Brake force control system for hybrid vehicles

Abstract

To provide a braking force control device of a hybrid vehicle that can suppress deceleration of the vehicle from varying in accordance with a restricted amount of torque of a motor that outputs regenerative torque.SOLUTION: A braking force control device of a hybrid vehicle which comprises a differential mechanism in which an internal combustion engine, a first motor, and a driving wheel are connected to one another to be differentially rotatable, and a second motor connected to the driving wheel, further comprises a controller that controls regenerative torque of the second motor on the basis of an operation amount of an accelerator device. The controller sets maximum regenerative torque (a dashed line) of the second motor in a range in which the operation amount of the accelerator device is less than a predetermined amount, to be equal to or less than a value obtained by subtracting cancel torque Tm_c for canceling torque transmitted to the driving wheel when stopping the internal combustion engine by outputting torque from the first motor, from restricted torque (a bold solid line) in a case where the regenerative torque of the second motor is mostly restricted.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a device for controlling a braking force of a hybrid vehicle including an internal combustion engine and a motor. [Background Art]

[0002] Patent Document 1 describes a vehicle control device capable of setting a so-called one-pedal mode configured such that when an accelerator operation amount is in a region less than a predetermined amount, a greater deceleration is set as the accelerator operation amount is smaller, and when the accelerator operation amount is in a region equal to or greater than the predetermined amount, a greater acceleration is set as the accelerator operation amount is larger. This control device is configured to set a correction amount of a larger value as a gradient of a downhill road is larger, obtain a gradient correction ratio based on a shift position of a paddle shift device operated by a driver, and determine a final deceleration by adding a gradient correction amount obtained by multiplying the correction amount by the gradient correction ratio to a deceleration based on the accelerator operation amount. The control device is configured to control an engine, a motor, or a brake device in accordance with the final deceleration. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2020-100349 [Summary of Invention] [Problem to be Solved by the Invention]

[0004] Incidentally, in a hybrid vehicle equipped with a differential mechanism in which the engine, a first motor, and drive wheels are differentially rotatably connected, and a second motor connected to the drive wheels in a torque-transmitting manner, the second motor can output regenerative torque to enable deceleration. Furthermore, in such a hybrid vehicle, when torque is output from the first motor to stop the engine, the engine's inertia shaft acts as a reaction force, and a portion of the torque output from the first motor is transmitted to the output shaft as driving torque. Therefore, in order to suppress changes in the vehicle's behavior, the second motor may output regenerative torque that counteracts the driving torque. Consequently, in the above hybrid vehicle, when deceleration is being performed by outputting regenerative torque from the second motor, if there is a request to stop the engine, in addition to the regenerative torque for deceleration, the second motor will output regenerative torque to suppress changes in the vehicle's behavior.

[0005] On the other hand, in a hybrid vehicle configured as described above, if a one-pedal mode can be set, as in the vehicle described in Patent Document 1, the deceleration when the accelerator is released will be greater than in a so-called conventional vehicle, and therefore the regenerative torque required of the second motor will be greater. However, the limit of the regenerative torque of the second motor fluctuates due to various factors. Therefore, when the engine is stopped during deceleration driving, the deceleration that can be generated when the limit of the regenerative torque of the second motor is relatively small may differ from the deceleration that can be generated when the limit of the regenerative torque of the second motor is relatively large. In such cases, the deceleration that can be generated by the vehicle will differ depending on conditions that the driver cannot perceive, and the driver may feel uncomfortable.

[0006] The present invention has been made in view of the above technical problems, and aims to provide a braking force control device for a hybrid vehicle that can suppress changes in the vehicle's deceleration according to the torque limit of the motor that outputs regenerative torque. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a braking force control device for a hybrid vehicle comprising a differential mechanism in which an internal combustion engine, a first motor, and a drive wheel are differentially rotatably connected, and a second motor connected to the drive wheel or another drive wheel different from the drive wheel, the device comprising an accelerator operated by the driver, and a power supply connected to the second motor. The device has a converter that boosts the voltage of the power supply and applies it to the second motor, and The system includes a power control unit that converts the power exchanged between the power source and the second motor, and a controller that controls the regenerative torque of the second motor based on the amount of operation of the accelerator device when the amount of operation of the accelerator device is less than a predetermined amount, wherein the controller is controlled by the outside air The pressure is relatively high, or before Note: Power control unit temperature When the boost voltage by the converter is limited to a predetermined first voltage due to a relatively low degree, the output from the second motor is limited to a predetermined first voltage. The first limiting torque set and When the boost voltage from the converter is limited to a predetermined second predetermined voltage that is smaller than the first predetermined voltage due to the relatively low external air pressure or the relatively high temperature of the power control unit, the output voltage from the second motor is limited to the first predetermined voltage. Less than the first limiting torque The predetermined number 2 Limiting torque and any one of the two limiting torques Furthermore, the regenerative torque of the second motor is controlled based on the external air pressure or the temperature of the power control unit. The device is configured to limit the operation of the accelerator, and the maximum regenerative torque of the second motor in the region where the amount of operation of the accelerator device is less than a predetermined amount is set to be less than or equal to the amount obtained by subtracting a cancellation torque from the second limiting torque of the second motor, which is used to offset the torque transmitted to the drive wheels in the direction that drives the hybrid vehicle by outputting torque from the first motor and stopping the internal combustion engine.

[0008] In the present invention, the internal combustion engine is prohibited from stopping in a region where the vehicle speed is above a predetermined speed, and the controller controls the maximum regenerative torque of the second motor in a region below the predetermined speed. In the region, the 2nd system The value may be set to a magnitude less than or equal to the amount obtained by subtracting the cancellation torque from the limit torque.

[0009] In the present invention, the controller is configured to set at least two deceleration modes: a strong deceleration mode in which the maximum regenerative torque of the second motor is relatively large in the region where the amount of operation of the accelerator device is less than a predetermined amount, and a weak deceleration mode in which the maximum regenerative torque is relatively small, and the maximum regenerative torque in the strong deceleration mode is set 2nd system The torque may be set to a value less than or equal to the amount obtained by subtracting the cancellation torque from the limit torque, and greater than or equal to the maximum regenerative torque in the weak deceleration mode. [Effects of the Invention]

[0011] According to the present invention, the maximum regenerative torque of the second motor in the region where the accelerator pedal operation is less than a predetermined amount is set to a magnitude less than or equal to the amount obtained by subtracting the cancellation torque used to offset the torque transmitted to the drive wheels when the internal combustion engine stops from the limiting torque when the regenerative torque of the second motor is most restricted. Therefore, it is possible to suppress situations in which the deceleration differs between when the limiting amount of the regenerative torque of the second motor is large and when the limiting amount of the regenerative torque of the second motor is small. As a result, it is possible to suppress changes in the behavior of the hybrid vehicle in response to the accelerator pedal operation amount depending on whether or not factors that the driver cannot perceive occur, and to suppress the driver from feeling any discomfort. [Brief explanation of the drawing]

[0012] [Figure 1] This is a skeleton diagram illustrating an example of a hybrid vehicle in an embodiment of the present invention. [Figure 2] This is a collinear diagram illustrating the operating states of the engine, the first motor, and the second motor during the engine shutdown process. [Figure 3] This diagram shows an example of a map that defines the maximum regenerative torque for each deceleration mode. [Figure 4] This is an enlarged view of section IV in Figure 3. [Modes for carrying out the invention]

[0013] The present invention will be described based on the embodiments shown in the figures. The embodiments described below are merely examples of how the present invention can be implemented and do not limit the present invention.

[0014] Fig. 1 shows an example of a hybrid vehicle (hereinafter referred to as "vehicle") according to an embodiment of the present invention. This vehicle Ve includes an engine (ENG) 1, a first motor (MG1) 2, and a second motor (MG2) 3 as driving force sources. Note that the engine 1 corresponds to the "internal combustion engine" in the embodiment of the present invention.

[0015] The engine 1 can be configured similarly to a conventional gasoline engine or diesel engine, and is configured to generate torque by combusting a mixture of supplied air and fuel.

[0016] Additionally, each of the motors 2 and 3, similar to motors serving as driving force sources provided in conventional electric vehicles and hybrid vehicles, in addition to functioning as a motor that outputs driving torque when energized with electric power, also has a function as a generator that generates electric power when rotated by input torque. Specifically, it is configured by a permanent magnet synchronous motor, an induction motor, or the like.

[0017] An input shaft 6 of a power split device 5 is connected to an output shaft 4 of the engine 1. This power split device 5 corresponds to the "differential mechanism" in the embodiment of the present invention, and is a differential mechanism configured to split the torque of the input shaft 6 between the first motor 2 and driving wheels 7. In the example shown in Fig. 1, it is configured by a single pinion type planetary gear mechanism. That is, it is configured by a sun gear 8, a ring gear 9 arranged concentrically with the sun gear 8, a plurality of pinion gears 10 meshing with the sun gear 8 and the ring gear 9 and arranged along the circumferential direction of the input shaft 6, and a carrier 11 that holds each pinion gear 10 to be revolvable around the rotation center axis of the input shaft 6 and holds each pinion gear 10 to be rotatable on its own axis. The input shaft 6 is connected to the carrier 11, and the first motor 2 is connected to the sun gear 8.

[0018] An output gear 12 is formed on the outer peripheral surface of the ring gear 9, and a driven gear 13 meshes with the output gear 12. The driven gear 13 is attached to one end of a counter shaft 14 disposed parallel to the input shaft 6, and a counter drive gear 15 is attached to the other end of the counter shaft 14. A ring gear 17 of a differential gear unit 16 meshes with the counter drive gear 15, and left and right drive wheels 7 are coupled to the differential gear unit 16. For convenience, only one drive wheel 7 is shown in Fig. 1.

[0019] A drive gear 18 having a smaller diameter than the driven gear 13 further meshes with the driven gear 13, and the second motor 3 is coupled to the drive gear 18. That is, a drive gear 20 is attached to the tip of an output shaft 19 of the second motor 3. The configuration is not limited to one in which the second motor 3 is coupled to the drive wheels 7 to which torque is transmitted from the engine 1, and the second motor may be coupled to another drive wheel different from the drive wheels 7.

[0020] The aforementioned first motor 2 and second motor 3 are connected to a power storage device (power source) 22 formed of a secondary battery via a power control unit (hereinafter referred to as PCU) 21 provided with a converter and an inverter. Therefore, when outputting torque from the first motor 2 or the second motor 3, the PCU 21 boosts the output voltage of the power storage device 22 to a voltage corresponding to the torque output from the first motor 2 or the second motor 3, and converts the DC voltage output from the power storage device 22 into an AC voltage having a frequency corresponding to the rotation speeds of the first motor 2 and the second motor 3.

[0021] Furthermore, an electronic control unit (hereinafter referred to as ECU) 23 is provided to control the engine 1 and the PCU 21. Similar to ECUs installed in conventional vehicles, this ECU 23 is mainly composed of a microcomputer and receives signals from various sensors installed in the vehicle Ve. Based on these input signals and pre-stored maps and calculation formulas, it determines the control amount for the engine 1 and PCU 21, and outputs signals to the engine 1 and PCU 21 corresponding to the determined control amount.

[0022] Sensors connected to the ECU23 include, for example, an accelerator pedal position sensor (not shown) for detecting the amount of accelerator pedal operation, a brake sensor for detecting the amount of brake pedal operation, a vehicle speed sensor for detecting the vehicle speed of the vehicle Ve, a crank angle sensor for detecting the rotation angle (and rotation speed) of the engine 1, a first rotation speed sensor for detecting the rotation speed of the first motor 2, a second rotation speed sensor for detecting the rotation speed of the second motor 3, a state of charge (SOC) sensor for detecting the remaining charge of the energy storage device 22, a battery temperature sensor for detecting the temperature of the energy storage device 22, a first temperature sensor for detecting the temperature of the first motor 2, a second temperature sensor for detecting the temperature of the second motor 3, an HV water temperature sensor for detecting the temperature of the coolant that cools the PCU21, a pressure sensor for detecting the outside air pressure, and a mode switch for setting the deceleration mode. In Figure 1, for convenience, it is shown as a single sensor 24.

[0023] The ECU23 described above corresponds to the "controller" in the embodiment of the present invention and is configured to control the acceleration (driving torque) and deceleration (braking torque) of the vehicle Ve based on the amount of operation of the accelerator pedal (accelerator device). That is, when the amount of operation of the accelerator pedal is less than a predetermined amount, the smaller the amount of operation, the greater the deceleration can be set, and when the amount of operation of the accelerator pedal is equal to or greater than the predetermined amount, the larger the amount of operation, the greater the acceleration can be set.

[0024] Furthermore, the system is configured to allow setting multiple deceleration modes, each with a different maximum deceleration when the accelerator is released, depending on the driver's operation of the mode switch. Specifically, it is configured to allow setting a strong engine braking mode, which has the largest maximum deceleration when the accelerator is released; a weak engine braking mode, which has the smallest maximum deceleration when the accelerator is released; and a medium engine braking mode, which has a maximum deceleration between the strong and weak engine braking modes. The strong engine braking mode corresponds to the "strong deceleration mode" in the embodiment of the present invention, and the medium engine braking mode corresponds to the "weak deceleration mode" in the embodiment of the present invention.

[0025] The deceleration in the weak engine braking mode described above is set to approximate the deceleration characteristics of the B (brake) range in a conventional vehicle. In other words, the strong engine braking mode and medium engine braking mode are configured to produce deceleration equivalent to the deceleration that would be produced by braking in a conventional vehicle. That is, the strong engine braking mode and medium engine braking mode function in the same way as the conventional one-pedal mode.

[0026] The deceleration described above is configured to be determined based on the accelerator pedal input and vehicle speed, and the ECU 23 stores a map for determining the regenerative torque according to the deceleration mode. Therefore, the ECU 23 determines the braking torque required for the vehicle Ve based on the signals input from the accelerator pedal position sensor, mode switch, and vehicle speed sensor, and the map, and outputs a signal to the PCU 21 for outputting that braking torque from the second motor 3. In other words, the PCU 21 increases the output voltage of the energy storage device 22 to an applied voltage corresponding to the braking torque (regenerative torque) required for the second motor 3.

[0027] Furthermore, since the aforementioned vehicle Ve can run by outputting drive torque and braking torque from the second motor 3, the rotation of engine 1 can be stopped while running. When stopping the rotation of engine 1 in this way, torque is output from the first motor 2 to stop engine 1 in order to shorten the period during which the rotation speed resonates with the natural frequencies of engine 1, power split mechanism 5, etc.

[0028] Figure 2 shows a collinear diagram illustrating the operating states of engine 1 (carrier 11), first motor 2 (sun gear 8), and second motor 3 (ring gear 9) during the engine 1 shutdown process. In Figure 2, the torque of the first motor 2 is denoted as Tg, and the torque of the second motor 3 is denoted as Tm. In the following explanation, the rotation direction in the same direction as engine 1 is referred to as "forward rotation," and the opposite direction is referred to as "negative rotation."

[0029] As shown in Figure 2, when engine 1 is stopped, in the region where the engine speed is above a predetermined speed, the first motor 2 rotates in the forward direction and outputs torque in a direction that decreases its rotational speed. In the region where the engine speed is below the predetermined speed, the first motor 2 rotates in the negative direction, and as the engine speed decreases, the negative rotational speed of the first motor 2 increases.

[0030] As described above, when the first motor 2 outputs torque to reduce the engine speed, a torque Tep corresponding to the inertia torque of the engine 1 is transmitted to the ring gear 9. This torque Tep transmitted to the ring gear 9 acts in a direction that drives the vehicle Ve.

[0031] Therefore, in order to suppress the reduction in deceleration caused by the torque Tep transmitted to the ring gear 9, the second motor 3 is required to have a regenerative torque Tm which is the sum of a braking torque Tm_b for generating deceleration determined based on the accelerator opening and a cancellation torque Tm_c for offsetting the torque transmitted to the ring gear 9.

[0032] On the other hand, in order to protect the components of the PCU21, the limit value of the boost voltage of the PCU21 fluctuates according to the ambient pressure and the temperature of the PCU21. Specifically, the lower the ambient pressure, the higher the limit value of the boost voltage of the PCU21, and the lower the voltage that can be applied from the PCU21 to the second motor 3. In other words, the regenerative torque that the second motor 3 can output decreases. Similarly, the higher the temperature of the PCU21, specifically the temperature detected by the HV water temperature sensor, the higher the limit value of the boost voltage of the PCU21, and the lower the voltage that can be applied from the PCU21 to the second motor 3. In other words, the regenerative torque that the second motor 3 can output decreases.

[0033] Therefore, the braking force control device in the embodiment of the present invention is configured to determine the maximum regenerative torque of the second motor 3 in strong engine braking mode based on the lowest maximum boost voltage of the PCU 21 and the cancellation torque when the engine is stopped.

[0034] Figure 3 shows an example of a map defining the maximum regenerative torque for each deceleration mode, with vehicle speed on the horizontal axis and the regenerative torque of the second motor 2 on the vertical axis. The maximum regenerative torque in strong engine braking mode (hereinafter referred to as strong regenerative torque) is shown by a dashed line, the torque obtained by adding the cancellation torque to the strong regenerative torque (hereinafter referred to as maximum required torque) is shown by a solid line, the maximum regenerative torque in medium engine braking mode (hereinafter referred to as medium regenerative torque) is shown by a dashed line, and the maximum regenerative torque in weak engine braking mode (hereinafter referred to as weak regenerative torque) is shown by a dashed line. Furthermore, the regenerative torque when the maximum voltage is applied to the second motor 3 when the boost voltage limit is at its lowest (i.e., when the applied voltage is at its maximum) is shown by a thick dotted line (VH maximum), and the regenerative torque when the maximum voltage is applied to the second motor 3 when the boost voltage limit is at its highest (i.e., when the applied voltage is at its minimum) is shown by a thick dotted line. solid line This is indicated as (when VH is limited).

[0035] As mentioned above, the cancellation torque Tm_c is constant regardless of vehicle speed because its magnitude corresponds to the inertia torque of engine 1. Therefore, Figure 3 to break The difference between the strong regenerative torque, shown by the line, and the maximum required torque, shown by the solid line, is kept constant. Furthermore, the medium regenerative torque is set to a first predetermined ratio of the strong regenerative torque between the first predetermined vehicle speed V1 and the second predetermined vehicle speed V2, and the weak regenerative torque is set to a second predetermined ratio of the medium regenerative torque between the first predetermined vehicle speed V1 and the third predetermined vehicle speed V3.

[0036] Figure 4 shows an enlarged view of section IV in Figure 3. As shown in Figure 4, in the region above the second predetermined vehicle speed V2, the strong regenerative torque decreases toward the medium regenerative torque, and is set to be the same as the medium regenerative torque in the vehicle speed region from the fourth predetermined vehicle speed V4 onwards. This second predetermined vehicle speed V2 is set to a vehicle speed at which, similar to the second predetermined vehicle speed V2, the strong regenerative torque is set to be larger than the medium regenerative torque by a first predetermined ratio, and at VH limit, the strong regenerative torque can no longer be output from the second motor 3. In other words, when the strong regenerative torque is set to be larger than the medium regenerative torque by a first predetermined ratio, the vehicle speed is set to match the regenerative torque obtained by subtracting the cancellation torque Tm_c from the torque that can be output at VH limit.

[0037] Furthermore, if engine 1 is stopped while traveling at a relatively high speed, the rotational speed of the first motor 2 will exceed a predetermined upper limit. Therefore, the system is configured to prohibit stopping engine 1 when traveling at a speed of 5 or higher than the 5th predetermined speed V5. In other words, there is no need to output a cancellation torque Tm_c from the second motor 3 when stopping engine 1. For this reason, the strong regenerative torque between the 2nd predetermined speed V2 and the 5th predetermined speed V5 is set to be less than or equal to the torque that can be output when VH is limited minus the cancellation torque Tm_c. Therefore, in the example shown in Figure 4, in the region of 4th vehicle speed and above, the torque obtained by adding the cancellation torque Tm_c to the strong regenerative torque is higher than the torque that can be output when VH is limited. Note that the 5th predetermined speed V5 corresponds to the "predetermined speed" in the embodiment of the present invention.

[0038] Furthermore, at vehicle speeds of V2 or higher, the strong regenerative torque should be set to a value less than or equal to the regenerative torque obtained by subtracting the cancellation torque Tm_c from the torque that can be output when VH is limited. However, if this strong regenerative torque is set to be smaller than the medium regenerative torque, the deceleration when the strong engine braking mode is set will be smaller than the deceleration when the medium engine braking mode is set, which may cause the driver to feel uncomfortable. Therefore, the strong regenerative torque in the vehicle speed range of V2 or higher is set to be greater than or equal to the medium regenerative torque.

[0039] As described above, by setting the regenerative torque in strong engine braking mode to the amount obtained by subtracting the cancellation torque Tm_c from the regenerative torque that can be output from the second motor 3 when VH is limited, it is possible to suppress situations in which the deceleration at maximum VH differs from the deceleration at VH limit. As a result, it is possible to suppress changes in the behavior of the vehicle Ve in response to the driver's accelerator input depending on whether or not factors that the driver cannot perceive occur, and thus suppress the driver from feeling any discomfort.

[0040] Furthermore, in the vehicle speed range below the fifth predetermined vehicle speed V5, where stopping the engine 1 is prohibited, the strong regenerative torque is set to be less than or equal to the torque obtained by subtracting the cancellation torque Tm_c from the torque that can be output when the VH limit is applied. In other words, in the vehicle speed range above the fifth predetermined vehicle speed V5, the strong regenerative torque is set without taking the cancellation torque Tm_c into consideration. This prevents the strong regenerative torque from being set excessively low in the vehicle speed range above the fifth predetermined vehicle speed V5, and allows for the generation of regenerative torque corresponding to the deceleration required by the driver.

[0041] Furthermore, by setting the strong regenerative torque to be less than or equal to the regenerative torque obtained by subtracting the cancellation torque Tm_c from the torque that can be output when the VH limit is applied, and greater than or equal to the medium regenerative torque, the deceleration when the strong engine braking mode is set will not be less than the deceleration when the medium engine braking mode is set, thereby suppressing any discomfort the driver may feel.

[0042] Furthermore, the differential mechanism in the embodiment of the present invention is not limited to one composed of a single differential mechanism as described above, but may also be a composite planetary gear mechanism equipped with multiple differential mechanisms. In addition, the above example shows an example in which a strong regenerative torque is set based on the torque that can be output and the cancellation torque when VH is limited, but the regenerative torque of the second motor 3 may also be limited based on, for example, the temperature of the second motor 3 or the input / output power of the energy storage device 22. Therefore, the limiting torque in the embodiment of the present invention may be a limiting torque determined by other factors instead of the torque that can be output when VH is limited. Moreover, in the above example, three deceleration modes, a strong engine braking mode, a medium engine braking mode, and a weak engine braking mode, are configured to be set, but the hybrid vehicle may be able to set at least two deceleration modes, such as a deceleration mode in which the deceleration (or regenerative torque) is relatively large and a deceleration mode in which the deceleration (or regenerative torque) is relatively small. [Explanation of Symbols]

[0043] 1 Engine 2,3 motors 5 Power split mechanism 7 Drive wheels 8 Sangiya 9.17 Ring Gear 10 Pinion Gear 11 Carrier 21 Power Control Unit (PCU) 22 Energy storage devices 23 Electronic Control Unit (ECU) 24 sensors Vehicle

Claims

1. A braking force control device for a hybrid vehicle comprising a differential mechanism in which an internal combustion engine, a first motor, and a drive wheel are differentially rotatably connected, and a second motor connected to the drive wheel or another drive wheel different from the drive wheel, The accelerator device operated by the driver, The power supply connected to the second motor, The system includes a converter that boosts the voltage of the power supply and applies it to the second motor, and a power control unit that converts the power exchanged between the power supply and the second motor. The system includes a controller that controls the regenerative torque of the second motor based on the amount of operation of the accelerator device when the amount of operation of the accelerator device is less than a predetermined amount, The aforementioned controller, The regenerative torque of the second motor is limited to at least one of two limiting torques based on the ambient pressure or the temperature of the power control unit: a predetermined first limiting torque that can be output from the second motor when the boosted voltage by the converter is limited to a predetermined first predetermined voltage due to relatively high ambient pressure or relatively low temperature of the power control unit, and a predetermined second limiting torque that is smaller than the first limiting torque that can be output from the second motor when the boosted voltage by the converter is limited to a predetermined second predetermined voltage that is smaller than the first predetermined voltage due to relatively low ambient pressure or relatively high temperature of the power control unit. The maximum regenerative torque of the second motor in the region where the amount of accelerator operation is less than the predetermined amount is set to be less than or equal to the amount obtained by subtracting a cancellation torque from the second limiting torque of the second motor, which is used to offset the torque transmitted to the drive wheels in the direction that drives the hybrid vehicle by outputting torque from the first motor and stopping the internal combustion engine. A braking force control device for a hybrid vehicle, characterized by the following features.

2. A braking force control device for a hybrid vehicle according to claim 1, The aforementioned internal combustion engine is prohibited from stopping in a range where the vehicle speed is above a predetermined speed. The aforementioned controller, The maximum regenerative torque of the second motor is set to be less than or equal to the amount obtained by subtracting the cancellation torque from the second limiting torque in the region below the predetermined vehicle speed. A braking force control device for a hybrid vehicle, characterized by the following features.

3. A braking force control device for a hybrid vehicle according to claim 1, The aforementioned controller, The system is configured to allow setting at least two deceleration modes: a strong deceleration mode in which the maximum regenerative torque of the second motor is relatively large in the region where the amount of operation of the accelerator device is less than a predetermined amount, and a weak deceleration mode in which the maximum regenerative torque is relatively small. The maximum regenerative torque in the strong deceleration mode is set to be less than or equal to the amount obtained by subtracting the cancellation torque from the second limiting torque, and greater than or equal to the maximum regenerative torque in the weak deceleration mode. A braking force control device for a hybrid vehicle, characterized by the following features.

4. A braking force control device for a hybrid vehicle according to any one of claims 1 to 3, The power control unit has a converter that boosts the voltage of the power supply and applies it to the second motor. The second limiting torque includes a regenerative torque based on a voltage that can be applied to the second motor when the boosted voltage by the converter is limited to a predetermined voltage. A braking force control device for a hybrid vehicle, characterized by the following features.

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