JP2023070395A - vehicle controller - Google Patents

Abstract

To accurately determine whether cold friction of an engine is increased due to contamination of soot into engine oil.SOLUTION: An electronic control unit 20 calculates an increase amount of a soot concentration of engine oil based on the operation state of an engine 11, and calculates an increase amount of a low-temperature viscosity of the engine oil based on a state quantity indicating a combustion state of an air-fuel mixture and the increase amount of the soot concentration. The electronic control unit 20 determines whether or not cold friction of the engine 11 is increased based on the calculation result of the increase amount of the low-temperature viscosity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle control device that controls a vehicle equipped with an engine.

When engine oil deteriorates due to contamination with soot produced by combustion, the viscosity of the oil increases. As a result, the friction during cold operation of the engine increases, and the startability of the engine may deteriorate. Patent Literature 1 describes determining the presence or absence of deterioration of engine oil in the following manner. First, the amount of soot produced is calculated based on the engine speed and the end timing of fuel injection. An integrated value of the amount of soot generated from the beginning of use of the engine oil is obtained as an index value of the soot concentration in the oil. Then, it is determined whether or not the engine oil has deteriorated based on whether or not the integrated value of the soot generation amount exceeds a certain value.

JP-A-2002-276327

By the way, the properties of the soot produced by the combustion change depending on the combustion conditions of the air-fuel mixture. Depending on the nature of the soot, the increasing tendency of the low-temperature viscosity of the engine oil due to the inclusion of the soot changes. Therefore, it may not be possible to accurately estimate the amount of increase in the low-temperature viscosity of the engine oil just by looking at the soot concentration in the oil.

A vehicle control device for solving the above problems is a device for controlling a vehicle equipped with an engine, and includes an increase calculation process for calculating an increase in the soot concentration of the engine oil based on the operating state of the engine, and a combustion of the air-fuel mixture. Increase amount calculation processing for calculating the amount of increase in viscosity of engine oil at low temperature based on the state quantity indicating the state and the amount of increase in soot concentration, and the state in which the cold friction of the engine has increased based on the calculation result of the increase amount. and a judgment process for judging whether or not there is.

In an engine, the properties of soot generated by combustion of the air-fuel mixture change depending on the combustion state of the air-fuel mixture. The vehicle control device calculates the amount of increase in the low-temperature viscosity of the engine oil based on the amount of increase in the soot concentration of the engine oil and the state quantity indicating the combustion state of the air-fuel mixture. Therefore, the amount of increase in low-temperature viscosity can be calculated in a manner that reflects the difference in the effect of the difference in soot properties on the low-temperature viscosity of engine oil. Then, the vehicle control device determines whether or not the cold friction of the engine is increased based on the calculation result of the amount of increase in the low-temperature viscosity of the engine oil. Therefore, according to the vehicle control device described above, it is possible to accurately determine whether or not the cold friction of the engine is increased due to soot being mixed in the engine oil.

1 is a diagram schematically showing the configuration of an embodiment of a vehicle control device; FIG. 4 is a graph showing the relationship between the soot concentration and low-temperature viscosity of engine oil when the diesel engine is operated under three different engine water temperature and air-fuel ratio conditions. 4 is a flow chart showing a procedure of processing related to determination of increase in cold friction executed by the vehicle control device; 4 is a graph showing the relationship between the viscosity increase rate and the product of the average rotation speed and the average air-fuel ratio in a calculation map used for cold friction increase determination.

An embodiment of the vehicle control device will be described in detail below with reference to FIGS. 1 to 4. FIG.
<Configuration of Vehicle Control Device>
First, referring to FIG. 1, the configuration of the vehicle control device of the present embodiment will be described. The vehicle control device of this embodiment is applied to a vehicle 10 equipped with a diesel engine as the engine 11 serving as a drive source.

As shown in FIG. 1, an engine 11 has a combustion chamber 12 in which an air-fuel mixture is combusted. The engine 11 also includes an intake passage 13 that is an introduction passage for intake air to the combustion chamber 12 and an exhaust passage 14 that is an exhaust passage for exhaust gas from the combustion chamber 12 . The intake passage 13 is provided with an air flow meter 15 for detecting an intake air amount GA and a throttle valve 16 for adjusting the intake air amount GA. A fuel injection valve 17 is installed in the combustion chamber 12 to inject fuel into the intake air introduced into the combustion chamber 12 . The engine 11 also includes a crank angle sensor 19 that detects the rotation angle of a crankshaft 18, which is an output shaft.

An electronic control unit 20 is mounted on the vehicle 10 . The electronic control unit 20 controls equipment mounted on the vehicle 10 including the engine 11 . Detection signals of various sensors for detecting the state of the vehicle 10 are input to the electronic control unit 20 . The sensors whose detection signals are input to the electronic control unit 20 include the airflow meter 15 and the crank angle sensor 19 described above. A signal indicating the state of the ignition switch 21 is also input to the electronic control unit 20 . Then, the electronic control unit 20 executes various controls of the vehicle 10 based on the input detection signal. For example, the electronic control unit 20 controls the operating state of the engine 11 by controlling the opening of the throttle valve 16, the fuel injection amount and timing of the fuel injection valve 17, and the like. The electronic control unit 20 includes a processing device 22 that executes processing for controlling the vehicle 10, and a storage device 23 that stores control programs and data. In this embodiment, such an electronic control unit 20 corresponds to a vehicle control device.

<Increase in low-temperature viscosity of engine oil>
Soot is produced when the air-fuel mixture in the combustion chamber 12 of the engine 11 burns. A part of the soot produced is mixed with the engine oil. As the concentration of soot in the engine oil increases, the low temperature viscosity of the engine oil increases. When the low-temperature viscosity of the engine oil increases, the friction of the engine 11 during cold operation increases. Therefore, when the soot concentration of the engine oil increases, the cold startability of the engine 11 deteriorates and noise and vibration increase during low temperature operation. In the following description, the friction of the engine 11 during cold operation is referred to as "cold friction of the engine 11".

It should be noted that the properties of the soot generated by the combustion of the air-fuel mixture change depending on the combustion state of the air-fuel mixture. The inventors have also confirmed that there is a difference in the increasing tendency of the low-temperature viscosity of the engine oil with respect to the increase in the soot concentration, depending on the properties of the mixed soot.

FIG. 2 shows the relationship between the soot concentration and low-temperature viscosity of the engine oil when the engine 11 is operated under three different engine water temperature and air-fuel ratio conditions. The rate of increase in low temperature viscosity with respect to increase in soot concentration is greater when the engine water temperature is high than when it is low. Also, the ratio of the increase in low-temperature viscosity to the increase in soot concentration is greater when the air-fuel ratio is lean than when the air-fuel ratio is rich. If the air-fuel ratio of the air-fuel mixture is different, the amount of oxygen used for combustion will change, and the combustion state of the air-fuel mixture will change. On the other hand, when the engine water temperature is low, the wall surface temperature of the combustion chamber 12 where the air-fuel mixture is burned also becomes low. When the wall surface temperature of the combustion chamber 12 is low, the amount of fuel adhering to the wall surface of the combustion chamber 12 increases after injection from the fuel injection valve 17, and the combustion state tends to deteriorate. Thus, the engine water temperature and the air-fuel ratio are factors that affect the combustion state of the air-fuel mixture and, in turn, the properties of soot produced by the combustion of the air-fuel mixture.

<Determination of increase in cold friction>
The vehicle control device of the present embodiment determines whether or not the cold friction of the engine 11 is increased due to soot contamination of the engine oil. In the present embodiment, the increase determination is performed in a manner that reflects the difference in the increasing tendency of the low-temperature viscosity of the engine oil due to the properties of the soot as described above.

FIG. 3 shows the processing procedure of the electronic control unit 20 related to the cold friction increase determination. In this embodiment, the electronic control unit 20 starts the series of processes shown in FIG.

When the electronic control unit 20 starts the process of FIG. 3, first, in step S100, the soot concentration increase amount S during trip is acquired. The trip soot concentration increase amount S represents the amount of increase in the soot concentration of the engine oil during the period from the start to the end of the current trip. During operation of the engine 11, the electronic control unit 20 calculates the amount of soot produced by the combustion of the air-fuel mixture based on the operating state of the engine 11 at predetermined calculation intervals. Then, the electronic control unit 20 obtains the soot concentration increase amount S during the trip from a value obtained by integrating the calculated value of the amount of soot generated during the trip. In this embodiment, the process of step S100 corresponds to the increase amount calculation process for calculating the increase amount of the soot concentration of the engine oil.

Subsequently, electronic control unit 20 acquires average engine speed MNE and average air-fuel ratio MABF in step S110. While the engine 11 is running, the electronic control unit 20 calculates the engine speed NE from the detection result of the crank angle sensor 19 . Then, the electronic control unit 20 obtains the average value of the engine speed NE during the period from the start to the end of the trip as the value of the average speed MNE. Further, during operation of the engine 11, the electronic control unit 20 controls the air-fuel mixture burned in the combustion chamber 12 based on the intake air amount GA detected by the air flow meter 15 and the fuel injection amount instructed to the fuel injection valve 17. of the air-fuel ratio ABF. Then, the electronic control unit 20 obtains the average value of the air-fuel ratio ABF during the period from the start to the end of the trip as the average air-fuel ratio MABF.

Subsequently, in step S120, the electronic control unit 20 calculates the viscosity increase rate K from the average engine speed MNE and the average air-fuel ratio MABF. The electronic control unit 20 calculates the viscosity increase rate K using a calculation map MAP pre-stored in the storage device 23 . The viscosity increase rate K represents the ratio of the amount of increase in viscosity at low temperature to the amount of increase in soot concentration of engine oil. The calculation map MAP is configured as a map having as an argument the product of the average engine speed MNE and the average air-fuel ratio MABF (MNE×MABF) and having the viscosity increase rate K as a return value.

FIG. 4 shows the relationship between the product of the average engine speed MNE and the average air-fuel ratio MABF and the viscosity increase rate K in the calculation map MAP. As shown in the figure, the calculation map MAP is set so that the larger the product of the average engine speed MNE and the average air-fuel ratio MABF, the larger the value of the viscosity increase rate K calculated. As the engine speed NE continues to be high, the engine water temperature increases. Therefore, in trips with a large value of the average engine speed MNE, the engine 11 was operated in a state where the engine water temperature was high. Also, in trips with a large average air-fuel ratio MABF, combustion was frequently performed in a lean air-fuel ratio state. Therefore, in a trip where the product of the average engine speed MNE and the average air-fuel ratio MABF is a large value, it is considered that a large amount of soot, which tends to increase the low-temperature viscosity, is mixed in the engine oil. The calculation map MAP is set in a way that reflects these tendencies.

After calculating the viscosity increase rate K in this way, the electronic control unit 20, in step S130 in FIG. Calculate as a value of ΔVS. The amount of increase in viscosity during trip ΔVS represents the amount of increase in viscosity of the engine oil at low temperatures during the period from the start to the end of the current trip. Then, in step S140, the electronic control unit 20 updates the value of the low-temperature viscosity increase amount VS based on the during-trip viscosity increase amount ΔVS. Specifically, in step S140, the electronic control unit 20 updates the value of the low-temperature viscosity increase amount VS so that the sum of the pre-update value plus the trip viscosity increase amount ΔVS becomes the updated value. there is The low-temperature viscosity increase amount VS represents the increase amount of the low-temperature viscosity after the start of use of the engine oil. Incidentally, the value of the low-temperature viscosity increase amount VS is reset to "0" when the engine oil is replaced. In this embodiment, the processing of steps S120 to S140 corresponds to an increase amount calculation process for calculating an increase amount of the low-temperature viscosity of the engine oil based on the state quantity indicating the combustion state of the air-fuel mixture and the increase amount of the soot concentration. are doing.

In the next step S150, the electronic control unit 20 determines whether the vehicle 10 is in a low temperature environment. This determination can be made, for example, based on the measurement results of the outside air temperature and the intake air temperature. In addition, when date information can be acquired, it is possible to determine whether or not the temperature is low by judging from the date whether the temperature is low. Furthermore, if the weather information of the current position of the vehicle 10 can be acquired from the outside, it is possible to determine whether or not the vehicle is in a low temperature environment based on the weather information. If the electronic control unit 20 determines that the environment is not in a low temperature environment (NO), it ends the current process. On the other hand, if the electronic control unit 20 determines that it is in the low temperature environment (YES), the process proceeds to step S160.

When proceeding to step S160, the electronic control unit 20 determines whether or not the low-temperature viscosity increase amount VS exceeds a predetermined determination value. In the present embodiment, it is determined that the cold friction of the engine 11 is increased when the low-temperature viscosity increase amount VS exceeds the determination value. In this embodiment, the process of step S160 corresponds to the determination process of determining whether or not the cold friction of the engine 11 has increased based on the calculation result of the amount of increase in viscosity at low temperature.

When the electronic control unit 20 determines that the cold friction is not in an increased state (S170: NO), the current process ends. On the other hand, when the electronic control unit 20 determines that the cold friction is increased (S170: YES), in step S180, the cold friction increased process is executed. The cold friction increase process is a process for changing the control details of the vehicle 10 in response to an increase in the cold friction of the engine 11 .

<Treatment when cold friction increases>
The cold friction increasing treatment includes, for example, the following treatments. The electronic control unit 20 records the mileage of the vehicle 10 from the start of using the engine oil. Then, the electronic control unit 20 notifies the user of the vehicle 10 that the engine oil needs to be changed when the mileage reaches or exceeds the oil change determination value. When the electronic control unit 20 determines that the cold friction is in an increased state, the electronic control unit 20 sets the oil change determination value to a smaller value than when it is determined that the cold friction is not increased. This is done as a temporary treatment.

Also, in a vehicle equipped with an automatic transmission, the following processing should be included in the cold friction increase processing. An automatic transmission includes a clutch that connects and disconnects power transmission between a transmission input shaft and a transmission output shaft. This clutch is disengaged in the neutral range and engaged in the drive range. When the clutch is engaged when switching from the neutral range to the drive range, the number of rotating elements that rotate together with the transmission input shaft increases. As a result, the drag torque of the torque converter and lockup clutch increases. As the drag torque increases, the rotation load of the engine 11 increases. Therefore, when switching from the neutral range to the drive range, the electronic control unit 20 increases the engine output in order to offset the increase in rotational load due to the increase in drag torque. However, it takes a certain amount of time to increase the engine output. Therefore, the electronic control unit 20 gradually engages the clutch over time. On the other hand, when the cold friction increases, the time required to increase the engine output becomes longer when the engine is cold. Therefore, in a vehicle equipped with an automatic transmission, when the cold friction increases, it is preferable to extend the required time for clutch engagement as the cold friction increasing process.

Furthermore, in a hybrid vehicle including the engine 11 and a generator motor, the following processing should be included in the cold friction increasing processing. In a hybrid vehicle, the engine torque and the power running and regenerative torque of the generator-motor are controlled in order to maintain the charge amount of the battery at a target value. On the other hand, in a hybrid vehicle, the engine 11 is intermittently operated according to the driving condition and the charging condition of the battery. The restart of the engine 11 in the intermittent operation is performed using the power of the generator motor. As the cold friction increases, more electric power is required to restart the engine 11 when cold. Therefore, in such a hybrid vehicle, when the cold friction increases, it is preferable to perform the process of increasing the target value of the battery charge amount more than usual as the cold friction increase process.

<Action and effect of the embodiment>
The action and effect of this embodiment will be described.
The properties of soot generated by combustion of the air-fuel mixture change depending on the combustion state of the air-fuel mixture. Depending on the properties of the soot, the low temperature viscosity of the engine oil may increase significantly even when the soot concentration is low. On the other hand, depending on the properties of the soot, even if the soot concentration of the engine oil is high, the low-temperature viscosity may not increase significantly. Therefore, it may not be possible to appropriately determine whether or not the cold friction of the engine 11 is increased only by the soot concentration of the engine oil.

On the other hand, in the present embodiment, based on the amount of increase in the soot concentration of the engine oil, and the average rotation speed MNE and the average air-fuel ratio MABF, which are state quantities indicating the combustion state of the air-fuel mixture, the low-temperature viscosity of the engine oil A rise amount VS is calculated. Therefore, the low-temperature viscosity increase amount VS can be calculated in a manner that reflects the difference in the influence of the difference in the properties of soot on the low-temperature viscosity of the engine oil. In the present embodiment, it is determined whether or not the cold friction of the engine 11 is increased based on the calculation result of the low-temperature viscosity increase amount VS. Therefore, it can be accurately determined whether or not the cold friction of the engine 11 is increased due to soot contamination of the engine oil.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- As the cold friction increase process, a process different from the above-described process may be performed.

In the above-described embodiment, the amount of increase in soot concentration and the amount of increase in viscosity at low temperature are calculated, and the determination of increase in cold friction is performed for each trip of the vehicle 10 . These calculations and determinations may be performed in different cycles.

In the above-described embodiment, the low-temperature viscosity increase amount VS is calculated using the average engine speed MNE and the average air-fuel ratio MABF as state quantities indicating the combustion state of the air-fuel mixture. A state quantity other than the engine water temperature, which indicates the combustion state of the air-fuel mixture, may be used to calculate the low-temperature viscosity increase amount VS.

The vehicle control device of the above-described embodiment can be applied to an engine other than a diesel engine, such as a gasoline engine, as long as it is an engine in which cold friction increases due to contamination of engine oil with soot.

DESCRIPTION OF SYMBOLS 10... Vehicle 11... Diesel engine 12... Combustion chamber 13... Intake passage 14... Exhaust passage 15... Air flow meter 16... Throttle valve 17... Fuel injection valve 18... Crankshaft 19... Crank angle sensor 20... Electronic control unit 21... Ignition switch 22... Processing device 23... Storage device

Claims (1)

A device for controlling a vehicle equipped with an engine,
an increase calculation process for calculating an increase in the soot concentration of the engine oil based on the operating state of the engine;
an amount-of-increase calculation process for calculating an amount of increase in the low-temperature viscosity of the engine oil based on the state quantity indicating the combustion state of the air-fuel mixture and the amount of increase in the soot concentration;
a determination process for determining whether or not the cold friction of the engine is in an increased state based on the calculated result of the amount of increase;
vehicle control device.

Images