changed. It may be difficult to eliminate the state, and the above-mentioned over-rotation of the internal combustion engine and excessive increase in in-cylinder pressure may continue for a relatively long time.

In this regard, in the present embodiment, when the power limiting process is executed in S340 and the nozzle opening VN is determined to be an intermediate opening (S360: YES), the fuel injection amount Q is in S370. Restriction processing is executed. When such a fuel injection amount Q limiting process is executed, the output torque of the internal combustion engine 10 decreases. Therefore, even if the overshoot state of the boost pressure as described above occurs, the internal combustion engine is over-rotated or excessive. The increase in in-cylinder pressure can be suppressed.

In addition, this embodiment can be implemented by changing as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-In order to calculate the atmospheric temperature THat, the vehicle speed SP, accelerator operation amount ACCP, exhaust temperature THEX, cooling water temperature THW, oil temperature THO, and intake air temperature THA were obtained, but at least one of these values, or at least one of these values, or The atmospheric temperature THat may be calculated based on other values related to the atmospheric temperature of the electric motor 30.

If the process of S330 shown in FIG. 6 is omitted and a negative determination is made in S320, the process shown in FIG. 6 may be temporarily terminated.
-Other processes may be executed as a process for limiting the fuel injection amount Q. For example, the upper limit of the fuel injection amount Q that can suppress the over-rotation of the internal combustion engine and the excessive increase in the in-cylinder pressure as described above is calculated, and the fuel injection amount Q is adjusted so as not to exceed the upper limit value. May be good.

-As the power limiting process, a process of lowering the drive voltage of the electric motor 30 may be executed.
-By omitting each of the above-mentioned processes S350, S360, and S370, the process of limiting the fuel injection amount Q may be omitted. Even in this case, the action and effect described in (1) above can be obtained.

10 ... Internal combustion engine 20 ... Turbocharger 30 ... Electric motor 26 ... Nozzle vane 100 ... Control device

Claims (1)

A control device applied to an internal combustion engine equipped with a variable displacement turbocharger having a nozzle vane driven by an electric motor.
Atmospheric temperature calculation processing for calculating the atmospheric temperature of the electric motor and
The current integration process for calculating the integrated current value, which is the time integrated value of the current flowing through the electric motor while the opening degree of the nozzle vane is being changed, and the current integration process.
When the integrated current value calculated while changing the opening degree of the nozzle vane is equal to or greater than the threshold value, the power limiting process for reducing the power supplied to the electric motor and the power limiting process.
A control device for an internal combustion engine that executes a threshold value setting process for setting the threshold value so that the higher the ambient temperature, the smaller the threshold value.

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