JP2019113046A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine capable of suppressing increase of a bubble fraction in an engine oil.SOLUTION: A control device 10 is applied to an internal combustion engine 80 including an oil pump 83 for force-feeding an engine oil while applying rotation of a crank shaft 81 as a driving source. The control device 10 includes a bubble fraction control portion 11 executing a speed reduction control for reducing an engine speed when an oil pressure of the engine oil is lower than an oil pressure determination value. The bubble fraction control portion 11 determines the oil pressure determination value on the basis of the engine speed and an oil temperature of the engine oil. The bubble fraction control portion 11 stores the oil pressure determination value corresponding to combination of a parameter of the engine speed and a parameter of the oil temperature as a value lower than a representative value of each of measurement values of the oil pressure measured in each of the plurality of internal combustion engines.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device of an internal combustion engine.

  There is known an oil pump whose drive source is the rotation of a crankshaft of an internal combustion engine. As a control device for an internal combustion engine including such an oil pump, Patent Document 1 discloses a control device for increasing the engine rotation speed to increase the oil pressure during a period until the oil pressure of the engine oil reaches a predetermined value after the start of the internal combustion engine. Is disclosed.

JP-A-8-232709

  Air bubbles may be generated in the engine oil which is pressure-fed by the oil pump and circulated in each part of the internal combustion engine. The generation of air bubbles may cause a decrease in the lubricating action of engine oil and the like.

  The air bubble rate, which is the ratio of air bubbles contained in the engine oil, increases as the engine speed increases. This is because air bubbles are generated by the collision of the engine oil stored in the oil pan with the rotating crankshaft.

  Here, for example, in the lash adjuster to which engine oil is supplied, displacement of the plunger moving in the axial direction of the body becomes unstable when air bubbles get caught between the body and the plunger housed inside the body. There is a risk of In addition, when the hydraulic pressure is high, the plunger is kept in a state of protruding from the body, so the influence of air bubbles is small. That is, in the lash adjuster, the higher the hydraulic pressure, the smaller the influence of air bubbles in the engine oil, and the lower the hydraulic pressure, the larger the influence of air bubbles tends to be.

  For this reason, as in Patent Document 1, when the engine rotation speed is increased during a period until the hydraulic pressure reaches a predetermined value, that is, when the hydraulic pressure is low, the bubble rate becomes high in the low hydraulic pressure state, and the influence by the bubbles becomes large. There was a fear.

  A control device of an internal combustion engine for solving the above-mentioned problems is a control device of an internal combustion engine applied to an internal combustion engine including an oil pump that pumps engine oil by using rotation of a crankshaft of the internal combustion engine as a drive source. The air bubble rate control unit executes an engine speed decrease control to reduce the engine speed when the oil pressure of the oil is lower than the oil pressure determination value, and the air bubble rate control unit controls the engine speed and the oil temperature of the engine oil. Setting the hydraulic pressure determination value on the basis of the hydraulic pressure determination value corresponding to the combination of the engine speed parameter and the oil temperature parameter for the plurality of internal combustion engines. It is stored as a value lower than the representative value of each measurement value.

  According to the above configuration, the air bubble rate can be adjusted by controlling the engine speed based on the hydraulic pressure correlated with the allowable value of the air bubble rate in the engine oil. Specifically, when the hydraulic pressure is lower than the hydraulic pressure determination value, the air bubble rate can be reduced by reducing the engine speed. By this, it can suppress that a bubble rate becomes high, so that it exceeds an allowance.

  By the way, when the performances of the plurality of internal combustion engines manufactured based on the same design are compared, the performances of the respective internal combustion engines vary within the range of tolerances of various indexes. In the above configuration, the variation in the performance of the internal combustion engine can be obtained by using the hydraulic pressure determination value set based on the internal combustion engine exhibiting a value lower than the representative value as the value of the hydraulic pressure corresponding to the combination of the engine speed and the oil temperature. Regardless, the bubble rate can be suppressed from exceeding the allowable value.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows one Embodiment of the control apparatus of an internal combustion engine, and the internal combustion engine which is the control object. The figure which shows the relationship between an engine speed and a bubble rate. The flowchart which shows the process of the bubble rate control which the bubble rate control part of the control apparatus performs. Map of hydraulic pressure judgment values used for bubble ratio control. The figure which shows the relationship between engine speed and oil pressure. (A) The figure which shows the relationship between oil pressure and an allowable bubble rate, (b) The figure which shows frequency distribution of a sample internal combustion engine.

Hereinafter, a control device 10 as an embodiment of a control device for an internal combustion engine will be described with reference to FIGS. 1 to 6.
FIG. 1 shows a control device 10 and an internal combustion engine 80 to be controlled.

In the internal combustion engine 80, the crankshaft 81, which is a drive shaft of the internal combustion engine 80, is rotated by the combustion of the mixture of the fuel injected from the fuel injection valve 82 and the intake air.
The internal combustion engine 80 is provided with an oil pump 83 that is driven in conjunction with the rotation of the crankshaft 81. The oil pump 83 discharges the engine oil pumped up from the oil pan and supplies the engine oil to each part of the internal combustion engine 80.

  The internal combustion engine 80 is provided with various sensors for detecting an engine operating state. FIG. 1 shows a crank position sensor 91, an oil pressure sensor 92, and an oil temperature sensor 93 as various sensors.

  Signals from various sensors provided in the internal combustion engine 80 are input to the control device 10. Control device 10 detects engine speed NE based on a detection signal from crank position sensor 91. The control device 10 detects the hydraulic pressure P of the engine oil based on the detection signal from the hydraulic pressure sensor 92. The control device 10 detects the oil temperature T of the engine oil based on the detection signal from the oil temperature sensor 93.

  Control device 10 calculates a target value of the fuel injection amount injected from fuel injection valve 82 based on the operating condition of internal combustion engine 80. More specifically, the control device 10 calculates the basic fuel injection amount based on the engine speed NE and the intake air amount. The control device 10 corrects the basic fuel injection amount to calculate a target fuel injection amount. Further, the control device 10 controls the driving of the fuel injection valve 82 to execute the fuel injection.

  The control device 10 includes an air bubble rate control unit 11 as a functional unit. The air bubble rate control unit 11 executes air bubble rate control for controlling the air bubble rate BF which is a rate of air bubbles contained in the engine oil.

  FIG. 2 shows the relationship between the engine speed NE and the bubble rate BF. As shown in FIG. 2, the higher the engine speed NE, the higher the bubble rate BF, and the lower the engine speed NE, the lower the bubble rate BF. This is because the collision between the engine oil stored in the oil pan and the rotating crankshaft 81 is a generation source of air bubbles, so the higher the engine speed NE, the more easily air bubbles are generated. In the bubble rate control, the bubble rate control unit 11 controls the engine speed NE by correcting the fuel injection amount from the fuel injection valve 82, and controls the bubble rate BF.

With reference to FIG.3 and FIG.4, the processing routine of the bubble ratio control which the bubble ratio control part 11 performs is demonstrated. This processing routine is repeatedly executed at predetermined intervals.
When the execution of this processing routine is started, first, in step S101, the bubble rate control unit 11 determines whether the hydraulic pressure P is lower than the hydraulic pressure determination value Pt. The hydraulic pressure determination value Pt is set by the air bubble rate control unit 11 based on an operation map as shown in FIG. 4. The calculation map is stored in the air bubble rate control unit 11. The air bubble rate control unit 11 reads the value of the hydraulic pressure determination value Pt corresponding to the engine speed NE and the oil temperature T with reference to the calculation map.

  When the hydraulic pressure P is equal to or higher than the hydraulic pressure determination value Pt (S101: NO), this processing routine is temporarily ended. On the other hand, if the hydraulic pressure P is lower than the hydraulic pressure determination value Pt (S101: YES), the process proceeds to step S102.

  In step S102, the air-bubble-rate control unit 11 executes rotational speed reduction control. In the rotational speed reduction control, the target fuel injection amount is calculated by correcting the basic fuel injection amount using the correction value. As the correction value, as a value for decreasing the fuel injection amount injected from the fuel injection valve 82, a value obtained in advance by experiment or the like can be used. Further, the correction value can also be calculated based on the degree of deviation between the hydraulic pressure P and the hydraulic pressure determination value Pt. For example, the correction value may be calculated as a value that decreases the fuel injection amount as the oil pressure P and the oil pressure determination value Pt deviate.

After the rotation speed reduction control is executed in step S102, the processing routine is ended.
The calculation map of the hydraulic pressure determination value Pt will be described with reference to FIG. This operation map has m parameters from NE1 to NEm for the engine speed NE, and n parameters from T1 to Tn for the oil temperature T (m and n are positive integers) . Therefore, in the operation map shown in FIG. 4, a total of (m × n) values are stored as values of the hydraulic pressure determination value Pt corresponding to the combination of the respective parameters. For example, when the value of the engine speed NE is "NE1" and the value of the oil temperature T is "T1", the value of "Pt (NE1, T1)" can be obtained by referring to the calculation map of FIG. Is calculated as the hydraulic pressure determination value Pt.

Next, the values of the hydraulic pressure determination value Pt stored in the operation map of FIG. 4 will be described with reference to FIGS.
FIG. 5 shows the relationship between the engine speed NE and the hydraulic pressure P. The oil temperature T is maintained at a predetermined value. As shown in FIG. 5, the hydraulic pressure P exhibits a higher value as the engine speed NE is higher.

  By the way, when the performance of a plurality of internal combustion engines manufactured based on the same design is investigated, there is a variation in performance among the internal combustion engines. This is because the clearances of the various parts making up the internal combustion engine differ within an acceptable range. Here, an internal combustion engine to be investigated is a "sample internal combustion engine". Each sample internal combustion engine is an internal combustion engine manufactured based on the same design. FIG. 5 shows the relationship between the engine speed NE and the hydraulic pressure P for four sample internal combustion engines A, B, C, D as an example. As shown in FIG. 5, even if the value of the engine speed NE is the same, the hydraulic pressure P detected in the order of the sample internal combustion engines A to D shows a high value.

  FIG. 6A shows the relationship between the hydraulic pressure P and the allowable bubble ratio BFA, which is the allowable value of the bubble ratio BF. Here, the allowable bubble rate BFA is set as a value that can ensure the operation of the lash adjuster provided in the internal combustion engine 80. In the lash adjuster to which engine oil is supplied, when air bubbles get caught between the body and the plunger housed inside the body, the displacement of the plunger moving in the axial direction of the body may become unstable. In addition, when the hydraulic pressure is high, the plunger is kept in a state of protruding from the body, so the influence of air bubbles is small. That is, in the lash adjuster, the higher the hydraulic pressure, the smaller the influence of air bubbles in the engine oil, and the lower the hydraulic pressure, the larger the influence of air bubbles tends to be. The allowable bubble ratio BFA set based on such a tendency is correlated with the hydraulic pressure P as shown in FIG. 6A, and the higher the hydraulic pressure P, the higher the value.

  As described with reference to FIG. 5, the performance among the internal combustion engines varies, and the hydraulic pressure P detected by the hydraulic pressure sensor 92 is different for each internal combustion engine even if the engine speed NE is the same value. . In FIG. 6B, when the sample internal combustion engine is being operated at a predetermined engine speed NE and a predetermined oil temperature T with the oil pressure P and a plurality of sample internal combustion engines as a population, the oil pressure P is the oil pressure sensor 92. The frequency distribution based on the frequency of the sample internal combustion engine detected by

  In this frequency distribution, the arithmetic mean of the hydraulic pressure P is “μ” and the standard deviation is “σ”. In the present embodiment, with regard to the hydraulic pressure P measured when each sample internal combustion engine is operated at the engine speed NEx (x: 1 to m) and the oil temperature Ty (y: 1 to n) The hydraulic pressure determination value Pt corresponding to the combination of the engine speed NEx and the oil temperature Ty is set as the value of “. Then, the operation map shown in FIG. 4 is created based on the total (m × n) hydraulic pressure determination values Pt. Therefore, in the operation map shown in FIG. 4, “μ−2σ” which is a value lower than the average value “μ” is stored as the hydraulic pressure determination value Pt.

  That is, in the control device 10, the hydraulic pressure determination value Pt stored as a value lower than the average value “μ”, which is a representative value of the hydraulic pressure P, in the process of step S101 in the bubble ratio control described with reference to FIG. It is determined whether or not the rotation speed reduction control to be executed in step S102 is executable, with Therefore, when the hydraulic pressure P is lower than the hydraulic pressure determination value Pt, the engine speed reduction control is performed to reduce the engine speed NE.

The operation and effects of the present embodiment will be described.
According to the control device 10, the bubble rate BF can be adjusted by controlling the engine speed NE based on the hydraulic pressure P correlated with the allowable bubble rate BFA. Specifically, the bubble rate BF can be reduced by decreasing the engine speed NE when the hydraulic pressure P is lower than the hydraulic pressure determination value Pt. By this, it can suppress that the bubble rate BF becomes high.

  Further, as shown in FIG. 6 (b), when the engine rotational speed NE and the hydraulic pressure P are operated under the same condition, the internal combustion engine having a half or more of the sample internal combustion engines is higher than "μ-2σ" The hydraulic pressure P is detected. Therefore, when the internal combustion engine is operated under the same conditions, the allowable bubble ratio BFA corresponding to the hydraulic pressure P is a value equal to or more than "BFAL" shown in FIG. Therefore, assuming that the hydraulic pressure determination value Pt is “μ−2σ” which is a value lower than the average value “μ”, the actual allowable bubble rate BFA corresponding to the hydraulic pressure P is the hydraulic pressure determination value Pt It will be a higher value. By controlling the bubbling rate BF using the hydraulic pressure determination value Pt, in which a value lower than the average value, which is a representative value, as described above is stored as a threshold, bubbles are generated regardless of variations in performance of the internal combustion engine. It is possible to suppress that the rate BF exceeds the allowable bubble rate BFA.

  An antifoaming agent may be added to the engine oil to lower the bubble rate BF in the engine oil. According to the control device 10, when the bubble rate BF may exceed the allowable bubble rate BFA, the bubble rate BF can be decreased by the reduction of the engine speed NE, so the amount of the antifoamer added is reduced. be able to.

The present embodiment can be modified as follows. The present embodiment and the following modifications can be implemented in combination with one another as long as there is no technical contradiction.
In the embodiment described above, the engine speed reduction control executed by the air bubble rate control unit 11 is configured to reduce the engine speed NE by reducing the fuel injection amount. The configuration for reducing the engine rotational speed NE in the rotational speed reduction control is not limited to reducing the fuel injection amount. For example, in the rotational speed reduction control, the throttle valve may be controlled to the closing side so as to reduce the intake air amount. As the amount of intake air decreases, the engine speed NE can be reduced.

  In the above embodiment, in the frequency distribution described with reference to FIG. 6B, the operation map illustrated in FIG. 4 is created with the value of “μ−2σ” as the hydraulic pressure determination value Pt. The value that can be adopted as the hydraulic pressure determination value Pt is not limited to this. If a value lower than the average value is stored as the hydraulic pressure determination value Pt in the operation map, the actual allowable bubble ratio BFA corresponding to the hydraulic pressure P often becomes higher than the hydraulic pressure determination value Pt. The difference between the actual allowable bubble ratio BFA corresponding to the hydraulic pressure P and the hydraulic pressure determination value Pt can be increased as the value stored as the hydraulic pressure determination value Pt is set to a value lower than the average value.

  In the above embodiment, in the frequency distribution described with reference to FIG. 6B, the average value of the hydraulic pressure P is treated as a representative value, but the median may also be treated as a representative value. Also, the mode value can be treated as a representative value.

  DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 11 ... Air bubble rate control part, 80 ... Internal combustion engine, 81 ... Crankshaft, 82 ... Fuel injection valve, 83 ... Oil pump, 91 ... Crank position sensor, 92 ... Oil pressure sensor, 93 ... Oil temperature sensor.

Claims (1)

A control device for an internal combustion engine applied to an internal combustion engine provided with an oil pump that pumps engine oil by using rotation of a crankshaft of the internal combustion engine as a drive source,
The air bubble rate control unit executes an engine speed reduction control that reduces the engine speed when the oil pressure of the engine oil is lower than the oil pressure determination value.
The bubble rate control unit sets the hydraulic pressure determination value based on the engine speed and the oil temperature of the engine oil, and the hydraulic pressure corresponds to a combination of the engine speed parameter and the oil temperature parameter. A control device for an internal combustion engine, which stores a determination value as a value lower than a representative value of measured values of the hydraulic pressure measured for a plurality of internal combustion engines.