vehicle

Abstract

The objective is to provide vehicles that can reliably restart their internal combustion engines in a variety of situations. [Solution] The vehicle V is equipped with an internal combustion engine 3 and an electric motor 4, and has an input shaft 13, an electric motor connecting shaft 60, a switching mechanism 70, and an output shaft 15. The switching mechanism 70 switches between an input-side connection state that enables power transmission between the electric motor connecting shaft 60 and the input shaft 13, and an output-side connection state that enables power transmission between the electric motor connecting shaft 60 and the output shaft 15. When the internal combustion engine 3 is stopped and the vehicle is running solely on the power of the electric motor 4, and a restart of the internal combustion engine 3 is requested, if the conditions are met that make restarting in the output-side connection state difficult, the switching mechanism 70 switches to the input-side connection state and restarts the internal combustion engine 3 with the driving force of the electric motor 4.

Description

TECHNICAL FIELD

[0001] The present invention relates to a vehicle that includes an internal combustion engine and an electric motor, and that changes a travel mode by performing switching control of the drive sources of the internal combustion engine and the electric motor. BACKGROUND ART

[0002] Conventionally, a hybrid vehicle equipped with an electric motor (motor) and an internal combustion engine (engine) is known (for example, Patent Document 1). In such a hybrid vehicle, one or both of the electric motor and the internal combustion engine are used as drive sources. Further, the electric motor in a hybrid vehicle is configured to exhibit a function as a generator that generates electric power by regenerative torque during vehicle braking.

[0003] Some of such hybrid vehicles are provided with a mechanism capable of switching between two power transmission paths: a power transmission path that directly connects the electric motor and the crankshaft of the internal combustion engine, and a power transmission path that directly connects the electric motor and the output shaft of the vehicle. With such a configuration, a single electric motor can perform the roles of a starter motor, a generator, and a drive source. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0004] PATENT DOCUMENT 1 Japanese Unexamined Patent Application Publication No. 2010-241331 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] Incidentally, in hybrid vehicles as described above, when restarting the engine from a state where the internal combustion engine is stopped and the vehicle is running solely on the power of the electric motor, the principle is to use a power transmission path that directly connects the electric motor and the output shaft. However, this method may not be physically feasible at low speeds. Also, when the electric motor is already generating high torque, there is a possibility that insufficient surplus torque can be secured to start the internal combustion engine.

[0006] Therefore, the present invention aims to provide a vehicle that can stably restart its internal combustion engine in various situations. [Means for solving the problem]

[0007] (1) The present invention, provided to solve the above-mentioned problems, is a vehicle equipped with an internal combustion engine and an electric motor, which changes the driving mode by switching control of the drive source between the internal combustion engine and the electric motor, comprising: an input shaft that transmits power output from the internal combustion engine; an electric motor connection shaft connected to the electric motor; a switching mechanism that switches between an input-side connection state that enables power transmission between the electric motor connection shaft and the input shaft and an output-side connection state that enables power transmission between the electric motor connection shaft and the output shaft; and an output shaft that transmits power to the drive wheels of the vehicle, wherein the internal This vehicle is characterized in that, when the combustion engine is stopped and the vehicle is running solely on the driving force of the electric motor transmitted between the electric motor connecting shaft and the output shaft, and a restart of the internal combustion engine is requested, the switching control is performed by the switching mechanism to switch to a state in which power transmission between the electric motor connecting shaft and the input shaft is possible, provided that the switching conditions are met in which it is assumed that the internal combustion engine cannot be restarted based on the power transmission between the electric motor connecting shaft and the output shaft, and the internal combustion engine is restarted using the driving force of the electric motor.

[0008] According to the present invention, when a restart of the internal combustion engine is required while the motor is running, if the switching conditions are met such that the internal combustion engine cannot be restarted based on the transmission of power between the motor connecting shaft and the output shaft, the switching control is performed by the switching mechanism to switch to a state in which power transmission between the motor connecting shaft and the input shaft is possible, thereby enabling the internal combustion engine to be restarted stably in various situations. Specifically, since the motor connecting shaft and the input shaft are directly connected, the driving force of the motor can be directly transmitted to the crankshaft of the internal combustion engine, and the internal combustion engine can be restarted stably without being affected by external factors (such as vehicle speed or insufficient torque).

[0009] (2) A vehicle as described in (1) above, characterized in that the vehicle speed being below a predetermined value is part or all of the switching conditions.

[0010] According to the present invention, when the vehicle speed is below a predetermined value, the power transmission is switched to the motor connection shaft and the input shaft, making it possible to stably restart the internal combustion engine even when driving at low speeds. When driving at low speeds, the rotational speed of the output shaft also becomes low, and it may not be possible to secure the crankshaft rotational speed necessary to restart the internal combustion engine, but this problem can be solved by directly transmitting the driving force of the electric motor to the crankshaft of the internal combustion engine in the present invention.

[0011] (3) A vehicle according to (1) or (2) above, characterized in that the torque output of the electric motor is equal to or greater than a predetermined value, which is part or all of the switching conditions.

[0012] According to the present invention, when the torque output of the electric motor exceeds a predetermined value, the power transmission is switched to the connection shaft of the electric motor and the input shaft, making it possible to stably restart the internal combustion engine even when the electric motor is outputting high torque while driving. When the electric motor is already outputting high torque (for example, during acceleration or when there is high driving resistance), it is difficult to secure surplus torque to allocate to starting the internal combustion engine, but this problem can be solved by using the driving force of the electric motor to start the internal combustion engine.

[0013] (4) A vehicle according to (1) or (2) above, characterized in that, when the internal combustion engine is stopped and the vehicle is running solely on the driving force of the electric motor, the vehicle speed falls below a predetermined value, and regardless of whether or not there is a request to restart the internal combustion engine, the switching control has in advance switched to the transmission of power between the electric motor connecting shaft and the input shaft.

[0014] According to the present invention, when the vehicle speed falls below a predetermined value, the system switches to power transmission between the motor connection shaft and the input shaft, regardless of whether or not there is a request to restart the internal combustion engine. This allows for a quick restart when a restart request for the internal combustion engine occurs, thereby suppressing deterioration of drivability. In particular, during low-speed driving, there is a high probability of a restart request for the internal combustion engine occurring, so by performing the switching control in advance, a faster and more stable restart can be achieved.

[0015] (5) The vehicle described in (4) above, characterized in that, when switching in advance to power transmission between the motor connection shaft and the input shaft by the switching control, the vehicle's running state is checked and the switch is made based on at least one of the accelerator opening, brake operating state, and vehicle deceleration.

[0016] According to the present invention, when switching to power transmission between the motor connection shaft and the input shaft, the vehicle status such as accelerator opening, brake operation, and vehicle deceleration can be checked in advance before performing the switching control. This allows for improved drivability while avoiding risks such as coasting and loss of driving force. In the state where power is transmitted between the motor connection shaft and the input shaft, the driving force of the motor is not used to drive the vehicle, so it is important to perform the switching control after appropriately checking the vehicle status.

[0017] Note that the respective configurations described in the above embodiments can be implemented in appropriate combination. In particular, by determining in combination the switching conditions that the vehicle speed is less than a predetermined value and that the output torque of the electric motor is equal to or greater than a predetermined value, the power transmission path can be switched at a more appropriate timing. Further, by utilizing information from a stereo camera, map information, and the like, it is also possible to predict in advance that a driving force will be required, and to perform switching control at a more appropriate timing. Advantageous Effects of Invention

[0018] According to the present invention, a vehicle capable of stably restarting an internal combustion engine in various situations can be provided. Brief Description of Drawings

[0019] [Figure 1] This is an overall front view of a vehicle according to an embodiment of the present invention, with a cover of a transmission cut away. [Figure 2] This is a skeleton diagram of an embodiment of the transmission of FIG. 1. [Figure 3] This is a block diagram showing a configuration of a control system included in a vehicle according to an embodiment of the present invention. [Figure 4] This is a flowchart related to internal combustion engine restart control performed in a vehicle according to an embodiment of the present invention. [Figure 5] This is a flowchart related to preventive switching control performed in a vehicle according to a modified example. Mode for Carrying Out the Invention

[0020] Hereinafter, a vehicle V according to an embodiment of the present invention and a transmission 10 mounted thereon will be described in detail with reference to the drawings. It should be noted that each drawing is schematically represented for ease of understanding, and may differ from the actual shape, size, and arrangement of component parts. It should also be noted that the fact that each shaft is appropriately supported by a bearing or the like and is rotatable may be omitted. In the following description, the front side of the vehicle V may be referred to as front Fr, and the rear side as rear Rr.

[0021] «Basic Configuration of Transmission» As shown in FIG. 1 and FIG. 2, the vehicle V includes an internal combustion engine 3, an electric motor 4, and a battery 6, and changes the travel mode by performing switching control of the drive sources of the internal combustion engine 3 and the electric motor 4. The vehicle V is provided with the transmission 10. The internal combustion engine 3 and the electric motor 4 are connected to the transmission 10.

[0022] The internal combustion engine 3 is constituted by, for example, an engine such as a gasoline engine or a diesel engine. In the internal combustion engine 3, a drive shaft (not shown) is connected to an input shaft 13 of the transmission 10. Therefore, the power output by the internal combustion engine is input to the transmission 10 through the input shaft 13.

[0023] As shown in FIG. 1 and FIG. 2, the electric motor 4 is constituted by, for example, a motor generator, and can output driving force and perform power generation. In the electric motor 4, a motor shaft 4A is connected to a motor connection shaft 60 of the transmission 10 via a universal joint 5. Therefore, the power output by the electric motor 4 is input to the transmission 10 via the motor connection shaft 60.

[0024] The transmission 10 has a plurality of gears, and is configured to shift the power generated by the internal combustion engine 3 and the electric motor 4, and transmit regenerated regenerative energy to the electric motor 4.

[0025] As shown in Figures 1 and 2, the transmission 10 includes a torque converter 12, an input shaft 13, a continuously variable transmission 20 (CVT 20), a reverse transmission mechanism 40, a forward clutch 51 (clutch device 50), a reverse clutch 55 (clutch device 50), and an output shaft 15. The transmission 10 also includes an electric motor connecting shaft 60, a primary shaft 21, a secondary shaft 23, a first driven shaft 30, a second driven shaft 35, a reverse idler shaft 41, and a switching mechanism 70, etc.

[0026] As shown in Figures 1 and 2, the torque converter 12 includes a pump impeller 12A, a turbine runner 12B, and a lock-up mechanism 12C (lock-up clutch), etc. The input shaft 13 is connected to the pump impeller 12A and is able to rotate integrally with the input shaft 13 around the same axis of rotation. The turbine runner 12B is rotatable around the same axis of rotation as the pump impeller 12A.

[0027] The lock-up mechanism 12C is provided to directly connect / disconnect the pump impeller 12A and the turbine runner 12B. When the lock-up mechanism 12C is engaged (lock-up on), the pump impeller 12A and the turbine runner 12B are directly connected, and when the lock-up mechanism 12C is released (lock-up off), the pump impeller 12A and the turbine runner 12B are separated.

[0028] The input shaft 13 is positioned so that its axis coincides with the rotation axis of the torque converter 12. The input shaft 13 can transmit power output from the internal combustion engine 3. An input shaft gear 14 is integrally formed on the input shaft 13. The front end Fr of the input shaft 13 is inserted into the torque converter 12.

[0029] The output shaft 15 is positioned at a rearward (Rr) distance from the input shaft 13. The output shaft 15 is positioned so that its axis aligns with the axis of the input shaft 13. Although not shown in the illustration, the output shaft 15 can transmit power to the drive wheels of the vehicle V via a drive shaft or the like. An output shaft gear 16 is integrally formed on the output shaft 15.

[0030] The continuously variable transmission 20 is provided with a primary shaft 21, a secondary shaft 23, a primary pulley 26, a secondary pulley 27, and a belt 28. A primary input gear 22 (also called a driven gear 22) is mounted on the primary shaft 21 so as to be rotatable relative to it. The primary input gear 22 meshes with an input shaft gear 14 and a second driven gear 36, which will be described later.

[0031] A secondary input gear 24 and a secondary output gear 25 are mounted on the secondary shaft 23. The secondary input gear 24 is rotatable relative to the secondary shaft 23. The secondary output gear 25 is mounted so as not to rotate relative to the secondary shaft 23. The secondary output gear 25 meshes with an output shaft gear 16 provided on the output shaft 15.

[0032] In the continuously variable transmission 20, a belt 28 is stretched between a primary pulley 26 and a secondary pulley 27. In the continuously variable transmission 20, the hydraulic pressure supplied to the hydraulic chambers (not shown) of the primary pulley 26 and the secondary pulley 27 is controlled, and the groove widths of the primary pulley 26 and the secondary pulley 27 are changed, thereby continuously changing the belt gear ratio (pulley ratio between the primary pulley 26 and the secondary pulley 27) within a constant gear ratio range. The rotational force (power) of the shifted secondary shaft 23 is transmitted to the output shaft 15 via the secondary output gear 25 and the output shaft gear 16, driving the drive wheels (not shown).

[0033] The reverse transmission mechanism 40 is a mechanism that transmits power (rotation) from the input shaft 13 to the secondary input gear 24. The reverse transmission mechanism 40 is equipped with a reverse idler shaft 41 and reverse idler gears 42 (first reverse idler gear 42A and second reverse idler gear 42B).

[0034] The reverse idler shaft 41 is a shaft located midway between the secondary shaft 23 and the first driven shaft 30, which will be described later. As shown in Figure 1, the reverse idler shaft 41 is rotatably supported at both ends by a front bearing 44 and a rear bearing 46. The front bearing 44 and the rear bearing 46 are each held in the transmission case 10A. The front bearing 44 is located at the end of the reverse idler shaft 41 on the side of the first reverse idler gear 42A. The rear bearing 46 is located at the end on the side of the second reverse idler gear 42B.

[0035] As shown in Figures 1 and 2, the first reverse idler gear 42A is integrally formed with the reverse idler shaft 41 and meshes with the input shaft gear 14. In other words, the first reverse idler gear 42A can reverse the rotation direction of the input shaft gear 14 (input shaft 13).

[0036] The second reverse idler gear 42B is formed integrally with the reverse idler shaft 41 at the rear Rr of the first reverse idler gear 42A and meshes with the secondary input gear 24.

[0037] The forward clutch 51 (clutch device 50) is provided to allow / prevent the rotation of the primary input gear 22 relative to the primary shaft 21. The forward clutch 51 forms a clutch device 50 that includes a clutch drum, clutch piston, friction material, and hydraulic chamber, although these are not shown in the figures. The forward clutch 51 controls the engagement of the clutch by controlling the supply of oil to the hydraulic chamber according to the output value of a solenoid (not shown).

[0038] When the forward clutch 51 is engaged (engaged state), relative rotation of the primary input gear 22 with respect to the primary shaft 21 is prohibited. In other words, the engagement of the forward clutch 51 causes the primary shaft 21 and the primary input gear 22 to rotate as a single unit. As a result, a driving force in the forward direction is transmitted to the output shaft 15 via the continuously variable transmission 20, and the drive wheels (not shown) are driven in the forward direction.

[0039] The reverse clutch 55 (clutch device 50) is provided to allow / prevent the rotation of the secondary input gear 24 relative to the secondary shaft 23. The reverse clutch 55 has the same configuration as the forward clutch 51.

[0040] When the reverse clutch 55 is engaged (engaged state), relative rotation of the secondary input gear 24 with respect to the secondary shaft 23 is prohibited. In other words, the engagement of the reverse clutch 55 causes the secondary shaft 23 and the secondary input gear 24 to rotate together. This transmits a driving force in the reverse direction to the output shaft 15, and drives the drive wheels (not shown) in the reverse direction. On the other hand, when the reverse clutch 55 is released (released state), relative rotation of the secondary input gear 24 with respect to the secondary shaft 23 is permitted. Therefore, even if the secondary input gear 24 rotates, that rotation is not transmitted to the secondary shaft 23.

[0041] The motor connecting shaft 60 has a first motor connecting shaft 60A and a second motor connecting shaft 60B (hereinafter, the first motor connecting shaft 60A may be referred to as the front end side (Fr side) of the motor connecting shaft 60, and the second motor connecting shaft 60B may be referred to as the rear end side (Rr side) of the motor connecting shaft 60). As shown in Figures 1 and 2, a universal joint 5 is connected to the front end (front Fr side / first motor connecting shaft 60A) of the motor connecting shaft 60. The motor shaft 4A of the electric motor 4 (for example, a motor generator) is connected to the front end side (Fr side) of the universal joint 5. A motor connecting shaft gear 61, an output side gear 33, a switching mechanism 70, and the second motor connecting shaft 60B are provided on the axis of the motor connecting shaft 60.

[0042] The motor connecting shaft gear 61 is located on the first motor connecting shaft 60A, which is on the front end (front Fr side) of the motor connecting shaft 60. The motor connecting shaft gear 61 has an outer sleeve shape and is connected to a clutch 71 which is part of the switching mechanism 70. The motor connecting shaft gear 61 is designed so that the motor connecting shaft 60 and the motor connecting shaft gear 61 can rotate synchronously when the switching mechanism 70 is in a state that enables power transmission between the motor connecting shaft 60 and the input shaft 13 (input side connection state), as will be described in detail later. The motor connecting shaft gear 61 meshes with the third driven gear 32A on the first driven shaft 30. Therefore, when the motor 4 is driven, the power output from the motor 4 is transmitted to the first driven shaft 30. As will be described in more detail later, when the first driven shaft 30 is driven by the internal combustion engine 3, the power output from the internal combustion engine 3 is transmitted to the first driven shaft 30 and then used to generate electricity for the electric motor 4 via the motor connecting shaft gear 61 and the motor connecting shaft 60.

[0043] As shown in Figures 2 and 4, the first driven shaft 30 is provided between the motor connection shaft 60 and the input shaft 13. The first driven shaft 30 is rotatably supported at both its front end (front Fr side) and rear end (rear Rr side). A first driven gear 32 is also fixed to the middle of the first driven shaft 30.

[0044] The first driven gear 32 comprises a third driven gear 32A and a fourth driven gear 32B positioned on the rear side (Rr) of the third driven gear 32A.

[0045] The third driven gear 32A meshes with the motor connection shaft gear 61. Therefore, the first driven shaft 30 can transmit the power output from the motor connection shaft 60.

[0046] The fourth driven gear 32B is located on the opposite side of the first driven shaft 30 from the internal combustion engine 3 side (towards the transmission 10 side) in the axial direction of the first driven shaft 30. The fourth driven gear 32B meshes with the second driven gear 36, which is fixed to the second driven shaft 35, which will be described later.

[0047] As shown in Figures 1 and 2, the second driven shaft 35 is positioned parallel to the first driven shaft 30, with a gap between them. The second driven gear 36 is mounted to the second driven shaft 35.

[0048] The second driven gear 36 meshes with the primary input gear 22 (driven gear 22) and the fourth driven gear 32B. Therefore, when the clutch 71 of the switching mechanism 70 is in the "input side engaged state", the second driven gear 36 can rotate together with the second driven shaft 35 in accordance with the rotation of the primary input gear 22. That is, the power output from the internal combustion engine 3 is transmitted to the motor connection shaft 60 via the primary input gear 22, the second driven shaft 35, and the first driven shaft 30, and is used for generating electricity in the motor 4. Also, the second driven gear 36 can rotate together with the second driven shaft 35 in accordance with the rotation of the first driven shaft 30. That is, the power output from the motor 4 is transmitted to the first driven shaft 30, the second driven shaft 35, and the input shaft 13, and is used for starting the internal combustion engine 3.

[0049] The output gear 33 is fixed to the second motor connecting shaft 60B. The output gear 33 meshes with the output transmission shaft gear 18 (also called the output idler gear 18), which is fixed to the output transmission shaft 17 (described later). (Note that although the diagram shows the output gear 33 and the output transmission shaft 17 as being separated, they are actually meshed with each other.)

[0050] The output transmission shaft 17 is mounted parallel to the motor connection shaft 60, with a gap between them. An output transmission shaft gear 18 is mounted on the output transmission shaft 17. The output transmission shaft gear 18 meshes with the output shaft gear 16 on the output shaft 15. The output transmission shaft gear 18 also meshes with the output side gear 33 on the first driven shaft 30. The output transmission shaft gear 18 also meshes with the output shaft gear 16 on the output shaft 15. Therefore, the output transmission shaft 17 can transmit power from the first driven shaft 30 to the output shaft 15 as the first driven shaft 30 rotates.

[0051] The switching mechanism 70 is located between the first motor connecting shaft 60A and the second motor connecting shaft 60B. The switching mechanism 70 includes a clutch 71 and the like.

[0052] The switching mechanism 70 can switch between an "input-side connection state" that enables power transmission between the motor connection shaft 60 and the input shaft 13, and an "output-side connection state" that enables power transmission between the motor connection shaft 60 and the output shaft 15, by switching the connection state of the clutch 71 by hydraulics or the like. Specifically, the motor connection shaft 60 is divided into a first motor connection shaft 60A and a second motor connection shaft 60B via the clutch 71 of the switching mechanism 70. The first motor connection shaft 60A is equipped with a motor connection shaft gear 61, and the second motor connection shaft 60B is equipped with an output-side gear 33.

[0053] Therefore, in the "input-side connected state," the second motor connecting shaft 60B is not connected (the rear Rr side of the clutch 71 is not engaged), and only the first motor connecting shaft 60A rotates. That is, the motor connecting shaft gear 61 (input-side gear 61) rotates in conjunction with the rotation of the first motor connecting shaft 60A. Therefore, when the internal combustion engine 3 is driven in the "input-side connected state," the power output from the internal combustion engine 3 is used to generate electricity for the motor 4 via the input shaft 13, primary shaft 21, second driven shaft 35, first driven shaft 30, and motor connecting shaft 60. On the other hand, when the internal combustion engine 3 is stopped in the "input-side connected state," the power output from the motor 4 is used to start the internal combustion engine 3 via the motor connecting shaft 60, first driven shaft 30, second driven shaft 35, primary shaft 21, and input shaft 13.

[0054] Furthermore, in the "output-side connected state," the clutch 71 engages, connecting the second motor connecting shaft 60B, causing the first motor connecting shaft 60A and the second motor connecting shaft 60B to rotate together. Therefore, when the motor 4 is driven in the "output-side connected state," the power output from the motor 4 is used to drive the drive wheels (not shown) via the first motor connecting shaft 60A and the second motor connecting shaft 60B (EV driving state or assisted driving (HEV driving) state). On the other hand, when the drive wheels are braked (decelerated) in the "output-side connected state," the braking force acting on the output shaft 15 is used for regeneration (power generation) of the motor 4 via the motor connecting shaft 60.

[0055] <<Overview of the control system>> The control system of vehicle V will now be described. In addition to the transmission 10 described above, vehicle V is equipped with a control device 100 for controlling the vehicle. The control device 100 controls the powertrain, which includes the internal combustion engine 3, the electric motor 4, and the transmission 10. The control device 100 is connected to a group of sensors that detect various operating states, such as a vehicle speed sensor 102 for detecting vehicle speed, a torque sensor 104 for detecting the torque output of the electric motor 4, an accelerator opening sensor 106 for detecting the accelerator opening, and a brake sensor 108 for detecting the brake operation state.

[0056] The control device 100 performs control to restart the internal combustion engine 3 from a state where the vehicle is running solely on the driving force of the electric motor 4 while the internal combustion engine 3 is stopped. In this restart control, the control device selects, depending on the situation, between normal control, which restarts the internal combustion engine 3 using the driving force of the electric motor 4 by transmitting power between the electric motor connecting shaft 60 and the output shaft 15, and switching control, which restarts the internal combustion engine 3 by switching to power transmission between the electric motor connecting shaft 60 and the input shaft 13.

[0057] This selection is made based on switching conditions that are assumed to prevent the restart of the internal combustion engine 3. These switching conditions include, for example, the vehicle speed being below a predetermined value or the torque output of the electric motor 4 being above a predetermined value. This allows for stable restarting of the internal combustion engine 3 even during low-speed driving or when sufficient surplus torque from the electric motor 4 cannot be secured.

[0058] Control during internal combustion engine restart The restart control of the internal combustion engine 3 will now be described. The vehicle V has a function to restart the internal combustion engine 3 from EV driving mode, in which the vehicle is running solely on the driving force of the electric motor 4 after the internal combustion engine 3 has been stopped. This restart is performed based on, for example, an increase in the acceleration request, a decrease in the battery charge 6, or a request for power generation by the internal combustion engine 3.

[0059] A basic method for restarting the internal combustion engine 3 is to use the power transmission (power transmission path 2) between the motor connecting shaft 60 and the output shaft 15. Specifically, in the "output-side connection state" where the motor connecting shaft 60 and the output shaft 15 are directly connected, the forward clutch 51 and the lock-up clutch 12C are engaged to transmit the driving force of the electric motor 4 to the crankshaft via the output shaft 15, thereby starting the internal combustion engine 3.

[0060] In this method, a single electric motor 4 can be used for both driving the vehicle and starting the internal combustion engine 3. A portion of the torque that the electric motor 4 uses for driving is allocated to starting the internal combustion engine 3. As a result, it is possible to restart the internal combustion engine 3 while the vehicle is in motion without causing a loss of driving force.

[0061] ≪Determination of switching conditions≫ However, the basic restarting methods described above cannot always be implemented. For example, at low vehicle speeds, the rotational speed of the output shaft 15 will also be low, and it may not be possible to secure the crankshaft rotational speed necessary to restart the internal combustion engine 3. Also, if the electric motor 4 is already generating high torque while driving, it may not be possible to secure enough surplus torque to be distributed to start the internal combustion engine 3.

[0062] Therefore, in this embodiment, a switching condition is set in which it is assumed that the internal combustion engine 3 cannot be restarted, and control is performed to switch the restart method based on this condition. Specific switching conditions include the following:

[0063] The first switching condition is that the vehicle speed is below a predetermined value. When the vehicle speed is low, the rotational speed of the primary shaft 21 of the CVT 20 also decreases, and the rotational speed transmitted to the crankshaft is likely to fall below the rotational speed required to start the internal combustion engine 3. Therefore, if the vehicle speed is below a predetermined value (for example, the vehicle speed during low-speed driving), it is determined that restarting via the power transmission path 2 cannot be performed.

[0064] The second switching condition is that the torque output of the electric motor 4 is above a predetermined value. When the electric motor 4 is already outputting high torque (for example, during acceleration or on an uphill road or uneven terrain where driving resistance is high), it is difficult to secure surplus torque to be distributed for starting the internal combustion engine 3. Therefore, if the torque output of the electric motor 4 is above a predetermined value, it is determined that restarting via the power transmission path 2 cannot be performed.

[0065] ≪Power transmission path switching control during restart≫ If the above-described switching conditions are met, in this embodiment, the switching mechanism 70 is controlled to switch to a state in which power transmission between the motor connection shaft 60 and the input shaft 13 is possible (input side connection state). In this state, the motor connection shaft 60 and the input shaft 13 are directly connected, so the driving force of the electric motor 4 can be directly transmitted to the crankshaft of the internal combustion engine 3.

[0066] Specifically, the clutch 71 of the switching mechanism 70 is controlled to release the connection between the front Fr side and the rear Rr side of the motor connection shaft 60, resulting in an "input side connection state" where only the front Fr side of the motor connection shaft 60 rotates. In this state, the power output from the motor 4 is transmitted to the crankshaft of the internal combustion engine 3 via the motor connection shaft 60, the first driven shaft 30, the second driven shaft 35, the primary shaft 21, and the input shaft 13.

[0067] Restarting the internal combustion engine 3 using this input connection method has the advantage of being able to be performed stably without being affected by external factors (such as vehicle speed or insufficient torque). However, in this method, the driving force of the electric motor 4 is not used to drive the vehicle but is used to start the internal combustion engine 3, so the vehicle's driving force will be temporarily lost.

[0068] Control Flow Figure 4 shows a flowchart of the internal combustion engine restart control in this embodiment. When performing internal combustion engine restart control, the internal combustion engine 3 is first stopped, and it is determined whether there is a request to restart the internal combustion engine 3 while the vehicle is traveling using only the driving force of the electric motor 4 (Step 1-1). If there is no restart request, the current driving state is maintained.

[0069] If a restart request is made, it is determined whether the switching conditions are met (Step 1-2). Specifically, it is determined whether the vehicle speed is below a predetermined value or whether the torque output of the electric motor 4 is above a predetermined value. If either of these conditions is met, it is determined that restarting via the power transmission path 2 cannot be performed.

[0070] If the switching conditions are met, the switching mechanism 70 is controlled to switch to an input-side connection state that allows power transmission between the motor connection shaft 60 and the input shaft 13 (step 1-3), and the internal combustion engine 3 is restarted by the driving force of the electric motor 4 (step 1-4).

[0071] On the other hand, if the switching conditions are not met, it is determined that restarting is possible via the power transmission path 2, and the internal combustion engine 3 is restarted using a portion of the driving force of the electric motor 4 while maintaining the current output side connection state (steps 1-5).

[0072] Thus, in this embodiment, by appropriately switching the restart method based on the switching conditions under which it is assumed that the internal combustion engine 3 cannot be restarted, it becomes possible to stably restart the internal combustion engine 3 even when driving at low speeds or when there is insufficient surplus torque from the electric motor 4.

[0073] ≪Variations≫ In the above embodiment, control was described in which the switching conditions are determined and the power transmission path is switched when a restart request for the internal combustion engine 3 is received. However, the present invention is not limited thereto. Modifications are described below.

[0074] As a first variation, a control system that proactively switches the power transmission path can be considered. Specifically, when the internal combustion engine 3 is stopped and the vehicle is driving, if the vehicle speed falls below a certain value, a control system may be introduced that switches the power transmission path to the input side connected state (power transmission path 1) by switching the clutch 71, which is configured with a dog clutch, in advance, regardless of whether there is a request to restart the internal combustion engine 3.

[0075] When this preventative switching control is implemented, neither the internal combustion engine 3 nor the electric motor 4 will transmit power to the wheels, creating a risk of coasting or loss of traction. Therefore, it is desirable to implement this control only after confirming safety using information such as accelerator opening, brake switch status, vehicle deceleration, brake control operation status, and distance to the vehicle in front.

[0076] By introducing this type of preventative switching control, it becomes possible to quickly restart the internal combustion engine 3 when a restart request occurs, thereby suppressing the deterioration of drivability.

[0077] Figure 5 shows the flowchart of the preventative switching control described above. Once it is confirmed that the vehicle is running solely on the driving force of the electric motor 4 (step 2-1), it is determined whether the vehicle speed has fallen below a predetermined value (step 2-2). If the vehicle speed has not fallen below the predetermined value, the vehicle continues to run as is. On the other hand, if the vehicle speed has fallen below the predetermined value, it is determined whether conditions such as accelerator opening and brake status (precautionary switching conditions) are satisfied as a safety check (step 2-3). If the precautionary switching conditions are not satisfied, the vehicle continues to run as is without performing preventative switching. However, if it is determined that the precautionary switching conditions are satisfied, the vehicle switches to the input side connection state in advance, regardless of whether or not there is a request to restart the internal combustion engine 3 (step 2-4). This allows the vehicle to restart the internal combustion engine 3 quickly when a restart request occurs, thereby improving drivability.

[0078] As a second modification, a modification of the method for determining the excess torque of the electric motor 4 can be considered. In the above embodiment, the determination was made by whether the current torque output of the electric motor 4 was above a predetermined value, but it is also possible to predict in advance when driving force will be needed using information from a stereo camera or map information, and to implement control to switch the power transmission path at an appropriate timing.

[0079] For example, if a steep slope is detected ahead using camera or map information, the system can predict that the torque of the electric motor 4 will increase before reaching the slope and switch to the input-side connection state in advance. This allows for switching the power transmission path at a more appropriate timing, further improving drivability.

[0080] Furthermore, in the above embodiment, the switching of the power transmission path was determined based on two conditions: vehicle speed and motor torque. However, a combined determination combining these conditions may also be performed. For example, even if the vehicle speed is below a predetermined value, if the torque output by the electric motor 4 is sufficiently small, it may be determined that restarting via the power transmission path 2 is possible.

[0081] Furthermore, although a continuously variable transmission (CVT) was used as an example of the transmission 10 in this embodiment, the present invention is not limited to this and can also be applied to other types of transmissions such as stepped transmissions and dual-clutch transmissions (DCTs).

[0082] <Effects> The vehicle V described above has the following characteristic configurations (a) to (e). Therefore, the vehicle V of this embodiment can achieve the following unique effects that cannot be achieved with the prior art.

[0083] (a) The vehicle V of this embodiment is equipped with an internal combustion engine 3 and an electric motor 4, and is a vehicle V that changes the driving mode by switching control of the drive source between the internal combustion engine 3 and the electric motor 4, and is equipped with an input shaft 13 that transmits power output from the internal combustion engine 3, an electric motor connection shaft 60 connected to the electric motor 4, a switching mechanism 70 that switches between an input-side connection state that enables power transmission between the electric motor connection shaft 60 and the input shaft 13 and an output-side connection state that enables power transmission between the electric motor connection shaft 60 and the output shaft 15, and an output shaft 15 that transmits power to the drive wheels of the vehicle V, and the internal combustion engine When the internal combustion engine 3 is requested to be restarted from a state where the motor 3 is stopped and the vehicle is running solely on the driving force of the motor 4 through power transmission between the motor connecting shaft 60 and the output shaft 15, the switching control is performed by the switching mechanism 70 to switch to a state where power transmission between the motor connecting shaft 60 and the input shaft 13 is possible, provided that the switching conditions are met in which it is assumed that the internal combustion engine 3 cannot be restarted based on power transmission between the motor connecting shaft 60 and the output shaft 15, and the internal combustion engine 3 is restarted using the driving force of the motor 4.

[0084] In this embodiment, as described in (a) above, when a restart of the internal combustion engine 3 is requested while the vehicle V is running on the electric motor, if the switching conditions are met in which it is assumed that the internal combustion engine 3 cannot be restarted based on the transmission of power between the electric motor connecting shaft 60 and the output shaft 15, the switching control is performed by the switching mechanism 70 to switch to a state in which power transmission between the electric motor connecting shaft 60 and the input shaft 13 is possible, thereby enabling the internal combustion engine 3 to be restarted stably in various situations. Specifically, since the electric motor connecting shaft 60 and the input shaft 13 are directly connected, the driving force of the electric motor 4 can be directly transmitted to the crankshaft of the internal combustion engine 3, and the internal combustion engine 3 can be restarted stably without being affected by external factors (such as vehicle speed or insufficient torque).

[0085] (b) The vehicle V of this embodiment is characterized in that the vehicle speed being below a predetermined value is part or all of the switching condition.

[0086] In this embodiment, as described in (b) above, when the vehicle speed is below a predetermined value, the vehicle V switches to power transmission between the motor connecting shaft 60 and the input shaft 13, thereby enabling stable restarting of the internal combustion engine 3 even during low-speed driving. During low-speed driving, the rotational speed of the output shaft 15 also decreases, and it may not be possible to secure the crankshaft rotational speed necessary to restart the internal combustion engine 3. However, in this embodiment, this problem can be solved by directly transmitting the driving force of the electric motor 4 to the crankshaft of the internal combustion engine 3.

[0087] Although the vehicle V in this embodiment is equipped with the configuration described in (b) above, the present invention is not limited thereto. The vehicle V may also be equipped without the configuration described in (b) above. For example, the switching condition may be determined based on conditions other than vehicle speed (for example, only the torque output of the electric motor 4). It is also possible to determine the switching condition based on other parameters that correlate with vehicle speed, such as the rotational speed of the primary shaft 21 of the CVT 20.

[0088] (c) The vehicle V of this embodiment is characterized in that the torque output of the electric motor 4 being equal to or greater than a predetermined value is part or all of the switching condition.

[0089] In this embodiment, as described in (c) above, when the torque output of the electric motor 4 exceeds a predetermined value, the vehicle V switches to power transmission between the electric motor connecting shaft 60 and the input shaft 13, thereby enabling stable restarting of the internal combustion engine 3 even when the electric motor 4 is running with high torque. When the electric motor 4 is already outputting high torque (for example, during acceleration or when there is high driving resistance), it is difficult to secure surplus torque to allocate to starting the internal combustion engine 3, but in this embodiment, this problem can be solved by using the driving force of the electric motor 4 to start the internal combustion engine 3.

[0090] Although the vehicle V in this embodiment is equipped with the configuration described in (c) above, the present invention is not limited thereto. The vehicle V may also be equipped without the configuration described in (c) above. For example, the switching condition may be determined based on conditions other than the torque output of the electric motor 4 (e.g., only the vehicle speed). It is also possible to determine the switching condition based on other parameters that correlate with the load state of the electric motor 4, such as the heat generation state of the electric motor 4 or the estimated value of the running resistance.

[0091] (d) The vehicle V of this embodiment is characterized in that, when the internal combustion engine 3 is stopped and the vehicle is running solely on the driving force of the electric motor 4, the vehicle speed falls below a predetermined value, and regardless of whether or not there is a request to restart the internal combustion engine 3, the power transmission is switched in advance by switching control to the transmission between the electric motor connecting shaft 60 and the input shaft 13.

[0092] In this embodiment, as described in (d) above, when the vehicle speed falls below a predetermined value, the vehicle V switches in advance to power transmission between the motor connecting shaft 60 and the input shaft 13, regardless of whether or not there is a request to restart the internal combustion engine 3. This makes it possible to quickly restart the internal combustion engine 3 when a restart request occurs, thereby suppressing deterioration of drivability. In particular, when driving at low speeds, there is a high possibility that a restart request for the internal combustion engine 3 will occur, so by performing the switching control in advance, a faster and more stable restart can be achieved.

[0093] Although the vehicle V in this embodiment is equipped with the configuration described in (d) above, the present invention is not limited thereto. The vehicle V may also be configured not to be equipped with the configuration described in (d) above. For example, the configuration may be such that switching control is performed only when a restart request is made for the internal combustion engine 3. This reduces unnecessary switching control and minimizes the impact on drivability. It is also possible to perform preventive switching control based on other conditions that predict the occurrence of a restart request (for example, a tendency for the battery charge level of 6 to decrease).

[0094] (e) The vehicle V of this embodiment is characterized in that, when switching in advance to transmit power between the motor connection shaft 60 and the input shaft 13 by switching control, the vehicle V checks the running state of the vehicle V based on at least one of the accelerator opening, the brake operating state, and the deceleration of the vehicle V before switching.

[0095] In this embodiment, as described in (e) above, when switching to power transmission between the motor connecting shaft 60 and the input shaft 13, the vehicle V can improve drivability while avoiding risks such as coasting and loss of driving force by checking the vehicle status such as accelerator opening, brake operation status, and vehicle deceleration of the vehicle V before performing the switching control. In the state where power is transmitted between the motor connecting shaft 60 and the input shaft 13, the driving force of the motor 4 is not used to drive the vehicle, so it is important to perform the switching control after appropriately checking the vehicle status.

[0096] Although the vehicle V in this embodiment is equipped with the configuration described in (e) above, the present invention is not limited thereto. The vehicle V may also be equipped with a configuration that does not include the configuration described in (e) above. For example, it is possible to configure the vehicle to perform switching control based only on vehicle speed. This makes it possible to simplify the control. It is also possible to check the vehicle status based on other vehicle status parameters, such as the distance to the vehicle in front or information from a stereo camera.

[0097] The present invention is not limited to the configurations described in the embodiments, etc. above, and can be modified as appropriate without departing from the scope of the technical idea of ​​the present invention. The components of each embodiment and modification described above can be arbitrarily selected and combined. Furthermore, any component of each embodiment and modification can be arbitrarily combined with any component described in the means for solving the problem, the form for carrying out the invention, etc., or a component that embodies any component described in the means for solving the problem, the form for carrying out the invention, etc. The present application also intends to obtain rights in this application or in divisional applications, amendment applications, etc. based on this application. [Industrial applicability]

[0098] The present invention can be suitably used in all types of vehicles that include an internal combustion engine, an electric motor, and a battery, and that change the driving mode by switching and controlling the drive source between the internal combustion engine and the electric motor. [Explanation of Symbols]

[0099] 3: Internal combustion engine 4: Electric motor 6: Battery 13: Input axis 15: Output axis 21: Primary axis 60: Motor connecting shaft 70: Switching mechanism V: Vehicle

Claims

1. A control method for a vehicle equipped with an internal combustion engine, an electric motor, and a battery, which changes the driving mode by switching and controlling the drive source between the internal combustion engine and the electric motor, The aforementioned vehicle is An input shaft that transmits power output from the internal combustion engine, The motor connection shaft connected to the aforementioned motor, A switching mechanism that switches between an input-side connection state that enables power transmission between the motor connection shaft and the input shaft and an output-side connection state that enables power transmission between the motor connection shaft and the output shaft, An output shaft that transmits power to the drive wheels of the aforementioned vehicle, Equipped with, When the internal combustion engine has been stopped and the vehicle is running solely on the driving force of the electric motor transmitted between the motor connecting shaft and the output shaft, and a restart of the internal combustion engine is requested, A vehicle characterized by performing switching control to switch the switching mechanism to a state in which power transmission between the motor connecting shaft and the input shaft is possible, provided that switching conditions are satisfied in which it is assumed that the internal combustion engine cannot be restarted based on the transmission of power between the motor connecting shaft and the output shaft, and restarting the internal combustion engine with the driving force of the electric motor.

2. The vehicle according to claim 1, characterized in that the vehicle speed being below a predetermined value is part or all of the switching conditions.

3. The vehicle according to claim 1 or 2, characterized in that the torque output of the electric motor is greater than or equal to a predetermined value, which is part or all of the switching conditions.

4. The vehicle according to claim 1 or 2, characterized in that, while the internal combustion engine is stopped and the vehicle is running solely on the driving force of the electric motor, the vehicle speed falls below a predetermined value, and regardless of whether or not there is a request to restart the internal combustion engine, the switching control has been pre-configured to transmit power between the electric motor connecting shaft and the input shaft.

5. The vehicle according to claim 4, characterized in that, when switching in advance to power transmission between the motor connection shaft and the input shaft by the switching control, the vehicle's running state is checked and the switch is made based on at least one of the accelerator opening, brake operating state, and vehicle deceleration.

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