Vehicle gear shift control method and vehicle gear shift control device

Abstract

To improve inconvenience which occurs by a temporary cut-off of power transmission, in a vehicle where power is transmitted to drive wheels from a drive motor via a transmission that goes by way of a neutral position at shifting.SOLUTION: A shift control method of a vehicle 100 includes: a motor 10; and a transmission 16 which performs power transmission between the motor 10 and a drive wheel 11, and which goes by way of a neutral position at shifting. In the control method of the vehicle 100, the transmission 16 includes an ACTR 51 which actuates according to a shift instruction. At shifting of the transmission 16, before the shift instruction to the ACTR 51 is performed, the ACTR 51 is actuated to the neutral position side.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a vehicle gear shift control. [Background technology]

[0002] Patent Document 1 discloses a four-wheel drive hybrid vehicle, in which a second transmission is provided between the motor generator and the front wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-27383 A Summary of the Invention [Problem to be solved by the invention]

[0004] When power is transmitted from the drive motor to the drive wheels via a transmission, the maximum drive force and maximum rotation speed of the drive motor can be improved by shifting. Therefore, in this case, the size of the drive motor can be suppressed. However, in the case of a transmission in which the gear shift is performed via a neutral position, the power transmission is temporarily interrupted during the gear shift. Therefore, in this case, even though the drive source is a drive motor that can generate power continuously over the entire driving range, the power transmission is temporarily interrupted during the gear shift, which may cause inconvenience such as a sense of discomfort to the driver or a decrease in driving stability.

[0005] The present invention has been made in consideration of such problems, and aims to improve the inconvenience that can arise due to a temporary interruption of power transmission in a vehicle in which power is transmitted from a drive motor to drive wheels via a transmission that passes through a neutral position when changing gears. [Means for solving the problem]

[0006] A vehicle gear shift control method according to one aspect of the present invention is used in a vehicle that includes a first drive motor and a first transmission that transmits power between the first drive motor and a first drive wheel and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command. When the engagement force of the first dog clutch, which is a shift clutch of the first transmission, is greater than the release force of the first dog clutch by the first shift actuator, When shifting gears in the first transmission, the first shift actuator is actuated toward the neutral position before a shift command is issued to the first shift actuator.

[0007] According to another aspect of the present invention, there is provided a vehicle gear shift control device corresponding to the vehicle gear shift control method described above. Effect of the Invention

[0008] According to these aspects, the shift actuator is moved to the neutral position before a gear shift command is issued, thereby shortening the gear shift time, thereby improving inconveniences such as a sense of discomfort or reduced driving stability that may occur due to a temporary interruption in power transmission. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Diagram 2] FIG. 13 is an external view of a shift mechanism without a standby spring. [Diagram 3] FIG. 4 is a front view of the periphery of the cam plate. [Figure 4] FIG. 13 is a diagram showing a schematic diagram of a shift mechanism without a standby spring. [Diagram 5] FIG. 13 is a diagram illustrating a shift mechanism with a standby spring. [Figure 6] FIG. 2 is a diagram showing a main part of a control configuration of a vehicle. [Figure 7] FIG. 4 is a diagram showing motor characteristics. [Figure 8] FIG. 4 is a diagram showing an example of a vehicle gear shift map. [Figure 9] FIG. 4 is a flowchart showing a first example of a first gear shift control. [Figure 10]5 is an explanatory diagram of an engagement force and a release force of a dog clutch. FIG. [Figure 11] FIG. 10 is a diagram showing an example of a timing chart corresponding to FIG. [Figure 12] FIG. 11 is a flowchart showing a second example of the first gear shift control. [Figure 13] FIG. 13 is a diagram showing an example of a timing chart corresponding to FIG. 12. [Figure 14] FIG. 4 is a flowchart showing a first example of a second gear shift control. [Figure 15] FIG. 15 is a diagram showing an example of a timing chart corresponding to FIG. 14. [Figure 16] FIG. 11 is a flowchart showing a second example of the second gear shift control. [Figure 17] FIG. 17 is a diagram showing an example of a timing chart corresponding to FIG. 16. [Figure 18] FIG. 11 is a flowchart showing a first example of a third gear shift control. [Figure 19] FIG. 19 is a diagram showing an example of a timing chart corresponding to FIG. 18. [Figure 20] FIG. 11 is a flowchart showing a second example of the third gear shift control. [Figure 21] FIG. 21 is a diagram showing an example of a timing chart corresponding to FIG. 20. [Figure 22] FIG. 4 is an explanatory diagram of the operating positions of the shift actuator in the case of a first gear shift control. [Diagram 23] FIG. 11 is an explanatory diagram of the operating positions of the shift actuator in the case of a second gear shift control. [Figure 24] FIG. 11 is an explanatory diagram of the operating positions of the shift actuator in the case of a third gear shift control. [Diagram 25] FIG. 11 is a flowchart showing a first example of a fourth gear shift control. [Figure 26] FIG. 23 is a diagram showing an example of a timing chart corresponding to FIG. 22. [Figure 27] FIG. 13 is a flowchart showing a second example of the fourth gear shift control. [Figure 28]FIG. 25 is a diagram showing an example of a timing chart corresponding to FIG. 24. [Figure 29] FIG. 1 is a diagram showing a first modified example of a vehicle. [Diagram 30] FIG. 13 is a diagram showing a second modified example of the vehicle. [Diagram 31] FIG. 13 is a diagram showing a third modified example of a vehicle. [Diagram 32] FIG. 13 is a diagram showing a fourth modified example of the vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] (First embodiment) FIG. 1 is a schematic diagram of a vehicle 100. The vehicle 100 includes a front-wheel drive system fds arranged in a relatively forward position (hereinafter referred to as the "front-wheel side") in the vehicle 100, and a rear-wheel drive system rds arranged in a relatively rearward position (hereinafter referred to as the "rear-wheel side"). In this embodiment, the rear-wheel drive system rds is configured similarly to the front-wheel drive system fds, with the arrangement of each component reversed in the vehicle front-rear direction compared to the front-wheel drive system fds. For this reason, the front-wheel drive system fds and the rear-wheel drive system rds will be described below mainly using the front-wheel drive system fds as an example. The components of the rear-wheel drive system rds are distinguished from the components of the front-wheel drive system fds by using the identification character "r" indicating rear instead of "f" indicating front. The names of the components of the rear-wheel drive system rds can also be distinguished by using the word "rear" instead of "front".

[0012] The front-wheel drive system fds includes a front motor 10f, front drive wheels 11f, a front inverter 14f, and a front transmission 16f. The front motor 10f is a drive motor and drives the front drive wheels 11f (left front drive wheel 11fL and right front drive wheel 11fR). Similarly, the rear motor 10r, which is a drive motor, drives the rear drive wheels 11r (left rear drive wheel 11rL and left rear drive wheel 11rR). Therefore, the vehicle 100 is configured as a four-wheel drive vehicle.

[0013] The front motor 10f is configured as a three-phase AC motor, and generates a front driving force DFf by receiving a supply of electric power from a battery 15 as a power source. The front driving force DFf generated by the front motor 10f is transmitted to the front driving wheels 11f via a front transmission 16f and a front drive shaft 21f. The front motor 10f further generates a negative front driving force DFf, i.e., a regenerative driving force, when it is rotated by the front driving wheels 11f while the vehicle 100 is running, and converts the generated regenerative driving force into AC power.

[0014] The front inverter 14f includes a switching circuit that performs switching to convert the power from the battery 15 into three-phase AC. The front inverter 14f also converts AC power obtained based on the regenerative driving force of the front motor 10f into DC power by switching, and supplies the DC power to the battery 15.

[0015] The front transmission 16f is provided in a power transmission path connecting the front motor 10f and the front drive wheels 11f, and transmits power between the front motor 10f and the front drive wheels 11f. The front transmission 16f has two front gears Shf, a high gear with a relatively low gear ratio and a low gear with a relatively high gear ratio. The front transmission 16f includes a low gear train 22f, a high gear train 24f, a dog clutch 26f, and a final gear 30f that distributes the power of the output shaft 32f to the left front drive wheel 11fL and the right front drive wheel 11fR.

[0016] The low gear train 22f includes a drive gear 40f and a driven gear 41f that mesh with each other. The drive gear 40f is rotatably provided on the input shaft 20f of the front motor 10f without being fixed thereto. The driven gear 41f is fixed to the output shaft 32f of the front motor 10f. In the low gear train 22f, the number of teeth of the driven gear 41f is larger than the number of teeth of the drive gear 40f. Therefore, the gear ratio of the front transmission 16f becomes larger than 1 when the front driving force DFf is transmitted from the input shaft 20f to the output shaft 32f via the low gear train 22f, and at this time, the front gear stage Shf becomes low.

[0017] The high gear train 24f includes a drive gear 42f and a driven gear 43f that mesh with each other. The drive gear 42f is rotatably provided on the input shaft 20f without being fixed thereto. The driven gear 43f is fixed to the output shaft 32f. In the high gear train 24f, the number of teeth of the driven gear 43f is configured to be approximately equal to or smaller than the number of teeth of the drive gear 42f. Therefore, the gear ratio of the front transmission 16f becomes approximately 1 or greater than 1 when the front driving force DFf is transmitted from the input shaft 20f to the output shaft 32f via the high gear train 24f, and at this time the front gear shift stage Shf becomes high.

[0018] The dog clutch 26f is a variable speed clutch, and is configured as a mesh clutch including a sleeve 44f, a first dog tooth 401f, and a second dog tooth 421f. The sleeve 44f is provided on a hub 47f fixed to the input shaft 20f so as to be slidable in the axial direction, and is adjacent to the drive gear 40f and the drive gear 42f in the axial direction. The sleeve 44f has an outer circumferential groove 441f, and a shift fork 54 (shift fork 54f) described later engages with the outer circumferential groove 441f.

[0019] The first dog teeth 401f are provided on a drive gear 40f of the low gear train 22f, and the second dog teeth 421f are provided on a drive gear 42f of the high gear train 24f. The sleeve 44f has dog teeth 442f consisting of internal teeth, and selectively meshes with the first dog teeth 401f and the second dog teeth 421f consisting of external teeth by moving in the axial direction.

[0020] When the sleeve 44f moves to the low position, which is the engagement position with the first dog tooth 401f, the hub 47f and the drive gear 40f are connected by the sleeve 44f. As a result, the dog clutch 26f is in a state where it transmits power between the input shaft 20f and the output shaft 32f via the low gear train 22f, and the front gear Shf becomes low.

[0021] When the sleeve 44f moves to the high position where it engages with the second dog teeth 421f, the hub 47f and the drive gear 42f are connected by the sleeve 44f. As a result, the dog clutch 26f transmits power between the input shaft 20f and the output shaft 32f via the high gear train 24f, and the front gear Shf becomes high.

[0022] When the sleeve 44f moves to the neutral position where it does not mesh with either the first dog tooth 401f or the second dog tooth 421f, the dog clutch 26f is in a state where it cuts off the power transmission between the input shaft 20f and the output shaft 32f, that is, in a neutral state. Therefore, in the neutral position, the power transmission between the front motor 10f and the front driving wheels 11f is cut off.

[0023] Next, the front wheel drive system fds and the rear wheel drive system rds will be further explained. In the following, matters common to the front wheel drive system fds and the rear wheel drive system rds will be explained comprehensively, omitting the identification letters "f" and "r" as appropriate. For example, when explaining the front transmission 16f and the rear transmission 16r comprehensively, they will be referred to as the transmission 16. The transmission 16 further includes a shift mechanism 50.

[0024] FIG. 2 is an external view of the shift mechanism 50. FIG. 3 is a front view of the periphery of the cam plate 53. FIG. 4 is a schematic diagram of the shift mechanism 50. FIGS. 2 to 4 show a case where the shift mechanism 50 is a shift mechanism without a standby spring, which transmits a clutch actuating force from the ACTR 51 to the dog clutch 26 without a spring. The shift mechanism 50 is a mechanism for engaging and releasing the dog clutch 26, and transmits a clutch actuating force from the shift actuator 51 to the dog clutch 26. The shift mechanism 50 (shift mechanism 50f, shift mechanism 50r) has a rotating rod 52, a cam plate 53, a shift fork 54, a fork rod 55, and a check mechanism 56 in addition to the shift actuator 51. Hereinafter, the shift actuator 51 will be simply referred to as the ACTR 51.

[0025] The ACTR 51 is constituted by a motor, and rotates the cam plate 53 fixed to the rotating rod 52. The cam plate 53 has a cam groove 531. The cam groove 531 extends in an arc shape around the rotation center of the cam plate 53. A pin 541 of a shift fork 54 engages with the cam groove 531. The cam groove 531 guides the pin 541 in response to the rotation of the cam plate 53, thereby moving the shift fork 54 via the pin 541. The shift fork 54 engages with an outer peripheral groove 441 of the sleeve 44. The outer peripheral groove 441 engages with the shift fork 54 so as to be slidable in the rotational direction. A fork rod 55 passes through the shift fork 54, and the shift fork 54 is provided so as to be slidable in the axial direction on the fork rod 55. The shift fork 54 slides in the axial direction of the fork rod 55 by a clutch operating force transmitted from the ACTR 51 via the rotating rod 52 and the cam plate 53. The sleeve 44 moves in the axial direction of the fork rod 55 due to the clutch operating force transmitted from the shift fork 54, and thereby moves to the low side and high side, i.e., the low gear train 22 side and the high gear train 24 side.

[0026] The check mechanism 56 is provided in the housing of the transmission 16. The check mechanism 56 is configured such that a check sleeve 561 and a check spring 562 are inserted into a hole provided in the housing, and the hole is sealed with a check plug 563. The check mechanism 56 urges the check sleeve 561 toward the engagement portion 542 of the shift fork 54 by the check spring 562. The check sleeve 561 engages with a V-shaped check groove of the engagement portion 542 when the sleeve 44 is located in the neutral position. The check sleeve 561 engages with one of the engagement slopes on both sides of the check groove of the engagement portion 542 when the sleeve 44 is located in the engagement position of the dog clutch 26, that is, the low position or the high position. This brings the check mechanism 56 into an engaged state, and the operating position of the shift fork 54 is maintained. The engagement of the check mechanism 56 is released when the clutch operating force transmitted to the shift fork 54 moves the check sleeve 561 backward against the spring force of the check spring 562.

[0027] The shift mechanism 50 may be a shift mechanism with a standby spring, which will be described next.

[0028] FIG. 5 is a schematic diagram of a shift mechanism 50 with a standby spring. In this case, the shift fork 54 is divided into a shaft portion 543 provided on the fork rod 55 and a main body portion 544 that engages with the sleeve 44. The pin 541 is provided on the shaft portion 543, and the engagement portion 542 is provided on the main body portion 544. A cylindrical housing portion 547 is provided on the main body portion 544. On both axial sides of the housing portion 547, openings having a smaller diameter than the housing portion 547 are provided. Cylindrical engagement members 545 and 546 and a spring 57 are provided in the housing portion 547. The spring 57 is a standby spring for putting the sleeve 44 into standby for the operation of the ACTR 51, and is provided between the engagement members 545 and 546. The shaft portion 543 penetrates the engaging members 545, 546, and spring 57, and the engaging members 545 and 546 are provided slidably relative to the shaft portion 543. The engaging members 545 and 546 each have an enlarged diameter portion and a reduced diameter portion, and the reduced diameter portion is disposed facing the axially outward side of the accommodation portion 547. The engaging members 545 and 546 are provided between two flanges provided on the shaft portion 543. In each of the engaging members 545 and 546, the reduced diameter portion forms an abutment portion that abuts against the flange of the shaft portion 543, and the enlarged diameter portion forms an abutment portion that abuts against the opening of the main body portion 544. The shaft portion 543 and the main body portion 544 may be formed of a plurality of members.

[0029] In the shift mechanism 50 configured as described above, a clutch actuating force is transmitted from the ACTR 51 to the dog clutch 26 via the spring 57 as described below. For example, when the dog clutch 26 engaged on the high side is to be released, when the ACTR 51 generates a clutch actuating force toward the low side, the shaft 543 moves to the low side and pushes the engaging member 546 to the low side. As a result, the engaging member 545, the engaging member 546, and the spring 57 move to the low side, and the engaging member 545 abuts against the opening of the main body 544. When the engaging member 545 further pushes the main body 544 to the low side from this state, the movement of the main body 544 is prevented while the check mechanism 56 is engaged. Therefore, when the shaft 543 moves to the low side, the spring 57 is compressed via the engaging member 546. Then, when the engagement of the check mechanism 56 is released by the spring force of the spring 57, the main body 544 moves to the low side and abuts against the sleeve 44.

[0030] In the engaged state, the dog clutch 26 generates a fastening force Fcl according to the torque TQm of the motor 10, as described later. The fastening force Fcl functions as a resistance force against the release of the dog clutch 26. Therefore, while the fastening force Fcl prevents the dog clutch 26 from being released, the movement of the sleeve 44 to the low side is prevented, and the main body portion 544 cannot move to the low side either. As a result, the shaft portion 543 moves to the low side, and the spring 57 is further compressed. Then, the clutch operating force stored in the spring 57 is transmitted to the dog clutch 26, and the clutch operating force is transmitted from the ACTR 51 to the dog clutch 26 via the spring 57. When the movement of the sleeve 44 to the low side is no longer prevented by the fastening force Fcl, the spring 57 moves the sleeve 44 to the low side.

[0031] FIG. 6 is a diagram showing the main parts of the control configuration of the vehicle 100. The vehicle 100 further includes a controller 1. The controller 1 is a gear shift control device for the vehicle 100, and includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). Various signals are input to the controller 1 from sensors and switches 2. The sensors and switches 2 include, for example, an accelerator opening sensor for detecting an accelerator opening APO that indicates the amount of depression of the accelerator pedal, a vehicle speed sensor for detecting a vehicle speed VSP, a position sensor for detecting an operating position of the ACTR 51, a position sensor for detecting an operating position of the sleeve 44, and a rotation speed sensor for detecting a rotation speed Nm of the motor 10. The controller 1 is programmed to control the inverter 14 and the ACTR 51 based on the input signals and the like. The controller 1 controls the inverter 14 to thereby control the motor 10.

[0032] FIG. 7 is a diagram showing the characteristics of the motor 10. In FIG. 7, the solid line indicates the torque TQm of the motor 10, and the dashed line indicates the output Pm of the motor 10. As shown in FIG. 7, the motor 10 has a constant torque region R1 and a constant output region R2. The constant torque region R1 is a region in which the torque TQm is constant according to the rotation speed Nm of the motor 10, and the rotation speed Nm is a region in which the rotation speed Nm is lower than the rotation speed Nm1. The constant output region R2 is a region in which the output Pm is constant according to the rotation speed Nm of the motor 10, and the rotation speed Nm is a region in which the rotation speed Nm is higher than the rotation speed Nm1 and lower than the rotation speed Nm2. Within the constant torque region R1, the torque Qm is constant at the maximum torque regardless of the rotation speed Nm, and the output Pm can be increased by increasing the rotation speed Nm. Therefore, within the constant torque region R1, an increase in the driving force DF can be expected by running at a low gear Sh, and acceleration can be achieved without upshifting. Within the constant power output region R2, the output Pm is constant at the maximum output, so the rotation speed Nm and the torque Tm are inversely proportional to each other, and increasing the rotation speed Nm reduces the torque TQm. Therefore, within the constant power output region R2, even if the vehicle is driven at a low gear Sh, no increase in the driving force DF can be expected. In this embodiment, the same motor is used for the front motor 10f and the rear motor 10r.

[0033] In the vehicle 100, power is transmitted from the motor 10 to the drive wheels 11 via the transmission 16. Therefore, the maximum driving force and maximum rotation speed of the motor 10 can be improved by shifting gears, and this makes it possible to suppress an increase in the size of the motor 10. However, since the transmission 16 shifts gears via the neutral position, the power transmission is temporarily cut off during the gear shift. Therefore, even though the drive source is the motor 10 that can generate power continuously over the entire driving range, there is a concern that the power transmission is temporarily cut off during the gear shift, which may cause inconveniences such as a feeling of discomfort to the driver or a decrease in driving stability.

[0034] In relation to the above, in this embodiment, the vehicle 100 is a four-wheel drive vehicle in which the front motor 10f drives the front drive wheels 11f and the rear motor 10r drives the rear drive wheels 11r. Therefore, when the front transmission 16f is shifted, the rear motor 10r can compensate for the drive force DF, and when the rear transmission 16r is shifted, the front motor 10f can compensate for the drive force DF. In other words, since the drive force DF can be compensated for during shifting, it is possible to suppress the occurrence of an uncomfortable feeling.

[0035] However, even in this case, depending on the driving state of the vehicle 100, the requested driving force DF_REQ may become larger in absolute value than the maximum driving force of the motor 10, and the driving force DF that can be compensated for by the motor 10 may be insufficient for the requested driving force DF_REQ. Alternatively, the vehicle 100 may temporarily switch from a four-wheel drive state to a two-wheel drive state, which may result in a decrease in the driving stability of the vehicle 100.

[0036] 8 is a diagram showing an example of a gear shift map of the vehicle 100. In the gear shift map, the front gear Shf of the front transmission 16f and the rear gear Shr of the rear transmission 16r are set according to the vehicle speed VSP and the required driving force DF_REQ. The region R_LL indicates a region where the front gear Shf and the rear gear Shr are both set to low. The region R_HL indicates a region where the front gear Shf is set to high and the rear gear Shr is set to low. The region R_HH indicates a region where the front gear Shf and the rear gear Shr are both set to high. The region R_LL is also set outside the illustrated range where the required driving force DF_REQ and the vehicle speed VSP are negative.

[0037] The limit driving force DF_LMT1 indicates the sum of the driving forces DF that can be generated by the front motor 10f and the rear motor 10r when the front gear Shf and the rear gear Shr are both in low. The limit driving force DF_LMT2 indicates the driving force DF that can be generated by a single motor 10, i.e., the front motor 10f or the rear motor 10r, when the gear Sh is in low. The maximum driving force that can be generated is the maximum driving force when it is positive, and the minimum driving force, i.e., the maximum regenerative driving force, when it is negative.

[0038] Therefore, in the region R_OVER where the required driving force DF_REQ is greater than the positive limit driving force DF_LMT2, the required driving force DF_REQ cannot be satisfied by the front motor 10f or the rear motor 10r alone. In other words, a situation occurs in which the driving force DF that can be compensated for by the motor 10 is insufficient for the required driving force DF_REQ.

[0039] For example, when a kickdown shift is performed from the region R_HL to the region R_LL indicated by the arrow GS_KD, the requested driving force DF_REQ exceeds the positive limit driving force DF_LMT2. As a result, when the front derailleur 16f undergoing the kickdown shift is in neutral, the requested driving force DF_REQ cannot be satisfied by the rear motor 10r alone. In other words, the rear motor 10r cannot fully compensate for the driving force DF.

[0040] When an auto upshift is performed from the region R_LL to the region R_HL indicated by the arrow GS_UP1, the front derailleur 16f is upshifted in a state in which the requested driving force DF_REQ is greater than the positive limit driving force DF_LMT2. As a result, when in neutral at this time, the requested driving force DF_REQ cannot be satisfied by the rear motor 10r alone. Also, when an auto upshift is performed from the region R_HL to the region R_HH indicated by the arrow GS_UP2, the front motor 10f alone cannot satisfy the requested driving force DF_REQ when the rear derailleur 16r that is upshifted is in neutral.

[0041] The arrow GS_DOWN indicates a case where a regenerative deceleration downshift is performed from the region R_HH to the region R_HL. In this example, the rear transmission 16r is downshifted when the requested driving force DF_REQ is smaller in absolute value than the negative limit driving force DF_LMT2. Therefore, in this case, the requested driving force DF_REQ can be satisfied by the front motor 10f alone. However, in this case, the vehicle 100 is in two-wheel drive state when the rear transmission 16r that is downshifted is in neutral, which may result in a decrease in driving stability.

[0042] In view of the above circumstances, in this embodiment, the controller 1 is programmed to perform the gear shift control described below. The controller 1 is configured to have a control unit by being programmed to perform the gear shift control described below.

[0043] (First gear shift control) FIG. 9 is a flowchart showing a first example of the first gear shift control performed by the controller 1. The first gear shift control is kick-down gear shift control, and the first example shows the case where the shift mechanism 50 does not have the standby spring described above with reference to FIG. 4. FIG. 9 shows the case where the front transmission 16f is downshifted by the kick-down gear shift indicated by the arrow GS_KD described in FIG. 8. The first gear shift control can be performed when the motor 10 on the side of the transmission 16 to be downshifted, that is, the front motor 10f in this case, is operating in the constant torque region R1. The first gear shift control can also be applied to the rear transmission 16r. The controller 1 can repeatedly execute the process shown in this flowchart.

[0044] In step S1, the controller 1 judges whether the accelerator opening APO is equal to or greater than a predetermined opening APO1. The predetermined opening APO1 is an opening lower than the kickdown shift execution opening APO_KD of the front transmission 16f and is set in advance. The predetermined opening APO1 can be set based on the time required for the operating position of the front ACTR 51f to change from the high position to the neutral position. The predetermined opening APO1 can be set smaller as the degree of increase in the accelerator opening APO increases. If the judgment in step S1 is negative, the process is temporarily terminated. If the judgment in step S1 is positive, the process proceeds to step S2. In this case, the controller 1 judges whether the fastening force Fclf of the dog clutch 26f is greater than the release force Factrf of the dog clutch 26f by the front ACTR 51f.

[0045] FIG. 10 is an explanatory diagram of the fastening force Fcl and the release force Factr of the dog clutch 26. FIG. 10 is an enlarged schematic view of the meshing portion of the dog clutch 26 as viewed in the axial direction. When the dog clutch 26 is released while the torque TQm of the motor 10 is being transmitted from the sleeve 44 to the drive gear 40, the back taper of the first dog tooth 401 provided on the drive gear 40 comes into contact with the back taper of the dog tooth 442 of the sleeve 44. Therefore, when the sleeve 44 is moved in the release direction, a vertical force acts on the back taper of the dog tooth 442. The vertical force is resolved into a tangential force corresponding to the torque TQm and an axial force. As a result, the axial force becomes the fastening force Fcl and prevents the dog clutch 26 from being released. Therefore, when the fastening force Fcl is greater than the release force Factr, the dog clutch 26 is not released even if the sleeve 44 is moved in the release direction by the ACTR 51. The fastening force Fcl can be calculated based on the back taper angle of the dog teeth 442 and the torque TQm, and the releasing force Factr can be calculated based on the torque of the ACTR51.

[0046] Returning to FIG. 9, if the determination in step S2 is negative, the process is temporarily terminated, and if the determination in step S2 is positive, the process proceeds to step S3A. In this case, the controller 1 operates the front ACTR 51f to the waiting position. The waiting position is an operating position of the ACTR 51 that causes the dog clutch 26 to wait for release, and is set to a position toward the neutral position side from the fastening position by an operating distance according to the backlash of the components of the power transmission path connecting the ACTR 51 and the dog clutch 26. The backlash includes, for example, an axial gap between the outer circumferential groove 441 of the sleeve 44 and the fork portion of the shift fork 54. In step S3A, the front ACTR 51f is operated toward the neutral position side by the operation to the waiting position. In step S3A, since the fastening force Fcl is greater than the release force Factr, even if the front ACTR 51f is operated before a gear shift command, the dog clutch 26 is not released against the intention of operating to the waiting position.

[0047] In step S4, the controller 1 judges whether the accelerator opening APO is equal to or greater than a preset kick-down shift execution opening APO_KD. When the accelerator opening APO is equal to or greater than the kick-down shift execution opening APO_KD, it is judged that the conditions for executing the kick-down shift are satisfied, and a shift instruction for the kick-down shift is issued. The shift instruction includes an instruction to shift to the neutral position and an instruction to shift to the engagement position, i.e., the low position in this case, which is executed thereafter, and when the conditions for executing the kick-down shift are satisfied, a shift instruction to the neutral position is issued. If the judgment in step S4 is affirmative, the process proceeds to step S5, and the controller 1 executes the shift. In step S5, a kick-down shift is executed to change the front gear Shf from high to low. In the kick-down shift, as described later, the torque TQmf is reduced in absolute value, the dog clutch 26f is released on the high side, the dog clutch 26f is rotated in synchronization with the dog clutch 26f, the dog clutch 26f is engaged on the low side, and the torque TQmf is increased in absolute value. After step S5, the process ends.

[0048] If the determination in step S4 is negative, the process proceeds to step S6, where the controller 1 determines whether or not the elapsed time since the front ACTR 51f was operated is equal to or greater than a predetermined time. The predetermined time is a timeout time for the shift control that is assumed to be executed due to the positive determination in step S1, that is, kick-down shifting in this case, and is set in advance. The predetermined time may be set to a different value or the same value depending on the shift control that is assumed to be executed. If the determination in step S6 is negative, the process returns to step S4. As a result, it is determined whether or not the accelerator opening APO is equal to or greater than the kick-down shift execution opening APO_KD until the predetermined time has elapsed.

[0049] If the determination in step S6 is affirmative, the process proceeds to step S7, where the controller 1 operates the front ACTR 51f to return the front gear Shf to high. In other words, in this case, the execution condition for the kickdown shift is not satisfied within the predetermined time, resulting in a timeout, so the front ACTR 51f is returned to its original position before it was operated toward the neutral position. After step S7, the process ends for the time being.

[0050] Fig. 11 is a diagram showing an example of a timing chart corresponding to the flowchart shown in Fig. 9. At timing T1, the accelerator pedal is depressed, and the accelerator opening APO and torque TQmf start to increase. At timing T1, the dog clutch 26 is engaged on the high side, so the rotation speed Nmf of the front motor 10f is the same as the rotation speed Nhf of the high side drive gear 42f. Both the rotation speed Nhf of the high side drive gear 42f and the rotation speed Nlf of the low side drive gear 40f are rotation speeds corresponding to the vehicle speed VSP.

[0051] The accelerator opening APO reaches a predetermined opening APO1 at timing T2. At timing T2, the torque TQmf is greater than zero, and the fastening force Fclf based on the torque TQmf is greater than the release force Factrf by the front ACTR 51f. Therefore, at timing T2, the front ACTR 51f starts to move to the waiting position, and the operating position starts to change from the high position (H) toward the neutral position (N). The operating position of the front ACTR 51f then gradually changes to the waiting position, thereby eliminating any backlash in the power transmission path between the front ACTR 51f and the sleeve 44f. The operating position of the front ACTR 51f reaches the waiting position before timing T3 when a shift command is issued.

[0052] At timing T3, the accelerator opening APO reaches the kick-down shift execution opening APO_KD. As a result, a shift command to the neutral position is issued, and in response to this, a kick-down shift is started. In the kick-down shift, first, the torque TQmf is reduced in absolute value in order to release the dog clutch 26f that is engaged on the high side. At this time, in the vehicle 100, the torque TQmr is increased in absolute value to compensate for the driving force DF. However, as described above, the driving force DF cannot be compensated for by the rear motor 10r alone. The torque TQmf becomes zero at timing T4, and at this time, the release force Factrf of the dog clutch 26f is larger than the engagement force Fclf. For this reason, in the first example in which the shift mechanism 50 does not have a standby spring, when the torque TQmf becomes zero at timing T4, the release of the dog clutch 26f on the high side is started, and this starts the operation of the front ACTR 51f to the neutral position. At timing T4, the backlash has already been eliminated. Therefore, the actuation position of the sleeve 44f starts to change toward the neutral position at the timing T4 when the actuation of the front ACTR 51f toward the neutral position starts.

[0053] The operating positions of the front ACTR 51f and the sleeve 44f reach the neutral position at timing T5. When the operating position of the sleeve 44f reaches the neutral position, the release of the dog clutch 26f is completed, and rotation synchronization for engaging the dog clutch 26f on the low side is started. As a result, the torque TQmf starts to increase, and the rotation speed Nmf starts to rise higher than the rotation speed Nhf of the high side drive gear 42f. In the rotation synchronization, the rotation speed of the sleeve 44f indicated by the rotation speed Nmf of the front motor 10f is matched to the rotation speed Nlf of the low side drive gear 40f. In the rotation synchronization, the torque TQmf is controlled according to a predetermined profile, and becomes zero at timing T6.

[0054] At timing T6, the rotation speed Nmf of the front motor 10f reaches the rotation speed Nlf of the drive gear 40f on the low side, and rotation synchronization is completed. As a result, a shift command to the low position (L) is issued, and engagement of the dog clutch 26f on the low side is started. As a result, the operating position of the front ACTR 51f starts to change to the low position side. At this time, the operating position of the sleeve 44f starts to change to the low position side with a delay according to the backlash. At timing T7, the operating positions of the front ACTR 51f and the sleeve 44f become the low position, and engagement of the dog clutch 26 on the low side is completed. As a result, the torque TQmf starts to increase in absolute value accordingly, and when the torque TQmf reaches a magnitude according to the accelerator opening APO at timing T8, the kickdown shift is completed.

[0055] In the comparative example shown by the broken line, the front ACTR 51f is not actuated toward the neutral position at timing T2, and begins to actuate toward the neutral position at timing T4 when the torque TQmf becomes zero. As a result, in the present embodiment, the actuation of the front ACTR 51f is advanced from timing T4 to timing T2, and backlash is eliminated before a shift command is issued at timing T3, compared to the comparative example. Also, in the comparative example, the actuation position of the sleeve 44f begins to change toward the neutral position from timing T5 with a delay corresponding to the backlash relative to the actuation position of the front ACTR 51f. As a result, a delay is also generated in the subsequent shift operation, and the timing at which the kickdown shift is completed is timing T9, which is later than timing T8. Therefore, in the present embodiment, the shift time is shortened by the amount that the shift completion timing is advanced, compared to the comparative example. Therefore, even if the rear driving force DFr that can be compensated for by the rear motor 10r is insufficient for the required driving force DF_REQ during the kickdown shift of the front transmission 16f, the driver is prevented from feeling uncomfortable.

[0056] Next, a second example of the first gear shift control performed by the controller 1 will be described with reference to FIG. 12. The second example shows a case where the shift mechanism 50 has the standby spring as described above with reference to FIG. 5. The flowchart shown in FIG. 12 is the same as the flowchart shown in FIG. 9, except that step S3B is provided instead of step S3A. Therefore, to explain step S3B, in step S3B, the controller 1 operates the front ACTR 51f to the neutral position. That is, in the second example, when operating the front ACTR 51f toward the neutral position, the front ACTR 51f is operated to the neutral position to eliminate backlash.

[0057] FIG. 13 is a diagram showing an example of a timing chart corresponding to FIG. 12. The following mainly describes the differences from the first example shown in FIG. 11. In the second example, when the accelerator opening APO reaches a predetermined opening APO1 at timing T11, the operation of the front ACTR 51f to the neutral position is started. Also, before a gear shift command is issued at timing T12, backlash is eliminated. Then, when the release force Factrf exceeds the sum of the fastening force Fcl and the engaging force of the check mechanism 56f due to an increase in the spring force of the spring 57f and a decrease in the torque TQmf in absolute value, the engagement of the check mechanism 56f is released, and the operating position of the sleeve 44f starts to change to the neutral position side. The operating position of the sleeve 44f becomes the neutral position at timing T15, delayed from the front ACTR 51f. Thereafter, rotation synchronization is performed between timing T15 and timing T16, the dog clutch 26f is engaged on the low side between timing T16 and timing T17, the torque TQmf increases in absolute value, and the kickdown shift is completed at timing T18.

[0058] In the case of the comparative example shown by the broken line, the front ACTR 51f starts to operate in the following manner in response to a gear shift command. That is, since the shift mechanism 50 in the second example has a waiting spring, the front ACTR 51f starts to operate to the neutral position at timing T13 before timing T14 in response to a gear shift command without waiting for timing T14 when the torque TQmf becomes zero. However, the front ACTR 51f only starts to operate in response to a gear shift command. Therefore, in the case of this embodiment, the operation of the front ACTR 51f is advanced from timing T13 to timing T11 compared to the comparative example, and thus backlash is eliminated before the gear shift command is issued at timing T12. In addition, in the comparative example, the operation of the sleeve 44 is delayed, so that the subsequent gear shift operation is also delayed, and the kickdown gear shift is completed at timing T19 after timing T18. Therefore, in the case of this embodiment, the gear shift completion timing is advanced, and the gear shift time is shortened, compared to the comparative example. As a result, the driver is prevented from feeling uncomfortable, as in the first example.

[0059] (Second gear shift control) Fig. 14 is a flowchart showing a first example of the second gear shift control performed by the controller 1. The second gear shift control is auto upshift control, and Fig. 14 shows a case where the front transmission 16f is upshifted by the auto upshift indicated by the arrow GS_UP1 described in Fig. 8. The second gear shift control can be performed when the motor 10 on the transmission 16 side that is auto upshifted, that is, the front motor 10f in this case, is operating in the constant output region R2. The second gear shift control can also be applied to the rear transmission 16r.

[0060] In step S11, the controller 1 judges whether the vehicle speed VSP is equal to or higher than a first predetermined vehicle speed VSP1. The first predetermined vehicle speed VSP1 is a vehicle speed VSP lower than the auto-upshift execution vehicle speed VSP_UP and is set in advance. The first predetermined vehicle speed VSP1 can be set based on the time required for the operating position of the front ACTR 51f to change from the low position to the neutral position. The first predetermined vehicle speed VSP1 can be set smaller as the acceleration increases. If the judgment in step S11 is negative, the process is temporarily terminated. If the judgment in step S11 is positive, the process proceeds to step S12, where it is judged whether the fastening force Fclf is greater than the releasing force Factrf, as in the first shift control. If the judgment in step S12 is positive, the front ACTR 51f is operated to the waiting position in step S13A, as in the first example described above.

[0061] In step S14, the controller 1 judges whether the vehicle speed VSP has become equal to or higher than the auto-upshift execution vehicle speed VSP_UP. The auto-upshift execution vehicle speed VSP_UP is set in advance by the map data shown in FIG. 8. When the vehicle speed VSP has become equal to or higher than the auto-upshift execution vehicle speed VSP_UP, it is judged that the execution condition for the auto-upshift is satisfied, and an instruction for shifting the auto-upshift is issued. When the judgment in step S14 is affirmative, an instruction for shifting to the neutral position is issued, as in the first shift control. When the judgment in step S14 is affirmative, the process proceeds to step S15, and the controller 1 executes the shift. In step S15, an auto-upshift is performed to change the front gear Shf from low to high. In the auto-upshift, as described later, the torque TQmf is reduced in absolute value, the dog clutch 26f is released on the low side, the dog clutch 26f is synchronized with the rotation of the dog clutch 26f, the dog clutch 26f is engaged on the high side, and the torque TQmf is increased in absolute value. After step S15, the process is temporarily terminated.

[0062] If the determination in step S14 is negative, the process proceeds to step S16, where it is determined whether or not the elapsed time is equal to or longer than a predetermined time, as in the first shift control. If the determination in step S16 is negative, the process returns to step S14. If the determination in step S16 is positive, the process proceeds to step S17, where the controller 1 operates the front ACTR 51f to return the front gear Shf to low. After step S17, the process ends for the time being.

[0063] Fig. 15 is a diagram showing an example of a timing chart corresponding to Fig. 14. At timing T21, the vehicle speed VSP becomes equal to or greater than the first predetermined vehicle speed VSP1, and the operation of the front ACTR 51f to the waiting position is started. As a result, the operating position of the front ACTR 51f starts to change toward the neutral position. The operating position of the front ACTR 51f then gradually changes and becomes the waiting position before timing T22 when a shift command is issued, thereby eliminating backlash.

[0064] At timing T22, the vehicle speed VSP becomes equal to or higher than the auto-upshift execution vehicle speed VSP_UP. As a result, a shift command to the neutral position is issued, and in response to this, the auto-upshift is started. In the auto-upshift, the torque TQmf starts to decrease in absolute value in order to release the dog clutch 26f engaged on the low side. At this time, the torque TQmr in the vehicle 100 is increased in absolute value to compensate for the driving force DF. However, as described above, the rear motor 10r alone cannot compensate for the driving force DF. The release of the dog clutch 26f on the low side starts at timing T23 when the torque TQmf becomes zero, and this starts the operation of the front ACTR 51f to the neutral position. Since the backlash has already been eliminated at timing T23, the operating position of the sleeve 44f also starts to change toward the neutral position. At timing T24, the release of the dog clutch 26f on the low side is completed, and rotation synchronization starts. The torque TQmf is controlled on the negative side according to the profile at the time of rotation synchronization. Therefore, the rotation speed Nmf starts to decrease from timing T24, and the rotation speed of the sleeve 44f approaches the rotation speed Nhf of the high-side drive gear 42f. The torque TQmf becomes zero at timing T25.

[0065] At timing T25, rotation synchronization is completed. As a result, a shift command to the high position is issued, and engagement of the dog clutch 26f on the high side begins. As a result, the operating position of the front ACTR 51f begins to change toward the high position. At this time, the operating position of the sleeve 44f begins to change toward the high position with a delay corresponding to the backlash. At timing T26, the operating positions of the front ACTR 51f and the sleeve 44f become the high position, and engagement of the dog clutch 26 on the high side is completed. As a result, the torque TQmf begins to increase in absolute value accordingly. At timing T27, the torque TQmf returns to the original torque TQmf, that is, the torque TQm immediately before the shift, thereby completing the auto upshift.

[0066] In the comparative example shown by the broken line, the front ACTR 51f is not actuated toward the neutral position at timing T21, and starts to be actuated to the neutral position at timing T23 when the torque TQmf becomes zero. Therefore, the actuation position of the front ACTR 51f starts to change to the neutral position at timing T23, and the actuation position of the sleeve 44f starts to change to the neutral position from timing T23 with a delay according to the backlash. Therefore, in the present embodiment, the actuation of the front ACTR 51f is advanced from timing T23 to timing T21 compared to the comparative example, and backlash is eliminated before the shift command is issued at timing T23. Also, in the comparative example, the actuation of the sleeve 44f is delayed, so that the subsequent shift operation is also delayed, and the auto upshift is completed at timing T28 after timing T27. Therefore, in the present embodiment, the shift completion timing is advanced, and the shift time is shortened, compared to the comparative example. As a result, the driver is prevented from feeling uncomfortable.

[0067] Next, a second example of the second gear shift control performed by the controller 1 will be described with reference to Fig. 16. The flowchart shown in Fig. 16 is the same as the flowchart shown in Fig. 14, except that step S13B is provided instead of step S13A. Also, in step S13B, the front ACTR 51f is actuated to the neutral position, as in the second example described above, thereby eliminating backlash.

[0068] FIG. 17 is a diagram showing an example of a timing chart corresponding to FIG. 16. The following mainly describes the differences from the first example shown in FIG. 15. In the second example, when the vehicle speed VSP reaches the first predetermined vehicle speed VSP1 at timing T31, the operation of the front ACTR 51f to the neutral position is started. Also, before a shift command is issued at timing T32, the backlash is eliminated by the spring force of the spring 57f, and then when the release force Factrf exceeds the fastening force Fclf, the operating position of the sleeve 44f starts to change to the neutral position side. The operating position of the sleeve 44f becomes the neutral position at timing T34, delayed from the front ACTR 51f. After that, rotation synchronization is performed between timing T34 and timing T35, and the dog clutch 26f is fastened on the high side between timing T35 and timing T36, and the torque TQmf increases in absolute value, and the auto upshift is completed at timing T37.

[0069] In the comparative example shown by the broken line, the front ACTR 51f starts to operate to the neutral position in response to a shift command at timing T32, which is before timing T33 when the torque TQmf becomes zero. Therefore, in the present embodiment, the operation of the front ACTR 51f is advanced from timing T32 to timing T31, compared to the comparative example, so that backlash is eliminated before the shift command is issued at timing T32. In the comparative example, the operation of the sleeve 44f is delayed, so that the subsequent shift operation is also delayed, and the auto upshift is completed at timing T38, which is after timing T37. Therefore, in the present embodiment, the shift completion timing is advanced, and the shift time is shortened, compared to the comparative example. As a result, the driver is prevented from feeling uncomfortable, as in the first example.

[0070] (Third shift control) Fig. 18 is a flowchart showing a first example of the third gear shift control performed by the controller 1. The third gear shift control is a regenerative deceleration downshift control, and Fig. 18 shows a case where the rear transmission 16r is downshifted by the regenerative deceleration downshift indicated by the arrow GS_DOWN described in Fig. 8. The third gear shift control may also be applied to the front transmission 16f.

[0071] In step S21, the controller 1 judges whether the vehicle speed VSP has become equal to or lower than a second predetermined vehicle speed VSP2. The second predetermined vehicle speed VSP2 is a vehicle speed VSP higher than the regenerative deceleration downshift execution vehicle speed VSP_DOWN, and is set in advance. The second predetermined vehicle speed VSP2 can be set based on the time required for the rear ACTR 51r to move from the high position to the neutral position. The second predetermined vehicle speed VSP2 can be set higher as the deceleration increases. If the judgment in step S21 is negative, the process ends once. If the judgment in step S21 is positive, the process proceeds to step S22, where it is judged whether the fastening force Fclr is greater than the release force Factrr, as in the above-mentioned shift control. If the judgment in step S22 is positive, the rear ACTR 51r is operated to the waiting position in step S23A, as in the first example described above.

[0072] In step S24, the controller 1 judges whether the vehicle speed VSP has become equal to or lower than the regenerative deceleration downshift execution vehicle speed VSP_DOWN. The regenerative deceleration downshift execution vehicle speed VSP_DOWN is set in advance by the map data shown in FIG. 8. When the vehicle speed VSP has become equal to or lower than the regenerative deceleration downshift execution vehicle speed VSP_DOWN, it is judged that the execution condition for the regenerative deceleration downshift is satisfied, and a shift command for the regenerative deceleration downshift is issued. When the judgment in step S24 is affirmative, a shift command to the neutral position is issued, as in the above-mentioned shift control. When the judgment in step S24 is affirmative, the process proceeds to step S25, and the controller 1 executes the shift. In step S25, the regenerative deceleration downshift is performed by changing the rear gear position Shr from high to low. In the regenerative deceleration downshift, as described later, a decrease in the torque TQmr in absolute value, release of the dog clutch 26r on the high side, rotation synchronization of the dog clutch 26r, engagement of the dog clutch 26r on the low side, and an increase in the torque TQmr in absolute value are performed. After step S25, the process ends.

[0073] If the determination in step S24 is negative, the process proceeds to step S26, where it is determined whether or not the elapsed time is equal to or longer than a predetermined time, as in the above-described shift control. If the determination in step S26 is negative, the process returns to step S24. If the determination in step S26 is positive, the process proceeds to step S27, where the controller 1 operates the rear ACTR 51r to return the rear gear Shr to high. This returns the rear ACTR 51r to its original position before it was operated toward the neutral position. The process ends once after step S27.

[0074] FIG. 19 is a diagram showing an example of a timing chart corresponding to FIG. 18. At timing T41, the vehicle speed VSP becomes equal to or lower than the second predetermined vehicle speed VSP2, and the rear ACTR 51r is operated to the waiting position. As a result, the operating position of the rear ACTR 51r starts to change, and then becomes the waiting position. At timing T42, the vehicle speed VSP becomes equal to or lower than the regenerative deceleration downshift execution vehicle speed VSP_DOWN. As a result, a shift command to the neutral position is issued, and a regenerative deceleration downshift is performed accordingly. In the regenerative deceleration downshift, the torque TQmr starts to decrease in absolute value first in order to release the dog clutch 26r engaged on the high side. In the case of the regenerative deceleration downshift shown by the arrow GS_DOWN described in FIG. 8, the torque TQmf (regenerative torque of the front motor 10f) can be increased in absolute value by the amount of the torque TQmr (regenerative torque of the rear motor 10r) being decreased in absolute value, thereby compensating for the driving force DF. Therefore, in this case, the driving force DF (regenerative driving force) is maintained. At timing T43, the torque TQmr becomes zero, and the release of the dog clutch 26r on the high side starts. As a result, the operating position of the rear ACTR 51r starts to change toward the neutral position. Since the backlash has already been eliminated at timing T43, the operating position of the sleeve 44r starts to change toward the neutral position at timing T43. At timing T44, the release of the dog clutch 26r on the high side is completed, and rotation synchronization starts. The torque TQmr is controlled on the plus side according to the profile at the time of rotation synchronization. Therefore, the rotation speed Nmr starts to increase from timing T44, and the rotation speed of the sleeve 44r is brought closer to the rotation speed Nlr of the drive gear 40r on the low side. The torque TQmf becomes zero at timing T45.

[0075] At timing T45, rotation synchronization is completed. As a result, a shift command to the low position is issued, and engagement of the dog clutch 26r on the low side begins. As a result, the operating position of the rear ACTR 51r begins to change toward the low position. The operating position of the sleeve 44r begins to change toward the low position with a delay according to the backlash. At timing T46, the operating positions of the rear ACTR 51r and the sleeve 44r reach the low position, completing engagement of the dog clutch 26 on the low side. As a result, the torque TQmr begins to increase in absolute value accordingly. At timing T47, the torque TQmr returns to the original torque TQmr, that is, the torque TQmr immediately before the shift, thereby completing the regenerative deceleration downshift.

[0076] In the comparative example shown by the broken line, the rear ACTR 51r is not actuated toward the neutral position at timing T41, and starts to be actuated to the neutral position at timing T43 when the torque TQmr becomes zero. Therefore, the actuation position of the rear ACTR 51r starts to change to the neutral position at timing T43, and the actuation position of the sleeve 44r starts to change to the neutral position from timing T43 with a delay according to the backlash. Therefore, in the present embodiment, the actuation of the rear ACTR 51r is advanced from timing T43 to timing T41, compared to the comparative example, and backlash is eliminated before timing T42 when a shift command is issued. Also, in the comparative example, the actuation of the sleeve 44r is delayed, so that the subsequent shift operation is also delayed, and the regenerative deceleration downshift is completed at timing T48 after timing T47. Therefore, in the present embodiment, the shift completion timing is advanced, and the shift time is shortened, compared to the comparative example. As a result, the time it takes for the front and rear drive force distribution to change (the time it takes to change from four-wheel drive to two-wheel drive) can be shortened, thereby preventing a decrease in driving stability.

[0077] Fig. 20 is a flowchart showing a second example of the third shift control performed by the controller 1. This flowchart is the same as the flowchart shown in Fig. 18, except that step S23B is provided instead of step S23A. Also, in step S23B, the rear ACTR 51r is actuated to the neutral position, as in the second example described above, thereby eliminating backlash.

[0078] FIG. 21 is a diagram showing an example of a timing chart corresponding to FIG. 20. The following mainly describes the parts different from the first example shown in FIG. 19. In the second example, when the vehicle speed VSP reaches the second predetermined vehicle speed VSP2 at timing T51, the rear ACTR 51r starts to move to the neutral position. Also, before a shift command is issued at timing T52, the spring force of the spring 57r eliminates backlash, and when the release force Factrr exceeds the fastening force Fclr, the operating position of the sleeve 44r starts to change to the neutral position. The operating position of the sleeve 44r is in the neutral position at timing T54, delayed from the rear ACTR 51r. After that, rotation synchronization is performed between timing T54 and timing T55, and the dog clutch 26r is fastened on the low side between timing T55 and timing T56, and the torque TQmf increases in absolute value, and the regenerative deceleration downshift is completed at timing T57.

[0079] In the comparative example shown by the broken line, the rear ACTR 51r starts to be operated to the neutral position in response to a shift command at timing T52, which is before timing T53 when the torque TQmr becomes zero. Therefore, in the present embodiment, the operation of the rear ACTR 51r is brought forward from timing T52 to timing T51, compared to the comparative example, so that backlash is eliminated before the shift command is issued at timing T52. In the comparative example, the operation of the sleeve 44r is delayed, so that the subsequent shift operation is also delayed, and the regenerative deceleration downshift is completed at timing T58, which is after timing T57. Therefore, in the present embodiment, the shift completion timing is advanced, and the shift time is shortened compared to the comparative example. As a result, the time during which the front and rear driving force distribution changes can be shortened, thereby suppressing a decrease in driving stability.

[0080] The operating positions of the ACTR 51 in the first to third shift controls described above can be summarized as shown in Figures 22 to 24, which will be described below. Figures 22 to 24 compare the operating positions of the ACTR 51 when the shift mechanism 50 has a standby spring and when it does not have a standby spring.

[0081] As shown in FIG. 22, in the first shift control, when the shift mechanism 50 does not have a waiting spring, the operating position of the front ACTR 51f is controlled from the high position to the waiting position when the accelerator opening APO rises to the predetermined opening APO1. Then, when the accelerator opening APO further rises to the kickdown shift execution opening APO_KD, the operating position is controlled from the waiting position to the neutral position. That is, in this case, backlash is eliminated by operating the front ACTR 51f to the waiting position before the accelerator opening APO becomes the kickdown shift execution opening APO_KD. When the shift mechanism 50 has a waiting spring, the operating position is controlled from the high position to the neutral position when the accelerator opening APO rises to the predetermined opening APO1. That is, in this case, since the shift mechanism 50 has a waiting spring, backlash is eliminated by operating the front ACTR 51f to the neutral position.

[0082] As shown in Fig. 23, in the second gear shift control, when the shift mechanism 50 does not have a standby spring, the operating position of the front ACTR 51f is controlled from the low position to the standby position when the vehicle speed VSP rises to the first predetermined vehicle speed VSP1. Then, when the vehicle speed VSP further rises to the auto upshift execution vehicle speed VSP_UP, the operating position is controlled from the standby position to the neutral position. That is, in this case, backlash is eliminated by operating the front ACTR 51f to the standby position before the vehicle speed VSP becomes the auto upshift execution vehicle speed VSP_UP. When the shift mechanism 50 has a standby spring, the operating position is controlled from the low position to the neutral position when the vehicle speed VSP rises to the first predetermined vehicle speed VSP1, thereby eliminating backlash.

[0083] As shown in Fig. 24, in the third shift control, when the shift mechanism 50 does not have a standby spring, the operating position of the rear ACTR 51r is controlled from the high position to the standby position when the vehicle speed VSP drops to the second predetermined vehicle speed VSP2. Then, when the vehicle speed VSP further drops to the regenerative deceleration downshift execution vehicle speed VSP_DOWN, the operating position is controlled from the standby position to the neutral position. That is, in this case, backlash is eliminated by operating the rear ACTR 51r to the standby position before the vehicle speed VSP becomes the regenerative deceleration downshift execution vehicle speed VSP_DOWN. When the shift mechanism 50 has a standby spring, the operating position is controlled from the high position to the neutral position when the vehicle speed VSP drops to the second predetermined vehicle speed VSP2, thereby eliminating backlash.

[0084] The front motor 10f corresponds to the first drive motor during the kickdown shift and auto upshift described above, and corresponds to the second drive motor during the regenerative deceleration downshift described above. The rear motor 10r corresponds to the second drive motor during the kickdown shift and auto upshift described above, and corresponds to the first drive motor during the regenerative deceleration downshift described above. The same applies to the drive wheels 11, the transmission 16, the dog clutch 26, the ACTR 51, the shift mechanism 50, etc.

[0085] Next, the main effects of this embodiment will be described. The shift control method for the vehicle 100 according to this embodiment is a control method for the vehicle 100, which includes a motor 10 (first drive motor) and a transmission 16 (first transmission) that transmits power between the motor 10 and drive wheels 11 (first drive wheels) and passes through a neutral position during shifting, and the transmission 16 includes an ACTR 51 (first shift actuator) that operates in response to a shift command, and includes operating the ACTR 51 to the neutral position before a shift command is issued to the ACTR 51 during shifting of the transmission 16. According to this method, the shift time can be shortened by operating the ATCR 51 to the neutral position before a shift command is issued. This can improve inconveniences such as a sense of discomfort and a decrease in driving stability that may occur due to a temporary interruption of power transmission.

[0086] The vehicle 100 includes a front motor 10f (first drive motor), a front transmission 16f (first transmission), and a rear motor 10r (second drive motor), and the front transmission 16f includes a front ACTR 51f (first shift actuator). The shift control method for the vehicle 100 further includes compensating for the driving force DF with the rear motor 10r when the front transmission 16f is shifted, and operates the front ACTR 51f toward the neutral position when the required driving force DF_REQ is greater than the maximum driving force of the rear motor 10r (the maximum positive limit driving force DF_LMT2 that can be generated by the rear motor 10r) when the front transmission 16f is shifted. According to this method, in the vehicle 100 configured as a four-wheel drive vehicle, it is possible to suppress discomfort that may occur due to a temporary shortage of the driving force DF, even though the front motor 10f and the rear motor 10r are used as driving sources.

[0087] In the vehicle 100 equipped with the front motor 10f and the front transmission 16f, it is possible to perform a kickdown shift of the front transmission 16f. When performing a kickdown shift of the front transmission 16f, it is not possible to generate a driving force DF according to the accelerator opening APO using the front motor 10f until the downshift is completed. Therefore, if the required driving force DF_REQ is greater than the maximum driving force of the rear motor 10r, a temporary shortage of the driving force DF occurs, resulting in an acceleration lag.

[0088] In this embodiment, when the accelerator opening APO becomes equal to or greater than a predetermined opening APO1 that is lower than the kickdown shift execution opening APO_KD of the front transmission 16f, the front ACTR 51f is operated toward the neutral position. This shortens the shift time of the kickdown shift, thereby suppressing the acceleration lag. As a result, it is possible to suppress the discomfort that may occur due to a temporary lack of driving force DF during the kickdown shift.

[0089] Within the constant output region R2 of the front motor 10f, even if the kickdown shift of the front transmission 16f is performed, an increase in the driving force DF cannot be expected. In this embodiment, when the front motor 10f is operating in the constant torque region R1, the front ACTR 51f is operated toward the neutral position and then the kickdown shift of the front transmission 16f is performed. This allows the first shift control, which is the kickdown shift control, to be performed appropriately.

[0090] A situation in which the driving force DF is temporarily insufficient also occurs during an auto upshift of the front transmission 16f. In this case, the temporary lack of driving force DF causes acceleration hesitation, which makes the driver feel that the acceleration is insufficient. In this embodiment, when the vehicle speed VSP becomes equal to or higher than a first predetermined vehicle speed VSP1 that is lower than the auto upshift execution vehicle speed VSP_UP of the front transmission 16f, the front ACTR 51f is operated toward the neutral position. This shortens the shift time for the auto upshift, thereby suppressing acceleration hesitation. As a result, the discomfort that may occur due to a temporary lack of driving force DF can be suppressed.

[0091] Within the constant torque region R1 of the front motor 10f, the output Pm can be increased by increasing the rotation speed Nmf of the front motor 10f without auto-upshifting the front transmission 16f. Therefore, in this embodiment, when the front motor 10f is operating in the constant output region R2, the front ACTR 51f is operated toward the neutral position and then the front transmission 16f is auto-upshifted. This allows the second gear shift control, which is the auto-upshift control, to be performed appropriately.

[0092] The vehicle 100 includes a rear motor 10r (first drive motor), a rear transmission 16r (first transmission), and a front motor 10f (second drive motor), and the rear transmission 16r includes a rear ACTR 51r (first shift actuator). The shift control method for the vehicle 100 operates the rear ACTR 51r (first shift actuator) toward the neutral position when the vehicle speed VSP becomes equal to or lower than a second predetermined vehicle speed VSP2 that is higher than the regenerative deceleration downshift execution vehicle speed VSP_DOWN of the rear transmission 16r (first transmission). This shortens the shift time for the regenerative deceleration downshift, and therefore shortens the time during which the vehicle 100 is temporarily in two-wheel drive during shifting. As a result, it is possible to suppress a temporary decrease in driving stability.

[0093] In this embodiment, when the fastening force Fcl of the dog clutch 26 (first dog clutch) is greater than the release force Factr of the dog clutch 26 by the ACTR 51 (first shift actuator), the ACTR 51 is actuated toward the neutral position. This makes it possible to prevent the dog clutch 26f from being released against the intention of eliminating backlash even if the ACTR 51 is actuated before a gear shift command is issued.

[0094] When the ACTR 51 is actuated toward the neutral position, the sleeve 44 and the shift fork 54 come into contact with each other, which can cause wear. In this embodiment, if there is no gear shift command to the ACTR 51 even after a predetermined time has elapsed since actuating the ACTR 51 (first shift actuator), the ACTR 51 is returned to its original position before it was actuated toward the neutral position. In other words, in this embodiment, a timeout control for when there is no gear shift command is incorporated into the gear shift control, and the ACTR 51 is returned to its original position when a timeout occurs, so that wear at the contact portion between the sleeve 44 and the shift fork 54 can be reduced.

[0095] The transmission 16 (first transmission) can be configured to have a shift mechanism 50 (first shift mechanism) that transmits the clutch actuation force of an ACTR 51 (first shift actuator) via a spring 57 to a dog clutch 26 (first dog clutch), which is a shift clutch of the transmission 16, that is, a configuration that has a shift mechanism 50 with a standby spring. In this case, when operating the ACTR 51 toward the neutral position, backlash can be eliminated by operating the ACTR 51 to the neutral position, and this allows the shift time of the transmission 16 to be appropriately shortened when the shift mechanism 50 has a standby spring.

[0096] The transmission 16 may be configured to have a shift mechanism 50 that transmits the clutch actuating force of the ACTR 51 to the dog clutch 26 without using any springs, including the spring 57, i.e., a shift mechanism 50 without a standby spring. In this case, when the ACTR 57 is operated toward the neutral position, the ACTR 51 is operated to a standby position according to the backlash between the components of the power transmission path connecting the ACTR 51 and the dog clutch 26, thereby eliminating the backlash. This allows the shift time of the transmission 16 to be appropriately shortened when the shift mechanism 50 does not have a standby spring.

[0097] Second embodiment While the vehicle 100 is traveling, the operating point on the gear shift map shown in FIG. 8 may move from the region R_HH to the region R_LL in the region where the required driving force DF_REQ is negative. In this case, the front transmission 16f and the rear transmission 16r are downshifted, but when they are downshifted simultaneously, they are both in a neutral state. In this case, the required driving force DF_REQ can be satisfied by generating a friction braking force of the drive wheels 11 using the electronically controlled brakes of the vehicle 100. However, in this case, even if the required driving force DF_REQ can be satisfied, regenerative deceleration cannot be performed because both the front transmission 16f and the rear transmission 16r are in a neutral state.

[0098] Therefore, in this case, it is conceivable to change the gears of one of the front transmission 16f and the rear transmission 16r before changing the gears of the other transmission 16. However, in this case, there is a concern that the driving stability may decrease due to a temporary two-wheel drive state as a result of the power being temporarily cut off during the gear change. In consideration of such circumstances, in this embodiment, the controller 1 is configured to further perform a fourth gear change control, which will be described next.

[0099] (Fourth gear shift control) Fig. 25 is a flowchart showing a first example of the fourth gear shift control performed by the controller 1. The fourth gear shift control is a control for shifting the front derailleur 16f and the rear derailleur 16r, and in the fourth gear shift control, one of the front derailleur 16f and the rear derailleur 16r is shifted before the other derailleur 16 is shifted. Fig. 25 shows a case where a regenerative deceleration downshift is performed in which the front derailleur 16f is shifted before the rear derailleur 16r is shifted. Regenerative deceleration can be performed in cases other than when the requested driving force DF_REQ is satisfied by only the frictional braking force out of the driving force DF and the frictional braking force.

[0100] In step S31, the controller 1 judges whether or not a common shifting condition for the front derailleur 16f and the rear derailleur 16r is satisfied. Whether or not the common shifting condition is satisfied can be judged, for example, by whether or not the operating point on the shifting map shown in Fig. 8 moves from the region R_HH to the region R_LL within a predetermined time period in the region where the required driving force DF_REQ is negative. If the judgment in step S31 is negative, the process is temporarily terminated.

[0101] If the determination in step S31 is positive, that is, if the common shifting condition is satisfied, it is determined that the shifting condition for the front transmission 16f, which is to be shifted first, is satisfied. In this case, the process proceeds to step S32, and the controller 1 shifts the front transmission 16f. In step S32, a regenerative deceleration downshift is performed to change the front gear Shf from high to low.

[0102] In step S33, the controller 1 judges whether or not the engagement of the dog clutch 26f is completed. Whether or not the engagement of the dog clutch 26f is completed can be judged based on the operating position of the front ACTR 51f. If the judgment in step S33 is negative, the process returns to step S33. If the judgment in step S33 is positive, the process proceeds to step S34A, and the rear ACTR 51r is operated to the waiting position as in the first example described above. As a result, the backlash in the power transmission path between the rear ACTR 51r and the sleeve 44r is eliminated.

[0103] In step S35, the controller 1 judges whether or not the shifting of the front transmission 16f is completed. Whether or not the shifting of the front transmission 16f is completed can be judged based on the torque TQmf. If the judgment in step S35 is negative, the process returns to step S35. If the judgment in step S35 is positive, it is determined that the shifting conditions of the rear transmission 16r, which will be shifted later, are satisfied. In this case, the process proceeds to step S36, and the controller 1 shifts the rear transmission 16r. In step S36, a regenerative deceleration downshift is performed to change the rear gear Shr from high to low. Then, the regenerative deceleration downshift of the front transmission 16f and the rear transmission 16r is completed by completing the shifting of the rear transmission 16r.

[0104] FIG. 26 is a diagram showing an example of a timing chart corresponding to FIG. 25. The total driving force DFsum indicates the sum of the front driving force DFf and the rear driving force DFr, and the front driving force DFf and the rear driving force DFr are set based on the total driving force DFsum. In this example, the total driving force DFsum is allocated evenly to the front driving force DFf and the rear driving force DFr, and is not allocated to the friction braking force. Therefore, the total driving force DFsum corresponds to the requested driving force DF_REQ. The total driving force DFsum can also be allocated to the friction braking force together with the front driving force DFf and the rear driving force DFr.

[0105] At timing T61, the total driving force DFsum starts to decrease in response to the start of the decrease in the accelerator opening APO, and at timing T62, the driver starts braking. As a result, a negative requested driving force DF_REQ is generated in response to the amount of depression of the brake pedal, and the total driving force DFsum becomes a negative value. At timing T63, the common shifting condition is satisfied. As a result, the front side shifting condition, that is, the shifting condition of the front transmission 16f, is satisfied. Therefore, at timing T63, the front driving force DFf starts to decrease in absolute value toward zero in order to release the engagement of the dog clutch 26f on the high side. In response to this, the rear driving force DFr starts to increase in absolute value, and the driving force DF is compensated for. The front driving force DFf becomes zero at timing T64. As a result, a front side shifting command, that is, a shifting command for the front transmission 16f, is issued, and the release of the dog clutch 26f on the high side begins. Therefore, as shown in the front side operating position, the operating position of the front ACTR 51f starts to move toward the neutral position, and the operating position of the sleeve 44f starts to move toward the neutral position with a delay corresponding to the backlash. After that, when the operating position of the sleeve 44f reaches the neutral position, the rotation synchronization of the dog clutch 26f starts. Also, when the rotation synchronization of the dog clutch 26f is completed, a front side shift command to the low position is issued, and the engagement of the dog clutch 26f on the low side starts. Therefore, the operating position of the front ACTR 51f starts to change toward the low position, and the operating position of the sleeve 44f starts to change toward the low position with a delay corresponding to the backlash.

[0106] At timing T65, the operating position of the sleeve 44f becomes the low position, and the engagement of the dog clutch 26f is completed. At timing T65, the rear driving force DFr is not zero, and the engagement force Fclr of the dog clutch 26r is greater than the release force Factrr. Therefore, at timing T65, the rear ACTR 51r starts to move to the waiting position, and the operating positions of the rear ACTR 51r and the sleeve 44r start to change toward the waiting position. The operating positions of the rear ACTR 51r and the sleeve 44r become the waiting position before timing T67 when a rear side shift command to the neutral position, i.e., a shift command for the rear derailleur 16r, is issued.

[0107] From timing T65, the front motor 10f controls the front driving force DFf to return to the original front driving force DFf before the front derailleur 16f shifts, that is, the front driving force DFf immediately before timing T63. Also, the rear motor 10r controls the rear driving force DFr to return to the original rear driving force DFr before the front derailleur 16f shifts. The front driving force DFf and the rear driving force DFr are each returned to the original driving force DF at timing T66. As a result, the shifting of the front derailleur 16f is completed, and based on this, the rear side shifting condition, that is, the shifting condition of the rear derailleur 16r, is established. Therefore, from timing T66, in order to release the engagement of the dog clutch 26r on the high side, the rear driving force DFr starts to decrease in absolute value toward zero. Also, the front driving force DFf starts to increase in absolute value, thereby compensating for the driving force DF.

[0108] At time T67, the rear driving force DFr becomes zero, and a rear shift command to the neutral position is issued. As a result, the operating positions of the rear ACTR 51r and the sleeve 44r start to change from the standby position toward the low position. After that, the dog clutch 26r undergoes rotation synchronization, and when the operating position of the sleeve 44r reaches the low position at time T68, engagement of the dog clutch 26r is completed. Also, when the driving force DF returns to the original driving force DF before the rear derailleur 16r shift at time T69, the shift of the rear derailleur 16r is completed.

[0109] The changes indicated by the symbol C1 are in the case of the first comparative example. The first comparative example shows a case where the front derailleur 16f and the rear derailleur 16r are shifted simultaneously based on a common shifting condition. Therefore, in this case, when the common shifting condition of the vehicle speed VSP is satisfied at timing T63, not only the front shifting condition but also the rear shifting condition is satisfied, and the front driving force DFf and the rear driving force DFr are both reduced in absolute value toward zero. Also, when the front driving force DFf and the rear driving force DFr become zero at timing T64, not only the front side shifting command but also the rear side shifting command is issued. As a result, not only the operating position of the sleeve 44f but also the operating position of the sleeve 44r starts to change toward the neutral position with a delay according to the backlash. The shift is then completed at timing T66 through rotation synchronization. In the first comparative example, the required driving force DF_REQ can be satisfied by the frictional braking force of the electronically controlled brake between timing T64 and timing T65 when the driving force DF becomes zero. In this case, however, even though the regenerative driving force of the single motor 10 can satisfy the required driving force DF_REQ, regenerative deceleration cannot be performed.

[0110] In this embodiment, the front derailleur 16f is shifted based on a common shifting condition, and then the rear derailleur 16r is shifted. This avoids a situation in which both the front derailleur 16f and the rear derailleur 16r are in a neutral state, and when one derailleur 16 is shifted, the motor 10 of the other derailleur 16 can perform regenerative deceleration. In this embodiment, the operating position of the sleeve 44f of the front derailleur 16f, which is shifted first, remains in the low position from timing T65. Therefore, even if the sleeve 44r is operated beyond the waiting position to the neutral position, both the front derailleur 16f and the rear derailleur 16r will not be in a neutral state.

[0111] The changes indicated by the symbol C2 are those in the second comparative example. As in the present embodiment, the second comparative example shows a case in which the front derailleur 16f is shifted and then the rear derailleur 16r is shifted, but without removing backlash. Thus, in the second comparative example, the rear ACTR 51r starts to be operated from the high position to the neutral position at timing T67 when a rear side shift command to the neutral position is issued, and the operating position of the sleeve 44r starts to change to the neutral position with a delay corresponding to the backlash relative to the rear ACTR 51r. As a result, a delay also occurs in the subsequent shift operation, and the shift is completed at timing T70, which is later than timing T69.

[0112] In the present embodiment, the operating position of the sleeve 44r is in the waiting position at timing T67. Therefore, the timing at which the operating position of the sleeve 44r becomes the neutral position is earlier than in the second comparative example by the amount of backlash eliminated. As a result, the subsequent gear shifting operation is also earlier than in the second comparative example, and the gear shifting is completed at timing T69. Therefore, in the present embodiment, the gear shifting time of the rear transmission 16r is shorter than in the second comparative example, and the time during which the vehicle 100 is temporarily in two-wheel drive state is shorter, thereby suppressing a decrease in driving stability.

[0113] Fig. 27 is a flowchart showing a second example of the fourth gear shift control performed by the controller 1. This flowchart is the same as the flowchart shown in Fig. 25 except that step S34B is provided instead of step S34A. Also, in step S34B, the rear ACTR 51r is actuated to the neutral position as in the second example described above.

[0114] Fig. 28 is a diagram showing an example of a timing chart corresponding to Fig. 27. The following mainly describes the differences from the timing chart shown in Fig. 26. In the second example, when the engagement of the dog clutch 26f is completed at timing T75, the operation of the rear ACTR 51r to the neutral position is started. Also, before the rear side shift command to the neutral position is issued at timing T77, the backlash is eliminated by the spring force of the spring 57r, and then when the release force Factrr exceeds the engagement force Fclr, the operating position of the sleeve 44r starts to change to the neutral position side.

[0115] In this case, unlike the first comparative example indicated by the symbol C1, the front derailleur 16f is shifted before the rear derailleur 16r is shifted, so that regenerative deceleration can be performed by the rear motor 10r when the front derailleur 16f is shifted. In addition, since the sleeve 44f of the front derailleur 16f, which is shifted first, remains in the low position from the timing T75, even if the rear ACTR 51r is operated to the neutral position, both the front derailleur 16f and the rear derailleur 16r do not enter the neutral state. In this case, before the rear side shift command to the neutral position is issued at the timing T77, the backlash is eliminated by the spring force of the spring 57r. Therefore, the operating position of the sleeve 44r reaches the neutral position earlier than in the second comparative example. As a result, the subsequent shift operation is also earlier than in the second comparative example, and the shift is completed earlier than in the second comparative example. Therefore, the shift time of the rear transmission 16r is shorter than in the second comparative example, and the time during which the vehicle 100 is temporarily in the two-wheel drive state is shortened accordingly, thereby suppressing a decrease in driving stability.

[0116] Next, the main effects of this embodiment will be described. In this embodiment, the vehicle 100 is configured to include a rear motor 10r (first motor) and a rear transmission 16r (first transmission), and a front motor 10f (second motor) and a front transmission 16f (second transmission), and the rear transmission 16r is configured to include a rear ACTR 51r (first shift actuator). In this embodiment, when the rear transmission 16r and the front transmission 16f are downshifted for regenerative deceleration, the front transmission 16f is shifted first, and then the rear transmission 16r is shifted, and the rear ACTR 51r is operated to the neutral position side after the timing when the engagement of the dog clutch 26f (second mesh clutch), which is the shift clutch of the front transmission 16f, is completed.

[0117] In other words, in this embodiment, the front transmission 16f is shifted before the rear transmission 16r is shifted, so that it is possible to avoid a situation in which the front transmission 16f and the rear transmission 16r are both in a neutral state, making it impossible to perform a regenerative deceleration downshift. Furthermore, since the rear ACTR 51r is operated toward the neutral position after the timing at which the engagement of the dog clutch 26f is completed, the shift time of the rear transmission 16r can be shortened. As a result, the time during which the vehicle 100 is temporarily in a two-wheel drive state can be shortened, and a decrease in driving stability can be suppressed.

[0118] The fourth shift control can also be applied to an auto-upshift. In this case, in step S31 of FIG. 25 and FIG. 27, for example, by determining whether the operating point on the shift map shown in FIG. 8 has moved from the region R_LL to the region R_HH within a predetermined time in the region where the requested driving force DF_REQ is positive, it is possible to determine whether the common shift condition is satisfied. In this case, it is possible to change so that the front transmission 16f is upshifted in step S32 and the rear transmission 16r is upshifted in step S36. In this case, the front transmission 16f and the rear transmission 16r are both in a neutral state, resulting in a significant shortage of driving force DF, and thus it is possible to prevent the driver from feeling uncomfortable, and also to prevent the driver from feeling uncomfortable by shortening the shift time of the transmission 16 that is shifted later.

[0119] The rear derailleur 16r may be configured to have a shift mechanism 50r (first shift mechanism) that transmits the clutch actuation force of the rear ACTR 51r to the dog clutch 26r (first dog clutch) that is the shift clutch of the rear derailleur 16r via a spring 57r, that is, a shift mechanism 50r with a waiting spring. The rear derailleur 16r may also be configured to have a shift mechanism 50r that transmits the clutch actuation force of the rear ACTR 51r to the dog clutch 26r without using springs including the spring 57, that is, a shift mechanism 50r without a waiting spring. In these cases, the shift time of the rear derailleur 16r can be appropriately shortened by eliminating backlash in the same manner as described above in the first embodiment.

[0120] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

[0121] In the above embodiment, the vehicle 100 is a four-wheel drive vehicle equipped with a front motor 10f and a front transmission 16f, and a rear motor 10r and a rear transmission 16r. However, as shown in FIG. 29, the vehicle 100 may be a four-wheel drive vehicle equipped with a front motor 10f and a front transmission 16f, but also equipped with a rear motor 10r that transmits power to the rear drive wheels 11r without passing through a transmission including the rear transmission 16r. Alternatively, as shown in FIG. 30, the vehicle 100 may be a four-wheel drive vehicle equipped with a rear motor 10r and a rear transmission 16r, but also equipped with a front motor 10f that transmits power to the front drive wheels 11f without passing through a transmission including the front transmission 16f. Even in these cases, the shift time can be shortened by at least one of the first to third shift controls, and inconveniences that may occur due to a temporary interruption of power transmission can be improved.

[0122] Furthermore, the vehicle 100 may be a two-wheel drive vehicle, i.e., a front-wheel drive vehicle, equipped with a front motor 10f and a front transmission 16f, as shown in Fig. 31. Alternatively, the vehicle 100 may be a two-wheel drive vehicle, i.e., a rear-wheel drive vehicle, equipped with a rear motor 10r and a rear transmission 16r, as shown in Fig. 32. Even in these cases, the shift time can be shortened by operating the ACTR 51 to the neutral position before a shift command is issued to the ACTR 51 when shifting the transmission 16. This can improve the inconvenience that may occur due to a temporary interruption of the power transmission. [Explanation of symbols]

[0123] 1 Controller (control section) 26f Dog clutch (first or second dog clutch) 26r Dog clutch (2nd or 1st dog clutch) 10f Front motor (first or second drive motor) 10r Rear motor (second or first drive motor) 11f Front drive wheels (first or second drive wheels) 11r Rear drive wheel (2nd or 1st drive wheel) 16f Front derailleur (1st or 2nd derailleur) 16r Rear derailleur (2nd or 1st derailleur) 50f Shift mechanism (first or second shift mechanism) 50r Shift mechanism (second or first shift mechanism) 51f Front ACTR (1st or 2nd shift actuator) 51r Rear ACTR (2nd or 1st shift actuator) 57 Spring 100 vehicles

Claims

1. A method for controlling gear shifting of a vehicle including a first drive motor and a first transmission that transmits power between the first drive motor and first drive wheels and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command, when an engagement force of a first mesh clutch, which is a shift clutch of the first transmission, is greater than a release force of the first mesh clutch by the first shift actuator, actuating the first shift actuator toward the neutral position before the shift command is given to the first shift actuator during shifting of the first transmission; A vehicle speed change control method comprising:

2. 2. A vehicle shift control method according to claim 1, comprising: The vehicle further includes a second drive motor that transmits power to a second drive wheel. The method further includes supplementing driving force by the second drive motor when the first transmission is shifted. when a required driving force during a gear shift of the first transmission becomes larger than a maximum driving force of the second drive motor, the first shift actuator is actuated toward the neutral position before the gear shift command is given to the first shift actuator during a gear shift of the first transmission; A vehicle speed change control method comprising:

3. 3. A vehicle shift control method according to claim 2, comprising: When an accelerator opening degree becomes equal to or greater than a predetermined opening degree that is lower than a kickdown shift execution opening degree of the first transmission, the first shift actuator is actuated toward the neutral position. A vehicle speed change control method comprising:

4. 4. A vehicle speed change control method according to claim 3, comprising: When the first drive motor is operating in a constant torque region, before the gear shift command is issued to the first shift actuator, the first shift actuator is operated toward the neutral position side and then the first transmission is shifted. A vehicle speed change control method comprising:

5. 3. A vehicle shift control method according to claim 2, comprising: when the vehicle speed becomes equal to or higher than a first predetermined vehicle speed that is lower than an auto upshift execution vehicle speed of the first transmission, actuating the first shift actuator toward the neutral position; A vehicle speed change control method comprising:

6. 6. A vehicle speed change control method according to claim 5, When the first drive motor is operating in a constant output region, before the shift command is issued to the first shift actuator, the first shift actuator is operated toward the neutral position side and then the first transmission is shifted. A vehicle speed change control method comprising:

7. 2. A vehicle shift control method according to claim 1, comprising: The vehicle further includes a second drive motor that transmits power to a second drive wheel. When the vehicle speed becomes equal to or lower than a second predetermined vehicle speed that is higher than a regenerative deceleration downshift execution vehicle speed of the first transmission, the first shift actuator is actuated toward the neutral position. A vehicle speed change control method comprising:

8. A vehicle speed change control method according to claim 1, 2 or 5, comprising: when the first shift actuator is not commanded to shift gears even after a predetermined time has elapsed since the first shift actuator was operated, the first shift actuator is returned to its original position before being operated toward the neutral position. A vehicle speed change control method comprising:

9. 2. A vehicle shift control method according to claim 1, comprising: The vehicle further includes a second drive motor and a second transmission that transmits power between the second drive motor and second drive wheels and passes through a neutral position during gear shifting. When shifting the first transmission and the second transmission, the second transmission is shifted first and then the first transmission is shifted, and after a timing when engagement of a second mesh clutch, which is a shift clutch of the second transmission, is completed, during shifting of the first transmission, the first shift actuator of the first transmission is operated toward the neutral position before the shift command is given to the first shift actuator. A vehicle speed change control method comprising:

10. A vehicle speed change control method according to claim 1, 2, 5 or 9, comprising: the first transmission has a first shift mechanism that transmits a clutch actuation force of the first shift actuator to a first dog clutch that is a shift clutch of the first transmission via a spring; When the first transmission is shifted, before the shift command is given to the first shift actuator, the first shift actuator is operated toward the neutral position by operating the first shift actuator to the neutral position. A vehicle speed change control method comprising:

11. A vehicle speed change control method according to claim 1, 2, 5 or 9, comprising: the first transmission has a first shift mechanism that transmits a clutch actuation force of the first shift actuator to a first dog clutch that is a shift clutch of the first transmission without using a spring; When the first transmission is shifted, before the first shift actuator is instructed to shift the gears, the first shift actuator is operated to a waiting position corresponding to a backlash between components of a power transmission path connecting the first shift actuator and the first dog clutch, in order to operate the first shift actuator toward the neutral position. A vehicle speed change control method comprising:

12. A gear shift control device for a vehicle including a first drive motor, and a first transmission that transmits power between the first drive motor and a first drive wheel and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command, and a control unit that, when an engagement force of a first mesh clutch, which is a shift clutch of the first transmission, is greater than a release force of the first mesh clutch by the first shift actuator, operates the first shift actuator to the neutral position side before the shift command is issued to the first shift actuator during shifting of the first transmission. A vehicle shift control device comprising:

13. A method for controlling gear shifting of a vehicle including a first drive motor and a first transmission that transmits power between the first drive motor and first drive wheels and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command, The vehicle further includes a second drive motor that transmits power to a second drive wheel. supplementing driving force with the second drive motor when the first transmission is shifted; when a required driving force during a gear shift of the first transmission becomes larger than a maximum driving force of the second drive motor, actuating the first shift actuator toward the neutral position before the gear shift command is issued to the first shift actuator during a gear shift of the first transmission; A vehicle speed change control method comprising:

14. A method for controlling gear shifting of a vehicle including a first drive motor and a first transmission that transmits power between the first drive motor and first drive wheels and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command, the first transmission has a first shift mechanism that transmits a clutch actuating force of the first shift actuator to a first dog clutch that is a shift clutch of the first transmission via a standby spring; During a gear shift of the first transmission, before the gear shift command is issued to the first shift actuator, the first shift actuator is actuated toward the neutral position. When operating the first shift actuator toward the neutral position before the shift command is given to the first shift actuator during a gear shift of the first transmission, the first shift actuator is operated to the neutral position; A vehicle speed change control method comprising:

15. A method for controlling gear shifting of a vehicle including a first drive motor and a first transmission that transmits power between the first drive motor and first drive wheels and passes through a neutral position during gear shifting, the first transmission including a first shift actuator that operates in response to a gear shift command, the first transmission has a first shift mechanism that transmits a clutch actuation force of the first shift actuator to a first dog clutch that is a shift clutch of the first transmission without using a spring; During a gear shift of the first transmission, before the gear shift command is issued to the first shift actuator, the first shift actuator is actuated toward the neutral position. When operating the first shift actuator toward the neutral position before the shift command is issued to the first shift actuator during a gear shift of the first transmission, the first shift actuator is operated to a waiting position corresponding to a backlash between components of a power transmission path connecting the first shift actuator and the first dog clutch. A vehicle speed change control method comprising:

Images