Hybrid vehicle

Abstract

Provided is a vehicle Ve comprising: an engine ENG; a power generation motor GEN capable of generating power with a motive power of the engine ENG and supplying the generated power to a battery BAT; and a main drive motor MOT1 capable of driving front wheels FWR with the power of the power generation motor GEN and the battery BAT. It is possible to set the following: a first mode in which travel is possible by generating power at an arbitrary engine rotation speed Ne; and a second mode in which travel is possible at an engine rotation speed Ne based on a vehicle speed and a pseudo gear shift stage which simulates a gear shift stage. The vehicle comprises: a waste power control unit 100 that executes waste power control for consuming surplus power by rotating the engine ENG by means of the power generation motor GEN when it becomes necessary to consume surplus power that cannot be stored in the battery BAT; and a regeneration control unit 110 that controls, on the basis of a regeneration upper limit value, a regenerative braking force by a regenerative operation of the main drive motor MOT1. The regeneration control unit 110 sets the regeneration upper limit value of the second mode during execution of waste power control to be smaller than the regeneration upper limit value of the first mode during execution of waste power control.

Description

Hybrid vehicle

[0001] The present invention relates to a hybrid vehicle capable of series running.

[0002] In recent years, efforts to realize a low-carbon society or a decarbonized society have been active, and in vehicles as well, research and development on electrification technologies have been carried out in order to reduce CO2 emissions and improve energy efficiency.

[0003] For example, Patent Document 1 describes a series hybrid vehicle including a drive motor that generates drive torque and a power generation motor that generates electricity with the power of an engine and supplies the generated electricity to a battery.

[0004] In a series hybrid vehicle, regenerative control is performed in which a braking torque is generated by a motor and electric power is recovered to a power storage device. However, in regenerative control, when the power storage amount of the power storage device is close to full charge, it is not possible to generate sufficient regenerative braking torque on the drive wheels. Therefore, in the series hybrid vehicle in Patent Document 1, a technique is disclosed in which surplus power is consumed by rotating the engine by a power generation motor simultaneously with regenerative control so that regenerative control can be continued.

[0005] Japanese Patent Application Laid-Open No. 2022-063117

[0006] In a conventional series hybrid vehicle, since the engine speed can be set to an arbitrary speed, surplus power can be consumed somewhat freely. On the other hand, in a vehicle that performs shift control by a pseudo gear stage that simulates gear stages, since the engine speed is uniquely determined for each gear stage in the pseudo gear stage, the amount of electric power that can be consumed by rotating the engine is limited. Therefore, for example, when the power storage amount of the power storage device is close to full charge, if the amount of regeneration by regenerative control becomes larger than the amount of power consumption by rotating the engine, there is a risk that the power storage device cannot be protected, such as overcharging.

[0007] The present invention provides a hybrid vehicle capable of protecting a power storage device when consuming surplus power by rotating an engine by a power generation motor in a vehicle capable of series running.

[0008] One aspect of the present invention is a series-operated hybrid vehicle comprising: an engine; a generator capable of generating electricity with the power of the engine and supplying the generated electricity to a power storage device; and an electric motor capable of driving the drive wheels with the power of the generator and the power storage device, wherein the hybrid vehicle can be set to a first mode in which it can run by generating electricity at any engine speed, and a second mode in which it can run at an engine speed based on a plurality of pseudo-gear stages that simulate gear stages and vehicle speed, and comprises: a waste power control unit that performs waste power control to consume the surplus electricity that cannot be stored in the power storage device by rotating the engine with the generator when it becomes necessary to consume the surplus electricity; and a regenerative control unit that controls the regenerative braking force due to the regenerative operation of the electric motor based on a regenerative upper limit value, wherein the regenerative control unit makes the regenerative upper limit value in the second mode while the waste power control is being performed smaller than the regenerative upper limit value in the first mode while the waste power control is being performed.

[0009] According to the present invention, when surplus electricity is consumed by rotating the engine with a power generation motor, the energy storage device can be protected.

[0010] Figure 1 is a schematic diagram showing an example of the configuration of vehicle Ve. Figure 2 is a diagram showing an example of gear shift settings in pseudo-gear shift mode. Figure 3 is a block diagram showing an example of a control unit (ECU). Figure 4 is a diagram illustrating the regenerative upper limit values ​​for normal mode and pseudo-gear shift mode. Figure 5 is a flowchart showing an example of a control example in the embodiment, in particular an example for determining the start of waste power control. Figure 6 is a flowchart showing an example of a control example in the embodiment, in particular an example for setting the regenerative upper limit value.

[0011] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The following embodiments are not limiting to the present invention, and not all of the elements described in the following embodiments are essential to the present invention. Furthermore, two or more elements described in the following embodiments may be arbitrarily combined without departing from the spirit of the present invention. In the following, identical or similar elements will be denoted by the same or similar reference numerals, and their descriptions may be omitted or simplified.

[0012] [Vehicle] The vehicle targeted in this embodiment is a hybrid vehicle capable of so-called series driving (hereinafter simply referred to as "vehicle"). As shown in Figure 1, the vehicle Ve in this embodiment comprises a mechanically independent main drive unit DU1 and a secondary drive unit DU2. Here, "mechanically independent" means that the power of one is not mechanically transmitted to the other by a propeller shaft or the like. In this embodiment, the main drive unit DU1 outputs a main driving force to drive the front wheels FWR, and the secondary drive unit DU2 outputs a secondary driving force to drive the rear wheels RWR.

[0013] As an example, in this embodiment, the main drive unit DU1 is positioned as the primary drive source in the vehicle Ve, and the secondary drive unit DU2 is positioned as an auxiliary drive source. A relatively large motor is used as the main drive motor MOT1 for the main drive unit DU1, and a smaller motor is used as the secondary drive motor MOT2 for the secondary drive unit DU2 compared to the main drive motor MOT1.

[0014] Vehicle Ve further includes a battery BAT, which is an energy storage device, a voltage control unit VCU, and a control unit ECU.

[0015] A battery (BAT) is a rechargeable secondary battery having multiple energy storage cells connected in series or in series-parallel. A battery (BAT) is configured to output high voltages, such as 100 to 400 [V]. Lithium-ion batteries and nickel-metal hydride batteries can be used as the energy storage cells in a battery (BAT).

[0016] The voltage control unit (VCU) boosts the output voltage from the battery (BAT) while keeping it as DC, and outputs the boosted voltage to the main drive unit (DU1) and the secondary drive unit (DU2). In other words, in vehicle Ve, the boosted voltage generated by a single voltage control unit (VCU) can be supplied to both the main drive unit (DU1) and the secondary drive unit (DU2) in common. The voltage control unit (VCU) may also step down the input voltage input to the battery (BAT). The voltage control unit (VCU) is, for example, a DC-DC converter.

[0017] [Main drive unit] The main drive unit DU1 comprises an engine ENG, a generator motor GEN which is an example of a generator, a main drive motor MOT1 which is an example of an electric motor, a first inverter INV1, a second inverter INV2, and a first transmission mechanism T1.

[0018] An engine is an internal combustion engine such as a gasoline engine or a diesel engine, in which engine power is generated by the combustion of air introduced through an intake passage and engine fuel injected from a fuel injection valve.

[0019] The main drive motor MOT1 and the generator motor GEN are connected to the battery BAT via the voltage control unit VCU, the first inverter INV1, and the second inverter INV2, enabling power supply from the battery BAT and energy regeneration to the battery BAT. In Figure 1, dotted lines indicate power wiring, and dashed lines indicate control signal lines.

[0020] The first inverter INV1 converts DC voltage to AC voltage and supplies three-phase current to the generator motor GEN. The first inverter INV1 also converts the AC voltage generated by the generator motor GEN to DC voltage.

[0021] The second inverter INV2 converts DC voltage to AC voltage and supplies three-phase current to the main drive motor MOT1. Furthermore, the second inverter INV2 converts the AC voltage generated by the main drive motor MOT1 to DC voltage when the vehicle Ve is braking.

[0022] The first transmission mechanism T1 comprises an input shaft 21, a generator motor shaft 23, a counter shaft 25, and a first differential mechanism D1, all of which are arranged parallel to each other.

[0023] The input shaft 21 is arranged coaxially with the crankshaft 12 of the engine ENG. Power from the crankshaft 12 is transmitted to the input shaft 21 via a damper 13. The input shaft 21 is provided with an output gear 32, which constitutes a gear train for driving the generator motor, as will be described later.

[0024] On the input shaft 21, opposite to the engine ENG side, is an output gear 53 which constitutes an engine power transmission gear train that transmits power from the engine ENG. Between the output gear 32 and the output gear 53 on the input shaft 21 is a hydraulic clutch CL which connects the input shaft 21 and the output gear 53 in a detachable manner.

[0025] The generator motor shaft 23 is a double-structured rotating shaft comprising an inner shaft 27 and an outer shaft 29 arranged concentrically with respect to the inner shaft 27 on the outer circumference. On the engine ENG side of the inner shaft 27, there is an input gear 34 that meshes with the output gear 32 on the input shaft 21. The output gear 32 on the input shaft 21 and the input gear 34 on the inner shaft 27 constitute a gear train for driving the generator motor, which transmits power from the input shaft 21 to the inner shaft 27.

[0026] Furthermore, an outer circumferential shaft 29 is installed on the outer diameter side of the inner circumferential shaft 27, approximately in the center, so as to be rotatable relative to it. A generator motor GEN is attached to the inner circumferential shaft 27 on the side opposite to the engine ENG side. The generator motor GEN comprises a rotor R fixed to the inner circumferential shaft 27 and a stator S fixed to a case (not shown) and positioned opposite the outer diameter side of the rotor R.

[0027] The driving force from the input shaft 21 is transmitted to the inner circumferential shaft 27 of the generator motor shaft 23 via a gear train for driving the generator motor. As a result, the rotation of the inner circumferential shaft 27 causes the rotor R of the generator motor GEN to rotate. This allows the driving force from the input shaft 21 to be converted into electricity by the generator motor GEN.

[0028] On the outer circumferential shaft 29, an output gear 52 is provided that meshes with an input gear 54 on the counter shaft 25, which will be described later. On the side opposite to the engine EN side, a main drive motor MOT1 is attached. The main drive motor MOT1 comprises a rotor R fixed to the outer circumferential shaft 29 and a stator S fixed to a case (not shown) and positioned opposite the outer diameter side of the rotor R.

[0029] The output gear 52 on the outer shaft 29 and the input gear 54 on the counter shaft 25 form a motor power transmission gear train for transmitting power from the outer shaft 29 to the counter shaft 25. Therefore, when the outer shaft 29 rotates due to the driving force of the main drive motor MOT1, that rotation is transmitted to the counter shaft 25 via the motor power transmission gear train.

[0030] The counter shaft 25 is provided with, in order from the engine ENG side, an output gear 56 that meshes with the ring gear 58 of the first differential mechanism D1, and an input gear 54 that meshes with the output gear 53 on the input shaft 21 and the output gear 52 on the outer circumferential shaft 29. The output gear 53 on the input shaft 21 and the input gear 54 on the counter shaft 25 constitute an engine power transmission gear train for transmitting power from the input shaft 21 to the counter shaft 25. In addition, the output gear 56 on the counter shaft 25 and the ring gear 58 of the first differential mechanism D1 constitute a final gear train for transmitting the driving force of the counter shaft 25 to the first differential mechanism D1.

[0031] The driving force of the main drive motor MOT1, which is input to the counter shaft 25 via the motor power transmission gear train, and the driving force of the engine ENG, which is input to the counter shaft 25 via the engine power transmission gear train, are output as the main driving force of the main drive unit DU1, transmitted to the first differential mechanism D1 via the final gear train, and then transmitted from the first differential mechanism D1 to the front wheel FWR.

[0032] In this embodiment, the first transmission mechanism T1 of the main drive unit DU1 includes a first transmission mechanism 41 that mechanically connects the generator motor GEN and the engine ENG in a power-transmitting manner, and a second transmission mechanism 42 that mechanically connects the main drive motor MOT1 and the front wheel FWR in a power-transmitting manner. Specifically, the first transmission mechanism 41 consists of an input shaft 21, an output gear 32, an input gear 34, and an inner circumferential shaft 27, and the second transmission mechanism 42 consists of an outer circumferential shaft 29, an output gear 52, an input gear 54, a counter shaft 25, an output gear 56, and a first differential mechanism D1.

[0033] Furthermore, the hydraulic clutch CL is configured to selectively switch between a state in which the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42 is connected and a state in which the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42 is disconnected. That is, by engaging the hydraulic clutch CL, the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42 is mechanically connected, and by releasing the hydraulic clutch CL, the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42 is mechanically disconnected. In the first transmission mechanism T1, the input gear 54 meshes with the output gear 53 on the input shaft 21 and the output gear 52 on the outer shaft 29. Therefore, when the hydraulic clutch CL is engaged, the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42 is mechanically connected, enabling power transmission between the first transmission mechanism 41 and the second transmission mechanism 42. On the other hand, when the hydraulic clutch CL is released, the output gear 53 disengages from the input shaft 21, mechanically interrupting the power transmission path between the first transmission mechanism 41 and the second transmission mechanism 42, making power transmission between the first transmission mechanism 41 and the second transmission mechanism 42 impossible.

[0034] [Subordinate Drive Unit] The subordinate drive unit DU2 comprises a subordinate drive motor MOT2, a third inverter INV3, and a second transmission mechanism T2. The subordinate drive motor MOT2 is connected to the battery BAT via a voltage control unit VCU and a third inverter INV3, enabling power supply from the battery BAT and energy regeneration to the battery BAT. In Figure 1, dotted lines indicate power wiring, and dashed lines indicate control signal lines.

[0035] The second transmission mechanism T2 comprises motor output shafts 26 and 28 arranged parallel to each other, and a second differential mechanism D2.

[0036] The subordinate drive unit DU2 has a third drive gear 62 mounted on one end of the motor output shaft 26 of the subordinate drive motor MOT2 so as to rotate integrally with it. A third driven gear 64 that meshes with the third drive gear 62 and an output gear 66 are mounted on an output shaft 28 that extends parallel to the motor output shaft 26 of the subordinate drive motor MOT2 so as to rotate integrally with the output shaft 28. Therefore, the driving force of the subordinate drive motor MOT2 is transmitted to the output shaft 28 via the third drive gear 62 and the third driven gear 64. The driving force transmitted to the output shaft 28 is then transmitted from the output gear 66 to the rear wheel RWR via the second differential mechanism D2. Conversely, the driving force from the rear wheel RWR is transmitted to the subordinate drive motor MOT2 via the second differential mechanism D2, the output gear 66, the output shaft 28, the third driven gear 64, the third drive gear 62, and the motor output shaft 26.

[0037] Vehicle Ve also includes an accelerator pedal that acquires acceleration and deceleration requests, where the acceleration request to Vehicle Ve increases as the amount of operation increases and decreases as the amount of operation decreases; paddle shifters that shift up or down in the simulated gear shift described later; and a brake pedal (none of which are shown) that acquires deceleration requests to Vehicle Ve.

[0038] [Drive Mode of Main Drive Unit] Next, the drive mode of the main drive unit DU1 will be explained.

[0039] The drive modes of the main drive unit DU1 include an electric drive mode in which the driving force of the main drive motor MOT1 is output as the main driving force, and an engine drive mode in which the driving force of the engine ENG is output as the main driving force. In electric drive mode, the hydraulic clutch CL is released and the driving force of the main drive motor MOT1 is output as the main driving force. Electric drive mode includes EV driving and series driving, which will be described later. In engine drive mode, the hydraulic clutch CL is engaged and the driving force of the engine ENG is output as the main driving force. Engine drive mode includes engine driving, which will be described later.

[0040] <EV Driving (Electric Drive Mode)> In EV driving mode, the engine ENG is deactivated, and the main drive motor MOT1 is driven by electricity supplied from the battery BAT. Specifically, by driving the main drive motor MOT1 with electricity supplied from the battery BAT, the driving force of the main drive motor MOT1 rotates the outer circumferential shaft 29 of the generator motor shaft 23, and this rotation is transmitted to the counter shaft 25 via the motor power transmission gear train. The driving force of the main drive motor MOT1 transmitted in this way is output as the main driving force via the final gear train and the first differential mechanism D1, and transmitted to the front wheels FWR. This enables EV driving.

[0041] <Series Operation (Power Drive Mode)> In series operation, the engine ENG is running, and the power generated by the generator motor GEN drives the main drive motor MOT1. That is, the driving force of the engine ENG is input from the input shaft 21 to the inner shaft 27 via the generator motor drive gear train, causing the inner shaft 27 to rotate. As a result, the rotor R of the generator motor GEN, which is fixed to the inner shaft 27, rotates, and the generator motor GEN generates electricity. At this time, the engine ENG can be operated at any rotational speed Ne. The power generated by the generator motor GEN is supplied to the main drive motor MOT1, and this power drives the main drive motor MOT1. The driving force of the main drive motor MOT1 rotates the outer shaft 29 of the generator motor shaft 23, and this rotation is transmitted to the counter shaft 25 via the motor power transmission gear train. The driving force transmitted by the main drive motor MOT1 in this manner is output as the main driving force via the final gear train and the first differential mechanism D1, and transmitted to the front wheel FWR. This makes it possible to operate in so-called series driving mode, where the driving force of the engine ENG is entirely converted into electricity by the generator motor GEN.

[0042] Furthermore, when the vehicle Ve is decelerating, it performs regenerative driving, recovering energy through the regenerative operation of the main drive motor MOT1. Normally, the regenerated power is stored in the battery BAT, but in cases such as continuous driving downhill, the remaining charge of the battery BAT may exceed a predetermined value, limiting charging to the battery BAT. In such cases, the regenerated power is consumed by waste power control (hereinafter also simply referred to as "waste power control"), which consumes excess power. For example, in waste power control, the regenerated power from the main drive motor MOT1 is not used to charge the battery BAT, but is supplied to the generator motor GEN, and the generator motor GEN is driven, causing the engine GEN to spin freely, that is, by driving the engine GEN along with the regenerated power, the regenerated power is consumed.

[0043] <Engine Driving (Engine Drive Mode)> In engine driving mode, with the hydraulic clutch CL engaged, the driving force of the engine ENG is output as the main driving force and transmitted to the front wheel FWR. That is, by engaging the hydraulic clutch CL, the driving force of the input shaft 21 is transmitted to the counter shaft 25 via the engine power transmission gear train, and then to the front wheel FWR via the final gear train and the first differential mechanism D1. This enables engine driving. Here, since the input shaft 21 and the inner shaft 27 are always connected via the gear train for driving the generator motor, the rotor R of the generator motor GEN rotates in conjunction with the rotation of the inner shaft 27. Therefore, since the generator motor GEN can generate electricity, the generated electricity can rotate the main drive motor MOT1, and so-called parallel driving is also possible, where the driving force of the engine ENG and the driving force of the main drive motor MOT1 are output as the main driving force.

[0044] In addition, as other driving modes in which the driving force characteristics can be changed, the vehicle Ve can be set to a sports mode that enhances the response of acceleration and deceleration and the response of steering operation, a normal mode that emphasizes the balance between the operability of steering operation and acceleration performance, and a comfort mode (or eco mode) that suppresses fluctuations in fuel injection amount, motor torque, etc. so as to achieve fuel-efficient driving. The setting and switching of these sports mode, normal mode, and comfort mode are executed by, for example, an operation of an operation switch (not shown) by the user.

[0045] Further, the vehicle Ve can be set to a pseudo-shifting mode in which the user can select an arbitrary gear stage in the pseudo gear stage. Here, the pseudo gear stage is a gear stage that simulates a gear stage determined based on, for example, the vehicle speed and the accelerator opening degree in a state where the engine ENG and the drive wheels are disengaged. The pseudo-shifting mode can travel at an engine speed Ne based on a plurality of pseudo gear stages and the vehicle speed. That is, the engine speed Ne can be operated by simulating a stepped transmission to travel. As a result, it is possible to produce a pseudo shift change simulating a stepped transmission. FIG. 2 is a diagram showing an example of a shift setting in the pseudo-shifting mode. Here, gear stages from 1st speed to 8th speed simulating stepped shifting can be set. And the driving force characteristics corresponding to each gear stage are set.

[0046] The pseudo-shifting mode is set or its setting is canceled, for example, when the user performs a predetermined shift operation or switch operation. And the switching of the gear stage in the pseudo gear stage is switched, for example, based on the operation of the accelerator pedal or by the operation of paddle shift by the user's operation. Note that the pseudo-shifting mode is not accepted for setting even when the user sets the pseudo-shifting mode when, for example, the temperature of the catalyst is higher than a predetermined temperature (high temperature) or the temperature of the battery BAT is higher than a predetermined temperature (high temperature), considering the durability of the equipment and the like.

[0047] [Control Device] The control device ECU is, for example, a computer that comprehensively controls the entire vehicle Ve and includes a processor that performs various calculations, a storage unit that stores various information such as predetermined maps and programs in a non-transitory storage medium, and an input / output unit (both not shown) that controls the input / output of data between the inside and outside of the control device ECU. For example, the control device ECU is realized by one ECU (Electronic Control Unit) or by a plurality of ECUs cooperating with each other.

[0048] For example, the control device ECU is communicably provided with each inverter INV, voltage control unit VCU, engine ENG, hydraulic clutch CL, etc. For example, the control device ECU controls the output of the engine ENG by controlling the engine ENG, controls the output of the power generation motor GEN by controlling the first inverter INV1, and controls the output of the main drive motor MOT1 by controlling the second inverter INV2.

[0049] The control device ECU executes various programs stored in the storage unit, for example. As described above, the vehicle Ve can travel in a plurality of driving modes. For example, when traveling in the pseudo-shifting mode, since the engine speed Ne is uniquely determined for each gear stage in that pseudo-shifting stage, in the power consumption control, the power that can be consumed by rotating the engine ENG is limited. Therefore, for example, when the power storage amount of the battery BAT is close to full charge, if the regeneration amount by the regeneration control becomes larger than the power consumption amount by rotating the engine ENG, there is a risk that the battery BAT cannot be protected, such as overcharging. Therefore, in the embodiment, when executing the power consumption control during the setting of the pseudo-shifting mode, a predetermined program capable of protecting the battery BAT is executed.

[0050] As functional units realized by the execution of such a program, the control device ECU includes, as shown in FIG. 3, a power consumption control unit 100 and a regeneration control unit 110. In the following, the processes described as being performed by the power consumption control unit 100 and the regeneration control unit 110 are processes realized by the control device ECU.

[0051] The control unit (ECU) receives input from various sensors. For example, it receives input from an accelerator position sensor 120 that detects the amount of operation on the accelerator pedal of the vehicle Ve, a vehicle speed sensor 130 that detects the vehicle speed of the vehicle Ve, a catalyst temperature sensor 140 that detects the temperature of the catalyst, a battery temperature sensor 150 that detects the temperature of the battery BAT, a battery SOC (State of Charge) sensor 160 that detects the amount of charge stored in the battery BAT, an engine water temperature sensor 170 that detects the engine water temperature (coolant), an outside air temperature sensor 180 that detects the outside air temperature, and a shift position sensor 190 that detects the shift position of a shift device such as a paddle shift. The values ​​from the various sensors are not limited to those detected; they may also be obtained by estimation or other means.

[0052] The power waste control unit 100 performs power waste control by rotating the engine ENG with the generator motor GEN when it becomes necessary to consume surplus power that cannot be stored in the battery BAT. In other words, power waste control is performed when the amount of charge stored in the battery BAT is at or above a predetermined value relatively close to full charge. In this embodiment, power waste control is performed when the amount of charge stored is at or above a predetermined value α described later. Note that full charge is not necessarily limited to a state of 100% charge, but may be a predetermined amount of charge (for example, 80% to 90%) that takes into account the deterioration and durability of the battery BAT.

[0053] The regenerative control unit 110 controls the regenerative braking force generated by the regenerative operation of the main drive motor MOT1 during deceleration based on the regenerative upper limit value. The regenerative upper limit value is the upper limit of the amount of regeneration generated by the regenerative operation of the main drive motor MOT1. In this embodiment, the regenerative control unit 110 makes the regenerative upper limit value when a pseudo-speed shift mode is set while drain power control is being performed smaller than the regenerative upper limit value when a pseudo-speed shift mode is not set while drain power control is being performed. This prevents overcharging of the battery BAT and protects the battery BAT.

[0054] Here, we will explain the "regenerative braking limit" in detail. In this embodiment, the regenerative braking limit is set to be different depending on whether the simulated gear shift mode is set or not.

[0055] Figure 4 is a map illustrating the upper limit of regenerative braking. Figure 4(a) is the map for the case where the pseudo-shift mode is not set (referred to here as "normal mode"), and Figure 4(b) is the map for the case where the pseudo-shift mode is set. Note that "normal mode" may include all modes in which the pseudo-shift mode is not set (e.g., series driving, EV driving, engine driving, etc.), but here, in order to explain the upper limit of regenerative braking including the case where power waste control is performed, the normal mode will be assumed to be series driving. In this embodiment, the normal mode is an example of the "first mode," and the pseudo-shift mode is an example of the "second mode."

[0056] First, let's explain the regenerative braking limit in normal mode. The regenerative braking limit is set based on, for example, the vehicle speed and the amount of charge in the battery BAT. The regenerative braking limit increases when the amount of charge in the battery BAT is relatively small (i.e., regeneration becomes easier), and decreases when the amount of charge in the battery BAT is relatively large (i.e., regeneration becomes more difficult). In this embodiment, as shown in Figure 4(a), when the amount of charge in the battery BAT is less than a predetermined value α, the amount of charge in the battery BAT is relatively large compared to a full charge, and the regenerative braking limit is not specifically set; that is, regenerative operation is possible depending on the size of the main drive motor MOT1 motor.

[0057] On the other hand, if the battery BAT's charge level exceeds a predetermined value α, waste power control is performed. In other words, the regenerated power is consumed by waste power. In this case, a regeneration limit is applied to the regeneration limit. In the case of series driving, since the engine speed Ne can be set to a certain extent, the regeneration limit can be set to a value corresponding to the power applied by the generator motor GEN. Thus, in normal mode, the regeneration limit is reduced when waste power control is applied, but because the engine speed Ne can be set arbitrarily, the limit on the upper limit is more lenient compared to when the pseudo-shift mode described later is set.

[0058] Next, we will explain the regenerative braking limit in the pseudo-shift mode. As shown in Figure 4(b), as long as the amount of charge stored in the battery BAT, where waste power control is not being performed, falls below a predetermined value α, no regenerative braking limit is set, similar to the normal mode described above. In other words, regenerative operation is possible depending on the size of the main drive motor MOT1.

[0059] On the other hand, in the pseudo-shift mode, a predetermined regenerative limit is applied when the battery BAT's stored charge is greater than or equal to a predetermined value α and less than a predetermined value β during discharge control. The regenerative limit at this time is, for example, limited to the amount of regeneration corresponding to the accelerator being released. In the pseudo-shift mode, pseudo-shift stages are set, and the engine speed Ne is determined according to each shift stage in the pseudo-shift mode, so the regenerative limit will be more limited compared to the normal mode described above. The amount of regeneration corresponding to the accelerator being released may be the amount of regeneration corresponding to each shift stage in the pseudo-shift mode. For example, the higher the shift stage in the pseudo-shift mode, the greater the amount of regenerative energy due to the accelerator being released. This is because the vehicle speed Ve is usually higher when the shift stage is high, and the regenerative energy is greater. In other words, the regenerative limit may be higher when the vehicle speed is higher than when the vehicle speed is lower. This is because, compared to when the vehicle speed is low, the engine speed Ne is higher, resulting in a greater amount of wasted electricity, and consequently, an increase in the amount of regenerative braking.

[0060] Furthermore, for example, in a simulated gear shift, at the same vehicle speed, the engine speed increases as the gear ratio decreases (see Figure 2). In other words, at the same vehicle speed, the engine speed Ne increases as the gear ratio decreases, and the amount of wasted electricity increases, so regeneration is easier in lower gears. For this reason, the upper limit of regeneration at the same vehicle speed can be higher as the gear ratio decreases.

[0061] In the simulated shift mode, when the battery BAT's charge level exceeds a predetermined value β, a greater regenerative braking limit is applied during discharge control. In this case, regeneration is prohibited, meaning the regenerative braking amount is set to "0". Note that the predetermined value β may be closer to a fully charged value. Thus, in the simulated shift mode, the regenerative braking limit during discharge control is more restrictive than when the simulated shift mode is not set, and the regenerative braking limit is further reduced in stages depending on the battery BAT's charge level. In other words, during discharge control, the regenerative braking limit when the simulated shift mode is set is smaller than in the normal mode when the simulated shift mode is not set.

[0062] [Flowchart] Next, an example of control performed by the control unit ECU described above will be explained. Figures 5 and 6 show an example of the flowchart. Figure 5 is the process for determining the start of the drain control described above, and Figure 6 is the process for setting the regenerative upper limit described above. As described above, in both the normal mode and the pseudo-shift mode, the regenerative upper limit is limited during drain control. Therefore, for example, the processes in Figure 5 and Figure 6 are executed in parallel, and when the regenerative upper limit is set in the process in Figure 6, if drain control is being performed by the process in Figure 5, the regenerative upper limit corresponding to the drain control will be set. The details of the process will be explained below.

[0063] First, an example of control for determining the start of the power drain control shown in Figure 5 will be explained. As described above, power drain control is performed when the amount of charge stored in the battery BAT is equal to or greater than a predetermined value α. Therefore, in step S1, the control unit ECU determines whether the current amount of charge stored in the battery BAT is equal to or greater than a predetermined value α. The amount of charge stored in the battery BAT may be based on a value obtained from, for example, the battery SOC sensor 160.

[0064] In step S1, if it is determined that the amount of charge stored in the battery BAT is equal to or greater than a predetermined value α (Yes in step S1), the control unit ECU proceeds to step S2.

[0065] In step S2, the control unit (ECU) performs power waste control. That is, it uses the generator motor (GEN) to rotate the engine (ENG) and consume the regenerated power. If, in step S1, it is determined that the amount of charge in the battery (BAT) is less than a predetermined value α (No in step S1), the system returns to the previous state.

[0066] Next, we will explain an example of control for setting the regenerative upper limit in Figure 6. First, in step S10, the control unit ECU determines whether the pseudo-shift mode is set. For example, if the pseudo-shift mode switch is turned on, it is determined that the pseudo-shift mode is set. If it is determined that the pseudo-shift mode is set (Yes in step S10), the control unit ECU proceeds to step S11. If it is determined that the pseudo-shift mode is not set (No in step S10), it is determined that the system is in normal mode, and the control unit ECU proceeds to step S13. Step S11 will be explained first.

[0067] In step S11, the control unit (ECU) obtains the current gear in the simulated gear shift. That is, it obtains information on which of the 1st to 8th gears of the simulated gear shift is set.

[0068] Next, in step S12, the control unit ECU sets the regenerative upper limit value in the simulated gear shift mode. Here, in setting the regenerative upper limit value, the control unit ECU grasps the current state of the vehicle Ve. That is, through the process of determining the start of the power drain control described in Figure 5, which is executed in parallel with Figure 6, it obtains information on whether the current state of the vehicle Ve is during power drain control.

[0069] When the vehicle Ve is in the state of power drain control, the control unit ECU sets the regenerative upper limit value as the regenerative upper limit value for power drain control in the pseudo-gear shift mode. Specifically, the control unit ECU refers to the map in Figure 4(b) above and sets the regenerative upper limit value for power drain control. When power drain control is performed in the pseudo-gear shift mode, the regenerative upper limit value may change depending on whether the battery BAT's charge level is between a predetermined value α and a predetermined value β, or above a predetermined value β. Therefore, the control unit ECU also takes into account the current battery BAT's charge level when setting the regenerative upper limit value. That is, when the battery BAT's charge level is between a predetermined value α and a predetermined value β, the control unit ECU sets the regenerative upper limit value to the amount of regeneration corresponding to the accelerator off in step S11. On the other hand, when the battery BAT's charge level is above a predetermined value β, the control unit ECU sets the regenerative upper limit value to "0" to prohibit regeneration.

[0070] Furthermore, if the vehicle's Ve state is not under power drain control, the control unit (ECU) will not set a regenerative braking limit.

[0071] If it is determined in step S10 above that the pseudo-gear shift mode is not set, the control unit ECU sets the regenerative upper limit in normal mode in step S13. Here, in setting the regenerative upper limit in normal mode, similar to setting the regenerative upper limit in the pseudo-gear shift mode, the control unit ECU grasps the current state of the vehicle Ve. That is, the process of determining the start of the power drain control, as explained in Figure 5 and executed in parallel with Figure 6, obtains information on whether the current state of the vehicle Ve is during power drain control.

[0072] When the vehicle Ve is in the state of power drain control, the control unit ECU sets the regenerative upper limit to the same value as the regenerative upper limit during power drain control in normal mode. Specifically, the control unit ECU refers to the map in Figure 4(a) above and sets the regenerative upper limit during power drain control. In other words, the control unit ECU sets the regenerative upper limit to the value corresponding to the power applied by the generator motor GEN that rotates the engine ENG. If the vehicle Ve is not in the state of power drain control, the control unit ECU does not set a regenerative upper limit.

[0073] As described above, in this embodiment, the regenerative upper limit in the pseudo-gear shift mode during power drain control is set to be smaller than the regenerative upper limit in the normal mode during power drain control. This prevents the amount of regeneration from exceeding the amount of power consumed during power drain control in the pseudo-gear shift mode, thereby preventing overcharging of the battery and protecting the battery.

[0074] Furthermore, the amount of electricity consumed can vary depending on engine friction, etc., but even in such cases, limiting the regeneration limit can suppress overcharging of the battery and protect the battery.

[0075] Although embodiments of the present invention have been described above with reference to the drawings, it goes without saying that the present invention is not limited to the embodiments described above. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these are also understood to naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined arbitrarily without departing from the spirit of the invention.

[0076] For example, in the above embodiment, series driving was described as an example of a normal mode. However, as mentioned above, the normal mode may include all modes in which a pseudo-shift mode is not set, and therefore includes EV driving and engine driving. Accordingly, the setting of the regenerative upper limit, other than during waste power control, may be applied during EV driving and engine driving.

[0077] This specification contains at least the following information. Note that the components etc. in parentheses indicate those corresponding to the embodiments described above, but are not limited thereto.

[0078] (1) A hybrid vehicle (vehicle Ve) capable of series driving, comprising: an engine (engine ENG); a generator (generating motor GEN) capable of generating electricity with the power of the engine and supplying the generated electricity to a battery (battery BAT); and an electric motor (main drive motor MOT1) capable of driving the drive wheels (front wheels FWR) with the power of the generator and the battery, wherein the hybrid vehicle can be set to a first mode in which it is possible to drive by generating electricity at any engine speed, and a second mode in which it is possible to drive at an engine speed based on a plurality of pseudo-gear stages that simulate gear stages and vehicle speed, and comprises: a waste power control unit (waste power control unit 100) that performs waste power control to consume the surplus electricity by rotating the engine with the generator when it becomes necessary to consume the surplus electricity that cannot be stored in the battery, and a regenerative control unit (regenerative control unit 110) that controls the regenerative braking force by the regenerative operation of the electric motor based on a regenerative upper limit value, wherein the regenerative control unit A hybrid vehicle that makes the regenerative upper limit in the second mode while the aforementioned power waste control is being performed smaller than the regenerative upper limit in the first mode while the aforementioned power waste control is being performed.

[0079] According to (1), during waste power control, it is possible to suppress the amount of regenerated energy from exceeding the amount of energy consumed due to waste power, and as a result, it is possible to prevent overcharging of the energy storage device and, consequently, protect the energy storage device.

[0080] (2) A hybrid vehicle as described in (1), wherein the regenerative upper limit is set based on the vehicle speed and the amount of charge stored in the energy storage device.

[0081] According to (2), the regenerative braking limit is set based on the vehicle speed and the amount of stored energy. For example, the regenerative braking limit can be restricted when the vehicle is not being discharged, and not restricted when it is not being discharged. In other words, it becomes possible to set a regenerative braking limit according to the state of the vehicle.

[0082] (3) A hybrid vehicle as described in (2), wherein the regenerative upper limit in the second mode while the waste power control is being performed is greater when the vehicle speed is higher than when the vehicle speed is lower.

[0083] According to (3), when the vehicle speed is high, the engine speed can be increased compared to when the vehicle speed is low, and the amount of waste electricity can be increased. As a result, the amount of regeneration can be increased.

[0084] (4) A hybrid vehicle as described in (2), wherein the regenerative upper limit in the second mode while the waste power control is being executed is set to a value such that the regenerative operation in the second mode is not performed when the amount of energy stored in the energy storage device is equal to or greater than a predetermined value.

[0085] According to (4), by restricting the regenerative operation to not be performed when the amount of stored energy is close to a full charge or above a predetermined value, the storage device will not be charged based on the regenerative operation, thus protecting the storage device.

[0086] (5) A hybrid vehicle according to (1) or (2), wherein the regenerative upper limit in the second mode is set for each gear of the simulated gear.

[0087] According to (5), by setting a regenerative upper limit for each gear of the simulated gear, it is possible to achieve an appropriate amount of regeneration compared to, for example, setting a uniform regenerative upper limit regardless of the gear, and as a result, the balance of energy storage can be improved.

[0088] (6) A hybrid vehicle as described in (5), wherein the regenerative upper limit is set to a larger value the lower the pseudo-gear step is, at the same vehicle speed.

[0089] According to (6), at the same vehicle speed, the engine speed increases when the vehicle is in a low gear, so the amount of electricity consumed by waste electricity increases, and as a result, the amount of regeneration can be increased.

[0090] 100 Waste Power Control Unit 110 Regenerative Control Unit BAT Battery (Energy Storage Device) ENG Engine FWR Front Wheel GEN Generator Motor (Generator) MOT1 Main Drive Motor (Electric Motor) Ve Vehicle (Hybrid Vehicle)

Claims

1. A hybrid vehicle capable of series driving, comprising: an engine; a generator capable of generating electricity with the power of the engine and supplying the generated electricity to a power storage device; and an electric motor capable of driving the drive wheels with the power of the generator and the power storage device, wherein the hybrid vehicle can be set to a first mode in which it can drive by generating electricity at any engine speed and a second mode in which it can drive at an engine speed based on a plurality of pseudo-gear stages that simulate gear stages and vehicle speed, and comprises: a waste power control unit that performs waste power control to consume the surplus electricity that cannot be stored in the power storage device by rotating the engine with the generator when it becomes necessary to consume the surplus electricity; and a regenerative control unit that controls the regenerative braking force by the regenerative operation of the electric motor based on a regenerative upper limit value, wherein the regenerative control unit makes the regenerative upper limit value in the second mode in which the waste power control is being performed smaller than the regenerative upper limit value in the first mode in which the waste power control is being performed.

2. A hybrid vehicle according to claim 1, wherein the regenerative upper limit is set based on the vehicle speed and the amount of charge stored in the energy storage device.

3. A hybrid vehicle according to claim 2, wherein the regenerative upper limit in the second mode during the execution of the waste power control is greater when the vehicle speed is higher than when the vehicle speed is lower.

4. A hybrid vehicle according to claim 2, wherein the regenerative upper limit in the second mode while the waste power control is being executed is set to a value that does not perform the regenerative operation in the second mode when the amount of energy stored in the energy storage device is equal to or greater than a predetermined value.

5. A hybrid vehicle according to claim 1 or 2, wherein the regenerative upper limit in the second mode is set for each gear of the simulated gear.

6. A hybrid vehicle according to claim 5, wherein the regenerative upper limit is set to a larger value the lower the pseudo-gear step is, at the same vehicle speed.

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