Control device for a hybrid vehicle

Abstract

To provide a controller of a hybrid vehicle which suppresses a feeling of slowness when starting a vehicle.SOLUTION: A controller of the invention is applied to a hybrid vehicle which includes an engine, a motor arranged on a power transmission path between the engine and drive wheels, and a battery supplying the motor with power, and which can be shifted from an EV mode into an HV mode. The controller of the hybrid vehicle comprises: a first acquisition part which acquires a first gradient value of a road surface where the hybrid vehicle is positioned in the EV mode, a first residual quantity of the battery, and a first temperature thereof; a first calculation part which calculates based on the gradient value acquired by the first acquisition part, a first threshold value that is a lower limit value of gradient where output power of the battery is insufficient for starting the hybrid vehicle by use of the motor and simultaneously activating the engine; a first determination part which determines whether or not the first gradient value is the first threshold value or more; and an engine control part which starts, in the case that the first gradient value is the first threshold or more, the engine and shifts into the HV mode before starting the hybrid vehicle when the hybrid vehicle is stationary.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] In a hybrid vehicle, when shifting from an EV mode using a motor as a driving power source to an HV mode using at least an engine as a driving power source, the engine is started by the motor. Such a shift from the EV mode to the HV mode may be performed at the time of starting the vehicle. In this case, since the motor needs to start the engine while starting the vehicle, there is a risk that the torque of the motor is insufficient. In particular, when the remaining amount of the battery is insufficient or when driving on an uphill road, there is a risk of jerking at the time of starting. For example, Patent Document 1 describes a technique for determining whether or not to shift from the EV mode to the HV mode in consideration of the remaining amount of the battery and the gradient of the uphill road.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power value that can be output by the battery varies not only depending on the remaining amount of the battery but also depending on the temperature of the battery. For this reason, for example, even when the remaining amount of the battery is sufficient and the gradient of the uphill road is small, depending on the temperature of the battery, sufficient power cannot be output to the motor, and there is a risk that jerking occurs due to insufficient torque of the motor when shifting from the EV mode to the HV mode at the time of starting.

[0005] Therefore, an object of the present invention is to provide a control device for a hybrid vehicle that suppresses jerking at the time of starting.

Means for Solving the Problem

[0006] The above object is applied to a hybrid vehicle having an engine, a motor provided in a power transmission path between the engine and drive wheels, and a battery that outputs power to the motor. The control device of the hybrid vehicle is capable of shifting from an EV mode that uses the motor as a driving power source without using the engine to an HV mode that uses at least the engine as a driving power source by starting the engine with the motor. The control device includes: a first acquisition unit that acquires a first gradient of a road surface on which the hybrid vehicle is located, a first remaining amount, and a first temperature of the battery in the EV mode; a first calculation unit that calculates a first threshold value, which is a lower limit value of a gradient at which the output power of the battery is insufficient to start the engine while starting the hybrid vehicle with the motor based on the first remaining amount and the first temperature; a first determination unit that determines whether the first gradient is greater than or equal to the first threshold value; and an engine control unit that starts the engine before starting when the hybrid vehicle is stopped and shifts from the EV mode to the HV mode when the first gradient is greater than or equal to the first threshold value. 0. The first calculation unit calculates the first threshold value to be smaller as the first temperature is lower, and the first calculation unit calculates the first threshold value to be smaller as the first remaining amount is less. A second acquisition unit that acquires a second gradient of a road surface on which the hybrid vehicle is located in the HV mode, a second remaining amount, and a second temperature of the battery; a second calculation unit that calculates a second threshold value, which is an upper limit value of a gradient on which the vehicle can travel in the EV mode, based on the second remaining amount and the second temperature; and a second determination unit that determines whether the second gradient is less than or equal to the second threshold value. The engine control unit stops the engine from the HV mode and shifts to the EV mode when the second gradient is less than or equal to the second threshold value. The second calculation unit calculates the second threshold value to be smaller as the second temperature is lower, and the second calculation unit calculates the second threshold value to be smaller as the second remaining amount is less. The first calculation unit calculates a first power value that can be output by the battery so as to increase as the first remaining amount is larger, calculates a first temperature correction coefficient that decreases from 1 as the first temperature is lower and decreases as the first remaining amount is less, and calculates the first threshold value to be smaller as the value obtained by multiplying the first temperature correction coefficient by the first power value is smaller. The second calculation unit calculates a second power value that can be output by the battery so as to increase as the second remaining amount is larger, calculates a second temperature correction coefficient that decreases from 1 as the second temperature is lower and decreases as the second remaining amount is less, and calculates the second threshold value to be smaller as the value obtained by multiplying the second temperature correction coefficient by the second power value is smaller. When the value obtained by multiplying the first temperature correction coefficient by the first power value is the same as the value obtained by multiplying the second temperature correction coefficient by the second power value, the second threshold value is smaller than the first threshold value. It can be achieved by a control device for a hybrid vehicle.

[0009] The first acquisition unit acquires a shift position, and the engine control unit may start the engine before starting when the hybrid vehicle is stopped and shift to the HV mode when the first gradient is greater than or equal to the first threshold value and the shift position is in any of the drive range, brake range, and reverse range.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a control device for a hybrid vehicle that suppresses jerk during starting.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0016] [Schematic Configuration of Hybrid Vehicle] FIG. 1 is a schematic configuration diagram of a hybrid vehicle 10. The hybrid vehicle 10 includes an engine 200 and a motor 220 as driving power sources for traveling. The engine 200 is a gasoline engine or a diesel engine. The motor 220 receives power from a battery 310 described later via a power conversion device 300 and rotates for driving. Further, the motor 220 also operates as a generator that generates power by rotating. In addition, the motor 220 can also generate power for starting the engine 200.

[0017] A first clutch 210 is provided between the engine 200 and the motor 220. The first clutch 210 engages, slips, and disengages the engine 200 and the motor 220. A second clutch 230 is provided between the motor 220 and the transmission 240. The second clutch 230 engages, slips, and disengages the motor 220 and the transmission 240. The first clutch 210 and the second clutch 230 are switched between engagement, slip, and disengagement according to the hydraulic pressure supplied from a hydraulic control device (not shown).

[0018] The transmission 240 is a transmission that switches a stepped gear ratio such as five forward speeds and one reverse speed, for example. The gear ratio is switched according to, for example, the vehicle speed, the accelerator opening degree, and the like. Although the second clutch 230 is provided separately from the transmission 240, some of the plurality of friction engagement elements engaged in each gear stage of the transmission 240 may be diverted. The output shaft of the transmission 240 is connected to drive wheels 251 and 252, which are rear wheels, via a propeller shaft PS as a vehicle drive shaft, a differential 250, a left drive shaft DSL, and a right drive shaft DSR. Incidentally, the hybrid vehicle 10 also includes wheels 253 and 254, which are front wheels.

[0019] The power conversion device 300 includes an inverter and a converter, and can drive the motor 220 by converting the DC power from the battery 310 into an AC current and outputting it to the motor 220. Further, the power conversion device 300 can charge the battery 310 by converting the AC power generated by the motor 220 into a DC current and outputting it to the battery 310. The battery 310 is a rechargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery.

[0020] The ECU (Electronic Control Unit) 100 is an electronic control unit including an arithmetic processing circuit that performs various arithmetic processes related to the driving control of the hybrid vehicle 10, 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 implements a first and a second acquisition unit, a first and a second calculation unit, a first and a second determination unit, and an engine control unit, which will be described later in detail. The SOC sensor 510, the temperature sensor 520, the gradient sensor 530, the vehicle speed sensor 540, and the shift position sensor 550 are electrically connected to the ECU 100.

[0021] The SOC sensor 510 detects the remaining amount (SOC: State Of Charge) of the battery 310. The temperature sensor 520 detects the temperature of the battery 310. The temperature sensor 520 is installed around (inside or on the surface of) the battery 310. The temperature sensor 520 is, for example, a thermistor, a thermocouple, a varistor, etc., but is not limited thereto, and all elements that can convert temperature into electrical resistance can be used. Incidentally, the ECU 100 may obtain the remaining amount of the battery 310 by estimating it by a known method without using the SOC sensor.

[0022] The gradient sensor 530 detects the gradient of the road surface on which the hybrid vehicle 10 is located. The gradient sensor 530 detects the uphill side as a positive value. Incidentally, the ECU 100 may obtain the gradient of the road surface on which the hybrid vehicle 10 is located by using a navigation system. The vehicle speed sensor 540 detects the vehicle speed of the hybrid vehicle 10.

[0023] The shift position sensor 550 detects the shift position of the shift lever. For example, the shift position sensor 550 detects whether it is in the parking range (P range) used when parking, the reverse range (R range) for reverse driving, the neutral range (N range), the normal drive range (D range) for forward driving, or the brake range (B range) where the braking force applied to the vehicle when the accelerator is off during driving is set larger than that in the D range but the driving force setting when the accelerator is on is the same as that in the D range.

[0024] The ECU 100 can control the driving mode of the hybrid vehicle 10 to either an EV mode in which the motor 220 is used without using the engine 200 as a driving power source or an HV mode in which at least the engine 200 is used as a driving power source. In the EV mode, the first clutch 210 is disengaged to disconnect the engine 200 from the drive train, and the second clutch 230 is engaged to drive using only the power of the motor 220. In the HV mode, the first clutch 210 is engaged to connect the engine 200 to the drive train, and the second clutch 230 is engaged to drive using at least the power of the engine 200. Note that in the HV mode, in addition to the engine 200, the motor 220 can also be used as a driving power source, and the motor 220 can also be used as a generator.

[0025] [Shift from EV Mode to HV Mode] When, for example, the ECU 100 aims to improve fuel efficiency by stopping the engine 200, it controls the driving mode to the EV mode, and when the required torque is high or the remaining amount of the battery 310 is low, it controls the driving mode to the HV mode.

[0026] Here, when shifting from the EV mode to the HV mode, the first clutch 210 is slipped and the engine 200 is cranked by the motor 220 to start the engine 200, and then the first clutch 210 is engaged. This shift may be performed when the vehicle starts. This is because the required torque increases when the vehicle starts. Therefore, at the start, the motor 220 needs to drive both the drive wheels 251 and 252 for starting while starting the engine 200. For example, when driving uphill, the torque required for starting increases. Also, when the remaining amount of the battery 310 is low, there is a possibility that the torque of the motor 220 cannot be ensured. Furthermore, when the battery 310 is at a low temperature, even if the remaining amount of the battery 310 is sufficient, the actual available power value may be low. Thus, when the remaining amount of the battery 310 is low or the battery 310 is at a low temperature during uphill driving, if shifting from the EV mode to the HV mode at the start, it may not be possible to sufficiently ensure both the torque for starting the engine 200 and the torque for starting, which may give the driver a jerky feeling.

[0027] Therefore, in this embodiment, the ECU 100 starts the engine 200 in advance while the vehicle is stopped in the EV mode under predetermined conditions and shifts to the HV mode. FIG. 2 is a timing chart showing an example of the transition from the EV mode to the HV mode. FIG. 2 shows the depression amounts of the accelerator pedal and the brake pedal, the shift position, the vehicle speed, the slope gradient, the output power of the battery 310, the rotational speeds of the engine 200 and the motor 220, the input rotational speed to the transmission 240, and the transitions of the torques of the engine 200 and the motor 220. The depression amount of the accelerator pedal, the vehicle speed, the rotational speed and torque of the engine 200 are indicated by solid lines. The depression amount of the brake pedal, the rotational speed and torque of the motor 220 are indicated by dotted lines. The input rotational speed to the transmission 240 is indicated by a dashed-dotted line. Also, the output power of the battery 310 is indicated by a dotted line at normal temperature and by a solid line at low temperature. FIG. 2 shows a case where the driving mode is the EV mode, the shift position is in the drive range, the vehicle is traveling on an uphill slope with a gradient equal to or greater than a threshold value A described later, and the battery 310 is at a low temperature. The EV mode is a state in which the first clutch 210 is released, the engine 200 is stopped, and the second clutch 230 is engaged and the vehicle is traveling by the power of the motor 220.

[0028] During driving in the EV mode where the rotational speed of the motor 220 matches the input rotational speed to the transmission 240, when the depression amount of the accelerator pedal decreases and the depression amount of the brake pedal increases, the vehicle speed becomes zero at time t1 and the vehicle stops. After a predetermined time has elapsed in this state at time t2, the start control of the engine 200 is started. Specifically, in the stopped state, the second clutch 230 is disengaged and the rotational speed of the motor 220 increases. At time t3, the first clutch 210 is controlled from disengagement to slip, and the engine 200 is cranked by the motor 220 and the rotational speed of the engine 200 increases. Thereafter, when the rotational speed of the engine 200 rises to the rotational speed of the second clutch 230 at time t4, the first clutch 210 is engaged, fuel injection and fuel ignition are started in the engine 200, the torque of the engine 200 starts to increase, and the torque of the motor 220 is controlled to decrease. At time t5, the torque of the motor 220 decreases to zero, and the torque of the engine 200 rises to the torque during idling operation. At time t6, the depression amount of the brake pedal becomes zero and the depression amount of the accelerator pedal gradually increases. At time t7, the second clutch 230 is engaged, and the torque of the engine 200 further increases according to the depression amount of the accelerator pedal, the rotational speed of the engine 200 and the input rotational speed to the transmission 240 increase, and the hybrid vehicle 10 starts moving forward.

[0029] In this way, since the engine 200 is started by the motor 220 during a stop, it is possible to prevent the torque of the motor 220 from being simultaneously taken away for starting the engine 200 and driving the drive wheels 251 and 252 at the time of starting. Therefore, the jerk at the time of starting can be suppressed. Also, as will be described in detail below, since the possibility of shifting to the HV mode during a stop is determined in consideration of the temperature of the battery 310, it is possible to avoid the occurrence of a jerk even when the power value that can be output from the battery 310 decreases.

[0030] Figure 3 is a flowchart showing an example of the shift control from the EV mode to the HV mode executed by the ECU 100. The control in Figure 3 is repeatedly executed. The ECU 100 determines whether the driving mode is the EV mode (step S1). If the answer in step S1 is No, this control ends. If the answer in step S1 is Yes, the ECU 100 acquires the remaining amount and temperature of the battery 310, the gradient of the driving road surface, the vehicle speed, and the shift position based on the detection values of the SOC sensor 510, the temperature sensor 520, the gradient sensor 530, the vehicle speed sensor 540, and the shift position sensor 550 (step S2). Step S2 is an example of the process executed by the first acquisition unit. Also, the remaining amount, temperature, and gradient of the battery 310 acquired by the ECU 100 in step S2 correspond to the first remaining amount, the first temperature, and the first gradient, respectively.

[0031] Next, the ECU 100 calculates the power value that can be output by the battery 310 based on the remaining amount and temperature of the battery 310 acquired in step S2 (step S3). Specifically, first, the power value that can be output by the battery 310 is calculated based on the remaining amount of the battery 310, and then the calculated power value that can be output is corrected based on the temperature of the battery 310, and the final power value that can be output is calculated.

[0032] First, the ECU 100 calculates the power value that can be output by the battery 310 with reference to the following map. Figure 4A is a map defining the relationship between the remaining amount of the battery 310 and the power value that can be output by the battery 310. The horizontal axis shows the remaining amount of the battery 310 [%], and the vertical axis shows the power value that can be output by the battery 310 [kW]. As shown in Figure 4A, the greater the remaining amount of the battery 310, the greater the power value that can be output by the battery 310. After calculating the power value that can be output by the battery 310 with reference to the map in Figure 4A, the ECU 100 corrects the power value that can be output with the following map.

[0033] FIG. 4B is a map showing the relationship between the temperature [°C] of the battery 310 and the temperature correction coefficient K. The horizontal axis indicates the temperature of the battery 310, and the vertical axis indicates the temperature correction coefficient K. The temperature correction coefficient K has a maximum value of 1 and gradually decreases as the temperature of the battery 310 decreases. This is because the resistance of the battery 310 increases as the temperature of the battery 310 decreases. Also, the temperature correction coefficient K takes different values according to the remaining amount of the battery 310, and the lower the remaining amount of the battery 310, the greater the decrease in the temperature correction coefficient K with respect to the temperature decrease. FIG. 4B illustrates the cases where the remaining amounts of the battery 310 are 100%, 60%, and 30%, respectively. The ECU 100 multiplies the power value that can be output calculated with reference to the map of FIG. 4A by the temperature correction coefficient K calculated with reference to the map of FIG. 4B to calculate the final power value that the battery 310 can output.

[0034] Note that the map of FIG. 4B shows only three remaining amounts of the battery 310, which are 100%, 60%, and 30%. In reality, the remaining amount is more than the amount that allows the vehicle to run in the EV mode, and the temperature correction coefficient K is defined for each remaining amount. Also, the maps of FIGS. 4A and 4B are obtained in advance through experiments and stored in the memory of the ECU 100. The method for calculating the power value that the battery 310 can output is not limited to referring to the maps as described above, and may be calculated by, for example, an arithmetic expression.

[0035] Next, the ECU 100 calculates a threshold value A based on the power value that the battery 310 can output (step S4). Specifically, the ECU 100 calculates the threshold value A by referring to the following map. FIG. 5 is a map that defines the relationship between the power value [kW] that the battery 310 can output and the gradient [%]. The horizontal axis indicates the power value that the battery 310 can output, and the vertical axis indicates the gradient. The threshold value A increases as the power value that can be output increases. The threshold value A is the lower limit value of the gradient at which the output power of the battery 310 is insufficient to start the engine 200 while starting the hybrid vehicle 10 by the motor 220 based on the remaining amount and temperature of the battery 310 obtained in step S2. Note that the map in FIG. 5 is obtained in advance by experiments and stored in the memory of the ECU 100. The method for calculating the threshold value A is not limited to referring to the map as described above, and may be calculated by an arithmetic expression, for example. The threshold value A is an example of a first threshold value. Steps S3 and S4 are examples of processes executed by the first calculation unit. Note that the threshold value a shown in FIG. 5 will be described later.

[0036] Next, the ECU 100 determines whether the vehicle speed obtained in step S2 is less than the speed α and whether the gradient obtained in step S2 is greater than or equal to the threshold value A (step S5). The speed α is a value close to zero at which the hybrid vehicle 10 can be regarded as being in a stopped state. Step S5 is an example of a process executed by the first determination unit.

[0037] If the result in step S5 is Yes, the ECU 100 increments the counter B (step S6). If the result in step S5 is No, the ECU 100 resets the counter B (step S7). The counter B is a counter for determining whether the state determined to be Yes in step S5 continues for a certain period of time.

[0038] After step S6, the ECU 100 determines whether the shift position acquired in step S2 is any one of the D range, B range, and R range, and whether the counter B is greater than a predetermined value β (step S8). If the result in step S8 is No, this control ends. If the result in step S8 is Yes, assuming that the hybrid vehicle 10 will start in a short time, the ECU 100 starts the engine 200 via the first clutch 210 by the motor 220 and shifts from the EV mode to the HV mode (step S9). Step S9 is an example of the process executed by the engine control unit. Since the engine 200 can be started by the motor 22 in the stopped state and shifted to the HV mode in this way, the jerk at the start of the hybrid vehicle 10 is suppressed.

[0039] In the example of FIG. 3, the ECU 100 acquired the gradient and vehicle speed before calculating the threshold value A, but the present invention is not limited to this, and it may be acquired before step S5 is executed. Further, in the example of FIG. 3, the ECU 100 acquired the shift position before the counter B was incremented or reset, but the present invention is not limited to this, and it may be acquired before step S8.

[0040] [Shift from HV mode to EV mode] By the way, in order to improve the fuel efficiency of the hybrid vehicle 10, it is effective to reduce the number of starts of the engine 200. In other words, it is effective to increase the area where the shift to the EV mode is possible.

[0041] FIG. 6 is a timing chart showing an example of the shift from the HV mode to the EV mode. FIG. 6 corresponds to FIG. 2. FIG. 6 shows a case where the driving mode is the HV mode, the shift position is in the drive range, the vehicle is traveling on an uphill slope where the gradient is equal to or greater than the threshold value A, and the battery 310 is at a low temperature. The HV mode is a state in which the first clutch 210 is engaged, the second clutch 230 is engaged, and the vehicle is traveling by at least the power of the engine 200. In the example of FIG. 6, a state of traveling only by the power of the engine 200 is shown.

[0042] The gradient gradually decreases and becomes equal to or less than a threshold value a (described later) at time t11. At time t12 after a predetermined time has elapsed in this state, the engine 200 is subjected to stop control, the torque of the engine 200 decreases, and the torque of the motor 220 increases. When the torque of the engine 200 decreases to zero at time t13, the first clutch 210 is disengaged, and the engine speed begins to decrease until it reaches zero. In contrast, the torque of the motor 220 is kept constant. When the depression amount of the accelerator pedal decreases at time t14, the rotational speed of the motor 220 and the input rotational speed of the transmission 240 begin to decrease, and the vehicle stops at time t15. Also, even if the vehicle starts again later, as long as the gradient is less than the threshold value A as shown in FIG. 3, the shift to the HV mode is not performed.

[0043] FIG. 7 is a flowchart showing an example of shift control from the HV mode to the EV mode executed by the ECU 100. The control of FIG. 7 is repeatedly executed. The ECU 100 determines whether the driving mode is the HV mode (step S11). If the answer is No in step S11, this control is terminated.

[0044] If the answer is Yes in step S11, the ECU 100 acquires the remaining amount and temperature of the battery 310, the gradient of the driving road surface, and the shift position (step S12). Step S12 is an example of the process executed by the second acquisition unit. Also, the remaining amount and temperature of the battery 310 and the gradient acquired by the ECU 100 in step S12 correspond to the second remaining amount, the second temperature, and the second gradient, respectively.

[0045] Next, the ECU 100 calculates a power value that can be output by the battery 310 based on the remaining amount and temperature of the battery 310 (step S13). The calculation method in step S13 is the same as that in step S3 described above.

[0046] Next, the ECU 100 calculates a threshold value a based on the power value that can be output by the battery 310 (step S14). Specifically, the ECU 100 calculates the threshold value a with reference to the map of FIG. 5 described above. The threshold value a is the upper limit value of the gradient that can be traveled in the EV mode. Similar to the threshold value A, the threshold value a increases as the outputtable power value increases, but is a value smaller than the threshold value A. This can prevent hunting between the EV mode and the HV mode. Steps S13 and S14 are examples of the processes executed by the second calculation unit. The threshold value a is an example of the second threshold value.

[0047] Next, the ECU 100 determines whether or not the gradient acquired in step S12 is less than or equal to the threshold value a (step S15). Step S15 is an example of the process executed by the second determination unit.

[0048] If Yes in step S15, the ECU 100 increments the counter C (step S16). If No in step S15, the ECU 100 resets the counter C (step S17). The counter C is a counter for determining whether or not the state determined as Yes in step S15 continues for a certain period of time.

[0049] After step S16, the ECU 100 determines whether the shift position acquired in step S12 is in the P range or the counter C is greater than a predetermined value γ (step S18). If No in step S18, this control ends. If Yes in step S18, the engine 200 is stopped, the first clutch 210 is released, the motor 220 is started, and the driving mode is shifted to the EV mode (step S19). Step S19 is an example of the process executed by the engine control unit.

[0050] In this way, by securing the driving range in the EV mode, the fuel efficiency can be improved. Also, since the vehicle shifts from the HV mode to the EV mode even when the shift position is in the P range, the fuel efficiency is improved.

[0051] In the example of FIG. 7, the ECU 100 obtains the gradient before calculating the threshold value a, but the present invention is not limited to this, and it may be obtained before step S15 is executed. Further, in the example of FIG. 7, the ECU 100 obtains the shift position before the counter C counts up or resets, but the present invention is not limited to this, and it may be obtained before step S18.

[0052] In this embodiment, the case where a hybrid vehicle is controlled by a single ECU 100 is illustrated, but the present invention is not limited to this. For example, the above-described control may be executed by a plurality of ECUs such as an engine ECU that controls the engine 200, a motor ECU that controls the motor 220, a clutch ECU that controls the first clutch, and a battery ECU that controls the battery 310.

[0053] As described above, the embodiments of the present invention have been described in detail. However, 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

[0054] 10 Hybrid vehicle 100 ECU (control device, first and second acquisition units, first and second calculation units, first and second determination units, engine control unit) 200 Engine 210 First clutch 220 Motor 230 Second clutch 240 Transmission 300 Power conversion device 310 Battery 510 SOC sensor 520 Temperature sensor 530 Gradient sensor 540 Vehicle speed sensor 550 Shift position sensor

Claims

1. An apparatus for controlling a hybrid vehicle having an engine, a motor provided in a power transmission path between the engine and drive wheels, and a battery for outputting power to the motor, the apparatus being applicable to the hybrid vehicle and being configured to be shiftable from an EV mode in which the motor is used as a driving power source without using the engine to an HV mode in which at least the engine is used as a driving power source by starting the engine with the motor, the apparatus including a first acquisition unit configured to acquire a first gradient of a road surface on which the hybrid vehicle is located in the EV mode, a first remaining amount of the battery, and a first temperature of the battery; a first calculation unit configured to calculate a first threshold value, which is a lower limit value of a gradient at which output power of the battery is insufficient to start the engine while starting the hybrid vehicle with the motor based on the first remaining amount and the first temperature; a first determination unit configured to determine whether the first gradient is greater than or equal to the first threshold value; an engine control unit configured to start the engine before starting when the hybrid vehicle is stopped and shift from the EV mode to the HV mode when the first gradient is greater than or equal to the first threshold value; and wherein the first calculation unit calculates the first threshold value to be smaller as the first temperature is lower; wherein the first calculation unit calculates the first threshold value to be smaller as the first remaining amount is smaller; a second acquisition unit configured to acquire a second gradient of a road surface on which the hybrid vehicle is located in the HV mode, a second remaining amount of the battery, and a second temperature of the battery; a second calculation unit configured to calculate a second threshold value, which is an upper limit value of a gradient on which the vehicle can travel in the EV mode based on the second remaining amount and the second temperature; a second determination unit configured to determine whether the second gradient is less than or equal to the second threshold value; and wherein the engine control unit stops the engine and shifts from the HV mode to the EV mode when the second gradient is less than or equal to the second threshold value; wherein the second calculation unit calculates the second threshold value to be smaller as the second temperature is lower; wherein the second calculation unit calculates the second threshold value to be smaller as the second remaining amount is smaller; wherein the first calculation unit calculates a first power value that can be output by the battery such that the first power value increases as the first remaining amount increases, calculates a first temperature correction coefficient that decreases from 1 as the first temperature is lower and decreases as the first remaining amount is smaller, and calculates the first threshold value to be smaller as a value obtained by multiplying the first temperature correction coefficient by the first power value is smaller. The second calculation unit calculates a second power value that can be output by the battery so as to increase as the second remaining amount increases, calculates a second temperature correction coefficient that decreases from 1 as the second temperature decreases and decreases as the second remaining amount decreases, and calculates the second threshold value to be smaller as the value obtained by multiplying the second temperature correction coefficient by the second power value is smaller. A control device for a hybrid vehicle, wherein when the value obtained by multiplying the first temperature correction coefficient by the first power value is the same as the value obtained by multiplying the second temperature correction coefficient by the second power value, the second threshold value is smaller than the first threshold value.

2. The first acquisition unit acquires a shift position. The engine control unit starts the engine before starting and shifts to the HV mode when the hybrid vehicle is stopped, if the first gradient is greater than or equal to the first threshold value and the shift position is in any of the drive range, brake range, and reverse range. The control device for a hybrid vehicle according to claim 1.

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