Control method for a hybrid vehicle and hybrid vehicle

Abstract

A hybrid vehicle has a motor as a drive source, a battery that supplies electric power to the motor, and an engine that can drive a generator to supply electric power to the battery, wherein in a case where a parameter that is larger the longer the engine operates, and in a case where the parameter is larger than a forced operation threshold value in a case where a value of the parameter is lower than the forced operation threshold value, the engine is caused to operate in a case where a size of background noise exceeds a noise threshold value.

Description

Technical Field

[0001] This invention relates to a control method for hybrid vehicles and to hybrid vehicles themselves. Background Technology

[0002] JP2013-56613A discloses a method for operating the engine of a hybrid vehicle equipped with an engine and an electric motor. According to this method, considering road noise generated between the wheels and the road surface during driving, the engine is activated when the background noise caused by road noise is high, and not activated when the background noise is low. By performing this operation control, the driver is less likely to notice the engine noise inside the vehicle due to background noise, thus improving the comfort of the vehicle interior. Summary of the Invention

[0003] In hybrid vehicles, in addition to background noise, the engine operates based on various parameters such as battery charge and catalyst temperature in the exhaust system. Therefore, the engine may operate even in situations with low background noise. If the engine operates in a cabin with low background noise, the comfort of the cabin may be compromised.

[0004] The purpose of this invention is to increase the opportunities for the engine to operate while keeping background noise low, thereby improving the comfort of the vehicle interior.

[0005] According to a certain aspect of the present invention, the control method for a hybrid vehicle includes a motor as a drive source, a battery that supplies power to the motor, and an engine that can drive a generator to supply power to the battery. The method further includes actions such as causing the engine to perform an action when the value of a parameter that increases with the length of the engine's operating time is below a forced action threshold, and causing the engine to perform an action when the background noise level exceeds a noise threshold. Attached Figure Description

[0006] Figure 1 This is a block diagram illustrating the structure of the hybrid vehicle involved in each implementation.

[0007] Figure 2 This is a flowchart illustrating the engine operation control according to the first embodiment.

[0008] Figure 3 It is a timing diagram that represents the operating status of vehicles in a comparative proportion.

[0009] Figure 4 This is a timing diagram showing the operating state of the vehicle according to the first embodiment.

[0010] Figure 5 This is a flowchart illustrating the engine operation control according to the second embodiment.

[0011] Figure 6 This is a flowchart illustrating the engine operation control according to the third embodiment.

[0012] Figure 7 This is a flowchart illustrating the engine operation control according to the fourth embodiment.

[0013] Figure 8 This is a flowchart representing the control of changing the upper limit of background noise control. Detailed Implementation

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings and other figures.

[0015] (First Embodiment)

[0016] Figure 1 This is a block diagram illustrating the structure of a hybrid vehicle according to the first embodiment of the present invention. Furthermore, this embodiment describes a series hybrid vehicle, but is not limited thereto. It can be a parallel hybrid vehicle, or a hybrid vehicle using both series and parallel configurations. Additionally, it can be a plug-in hybrid vehicle.

[0017] like Figure 1 As shown, vehicle 100 includes an engine (internal combustion engine) 1, a generator 2, a battery 3, an electric motor 4, gears 5, axles 6, and wheels 7. Furthermore, vehicle 100 is a series hybrid vehicle, with engine 1, generator 2, and electric motor 4 connected in series. That is, the power from engine 1 is not used to drive the wheels 7, but rather to power generator 2.

[0018] In detail, engine 1 is mechanically connected to generator 2 via a reducer (not shown), and generator 2 is connected to battery 3 and motor 4 in a manner capable of transmitting and receiving electricity. In this configuration, the rotational driving force of engine 1 is transmitted to generator 2, which generates electricity using the driving force of engine 1. Furthermore, the electricity generated in generator 2 is used to charge battery 3 and / or drive the rotation of motor 4. Additionally, electricity is supplied to motor 4 using generator 2 and / or battery 3.

[0019] Motor 4 is mechanically connected to axle 6 via gear 5, and axle 6 is mechanically connected to wheel 7. The driving force of motor 4 is transmitted to wheel 7 via gear 5 and axle 6. Wheel 7 rotates using the driving force of motor 4, thereby making vehicle 100 move.

[0020] Furthermore, a friction brake 8 is provided on the wheel 7. The friction brake 8 generates friction on the wheel 7 to provide braking force. Therefore, in the vehicle 100, in addition to the regenerative braking of the motor 4, friction braking by the friction brake 8 can also be performed.

[0021] The vehicle 100 has a controller 10 that controls the entire system. Furthermore, the vehicle 100 also includes: a brake hydraulic pressure sensor 21 that detects braking force; an accelerator position sensor 22 that detects accelerator opening; a wheel speed sensor 23 that measures the rotational speed of the wheels 7; a first temperature sensor 24 and a second temperature sensor 25 that acquire parameters related to the engine 1; and a pressure sensor 26 that acquires parameters related to the friction brake 8. The controller 10 is electrically connected to each of the aforementioned sensors and receives the detection results.

[0022] Here, the wheel speed sensor 23 is positioned on one side of the wheel 7, which is lower than the suspension, and can measure the rotational speed of the wheel 7 near the wheel 7. The rotational speed of the wheel 7 detected by the wheel speed sensor 23 is used to determine the speed of the vehicle 100, and, as described later, can be used to infer road noise generated between the wheel 7 and the road surface during driving.

[0023] A first temperature sensor 24, installed in engine 1, measures the temperature of the catalyst installed in the exhaust system (exhaust path) of engine 1. Additionally, a second temperature sensor 25, installed in the water-cooling system of engine 1, measures the temperature of the cooling water, which serves as the refrigerant. Furthermore, this embodiment describes an example where the temperature of the catalyst in the exhaust system is obtained by the first temperature sensor 24, but it is not limited to this. The catalyst temperature can also be estimated based on factors such as the operating point of engine 1.

[0024] The friction brake 8 has a brake booster (master-back) that is subjected to negative pressure. When the brake pedal is depressed, the negative pressure of the brake booster can generate greater friction braking even with a small depressing force. The negative pressure of the brake booster is generated by the rotation of the engine 1 and is obtained by the pressure sensor 26.

[0025] The controller 10 in the vehicle 100 mainly includes: a motor controller 11, which controls the motor 4; a battery controller 12, which monitors the status of the battery 3; an engine controller 13, which controls the engine 1; and a navigation controller 14, which sets the route.

[0026] The motor controller 11 generates a torque command value based on inputs from the brake hydraulic pressure sensor 21 and the accelerator position sensor 22, in a manner that ensures the rotational speed of the wheel 7, as obtained by the wheel speed sensor 23, reaches the target rotational speed. The generated torque command value is then output to the motor 4. Thus, the motor 4 is able to generate the desired torque.

[0027] The battery controller 12 is configured to acquire the voltage and current of the battery 3 and monitor the state of charge (SOC) of the battery 3. Furthermore, the percentage of electrical charge applied to the battery 3 (charge rate) will be referred to solely as SOC below.

[0028] The engine controller 13 causes the engine 1 to perform actions and controls the output of the generator 2, thereby controlling the state of charge (SOC) of the battery 3. The timing of the engine 1's operation based on the engine controller 13 is determined according to the operating parameters described later.

[0029] Here, below, the sounds other than the engine 1's operating sound that can be heard by the driver (and other passengers) inside the vehicle cabin while driving are referred to as background noise. Additionally, road noise generated between the wheels 7 and the road surface during vehicle operation is the main component of background noise. When the background noise is extremely high, the engine 1's operating sound is not easily noticed by the driver inside the vehicle cabin. Therefore, the engine controller 13 activates the engine 1 when the background noise is extremely high, thereby enabling the engine 1 to operate without the driver noticing. Furthermore, in this embodiment, the engine controller 13 controls the operation of the engine 1 based on the magnitude of the background noise when the operating parameters are predetermined.

[0030] Furthermore, as an example, the engine controller 13 acquires the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23, and calculates the road noise generated between the wheel 7 and the road surface when the vehicle 100 is moving. For example, the engine controller 13 differentiates the acquired angular velocity ω of the wheel 7 to obtain the angular acceleration A of the wheel 7, calculates the fluctuation of the acquired angular acceleration A, and infers the magnitude of the road noise based on this fluctuation. The engine controller 13 determines that the larger the fluctuation of angular acceleration A, the greater the road noise, and the smaller the fluctuation of angular acceleration A, the smaller the road noise. In this way, the engine controller 13 calculates the road noise based on the angular velocity ω of the wheel 7 acquired by the wheel speed sensor 23, and infers the magnitude of the background noise based on the road noise. In addition, a microphone can be installed in the vehicle interior, and the engine controller 13 infers the background noise based on the sound collection results of the microphone.

[0031] The navigation controller 14 includes a GPS receiver (not shown), a communication interface, and a map database, and has a navigation function that sets the driving route based on the driver's operation. The navigation controller 14 is configured to acquire congestion information and determine whether congestion has occurred along the driving route.

[0032] Furthermore, the controller 10 is composed of a computer having a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface). Alternatively, the controller 10 can be configured as a single device, or it can be divided into multiple modules, with each module performing the various processes of this embodiment in a distributed manner. Additionally, the processes shown in the flowcharts described later are performed by executing the program stored in the controller 10.

[0033] Figure 2 This is a flowchart illustrating the engine motion control executed by the engine controller 13. This engine motion control is executed repeatedly. Furthermore, based on the engine motion control shown in this diagram, the engine controller 13 causes the engine 1 to perform actions when the background noise level is extremely high.

[0034] exist Figure 2 In the processing, motion parameters are used to control the motion of engine 1. These motion parameters increase with the longer the motion time of engine 1. Furthermore, the motion parameters have an appropriate numerical range; when the values ​​fall below a mandatory motion threshold within this range, engine 1 begins to move, thereby increasing the motion parameters. Additionally, after engine 1 moves, if the motion parameters exceed a stop threshold, engine 1 is stopped.

[0035] The operating parameters include, for example, the catalyst temperature of the exhaust system of engine 1, which is obtained by the first temperature sensor 24. In this embodiment, an example where the operating parameter is the catalyst temperature will be described. Other examples of operating parameters are shown in embodiments 5 to 7 described later, such as the coolant temperature of the water cooling system of engine 1 (5th embodiment), the SOC of battery 3 (6th embodiment), which is obtained by the second temperature sensor 25, and the brake booster negative pressure of friction brake 8 (7th embodiment), which is obtained by the pressure sensor 26.

[0036] In step S101, the engine controller 13 determines whether the catalyst temperature, which is an action parameter, is greater than or equal to a stop threshold. If the catalyst temperature is determined to be greater than or equal to the stop threshold (S101: Yes), the engine controller 13 determines that the catalyst temperature is high enough that the engine 1 does not need to perform any action, and ends the engine action control. On the other hand, if the catalyst temperature is determined to be lower than the stop threshold (S101: No), the engine controller 13 proceeds to step S102 to further determine whether the engine 1 needs to perform any action.

[0037] In step S102, the engine controller 13 determines whether the catalyst temperature falls within a range that is less than the background noise control upper limit and greater than or equal to the forced action threshold. The background noise control upper limit is a value that is less than the stop threshold and greater than the forced action threshold. The forced action threshold is the lower limit temperature of activity; when the catalyst temperature is below the forced action temperature, engine 1 is controlled to operate. Moreover, as described later, even when the catalyst temperature exceeds the forced action temperature, engine 1 is controlled to operate even when the background noise is high. The background noise control upper limit represents the upper limit of the catalyst temperature at which engine 1 is controlled to operate in accordance with this background noise. If it is determined that the catalyst temperature falls within this range (S102: Yes), the engine controller 13 proceeds to step S103 to further determine whether engine 1 operation corresponding to the background noise is required.

[0038] On the other hand, if it is determined that the catalyst temperature is not included in the value range (S102: No), the engine controller 13 determines that it is not necessary to determine whether the engine 1 needs to operate in accordance with the background noise. In order to further determine whether the engine 1 needs to operate in accordance with the catalyst temperature, the next step is to proceed with the processing of step S110.

[0039] In step S103, the engine controller 13 calculates the background noise using the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23. As described above, for example, the engine controller 13 estimates the magnitude of the background noise caused by road noise based on the fluctuation of the angular acceleration A, which is the derivative of the angular velocity ω. Furthermore, not limited to this method, the engine controller 13 may also obtain the magnitude of the background noise using other methods.

[0040] Furthermore, the engine controller 13 uses a threshold to determine background noise at two levels. Specifically, the engine controller 13 determines the background noise to be at a high level when the background noise is greater than the threshold, and at a low level when the background noise is less than the threshold.

[0041] In step S104, the engine controller 13 determines whether the background noise level is high. If the background noise level is high (S104: Yes), the engine controller 13 proceeds to step S105 to enable the engine 1 to perform an operation. On the other hand, if the background noise level is not high (S104: No), the engine controller 13 determines that the condition is not suitable for enabling the engine 1 to perform an operation and terminates engine operation control.

[0042] In step S105, the engine controller 13 causes the engine 1 to operate. Through this control, the engine 1 operates even when the catalyst temperature is above the forced operation threshold (lower activity limit temperature) and when the background noise is high (S104: Yes) (S105). As a result, the catalyst temperature is raised to allow the engine 1 to operate in a state where the sound of the engine 1 is difficult for the driver to notice, thus maintaining cabin comfort and keeping the catalyst temperature above the lower activity limit temperature.

[0043] In step S106, the engine controller 13 determines whether the catalyst temperature is greater than or equal to a stop threshold. If the catalyst temperature is determined to be greater than or equal to the stop threshold (S106: Yes), the engine controller 13 determines that the catalyst temperature is high enough that the engine 1 does not need to perform any action, and proceeds to step S107 to stop the engine 1. On the other hand, if the catalyst temperature is determined to be lower than the stop threshold (S106: No), the engine controller 13 proceeds to step S109 to further determine whether the engine 1 needs to be stopped.

[0044] In step S107, the engine controller 13 stops the engine 1. That is, when the catalyst temperature exceeds the stop threshold by causing the engine 1 to perform an action (S107: Yes), the catalyst temperature becomes high enough to stop the engine 1 (S107).

[0045] In step S108, similar to step S103, the engine controller 13 uses the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23 to calculate the background noise and determines the magnitude of the background noise in two levels.

[0046] In step S109, the engine controller 13 determines whether the background noise is low. If the background noise is low (S109: Yes), the engine controller 13 determines that the engine 1's operating sound is likely to be audible to the driver inside the vehicle. To stop the engine 1, the process proceeds to step S107. On the other hand, if the background noise is not low (S104: No), the engine controller 13 determines that the engine 1's operating sound is difficult for the driver to hear and the engine 1 can continue operating. Next, the process returns to step S106, and the engine 1 continues operating.

[0047] Thus, in the processes of steps S103 to S109, even when the catalyst temperature exceeds the forced operation threshold (lower activity limit temperature) (S102: Yes) and the background noise level is high (S204: Yes), the engine controller 13 still causes the engine 1 to operate (S105). As a result, the chance of the engine 1 operating when the driver is unlikely to notice the sound of the engine 1 operating due to background noise increases, thus ensuring the comfort of the vehicle interior and maintaining a high catalyst temperature, thereby reducing the possibility of the catalyst temperature falling below the forced operation threshold (lower activity limit temperature).

[0048] On the other hand, in step S110, the engine controller 13 determines whether the catalyst temperature is lower than the forced action threshold. If the catalyst temperature is lower than the forced action threshold (S110: Yes), the engine controller 13 determines that the engine 1 needs to be activated in order to increase the catalyst temperature, and then proceeds to step S111.

[0049] In step S111, the engine controller 13 causes the engine 1 to perform an action.

[0050] In step S112, the same process as in step S106 is performed. That is, the engine controller 13 determines whether the catalyst temperature is greater than or equal to a stop threshold. If it is determined that the catalyst temperature is greater than or equal to the stop threshold (S112: Yes), the engine controller 13 proceeds to the process of step S113. On the other hand, if it is determined that the catalyst temperature is lower than the stop threshold (S112: No), the engine controller 13 continues to perform the process of step S112.

[0051] In step S113, the engine controller 13 stops the engine 1. This causes the engine 1 to operate when the catalyst temperature is below the forced operation threshold, thus increasing the catalyst temperature to the stop threshold.

[0052] Furthermore, in this embodiment, a value lower than the stop threshold is used as the upper limit for background noise control. This is to suppress the continuous repetition of processes between the process of causing the engine 1 to operate when the catalyst temperature is lower than the upper limit for background noise control (S102: Yes) (S105) and the process of causing the engine 1 to stop when the catalyst temperature is greater than or equal to the stop threshold (S101: Yes) (S106).

[0053] For example, if the same value as the stop threshold is used for the background noise control upper limit, the following process may be performed. If the catalyst temperature is slightly below the stop threshold (S101: No, S102: Yes), after engine 1 operates (S105), the catalyst temperature immediately exceeds the stop threshold (S106: Yes), causing engine 1 to stop (S107). Such a short-term stop after engine 1 operation is undesirable. Therefore, by setting the background noise control upper limit to a value lower than the stop threshold, the repeated operation and stopping of engine 1 can be suppressed.

[0054] Furthermore, repeated processing as described above may occur, but the same value as the stop threshold can be used as the upper limit for background noise control. Even if the same value as the stop threshold is used as the upper limit for background noise control, when the catalyst temperature is between the stop threshold and the forced action threshold (S102: Yes), the operation control of engine 1 corresponding to the level of background noise can be performed through the processing of steps S103 to S109.

[0055] Figure 2 The summary of engine motion control is shown in the table below.

[0056] [Table 1]

[0057]

[0058] In this table, the background noise level is indicated by two levels of size in the column direction, and three conditions corresponding to the catalyst temperature are shown in the row direction. In the row direction, the first row shows the case where the catalyst temperature is greater than or equal to the stop threshold (S101: Yes), the second row shows the case where the catalyst temperature is less than the stop threshold and greater than or equal to the upper limit of the background noise control value, the third row shows the case where the catalyst temperature is less than the upper limit of the background noise control value and greater than or equal to the forced action threshold (S101: No, S102: Yes), and the fourth row shows the case where the catalyst temperature is less than the forced action threshold (S101: No, S102: No, S110: Yes).

[0059] When the catalyst temperature exceeds the stop threshold, as shown in line 1, engine 1 is not activated, and therefore no engine 1 operation control corresponding to the background noise level is generated. Similarly, line 2 shows the case where the catalyst temperature is below the stop threshold but greater than or equal to the upper limit of the background noise control. When the catalyst temperature is within this range, according to... Figure 2 The engine 1 is not activated by the three decision processes (S101: No, S102: No, S110: No), so the same process as the case shown in the first line where the catalyst temperature is greater than or equal to the stop threshold (S101: Yes) is performed.

[0060] Furthermore, when the catalyst temperature shown in line 4 is below the forced action threshold (lower activity limit temperature), engine 1 does not perform actions according to the noise level, and therefore no action control of engine 1 corresponding to the background noise level is generated.

[0061] On the other hand, referring to line 3, when the catalyst temperature is less than the upper limit of the background noise control and greater than or equal to the forced action threshold (S101: No, S102: Yes), the operation method of engine 1 varies depending on the level of background noise. That is, when the background noise is at a high level (S104: Yes), engine 1 performs the action (S105). On the other hand, when the background noise is at a low level (S104: No), engine 1 does not perform the action.

[0062] In this way, even if the catalyst temperature exceeds the forced activation threshold (lower activity limit temperature), the engine 1 will still operate under high background noise levels. Therefore, in a state where the driver is unlikely to notice the engine 1's operation, the catalyst temperature can be increased by the engine 1's operation, thus maintaining the catalyst temperature above the lower activity limit temperature. On the other hand, when the background noise level is low, the driver can easily notice the engine 1's operation, thus improving cabin comfort by suppressing the engine 1's operation.

[0063] use Figure 3 and 4 The effects obtained through this embodiment will be explained.

[0064] Figure 3 This is a timing diagram showing the states of a comparative hybrid vehicle. From top to bottom, the diagram displays (a) vehicle speed, (b) catalyst temperature, (c) coolant temperature, (d) state of charge (SOC), (e) road surface level, (f) background noise level, and (g) engine speed. Furthermore, (e) road surface level and (f) background noise level are represented by three levels in this diagram.

[0065] In this example, engine 1 is activated when (f) the background noise level is at its maximum. Furthermore, engine 1 is activated when (b) the catalyst temperature, (c) the coolant temperature, and (d) the state of charge (SOC) are all below the forced activation threshold; if these parameters are sufficiently high, engine 1 is stopped. Moreover, (g) engine 1's operation is not controlled based on (a) vehicle speed.

[0066] The control at times t1 to t3 is explained. At time t1, if (e) the road surface condition is poor, then (f) the background noise level increases. Furthermore, at time t2, if (e) the road surface condition is even worse, then (f) the background noise level reaches its maximum, and (g) engine 1 begins operation, causing the engine speed to increase. Then, at time t3, if (e) the road surface condition improves, then (f) the background noise level decreases, causing (g) engine 1 to stop, causing the engine speed to drop to zero. Here, during times t2 to t3, engine 1 is operated, therefore (b) the catalyst temperature, (c) the coolant temperature, and (d) the state of charge (SOC) all increase.

[0067] Next, the control at times t4 to t5 will be explained. At time t4, if (e) the road surface condition worsens, then (f) the background noise increases, but does not reach its maximum level. Moreover, at time t5, if (e) the road surface condition improves, then (f) the background noise level decreases. Since (f) the background noise does not reach its maximum level between times t4 and t5, engine 1 is not activated (g).

[0068] Next, the control at times t6 to t7 will be explained. At time t6, if (b) the catalyst temperature is lower than the catalyst's lower activity limit temperature (forced action threshold), then (g) engine 1 will perform an action regardless of (f) background noise. Then, at time t7, if (b) the catalyst temperature is sufficiently high, then (g) engine 1 will be stopped.

[0069] Next, the control at times t8 to t9 will be explained. At time t8, if (d) the SOC is lower than the lower limit of the operating range (forced action threshold), then (g) engine 1 will perform an action regardless of (f) background noise. Then, at time t9, if (b) the SOC is sufficiently large, then (g) engine 1 will stop.

[0070] Next, the control at times t10 to t13 will be explained. Compared to the actions at times t1 to t3, at time t3, (e) the background noise level decreases by one level; conversely, (e) the background noise level decreases by two levels at times t12 and t13. At time t12, (e) the background noise does not reach its maximum level, therefore (g) engine 1 is stopped. As a result, at times t11 to t12 when (g) engine 1 is activated, (b) the catalyst temperature, (c) the coolant temperature, and (d) the state of charge (SOC) increase.

[0071] Next, the control at times t14 to t15 will be explained. At time t14, if (c) the coolant temperature is lower than the mandatory action threshold of the heating request level range, then (g) engine 1 will perform an action. Then, at time t15, if (c) the coolant temperature is high enough, then (g) engine 1 will stop.

[0072] Thus, in addition to (f) the times when the background noise level becomes the maximum level (t2-t3) and (t11-t12), (g) the operation period of engine 1 also includes (b) the times when the catalyst temperature is lower than the lower limit of the active temperature (forced operation threshold) causing engine 1 to start operating, (d) the times when the SOC is lower than the lower limit of the operating range (forced operation threshold) causing engine 1 to start operating, and (c) the times when the coolant temperature is lower than the lower limit of the heating request (forced operation threshold) causing engine 1 to start operating.

[0073] In this comparative example, if the background noise level becomes the maximum in (e), and the catalyst temperature, coolant temperature, and SOC are all below the forced action threshold, the engine 1 will not be activated based on the background noise in (d), which may compromise the comfort of the vehicle interior.

[0074] Next, the operation of the hybrid vehicle 100 of this embodiment will be described.

[0075] Figure 4 This is a timing diagram showing the state of the hybrid vehicle 100 according to this embodiment. In this diagram, from top to bottom, (a) vehicle speed, (b) catalyst temperature, (e) road surface grade, (f) background noise level, and (g) engine speed are shown. However, (c) coolant temperature and (d) state of charge (SOC) are omitted from this diagram. Furthermore, in this embodiment, with... Figure 3 Similarly, in the comparative example, engine 1 is operated even when the background noise level (f) is at its maximum. Furthermore, catalyst temperature (b) is used as an operating parameter. Figure 2 The engine motion control is shown.

[0076] First, the control at times t1 to t3 will be explained. At times t1 to t3, [the process] will involve... Figure 3 The same processing is applied to the time intervals t1 to t3 in the comparative example. At the time intervals t2 to t3 when the background noise level is the highest (f), engine 1 is made to perform an action.

[0077] Next, the control at times t4 to t7 will be explained. At time t4, if (e) the road surface grade is poor, then (f) the background noise level increases. In this case, (f) the background noise exceeds the level used for... Figure 2 The threshold for the two levels of grading in step S103.

[0078] Furthermore, at time t5, if the catalyst temperature exceeds the upper limit of the background noise control, engine 1 is controlled according to the background noise level. At time t5, the background noise level is relatively high, therefore engine 1 (g) is activated. Then, at time t6, if the catalyst temperature (b) reaches the stop threshold, engine 1 (g) is stopped.

[0079] Next, the control at times t8 to t11 will be explained. During times t8 to t11, [the process] will be performed in conjunction with... Figure 3 The same treatment is applied at times t10 to t13 in the comparative example. That is, at times t9 to t10 when the noise level is at its maximum (e), engine 1 is activated (g), and the catalyst temperature increases (b).

[0080] In this way, by using only one operating parameter (catalyst temperature) based on the background noise level at its maximum, the chances of engine 1 operating can be reduced. Furthermore, even when the operating parameter is not lower than the forced operating threshold, engine 1 will still operate at a high background noise level to avoid compromising cabin comfort. As a result, the chances of increasing the operating parameter increase, thus suppressing engine 1 operation at lower background noise levels and improving cabin comfort.

[0081] According to the first embodiment, the following effects can be obtained.

[0082] According to the control method of the hybrid vehicle 100 in the first embodiment, an operating parameter whose value increases accordingly with the operating time of the engine 1 is adopted. When the operating parameter is lower than the forced operating threshold (S101: No, S102: No, S110: Yes), the engine 1 is made to perform an operation (S111).

[0083] Furthermore, when the action parameters exceed the forced action threshold (S101: No, S102: Yes), the operation of engine 1 is controlled according to the magnitude of the background noise. Specifically, when the magnitude of the background noise exceeds the threshold by a large level (S104: Yes), engine 1 is made to perform an action (S105).

[0084] By implementing this control, engine 1 can be made to operate even when the background noise is high and the forced action threshold is exceeded. Therefore, the action parameters can be increased when the driver is unlikely to notice the engine 1's operation, thus maintaining the action parameters above the forced action threshold. On the other hand, when the background noise is low, the driver is more likely to notice the engine 1's operation. Therefore, by suppressing the engine 1's operation, the comfort inside the vehicle can be improved.

[0085] According to the control method of the hybrid vehicle 100 in the first embodiment, if the operating parameter further exceeds the stop threshold (S106: Yes), the engine 1 is stopped (S107). In this way, by limiting the operating time of the engine 1, it is possible to control the operating parameter to be within an appropriate numerical range.

[0086] According to the control method of the hybrid vehicle 100 in the first embodiment, when the operating parameter is less than the upper limit of the background noise control (which may be a stop threshold) and greater than the forced operation threshold, and when the level of the background noise is lower than the threshold and is at a low level (S109: Yes), the engine 1 is stopped (S107). When the background noise is low, the driver can easily notice the operating sound of the engine 1, so by suppressing the operation of the engine 1, the comfort of the vehicle interior can be improved.

[0087] According to the control method of the hybrid vehicle 100 in the first embodiment, the catalyst temperature of the exhaust system of the engine 1, acquired by the first temperature sensor 24, is used as the operating parameter. There exists a lower limit temperature for the catalyst to operate in an active state, and the catalyst temperature increases accordingly with the operating time of the engine 1. Therefore, in principle, when the catalyst temperature is below the lower limit temperature, the engine 1 is operated to increase the catalyst temperature. Furthermore, in this embodiment, even if the catalyst temperature is greater than or equal to the lower limit temperature, the engine 1 can be operated even with high background noise. Therefore, the operating parameter can be increased when the driver is less likely to notice the engine 1's operation sound, resulting in an overall ease in maintaining the operating parameter above the forced operation threshold. On the other hand, when the background noise is low, the driver is more likely to notice the engine 1's operation sound; therefore, by suppressing the engine 1's operation, the comfort inside the vehicle can be improved.

[0088] (Second Implementation)

[0089] In the first embodiment, control of background noise levels based on two levels was described, but the method is not limited to this. In the second embodiment, control of background noise levels based on three levels was described.

[0090] Figure 5 This is a flowchart of the engine operation control according to the second embodiment. In this embodiment, it is related to... Figure 2 Compared to the engine operation control of the first embodiment shown, the processes of steps S201 to S206 and S207 are provided instead of the processes of steps S102 to S104 and S108.

[0091] First, the processing of steps S201 to S203 will be explained.

[0092] In step S201, the engine controller 13 determines whether the catalyst temperature (operation parameter) falls within a value range that is less than the stop threshold and greater than or equal to the background noise control upper limit. If the catalyst temperature is determined to fall within this value range (S201: Yes), the engine controller 13 proceeds to step S202 to further determine whether the engine 1 needs to operate in accordance with the background noise.

[0093] On the other hand, if it is determined that the catalyst temperature is not included in the value range (S201: No), the engine controller 13 will proceed to step S204 to further determine whether the engine 1 needs to be controlled in accordance with the background noise.

[0094] In step S202, the engine controller 13 uses the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23 to calculate the background noise, and uses two thresholds to determine the magnitude of the background noise in three levels: large, medium, and small.

[0095] In step S203, the engine controller 13 determines whether the background noise is at a high level. If the background noise is at a high level (S203: Yes), the engine controller 13 proceeds to step S105 to initiate engine 1's operation. On the other hand, if the background noise is not at a high level (S203: No), the engine controller 13 determines that it is not a condition for initiating engine 1's operation and terminates engine operation control. Thus, when the catalyst temperature is high, the necessity to increase the catalyst temperature is less, and therefore the engine 1 is initiated within a short time after the background noise becomes high.

[0096] Next, the processing of steps S204 to S206 will be explained.

[0097] In step S204, the engine controller 13 determines whether the catalyst temperature falls within a range that is less than the background noise control upper limit and greater than or equal to the forced action threshold. If the catalyst temperature is determined to fall within this range (S204: Yes), the engine controller 13 proceeds to step S205 to further determine whether the engine 1 needs to be activated in accordance with the background noise.

[0098] On the other hand, if it is determined that the catalyst temperature is not within the specified range (S204: No), the engine controller 13 will proceed to step S110 in order to perform further processing corresponding to the magnitude of the catalyst temperature.

[0099] In step S205, the same process as in step S202 is performed. The engine controller 13 determines the magnitude of the background noise in three levels.

[0100] In step S206, the engine controller 13 determines whether the background noise is at a high or medium level. If the background noise is at a high or medium level (S206: Yes), the engine controller 13 proceeds to step S105 to initiate engine 1 operation. On the other hand, if the background noise is not at a high or medium level but at a low level (S206: No), the engine controller 13 determines that it is not a condition for initiating engine 1 operation and terminates engine operation control. Thus, when the catalyst temperature is low, there is a greater need to increase the catalyst temperature, and therefore the engine 1 is initiated for a longer period of time while the background noise is at a high or medium level.

[0101] Furthermore, the smaller of the two thresholds used to determine the three levels of background noise in steps S202 and S205 can be the same as the threshold used for determining the two levels in the first embodiment. When the smaller threshold is the same as the threshold used for determining the two levels in the first embodiment, the condition for determining the background noise level that causes the engine 1 to operate is equivalent to the condition in step S105 of the first embodiment.

[0102] Furthermore, in step S207, similar to steps S202 and S205, the engine controller 13 calculates the background noise using the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23, and determines the magnitude of the background noise in three levels. By determining the background noise level in this way, processing corresponding to the background noise level can be performed in the subsequent step S109.

[0103] Figure 5 The summary of engine motion control is shown in the table below.

[0104] [Table 2]

[0105]

[0106] In this table, background noise levels are displayed in three columns, and four conditions corresponding to catalyst temperature are shown in the rows. Compared to Table 1 of the first embodiment, a medium level of background noise has been added to the second column. Furthermore, in the row direction, when the catalyst temperature shown in the second row is less than the upper limit value but greater than or equal to the upper limit value for background noise control, [the following conditions are also listed]. Figure 5 The processing shown corresponds to (S101: No, S201: Yes).

[0107] Referring to line 2, the catalyst temperature is greater than the upper limit of the background noise control and has a large margin, thus enabling engine 1 to operate within a short period of time when the background noise level becomes high. As a result, the catalyst temperature can be increased in a state where the sound of engine 1 operating is less noticeable to the driver.

[0108] On the other hand, referring to line 3, when the catalyst temperature is below the upper limit of the background noise control and has a small margin, the engine 1 is activated when the background noise level is greater than or equal to the medium level. In this case, the engine 1 is activated even when the background noise level is medium, so the sound of the engine 1 is easily noticeable to the driver, and the catalyst temperature can be increased more aggressively. Furthermore, suppressing the operation of the engine 1 when the background noise level is low can improve the comfort of the vehicle interior.

[0109] According to the second embodiment, the following effects can be obtained.

[0110] According to the control method of the hybrid vehicle 100 in the second embodiment, when the operating parameter (catalyst temperature) is less than the stop threshold and greater than the forced operation threshold, and when the operating parameter is large and exceeds the background noise control upper limit (S201: Yes), the background noise threshold for causing the engine 1 to operate is increased. As a result, when the background noise level is large (S203: Yes), the engine 1 operates (S105). On the other hand, when the operating parameter is small and lower than the background noise control upper limit (S201: No, S204: Yes), the background noise threshold for causing the engine 1 to operate is decreased. As a result, when the background noise level is high or medium (S206: Yes), the engine 1 operates (S105).

[0111] In this way, when the action parameters are large, there is less need to increase the action parameters. Therefore, the action conditions corresponding to the background noise are strictly defined. When the background noise is at a high level, the engine 1 performs the action, so that the action parameters can be kept above the forced action threshold when the driver can hardly notice the sound of the engine 1.

[0112] On the other hand, when the action parameters are relatively small, there is a greater need to increase them. Therefore, the action conditions corresponding to the background noise are specified more leniently, and the engine 1 is activated when the background noise is greater than or equal to a medium level. As a result, the driver can easily notice the sound of the engine 1 operating and is more proactive in activating it, thus maintaining the action parameters above the forced action threshold. At the same time, the engine 1's operation is suppressed when the background noise is low, thereby improving the comfort of the vehicle interior.

[0113] (Third Implementation)

[0114] In the first and second embodiments, it is determined whether the engine 1 needs to operate based on the background noise level. In the third embodiment, the control of changing the output of the engine 1 based on the background noise level is described.

[0115] Figure 6 This is a flowchart of the engine operation control according to the third embodiment. In this embodiment, [the following is mentioned:] ... Figure 2 Compared to the engine operation control of the first embodiment shown, the processes of steps S301 to S305 and S306 are provided instead of the processes of steps S103 to S105 and S108.

[0116] In step S301, the engine controller 13 calculates the background noise using the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23, and classifies the background noise into three levels: large, medium, and small. Furthermore, this judgment process is related to... Figure 5 Steps S202 and S205 of the second embodiment shown are the same.

[0117] In step S302, the engine controller 13 determines whether the background noise is at a high level. If the background noise is at a high level (S302: Yes), the engine controller 13 proceeds to step S303 to enable the engine 1 to perform an operation. On the other hand, if the background noise is not at a high level (S302: No), the engine controller 13 proceeds to step S304 to further determine whether the engine 1 needs to operate in accordance with the background noise.

[0118] In step S303, the engine controller 13 causes the engine 1 to perform an action with a larger output.

[0119] In step S304, the engine controller 13 determines whether the background noise is at a medium level. If the background noise is at a medium level (S304: Yes), the engine controller 13 proceeds to step S305 to enable the engine 1 to perform an action. On the other hand, if the background noise is not at a medium level (S304: No), the engine controller 13 determines that the state is not conducive to enabling the engine 1 to perform an action and terminates engine action control.

[0120] In step S305, the engine controller 13 causes the engine 1 to perform an action with a smaller output.

[0121] Furthermore, in step S306, similar to step S301, the engine controller 13 calculates the background noise using the angular velocity ω of the wheel 7 detected by the wheel speed sensor 23, and determines the magnitude of the background noise in three levels. This background noise level determination allows for processing corresponding to the background noise level in the subsequent step S109.

[0122] Therefore, when the catalyst temperature is below the upper limit of the background noise control but greater than or equal to the forced operation threshold (S101: No, S102: Yes), when the background noise is at a high level (S302: Yes), the engine 1 operates at high output (S303), and when the background noise is at a medium level (S304: Yes), the engine 1 operates at low output (S305). Thus, even if the engine 1 operates at high output and the operating noise increases when the background noise is high, the driver is unlikely to notice the operating noise, thus ensuring cabin comfort and increasing the catalyst temperature. On the other hand, when the background noise is at a medium level and low, the engine 1 operates at low output and the operating noise decreases, so the driver is unlikely to notice the operating noise, again ensuring cabin comfort and increasing the catalyst temperature.

[0123] Furthermore, the smaller of the two thresholds used for determining the three levels of background noise in step S301 can be the same as the threshold used for determining the two levels in the first embodiment. When the smaller threshold is the same as the threshold used for determining the two levels in the first embodiment, the condition for determining the background noise level that causes the engine 1 to perform the operation is the same as the condition for step S105 in the first embodiment. Additionally, the larger threshold is used for the determination in step S302, and therefore can be referred to as the output switching threshold for switching the output of the engine 1.

[0124] Figure 6 The summary of engine motion control is shown in the table below.

[0125] [Table 3]

[0126]

[0127] In this table, the background noise levels are shown in three levels in the column direction, similar to the second embodiment shown in Table 2, and in the row direction, the four conditions corresponding to the catalyst temperature (operational parameter) are shown in the first embodiment shown in Table 1.

[0128] Referring to line 3, when the catalyst temperature is below the upper limit of the background noise control and is greater than or equal to the stop threshold, if the background noise level is high (S302: Yes), the engine 1 is made to perform the operation at high output (S303), and if the background noise level is medium (S304: Yes), the engine 1 is made to perform the operation at low output (S305).

[0129] Therefore, in situations with high background noise, even if the engine 1 operates at high output, increasing the operating noise, it is difficult for the driver to notice. As a result, cabin comfort is ensured, and the operating parameters can be increased quickly by increasing output. On the other hand, in situations with low background noise, the engine 1 operates at low output, reducing the operating noise, which is difficult for the driver to notice. Therefore, cabin comfort can be maintained, and the catalyst temperature can be increased. As a result, it is easy to maintain the operating parameters above the forced operating threshold.

[0130] According to the third embodiment, the following effects can be obtained.

[0131] According to the control method of the hybrid vehicle 100 in the third embodiment, when the operating parameter is less than the background noise control upper limit (which may be equal to the upper limit) and greater than the forced operation threshold (S101: No, S102: Yes), and when the magnitude of the background noise exceeds a large output switching threshold and is at a high level (S302: Yes), the engine 1 is made to perform the operation at a high output (S303). On the other hand, when the magnitude of the background noise exceeds a small output switching threshold and is at a medium level (S304: Yes), the engine 1 is made to perform the operation at a low output (S305).

[0132] Therefore, by modifying the engine 1 so that its output increases with higher background noise, it is possible to ensure cabin comfort while appropriately increasing operating parameters. That is, even with high engine output in environments with high background noise, the driver is unlikely to notice, thus maintaining cabin comfort and keeping the catalyst temperature above or equal to the lower limit. On the other hand, with moderate background noise, the driver is more likely to notice the engine 1's operation; therefore, by suppressing engine 1's output, cabin comfort can be maintained while keeping the catalyst temperature above or equal to the lower limit.

[0133] (Fourth implementation)

[0134] In the fourth embodiment, other examples of stopping conditions for engine 1 will be further described.

[0135] Figure 7 This is a flowchart illustrating the engine operation control according to the fourth embodiment. According to this diagram, compared to the engine operation control of the first embodiment, step S109A is provided instead of step S109.

[0136] In step S109A, the additional hybrid vehicle 100 is not traveling on a congested route and the background noise level is low, or the hybrid vehicle 100 is traveling on a congested route and the vehicle speed is zero (parked). That is, the engine is stopped by the same determination process as in embodiments 1 to 3, except when in congestion, and the engine is stopped when the vehicle speed is zero in congestion.

[0137] Here, as Figure 2 As shown, in the first embodiment, during traffic congestion, low-speed driving is more frequent and background noise tends to decrease (S109: Yes), making it easy for engine 1 to stop (S107), and difficult to obtain the timing of engine 1's operation. Therefore, during traffic congestion, engine 1 is stopped (S107) when the vehicle speed is zero (stopped) (S109A: Yes), and engine 1 continues to operate during low-speed driving (S109A: No). As a result, engine 1 operates with fewer opportunities to generate background noise during low-speed driving in traffic congestion, thereby making it easier to maintain the catalyst temperature at or above the lower activity limit temperature.

[0138] In this embodiment, if the congestion situation and other conditions are further met, the upper limit value of noise control used in step S102 is changed.

[0139] Figure 8 This is a flowchart illustrating the control process for changing the upper limit of background noise control. Furthermore, the control for changing the upper limit of background noise control can be executed at any time, or at any other time. Figure 7 The preceding and following executions of engine motion control are shown.

[0140] In step S401, the motor controller 11 determines whether the conditions for changing the background noise control upper limit are met. If the conditions are met (S401: Yes), the motor controller 11 increases the background noise control upper limit in step S402. Conversely, if the conditions are not met (S401: No), the motor controller 11 terminates the background noise control upper limit change control.

[0141] As an example, consider the scenario where the path of vehicle 100 is congested, as a change condition. In congested conditions, engine 1 has fewer opportunities to operate, and the catalyst temperature is more likely to drop below the lower limit temperature. When the path of vehicle 100 is congested, increase the upper limit value for background noise control.

[0142] As another example, the external temperature of the vehicle 100 is considered as a change condition in step S401. Specifically, if the external temperature is below a specified threshold, the change condition is deemed met. The lower the external temperature, the easier it is for the catalyst temperature to drop below the lower limit temperature through natural cooling. Therefore, by increasing the upper limit of the background noise control value in advance and more aggressively causing the engine 1 to operate, the catalyst temperature is more likely to rise.

[0143] Furthermore, as another example, the vehicle speed of vehicle 100 is considered as a change condition. If the vehicle speed exceeds a specified threshold, the change condition is deemed met. The faster the vehicle speed, the easier it is for the catalyst temperature to drop below the lower limit temperature through natural cooling. Therefore, by pre-increasing the upper limit of the background noise control, the engine 1 is made to operate more aggressively, thus making it easier for the catalyst temperature to increase.

[0144] When congestion occurs, background noise is low, making it difficult for engine 1 to operate. Therefore, by pre-increasing the upper limit of the background noise control and actively activating engine 1, the catalyst temperature can easily increase. Furthermore, as described above, when the background noise is low and the vehicle is stationary at zero speed (S109A: Yes), engine 1 is stopped (S107); on the other hand, engine 1 is activated when traveling at low speed (S109A: No). As a result, by activating engine 1 with fewer opportunities to generate background noise during low-speed travel in congestion, the catalyst temperature can be increased.

[0145] In addition, Figure 8 The change control shown modifies the upper limit of the background noise limit, but is not limited to it. The stop threshold can be changed along with the upper limit of the background noise limit. Even if the stop threshold is increased, it is difficult to stop engine 1, therefore the action parameters are prone to increase.

[0146] In the fourth embodiment, the following effects can be obtained.

[0147] According to the control method of the hybrid vehicle 100 in the fourth embodiment, the lower the temperature of the outside air of the hybrid vehicle 100, the lower the stop threshold (which may be the upper limit of the background noise control). The lower the outside temperature, the easier it is for the catalyst temperature to drop below the lower limit temperature through natural cooling. Therefore, by increasing the upper limit of the background noise control in advance to more aggressively cause the engine 1 to operate, the catalyst temperature is more likely to rise, and the catalyst temperature can be maintained at or above the lower limit of the activity temperature.

[0148] According to the control method of the hybrid vehicle 100 in the fourth embodiment, when it is determined that the vehicle is traveling on a congested road, and the hybrid vehicle 100 is not stopped but its speed is greater than zero, the engine 1 is made to perform an operation.

[0149] In congested traffic, the focus is on low-speed driving, thus background noise tends to be low, reducing the opportunities for engine 1 to operate. Therefore, in congested traffic, when background noise is low, engine 1 is stopped (S107) when stopped (S109A: Yes), but continues to operate (S109A: No) while driving at low speeds. As a result, by utilizing the opportunity of background noise generated during low-speed driving in congested traffic, engine 1 can be operated to increase the catalyst temperature. Consequently, it is easier to maintain the catalyst temperature above or equal to the lower activity limit temperature.

[0150] (Fifth Embodiment)

[0151] In the fifth embodiment, the cooling water temperature of the engine 1, obtained by the second temperature sensor 25, will be described as an operating parameter. The cooling water temperature of the engine 1 increases with the longer the engine 1 operates. Furthermore, there is a suitable temperature range for the cooling water temperature; if it falls below the lower limit, it will affect the heating function of the interior. Therefore, the engine 1 is activated when the cooling water temperature is below the lower limit.

[0152] The engine operation control in this embodiment uses the same process as in embodiments 1 to 4, employing coolant temperature as the operation parameter. Therefore, even when the coolant temperature is greater than or equal to the lower limit of the heating demand temperature (forced operation threshold), and the background noise is high, the engine 1 is still operated. Thus, the coolant temperature can be maintained at or above the lower limit of the heating demand temperature when the driver is unlikely to notice the engine 1's operation. On the other hand, when the background noise is low, the driver is likely to notice the engine 1's operation; therefore, by suppressing the engine 1's operation, the comfort inside the vehicle can be improved.

[0153] In this embodiment, the same method as in the fourth embodiment can be implemented. Figure 8 The background noise control upper limit value is shown for change control.

[0154] The external temperature outside the hybrid vehicle 100 is used as the condition for changing the background noise control upper limit. Specifically, the change condition is determined to be met when the external temperature is below a specified threshold. The lower the external temperature, the easier it is for the coolant temperature to drop below the heating request lower limit temperature through natural cooling. Therefore, by significantly changing the background noise control upper limit in advance to more aggressively activate the engine 1, the catalyst temperature is more likely to increase.

[0155] As another example, the blower airflow of the cooling system of engine 1 is taken into consideration as a change condition. If the blower airflow exceeds a specified threshold, the change condition is deemed met. The higher the blower airflow, the more easily the coolant temperature drops below the lower limit. Therefore, by significantly changing the upper limit of the background noise control in advance to more aggressively induce engine 1 to operate, the coolant temperature is more likely to increase.

[0156] In the fifth embodiment, the following effects can be obtained.

[0157] According to the control method of the hybrid vehicle 100 in the fifth embodiment, the temperature of the coolant in the engine 1, acquired by the second temperature sensor 25, is used as an operating parameter. There is a lower limit temperature (forced operation threshold) for the cooling water temperature used to implement heating, and this threshold increases based on the operating time of the engine 1. Therefore, even when the coolant temperature exceeds the lower limit temperature, the engine 1 is operated even in situations with high background noise, ensuring cabin comfort and maintaining the coolant temperature at or above the lower limit temperature. On the other hand, in situations with low background noise, the driver is more likely to notice the engine 1's operating sound; therefore, by suppressing the engine 1's operation, cabin comfort can be improved.

[0158] According to the control method of the hybrid vehicle 100 in the fifth embodiment, the lower the temperature of the outside air, the higher the stop threshold (which may be the background noise control upper limit). The lower the outside temperature, the easier it is for the coolant temperature to fall below the stop threshold through natural cooling. Therefore, by significantly changing the background noise control upper limit in advance to more aggressively cause the engine 1 to operate, the coolant temperature is more likely to rise, and the coolant temperature can be maintained at a temperature greater than or equal to the heating request lower limit temperature.

[0159] (Sixth Embodiment)

[0160] In the sixth embodiment, the state of charge (SOC) of the battery 3 will be described as an operation parameter. The SOC has the property of increasing according to the operating time of the engine 1. Furthermore, if the SOC is lower than the lower limit of the operating range (forced operation threshold), the engine 1 will be activated.

[0161] The engine operation control in this embodiment uses the same process as in the engine operation control of embodiments 1 to 4, employing State of Charge (SOC) as the operation parameter. Therefore, even when the SOC is greater than or equal to the lower limit of the operating range, and the background noise level is high, the engine 1 is still operated, thus increasing the SOC to a level where the driver is less likely to notice the engine 1's operation noise. On the other hand, when the background noise level is low, the driver is more likely to notice the engine 1's operation noise, thus improving cabin comfort by suppressing the engine 1's operation.

[0162] In this embodiment, the same method as in the fourth embodiment can be implemented. Figure 8 The background noise control upper limit value is shown for change control.

[0163] The conditions for changing the upper limit of background noise control in this embodiment include, for example, vehicle speed, electrical component power consumption, and the frequency of driver acceleration. The larger these parameters are, the easier it is to reduce the State of Charge (SOC). Therefore, by significantly changing the upper limit of background noise control in advance and more aggressively causing the engine 1 to operate, the SOC is more likely to increase.

[0164] In the sixth embodiment, the following effects can be obtained.

[0165] According to the control method of the hybrid vehicle 100 in the sixth embodiment, the state of charge (SOC) of the battery 3 is used as an operating parameter. There is a lower limit to the SOC's usability range, and this SOC increases depending on the operating time of the engine 1. Therefore, even when the SOC exceeds the lower limit, in situations with high background noise, it is possible to ensure cabin comfort and increase the SOC by operating the engine 1. On the other hand, in situations with low background noise, the driver is more likely to notice the engine 1's operating sound; therefore, by suppressing the engine 1's operation, cabin comfort can be improved.

[0166] According to the control method of the hybrid vehicle 100 in the sixth embodiment, the faster the hybrid vehicle 100 travels, the lower the background noise control upper limit (which can be equal to the stop threshold). Therefore, the faster the vehicle travels and the greater the power consumption, the easier it is for the State of Charge (SOC) to fall below the lower limit of the operating range. Thus, by significantly altering the background noise control upper limit in advance and more aggressively engaging the engine 1, it is easier to maintain the SOC at or above the lower limit of the operating range. Similarly, the greater the power consumption of electrical components and the higher the frequency of driver acceleration, the easier it is for the SOC to decrease; therefore, the background noise control upper limit can be significantly altered in advance.

[0167] (Seventh Embodiment)

[0168] In the seventh embodiment, the negative pressure of the brake booster of the friction brake 8, obtained by the pressure sensor 26, can be used as the operation parameter. The negative pressure has the property of increasing according to the operating time of the engine 1. In addition, there is an appropriate range for the negative pressure; if it is below the lower limit (forced operation threshold), it is difficult to obtain the auxiliary function of the brake booster when the brake pedal is pressed. Therefore, if the negative pressure is below the lower limit, the engine 1 is made to operate to increase the negative pressure.

[0169] The engine operation control in this embodiment uses the same process as in the engine operation control of embodiments 1 to 4, employing the aforementioned negative pressure as the operation parameter. Therefore, even when the negative pressure is greater than or equal to the lower limit, and the background noise level is high, the engine 1 is still operated, thus increasing the negative pressure so that the driver is less likely to notice the engine 1's operation noise. On the other hand, when the background noise level is low, the driver is more likely to notice the engine 1's operation noise, thus improving cabin comfort by suppressing the engine 1's operation.

[0170] In addition, similar to the fourth embodiment, it can be implemented Figure 8 The background noise control upper limit value is shown for change control.

[0171] As a condition for changing the upper limit of background noise control, for example, the frequency of the driver's brake pedal application. The higher the application frequency, the easier it is for the negative pressure of the brake booster to decrease. Therefore, by significantly changing the upper limit of background noise control in advance to make the engine 1 operate more aggressively, the negative pressure is more likely to increase.

[0172] Furthermore, as a change condition, congestion is considered in the predicted path of the hybrid vehicle 100. In congested conditions, the driver's brake pedal depressing frequency tends to increase. Therefore, by significantly altering the background noise control upper limit in advance to more aggressively engage the engine 1, negative pressure is likely to increase.

[0173] In the seventh embodiment, the following effects can be obtained.

[0174] According to the control method of the hybrid vehicle 100 in the seventh embodiment, the negative pressure of the brake booster of the friction brake 8 is used as an operation parameter. There is a lower limit (forced operation threshold) for the negative pressure, which increases according to the operating time of the engine 1. Therefore, even when the negative pressure exceeds the lower limit, the engine 1 is operated even in situations with high background noise, thereby ensuring cabin comfort and increasing the negative pressure. On the other hand, when background noise is low, the driver is more likely to notice the operating sound of the engine 1; therefore, by suppressing the operation of the engine 1, cabin comfort can be improved.

[0175] According to the control method of the hybrid vehicle 100 in the seventh embodiment, the higher the operating frequency of the brake pedal, the lower the background noise control upper limit (which may be a stop threshold). The higher the operating frequency of the brake pedal, the easier it is to reduce the negative pressure. Therefore, by significantly changing the background noise control upper limit in advance and more aggressively causing the engine 1 to operate, it is possible to maintain the negative pressure at a level greater than or equal to the lower limit.

[0176] (Eighth Embodiment)

[0177] In embodiments 1 through 7, examples using one motion parameter were described, but the embodiments are not limited thereto. In this embodiment, examples using multiple motion parameters are described.

[0178] In this embodiment, engine operation control is performed using two operating parameters: the catalyst temperature obtained by the first temperature sensor 24 and the coolant temperature obtained by the second temperature sensor 25. Details of this engine operation control are shown in the table below.

[0179] [Table 4]

[0180]

[0181] In this table, the catalyst temperature conditions are shown in the column direction, and the cooling water temperature conditions are shown in the row direction. Furthermore, for readability, in this figure, for both cooling water temperature and catalyst temperature, the cases of being less than the stop threshold and greater than or equal to the background noise control upper limit, and the cases of being less than the background noise control upper limit and greater than or equal to the forced action threshold, are shown together as the case of being less than the stop threshold and greater than or equal to the forced action threshold.

[0182] As shown in row 1, engine 1 will not operate if the coolant temperature exceeds the stop threshold. Similarly, as shown in the left column, engine 1 will not operate if the catalyst temperature exceeds the stop threshold.

[0183] On the other hand, as shown in the central cell (2 rows, 2 columns), when the catalyst temperature is below the stop threshold but greater than or equal to the forced activation threshold, and when the coolant temperature is below the stop threshold but greater than or equal to the forced activation threshold, the presence or absence of engine 1 operation is determined based on the background noise level. The specific processing for determining the presence or absence of operation corresponding to this background noise level is as follows... Figure 2 The processing steps S103 to S109 are the same.

[0184] Furthermore, in states other than those described above (2 rows 3 columns, 3 rows 2 columns, 3 rows 3 columns), engine 1 is activated. Therefore, even when multiple parameters are used, the presence or absence of engine 1 activation can be controlled based on the background noise level. As a result, when the background noise level is high, engine 1 is activated, thus increasing the activation parameters when the driver is less likely to notice the engine 1's operation. On the other hand, when the background noise level is low, the driver is more likely to notice the engine 1's operation, thus improving cabin comfort by suppressing engine 1's operation.

[0185] According to the eighth embodiment, the following effects can be obtained.

[0186] According to the control method for a hybrid vehicle in the eighth embodiment, multiple operating parameters are employed. Even when multiple operating parameters are employed, engine 1 operation control is performed in accordance with the background noise even when both operating parameters are between a stop threshold and a forced operation threshold. Therefore, engine 1 can only operate when the background noise is high, thus increasing the operating parameters through engine 1 operation when the engine noise is difficult for the driver to notice. On the other hand, when the background noise is low, the driver easily notices the engine noise, thus improving cabin comfort by suppressing engine 1 operation.

[0187] The embodiments of the present invention have been described above, but these embodiments only illustrate a part of the application examples of the present invention, and their purpose is not to limit the technical scope of the present invention to the specific structures of the above embodiments. Furthermore, while each of the above embodiments has been described as a separate embodiment, they can also be appropriately combined.

Claims

1. A control method for a hybrid vehicle, the hybrid vehicle comprising: an electric motor as a drive source; a battery supplying power to the electric motor; and an engine capable of driving a generator to supply power to the battery, wherein... When the value of a parameter that increases with longer engine operating time is below a forced operating threshold, and when the value of the parameter causing the engine to perform an action is greater than the forced operating threshold, and when the background noise level exceeds a noise threshold, the engine is forced to perform an action. Furthermore, the larger the action parameter, the greater the noise threshold. If the action parameters exceed the stop threshold, the engine is stopped, and... The operating parameter is the SOC of the battery. The faster the hybrid vehicle travels, the higher the threshold for comparing the action parameters in the engine stop determination.

2. The control method for a hybrid vehicle according to claim 1, wherein, Furthermore, if the background noise level is lower than the noise threshold, the engine is stopped.

3. The control method for a hybrid vehicle according to claim 1, wherein, If it is determined that the hybrid vehicle is traveling on a congested road, and the background noise level is lower than the noise threshold and the speed of the hybrid vehicle is zero, the engine is stopped.

4. The control method for a hybrid vehicle according to any one of claims 1 to 3, wherein, Furthermore, if the background noise exceeds the noise threshold, the greater the background noise, the greater the engine output.

5. A hybrid vehicle comprising: an electric motor as a drive source; a battery supplying power to the electric motor; an engine capable of driving a generator to supply power to the battery; and a controller controlling the engine, wherein... When the value of a parameter that increases with longer engine operating time is below a forced operating threshold, and when the value of the parameter causing the engine to perform an action is greater than the forced operating threshold, and when the background noise level exceeds a noise threshold, the controller causes the engine to perform an action. Furthermore, the larger the action parameter, the greater the noise threshold. If the action parameters exceed the stop threshold, the engine is stopped, and... The operating parameter is the SOC of the battery. The faster the hybrid vehicle travels, the higher the threshold for comparing the action parameters in the engine stop determination.

Images