vehicle

Abstract

The objective was to provide a vehicle that can improve fuel efficiency by reducing mechanical losses caused by the motor's rotation when regeneration occurs under high battery charge conditions. [Solution] Vehicle V is equipped with an internal combustion engine 3, an electric motor 4, and a battery 6, and controls the switching of the drive sources of the internal combustion engine 3 and the electric motor 4. The transmission 10 of vehicle V is equipped with an input shaft 13 that transmits power from the internal combustion engine 3, an electric motor connection shaft 60 connected to the electric motor 4, an output shaft 15 that transmits power to the drive wheels of vehicle V, and a switching mechanism 70 that switches the power transmission state between the electric motor connection shaft 60 and the input shaft 13 and the output shaft 15. Vehicle V is equipped with a detection unit that detects the driving state and a control unit that controls the switching mechanism 70, and when the charge level of the battery 6 is high and the electric motor 4 is in a regenerative state due to power transmission from the drive wheels, the electric motor connection shaft 60 is controlled to an intermediate state that disconnects it from the input shaft 13 and the output shaft 15.

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, hybrid vehicles equipped with an electric motor (motor) and an internal combustion engine (engine) are known. In such hybrid vehicles, 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] Patent Document 1 discloses a vehicle equipped with a drive unit of a parallel hybrid mechanism in which one or both of a motor (MG) and an engine are used as drive sources. It is known that such a vehicle travels by switching the drive source and the power transmission path in accordance with the SOC (state of charge) of a battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] By the way, in a situation where the state of charge (SOC) of the battery is high, when regenerative charging is performed in the electric motor (MG) by transmission of drive force from drive wheels or transmission of power from the internal combustion engine during the hybrid travel mode or the engine travel mode, there is a problem that mechanical loss due to idling rotation of the electric motor occurs even in a situation where charging by the electric motor is unnecessary, leading to deterioration of fuel efficiency.

[0006] Therefore, the present invention aims to provide a vehicle that can improve fuel efficiency by reducing mechanical losses caused by the rotation of the electric motor when the battery is charged at a high charge level. [Means for solving the problem]

[0007] The vehicle of the present invention, provided to solve the above-mentioned problems, has the following configuration.

[0008] (1) The vehicle of the present invention is equipped with an internal combustion engine, an electric motor, and a battery, and is a vehicle that changes the driving mode by switching control of the drive source between the internal combustion engine and the electric motor, the vehicle has a transmission, the transmission has an input shaft that transmits power output from the internal combustion engine, an electric motor connection shaft connected to the electric motor, a switching shaft that transmits power between the input shaft and the electric motor connection shaft, an output shaft that transmits power to the drive wheels of the vehicle, and an input side connection state that enables the transmission of the power between the electric motor connection shaft and the input shaft, the electric motor connection shaft and the output The device comprises a switching mechanism that switches between an output-side connection state that enables the transmission of power between the shafts, a detection unit that detects the running state of the vehicle, and a control unit that controls the operation of the switching mechanism, wherein the switching mechanism is controlled to be in an intermediate state in which the motor connection shaft is disconnected from both the input shaft and the output shaft, provided that the battery charge level is in a high-state-of-charge (SOC) state, which is higher than a predetermined reference charge level, and the motor is in a state of regeneration due to the transmission of driving force from the drive wheels or the power transmission from the internal combustion engine.

[0009] As described in (1) above, the vehicle of the present invention controls the switching mechanism to an intermediate state in which the motor connection shaft is disconnected from both the input shaft and the output shaft when the vehicle is in a high SOC state and in a regenerative state. As a result, the motor is completely disconnected from the power transmission path, eliminating mechanical losses caused by the motor's rotation and improving fuel efficiency. In addition, by stopping the charging of the motor in the high SOC state where charging is not required, battery overcharging can be prevented.

[0010] (2) The vehicle of the present invention described above comprises a switching mechanism which includes a first switching mechanism which transmits and releases power between the motor connection shaft and the input shaft, and a second switching mechanism which transmits and releases power between the motor connection shaft and the output shaft, and the control unit which, under the conditions that the battery charge level is in the high SOC state and the motor is regenerating power through the transmission of driving force from the drive wheels or the power transmission from the internal combustion engine, releases both the first switching mechanism and the second switching mechanism to bring the vehicle to the intermediate state.

[0011] As described in (2) above, the vehicle of the present invention achieves an intermediate state by releasing both the first and second switching mechanisms. This ensures that the motor connection shaft is reliably disconnected from both the input and output shafts, effectively preventing mechanical losses due to the motor's rotation. Furthermore, by appropriately adjusting the engagement state of the first and second switching mechanisms, it becomes possible to flexibly switch the power transmission path according to the vehicle's driving conditions.

[0012] (3) The vehicle of the present invention described above is characterized in that the control unit controls the switching mechanism to enter the intermediate state, provided that the running efficiency of the internal combustion engine alone is higher than the running efficiency of the internal combustion engine and the electric motor combined.

[0013] As described in (3) above, the vehicle of the present invention compares the driving efficiency of the internal combustion engine alone with the driving efficiency of the internal combustion engine and electric motor, and sets an intermediate state when the driving efficiency of the internal combustion engine alone is higher. This makes it possible to always select the most efficient driving mode, thereby maximizing the fuel efficiency of the vehicle as a whole. Furthermore, in areas where the electric motor does not operate efficiently (for example, in high-speed areas), the electric motor can be completely disconnected to obtain an even greater fuel efficiency improvement.

[0014] (4) The vehicle of the present invention described above may be characterized in that the control unit controls the switching mechanism to enter the intermediate state, provided that the deceleration force acting on the drive wheels exceeds a predetermined value when the battery charge level is in the high SOC state.

[0015] As described in (4) above, the vehicle of the present invention enters an intermediate state when the deceleration force acting on the drive wheels in a high SOC state exceeds a predetermined value. This ensures that the electric motor is reliably disconnected when driving downhill or during sudden deceleration, effectively preventing battery overcharging. Furthermore, by controlling the motor according to the deceleration force, the electric motor can be disconnected only when necessary, without compromising fuel efficiency or battery charging efficiency during normal driving.

[0016] The above configurations (1) to (4) can be combined in any way. In particular, it is desirable to have all of the configurations (1) to (4). This allows the motor to be disconnected at the optimal timing by comprehensively judging the battery status and the vehicle's driving status, thereby achieving high levels of both fuel efficiency improvement and battery protection simultaneously. [Effects of the Invention]

[0017] According to the present invention, when regeneration occurs under conditions where the battery charge level is high, it is possible to provide a vehicle that can improve fuel efficiency by reducing mechanical losses caused by the rotation of the electric motor. [Brief explanation of the drawing]

[0018] [Figure 1] This is an overall front view of a vehicle according to one embodiment of the present invention, with the transmission cover cut out. [Figure 2] This is a skeleton diagram of one embodiment of the transmission shown in Figure 1. [Figure 3] Figure 1 is a block diagram showing the control system of the vehicle. [Figure 4] This is a flowchart illustrating the motor disconnection control performed in the vehicle shown in Figure 1. [Figure 5]This is a diagram showing an example of an efficiency map of an internal combustion engine. [Figure 6] This is a diagram showing an example of an efficiency map of an electric motor.

Modes for Carrying Out the Invention

[0019] 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 constituent components. It should also be noted that the fact that each shaft is rotatably supported by an appropriate bearing or the like 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.

[0020] ≪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 switches and controls the drive sources of the internal combustion engine 3 and the electric motor 4 to change the traveling mode. The vehicle V is provided with a transmission 10. The internal combustion engine 3 and the electric motor 4 are connected to the transmission 10.

[0021] 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 the input shaft 13 of the transmission 10. Therefore, the power output by the internal combustion engine 3 is input to the transmission 10 through the input shaft 13.

[0022] 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, the motor shaft 4A is connected to the 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.

[0023] The transmission 10 has multiple gears and is configured to change the speed of the power generated by the internal combustion engine 3 and the electric motor 4, and to transmit the regenerated energy to the electric motor 4.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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).

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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. In addition, 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 first motor connecting shaft 60A.

[0041] 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.

[0042] As shown in Figure 2, 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.)

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] <<Configuration of the control unit>> As shown in Figure 3, the vehicle V includes an internal combustion engine 3, an electric motor 4, and a battery 6, as well as a detection unit 80 and a control unit 90.

[0055] The detection unit 80 is composed of a group of sensors that acquire information from various parts of the vehicle V and detect the driving state of the vehicle V. The detection unit 80 includes, for example, a vehicle speed sensor, an acceleration sensor, a brake operation detection sensor, an accelerator pedal position sensor, a rotation sensor that detects the rotational speed of the internal combustion engine 3, and a battery sensor that detects the charge state (SOC: State of Charge) of the battery 6.

[0056] The control unit 90 is composed of a microcomputer equipped with a CPU, ROM, RAM, etc. Based on the driving state of the vehicle V detected by the detection unit 80, the control unit 90 controls the drive of the internal combustion engine 3 and the electric motor 4, as well as the switching mechanism 70. More specifically, the control unit 90 controls the clutch 71 of the switching mechanism 70 to be in one of three states: input-side connected state, output-side connected state, or intermediate state. The control unit 90 outputs a control signal to switch between the input-side connected state and the output-side connected state to, for example, a solenoid (not shown) that controls hydraulic pressure.

[0057] ≪Battery and SOC Status≫ The battery 6 supplies power to drive the electric motor 4 and also stores power obtained when the electric motor 4 performs regenerative braking during vehicle V deceleration. The battery 6 is composed of a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride battery.

[0058] The control unit 90 monitors the State of Charge (SOC) of the battery 6 based on the output of the battery sensor of the detection unit 80. SOC is an indicator representing the charge rate (%) of the battery 6, with 100% when the battery 6 is fully charged and 0% when it is completely discharged.

[0059] The control unit 90 determines that the system is in a high SOC state when the SOC value is higher than a predetermined reference charge rate. This reference charge rate is set to, for example, 80%. In other words, the system is determined to be in a high SOC state when the SOC exceeds 80%. In the high SOC state, the battery 6 is sufficiently charged, so further charging is unnecessary or should be suppressed from the standpoint of preventing overcharging.

[0060] ≪Explanation of Driving Modes≫ Vehicle V can selectively use the internal combustion engine 3 and the electric motor 4 as power sources and can operate in various driving modes. The control unit 90 selects the optimal driving mode and controls the internal combustion engine 3 and the electric motor 4 based on conditions such as the driving state of vehicle V, the driver's operation, and the state of charge (SOC) of the battery 6. The main driving modes are the internal combustion engine driving mode (CONV driving), the hybrid driving mode (HEV driving), and the electric motor driving mode (EV driving).

[0061] The internal combustion engine driving mode (CONV driving) is a mode in which the vehicle is driven solely by the internal combustion engine 3. In this mode, the electric motor 4 is not used, or it is charged by power transmission from the internal combustion engine 3. The internal combustion engine driving mode is selected when the State of Charge (SOC) of the battery 6 is low or when driving with only the internal combustion engine 3 is efficient. In the internal combustion engine driving mode, power from the internal combustion engine 3 is transmitted to the drive wheels via the input shaft 13, primary shaft 21, continuously variable transmission 20, and output shaft 15.

[0062] The hybrid driving mode (HEV driving) is a mode in which the vehicle is driven using both the internal combustion engine 3 and the electric motor 4 as power sources. In this mode, the internal combustion engine 3 is the primary power source, while the electric motor 4 provides assistance as needed. The hybrid driving mode is selected when a large amount of driving force is required, such as during acceleration or uphill driving. In hybrid driving mode, the power from the internal combustion engine 3 and the power from the electric motor 4 are combined and transmitted to the drive wheels.

[0063] The electric motor driving mode (EV driving) is a mode in which the vehicle is driven using only the electric motor 4 as the power source. In this mode, the internal combustion engine 3 is stopped. The electric motor driving mode is selected when driving at low speeds or when the state of charge (SOC) of the battery 6 is sufficiently high. In electric motor driving mode, power from the electric motor 4 is transmitted to the drive wheels via the electric motor connecting shaft 60, the switching mechanism 70, the output side gear 33, the output transmission shaft gear 18, the output shaft gear 16, and the output shaft 15.

[0064] ≪Detailed explanation of the switching mechanism≫ The aforementioned switching mechanism 70 includes a first switching mechanism 70A and a second switching mechanism 70B. The first switching mechanism 70A transmits and releases power between the motor connection shaft 60 and the input shaft 13, and in the embodiment, is configured by a clutch 71. The second switching mechanism 70B transmits and releases power between the motor connection shaft 60 and the output shaft 15, and in the embodiment, is configured by the aforementioned clutch 71.

[0065] When the first switching mechanism 70A is engaged and the second switching mechanism 70B is disengaged, the above-mentioned "input-side connection state" is achieved. On the other hand, when the first switching mechanism 70A is disengaged and the second switching mechanism 70B is engaged, the above-mentioned "output-side connection state" is achieved.

[0066] Furthermore, when both the first switching mechanism 70A and the second switching mechanism 70B are in the open state, the motor connecting shaft 60 is disconnected from both the input shaft 13 and the output shaft 15. This state is called the "intermediate state". In the intermediate state, the motor 4 is completely disconnected from the power transmission system, and power is transmitted only between the internal combustion engine 3 and the drive wheels.

[0067] The clutch 71, which is the second switching mechanism 70B, is controlled by hydraulics or the like and is switched between an engaged state and a disengaged state. When the clutch 71 is engaged, power is transmitted between the motor connecting shaft 60 and the output shaft 15 (output side connected state). When the clutch 71 is disengaged, the motor connecting shaft 60 is disconnected from the output shaft 15. At this time, if the first switching mechanism 70A is also disengaged, the motor 4 is completely disconnected from the power transmission system (intermediate state).

[0068] ≪Explanation of Motor Disconnection Control≫ In conventional parallel hybrid vehicles, the drive source and power transmission path were switched according to the State of Charge (SOC). For example, in high SOC conditions, it was common to use the power transmission path shown in green (output side connection state) to drive in hybrid driving mode (HEV driving) or electric motor driving mode (EV driving).

[0069] However, in a high SOC state, when the electric motor 4 enters a regenerative state during hybrid driving mode (HEV driving) or engine driving mode (CONV driving), even though charging of the battery 6 is unnecessary, mechanical losses occur due to the rotation of the electric motor 4, resulting in a deterioration of fuel efficiency.

[0070] In the vehicle V of this embodiment, when the motor 4 is in a regenerative state due to the transmission of driving force from the drive wheels in a high SOC state, control is implemented to completely disconnect the motor 4 from the power transmission path. Specifically, both the first switching mechanism 70A and the second switching mechanism 70B are set to the open state, and the motor connecting shaft 60 is disconnected from both the input shaft 13 and the output shaft 15, resulting in an intermediate state.

[0071] Motor disconnection control is performed only when all of the following conditions are met. (1) Battery 6 is in a high SOC state (charge level is higher than a predetermined standard charge level) (2) The electric motor 4 is in a regenerative state due to the transmission of driving force from the drive wheels. (3) The running efficiency of the internal combustion engine 3 alone is higher than the running efficiency of the combination of the internal combustion engine 3 and the electric motor 4.

[0072] Here, Figure 5 shows an example of an efficiency map for an internal combustion engine, and Figure 6 shows an example of an efficiency map for an electric motor. As shown in Figure 5, in the efficiency map for internal combustion engine 3, the horizontal axis is engine speed (rpm) and the vertical axis is torque (Nm), and efficiency is represented by isofuel ratios (g / kWh). Smaller values ​​indicate better fuel efficiency (higher efficiency). On the other hand, as shown in Figure 6, in the efficiency map for electric motor 4, the horizontal axis is engine speed (rpm) and the vertical axis is torque (Nm), and the difference in concentration represents the level of efficiency.

[0073] A comparison of the driving efficiency of the internal combustion engine 3 alone and the driving efficiency of the combination of the internal combustion engine 3 and the electric motor 4 is performed based on engine efficiency maps and motor efficiency maps, such as those shown in Figures 5 and 6. For example, in the efficiency map of Figure 5, the efficiency of the internal combustion engine 3 alone is relatively good in the high-speed, medium-load region. On the other hand, as shown in Figure 6, the electric motor 4 generally has high efficiency in the low-speed, medium-load region and tends to have decreased efficiency in the high-speed region. Thus, the efficient regions may differ between the internal combustion engine 3 and the electric motor 4, and in certain driving conditions, such as high-speed driving, it may be more efficient overall to drive with the internal combustion engine 3 alone than to use the electric motor 4 in combination.

[0074] ≪Specific procedure for motor disconnection control≫ The specific procedure for motor disconnection control will now be described. The control unit 90 performs motor disconnection control in the following procedure.

[0075] First, the control unit 90 monitors the State of Charge (SOC) of the battery 6 based on information from the battery sensor of the detection unit 80. When the SOC exceeds a predetermined reference charge level (e.g., 80%), it determines that the battery is in a high SOC state.

[0076] Next, the control unit 90 monitors the driving state of the vehicle V and determines whether the electric motor 4 is in a regenerative state based on the power transmission from the drive wheels. Specifically, it determines whether the vehicle V is in a deceleration state based on information from the vehicle speed sensor, brake operation detection sensor, acceleration sensor, etc. of the detection unit 80. It determines whether the vehicle is in a regenerative state by detecting whether the brakes are being applied, whether the vehicle is driving with the accelerator off, or whether the longitudinal acceleration of the vehicle V is a negative value (deceleration state).

[0077] Furthermore, the control unit 90 compares the driving efficiency of the internal combustion engine 3 alone with the driving efficiency of the combination of the internal combustion engine 3 and the electric motor 4. This comparison is performed based on pre-stored engine efficiency maps and motor efficiency maps, as shown in Figures 5 and 6, and the current driving conditions (vehicle speed, required torque, etc.). For example, in the high-speed, medium-load region shown in Figure 5, such as during high-speed driving, the driving efficiency of the internal combustion engine 3 alone is high, and the efficiency of the electric motor 4 shown in Figure 6 is relatively low, so it is determined that the driving efficiency of the internal combustion engine 3 alone is high. When such a state is determined, it is determined that the conditions for motor disconnection control have been met.

[0078] If all of these conditions are met, the control unit 90 outputs a control signal to release both the first switching mechanism 70A and the second switching mechanism 70B. This disconnects the motor connection shaft 60 from both the input shaft 13 and the output shaft 15, completely isolating the motor 4 from the power transmission path.

[0079] ≪Explanation of Operation Example≫ We will explain the operation of motor disconnection control by considering several scenarios.

[0080] [Scene 1: Transition from normal operation to motor disconnection control] Let's assume that when vehicle V is traveling at a constant speed on a highway or similar road, the State of Charge (SOC) of battery 6 is in a high SOC state (e.g., 85%). In this state, when the driver starts to decelerate by pressing the brakes, power from the drive wheels is normally transmitted to the electric motor 4, and regenerative power generation occurs.

[0081] However, since battery 6 is already sufficiently charged, no further charging is necessary. Also, if the control unit 90 determines that the driving efficiency of the internal combustion engine 3 alone is higher than that of the combination of the internal combustion engine 3 and the electric motor 4 at the current vehicle speed range, it will release both the first switching mechanism 70A and the second switching mechanism 70B. As a result, the electric motor 4 is disconnected from the power transmission path, and mechanical losses caused by the rotation of the electric motor 4 are eliminated.

[0082] [Scene 2: Motor disconnection control during deceleration] Assume that vehicle V is traveling downhill and the state of charge (SOC) of battery 6 is in a high SOC state. Normally, regenerative braking charges battery 6 on a downhill slope, but charging needs to be suppressed when the SOC state is high. In this case, when the control unit 90 detects that the deceleration force acting on the drive wheels exceeds a predetermined value, it releases both the first switching mechanism 70A and the second switching mechanism 70B, thereby disconnecting the electric motor 4 from the power transmission path.

[0083] This prevents unnecessary power transmission to the electric motor 4, improving fuel efficiency. It also prevents overcharging of the battery 6.

[0084] ≪Explanation of the control flowchart≫ Figure 5 is a flowchart showing the processing procedure for motor disconnection control. This control is repeatedly performed by the control unit 90, for example, at predetermined time intervals.

[0085] First, in step S101, the control unit 90 obtains the State of Charge (SOC) of the battery 6 and determines whether it is in a high SOC state. If the SOC is higher than a predetermined reference charge level (e.g., 80%), it determines that it is in a high SOC state and proceeds to step S102. Otherwise, the process ends.

[0086] In step S102, the control unit 90 determines from the vehicle V's driving state whether the electric motor 4 is in a regenerative state due to the transmission of driving force from the drive wheels. If it is in a regenerative state, the process proceeds to step S103; otherwise, the process ends.

[0087] In step S103, the control unit 90 compares the running efficiency of the internal combustion engine 3 alone with the running efficiency of the combination of the internal combustion engine 3 and the electric motor 4. If the running efficiency of the internal combustion engine 3 alone is higher, the process proceeds to step S104; otherwise, the process ends.

[0088] In step S104, the control unit 90 outputs a control signal to open both the first switching mechanism 70A and the second switching mechanism 70B, thereby disconnecting the motor 4 from the power transmission path.

[0089] In step S105, the control unit 90 determines whether to continue the motor disconnection control. Specifically, it determines whether any of the conditions in steps S101 to S103 are no longer met. If the conditions remain met, the motor disconnection control is continued; otherwise, the process proceeds to step S106.

[0090] In step S106, the control unit 90 controls the first switching mechanism 70A and the second switching mechanism 70B to return to the appropriate state according to the driving conditions. For example, it may set them to the input side connection state to return to the normal internal combustion engine driving mode, or to the output side connection state to restart regeneration.

[0091] ≪Variations≫ Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention. Several modifications will be described below.

[0092] [Examples of changes regarding switching conditions] In the embodiment described above, three conditions were set for motor disconnection control: (1) the battery is in a high state of charge (SOC) state, (2) the electric motor is in a regenerative state due to power transmission from the drive wheels, and (3) the driving efficiency of the internal combustion engine alone is higher than the driving efficiency of the internal combustion engine and electric motor combined. However, these conditions are not mandatory, and it is possible to perform control using only some of the conditions depending on the situation.

[0093] For example, motor disconnection control can be implemented under two conditions: the battery is in a high state of charge (SOC) state, and the motor is in a regenerative state due to power transmission from the drive wheels. Furthermore, a complex decision-making method can be adopted for comparing driving efficiency, taking into account various factors such as vehicle speed, required torque, and battery SOC.

[0094] [Variations depending on the type of electric motor] In the embodiment described above, we assumed an electric motor with the characteristics shown in Figure 6, but it is also possible to change the control conditions depending on the type and characteristics of the electric motor. Electric motors have various characteristics, such as motors that are efficient in the low-speed range and motors that are efficient in the high-speed range. Since the efficiency map of a motor differs depending on the type of electric motor, it is possible to optimize the vehicle speed range and load conditions for motor disconnection control according to the characteristics of each motor.

[0095] [Modified examples of the structure of the second switching mechanism] In the embodiments described above, the second switching mechanism was described as a dog clutch, but other types of clutches and mechanisms can also be used. For example, multi-plate clutches, friction clutches, electromagnetic clutches, etc., can be used. Furthermore, the position and structure of the dog clutch can be appropriately changed according to the design of the transmission.

[0096] [Variations regarding control timing] Various variations are possible regarding the timing of motor disconnection control. For example, the control timing can be adjusted according to the deceleration rate and the accuracy of the deceleration prediction. By implementing motor disconnection control earlier when a sudden deceleration is predicted, or by delaying the control timing depending on the situation when a gradual deceleration is predicted, more efficient control becomes possible.

[0097] [Variations in Hybrid System Configuration] In this embodiment, a parallel hybrid system was described as an example, but the present invention is also applicable to other types of hybrid systems, such as series hybrid systems and series-parallel hybrid systems. The method of disconnecting the motor and the control conditions can be appropriately adjusted according to the respective system configuration.

[0098] <Effects> Vehicle V of this embodiment has the following characteristic configurations (a) to (d). Therefore, vehicle V can achieve the following unique effects that cannot be achieved with prior art.

[0099] (a) The vehicle V of this embodiment is equipped with an internal combustion engine 3, an electric motor 4, and a battery 6, and is a vehicle that changes the driving mode by switching control of the drive sources of the internal combustion engine 3 and the electric motor 4, and the vehicle V has a transmission 10, the transmission 10 has 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 shaft that transmits power between the input shaft 13 and the electric motor connection shaft 60, an output shaft 15 that transmits power to the drive wheels of the vehicle V, and an input side connection state that enables the transmission of power between the electric motor connection shaft 60 and the input shaft 13 and electric The system includes a switching mechanism 70 that switches between an output-side connection state that enables power transmission between the motor connection shaft 60 and the output shaft 15, a detection unit 80 that detects the driving state of the vehicle V, and a control unit 90 that controls the operation of the switching mechanism 70. The system controls the switching mechanism 70 to an intermediate state in which the motor connection shaft 60 is disconnected from both the input shaft 13 and the output shaft 15, provided that the battery 6 is in a high-state-of-charge (SOC) state with a charge rate higher than a predetermined reference charge rate, and the motor 4 is in a regenerative state due to power transmission from the drive wheels or from the internal combustion engine 3.

[0100] In this embodiment, as described in (a) above, the vehicle V controls the switching mechanism 70 to an intermediate state in which the motor connection shaft 60 is disconnected from both the input shaft 13 and the output shaft 15 when in a high SOC state and regenerative state. As a result, the motor 4 is completely disconnected from the power transmission path, eliminating mechanical losses caused by the motor 4 rotating together, and improving fuel efficiency. In addition, by stopping the regeneration of the motor 4 in the high SOC state where charging is not required, overcharging of the battery 6 can be prevented.

[0101] (b) The vehicle V of this embodiment has a switching mechanism 70 comprising a first switching mechanism 70A that transmits and releases power between the motor connecting shaft 60 and the input shaft 13, and a second switching mechanism 70B that transmits and releases power between the motor connecting shaft 60 and the output shaft 15, and the control unit 90 sets the vehicle to an intermediate state by releasing both the first switching mechanism 70A and the second switching mechanism 70B, provided that the charge level of the battery 6 is in a high state of charge (SOC) state and the motor 4 is in a regenerative state due to power transmission from the drive wheels or the internal combustion engine.

[0102] In this embodiment, the vehicle V achieves an intermediate state by releasing both the first switching mechanism 70A and the second switching mechanism 70B, as described in (b) above. This ensures that the motor connecting shaft 60 is reliably disconnected from both the input shaft 13 and the output shaft 15, effectively preventing mechanical losses due to the motor 4 rotating together. Furthermore, by appropriately adjusting the engagement state of the first switching mechanism 70A and the second switching mechanism 70B, it is possible to flexibly switch the power transmission path according to the driving state of the vehicle V. Note that the specific configurations of the first switching mechanism 70A and the second switching mechanism 70B are not limited to the configuration described in this embodiment and can take various forms.

[0103] (c) In this embodiment, the control unit 90 controls the switching mechanism 70 to enter an intermediate state, provided that the running efficiency of the internal combustion engine 3 alone is higher than the running efficiency of the internal combustion engine 3 and the electric motor 4.

[0104] In this embodiment, as described in (c) above, the vehicle V compares the driving efficiency of the internal combustion engine 3 alone with the driving efficiency of the internal combustion engine 3 and the electric motor 4, and enters an intermediate state when the driving efficiency of the internal combustion engine 3 alone is higher. This makes it possible to always select the most efficient driving mode, and maximizes the overall fuel efficiency of the vehicle V. Furthermore, in areas where the electric motor 4 does not operate efficiently (for example, in high-speed areas), further fuel efficiency improvements can be obtained by completely disconnecting the electric motor 4. It should be noted that in order to obtain the effects of this embodiment, it is not always necessary to compare the driving efficiency of the internal combustion engine 3 alone with the driving efficiency of the internal combustion engine 3 and the electric motor 4, and it is also possible to determine the transition to an intermediate state based on other conditions.

[0105] (d) In this embodiment, the vehicle V is controlled by the control unit 90 to enter an intermediate state when the battery 6 is in a high state of charge state (SOC) state and the deceleration force acting on the drive wheels exceeds a predetermined value.

[0106] In this embodiment, vehicle V enters an intermediate state when the deceleration force acting on the drive wheels exceeds a predetermined value in a high SOC state, as described in (d) above. This ensures that the electric motor 4 is reliably disconnected in situations where strong regeneration occurs, such as when driving downhill or during sudden deceleration, effectively preventing overcharging of the battery 6. Furthermore, by controlling the system according to the deceleration force, the electric motor 4 can be disconnected only when necessary, without compromising fuel efficiency or battery charging efficiency during normal driving. It should be noted that obtaining the effects of this embodiment does not necessarily require the deceleration force acting on the drive wheels as a condition; the transition to the intermediate state can also be determined by other conditions.

[0107] The above configurations (a) to (d) can be combined in any way. In particular, it is desirable to have all of the configurations (a) to (d). This allows the electric motor 4 to be disconnected at the optimal timing by comprehensively judging the state of the battery 6 and the driving state of the vehicle V, thereby achieving both improved fuel efficiency and protection of the battery 6 at a high level simultaneously.

[0108] 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]

[0109] 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]

[0110] 3: Internal combustion engine 4: Electric motor 6: Battery 10: Transmission 13: Input axis 15: Output axis 51: Forward clutch 55: Reverse clutch 60: Motor connecting shaft 70: Switching mechanism 70A: First switching mechanism 70B: Second switching mechanism 71: Clutch 80: Detection unit 90: Control Unit V: Vehicle

Claims

1. A vehicle comprising an internal combustion engine, an electric motor, and a battery, wherein the driving mode is changed by switching and controlling the drive source of the internal combustion engine and the electric motor, The aforementioned vehicle has a transmission, The aforementioned transmission is, An input shaft that transmits power output from the internal combustion engine, The motor connection shaft connected to the aforementioned motor, A switching shaft that transmits power between the input shaft and the motor connection shaft, An output shaft that transmits power to the drive wheels of the aforementioned vehicle, A switching mechanism that switches between an input-side connection state that enables the transmission of power between the motor connection shaft and the input shaft and an output-side connection state that enables the transmission of power between the motor connection shaft and the output shaft, A detection unit for detecting the driving state of the vehicle, A control unit that controls the operation of the switching mechanism, Equipped with, A vehicle characterized by controlling the switching mechanism to an intermediate state in which the motor connecting shaft is disconnected from both the input shaft and the output shaft, provided that the charge level of the battery is in a high state of charge (SOC) state, which is higher than a predetermined reference charge level, and the motor is in a regenerative state due to power transmission from the drive wheels or from the internal combustion engine.

2. The aforementioned switching mechanism is A first switching mechanism that transmits and releases the power between the motor connecting shaft and the input shaft, A second switching mechanism for transmitting and releasing the power between the motor connection shaft and the output shaft, Equipped with, The vehicle according to claim 1, characterized in that the control unit sets the intermediate state by releasing both the first switching mechanism and the second switching mechanism, provided that the battery charge level is in the high SOC state and the electric motor is in a regenerative state due to power transmission from the drive wheels or from the internal combustion engine.

3. The vehicle according to claim 1 or 2, characterized in that the control unit controls the switching mechanism to enter the intermediate state, on the condition that the driving efficiency of the internal combustion engine alone is higher than the driving efficiency of the internal combustion engine and the electric motor combined.

4. The vehicle according to claim 1 or 2, characterized in that the control unit controls the switching mechanism to enter the intermediate state, provided that the deceleration force acting on the drive wheels exceeds a predetermined value when the battery charge level is in the high SOC state.

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