Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can properly adjust cranking torque.SOLUTION: A control device of a hybrid vehicle has an engine, a motor provided on a power transmission passage between the engine and a driving wheel, and a clutch provided at a portion between the engine and the motor on the power transmission passage, and the control device further comprises a first obtaining part that obtains a correlation value intercorrelating with a cumulative operation time of the engine, and a first correcting part that corrects cranking torque so that the cranking torque that is required by the motor in order to crank the engine through the clutch becomes larger as the cumulative operation time shown by the correlation value becomes shorter.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle.

Background Art

[0002] There is known a hybrid vehicle including an engine and a motor as driving power sources, and starting the engine by cranking the engine with the motor (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By reducing the cranking torque within a range that does not affect the starting performance of the engine, it is possible to expand the driving range that can be traveled by the motor and improve fuel efficiency. When cranking the engine, the motor needs to output a cranking torque that can overcome the rotational resistance torque of the engine. However, such rotational resistance torque of the engine is not constant and varies depending on various conditions. Therefore, if the cranking torque is insufficient with respect to the rotational resistance torque, the starting performance of the engine may deteriorate. On the other hand, if the cranking torque is too large with respect to the rotational resistance torque, the driving range that can be traveled by the motor may be reduced.

[0005] Therefore, an object of the present invention is to provide a control device for a hybrid vehicle that can appropriately adjust the cranking torque.

Means for Solving the Problems

[0006] The above object can be achieved by a control device for a hybrid vehicle having an engine, a motor provided on a power transmission path between the engine and drive wheels, and a clutch provided in a portion between the engine and the motor on the power transmission path, the control device including a first acquisition unit that acquires a correlation value correlated with an integrated operation time of the engine, and a first correction unit that greatly corrects a cranking torque required for the motor to crank the engine via the clutch as the integrated operation time indicated by the correlation value is shorter.

[0007] When the integrated operation time indicated by the correlation value is equal to or more than a predetermined value, the first correction unit may set a correction amount of the cranking torque to 0.

[0008] The correlation value may be an integrated travel distance of the hybrid vehicle.

[0009] The control device may further include a second acquisition unit that acquires a temperature of clutch lubricating oil supplied to the clutch, and a second correction unit that corrects the cranking torque lower as the temperature of the clutch lubricating oil is lower.

[0010] The control device may further include a third acquisition unit that acquires atmospheric pressure, and a third correction unit that corrects the cranking torque lower as the atmospheric pressure is lower.

[0011] The control device may further include a fourth acquisition unit that acquires a temperature of cooling water that cools the engine, and a fourth correction unit that corrects the cranking torque higher as the temperature of the cooling water is higher.

[0012] The control device may further include a fifth acquisition unit that acquires a temperature of engine lubricating oil supplied to the engine, and a fifth correction unit that corrects the cranking torque higher as the temperature of the engine lubricating oil is lower.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a control device for a hybrid vehicle that can appropriately adjust the cranking torque.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] [Schematic Configuration of Hybrid Vehicle] FIG. 1 is a schematic configuration diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a K0 clutch 14, a motor 15, a torque converter 18, and a transmission 19 are sequentially provided in the power transmission path from the engine 10 to the drive wheels 13. The engine 10 and the motor 15 are mounted as driving power sources for the hybrid vehicle 1. The engine 10 is, for example, a V-type 6-cylinder gasoline engine, but the number of cylinders is not limited to this, and it may be an in-line gasoline engine or a diesel engine. The K0 clutch 14, the motor 15, the torque converter 18, and the transmission 19 are provided in the transmission unit 11. The transmission unit 11 and the left and right drive wheels 13 are drivingly connected via a differential 12.

[0016] The K0 clutch 14 is provided between the engine 10 and the motor 15 on the same power transmission path. The K0 clutch 14 receives hydraulic pressure supply from the released state and becomes engaged to connect the power transmission between the engine 10 and the motor 15. The K0 clutch 14 becomes released in response to the stop of the hydraulic pressure supply to cut off the power transmission between the engine 10 and the motor 15. The engaged state means that both engaging elements of the K0 clutch 14 are connected and the engine 10 and the motor 15 have the same rotational speed. The released state means that both engaging elements of the K0 clutch 14 are separated.

[0017] The motor 15 is connected to the battery 16 via the inverter 17. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supply from the battery 16, and also functions as a generator that generates electric power for charging the battery 16 in response to power transmission from the engine 10 or the drive wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0018] The inverter 17 is controlled by the ECU 100 described later, converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the motor 15 into a DC voltage. In the case of the power running operation in which the motor 15 outputs torque, the inverter 17 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the motor 15. In the case of the regenerative operation in which the motor 15 generates power, the inverter 17 converts the AC voltage from the motor 15 into a DC voltage and adjusts the power supplied to the battery 16.

[0019] The torque converter 18 is a fluid coupling having a torque amplification function. The transmission 19 is a stepped automatic transmission that switches the gear ratio in multiple steps by switching the gear stage, but is not limited thereto and may be a continuously variable transmission. The transmission 19 is provided between the motor 15 and the drive wheels 13 on the power transmission path. The motor 15 and the transmission 19 are connected via the torque converter 18. The torque converter 18 is provided with a lock-up clutch 20 that receives hydraulic pressure supply and becomes engaged to directly connect the motor 15 and the transmission 19.

[0020] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the transmission 19, and the lock-up clutch 20 via the hydraulic control mechanism 22, respectively. The hydraulic control mechanism 22 is provided with respective hydraulic circuits for the K0 clutch 14, the torque converter 18, the transmission 19, and the lock-up clutch 20, and various hydraulic control valves for controlling their operating hydraulic pressures. Incidentally, a wet clutch may be provided instead of the torque converter 18.

[0021] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as the hybrid vehicle. The ECU 100 is an electronic control unit including an arithmetic processing circuit that performs various arithmetic processes related to the running control of the vehicle, and a memory in which control programs and data are stored. The ECU 100 is an example of a control device for a hybrid vehicle, and specifically, functionally realizes the first to fifth acquisition units and the first to fifth correction units, which will be described in detail later.

[0022] The ECU 100 controls the driving of the engine 10 and the motor 15. Specifically, the ECU 100 controls the torque and rotational speed of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10. The ECU 100 controls the rotational speed and torque of the motor 15 by controlling the inverter 17 to adjust the amount of power transfer between the motor 15 and the battery 16. Further, the ECU 100 performs drive control of the K0 clutch 14, the lock-up clutch 20, and the transmission 19 through the control of the hydraulic control mechanism 22.

[0023] Signals from an ignition switch 71, a crank angle sensor 72, a travel distance sensor 73, an AT oil temperature sensor 74, an atmospheric pressure sensor 75, a water temperature sensor 76, and an engine oil temperature sensor 77 are input to the ECU 100. The crank angle sensor 72 detects the rotational speed of the crankshaft of the engine 10. The travel distance sensor 73 detects the travel distance of the hybrid vehicle 1. The AT oil temperature sensor 74 detects the temperature of the lubricating oil supplied to the K0 clutch 14, the torque converter 18, the transmission 19, and the lock-up clutch 20. The atmospheric pressure sensor 75 detects the atmospheric pressure. The water temperature sensor 76 detects the temperature of the cooling water that cools the engine 10. The engine oil temperature sensor 77 detects the temperature of the lubricating oil that lubricates the drive unit of the engine 10.

[0024] The ECU 100 runs the hybrid vehicle in either a motor mode or a hybrid mode. In the motor mode, the ECU 100 releases the K0 clutch 14 and runs by the power of the motor 15. In the hybrid mode, the ECU 100 switches the K0 clutch 14 to the engaged state and runs by at least the power of the engine 10. Note that the hybrid mode includes a mode of running by only the power of the engine 10 and a mode of running with both the engine 10 and the motor 15 as power sources by powering the motor 15.

[0025] The switching of the running mode is performed based on the required driving force of the vehicle obtained from the vehicle speed and the accelerator opening degree, the state of charge of the battery 16, and the like. For example, when the required driving force is relatively small and the SOC (State Of Charge) indicating the power storage amount of the battery 16 is relatively high, the motor mode in which the engine 10 is stopped is selected to improve fuel efficiency. When the required driving force is relatively large or the SOC of the battery 16 is relatively low, the hybrid mode in which the engine 10 is driven is selected.

[0026] When a predetermined stop condition is satisfied, the ECU 100 executes intermittent operation control to automatically stop the engine 10, and when a predetermined restart condition is satisfied, the ECU 100 restarts the automatically stopped engine 10. For example, when the accelerator opening becomes zero in the hybrid mode, the ECU 100 automatically stops the engine 10 as if the automatic stop condition is satisfied. Further, when the accelerator opening becomes larger than zero, for example, the ECU 100 automatically restarts the engine 10 as if the restart condition is satisfied. At the time of automatic stop, the ECU 100 releases the K0 clutch 14 to stop combustion. At the time of automatic restart, the ECU 100 cranks the engine 10 by the motor 15 via the K0 clutch 14 to start combustion, and then engages the K0 clutch 14.

[0027] Figure 2 is a map showing the relationship between the torque and the rotational speed of the motor 15. The vertical axis represents the torque of the motor 15, and the horizontal axis represents the rotational speed of the motor 15. The solid line in Figure 2 indicates the maximum torque that the motor 15 can output. When the rotational speed of the motor 15 is low, the maximum torque is high, and as the rotational speed of the motor 15 increases, the maximum torque decreases. Here, the motor 15 needs to constantly secure the cranking torque required to crank the above-described engine 10 as surplus torque. For this reason, the driving range that can be traveled in the motor mode is the range obtained by dividing the maximum torque by the cranking torque.

[0028] The wider the driving range in the motor mode, the more the driving frequency of the engine 10 can be suppressed, so the fuel efficiency is improved. For this reason, it is preferable that the cranking torque is as low as possible within a range that does not affect the startability of the engine 10. When cranking the engine 10, the motor 15 needs to output a cranking torque that can overcome the rotational resistance torque that becomes the resistance to the rotation of the engine 10. The rotational resistance torque of the engine 10 is not constant and varies depending on various conditions. In this embodiment, the ECU 100 executes cranking torque correction control so as to cope with such variations in the rotational resistance torque of the engine 10.

[0029] [Cranking Torque Correction Control] FIG. 3 is a flowchart showing an example of cranking torque correction control. This control is repeatedly executed while the ignition is on and the engine 10 is stopped, but is not limited thereto, and may be executed only when there is a start request for the engine 10, for example. First, the ECU 100 acquires the basic cranking torque (step S1). The basic cranking torque is the torque that can appropriately crank the engine 10 obtained by experiments in advance. The basic cranking torque may be a variable value that varies according to the stop position of the engine 10, for example, or may be a predetermined fixed value.

[0030] The ECU 100 acquires the integrated mileage, AT oil temperature, atmospheric pressure, coolant temperature, and engine oil temperature based on the detected values of the mileage sensor 73, AT oil temperature sensor 74, atmospheric pressure sensor 75, coolant temperature sensor 76, and engine oil temperature sensor 77, respectively (step S2). Step S2 is an example of the processing executed by the first to fifth acquisition units.

[0031] The ECU 100 corrects the cranking torque based on the acquired integrated mileage, etc. (step S3). Step S3 is an example of the processing executed by the first to fifth correction units. Specifically, the cranking torque is corrected by adding or subtracting a predetermined correction amount to or from the above-described basic cranking torque. The method for calculating the correction amount will be described below.

[0032] [Method for Calculating Correction Amount] The ECU 100 calculates a plurality of correction amounts with reference to the maps of FIGS. 4A to 6 shown below. FIGS. 4A to 6 are maps for calculating the correction amounts. The maps of FIGS. 4A to 6 are defined based on experimental results and are stored in the memory of the ECU 100.

[0033] FIG. 4A is an example of a map defining the relationship between the integrated travel distance and the correction amount. The vertical axis represents the correction amount [N·m], and the horizontal axis represents the integrated travel distance [km] of the hybrid vehicle 1. In the range where the integrated travel distance is below a predetermined value, the shorter the integrated travel distance, the greater the correction amount increases from 0. The reason for this is as follows. A short integrated travel distance is almost synonymous with a short integrated operation time of the engine 10, and the integrated travel distance is a correlation value that correlates with the integrated operation time of the engine 10. Here, when the engine 10 is new, the mechanical friction torque (hereinafter referred to as the friction torque), which is the rotational resistance torque of the engine 10, is large. As the integrated operation time of the engine 10 increases, the friction torque corresponding to the integrated operation time decreases, and after the so-called running-in operation is completed, the friction torque corresponding to the integrated operation time becomes 0. The motor 15 thus requires a cranking torque sufficient to overcome the friction torque of the engine 10 that varies with the integrated operation time.

[0034] Since the friction torque of the engine 10 varies according to the integrated travel distance in this way, by calculating the correction amount based on the integrated travel distance, the cranking torque can be appropriately adjusted.

[0035] Note that as described above, the integrated travel distance is a correlation value that correlates with the integrated operation time of the engine 10. For example, during traveling in the motor mode, the engine 10 is normally stopped, so the integrated travel distance increases but the integrated operation time of the engine 10 does not increase. Therefore, the longer the integrated travel time in the motor mode, the greater the integrated travel distance, but the integrated operation time of the engine 10 does not increase. However, when the power of the battery 16 is insufficient during traveling in the motor mode, the engine 10 can be driven to switch to traveling in the hybrid mode. Therefore, it is difficult to always travel in the motor mode, and as a result, the integrated travel distance correlates with the integrated operation time of the engine 10.

[0036] Figure 4B is an example of a map defining the relationship between the AT oil temperature and the correction amount. The vertical axis indicates the correction amount [N·m], and the horizontal axis indicates the AT oil temperature [°C]. As the AT oil temperature increases, the correction amount gradually increases from a negative value to a positive value. The reason for this is as follows. The AT oil temperature is the temperature of the lubricating oil supplied to the K0 clutch 14, and the K0 clutch 14 is a wet clutch. Therefore, the lower the AT oil temperature, the higher the viscosity of this lubricating oil, and the greater the torque transmission amount from the motor 15 to the engine 10 via the K0 clutch 14. That is, the lower the AT oil temperature, the greater the torque transmitted from the motor 15 to the engine 10 via the K0 clutch 14.

[0037] Since the AT oil temperature is affected by the outside air temperature, by calculating the correction amount based on the AT oil temperature, the influence of the outside air temperature can be suppressed and the cranking torque can be appropriately adjusted.

[0038] Figure 5A is an example of a map defining the relationship between the atmospheric pressure and the correction amount. The vertical axis indicates the correction amount [N·m], and the horizontal axis indicates the atmospheric pressure [kPa]. When the atmospheric pressure is near the standard atmospheric pressure, the correction amount is 0. When the atmospheric pressure further decreases from a predetermined value lower than the standard atmospheric pressure, the correction amount decreases from 0. Also, when the atmospheric pressure further increases from a predetermined value higher than the standard atmospheric pressure, the correction amount increases from 0. The reason for this is as follows. The higher the atmospheric pressure, the greater the amount of air filled in each cylinder of the engine 10 during cranking, and the lower the atmospheric pressure, the lower the amount of air filled in each cylinder. Here, the compression torque due to the repulsive force that pushes back the piston rising in the compression stroke is the rotational resistance torque of the engine 10, and the magnitude of the compression torque is proportional to the amount of air in the cylinder. During cranking, a cranking torque sufficient to overcome this compression torque is required.

[0039] Since the atmospheric pressure fluctuates due to altitude and weather, by calculating the correction amount based on the atmospheric pressure, the cranking torque can be appropriately adjusted considering such environmental changes.

[0040] FIG. 5B is an example of a map defining the relationship between the cooling water temperature and the correction amount. The vertical axis indicates the correction amount [N·m], and the horizontal axis indicates the cooling water temperature [°C]. As the cooling water temperature becomes higher than a predetermined value, the correction amount increases. This is because when the cooling water temperature becomes high, the sliding parts of the engine 10 expand, and the friction torque of the engine 10 increases. For example, when the engine 10 is restarted shortly after automatic stop, the cooling water temperature is still high. Therefore, by calculating the correction amount based on the cooling water temperature, the cranking torque can be appropriately adjusted.

[0041] FIG. 6 is an example of a map defining the relationship between the engine oil temperature and the correction amount. The vertical axis indicates the correction amount [N·m], and the horizontal axis indicates the engine oil temperature [°C]. As the engine oil temperature decreases below a predetermined value, the correction amount increases from 0. This is because the lower the engine oil temperature, the higher the viscosity, and the friction torque of the engine 10 increases. For example, before the engine 10 has completed warm-up, the engine oil temperature is low. Therefore, by calculating the correction amount based on the engine oil temperature, the cranking torque can be appropriately adjusted even before the engine 10 has completed warm-up.

[0042] By adding all the correction amounts calculated in the above maps to the basic cranking torque as described above, the cranking torque is corrected. In this way, the cranking torque can be adjusted to correspond to the rotational resistance torque of the engine 10 that varies for various reasons.

[0043] In this embodiment, as shown in FIG. 4A, the correction amount is calculated based on the integrated travel distance, but the present invention is not limited thereto. For example, the correction amount may be calculated based on the integrated operation time of the engine 10. Also in this case, similar to the example of FIG. 4A, within the range where the integrated operation time is equal to or less than a predetermined value, the shorter the integrated operation time, the greater the correction amount increases from 0. Generally, in many vehicles, the integrated travel distance is measured by a travel distance sensor, but there are few vehicles provided with a device or the like for measuring the integrated operation time of the engine 10. For this reason, calculating the correction amount based on the integrated travel distance of the vehicle is more versatile than calculating the correction amount based on the integrated operation time of the engine 10.

[0044] In FIGS. 4A to 6, the case where the correction amount changes linearly is illustrated, but the present invention is not limited thereto, and the correction amount may change in a curved shape or in a stepped shape.

[0045] In this embodiment, the case where the cranking torque is corrected by adding the correction amount defined from various viewpoints to the basic cranking torque has been described, but the present invention is not limited thereto. For example, the cranking torque may be corrected by multiplying the basic cranking torque by a correction coefficient defined from various viewpoints.

[0046] In this embodiment, the case where the cranking torque is corrected based on a map has been described, but the present invention is not limited thereto. For example, the cranking torque may be corrected by an arithmetic expression using the basic cranking torque, the integrated travel distance, the AT oil temperature, the atmospheric pressure, the cooling water temperature, and the engine oil temperature as arguments.

[0047] In this embodiment, the case where the cranking torque is corrected based on the integrated travel distance, AT oil temperature, atmospheric pressure, coolant temperature, and engine oil temperature has been described. However, it is not necessarily required to correct the cranking torque based on all of these. For example, depending on the use of the vehicle, it may be limited to use in an environment where the AT oil temperature, atmospheric pressure, coolant temperature, and engine oil temperature do not change significantly. Also, depending on the type of engine, there are some engines with relatively little heat dissipation from the engine and where the coolant temperature and engine oil temperature do not change significantly. In such cases, the cranking torque may be corrected based only on the integrated travel distance.

[0048] In the above embodiment, the case where a hybrid vehicle is controlled by a single ECU100 has been illustrated, but it is not limited thereto. For example, the above-described control may be executed by a plurality of ECUs such as an engine ECU that controls the engine 10, a motor ECU that controls the motor 15, and a clutch ECU that controls the K0 clutch 14.

[0049] As described above in detail with respect to the embodiments of the present invention, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0050] 1 Hybrid vehicle 10 Engine 14 K0 clutch (clutch) 15 Motor 100 ECU (First to Fifth Acquisition Units, First to Fifth Correction Units)

Claims

1. In a control device for a hybrid vehicle having an engine, a motor provided on a power transmission path between the engine and drive wheels, and a clutch provided in a portion between the engine and the motor on the power transmission path, a first acquisition unit that acquires a correlation value correlated with the integrated operation time of the engine; a first correction unit that greatly corrects the cranking torque required by the motor to crank the engine via the clutch as the integrated operation time indicated by the correlation value is shorter. A control device for a hybrid vehicle comprising:

2. The control device for a hybrid vehicle according to claim 1, wherein the first correction unit sets a correction amount of the cranking torque to 0 when the integrated operation time indicated by the correlation value is equal to or greater than a predetermined value.

3. The control device for a hybrid vehicle according to claim 1 or 2, wherein the correlation value is the integrated travel distance of the hybrid vehicle.

4. a second acquisition unit that acquires the temperature of the clutch lubricating oil supplied to the clutch; a second correction unit that corrects the cranking torque lower as the temperature of the clutch lubricating oil is lower. A control device for a hybrid vehicle according to claim 1 or 2, comprising:

5. a third acquisition unit that acquires atmospheric pressure; a third correction unit that corrects the cranking torque lower as the atmospheric pressure is lower. A control device for a hybrid vehicle according to any one of claims 1 to 4, comprising:

6. a fourth acquisition unit that acquires the temperature of cooling water for cooling the engine; a fourth correction unit that corrects the cranking torque greater as the temperature of the cooling water is higher. A control device for a hybrid vehicle according to any one of claims 1 to 5, comprising:

7. a fifth acquisition unit that acquires the temperature of engine lubricating oil supplied to the engine; a fifth correction unit that corrects the cranking torque greater as the temperature of the engine lubricating oil is lower. A control device for a hybrid vehicle according to any one of claims 1 to 6, comprising:

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