Vehicle control device

Abstract

This vehicle control device: switches engine drive torque from a first torque to a second torque in response to a required engine torque exceeding a first threshold value, the first threshold value being set so as to fall within a range between a first value corresponding to a torque at which the engine achieves the highest fuel efficiency and a second value corresponding to a torque at which better fuel efficiency is achieved by increasing the output of an electric motor rather than by increasing the output of the engine; and performs assistance by increasing motor assist torque, in terms of a difference in engine drive torque between before and after the switching of the engine drive torque, during a period required for the engine drive torque to be switched from the first torque to the second torque.

Description

Vehicle control device

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

[0002] Hybrid vehicles equipped with an engine and a rotating electric machine (motor, generator, motor generator) have become popular. Hybrid vehicles have multiple driving modes. The driving modes include an electric vehicle (EV) mode in which the vehicle runs solely on the motor using battery charging power, a series mode in which the vehicle runs solely on the motor while the engine generates electricity for the generator, and a parallel mode in which the vehicle runs primarily on the engine while providing assistance from the motor when necessary.

[0003] Furthermore, when using two power sources, an engine and a motor, there is a demand for efficient use of fuel by switching between modes, etc. For example, Patent Document 1 discloses a configuration that achieves both stabilization of vehicle acceleration performance and reduction of fuel consumption by efficiently using the engine and the motor.

[0004] Japanese Patent Application Publication No. 2003-146115

[0005] In parallel mode, where the engine and motor can be used simultaneously as drive sources, it is necessary to consider the balance between the driving force provided by the engine as a power source and the driving force provided by the motor as an assist in order to improve fuel consumption (fuel economy). Furthermore, the engine may output torque more efficiently, resulting in a torque that exceeds the required torque. By using this surplus as power for generating electricity, it is possible to reduce unnecessary energy consumption. Therefore, there is a demand for more fuel-efficient driving control that takes into account the timing of switching between driving based on engine driving force and power generation, and the timing of assist using motor driving force.

[0006] On the other hand, when switching between engine output and motor output to optimize fuel economy, the response to driver requests, such as acceleration, may be reduced. This phenomenon may occur, for example, in a region where changes in driver requests are realized by changes in engine torque.

[0007] The present invention was devised in view of the above-mentioned problems, and aims to improve responsiveness to driver requests while performing fuel-efficient driving control during parallel mode driving. However, this is not the only objective of the present invention. Another objective of the present invention is to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the following detailed description of the preferred embodiments of the present invention.

[0008] A vehicle control device according to one embodiment of the present invention has the following configuration: A control device for a vehicle capable of running in a parallel mode using engine drive torque from an engine and motor assist torque from a motor, comprising: a control unit that causes the vehicle to run by gradually switching the engine drive torque in accordance with a required drive torque, the control unit switching the engine drive torque from a first torque to a second torque in accordance with the required drive torque exceeding a first threshold value, the first threshold value being set between a first value corresponding to a torque at which the engine has the best fuel economy and a second value corresponding to a torque at which increasing the output from the motor is more fuel efficient than increasing the output from the engine, and the control unit assists by increasing the motor assist torque to make up for a difference between before and after the switching of the engine drive torque during a period required for switching the engine drive torque from the first torque to the second torque.

[0009] According to the present invention, in a parallel mode in which the engine and the motor can be used as drive sources, it is possible to perform fuel-efficient driving control while improving responsiveness to driver requests.

[0010] 1 is a schematic diagram showing an example of the configuration of a vehicle according to an embodiment of the present invention; FIG. 2 is a graph illustrating torque in driving control in a conventional parallel mode; FIG. 3 is a graph illustrating driving control in a conventional parallel mode; FIG. 4 is a graph illustrating torque in driving control in a parallel mode according to a first embodiment; FIG. 5 is a graph illustrating driving control in a parallel mode according to the first embodiment; FIG. 6 is a schematic diagram illustrating a flow of torque control according to the first embodiment;

[0011] A vehicle control device according to an embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described in the following embodiments. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed. In addition, the same reference numerals are used to indicate corresponding relationships between the same components in the drawings.

[0012] First Embodiment [Overall Configuration] A vehicle 100 to which a control device according to this embodiment can be applied will be described. The vehicle 100 is a hybrid vehicle including an engine 101 as a drive source, a motor 107 (rotating electric machine) for driving, and a generator 102 for generating electricity. Therefore, the vehicle 100 according to this embodiment can be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV: a plug-in hybrid capable of external charging or external power supply). In this embodiment, the vehicle 100 will be described as a front-wheel drive vehicle, but the present invention is not limited thereto, and rear-wheel drive, four-wheel drive, or the like may also be used.

[0013] The generator 102 is connected to the engine 101 and can operate independently of the operation of the motor 107. The engine 101 is connected to a drive shaft 104 via an engine clutch 103. When the engine clutch 103 is engaged, power generated by the engine 101 is transmitted to the drive shaft 104. The motor 107 is connected to the drive shaft 104 via a motor clutch 106. When the motor clutch 106 is engaged, power generated by the motor 107 is transmitted to the drive shaft 104. For convenience, the power transmission path via the engine clutch 103 is also referred to as a "first power transmission path," and the power transmission path via the motor clutch 106 is also referred to as a "second power transmission path."

[0014] Driving wheels 105 (front wheels) are mounted on the driving shaft 104. Driven wheels 116 (rear wheels) are mounted on the axle 115.

[0015] The vehicle 100 is also provided with an ECU (Electronic Control Unit) 108, which corresponds to the control device according to this embodiment. The ECU 108 is an electronic control device configured as, for example, an LSI (Large-Scale Integration) device or an embedded electronic device that integrates a microprocessor, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ECU 108 acquires signals detected by various sensors provided in the vehicle 100 and controls the vehicle 100. The sensors provided in the vehicle 100 include an accelerator position sensor 109, a brake sensor 110, a speed sensor 111, an engine rotation sensor 112, and a battery remaining capacity sensor 113. The accelerator position sensor 109 detects the amount of depression (accelerator position) of an accelerator pedal (not shown). The brake sensor 110 detects the amount of depression of a brake pedal (not shown). The speed sensor 111 detects the vehicle speed of the vehicle 100. The engine rotation sensor 112 detects the rotation speed of the engine 101. The battery remaining amount sensor 113 detects the remaining amount (SOC: State Of Charge) of the battery 114. The vehicle 100 is provided with a drive battery 114, which supplies and charges electric power.

[0016] The engine 101 is an internal combustion engine (gasoline engine or diesel engine) that uses gasoline or diesel as fuel. The operating state of the engine 101 may be controlled by the ECU 108, or may be controlled by an electronic control device (not shown) separate from the ECU 108. The generator 102 and the motor 107 according to this embodiment are motor-generators that function as both an electric motor and a generator. The motor 107 is a drive source that exchanges electric power with the battery 114, functions mainly as an electric motor to drive the vehicle 100, and functions as a generator during regeneration.

[0017] The generator 102 functions as an electric motor (starter) when starting the engine 101, and is driven by engine power to generate electricity when the engine 101 is running. Furthermore, the generator 102 transmits driving force to a drive shaft 104 of the vehicle 100 in a powered state. An inverter (not shown) that converts direct current and alternating current is provided around (or inside) each of the motor 107 and the generator 102. The rotation speeds and operating states (powered operation, regenerative / powered operation) of the motor 107 and the generator 102 are controlled by controlling the inverter (not shown).

[0018] The vehicle 100 can run in a plurality of driving modes, such as EV mode, series mode, parallel mode, etc. These driving modes are selected by the ECU 108 in accordance with the vehicle state, driving state, the driving force required by the driver, etc. Furthermore, the operations of the engine 101, generator 102, and motor 107 are selectively controlled depending on the driving mode.

[0019] The EV mode is a driving mode in which the vehicle 100 is driven solely by the motor 107 using the charging power of the drive battery 114 while the engine 101 and the generator 102 are stopped. The EV mode is selected, for example, when the required driving force and vehicle speed are both low or when the charge level of the battery 114 is high. The series mode is a driving mode in which the engine 101 drives the generator 102 to generate electricity and uses the generated electricity to drive the vehicle 100 by the motor 107. The series mode is selected, for example, when the required driving force is high or the charge level of the battery 114 is low. The parallel mode is a driving mode in which the vehicle 100 is driven primarily by the driving force of the engine 101 and, as needed, the motor 107 assists in driving the vehicle 100. The parallel mode is selected, for example, when the vehicle speed is high or the required driving force is high. In this embodiment, in the parallel mode, part of the driving force of the engine 101 (excess torque) can also be used as power for generating electricity for the battery 114.

[0020] An engine 101 and a motor 107 are connected in parallel to drive wheels 105 (front wheels in this case) via a transaxle (not shown) incorporating multiple gears and clutches. The engine 101 is also connected to a generator 102 via a transaxle (not shown), and the power of the engine 101 is also transmitted to the generator 102.

[0021] A transaxle is a power transmission device that integrates a final drive (final reduction gear) including a differential and a transmission (reduction gear), and contains multiple mechanisms that transmit power between the driving source and the driven device.

[0022] The engine clutch 103 is, for example, a wet multi-plate clutch or a dog clutch. Power on the upstream side of the power transmission path (the engine 101 and generator 102 side) of the engine clutch 103 is transmitted to the drive shaft 104 when the engine clutch 103 is engaged (connected), and is cut off when the engine clutch 103 is disengaged (released). The engagement and disengagement states of the engine clutch 103 are controlled by the ECU 108.

[0023] The motor clutch 106 is, for example, a wet multi-plate clutch or a dog clutch. Power on the upstream side of the power transmission path from the motor clutch 106 (i.e., the driving force of the motor 107) is transmitted to the drive shaft 104 when the motor clutch 106 is engaged, and is cut off when the motor clutch 106 is disengaged. The engagement and disengagement states of the motor clutch 106 are controlled by the ECU 108.

[0024] For example, when the driving mode is EV mode or series mode, the engine clutch 103 is disengaged and the motor clutch 106 is engaged. When the driving mode is parallel mode and motor assist (driving force of the motor 107) is not required, the engine clutch 103 is engaged and the motor clutch 106 is disengaged. When the driving mode is parallel mode and motor assist is required, both the engine clutch 103 and the motor clutch 106 are engaged.

[0025] [Driving Control] First, the problems with conventional driving control in parallel mode will be described with reference to the drawings. Fig. 2 is a graph illustrating torque transitions during driving control in conventional parallel mode. Fig. 3 is a graph illustrating driving control according to accelerator operation amount, corresponding to Fig. 2.

[0026] 2 shows the torque output state, with the vertical axis representing torque value and the horizontal axis representing time. From the top, Fig. 2 shows the driving torque of the vehicle 100, the torque due to the engine 101, the torque due to the generator 102, and the torque due to the motor 107. The sum of the torques shown in the bottom three graphs is the driving torque shown in graph 202.

[0027] Graph 201 shows the drive torque required for driving (hereinafter referred to as "required drive torque"). Here, this will be explained as being synonymous with the torque required by the driver's accelerator operation. On the other hand, graph 202 shows the drive torque resulting from the response by vehicle 100 (hereinafter referred to as "response drive torque"). Graph 203 shows the torque caused by engine 101. Graph 204 shows the torque caused by generator 102. Graph 205 shows the torque caused by motor 107. For generator 102, the range below 0 corresponds to power generation operation.

[0028] FIG. 3 is a graph illustrating conventional driving control in parallel mode. In FIG. 3, the vertical axis represents driving torque, and the horizontal axis represents accelerator operation amount. As described above, parallel mode is a mode in which driving is performed primarily using driving force from engine 101. A solid line 301 represents the required driving torque. A dashed line 302 represents the driving torque due to engine output. Note that, for simplicity of explanation, an example is shown in which the required driving torque changes at the same rate in response to the accelerator operation amount, but this change is not necessarily limited to this.

[0029] When the engine 101 is operated, it is controlled to have a predetermined torque in order to operate it in a state with the best possible fuel economy. Here, the torque obtained by operating the engine 101 in a state with the best fuel economy is referred to as "engine fuel economy torque" and indicated by T1. In addition, in the parallel mode, the torque at which assistance by the motor output starts in addition to the torque of the engine output is referred to as "assist start torque" and indicated by T2. In addition, the maximum torque that the engine 101 can output is referred to as "engine maximum torque." In FIG. 3, the relationship between the torques is T1<T2<T3.

[0030] The assist start torque T2 indicates the boundary at which fuel economy becomes better when torque is output by the motor 107 than when torque is output by the engine 101. In other words, when the assist start torque T2 is exceeded, it is assumed that, in order to further improve fuel economy, torque output by the motor 107 will provide better fuel economy than increasing the torque output by the engine 101.

[0031] In Fig. 3, area 303 indicates the torque for driving (hereinafter referred to as "engine drive torque") out of the torque due to the engine output. Area 304 indicates the torque for generating electricity by the generator 102 (hereinafter referred to as "engine power generation torque") out of the torque due to the engine output. Area 305 indicates the assist torque due to the motor output (hereinafter referred to as "motor assist torque").

[0032] First, when the accelerator operation amount is in the range from 0 to threshold A (shown as range a), by operating the engine 101 in a fuel-efficient state (i.e., constant at engine fuel efficiency torque T1), the required drive torque becomes lower than the engine fuel efficiency torque. Therefore, the difference ((engine fuel efficiency torque) - (required drive torque)) is diverted to power for generating electricity in the generator 102 (corresponding to region 304). In other words, when the accelerator operation amount is between 0 and threshold A, the torque from the engine output (i.e., engine fuel efficiency torque T1) is used to drive the vehicle 100 and charge the battery 114 using power generated by the generator 102. Threshold A is the accelerator operation amount corresponding to the position where the engine fuel efficiency torque T1 and the required drive torque match.

[0033] When the accelerator operation amount is in the range from threshold A to threshold B (shown as range b), the required drive torque exceeds the engine fuel consumption torque T1, so the torque from the engine output is increased in response to an increase in the accelerator operation amount. At this time, charging of the battery 114 (i.e., power generation by the generator 102 using the engine drive torque) is stopped. Threshold B is the accelerator operation amount corresponding to the position where the assist start torque T2 and the required drive torque match.

[0034] When the accelerator operation amount is in the range from thresholds B to C (shown as range c), the engine drive torque is controlled to be constant at assist start torque T2, and the motor assist torque increases as the accelerator operation amount increases. Therefore, the required drive torque is provided by the sum of the engine drive torque (i.e., constant at assist start torque T2) and the motor assist torque. The motor assist torque can be output by driving the motor 107 using the power stored in the battery 114 in range a. Threshold C is the accelerator operation amount corresponding to the position where the motor assist torque becomes maximum (hereinafter referred to as "motor assist maximum torque").

[0035] If the accelerator operation amount further increases and exceeds threshold C (shown as range d), the motor assist torque reaches the motor assist maximum torque and cannot be increased any further. Therefore, while maintaining the motor assist torque at the motor assist maximum torque, the engine drive torque is increased in response to an increase in the accelerator operation amount. At this time, the engine drive torque can be increased until it reaches the engine maximum torque. Therefore, the maximum torque that can be output corresponding to the required drive torque is (engine maximum torque) + (motor assist maximum torque).

[0036] When the control shown in Fig. 3 is performed, a delay in the response drive torque of the vehicle 100 with respect to the required drive torque can occur in ranges b and d, as can be seen by comparing graphs 201 and 202 in Fig. 2. Ranges b and d correspond to the ranges in which the engine drive torque is changed in accordance with the accelerator depression amount, as shown in Fig. 3. One cause of this phenomenon is that the response of the engine 101 to a request is slower than the response of the motor 107 and the generator 102 to a request. For example, the engine 101 experiences throttle opening control and intake delay, and such structural factors can cause a delay in the response to a request.

[0037] Therefore, in this embodiment, the delay in response drive torque caused by the engine is taken into consideration and control is performed to improve response compared to conventional control.

[0038] Fig. 4 is a graph illustrating torque transitions during cruise control in the parallel mode according to this embodiment. Fig. 5 is a graph illustrating cruise control according to the amount of operation, corresponding to Fig. 4 . The configurations in Figs. 4 and 5 correspond to the configurations in Figs. 2 and 3, respectively, which show conventional examples. Note that the explanation here uses the amount of accelerator operation (accelerator opening) by the driver as an example, but is not limited to this, and other parameters related to torque control may also be used.

[0039] 4 shows the torque output state, with the vertical axis representing torque value and the horizontal axis representing time. From top to bottom, Fig. 4 shows the drive torque of the vehicle 100, the torque caused by the engine 101, the torque caused by the generator 102, and the torque caused by the motor 107. The sum of the torques shown in the bottom three graphs is the drive torque shown in graph 402.

[0040] Graph 401 shows the required drive torque required for traveling. Meanwhile, graph 402 shows the responsive drive torque. Graph 403 shows the torque caused by the engine 101. Graph 404 shows the torque caused by the generator 102. Graph 405 shows the torque caused by the motor 107. For the generator 102, the range below 0 corresponds to power generation.

[0041] FIG. 5 is a graph illustrating driving control in the parallel mode according to this embodiment. In FIG. 5, the vertical axis represents drive torque, and the horizontal axis represents accelerator depression amount. A solid line 501 represents the required drive torque. A dashed line 502 represents the drive torque due to engine output. In the configuration according to this embodiment, the relationship between engine fuel consumption torque T1, assist start torque T2, and maximum engine torque T3 is also assumed to be T1<T2<T3. Threshold values ​​A and B are also defined in the same way as in the conventional system.

[0042] 5, area 503 indicates engine drive torque from the torque due to the engine output, areas 504 and 507 indicate engine power generation torque from the torque due to the engine output, and areas 505 and 506 indicate motor assist torque from the motor output.

[0043] First, when the accelerator operation amount is in the range from 0 to threshold A (shown as range a'), by operating engine 101 in a fuel-efficient state (i.e., constant engine fuel efficiency torque T1), the required drive torque becomes lower than the engine fuel efficiency torque. Therefore, the difference ((engine fuel efficiency torque) - (required drive torque)) is diverted to power for generating electricity in generator 102 (corresponding to region 504). In other words, when the accelerator operation amount is in the range from 0 to threshold A, torque from the engine output (i.e., engine fuel efficiency torque T1) is used to drive vehicle 100 and charge battery 114 with electricity generated by generator 102.

[0044] When the accelerator operation amount is in the range from threshold A to threshold B' (shown as range b'), the required drive torque exceeds the engine fuel consumption torque T1. However, the engine drive torque is controlled to be constant at engine fuel consumption torque T1, and the motor assist torque increases as the accelerator operation amount increases (corresponding to region 506). Therefore, the required drive torque is provided by the sum of the engine drive torque (i.e., constant at engine fuel consumption torque T1) and the motor assist torque. At this time, as shown by dashed line 408 in FIG. 4, the generator 102 does not generate electricity, and motor output is performed as shown by dashed line 409. Meanwhile, since the engine 101 cannot actually increase torque rapidly as shown in FIG. 5, the torque output is gradually increased as shown by dashed line 406 in FIG. 4. The degree of change in torque output here will be referred to as the "rate of change." The motor assist torque can be output by driving the motor 107 using the power stored in the battery 114 within range a'. The setting of threshold B' will be described later, but it is set to be variable between thresholds A and B.

[0045] When the accelerator operation amount is in the range from threshold B' to threshold B (shown as range c'), the output from engine 101 is increased and operated so as to be constant at assist start torque T2. At this time, the motor assist torque from the motor output is controlled to stop. As a result, the required drive torque becomes lower than the torque from the engine output (i.e., assist start torque T2). Therefore, the difference ((assist start torque T2) - (required drive torque)) is diverted to power for generating electricity in generator 102 (corresponding to region 507). In other words, when the accelerator operation amount is between threshold B' and threshold B, the torque from the engine output (i.e., equivalent to assist start torque T2) is used to drive vehicle 100 and charge battery 114 with electricity generated by generator 102.

[0046] When the accelerator operation amount is in the range from threshold B to threshold C' (shown as range d'), the engine drive torque is controlled to be constant at assist start torque T2, and the motor assist torque increases as the accelerator operation amount increases. Therefore, the required drive torque is provided by the sum of the engine drive torque (i.e., constant at assist start torque T2) and the motor assist torque. The motor assist torque can be output by driving the motor 107 using the power stored in the battery 114 in range a' or range c'. The threshold C' is set to an arbitrary value. For example, the threshold C' is set to a value sufficiently smaller than the operation amount corresponding to (assist start torque T2) + (motor assist maximum torque) so that the motor assist can respond when the required drive torque fluctuates.

[0047] As the accelerator depression amount increases further and exceeds threshold C' (indicated as range e'), the motor assist torque reaches its maximum torque and cannot be increased any further. Therefore, the engine output is increased to maintain the engine maximum torque T3, and the motor assist torque is controlled to match the required drive torque. Since the engine 101 cannot actually increase torque rapidly as shown in FIG. 5 , the torque output is gradually increased as shown by dashed line 407 in FIG. 4 . In response to this, the motor output is increased as shown by dashed line 410 to compensate for the shortfall in the engine output. After the engine output from dashed line 407 reaches the target torque output (i.e., equivalent to engine maximum torque T3), the increase in motor output is returned to its original state. Therefore, the maximum torque that can be output corresponding to the required drive torque is (engine maximum torque) + (motor assist maximum torque).

[0048] As described above, in this embodiment, the engine torque is controlled by switching between three states: engine fuel consumption torque T1, assist start torque T2, and maximum engine torque T3, depending on the accelerator depression amount.

[0049] FIG. 6 is a conceptual diagram illustrating the operation of the ECU 108 according to this embodiment when determining torque during parallel mode driving. As shown in FIG. 1 , the ECU 108 can acquire various state information during driving of the vehicle 100 via various sensors. In this embodiment, the ECU 108 can timely acquire information on the vehicle speed, accelerator operation amount, engine speed, and remaining battery charge (SOC). The ECU 108 can also acquire information on the maximum output of the motor 107 and the maximum battery output of the battery 114. This information may be calculated based on information obtained from the various sensors, or may be acquired from predetermined information. Note that FIG. 6 focuses on the torque determination during parallel mode driving, and therefore some parts of the control flows described later in FIGS. 7 and 8 are overlapped and / or omitted.

[0050] The ECU 108 derives the required driving torque based on the vehicle speed and the accelerator operation amount (step S610). The required driving torque may be derived based on a table that is predefined in association with the vehicle speed and the accelerator operation amount, or may be derived using a predefined calculation formula.

[0051] The ECU 108 derives the engine torque based on the required driving torque derived in step S610, the engine speed, and the remaining battery charge (step S620). In deriving the engine torque, the ECU 108 first determines threshold values ​​B' and C' based on the engine speed and the remaining battery charge (steps S621 and S622). The ECU 108 also derives the engine fuel consumption torque T1, the assist start torque T2, and the engine maximum torque T3 based on the engine speed and the remaining battery charge (steps S623 to S625). The method for deriving the engine fuel consumption torque T1, the assist start torque T2, and the engine maximum torque T3 is not particularly limited, and may be performed by referring to a table that associates the engine speed with the remaining battery charge, or by using a predetermined calculation formula.

[0052] Then, the ECU 108 determines the engine torque using the determined and derived parameters and predetermined conditions (step S626). The conditions for determining the engine torque are defined as follows, based on the configurations described in Figures 4 and 5. Condition 1: If the required driving torque < threshold B', then the first engine torque (here, engine fuel consumption torque T1); Condition 2: If threshold B' ≤ required driving torque < threshold C', then the second engine torque (here, assist start torque T2); Condition 3: If threshold C' ≤ required driving torque, then the third engine torque (here, engine maximum torque T3);

[0053] Furthermore, the ECU 108 calculates the motor assist reserve based on the required drive torque, engine torque, and maximum motor assist value. The maximum motor assist value indicates the maximum torque that the motor 107 can supply as assist torque at a given time. The motor assist reserve indicates the difference between the maximum assist torque that the motor 107 can supply at a given time and the value of the assist torque already being supplied at that time. The ECU 108 then calculates the rate of change of the engine torque from the motor assist reserve (step S627).

[0054] The ECU 108 applies the derived rate of change to the derived engine torque to limit the change in the engine torque output (step S628). The rate of change here corresponds to the gradient of the engine torque indicated by the dashed lines 406 and 407 in Figure 4. Therefore, the higher the rate of change, the more rapidly the engine torque is controlled to change, and the lower the rate of change, the more slowly the engine torque is controlled to change.

[0055] Furthermore, ECU 108 derives the maximum value of motor assist based on the maximum motor value and the maximum battery output (step S630). The maximum value of motor assist derived here is used when deriving the rate of change of engine torque in step S627.

[0056] The ECU 108 subtracts the engine torque calculated in step S620 from the required drive torque calculated in step S610 to calculate the assist torque by the motor 107 (step S640). Then, the ECU 108 controls the motor 107 to output the motor assist torque calculated in step S640.

[0057] The ECU 108 controls the engine 101 so as to output the engine torque calculated in step S610.

[0058] The ECU 108 calculates the difference between the required drive torque calculated in step S610 and the engine torque calculated in step S620 to calculate the power generation torque of the generator 102 (step S650). The ECU 108 then controls the generator 102 to generate power with the power generation torque calculated in step S650.

[0059] [Control Flow] Figure 7 is a flowchart of the control process according to this embodiment. This process flow may be implemented by the ECU 108 reading and executing the program and various data according to this embodiment. In this case, the ECU 108 performs control in cooperation with each part of the vehicle 100 by transmitting and receiving data to and from each part. When this process is performed, it is assumed that the vehicle 100 is in a state where it can run and is running in one of the running modes described above.

[0060] In step S701, the ECU 108 determines whether the current driving mode of the vehicle 100 is the parallel mode. That is, it determines whether the mode allows the vehicle 100 to drive using both the engine 101 and the motor 107 as drive sources. If the mode is the parallel mode (YES in step S701), the process by the ECU 108 proceeds to step S702. On the other hand, if the mode is not the parallel mode (NO in step S701), the process flow ends. In this case, the vehicle 100 continues to drive in a mode other than the parallel mode.

[0061] In step S702, the ECU 108 acquires detected values ​​from various sensors. In this embodiment, at least the speed, accelerator operation amount, engine speed, and remaining battery charge are acquired. Furthermore, the ECU 108 acquires information regarding the maximum output of the motor 107 and the maximum battery output of the battery 114.

[0062] In step S703, the ECU 108 sets each threshold value. In this embodiment, as shown in Fig. 5, threshold values ​​A, B, B', and C' are set. Predefined values ​​are used for threshold values ​​A, B, and C', and threshold value B' is set in the processing flow described later with reference to Fig. 8.

[0063] In step S704, ECU 108 determines whether the accelerator operation amount is smaller than threshold value A. If the accelerator operation amount is smaller than threshold value A (YES in step S704), the process by ECU 108 proceeds to step S705. On the other hand, if the accelerator operation amount is equal to or greater than threshold value A (NO in step S704), the process by ECU 108 proceeds to step S706.

[0064] In step S705, the ECU 108 controls the engine 101 to output a first engine torque, i.e., the engine fuel consumption torque T1. At this time, since the range corresponds to range a' in FIG. 5, the required drive torque is smaller than the engine fuel consumption torque T1, and therefore the generator 102 is also controlled to generate electricity. Then, the process of the ECU 108 proceeds to step S713.

[0065] In step S706, ECU 108 determines whether the accelerator operation amount is smaller than threshold value B'. If the accelerator operation amount is smaller than threshold value B' (YES in step S706), the process by ECU 108 proceeds to step S707. On the other hand, if the accelerator operation amount is equal to or greater than threshold value B' (NO in step S706), the process by ECU 108 proceeds to step S708.

[0066] In step S707, the ECU 108 controls the engine 101 to output a first engine torque, i.e., the engine fuel consumption torque T1. At this time, since the range corresponds to range b' in FIG. 5, the required drive torque is greater than the engine fuel consumption torque T1, and therefore the ECU 108 also controls the engine 101 to provide motor assistance by the motor 107. Then, the process of the ECU 108 proceeds to step S713.

[0067] In step S708, ECU 108 determines whether the accelerator operation amount is smaller than threshold value B. If the accelerator operation amount is smaller than threshold value B (YES in step S708), the process by ECU 108 proceeds to step S709. On the other hand, if the accelerator operation amount is equal to or greater than threshold value B (NO in step S708), the process by ECU 108 proceeds to step S710.

[0068] In step S709, the ECU 108 controls the engine 101 to output a second engine torque, i.e., the assist start torque T2. At this time, since the range corresponds to range c' in FIG. 5, the required drive torque is smaller than the assist start torque T2, and therefore the generator 102 is also controlled to generate electricity. Then, the process of the ECU 108 proceeds to step S713.

[0069] In step S710, ECU 108 determines whether the accelerator operation amount is smaller than threshold value C'. If the accelerator operation amount is smaller than threshold value C' (YES in step S710), the process by ECU 108 proceeds to step S711. On the other hand, if the accelerator operation amount is equal to or greater than threshold value C' (NO in step S710), the process by ECU 108 proceeds to step S712.

[0070] In step S711, the ECU 108 controls the engine 101 to output a second engine torque, i.e., an assist start torque T2. At this time, since the range corresponds to range d' in FIG. 5, the required drive torque is greater than the assist start torque T2, and therefore the ECU 108 also controls the engine 101 to provide motor assist by the motor 107. Then, the process of the ECU 108 proceeds to step S713.

[0071] In step S712, ECU 108 controls engine 101 to output a third engine torque, i.e., maximum engine torque T3. At this time, since the required drive torque corresponds to range e' in FIG. 5 and is greater than maximum engine torque T3, control is also performed to provide motor assist by motor 107. Then, the process of ECU 108 proceeds to step S713.

[0072] In step S713, the ECU 108 derives the motor assist reserve. As shown in FIG. 6 , the maximum value at which the motor 107 can currently assist is first calculated from the maximum value of the motor 107 and the remaining battery power. Then, the remaining motor torque that can currently assist is calculated based on the required drive torque, the maximum motor assist, and the derived engine torque. Note that the remaining power of the battery 114 may also be used as the motor assist reserve.

[0073] In step S714, the ECU 108 determines whether the motor assist reserve is greater than a predetermined threshold X. It is assumed that the threshold X is predetermined. In this embodiment, the greater the motor assist reserve, the lower the change rate of the engine 101 is set. That is, the greater the motor assist reserve, the longer the time required to reach the target engine torque, thereby increasing the load on the motor assist side (consumption of the battery 114). On the other hand, when the motor assist reserve is small, the change rate of the engine 101 is set high and the target engine torque is reached in a shorter time, thereby reducing the load on the motor assist side (consumption of the battery 114). If the motor assist reserve is greater than the threshold X (YES in step S714), the processing by the ECU 108 proceeds to step S715. On the other hand, if the motor assist reserve is equal to or less than the threshold X (NO in step S714), the processing by the ECU 108 proceeds to step S716.

[0074] In step S715, the ECU 108 sets the rate of change of the engine torque to decrease, and executes torque control of the engine 101. In this embodiment, the rate of change of the engine torque is used when switching the engine torque at the timings indicated by the dashed lines 406 and 407 in Fig. 4. Then, the process of the ECU 108 returns to step S701 and repeats the process.

[0075] In step S716, the ECU 108 sets the rate of change of the engine torque to increase, and executes torque control of the engine 101. In this embodiment, the rate of change of the engine torque is used when switching the engine torque at the timings indicated by the dashed lines 406 and 407 in Fig. 4. Then, the process of the ECU 108 returns to step S701 and repeats the process.

[0076] (Threshold Setting Process) Figure 8 is a flowchart of a process for setting the threshold B' according to this embodiment. This process flow is performed, for example, in step S621 in Figure 6 or step S703 in Figure 7. This process flow may be realized by the ECU 108 reading and executing the program and various data according to this embodiment.

[0077] In step S801, the ECU 108 acquires the remaining amount (SOC) of the battery 114 via the battery remaining amount sensor 113.

[0078] In step S802, ECU 108 determines whether the SOC acquired in step S801 is within a predetermined reference range. The reference range is assumed to be predefined corresponding to the maximum capacity of battery 114. Note that although the determination is made using the reference range here, the determination may also be made using a threshold value. If the SOC is within the reference range (YES in step S802), the process by ECU 108 proceeds to step S803. On the other hand, if the SOC is outside the reference range (NO in step S802), the process by ECU 108 proceeds to step S804.

[0079] In step S803, the ECU 108 sets the threshold value B' as the reference value. This reference value may be, for example, the median value between the predetermined threshold values ​​A and B. The median value is a value that matches the engine torque surplus (corresponding to region 506 in FIG. 5) with the engine torque deficiency (corresponding to region 507 in FIG. 5). This achieves a balance between the engine's fuel economy and its responsiveness to requests. Then, this processing flow ends.

[0080] In step S804, ECU 108 determines whether the SOC is higher than the reference range, i.e., whether the SOC is increasing. If the SOC is increasing (YES in step S804), the process by ECU 108 proceeds to step S805. On the other hand, if the SOC is decreasing (NO in step S804), the process by ECU 108 proceeds to step S806.

[0081] In step S805, ECU 108 sets threshold B' to a value closer to threshold B than the reference value, i.e., a value higher than the reference value. The set value here may be a fixed value. Alternatively, it may be determined based on the relationship between the SOC value and the range from threshold A to threshold B, for example, a ratio. Setting threshold B' to a high value increases the frequency of motor assistance, and improves responsiveness by using a sufficiently charged battery 114. Then, this processing flow ends.

[0082] In step S806, ECU 108 sets threshold value B' to a value closer to threshold value A than the reference value, i.e., a value lower than the reference value. A fixed value may be used as the set value here. Alternatively, the set value may be determined based on the relationship between the SOC value and the range from threshold value A to threshold value B, for example, a ratio. Setting threshold value B' to a low value increases the frequency of power generation by generator 102, and can encourage charging of battery 114 with a low SOC. Then, this processing flow ends.

[0083] As described above, this embodiment makes it possible to improve responsiveness to driver requests while performing fuel-efficient driving control in the parallel mode in which the engine and the motor can be used as drive sources.

[0084] Other Embodiments In the above embodiment, an example was described in which the speed is increased by operating the accelerator, but similar control may also be applied when the speed is decreased.

[0085] In the above embodiment, the rate of change is used to suppress abrupt changes in engine torque. In this case, hysteresis may be provided for increasing and decreasing the accelerator operation amount, and the rate of change may be set to any desired range. Therefore, different values ​​may be set for the thresholds B' and C' when increasing and decreasing. By providing hysteresis, for example, when the accelerator operation amount matches or approximately matches the thresholds B' and C', the engine torque request can be controlled to prevent hunting.

[0086] In the above embodiment, the accelerator operation has been described assuming that it is performed by a driver. However, this is not limiting, and the configuration of the present invention may be applied, for example, when an ECU or the like performs accelerator operation in a driving assistance function or an automatic driving function such as an ADAS (Advanced Driver-Assistance Systems) or an ADS (Autonomous Driving System).

[0087] Furthermore, in the present invention, a program or application for realizing the functions of one or more of the above-described embodiments can be supplied to a system or device using a network or a storage medium, etc., and one or more processors in the computer of the system or device can read and execute the program, thereby realizing the present invention.

[0088] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0089] As described above, the present specification discloses the following: (1) A control device (e.g., 108) for a vehicle (e.g., 100) capable of running in a parallel mode using engine drive torque from an engine (e.g., 101) and motor assist torque from a motor (e.g., 107), the control device (e.g., 108) includes a control unit (e.g., 108) that causes the vehicle to run by switching the engine drive torque in stages according to a required drive torque, the control unit switching the engine drive torque from a first torque (e.g., T1) to a second torque (e.g., T2) according to the required drive torque exceeding a first threshold value (e.g., threshold value B'), the first threshold value being set between a first value (e.g., threshold value A) corresponding to a torque at which fuel economy is best achieved by increasing the output from the motor rather than the engine, and a second value (e.g., threshold value B) corresponding to a torque at which fuel economy is better achieved by increasing the output from the motor rather than the engine, The control unit of the vehicle control device is configured to increase the motor assist torque to compensate for the difference between the engine drive torque before and after switching from the first torque to the second torque during a period (e.g., b') required for switching the engine drive torque from the first torque to the second torque. With this configuration, in a parallel mode in which the engine and the motor can be used as drive sources, it is possible to perform fuel-efficient driving control while improving responsiveness to driver requests.

[0090] (2) The control device for a vehicle according to (1), wherein the control unit switches the first threshold value in accordance with a remaining charge of a battery (e.g., 114) for a motor provided in the vehicle. With this configuration, it is possible to switch the timing of assist by the motor in accordance with the remaining charge of the battery.

[0091] (3) The vehicle control device according to (2), wherein the control unit changes the first threshold value to approach the first value when the remaining battery charge is lower than a predetermined value, and changes the first threshold value to approach the second value when the remaining battery charge is higher than the predetermined value. With this configuration, it is possible to adjust the amount of engine drive torque to increase opportunities for charging when the remaining battery charge is low, and to adjust the amount of motor torque to increase opportunities for assist when the remaining battery charge is high.

[0092] (4) The control device for a vehicle according to (1), wherein the control unit further derives a reserve capacity of motor assist torque by the motor, and switches a rate of change of torque when switching the engine drive torque from the first torque to the second torque according to the reserve capacity of the motor assist torque. With this configuration, it is possible to adjust the rate of torque fluctuation of the engine according to the reserve capacity of the motor assist torque.

[0093] (5) The vehicle control device according to (4), wherein the control unit decreases the rate of change when the motor assist torque reserve is greater than a predetermined threshold, and increases the rate of change when the motor assist torque reserve is less than the predetermined threshold. This configuration allows the engine to be controlled to change slowly to achieve a target torque when the motor assist reserve is large, and to change quickly to achieve the target torque when the motor assist reserve is small. As a result, it is possible to improve responsiveness while balancing the load between engine torque switching and motor assist.

[0094] (6) The control device for a vehicle according to (1), wherein the control unit switches the engine drive torque from the second torque to a third torque in response to the required drive torque exceeding a second threshold (e.g., threshold C'), and the third torque is a maximum torque (e.g., T3) that can be output by the engine. With this configuration, it is possible to switch to maximum engine torque in a stepwise manner in response to the required drive torque exceeding a predetermined threshold.

[0095] (7) The vehicle control device according to (6), wherein the second threshold value is set to correspond to a torque smaller than the sum of the maximum torque that can be output by the motor and the second torque. With this configuration, it is possible to set a threshold value for gradually switching the engine torque to the maximum engine torque, taking into account the values ​​of the motor-assisted maximum torque and the engine maximum torque.

[0096] (8) The vehicle control device according to (1), wherein the control unit provides the required drive torque by assisting with the motor assist torque when the engine drive torque is lower than the required drive torque, and adjusts the engine drive torque to the required drive torque by charging a battery when the engine drive torque is higher than the required drive torque. According to this configuration, when the engine drive torque is lower than the required drive torque as a result of switching the engine drive torque in stages, the control unit causes the motor to assist, and when the engine drive torque is higher than the required drive torque, the control unit causes the generator to charge the battery. This makes it possible to compensate for excess or deficiency of engine drive torque and provide appropriate torque while suppressing unnecessary torque consumption.

[0097] Although various embodiments have been described above, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0098] The present invention is applicable to the manufacturing industry of electric vehicles (for example, electric vehicles, hybrid vehicles, and plug-in hybrid vehicles), as well as to the manufacturing industry of control devices mounted on electric vehicles.

[0099] REFERENCE SIGNS LIST 100: Vehicle 101: Engine 102: Generator 103: Engine clutch 104: Drive shaft 105: Drive wheels (front wheels) 106: Motor clutch 107: Motor 108: ECU 109: Accelerator opening sensor 110: Brake sensor 111: Speed ​​sensor 112: Engine rotation sensor 113: Battery remaining capacity sensor 114: Battery 115: Axle 116: Driven wheels (rear wheels)

Claims

1. A control device for a vehicle capable of running in a parallel mode using an engine drive torque from an engine and a motor assist torque from a motor, A control unit is provided for switching the engine drive torque in stages according to the required drive torque, the control unit switches the engine driving torque from a first torque to a second torque in response to the required driving torque exceeding a first threshold value; the first threshold value is set between a first value corresponding to the first torque at which the engine has the best fuel economy and a second value corresponding to the second torque; the control unit assists a difference between the engine driving torque and the required driving torque by increasing the motor assist torque during a period required for switching the engine driving torque from the first torque to the second torque at a predetermined change rate, The control unit provides hysteresis in an increase and decrease in an accelerator operation amount corresponding to the required driving torque, and sets the specified rate of change when switching the engine driving torque at an arbitrary range for each of the increase and decrease.

2. The vehicle control device according to claim 1 , wherein the control unit switches the first threshold value depending on a remaining charge of a battery for a motor provided in the vehicle.

3. The control unit is When the remaining charge of the battery is lower than a predetermined value, the first threshold is changed to approach the first value; The vehicle control device according to claim 2 , wherein when the remaining charge of the battery is higher than the predetermined value, the first threshold value is changed to approach the second value.

4. The control unit further includes: A margin of motor assist torque by the motor is calculated; The vehicle control device according to claim 1 , wherein a rate of change of the engine drive torque when switching the engine drive torque from the first torque to the second torque is switched in accordance with a reserve of the motor assist torque.

5. The control unit is When the motor assist torque margin is greater than a predetermined threshold, the rate of change is decreased. The vehicle control device according to claim 4 , wherein when the motor assist torque reserve is smaller than the predetermined threshold, the rate of change is increased.

6. the control unit switches the engine driving torque from the second torque to a third torque in response to the required driving torque exceeding a second threshold value; The vehicle control device according to claim 1 , wherein the third torque is a maximum torque that can be output by the engine.

7. The vehicle control device according to claim 6 , wherein the second threshold value is set corresponding to a torque smaller than a sum of a maximum torque that can be output by the motor and the second torque.

8. The control unit is When the engine drive torque is lower than the required drive torque, the required drive torque is provided by assisting the engine drive torque with the motor assist torque.

2. The vehicle control device according to claim 1, wherein, when the engine drive torque is higher than the required drive torque, the engine drive torque is adjusted to the required drive torque by charging a battery.