Transmission control device, transmission control method, and program

Abstract

To reduce incongruity imparted to a driver by a change of deceleration associated with a gear change of a transmission.SOLUTION: In a control device of a transmission for controlling the transmission to which a drive force of a first drive source and a drive force of a second drive source are inputted from different input shafts, the transmission comprises a gear change mechanism having at least an n-stage, an n+1 stage and an n+2 stage as gear change stages; when transmitting the drive force from the first drive source, a gear change ratio of the n+1 stage in the gear change mechanism is lower than a gear change ratio of the n-stage, and higher than a gear change ratio of the n+2 stage; when transmitting the drive force from the second drive source, the gear change ratio of the n+1 stage is lower than the gear change ratio of the n-stage, and lower than the n+2 stage; and when the first drive source and the second drive source are in states where they can transmit the drive forces to drive wheels via the gear change mechanism, respectively, and also when performing a down-shift for lowering the gear change stage from the n+2 stage, the n+1 stage is gear-changed to the n-stage without through the n+1 stage from the n+2 stage.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a transmission control device, a transmission control method, and a program. [Background technology]

[0002] Patent Document 1 discloses a gear change control device that permits shifting of the automatic transmission when it is predicted that the rotational speed of the motor generator after a predetermined time will be equal to or higher than the clutch engagement allowable rotational speed and the required deceleration after the predetermined time is predicted to be greater than the achievable deceleration after the predetermined time by a predetermined threshold or more, and that prohibits shifting of the automatic transmission during regenerative braking using the motor generator in all other cases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-137138 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the gear change control device of Patent Document 1, the deceleration rate changes depending on whether gear changes in the automatic transmission are permitted or prohibited, which may cause discomfort to the driver.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the sense of discomfort felt by the driver due to changes in deceleration that accompany gear changes in the transmission. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a transmission control device that controls a transmission into which driving force from a first driving source and driving force from a second driving source are input from different input shafts, wherein the transmission includes a transmission mechanism having at least n gear stages (n is an integer greater than or equal to 1), n+1 gear stage, and n+2 gear stage, and the gear ratio of the n+1 gear stage in the transmission mechanism is smaller than the gear ratio of the n gear stage and larger than the gear ratio of the n+2 gear stage when transmitting driving force from the first driving source, and is smaller than the gear ratio of the n gear stage and smaller than the gear ratio of the n+2 gear stage when transmitting driving force from the second driving source, and when performing a downshift from the n+2 gear stage to a lower gear stage while the first driving source and the second driving source are each able to transmit driving force to driving wheels via the transmission mechanism, the transmission control device shifts from the n+2 gear stage to the n gear stage without passing through the n+1 gear stage.

[0007] Also provided are a corresponding transmission control method and program.

[0008] According to another aspect of the present invention, there is provided a transmission control device that controls a transmission to which driving force from a first drive source and driving force from a second drive source are input from different input shafts, the transmission having a transmission mechanism with at least n gears (n is an integer greater than or equal to 1), n+1 gears, and n+2 gears, the gear ratio of the n+1 gear in the transmission mechanism is smaller than the gear ratio of the n gear and larger than the gear ratio of the n+2 gear when transmitting driving force from the first drive source, and is smaller than the gear ratio of the n gear and smaller than the gear ratio of the n+2 gear when transmitting driving force from the second drive source, and when a vehicle to which the transmission is applied is decelerating during coasting and in a state in which the first drive source and the second drive source can each transmit driving force to drive wheels via the transmission mechanism, the braking force at the n+1 gear is increased.

[0009] Also provided are a corresponding transmission control method and program. [Effects of the Invention]

[0010] In the above aspect, it is possible to reduce the discomfort felt by the driver due to the change in deceleration caused by the gear shift of the transmission. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a vehicle to which a control device for a transmission according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a diagram showing the meshing relationship of each gear in the speed change mechanism. [Figure 3] FIG. 3 is a block diagram showing the controller and the main components connected to the controller. [Figure 4] FIG. 4 is a diagram illustrating engagement of the clutch and brake in each driving mode. [Figure 5] FIG. 5 is a collinear diagram illustrating the EV mode. [Figure 6] FIG. 6 is a collinear diagram illustrating the HEV mode. [Figure 7] FIG. 7 is a diagram illustrating the relationship between the rotation speed of the electric motor and the torque of the output shaft. [Figure 8] FIG. 8 is a flowchart illustrating the gear shift control during deceleration. [Figure 9] FIG. 9 is a timing chart illustrating the speed change control during deceleration according to the comparative example. [Figure 10] FIG. 10 is a timing chart illustrating the speed change control during deceleration. [Figure 11] FIG. 11 is a flowchart illustrating the speed change control during deceleration according to the modified example. [Figure 12] FIG. 12 is a timing chart illustrating the speed change control during deceleration according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] A transmission control device and a transmission control method according to an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described below with reference to the accompanying drawings. In the following, a large gear ratio (reduction ratio) will be referred to as Low, and a small gear ratio (reduction ratio) will be referred to as High. Furthermore, a change in the gear ratio to the Low side will be referred to as a downshift, and a change in the gear ratio to the High side will be referred to as an upshift.

[0013] First, a vehicle 1 to which a transmission 100 according to this embodiment is applied will be described with reference to Figures 1 to 3. Figure 1 is a schematic diagram of the vehicle 1 to which the transmission 100 is applied. Figure 2 is a diagram showing the meshing relationship of each gear in a planetary gear mechanism 10. Figure 3 is a configuration block diagram showing a controller 2 and the main components connected to the controller 2.

[0014] The vehicle 1 includes an engine ENG, a starter motor SSG, a motor generator MG, a battery BAT as an electricity storage device, a transmission 100, drive wheels DW, a braking device (hereinafter also referred to as "brakes") BR, and a controller 2 (see FIG. 3). The vehicle 1 is a hybrid electric vehicle (HEV) that uses the engine ENG and the motor generator MG as drive sources. The power of the engine ENG and the power of the motor generator MG are transmitted to the drive wheels DW via the transmission 100. Each wheel, including the drive wheels DW, is provided with a brake BR that brakes the rotation of the wheel by frictional force.

[0015] The engine ENG is a first drive source that drives the drive wheels DW. The engine ENG is an internal combustion engine (ICE). An output shaft of the engine ENG is connected to a first input shaft IS1 (described later) of the transmission 100. The drive force of the engine ENG is transmitted to the drive wheels DW via the transmission 100.

[0016] The starter motor SSG is an electric motor used to start the engine ENG. When the starter motor SSG is driven by the engine ENG or when regenerative control is being performed, the starter motor SSG functions as a generator. The electric energy generated by the starter motor SSG is charged into the battery BAT.

[0017] The motor generator MG is a second drive source that drives the drive wheels DW. The motor generator MG is an electric motor that drives the drive wheels DW using at least one of the electric energy generated by the starter motor SSG and the electric energy stored in the battery BAT. The drive force of the motor generator MG is transmitted to the drive wheels DW via the transmission 100. The motor generator MG functions as a generator when driven by the engine ENG or when regenerative control is being performed. The output shaft of the motor generator MG is connected to a second input shaft IS2 (described later) of the transmission 100.

[0018] The battery BAT is formed, for example, by a lithium-ion secondary battery. A capacitor or the like may be provided as an electric storage device instead of the battery BAT. The battery BAT is charged with electric energy generated when the starter motor SSG and the motor generator MG are driven by the engine ENG, and electric energy generated when the starter motor SSG and the motor generator MG are regeneratively controlled. The battery BAT supplies electric energy for driving the starter motor SSG and the motor generator MG.

[0019] The transmission 100 changes the speed of the driving force of the engine ENG and the motor generator MG and transmits it to the drive wheels DW. The transmission 100 has a planetary gear mechanism 10 as a transmission mechanism, a first input shaft IS1, a second input shaft IS2, and an output shaft OS. The driving force of the engine ENG is input to the transmission 100 through the first input shaft IS1, and the driving force of the motor generator MG is input to the transmission 100 through the second input shaft IS2. In other words, the driving force of the engine ENG and the driving force of the motor generator MG are input to the transmission 100 through different input shafts.

[0020] Planetary gear mechanism 10 has, as rotating elements, a first sun gear S1, a first pinion gear P1, a first ring gear R1, a second sun gear S2, a second pinion gear P2, a second ring gear R2, and a planetary carrier (hereinafter simply referred to as "carrier") C. Planetary gear mechanism 10 has at least n-th gear (n is an integer of 1 or more), n+1-th gear, and n+2-th gear as gear stages.

[0021] The carrier C rotatably supports a first pinion gear P1. The first pinion gear P1 meshes with both the first sun gear S1 and the first ring gear R1. The carrier C also rotatably supports a second pinion gear P2. The second pinion gear P2 meshes with both the second sun gear S2, which is axially adjacent to the first sun gear S1, and the second ring gear R2, which is axially adjacent to the first ring gear R1. The first pinion gear P1 is formed by a long pinion and also meshes with the second pinion gear P2. As shown in FIG. 2, the first pinion gear P1 and the second pinion gear P2 are arranged adjacent to each other in the circumferential direction and mesh with each other.

[0022] Planetary gear mechanism 10 functions as a single-pinion planetary gear mechanism between first sun gear S1 and first ring gear R1 and between second sun gear S2 and second ring gear R2. Planetary gear mechanism 10 functions as a double-pinion planetary gear mechanism between first sun gear S1 and second ring gear R2. Planetary gear mechanism 10 uses carrier C as an output element and transmits power from at least one of engine ENG and motor generator MG to drive wheels DW via output shaft OS.

[0023] The transmission 100 has, as engagement elements, a first clutch CL1, a second clutch CL2, a first brake B1, and a second brake B2.

[0024] The first clutch CL1 selectively connects and disconnects the first input shaft IS1 and the second ring gear R2. The second clutch CL2 selectively connects and disconnects the first input shaft IS1 and the first ring gear R1. The first brake B1 selectively fixes the second ring gear R2 to a case 11, which is a fixed member of the transmission 100. The second brake B2 selectively fixes the first sun gear S1 to the case 11 of the transmission 100. The first clutch CL1, the second clutch CL2, the first brake B1, and the second brake B2 are hydraulic engagement elements that are supplied with oil from a hydraulic control circuit 30 (see FIG. 3), which will be described later, and are switched between engagement and release.

[0025] The controller 2 is configured by a microcomputer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interfaces (I / O interfaces) 21, 22 (see FIG. 3). The controller 2 can also be configured by a plurality of microcomputers. Specifically, the controller 2 can also be configured by an ATCU (automatic transmission control unit) that controls the transmission 100, an SCU (shift control unit) that controls the shift range, an ECU (engine control unit) that controls the engine ENG, and the like. The controller 2 controls the motor generator MG, the starter motor SSG, the hydraulic control circuit 30, the engine ENG, and the brake BR based on signals output from various sensors 3, etc.

[0026] The various sensors 3 are sensors that detect various parameters and include an accelerator opening detection sensor 31 that detects an accelerator opening (i.e., an acceleration request by the driver), a brake state detection sensor 32 that detects the state of an actuator that actuates the brake BR, a first rotation speed detection sensor 33 that detects the rotation speed of the starter motor SSG, a second rotation speed detection sensor 34 that detects the rotation speed of the motor generator MG, a battery voltage sensor 35 that detects the voltage value of the battery BAT, and a vehicle speed sensor 36 that detects the speed of the vehicle 1.

[0027] 3, the controller 2 includes an input interface 21, an output interface 22, a memory unit 23, a starter motor control unit 24, a motor generator control unit 25, a hydraulic control circuit control unit (hereinafter simply referred to as the "circuit control unit") 26, a determination unit 27, an engine control unit 28, and a service brake control unit (hereinafter simply referred to as the "brake control unit") 29, all of which are electrically connected to one another. The starter motor control unit 24, the motor generator control unit 25, the circuit control unit 26, the determination unit 27, the engine control unit 28, and the brake control unit 29 are virtual units that represent the functions of the controller 2 for controlling the vehicle 1, and do not represent physical entities.

[0028] The input interface 21 receives output signals from the various sensors 3 .

[0029] The storage unit 23 is a memory for temporarily storing output signals from the various sensors 3. The storage unit 23 also stores processing programs and algorithm programs executed in the starter motor control unit 24, the motor generator control unit 25, the circuit control unit 26, the determination unit 27, the engine control unit 28, and the brake control unit 29. In this embodiment, the storage unit 23 is built into the controller 2, but is not limited to this and may be provided separately from the controller 2, for example.

[0030] The starter motor control command generated by processing in the starter motor control unit 24, the motor generator control command generated by processing in the motor generator control unit 25, the circuit control command generated by processing in the circuit control unit 26, the engine control command generated by processing in the engine control unit 28, and the brake control command generated by processing in the brake control unit 29 are output via the output interface 22 to the starter motor SSG, the motor generator MG, the hydraulic control circuit 30, the engine ENG, and the brake BR, respectively.

[0031] The starter motor control unit 24 generates a starter motor control command based on the output signals output from the various sensors 3, and outputs the generated starter motor control command to the starter motor SSG via the output interface 22.

[0032] The motor generator control unit 25 generates a motor generator control command based on the output signals output from the various sensors 3, and outputs the generated motor generator control command to the motor generator MG via the output interface 22.

[0033] The circuit control unit 26 generates a circuit control command based on the output signals output from the various sensors 3, and outputs the generated circuit control command to the hydraulic control circuit 30 via the output interface 22. The circuit control unit 26 has a clutch control module 261 and a brake control module 262.

[0034] The clutch control module 261 generates a clutch control command based on output signals output from the various sensors 3, and outputs the generated clutch control command to the hydraulic control circuit 30 via the output interface 22. Upon receiving a supply of oil from the hydraulic control circuit 30, the first clutch CL1 and the second clutch CL2 are switched between engagement and release.

[0035] The brake control module 262 generates a brake control command based on output signals output from the various sensors 3, and outputs the generated brake control command to the hydraulic control circuit 30 via the output interface 22. Oil is supplied from the hydraulic control circuit 30, and the first brake B1 and the second brake B2 are switched between engagement and release.

[0036] The judgment unit 27 makes various judgments based on the output signals output from the various sensors 3, and outputs the results of the various judgments to the starter motor control unit 24, the motor generator control unit 25, the circuit control unit 26, the judgment unit 27, the engine control unit 28, or the brake control unit 29.

[0037] The engine control unit 28 generates an engine control command based on the output signals output from the various sensors 3, and outputs the generated engine control command to the engine ENG via the output interface 22.

[0038] The brake control unit 29 generates a brake control command based on the output signals output from the various sensors 3, and outputs the generated brake control command to the brake BR via the output interface 22.

[0039] Next, each driving mode of the vehicle 1 will be described with reference to Fig. 4. Fig. 4 is a diagram illustrating the engagement and release of the first clutch CL1, the second clutch CL2, the first brake B1, and the second brake B2 in each driving mode. In Fig. 4, "◯" indicates that the engagement element is in an engaged state, and a blank space indicates that the engagement element is in a released state.

[0040] The vehicle 1 has an EV (Electric Vehicle) mode, which is a motor driving mode in which the vehicle runs using only the driving force of the motor generator MG out of the engine ENG and the motor generator MG, and an HEV (Hybrid Electric Vehicle) mode in which the vehicle runs using the driving force of the engine ENG and the driving force of the motor generator MG.

[0041] The EV mode has an EV 1st speed (EV 1st) and an EV 2nd speed (EV 2nd).

[0042] In EV1, only the first brake B1 is engaged, and the first clutch CL1, second clutch CL2, and second brake B2 are not engaged. In EV2, only the second brake B2 is engaged, and the first clutch CL1, second clutch CL2, and first brake B1 are not engaged.

[0043] The HEV mode has HEV 1st gear (HEV 1st), HEV 2nd gear (HEV 2nd), HEV 3rd gear (HEV 3rd), and HEV 4th gear (HEV 4th). Note that 1st gear, 2nd gear, 3rd gear, and 4th gear indicate the respective gear stages of the transmission 100.

[0044] In the HEV first gear, the second clutch CL2 and the first brake B1 are engaged, and the first clutch CL1 and the second brake B2 are not engaged. In the HEV first gear, the second clutch CL2 and the first brake B1 are fully engaged. The second clutch CL2 and the first brake B1 constitute the clutches that are engaged when the vehicle starts.

[0045] In the first gear of the HEV, WSC control (wet start clutch control) is performed by slipping the second clutch CL2 and engaging the first brake B1. WSC control is slip control performed when the vehicle starts moving. In WSC control, the second clutch pressure, which is the hydraulic oil pressure of the second clutch CL2, is set to an engagement pressure lower than the full engagement pressure, so that the second clutch CL2 is gradually engaged while slipping. The engagement pressure is set to gradually increase over time. The full engagement pressure and the engagement pressure are set in advance.

[0046] In HEV second gear, the second clutch CL2 and second brake B2 are engaged, and the first clutch CL1 and first brake B1 are not engaged. In HEV third gear, the first clutch CL1 and second clutch CL2 are engaged, and the first brake B1 and second brake B2 are not engaged. HEV third gear is a so-called direct-coupled state in which the gear ratio of the transmission 100 is 1. In HEV fourth gear, the first clutch CL1 and second brake B2 are engaged, and the second clutch CL2 and first brake B1 are not engaged.

[0047] The vehicle 1 moves backward by driving the motor generator MG in reverse rotation in EV1 or EV2. The transmission 100 is placed in a neutral state by releasing all of the first clutch CL1, the second clutch CL2, the first brake B1, and the second brake B2.

[0048] Next, each driving mode of the vehicle 1 will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is a collinear diagram illustrating the EV mode. Fig. 6 is a collinear diagram illustrating the HEV mode. Fig. 7 is a diagram illustrating the relationship between the rotation speed of the motor generator MG and the torque of the output shaft OS.

[0049] As shown in Figures 5 and 6, in the nomographic diagram, each rotating element is arranged on the horizontal axis with an axis-to-axis distance corresponding to the gear ratio, and the vertical axis represents the rotational speed of each rotating element. In the nomographic diagram, the relationship between each rotating element due to gear meshing is represented by a rigid lever connecting each rotating element with a straight line, and gear changes in transmission 100 are represented by the rotational movement of the rigid lever. Transmission 100 is configured so that five rotating elements are arranged on the horizontal axis of the nomographic diagram, in order from the first rotating element to the second rotating element, the third rotating element, the fourth rotating element, and the fifth rotating element, at intervals corresponding to the gear ratio. In transmission 100, the five rotating elements are a first sun gear S1, a second ring gear R2, a carrier C, a first ring gear R1, and a second sun gear S2.

[0050] As shown in Fig. 5, in EV1 gear, the relationship between the rotating elements is such that the second ring gear R2 is connected to the case 11 by the first brake B1. Therefore, the EV1 gear is represented by a rigid lever that swings around the first brake B1 on the second ring gear R2 in response to changes in the rotational speed of the second sun gear S2 (the rotational speed of the motor generator MG).

[0051] In EV2 gear, the relationship between the rotating elements is such that first sun gear S1 is connected to case 11 by second brake B2. Therefore, EV2 gear is represented by a rigid lever that swings around second brake B2 on first sun gear S1 in response to changes in the rotational speed of second sun gear S2 (rotational speed of motor generator MG).

[0052] Thus, in EV1 speed and EV2 speed, the rotation speed of the output shaft OS changes depending on the rotation speed of the motor generator MG. In EV1 speed, the gear ratio (reduction ratio) is larger than in EV2 speed when the rotation speed of the motor generator MG is the same. In other words, EV1 speed is a low-side motor driving mode with a larger gear ratio (reduction ratio) than in EV2 speed, and EV2 speed is a high-side motor driving mode with a smaller gear ratio (reduction ratio) than in EV1 speed.

[0053] As shown in Fig. 6, in HEV first gear, the relationship between the rotating elements is such that the first ring gear R1 is connected to the first input shaft IS1 by the second clutch CL2, and the second ring gear R2 is connected to the case 11 by the first brake B1. Therefore, HEV first gear is represented by a rigid lever that connects the second clutch CL2 on the first ring gear R1 and the first brake B1 on the second ring gear R2 with a straight line.

[0054] In HEV second gear, the relationship between the rotating elements is such that the first ring gear R1 is connected to the first input shaft IS1 by the second clutch CL2, and the first sun gear S1 is connected to the case 11 by the second brake B2. Therefore, HEV second gear is represented by a rigid lever that connects the second clutch CL2 on the first ring gear R1 and the second brake B2 on the first sun gear S1 with a straight line.

[0055] In HEV 3rd gear, the relationship between the rotating elements is such that the first ring gear R1 is connected to the first input shaft IS1 by the second clutch CL2, and the second ring gear R2 is connected to the first input shaft IS1 by the first clutch CL1. Therefore, HEV 3rd gear is represented by a rigid lever that connects the second clutch CL2 on the first ring gear R1 and the first clutch CL1 on the second ring gear R2 with a straight line.

[0056] In the HEV 4th gear, the relationship between the rotating elements is such that the second ring gear R2 is connected to the first input shaft IS1 by the first clutch CL1, and the first sun gear S1 is connected to the case 11 by the second brake B2. Therefore, the HEV 4th gear is represented by a rigid lever that connects the first clutch CL1 on the second ring gear R2 and the second brake B2 on the first sun gear S1 with a straight line.

[0057] When shifting from HEV 1st gear to HEV 2nd gear, the first brake B1 is released and the second brake B2 is engaged while the second clutch CL2 remains engaged. That is, the rigid lever rotates around the second clutch CL2 on the first ring gear R1. When shifting from HEV 2nd gear to HEV 3rd gear, the second clutch CL2 remains engaged while the second brake B2 is released and the first clutch CL1 is engaged. That is, the rigid lever rotates around the second clutch CL2 on the first ring gear R1. When shifting from HEV 3rd gear to HEV 4th gear, the first clutch CL1 remains engaged while the second clutch CL2 is released and the second brake B2 is engaged. That is, the rigid lever rotates around the first clutch CL1 on the second ring gear R2.

[0058] When transmitting driving force from the engine ENG, HEV 1st gear is the gear with the largest gear ratio, HEV 2nd gear is the gear with a smaller gear ratio than HEV 1st gear and a larger gear ratio than HEV 3rd gear, HEV 3rd gear is the gear with a smaller gear ratio than HEV 2nd gear and a larger gear ratio than HEV 4th gear, and HEV 4th gear is the gear with the smallest gear ratio.

[0059] On the other hand, when transmitting driving force from the motor generator MG, HEV 1st gear is the gear with the largest gear ratio, HEV 2nd gear is a gear with a smaller gear ratio than HEV 1st gear and a larger gear ratio than HEV 3rd gear, HEV 3rd gear is a gear with a smaller gear ratio than HEV 2nd gear and a smaller gear ratio than HEV 4th gear, and HEV 4th gear is not the gear with the smallest gear ratio, but has the same gear ratio as HEV 2nd gear.

[0060] That is, if the HEV 2nd gear in transmission 100 is n-th gear (n is an integer equal to or greater than 1), the HEV 3rd gear is n+1-th gear, and the HEV 4th gear is n+2-th gear, when transmitting driving force from the engine ENG, the gear ratio of the n+1th gear is smaller than the gear ratio of the nth gear and larger than the gear ratio of the n+2th gear. On the other hand, when transmitting driving force from the motor generator MG, the gear ratio of the n+1th gear is smaller than the gear ratio of the nth gear and smaller than the gear ratio of the n+2th gear.

[0061] 7, in transmission 100, when viewed from second input shaft IS2 of motor generator MG, a downshift from HEV 4th gear to HEV 3rd gear reduces the gear ratio and the torque of output shaft OS. In other words, despite a downshift to a lower gear, a reverse phenomenon occurs in which the gear ratio decreases as if an upshift to a higher gear were performed.

[0062] Here, if the state of charge (SOC) of the battery BAT is within an appropriate range, the first clutch CL1 and the second clutch CL2 are released and the engine ENG is disconnected when decelerating the vehicle 1. This prevents the engine ENG from being rotated by the rotation of the drive wheels DW, maximizing the amount of regeneration by the motor generator MG.

[0063] However, if the engine ENG is disconnected, when the driver presses the accelerator pedal again, the amount of power consumed increases due to the assistance from the motor generator MG and the restart of the engine ENG by the starter motor SSG. Therefore, when the SOC of the battery BAT is extremely low (lower than the threshold SOC1), regeneration is performed by the motor generator MG while the engine ENG is connected in order to suppress power consumption.

[0064] As described above, when transmission 100 downshifts from HEV 4th gear to HEV 3rd gear as viewed from second input shaft IS2 of motor generator MG, a reverse rotation phenomenon occurs in which the gear ratio becomes smaller as if an upshift had been performed to a higher gear, despite the downshift having been performed to a lower gear. This can cause the required deceleration to be insufficient, which can be uncomfortable for the driver. Therefore, transmission 100 performs the following control to reduce this uncomfortable feeling for the driver.

[0065] Next, referring to FIG. 8, the gear shift control during deceleration of the vehicle 1 will be described. FIG. 8 is a flowchart illustrating the gear shift control during deceleration. The gear shift control during deceleration is performed by repeatedly executing the flow of FIG. 8 at regular intervals by the controller 2. The flow of FIG. 8 is executed when the driver requests deceleration of the vehicle 1. Specifically, for example, the flow is executed when the driver has released the accelerator pedal, that is, when the vehicle 1 is decelerating while coasting (a state in which the engine ENG and motor generator MG, which are drive sources, are running without outputting drive force). At this time, the driver may operate the brake pedal to perform regenerative control (regenerative braking) by the motor generator MG. Note that when the one-pedal mode is selected, regenerative control (regenerative braking) by the motor generator MG is performed not only when the accelerator pedal is released but also when the accelerator pedal operation amount becomes small. In this way, the presence of a deceleration request is determined based on the driving state, such as the speed, of the vehicle 1 and the driver's operation.

[0066] In step S11, the controller 2 determines whether the SOC of the battery BAT is extremely low. Specifically, the controller 2 estimates the SOC of the battery BAT from the voltage value of the battery BAT detected by the battery voltage sensor 35, and determines whether the estimated SOC is lower than a predetermined (threshold SOC1). The threshold SOC1 is preset to the minimum SOC value capable of supplying power for the assist by the motor generator MG and the restart of the engine ENG by the starter motor SSG when the driver steps on the accelerator pedal again, and is stored in the storage unit 23.

[0067] If it is determined in step S11 that the SOC is less than the threshold SOC1 (SOC < SOC1), the process proceeds to step S12. On the other hand, if it is determined in step S11 that the SOC is not less than the threshold SOC1, that is, the SOC is greater than or equal to the threshold SOC1 (SOC ≧ SOC1), the process proceeds to step S17.

[0068] In step S12, since the SOC of the battery BAT is extremely low, a HEV (Hybrid Electric Vehicle) priority mode in which the engine ENG is not disconnected is selected, and regeneration is performed by the motor generator MG while the engine ENG is connected. That is, the transmission 100 maintains a state in which the engine ENG and the motor generator MG can each transmit driving force to the drive wheels DW via the planetary gear mechanism 10.

[0069] In step S13, the controller 2 determines whether the one-pedal mode is selected. The one-pedal mode is a driving mode in which the driver controls the vehicle speed by operating only the accelerator pedal. That is, in the one-pedal mode, the deceleration of the vehicle 1 when the operation amount of the accelerator pedal becomes small is greater than the deceleration when not in the one-pedal mode.

[0070] If it is determined in step S13 that the one-pedal mode is selected, the required deceleration is likely to be equal to or greater than the maximum speed of HEV 3rd gear, so the process proceeds to step S16. On the other hand, if it is determined in step S13 that the one-pedal mode is not selected, the process proceeds to step S14.

[0071] In step S14, it is determined whether the vehicle 1 is running in HEV 4th gear. If it is determined in step S14 that the vehicle 1 is running in HEV 4th gear, the process proceeds to step S15. On the other hand, if it is determined in step S14 that the vehicle 1 is not running in HEV 4th gear, the process proceeds to step S17.

[0072] In step S15, it is determined whether the required deceleration of vehicle 1 is equal to or greater than the maximum speed of HEV 3rd gear. If it is determined in step S15 that the required deceleration of vehicle 1 is equal to or greater than the maximum speed of HEV 3rd gear, the process proceeds to step S16. On the other hand, if it is determined in step S15 that the required deceleration of vehicle 1 is not equal to or greater than the maximum speed of HEV 3rd gear, the process proceeds to step S17.

[0073] In step S16, controller 2 prohibits a shift from HEV 4 to HEV 3 during coasting, and shifts from HEV 4 to HEV 2 without passing through HEV 3. That is, when downshifting from n+2 to a lower gear, transmission 100 shifts from n+2 to n without passing through n+1.

[0074] On the other hand, in step S17, the controller 2 performs a normal gear shift because the required deceleration of the vehicle 1 is relatively small. That is, the controller 2 performs a gear shift from HEV 4th gear to HEV 3rd gear, and if the vehicle is further decelerated, performs a gear shift from HEV 3rd gear to HEV 2nd gear.

[0075] Next, the gear shift control during deceleration in the vehicle 1 will be specifically described with reference to Fig. 9 and Fig. 10. Fig. 9 is a timing chart illustrating the gear shift control during deceleration according to a comparative example. Fig. 10 is a timing chart illustrating the gear shift control during deceleration.

[0076] First, a comparative example will be described with reference to Fig. 9. This comparative example shows a case where, when it is determined that the required deceleration of the vehicle 1 is equal to or greater than the maximum speed of HEV 3rd gear, normal gear shifting is performed in step S17 instead of the processing in step S16 in Fig. 8.

[0077] As shown in FIG. 9, at time T1, it is determined that a deceleration request has been made by the driver. Here, an example will be described in which the deceleration request is made by releasing the accelerator pedal. When the accelerator pedal is released, the vehicle 1 starts coasting. Once coasting begins, the deceleration of the vehicle 1 increases over time toward the requested deceleration, and the speed of the vehicle 1 also decreases over time. At time T2, the deceleration reaches the requested deceleration and becomes constant, but the speed of the vehicle 1 continues to decrease over time.

[0078] At time T3, the speed of vehicle 1 falls below the predetermined vehicle speed for downshifting from HEV 4th gear, so a downshift is performed to lower the gear from HEV 4th gear to HEV 3rd gear. Also, at time T4, the speed of vehicle 1 falls below the predetermined vehicle speed for downshifting from HEV 3rd gear, so a downshift is performed to lower the gear from HEV 3rd gear to HEV 2nd gear.

[0079] As described above, when transmission 100 downshifts from HEV 4 to HEV 3 as viewed from second input shaft IS2 of motor / generator MG, a reversal phenomenon occurs in which the gear ratio decreases as if an upshift were performed to increase the gear, despite the downshift being a lower gear. Therefore, unless the regenerative torque is increased between the time when the downshift is performed from HEV 4 to HEV 3 and the time when the downshift is performed from HEV 3 to HEV 2, the deceleration will be less than the required deceleration. As such, the change in deceleration accompanying the gear shift of transmission 100 may cause discomfort to the driver.

[0080] In contrast, as shown in Figure 10, at time T3, the speed of the vehicle 1 falls below the predetermined vehicle speed for downshifting from HEV 4 and the required deceleration is greater than the maximum speed in HEV 3. Therefore, a downshift is performed to lower the gear from HEV 4 to HEV 2 without passing through HEV 3. This prevents a decrease in deceleration due to a downshift from HEV 4 to HEV 3. This reduces the discomfort felt by the driver due to a change in deceleration accompanying a gear change in transmission 100.

[0081] In this way, during coasting in which the engine ENG and the motor generator MG are rotated by the drive wheels DW via the transmission 100, if the speed of the vehicle 1 to which the transmission 100 is applied drops below a predetermined vehicle speed and a downshift is performed to lower the gear from n+2, and if the required deceleration of the vehicle 1 is greater than the maximum deceleration of n+1, the gear is shifted from n+2 to n without passing through n+1. This makes it possible to prevent a decrease in deceleration caused by downshifting from n+2 to n+1. This makes it possible to reduce the discomfort felt by the driver due to a change in deceleration accompanying a gear change in the transmission 100.

[0082] Next, a shift control during deceleration according to a modified example will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a flowchart illustrating the shift control during deceleration according to a modified example. Fig. 12 is a timing chart illustrating the shift control during deceleration according to a modified example.

[0083] In this modification, the controller 2 executes the process of step S26 instead of step S16 in FIG.

[0084] In step S26 of Figure 11, controller 2 does not prohibit a shift from HEV 4th gear to HEV 3rd gear during coasting, but increases the braking force in HEV 3rd gear. That is, when vehicle 1 to which transmission 100 is applied is decelerating during coasting, and a downshift is performed to lower the gear from n+2 to n+1 while engine ENG and motor generator MG are both able to transmit driving force to drive wheels DW via planetary gear mechanism 10, the braking force in n+1 gear is increased. This increase in braking force is achieved by increasing the amount of regeneration of motor generator MG, by operating brake BR, or by both of these.

[0085] As a result, as shown in Figure 12, at time T3, the speed of vehicle 1 falls below the predetermined vehicle speed for downshifting from HEV 4th gear, so a downshift is performed to lower the gear from HEV 4th gear to HEV 3rd gear.However, since the deceleration rate decreases due to the smaller gear ratio, the braking force is increased to offset the decrease in deceleration, and vehicle 1 continues to decelerate at a constant deceleration rate.

[0086] That is, when HEV 2nd gear in transmission 100 is nth gear (n is an integer greater than or equal to 1), HEV 3rd gear is n+1th gear, and HEV 4th gear is n+2th gear, when transmitting driving force from the motor generator MG, downshifting from n+2th gear to n+1th gear reduces the gear ratio, so this is offset by increasing the braking force accordingly. This makes it possible to prevent a decrease in deceleration caused by downshifting from n+2th gear to n+1th gear. This makes it possible to reduce the sense of discomfort felt by the driver by changes in deceleration accompanying gear changes in transmission 100.

[0087] The configuration and effects of the present embodiment will now be described.

[0088] (1) (7) (9) In a transmission control device that controls a transmission 100 to which the driving force of a first driving source (engine ENG) and the driving force of a second driving source (motor generator MG) are input from different input shafts (IS1, IS2), the transmission 100 is provided with a transmission mechanism (planetary gear mechanism 10) having at least n-stages (n is an integer of 1 or more), n+1-stages, and n+2-stages as gear ratios, and the gear ratio of the n+1-stage in the transmission mechanism (planetary gear mechanism 10) is set to When transmitting driving force from the second drive source (motor generator MG), the gear ratio is smaller than the gear ratio of n stage and larger than the gear ratio of n+2 stage, and when transmitting driving force from the second drive source (motor generator MG), the gear ratio is smaller than the gear ratio of n stage and smaller than the gear ratio of n+2 stage, and when downshifting from n+2 stage to a lower gear stage in a state in which the first drive source (engine ENG) and the second drive source (motor generator MG) can transmit driving force to the drive wheels DW via the transmission mechanism (planetary gear mechanism 10), the gear is shifted from n+2 stage to n stage without passing through n+1 stage.

[0089] In this configuration, the gear ratio of the n+1 gear is smaller than the gear ratio of the n gear and larger than the gear ratio of the n+2 gear when transmitting driving force from the engine ENG, and is smaller than the gear ratio of the n gear and smaller than the gear ratio of the n+2 gear when transmitting driving force from the motor-generator MG. Therefore, when transmitting driving force from the motor-generator MG, downshifting from the n+2 gear to the n+1 gear reduces the gear ratio, so the gear ratio is increased by downshifting from the n+2 gear to the n gear without passing through the n+1 gear. This prevents a decrease in deceleration caused by downshifting from the n+2 gear to the n+1 gear. This reduces the sense of discomfort felt by the driver due to changes in deceleration accompanying shifts in the transmission 100.

[0090] In particular, when a motor generator MG with a low maximum regenerative torque is used, the decrease in deceleration caused by downshifting from n+2 to n+1 may not be absorbed even if the regenerative torque of the motor generator MG is maximized. In contrast, transmission 100 downshifts from n+2 to n without passing through n+1, thereby preventing a decrease in deceleration even when a motor generator MG with a low maximum regenerative torque is used. Furthermore, since there is no need to apply braking with the brake BR to prevent a decrease in deceleration, a decrease in energy that can be recovered by regenerative control can be prevented.

[0091] (2) The first drive source is an engine ENG as an internal combustion engine, and the second drive source is a motor generator MG as an electric motor.

[0092] According to this configuration, it is possible to suppress changes in deceleration due to the reversal of the gear ratio during downshifting while obtaining regenerative power from the motor generator MG, thereby reducing the sense of discomfort felt by the driver.

[0093] (3) Furthermore, when the vehicle 1 to which the transmission 100 is applied is decelerating while coasting, and the engine ENG and the motor generator MG are each capable of transmitting driving force to the drive wheels DW via the planetary gear mechanism 10, if a downshift is performed from the n+2 gear to a lower gear, the gear is shifted from the n+2 gear to the n+1 gear without passing through the n+1 gear.

[0094] According to this configuration, the change in deceleration caused by the reversal of the speed ratio when downshifting during coasting can be suppressed, thereby reducing the sense of discomfort felt by the driver.

[0095] (4) Furthermore, the vehicle 1 to which the transmission 100 is applied has a battery BAT, and when the SOC of the battery BAT is lower than a predetermined value, the engine ENG and the motor generator MG are each in a coasting state in which they are rotated by the drive wheels DW via the transmission 100, and when the speed of the vehicle 1 falls below a predetermined vehicle speed and a downshift is performed from n+2 gear to a lower gear, the gear is shifted from n+2 gear to n gear without passing through n+1 gear.

[0096] With this configuration, even if the SOC of the battery BAT is low, the engine ENG is rotated by the rotation of the drive wheels DW, so there is no need to restart the engine ENG even if there is a request for re-acceleration.In addition, since the battery BAT is charged with regenerative power from the motor generator MG, changes in deceleration due to the reversal of the gear ratio during downshifting can be suppressed, thereby reducing the discomfort felt by the driver.

[0097] (5) Also, during coasting in which the engine ENG and the motor generator MG are each rotated by the drive wheels DW via the transmission 100, if the speed of the vehicle 1 to which the transmission 100 is applied falls below a predetermined vehicle speed and a downshift is performed to lower the gear from n+2, if the required deceleration of the vehicle 1 is greater than the maximum deceleration of n+1, the gear will be shifted from n+2 to n without passing through n+1.

[0098] According to this configuration, when the required deceleration is greater than the maximum deceleration of the n+1 gear, the gear is shifted from the n+2 gear to the n gear without passing through the n+1 gear, thereby preventing the driver from feeling uncomfortable due to a decrease in deceleration despite having downshifted.

[0099] (6) (8) (10) In addition, in a transmission control device that controls a transmission 100 to which the driving force of a first driving source (engine ENG) and the driving force of a second driving source (motor generator MG) are input from different input shafts (IS1, IS2), the transmission 100 is provided with a transmission mechanism (planetary gear mechanism 10) having at least n-stage (n is an integer of 1 or more), n+1-stage, and n+2-stage as gear ratios, and the gear ratio of the n+1-stage in the transmission mechanism (planetary gear mechanism 10) is set to be smaller than the gear ratio of the n-stage when transmitting the driving force from the first driving source (engine ENG). and is greater than the gear ratio of the n+2 stage, and when transmitting driving force from the second driving source (motor generator MG), it is smaller than the gear ratio of the n stage and is smaller than the gear ratio of the n+2 stage, and when the vehicle 1 to which the transmission 100 is applied is decelerating during coasting, the first driving source (engine ENG) and the second driving source (motor generator MG) can each transmit driving force to the driving wheels DW via the transmission mechanism (planetary gear mechanism 10), and when a downshift is performed to lower the gear from n+2 stage to n+1 stage, the braking force at n+1 stage is increased.

[0100] In this configuration, the gear ratio of the n+1th gear is smaller than the gear ratio of the nth gear and larger than the gear ratio of the n+2th gear when transmitting driving force from the engine ENG, and is smaller than the gear ratio of the nth gear and smaller than the gear ratio of the n+2th gear when transmitting driving force from the motor-generator MG. Therefore, when transmitting driving force from the motor-generator MG, downshifting from the n+2th gear to the n+1th gear reduces the gear ratio, so the braking force at the n+1th gear is increased. This prevents a decrease in deceleration caused by downshifting from the n+2th gear to the n+1th gear. This reduces the sense of discomfort felt by the driver due to changes in deceleration accompanying shifts in the transmission 100.

[0101] Although an embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0102] For example, in the above embodiment, a case where a downshift (coast down) is performed during coasting has been described. However, the present invention is not limited to this. The shift control of the above embodiment may also be applied to a downshift during kickdown when the driver depresses the accelerator pedal to accelerate. When applied to a downshift during kickdown, if the required acceleration of the vehicle 1 is greater than the maximum acceleration of HEV 3rd gear, the shift is made from HEV 4th gear to HEV 2nd gear without passing through HEV 3rd gear. This reduces the discomfort felt by the driver due to changes in acceleration accompanying the shift of the transmission 100.

[0103] Furthermore, in the above embodiment, the transmission 100 has four speed stages from HEV 1st speed to HEV 4th speed, but it is sufficient that the transmission has at least three speed stages.

[0104] The series of processes in the transmission 100 described above may be provided as a program for execution by a computer.

[0105] In other words, the program of this embodiment causes the computer to execute a procedure for increasing the braking force at n+1 gear when a downshift is performed to lower the gear from n+2 to n+1 gear while the vehicle 1 to which the transmission 100 is applied is decelerating while coasting and the first driving source (engine ENG) and the second driving source (motor generator MG) are each able to transmit driving force to the drive wheels DW via the transmission mechanism (planetary gear mechanism 10), or a procedure for increasing the braking force at n+1 gear when a downshift is performed to lower the gear from n+2 to n+1 gear while the vehicle 1 to which the transmission 100 is applied is decelerating while coasting and the first driving source (engine ENG) and the second driving source (motor generator MG) are each able to transmit driving force to the drive wheels DW via the transmission mechanism (planetary gear mechanism 10).

[0106] The program for executing the above-described series of processes is provided by a computer-readable storage medium, and may be stored in the storage unit 23 of the controller 2.

[0107] Furthermore, the various programs executed by the computer may be stored in a non-transitory recording medium such as a CD-ROM. [Explanation of symbols]

[0108] 100 gears 1 vehicle 10 Planetary gear mechanism (transmission mechanism) BAT Battery (electricity storage device) BR Brake (braking device) DW drive wheel ENG Engine (first drive source, internal combustion engine) MG Motor generator (second drive source, electric motor) SSG starter motor

Claims

1. A control device for a transmission that controls a transmission to which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; When a downshift is performed from the n+2 speed to a lower gear position while the first drive source and the second drive source are each capable of transmitting drive force to the drive wheels via the transmission mechanism, the gear is shifted from the n+2 speed to the n speed without passing through the n+1 speed. Transmission control device.

2. The transmission control device according to claim 1, the first drive source is an internal combustion engine, the second drive source is an electric motor; Transmission control device.

3. The transmission control device according to claim 1 or 2, When a vehicle to which the transmission is applied is decelerating during coasting, and the first drive source and the second drive source are able to transmit drive force to the drive wheels via the transmission mechanism, if a downshift is performed from the n+2 speed to a lower speed, the transmission is shifted from the n+2 speed to the n speed without passing through the n+1 speed. Transmission control device.

4. 4. The transmission control device according to claim 1, a vehicle to which the transmission is applied has an electricity storage device, When the state of charge of the power storage device is lower than a predetermined state, the first drive source and the second drive source are each in a coasting state in which they are rotated by the drive wheels via the transmission, and when the speed of the vehicle falls below a predetermined vehicle speed and a downshift is performed from the n+2 stage to a lower gear stage, the gear is shifted from the n+2 stage to the n stage without passing through the n+1 stage. Transmission control device.

5. 4. The transmission control device according to claim 1, During coasting in which the first drive source and the second drive source are rotated by the drive wheels via the transmission, when the speed of the vehicle to which the transmission is applied falls below a predetermined vehicle speed and a downshift is performed from the n+2 gear to a lower gear, if the required deceleration of the vehicle is greater than the maximum deceleration of the n+1 gear, the gear is shifted from the n+2 gear to the n gear without passing through the n+1 gear. Transmission control device.

6. A control device for a transmission that controls a transmission to which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; When a vehicle to which the transmission is applied is decelerating during coasting, and the first drive source and the second drive source are able to transmit drive forces to the drive wheels via the transmission mechanism, if a downshift is performed to lower the gear position from the n+2 stage to the n+1 stage, the braking force at the n+1 stage is increased. Transmission control device.

7. A method for controlling a transmission in which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the method comprising: the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; When a downshift is performed from the n+2 speed to a lower gear position while the first drive source and the second drive source are each capable of transmitting drive force to the drive wheels via the transmission mechanism, the gear is shifted from the n+2 speed to the n speed without passing through the n+1 speed. Transmission control method.

8. A method for controlling a transmission in which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the method comprising: the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; When a vehicle to which the transmission is applied is decelerating during coasting, and the first drive source and the second drive source are able to transmit drive forces to the drive wheels via the transmission mechanism, if a downshift is performed to lower the gear position from the n+2 stage to the n+1 stage, the braking force at the n+1 stage is increased. Transmission control method.

9. A computer-executable program for controlling a transmission to which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; When a downshift is performed from the n+2th gear to a lower gear in a state in which the first driving source and the second driving source can transmit driving force to the driving wheels via the transmission mechanism, the computer is caused to execute a procedure of shifting from the n+2th gear to the nth gear without passing through the n+1th gear. program.

10. A computer-executable program for controlling a transmission to which a driving force of a first driving source and a driving force of a second driving source are input from different input shafts, the transmission includes a transmission mechanism having at least n speeds (n is an integer of 1 or more), n+1 speeds, and n+2 speeds as speed change speeds, a speed ratio of the n+1th stage in the transmission mechanism is smaller than a speed ratio of the nth stage and larger than a speed ratio of the n+2th stage when transmitting driving force from the first driving source, and is smaller than a speed ratio of the nth stage and smaller than a speed ratio of the n+2th stage when transmitting driving force from the second driving source; when a vehicle to which the transmission is applied is decelerating during coasting and the first drive source and the second drive source are able to transmit drive force to the drive wheels via the transmission mechanism, and a downshift is performed to lower the gear position from the n+2 gear to the n+1 gear, the computer is caused to execute a procedure of increasing the braking force at the n+1 gear. program.

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