vehicle

Abstract

The objective is to provide a vehicle that can reduce mechanical losses in electric motor driving mode and improve fuel efficiency. [Solution] A vehicle V equipped with an internal combustion engine 3 and an electric motor 4 has a transmission 10 that switches and controls the driving mode. The transmission 10 includes an input shaft 13, an electric motor connection shaft 60, a switching shaft, and an output shaft 15, and switches between the input side connection state and the output side connection state by a first switching mechanism 70. The vehicle V also includes a second switching mechanism and a continuously variable transmission mechanism 20. The continuously variable transmission mechanism 20 has a belt 28 between a primary pulley 26 and a secondary pulley 27. In the electric motor driving mode, the vehicle V reduces mechanical losses in the electric motor driving mode and improves fuel efficiency by controlling the belt gear ratio to a gear ratio range where mechanical losses are less than a predetermined threshold.

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 drive sources for 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 (for example, Patent Document 1). 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 using regenerative torque during vehicle braking.

[0003] In this type of hybrid vehicle, the internal combustion engine may be brought into a stopped state, and the vehicle may travel in an electric motor travel mode using only the driving force of the electric motor. In this electric motor travel mode, power transmission to the internal combustion engine is interrupted by releasing the clutch of the transmission.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] However, in the electric motor travel mode, although the clutch of the transmission is released, the pulley portion rotates idly in synchronization with the rotation of the wheels. For this reason, mechanical loss occurs in the pulley portion, which causes a reduction in driving force and a reduction in regenerative efficiency. Accordingly, there has been a problem in fuel efficiency performance in the EV travel mode.

[0006] Accordingly, an object of the present invention is to provide a vehicle capable of reducing mechanical loss in the electric motor travel mode and improving fuel efficiency performance. [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 sources of the internal combustion engine and the electric motor, the vehicle having a transmission, the transmission having 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 a switch provided on the switching shaft that enables an input-side connection state that enables the transmission of power between the electric motor connection shaft and the input shaft and enables the transmission of power between the electric motor connection shaft and the output shaft. The transmission comprises a first switching mechanism for switching between an output-side connection state and a second switching mechanism for transmitting and releasing power between the motor connection shaft and the output shaft, and a continuously variable transmission mechanism in the transmission that can continuously change the gear ratio between the input shaft and the output shaft, wherein the continuously variable transmission mechanism has a primary pulley, a secondary pulley, and a belt stretched between the primary pulley and the secondary pulley, and in the motor-driven mode in which the vehicle is driven solely by the power of the motor, the belt gear ratio of the continuously variable transmission mechanism is controlled to be in a predetermined gear ratio range in which mechanical losses are less than a predetermined threshold.

[0008] The vehicle of the present invention controls the belt gear ratio of the continuously variable transmission mechanism in electric motor driving mode so that the mechanical loss is within a predetermined gear ratio range where the mechanical loss is less than a predetermined threshold. This reduces the mechanical loss in the pulley section in electric motor driving mode, thereby improving driving force and regenerative efficiency. As a result, the vehicle of the present invention can improve fuel efficiency in electric motor driving mode.

[0009] (2) The vehicle of the present invention is characterized in that the predetermined gear ratio range includes a gear ratio in which the belt gear ratio γ is 1.

[0010] The vehicle of the present invention controls the gear ratio to include a gear ratio in a predetermined gear ratio range where the belt gear ratio γ is 1. A belt gear ratio γ=1 means that the diameter ratio of the primary pulley and the secondary pulley are equal, and in this state the belt transmission efficiency is best and mechanical losses are minimized. This effectively reduces mechanical losses in the pulley section in the electric motor driving mode and maximizes the driving force and regenerative efficiency.

[0011] (3) The vehicle of the present invention is characterized in that, in the electric motor driving mode, the belt gear ratio is controlled to the predetermined gear ratio range only within a predetermined vehicle speed range.

[0012] The vehicle of the present invention controls the belt gear ratio to a predetermined gear ratio range only within a predetermined vehicle speed range in the electric motor driving mode. This makes it possible to maximize the effect of reducing mechanical losses within an appropriate vehicle speed range while taking into account constraints such as starting performance at low vehicle speeds and unit protection at high vehicle speeds. As a result, it is possible to balance improved efficiency in the electric motor driving mode with vehicle performance and durability.

[0013] (4) The vehicle of the present invention is characterized in that the predetermined vehicle speed range has a lower limit and an upper limit, and at vehicle speeds lower than the lower limit, the belt gear ratio is controlled to the low side, and at vehicle speeds higher than the upper limit, the belt gear ratio is controlled to suppress the rotational speed of the primary pulley to a predetermined value or less.

[0014] The vehicle of the present invention controls the belt gear ratio to the low side at vehicle speeds below the lower limit of a predetermined vehicle speed range, and controls the belt gear ratio to suppress the rotational speed of the primary pulley to below a predetermined value at vehicle speeds above the upper limit. By controlling the belt gear ratio to the low side in the vehicle speed range below the lower limit, responsiveness when the vehicle restarts can be ensured. Furthermore, by suppressing the rotational speed of the primary pulley to below a predetermined value in the vehicle speed range above the upper limit, the durability of the continuously variable transmission mechanism can be ensured. This makes it possible to achieve both improved fuel efficiency in electric motor driving mode and the assurance of vehicle performance and durability.

[0015] (5) The vehicle of the present invention is characterized in that when transitioning from the electric motor driving mode to a vehicle stopped state, it performs control to return the belt gear ratio to the low side.

[0016] The vehicle of the present invention performs control to return the belt gear ratio to the low side when transitioning from electric motor driving mode to a vehicle stop state. This ensures sufficient driving force when restarting after the vehicle has stopped, enabling a smooth start.

[0017] The configurations described in (1) to (5) above can be used in combination with each other. In particular, by combining configurations (1) to (3), it is possible to maximize the effect of reducing mechanical losses in the electric motor driving mode while achieving appropriate control according to the characteristics of the vehicle and the operating environment. Furthermore, by adding configurations (4) and (5), it is possible to further improve the efficiency of the electric motor driving mode and the practicality of the vehicle.

[0018] The "predetermined gear ratio range in which mechanical losses are less than a predetermined threshold" refers to a certain range centered around the gear ratio in which mechanical losses are minimized, such as a belt gear ratio γ being in the range of 0.95 to 1.05. Since the optimal value of this range may differ depending on the configuration and characteristics of the continuously variable transmission mechanism, an optimal range can be set for each vehicle.

[0019] Furthermore, the "specified vehicle speed range" can be set according to the vehicle's characteristics and required performance. For example, since the lower and upper limits are expected to depend on conditions such as unit specifications and vehicle specifications, it is advisable to set the optimal range for each vehicle. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a vehicle that can reduce mechanical losses in electric motor driving mode and improve fuel efficiency. [Brief explanation of the drawing]

[0021] [Figure 1]FIG. 1 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] FIG. 2 is a skeleton diagram of an embodiment of the transmission of FIG. 1. [Figure 3] FIG. 3 is a conceptual diagram of gear ratio control in an EV travel mode in a vehicle according to an embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart of a main routine related to EV travel mode control executed in a vehicle according to an embodiment of the present invention. [Figure 5] (a) is a flowchart of a low vehicle speed range subroutine executed in a vehicle according to an embodiment of the present invention, and (b) is a flowchart of a high vehicle speed range subroutine. [Figure 6] FIG. 6 is a flowchart of a stop state transition subroutine executed in a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0022] 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 supported by an appropriate bearing or the like and is rotatable may be omitted. Hereinafter, the front side of the vehicle V may be referred to as front Fr, and the rear side thereof may be referred to as rear Rr.

[0023] <<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 a travel mode by performing switching control between the drive sources of the internal combustion engine 3 and the electric motor 4. The vehicle V includes the transmission 10. The internal combustion engine 3 and the electric motor 4 are connected to the transmission 10.

[0024] The internal combustion engine 3 is composed of, for example, a gasoline engine or a diesel engine. The drive shaft (not shown) of the internal combustion engine 3 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.

[0025] As shown in Figures 1 and 2, the electric motor 4 is configured, for example, as a motor generator, and can output driving force and generate electricity. The motor shaft 4A (see Figure 5) of the electric motor 4 is connected to the motor connection shaft 60 in 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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).

[0036] 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.

[0037] 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).

[0038] 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.

[0039] 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).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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. As shown in Figure 6, 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.)

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] ≪EV Driving Mode Control≫ The EV driving mode control performed in vehicle V of this embodiment will be described in detail below.

[0058] The electric motor driving mode (EV driving mode) is a driving mode in the transmission 10 of a hybrid vehicle V equipped with an internal combustion engine 3 and an electric motor 4, in which the vehicle is driven solely by the power of the electric motor 4.

[0059] Vehicle V has a transmission 10 and can achieve an output-side connection state that enables power transmission between the motor connection shaft 60 and the output shaft 15. In this EV driving mode, by disengaging both the forward clutch 51 and the reverse clutch 55, power transmission to the internal combustion engine 3 via the primary shaft 21 and the secondary shaft 23 is interrupted.

[0060] In this embodiment, the vehicle V performs control to reduce mechanical loss in the pulley section 80 (primary pulley 26 and secondary pulley 27) in EV driving mode. The pulley section 80 has the characteristic of generating mechanical loss when it rotates in sync with the rotation of the wheels.

[0061] Therefore, in this embodiment, in EV driving mode, the belt gear ratio of the continuously variable transmission mechanism 20 is controlled to be in a gear ratio region (mechanical loss suppression gear ratio region) in which mechanical loss is less than a first threshold. Specifically, it is controlled to a gear ratio region that includes a gear ratio in which the belt gear ratio γ is 1. Here, a belt gear ratio γ=1 means that the diameter ratio of the primary pulley 26 and the secondary pulley 27 are equal, and in this state the transmission efficiency of the belt 28 is best and mechanical loss is minimized.

[0062] This control reduces mechanical losses in the pulley section 80 during EV driving mode, thereby improving driving force and regenerative efficiency. This improves the fuel efficiency of the hybrid vehicle V.

[0063] Furthermore, the vehicle V of this embodiment is characterized by controlling the belt gear ratio so that it falls within the gear ratio range that suppresses mechanical losses only within a predetermined vehicle speed range. Specifically, as shown in Figure 3, the belt gear ratio γ is fixed to approximately 1 only in the range where the vehicle speed is higher than a first predetermined value (lower limit vehicle speed) and lower than a second predetermined value (upper limit vehicle speed).

[0064] In the low-speed range where the vehicle speed is below a first predetermined value (lower limit vehicle speed), the belt gear ratio is controlled to the low side to take starting performance into consideration. In the high-speed range where the vehicle speed is above a second predetermined value (upper limit vehicle speed), the belt gear ratio is appropriately controlled to prevent the rotational speed of the primary pulley 26 from increasing excessively. By considering these constraints and implementing belt gear ratio γ=1 control only within an appropriate vehicle speed range (optimal vehicle speed range), it is possible to balance improved efficiency in EV driving mode with vehicle performance and durability.

[0065] This control effectively reduces mechanical losses in the pulley section 80 during EV driving mode, thereby improving energy efficiency, while simultaneously ensuring good starting performance at low vehicle speeds and protecting the unit at high vehicle speeds above the upper limit.

[0066] ≪Additional control to address constraints≫ The constraints to be considered in the EV driving mode control described above, and the corresponding additional controls, will be explained in detail. These additional controls are called as subroutines from the main routine of the EV driving mode and are executed under specific conditions.

[0067] First, let's explain the control in the low-speed range, which is below the lower limit vehicle speed. In the low-speed range, where the vehicle speed X is below the first predetermined value (lower limit vehicle speed), the belt gear ratio γ is controlled to the low side. The reason for controlling the belt gear ratio γ to the low side in the low-speed range is to ensure responsiveness when the vehicle V restarts.

[0068] In the low-speed range below the lower limit of vehicle speed, if the belt gear ratio γ is fixed around 1, sufficient driving force may not be obtained when the vehicle V restarts from a standstill. In particular, if it is necessary to start the internal combustion engine 3 when restarting, it is necessary to ensure sufficient driving force. Therefore, in the low-speed range, prioritizing responsiveness during restart over the effect of reducing mechanical losses, the belt gear ratio γ is controlled to the low side.

[0069] Specifically, when the vehicle speed X falls below a first predetermined value (lower limit vehicle speed), the hydraulic control of the continuously variable transmission mechanism 20 controls the hydraulic pressure in a direction that widens the groove width of the primary pulley 26, thereby maintaining the belt gear ratio γ on the low side. This ensures responsiveness when the vehicle V transitions to a stopped state or restarts.

[0070] Next, we will explain the control in the high-speed range above the upper limit vehicle speed. In the high-speed range where the vehicle speed X is higher than the second predetermined value (upper limit vehicle speed), the belt gear ratio γ is controlled so that the rotational speed of the primary pulley 26 does not exceed the predetermined value (upper limit rotational speed).

[0071] In the high-speed range above the upper limit of vehicle speed, if the vehicle speed X increases while the belt gear ratio γ is fixed at 1, the rotational speed of the primary pulley 26 will increase proportionally, which may affect the durability of the primary pulley 26 and the continuously variable transmission mechanism 20. Therefore, in the high-speed range, the belt gear ratio γ is controlled to the high side in order to suppress the rotational speed of the primary pulley 26 to below the upper limit of rotational speed.

[0072] Specifically, when the vehicle speed X exceeds a second predetermined value (upper vehicle speed), the hydraulic control of the continuously variable transmission mechanism 20 controls the hydraulic pressure in a direction that narrows the groove width of the primary pulley 26, thereby shifting the belt gear ratio γ to the high side. This ensures that the rotational speed of the primary pulley 26 is appropriately managed even in the high vehicle speed range, and the durability of the continuously variable transmission mechanism 20 can be ensured.

[0073] Finally, let's explain the control when vehicle V transitions to a stop. When vehicle V transitions to a stop, control is performed to return the belt gear ratio γ to the low side. This control is to ensure responsiveness when vehicle V starts up again.

[0074] Specifically, if it is determined that vehicle V is transitioning to a stopping state based on braking or deceleration, control is initiated to return the belt gear ratio γ to the low side before vehicle V comes to a complete stop. As a result, when vehicle V comes to a stop, the belt gear ratio γ is already in the low side, ensuring responsiveness for the next start.

[0075] The above additional controls are called and executed as subroutines within the main routine in EV driving mode when specific conditions are met. By performing control that takes these constraints into account, it is possible to maximize the effect of reducing mechanical losses in EV driving mode while ensuring starting performance at low vehicle speeds below the lower limit, durability at high vehicle speeds above the upper limit, and responsiveness for the next start after transitioning to a stopped state.

[0076] ≪Control flow related to the main routine≫ Next, the flow of the main routine for belt gear ratio control in EV driving mode according to this embodiment will be described. Figure 3 is a flowchart of the belt gear ratio control in EV driving mode according to this embodiment.

[0077] As shown in Figure 4, the control main routine of this embodiment first determines in step 1-1 whether or not the vehicle is in EV driving mode. EV driving mode is a state in which the internal combustion engine 3 is stopped and the vehicle is driven solely by the power of the electric motor 4. If it is determined that the vehicle is in EV driving mode (step 1-1: YES), the process proceeds to step 1-2. If it is determined that the vehicle is not in EV driving mode (step 1-1: NO), the main routine terminates.

[0078] Step 1-2 determines whether the current vehicle speed X is greater than a first predetermined value (lower limit vehicle speed). If it is determined that the vehicle speed X is greater than the first predetermined value (lower limit vehicle speed) (Step 1-2: YES), proceed to Step 1-3. If it is determined that the vehicle speed X is less than or equal to the first predetermined value (lower limit vehicle speed) (Step 1-2: NO), proceed to Step 1-5.

[0079] Step 1-3 determines whether the current vehicle speed X is less than a second predetermined value (upper limit vehicle speed). If it is determined that the vehicle speed X is less than the second predetermined value (upper limit vehicle speed) (Step 1-3: YES), proceed to Step 1-4. If it is determined that the vehicle speed X is equal to or greater than the second predetermined value (upper limit vehicle speed) (Step 1-3: NO), proceed to Step 1-6.

[0080] In steps 1-4, a control (gear ratio adjustment control) is performed to adjust the belt gear ratio γ so that it falls into a gear ratio region where mechanical loss is less than the first threshold (mechanical loss suppression gear ratio region). Specifically, the primary pulley 26 and the secondary pulley 27 are controlled to have equal diameter ratios so that the belt gear ratio γ becomes 1. This minimizes mechanical loss in the pulley section 80 in EV driving mode.

[0081] Step 1-5 calls the "low-speed range subroutine." This subroutine performs additional control in the low-speed range, which is lower than the lower limit speed mentioned above. Since the vehicle speed X is in the low-speed range, which is below the first predetermined value (lower limit speed), the belt gear ratio γ is controlled to the low side to ensure responsiveness when restarting. Specifically, the processes from steps 2-1 to 2-3 of the subroutine (low-speed range subroutine), which will be described in detail later, are executed.

[0082] Step 1-6 calls the "high-speed range subroutine." This subroutine performs additional control in the high-speed range, which is higher than the upper limit speed. Since the vehicle speed X is in the high-speed range, which is above the second predetermined value (upper limit speed), the belt gear ratio γ is controlled so that the rotational speed of the primary pulley 26 does not exceed the upper limit speed, and processing is performed to ensure the durability of the continuously variable transmission mechanism 20. Specifically, the processing from steps 3-1 to 3-3 of the subroutine (high-speed range subroutine), which will be described in detail later, is executed.

[0083] Step 1-7 determines whether vehicle V will enter a stopping state. This can be determined from information such as brake operation and deceleration. If it is determined that vehicle V will enter a stopping state (Step 1-7: YES), proceed to Step 1-8. If it is determined that vehicle V will not enter a stopping state (Step 1-7: NO), return to Step 1-1 and repeat the main routine starting from the EV driving mode determination.

[0084] Step 1-8 calls the "Stop State Transition Subroutine". This subroutine performs additional control when the vehicle V transitions to a stop state. Specifically, before the vehicle V comes to a complete stop, it controls the belt gear ratio γ to the low side to ensure responsiveness for the next start. Specifically, it executes the processes in steps 4-1 to 4-3 of the subroutine, which will be described in detail later.

[0085] ≪Control flow related to subroutines≫ Next, we will explain the details of the subroutine. First, as shown in Figure 5(a), the "low vehicle speed subroutine" consists of the following steps. In step 2-1, it is confirmed that the vehicle speed X is less than or equal to a first predetermined value (lower limit vehicle speed). In step 2-2, the hydraulic control of the continuously variable transmission mechanism 20 controls the hydraulic pressure in a direction that widens the groove width of the primary pulley 26. In step 2-3, it is confirmed that the belt gear ratio γ is maintained on the low side, and the process returns to the main routine.

[0086] As shown in Figure 5(b), the "high-speed subroutine" consists of the following steps. Step 3-1 confirms that the vehicle speed X is equal to or greater than a second predetermined value (upper limit vehicle speed). Step 3-2 calculates the rotational speed of the primary pulley 26 and compares it with the predetermined upper limit rotational speed. Step 3-3 adjusts the belt gear ratio γ to the high side by hydraulic control of the continuously variable transmission mechanism 20 so that the rotational speed of the primary pulley 26 does not exceed the predetermined upper limit rotational speed, and returns to the main routine.

[0087] As shown in Figure 6, the "stop state transition subroutine" consists of the following steps: Step 4-1 detects the vehicle V's intention to stop from the brake operation or deceleration. Step 4-2 controls the hydraulic pressure of the continuously variable transmission mechanism 20 to widen the groove width of the primary pulley 26. Step 4-3 confirms that the belt gear ratio γ has returned to the low side before the vehicle V stops, and returns to the main routine.

[0088] The combination of the main and subroutines described above enables optimal belt gear ratio control in EV driving mode according to vehicle speed and vehicle condition, achieving both reduced mechanical losses and ensured vehicle performance. In particular, by fixing the belt gear ratio γ to around 1 within a predetermined vehicle speed range (appropriate vehicle speed range), mechanical losses can be minimized and the effect of improving electric efficiency can be maximized.

[0089] ≪Variations≫ The control of the transmission 10 described in this embodiment can be modified in various ways and has a range of applications. These modifications and ranges of applications will be described below.

[0090] First, we will explain some variations of the belt gear ratio γ. In this embodiment, we have described controlling the belt gear ratio γ to be around 1 in EV driving mode, but the optimal value of the belt gear ratio γ may differ slightly depending on the configuration and characteristics of the continuously variable transmission mechanism 20.

[0091] Specifically, depending on the specifications of the belt and the precision of the pulley, the optimal point for reducing mechanical loss may be a value slightly off from γ=1 (for example, in the range of 0.95 to 1.05), rather than exactly γ=1. Therefore, the present invention is not strictly limited to a belt gear ratio γ=1, and it is preferable to control the gear ratio range in which mechanical loss is less than a predetermined threshold.

[0092] In actual application, it is desirable to determine the belt gear ratio γ that minimizes mechanical loss for each transmission 10 through experiments or simulations and set it to that value. This allows for the optimal reduction of mechanical loss according to the characteristics of each transmission 10.

[0093] Next, we will describe some variations regarding the vehicle speed range (appropriate vehicle speed range). In this embodiment, we have explained that the belt gear ratio γ is controlled to be around 1 in a range where the vehicle speed X is higher than a first predetermined value (lower limit vehicle speed) and lower than a second predetermined value (upper limit vehicle speed), but this vehicle speed range (appropriate vehicle speed range) is changeable.

[0094] Furthermore, it is possible to set more detailed control conditions by adding conditions such as accelerator opening and required torque, in addition to vehicle speed X. For example, it is possible to set conditions such as controlling the belt gear ratio γ to around 1 only during cruising with a small accelerator opening, and controlling the belt gear ratio γ to the low side when accelerating with a large accelerator opening.

[0095] Furthermore, the control described in this embodiment can also be applied to the starting conditions of the internal combustion engine 3. For example, when transitioning from EV driving mode to HEV driving mode (a driving mode that uses both the internal combustion engine 3 and the electric motor 4), belt gear ratio control can be performed with consideration for ensuring sufficient driving force. Specifically, when a request to start the internal combustion engine 3 is made, the belt gear ratio γ can be shifted to the low side in advance before starting the internal combustion engine 3, thereby achieving a smoother transition to driving.

[0096] Finally, the control described in this embodiment is applicable to various hybrid vehicles as long as the configuration of the transmission 10 is similar. Specifically, the control of the present invention can be applied to any vehicle equipped with an internal combustion engine 3 and an electric motor 4, and a transmission 10 having a continuously variable transmission mechanism 20.

[0097] As described above, the control described in this embodiment has various modifications and application ranges, and can realize optimal control according to the characteristics and required performance of each vehicle V. This makes it possible to further improve the fuel efficiency and driving performance of the hybrid vehicle V.

[0098] <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.

[0099] (a) The vehicle V of this embodiment is equipped with an internal combustion engine 3 and an electric motor 4, 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 a switch provided on the switching shaft 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 The transmission 10 comprises a first switching mechanism 70 for switching, a second switching mechanism for transmitting and releasing power between the motor connection shaft 60 and the output shaft 15, and a continuously variable transmission mechanism 20 that can continuously change the gear ratio between the input shaft 13 and the output shaft 15. The continuously variable transmission mechanism 20 has a primary pulley 26, a secondary pulley 27, and a belt 28 stretched between the primary pulley 26 and the secondary pulley 27. In the motor-driven mode, where the vehicle is driven solely by the power of the motor 4, the belt gear ratio of the continuously variable transmission mechanism 20 is controlled to be in a predetermined gear ratio range where mechanical loss is less than a predetermined threshold.

[0100] In this embodiment, the vehicle V controls the belt gear ratio of the continuously variable transmission mechanism 20 in the electric motor driving mode so that the mechanical loss is within a predetermined gear ratio range where the mechanical loss is less than a predetermined threshold. This reduces the mechanical loss of the pulley section 80 in the electric motor driving mode, thereby improving the driving force and regenerative efficiency. As a result, fuel efficiency in the electric motor driving mode can be improved.

[0101] (b) The vehicle V of this embodiment is characterized in that a predetermined gear ratio range includes a gear ratio range in which the belt gear ratio γ is 1.

[0102] In this embodiment, the vehicle V is controlled to a predetermined gear ratio range that includes a gear ratio where the belt gear ratio γ is 1. A belt gear ratio γ=1 means that the diameter ratio of the primary pulley 26 and the secondary pulley 27 are equal. In this state, the transmission efficiency of the belt 28 is best, and mechanical losses are minimized. This effectively reduces mechanical losses in the pulley section 80 in the electric motor driving mode, and maximizes the improvement of driving force and regenerative efficiency.

[0103] 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 with some or all of the configuration described in (b) above. For example, the gear ratio that minimizes mechanical loss may not necessarily be γ=1 depending on the configuration and characteristics of the transmission 10, so it is also possible to set the optimal gear ratio range based on the actual mechanical loss measurement results.

[0104] (c) The vehicle V of this embodiment is characterized in that, in the electric motor driving mode, the belt gear ratio is controlled to a predetermined gear ratio range only within a predetermined vehicle speed range (appropriate vehicle speed range).

[0105] In this embodiment, vehicle V controls the belt gear ratio to a predetermined gear ratio range only within a predetermined vehicle speed range (appropriate vehicle speed range) in the electric motor driving mode. This maximizes the effect of reducing mechanical losses within an appropriate vehicle speed range while considering constraints such as starting performance in the low vehicle speed range below the lower limit and unit protection in the high vehicle speed range above the upper limit. As a result, it is possible to balance improved efficiency in the electric motor driving mode with vehicle performance and durability.

[0106] 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 with some or all of the configuration described in (c) above. For example, depending on the operating environment and required performance of the vehicle V, it may be possible to prioritize higher fuel efficiency by controlling the gear ratio to minimize mechanical losses at all times, regardless of vehicle speed. However, in that case, separate measures will be required to ensure starting performance and durability.

[0107] (d) The vehicle V of this embodiment is characterized in that the predetermined vehicle speed range (appropriate vehicle speed range) has a lower limit and an upper limit, and at vehicle speeds lower than the lower limit, the belt gear ratio is controlled to the low side, and at vehicle speeds higher than the upper limit, the belt gear ratio is controlled to suppress the rotational speed of the primary pulley 26 to a predetermined value or less.

[0108] In this embodiment, the vehicle V controls the belt gear ratio to the low side at vehicle speeds below the lower limit of a predetermined vehicle speed range (appropriate vehicle speed range), and controls the belt gear ratio to suppress the rotational speed of the primary pulley 26 to below a predetermined value at vehicle speeds above the upper limit. By controlling the belt gear ratio to the low side in the vehicle speed range below the lower limit, responsiveness when restarting the vehicle V can be ensured. Furthermore, by suppressing the rotational speed of the primary pulley 26 to below a predetermined value in the vehicle speed range above the upper limit, the durability of the continuously variable transmission mechanism 20 can be ensured. This makes it possible to achieve both improved fuel efficiency in electric motor driving mode and the assurance of vehicle performance and durability.

[0109] 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 equipped with some or all of the configuration described in (d) above. For example, depending on the vehicle V, if fuel efficiency is prioritized over starting performance in the low-speed range below the lower limit vehicle speed, or if there is sufficient durability of the primary pulley 26 in the high-speed range above the upper limit vehicle speed, it is possible to change the settings of the lower limit and upper limit values ​​or relax these constraints.

[0110] (e) The vehicle V of this embodiment is characterized by performing control to return the belt gear ratio to the low side when transitioning from the electric motor driving mode to the vehicle stopping state.

[0111] In this embodiment, when the vehicle V transitions from electric motor driving mode to a stopped state, it performs control to return the belt gear ratio to the low side. This ensures sufficient driving force when restarting after the vehicle V has stopped, enabling a smooth start. In particular, when restarting by starting the internal combustion engine 3, the low side of the belt gear ratio also has the effect of improving the starting performance of the internal combustion engine 3.

[0112] 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 some or all of the configuration described in (e) above. For example, in a system where it is assumed that the vehicle will always start in electric motor mode when restarting, it may not always be necessary to return the belt gear ratio to the low side when stopped. It is also possible to employ advanced control that predicts the situation when restarting and selects an appropriate belt gear ratio.

[0113] The configurations described in (a) to (e) above can be used in combination with each other. In particular, by combining configurations (a) to (c), it is possible to maximize the effect of reducing mechanical losses in the electric motor driving mode while achieving appropriate control according to the characteristics of the vehicle V and the operating environment. Furthermore, by adding configurations (d) and (e), it is possible to further improve the efficiency of the electric motor driving mode and the practicality of the vehicle V.

[0114] 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]

[0115] 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]

[0116] 3: Internal combustion engine 4: Electric motor 10: Transmission 13: Input axis 15: Output axis 20: Continuously Variable Speed ​​Mechanism 26: Primary Pulley 27: Secondary pulley 28: Belt 60: Motor connecting shaft 70: First switching mechanism 80: Pulley section V: Vehicle γ: Belt gear ratio

Claims

1. A vehicle equipped with an internal combustion engine and an electric motor, which changes the driving mode by switching and controlling the drive sources 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 first switching mechanism is provided on the switching shaft and 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 second switching mechanism for transmitting and releasing power between the motor connection shaft and the output shaft, The transmission includes a continuously variable transmission mechanism that allows the gear ratio to be changed steplessly between the input shaft and the output shaft, Equipped with, The aforementioned continuously variable transmission mechanism includes a primary pulley, a secondary pulley, and a belt stretched between the primary pulley and the secondary pulley. A vehicle characterized in that, in an electric motor driving mode in which the vehicle is driven solely by the power of the electric motor, the belt gear ratio of the continuously variable transmission mechanism is controlled to be in a predetermined gear ratio range in which mechanical losses are less than a predetermined threshold.

2. The vehicle according to claim 1, characterized in that the predetermined gear ratio region is a gear ratio region that includes a gear ratio in which the belt gear ratio γ is 1.

3. The vehicle according to claim 1 or 2, characterized in that, in the electric motor driving mode, the belt gear ratio is controlled to the predetermined gear ratio range only within a predetermined vehicle speed range.

4. The aforementioned predetermined vehicle speed range has a lower limit and an upper limit. At vehicle speeds lower than the aforementioned lower limit, the belt gear ratio is controlled to the low side. The vehicle according to claim 3, characterized in that, at vehicle speeds higher than the aforementioned upper limit, the belt gear ratio is controlled to suppress the rotational speed of the primary pulley to a predetermined value or less.

5. The vehicle according to claim 1 or 2, characterized in that when transitioning from the electric motor driving mode to a vehicle stopping state, control is performed to return the belt gear ratio to the low side.

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