System and method for controlling operation of a motor vehicle

Abstract

Method for controlling operation of a motor vehicle, comprising: Setting; by a control unit (150), a creep torque as a minimum torque (S10); Setting, by the control unit (150), a maximum torque as a sum of a maximum torque of an internal combustion engine (160) and a maximum torque of a motor (170) (S20); Monitoring a pedal position sensor (APS) value (S30); Calculating, by the control unit (150), a requested torque based on the APS value (S40); Setting, by the control unit (150), a filter coefficient (10) for filtering the requested torque based on an operating state of the vehicle (S50); and Filtering the requested torque with the filter coefficient (10) (S60); wherein the operating state is selected from the group consisting of an traction control system (ASR), an electronic stability program (ESP), a state of charge (SOC), a rate of change of the APS value, a rate of change of the BPS value and a current drive mode; wherein, when a control flag for the ASR or the ESP is switched on, the filter coefficient (10) is set to a small value such that the requested torque is changed quickly; and wherein at low SOC the filter coefficient (10) is set to a large value such that the requested torque changes slowly, where each possible operating state is assigned a priority value and the priority values are set in an order of 1. the ASR or the ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is driving in an eco drive mode, 4. the vehicle is driving on a city road, and 5. the vehicle is driving on a motorway.

Description

BACKGROUND OF THE INVENTION(a) Field of the Invention

[0001] The present invention relates to a system and method for controlling the operation of a motor vehicle. More particularly, the present invention relates to a system and method for controlling the operation of a hybrid motor vehicle that changes a filter coefficient for determining a driver-requested torque according to the current operating state of the vehicle. (b) Description of the prior art

[0002] When designing logic to control the operation of a hybrid vehicle, the logic that calculates a requested torque for a driver should accurately reflect the driver's intention. The driver's intention with respect to hybrid vehicle operating parameters such as acceleration, deceleration, maintaining a speed, etc., should be implemented by the logic to drive the vehicle in the manner requested by the driver. If the logic calculates a requested torque that does not fully reflect the driver's intention, then the vehicle will be driven in a manner different from the driver's intention. As a result, drivability may deteriorate, while increasing the risk of an accident.Given the above, it is clear that it is important to ensure that the logic accurately calculates the requested torque for the driver's request.

[0003] In general, the driver's request can be understood based on data values acquired by an acceleration pedal position sensor (APS) and a brake pedal position sensor (BPS). An acceleration torque can be calculated by multiplying the sum of a minimum torque and a maximum torque by the value acquired by the APS. As described in Fig. As shown in Figure 1, if the minimum torque is -60 Nm, the maximum torque is 200 Nm, and the value detected by the APS is 50%, the acceleration torque is 70Mn ((-60 + 200) * 0.5). Furthermore, a deceleration torque can be calculated based on the value detected by the BPS. That is, the amount of regenerative braking and the amount of hydraulic braking can be determined based on the value detected by the BPS, and the deceleration torque is calculated from a predetermined function according to the amount of regenerative braking and the amount of hydraulic braking.

[0004] If the driver wants to accelerate, the acceleration torque can be increased proportionally to the value detected by the APS. Conversely, if the driver wants to decelerate, the value detected by the BPS increases. The requested torque that meets the driver's request and is suitable for the current vehicle operation can be calculated by considering the current gear ratio and vehicle speed in addition to the values detected by the APS and BPS. When calculating the requested torque for the driver's request, the requested torque should be filtered so that it does not change too rapidly, and the filtered requested torque should be controlled so that it does not deviate from the driver's request.In addition, the requested torque should not be calculated by excessively filtering the requested torque, as otherwise it may differ from the driver's request.

[0005] According to the conventional method for calculating a requested torque, the creep torque that allows the vehicle to travel in a creeping gear when the value detected by the APS is 0% can be set as the minimum torque, and the sum of the maximum engine torque and the maximum motor torque can be set as the maximum torque. In other words, the minimum torque represents the torque when the APS value is 0%, and the maximum torque represents the torque when the APS value is 100%. The requested acceleration torque is calculated according to the vehicle speed and the APS value, and the calculated requested acceleration torque is filtered by a constant filter coefficient so that it does not change too rapidly. Unfortunately, the conventional technique filters the demand torque with a constant filter coefficient, as shown in Fig. 1, which means that the current operating state is not fully reflected by the resulting filtered demand torque. For example, when a signal is input from a traction control system (TCS) or an electronic stability program (ESP), the demand torque should directly reflect the driver's safety intention quickly. However, because the conventional technology implements a filter coefficient with a fixed value, the current operating state is not accurately and quickly reflected in the demand torque response, and the driver cannot operate the vehicle safely.

[0006] In this context, DE 10 2004 044 507 A1 discloses a method for operating a vehicle drive system, comprising at least one internal combustion engine and at least one electric motor mechanically coupled to the at least one internal combustion engine, as well as an energy storage device operatively connected to the electric motor and / or the internal combustion engine. The at least one internal combustion engine and the at least one electric motor generate a requested drive target torque at least approximately together, wherein a requested optimal target torque of the internal combustion engine is limited to an optimized minimum torque above a minimum internal combustion engine torque or an optimized maximum torque below a maximum internal combustion engine torque, and / or a rate of change of the optimal target torque of the internal combustion engine is limited.

[0007] DE 10 2006 016 133 A1 also discloses a method for operating a drive device of a vehicle, which has at least one internal combustion engine and at least one electric machine as drive units, the torques of which are used to generate a drive torque of the vehicle depending on different operating modes, and with at least one signal flow controlling at least one drive unit in at least one operating mode, wherein a single signal flow controls at least one of the drive units in all operating modes by specifying at least one torque limit.

[0008] Finally, DE 10 2009 054 945 A1 describes a method for operating a drive device with at least one drive machine generating the torque output by the drive device, wherein a first parameter causing a slow change in the torque output by the drive device and a second parameter causing a rapid change in the torque are used to set a target torque. OVERVIEW OF THE INVENTION

[0009] It is therefore an object of the present invention to provide a system and a method for controlling an operation of a hybrid motor vehicle, which takes into account the current operating conditions of the vehicle and calculates a requested torque so as to prevent an acceleration torque from being exerted.

[0010] The object is achieved by a method having the features of claim 1 and a system having the features of claim 5. Advantageous further developments can be found in the subclaims.

[0011] A method for controlling operation of a hybrid motor vehicle according to an embodiment of the present invention may include: setting a creep torque as a minimum torque; setting a maximum torque as the sum of the maximum torque of the internal combustion engine and the maximum torque of the motor; monitoring an accelerator pedal position sensor (APS) value; calculating a requested torque according to the APS value; setting a filter coefficient for filtering the requested torque according to operating conditions of the vehicle; and filtering the requested torque by the filter coefficient, wherein the operating condition is selected from the group consisting of traction control (ASR), electronic stability control (ESP), state of charge (SOC), a change rate of the APS value, a change rate of the BPS value, and a current drive mode;wherein, when a control flag for the ASR or the ESP is switched on, the filter coefficient is set to a small value such that the requested torque is changed quickly; and wherein, when the SOC is low, the filter coefficient is set to a large value such that the requested torque changes slowly, wherein each possible operating state is assigned a priority value and the priority values are set in an order of 1. the ASR or the ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is running in an eco-drive mode, 4. the vehicle is running on a city road, and 5. the vehicle is running on a highway.;

[0012] In an illustrative manner, priorities can be related to certain operating states and the filter coefficient can be adjusted according to the operating states with the higher priority.

[0013] A system for controlling driving of a motor vehicle according to another embodiment of the present invention may be applied to the vehicle including an internal combustion engine and a motor. The system may further include a control section adapted to control the internal combustion engine and the motor. The control section may be adapted to calculate a requested torque according to an APS value and to filter the requested torque by a filter coefficient according to the operating conditions of the vehicle. The operating conditions may include at least one of an anti-skid control (ASR), an electronic stability program (ESP), a state of charge (SOC), a rate of change of the APS value, and a current drive mode.When a control flag for the ASR or ESP is enabled, the filter coefficient is set to a small value so that the requested torque changes quickly, and when the SOC is low, the filter coefficient is set to a large value so that the requested torque changes slowly. Each possible operating state is assigned a priority value, and the priority values are set in the order of 1. the ASR or ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is driving in eco-drive mode, 4. the vehicle is driving on a city road, and 5. the vehicle is driving on a highway. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a schematic diagram for explaining a concept of a method for controlling driving of a motor vehicle according to the prior art. Fig. 2 shows a block diagram of a system for controlling driving of a motor vehicle according to an embodiment of the present invention. Fig. 3 shows a flowchart of a method for controlling an operation of a motor vehicle according to an embodiment of the present invention. Fig. 4 shows a schematic diagram illustrating a method for controlling an operation of a motor vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] Reference will now be made in detail to the various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the invention will be described in connection with the embodiment, it is to be understood that the present description is not intended to limit the invention to the embodiment. On the contrary, the invention is intended to cover not only the embodiments, but also various alternatives, modifications, equivalents, and other embodiments which may be included within the spirit and scope of the invention as defined by the appended claims.

[0015] It is understood that the term "vehicle" or "vehicle-," or other synonymous terms as used herein, includes all hybrid motor vehicles in general, such as passenger cars, including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft, including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuel derived from sources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more power sources, such as both gasoline-powered and electric-powered vehicles.

[0016] Fig. 2 shows a block diagram of a system for controlling operation of a motor vehicle according to an embodiment of the present invention. As in Fig. 2, a system for controlling operation of a motor vehicle according to an embodiment of the present invention includes, but is not limited to, an APS 110, an ASR 120, an ESP 130, an SOC detector 140, a control unit 150, an internal combustion engine 160, and a motor 170.

[0017] The APS 110 detects the position of an accelerator pedal (e.g., the degree of depression of an accelerator pedal) and provides a corresponding signal to the control unit 150. If the accelerator pedal is fully depressed, the accelerator pedal position is 100%, and if the accelerator pedal is not depressed at all, the accelerator pedal position is 0%. A throttle valve opening sensor mounted on an intake passage may be used instead of or in conjunction with the APS 110. Therefore, it is understood that the APS 110 may include the throttle valve opening sensor.

[0018] The ASR 120 controls the vehicle's drive torque. If the ASR 120 needs to be regulated, it sends a corresponding signal to the control unit 150.

[0019] The ESP 130 analyzes the steering wheel position and promotes vehicle stability by applying brake pressure to the wheel, reducing engine torque, or performing gear shifts based on the steering wheel position. If the ESP 130 requires control, the ESP 130 sends a corresponding signal to the control unit 150.

[0020] The SOC detection device 140 detects the SOC of the battery and provides a signal corresponding thereto to the control section 150. Instead of directly detecting the SOC of the battery, the current and voltage of the battery may also be detected and the SOC of the battery may be calculated based thereon.

[0021] The control section 150 calculates an acceleration torque based on the signals received from the APS 110, the ASR 120, the ESP 130, and the SOC detector 140 and filters the calculated acceleration torque using a filter coefficient. Furthermore, the control unit 150 calculates the engine torque and the motor torque based on the filtered acceleration torque and controls the engine 160 and the motor 170 based on the engine torque and the motor torque. In other words, the control unit 150 may include one or more processors activated by a predetermined program, and the predetermined program may be programmed to perform each step of a method for controlling an operation of a motor vehicle according to an embodiment of this invention.

[0022] Although the above embodiment is described as using a plurality of units to perform the above process, it should be understood that the above processes may also be performed by a single controller or unit.

[0023] Furthermore, the control logic (of the control portion) of the present invention may be embodied as non-transitory computer-readable media on a computer-readable medium comprising executable program instructions executed by a processor, controller, or the like. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, compact disk (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium may also be decentralized in network-coupled computer systems so that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0024] Fig. 3 shows a flowchart of a method for controlling an operation of a motor vehicle according to an embodiment of the present invention. As in Fig. 3, the method for controlling an operation of a motor vehicle according to an embodiment of the present invention comprises setting a creep torque as a minimum torque in a step S10, setting the maximum torque as a sum of the maximum torque of the internal combustion engine and the maximum torque of the motor in a step S20, monitoring the accelerator pedal position sensor (APS) value in a step S30, calculating a requested torque according to the APS value in a step S40, setting a filter coefficient (e.g., see Fig. 4, Fig. 10) for filtering the requested torque according to the operating conditions of the vehicle in a step S50 and filtering the requested torque by the filter coefficient (e.g. see Fig. 4, Fig. 10) in a step S60.

[0025] First, the creep torque is set as the minimum torque in step S10. Creep torque refers to the torque that allows a vehicle to creep when the accelerator pedal is not depressed. In other words, vehicle creep refers to the condition where a driver does not depress the accelerator pedal and the vehicle creeps forward using the engine's idle speed or the motor's electric torque. Vehicle creep is mainly performed when the road is congested or the driver wants to move forward slowly.

[0026] The system for controlling operation of a motor vehicle determines the driver's intention by receiving the signal from the APS and / or a brake switch. In particular, the system for controlling operation of a motor vehicle used in a hybrid vehicle determines a final output torque based on an output torque of the engine 160 and an output torque of the motor 170 according to the SOC of the battery to achieve the demand torque according to the driver's request. The output torque of the engine 160 is determined by an engine control unit (not shown), and the output torque of the motor 170 is determined by an engine control unit (not shown). The engine control unit and the engine control unit can be controlled by the control unit 150 or integrated with the control unit 150.

[0027] When the hybrid vehicle is traveling slowly or stopped and the driver has no intention of accelerating (i.e., the driver is not pressing the accelerator pedal), the use of engine power is minimized to generate creep torque and reduce fuel consumption. Accordingly, engine 160 is stopped, and creep torque is generated using the electric power of motor 170 while creeping. Creep torque is generated by the motor according to the battery SOC, and the battery SOC may be reduced if creeping takes too long. In this case, engine 160 may be restarted, and the battery is charged by engine 160.

[0028] Meanwhile, when the vehicle is traveling slowly or stopped and the driver has no intention to accelerate (ie, the driver is not pressing the accelerator pedal), the engine 160 may generate creep torque according to a conventional vehicle engine (e.g., an internal combustion engine). At this time, the engine 160 generates creep torque to minimize power consumption.

[0029] As a result of setting the creep torque as the minimum system torque, the vehicle can creep even though the APS value is 0%. Subsequently, the sum of the maximum torque of the internal combustion engine 160 and the maximum torque of the motor 170 is set as the maximum system torque in step S20.

[0030] As described above, the final torque can be determined based on the output torque of the engine 160 and the output torque of the motor 170 according to the SOC of the battery in the case of the hybrid vehicle. Accordingly, the maximum value of the final output torque is set as the maximum torque of the system.

[0031] In the state where the minimum torque and maximum torque are set, the APS value is monitored in step S30. In other words, the amount of acceleration the driver presses the accelerator pedal is continuously monitored by the APS.

[0032] The driver's demand torque may be calculated according to the monitored APS value in step S40. Specifically, the demand torque may be the minimum torque (creep torque) if the APS value is 0%, and the demand torque may be the maximum torque if the APS value is 100%. Accordingly, the driver's demand torque may be calculated according to the APS value.

[0033] If the driver presses the accelerator pedal and the APS value is 50%, the requested torque can be switched between a maximum torque characteristic curve connecting the maximum torques and a minimum torque characteristic curve connecting the minimum torques as in Fig. 3. For example, the requested torque may be calculated to be 70 Nm. The filter coefficient 10 for filtering the requested torque may be set according to the operating conditions in step S50. Furthermore, the requested torque may be filtered using the filter coefficient 10 in step S60, and driving of the vehicle is controlled. The filter coefficient (e.g., see Fig. 4, Fig. 10) filters the driver's requested torque so that it is not changed too quickly.

[0034] As in Fig. 1, since the filter coefficient in the prior art is a constant value, it is difficult to cope with different operating conditions.

[0035] As in Fig. 3, the filter coefficient 10 (see Fig.4) However, in one embodiment of the present invention, it is changed and adjusted according to the operating state of the vehicle. Since the filter coefficient 10 is adjusted by reflecting the various operating states of the vehicle, it is improved to cope with a current operating state.

[0036] The operating states include at least one of the ASR, the ESP, the SOC, a rate of change of the APS value and a current drive mode.

[0037] In the case where a control flag for the ASR or ESP is activated (i.e., control of the ASR or ESP is required), the filter coefficient 10 can be set to a small value so that the driver's requested torque is changed quickly in one or more embodiments. If the control flag for the ASR or ESP control is activated, the vehicle operating conditions may reflect an emergency situation or indicate that the vehicle is approaching a hazardous situation. Accordingly, the driver's request should be honored.

[0038] In the case where the SOC of the battery is low, the filter coefficient may be set to a large value so that the requested torque changes slowly in one or more embodiments.

[0039] In one or more embodiments, the filter coefficient may be changed according to the rate of change of the APS value and the drive mode. As stated above, the state of the ASR, ESP, SOC, the rate of change of the APS value, and the current drive mode represent non-limiting examples of vehicle operating states. Accordingly, the filter coefficient may also be adjusted according to various vehicle operating states that differ from the operating states described above.

[0040] Priorities for setting the filter coefficient can be set to various operating conditions, including whether the ASR is operating, whether the ESP is operating, the SOC, the rate of change of the APS value, and the current drive mode, and the filter coefficient can be changed and set according to the occurrence of the operating conditions associated with a higher priority.

[0041] In one or more embodiments, the operating state priorities may, for example, be set in an order of 1. the ASR or ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is driving in an eco drive mode, 4. the vehicle is driving on a city street, and 5. the vehicle is driving on a highway.

[0042] For example, if the vehicle is traveling on a highway, the filter coefficient 10 can be set accordingly, and the requested torque can be filtered by the filter coefficient 10 to correspond to highway driving. Consider, for example, the situation where the vehicle's ASR or ESP is operating due to the presence of obstacles on the road. In this case, since the operation of the ASR or ESP has higher priority than highway driving, the requested torque can be filtered by applying the filter coefficient 10 according to the operation of the ASR or ESP. Consequently, the driver's request can be immediately transferred to the vehicle's operation, and the vehicle can avoid the emergency situation.

[0043] The control unit 150 divides the filtered demand torque of the engine 160 and the motor 170. If the maximum torque that can be output by the engine 160 is Tm,eng and the maximum torque that can be output by the motor 170 is Tm,mot, the torque Teng divided between the engine 160 and the torque Tmot divided between the motor 170 are calculated using the following equations. Teng=T*Tm,eng / (Tm,eng+TM,mot) Tmot=T*Tm,mot / (Tm,eng+Tm,mot)

[0044] Here, T denotes the requested torque of the vehicle.

[0045] If the torques divided between the engine 160 and the motor 170 are calculated, the control unit 150 controls the engine 160 and the motor 170 based thereon.

[0046] Actual testing of the system and method according to an embodiment of the present invention on the hybrid vehicle showed that safety and fuel consumption were improved by adjusting the filter coefficient according to different operating conditions and changing the driver's requested torque. Since the filter coefficient can be changed according to the current operating condition of the vehicle according to an embodiment of the present invention, the vehicle's operating condition is fully reflected in the requested torque, and thus safety can be improved. Since a rapid change in acceleration torque is prevented by changing the filter coefficient according to the current operating condition of the vehicle, fuel economy can also be improved.

Claims

[1] A method for controlling an operation of a motor vehicle, comprising: Setting; by a control unit (150), a creep torque as a minimum torque (S10); Setting, by the control unit (150), a maximum torque as a sum of a maximum torque of an internal combustion engine (160) and a maximum torque of a motor (170) (S20); Monitoring a pedal position sensor (APS) value (S30); Calculating, by the control unit (150), a requested torque based on the APS value (S40); Setting, by the control unit (150), a filter coefficient (10) for filtering the requested torque based on an operating state of the vehicle (S50); and Filtering the requested torque with the filter coefficient (10) (S60); wherein the operating state is selected from the group consisting of an traction control system (ASR), an electronic stability program (ESP), a state of charge (SOC), a rate of change of the APS value, a rate of change of the BPS value and a current drive mode; wherein, when a control flag for the ASR or the ESP is switched on, the filter coefficient (10) is set to a small value such that the requested torque is changed quickly; and wherein at low SOC the filter coefficient (10) is set to a large value such that the requested torque changes slowly, where each possible operating state is assigned a priority value and the priority values are set in an order of 1. the ASR or the ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is driving in an eco drive mode, 4. the vehicle is driving on a city road, and 5. the vehicle is driving on a motorway. [2] The method of claim 1, wherein the pedal position sensor is an accelerator pedal position sensor (APS). [3] The method of claim 1, wherein the pedal position sensor is a brake pedal position sensor (BPS). [4] The method of claim 1, wherein the filter coefficient (10) is set to correspond to the operating states with high priority values. [5] A system for controlling operation of a hybrid motor vehicle, comprising: an internal combustion engine (160); an engine (170); one or more operating state sensors (110, 120, 130, 140) configured to generate sensor values; and a control unit (150); wherein the control unit (150) is adapted to control an internal combustion engine (160) and a motor (170) and to select a requested torque based on one or more of the sensor values, wherein the one or more operating state sensors (110, 120, 130, 140) are selected from the group consisting of a traction control system (ASR), an electronic stability program (ESP), a state of charge (SOC), a rate of change of the APS value, a rate of change of the BPS value, and a current drive mode, wherein, when a control flag for the ASR or the ESP is switched on, the filter coefficient (10) is set to a small value such that the requested torque is changed quickly; and wherein at low SOC the filter coefficient (10) is set to a large value such that the requested torque changes slowly, where each possible operating state is assigned a priority value and the priority values are set in an order of 1. the ASR or the ESP is operating, 2. a battery SOC discharge limit is present, 3. the vehicle is driving in an eco drive mode, 4. the vehicle is driving on a city road, and 5. the vehicle is driving on a motorway. [6] The system of claim 5, wherein the control unit (150) is further configured to assign a priority value to each operating state sensor value. [7] The system of claim 6, wherein the filter coefficient (10) corresponds to the operating state sensor value with the higher priority value.

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