The disclosure of Japanese Patent Application No. 2016-084068 filed on Apr. 19, 2016 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The disclosure relates to a hybrid vehicle, and a control method for the hybrid vehicle. In particular, the disclosure is concerned with a hybrid vehicle including an electric continuously variable transmission and a mechanical stepwise variable transmission that are arranged in series.
A vehicle is known which has an electric continuously variable speed change unit that can steplessly change the rotational speed of a drive source through torque control of a differential rotating machine, and transmit resulting rotation to an intermediate transmission member, and a mechanical stepwise variable speed change unit that is disposed between the intermediate transmission member and drive wheels, and can mechanically establish a plurality of gear positions having different speed ratios of the rotational speed of the intermediate transmission member to the output rotational speed. A hybrid vehicle described in Japanese Patent Application Publication No. 2006-321392 (JP 2006-321392 A) is one example of this type of vehicle. According to a technology described in JP 2006-32192 A, in order to curb occurrence of shift shock due to change of the rotational speed in the inertia phase, during shifting of the mechanical stepwise variable speed change unit, the speed ratio of the electric continuously variable speed change unit is changed while the rotational speed of the drive source is kept substantially constant, so as to start the inertia phase of the mechanical stepwise variable speed change unit.
However, it is difficult to completely prevent shift shock even in the shift control system as described above, and even a slight shock may cause the driver to feel strange or uncomfortable since the rotational speed of the drive source is substantially constant.
This disclosure is to further reduce the feeling of strangeness of the driver caused by shift shock during shifting of a mechanical stepwise variable transmission, in a vehicle having an electric continuously variable transmission and the mechanical stepwise variable transmission.
A first aspect of the disclosure is a hybrid vehicle. The hybrid vehicle includes an electric continuously variable transmission, a mechanical stepwise variable transmission, and an electronic control unit. The electric continuously variable transmission is configured to steplessly change a rotational speed of a drive source through torque control of a differential rotating machine, and transmit resulting rotation to an intermediate transmission member. The mechanical stepwise variable transmission is disposed between the intermediate transmission member and drive wheels. The mechanical stepwise variable transmission is configured to establish a plurality of mechanical gear positions having different speed ratios of a rotational speed of the intermediate transmission member to an output rotational speed of the mechanical stepwise variable transmission. The mechanical gear positions are mechanically established by the mechanical stepwise variable transmission. The electronic control unit is configured to control the electric continuously variable transmission so as to establish a plurality of virtual gear positions having different speed ratios of the rotational speed of the drive source to the output rotational speed of the mechanical stepwise variable transmission. The number of speeds of the plurality of virtual gear positions is equal to or larger than the number of speeds of the plurality of mechanical gear positions, and at least one of the virtual gear positions is assigned to each of the mechanical gear positions. The electronic control unit is configured to control the electric continuously variable transmission so as to shift the electric continuously variable transmission from one of the virtual gear positions to another according to predetermined shift conditions. Shift conditions of the plurality of mechanical gear positions being determined such that the mechanical stepwise variable transmission is shifted from one of the mechanical gear positions to another in the same timing as shift timing of the virtual gear positions.
In the hybrid vehicle, the electronic control unit may be configured to limit a shift range of the virtual gear positions, such that a specified virtual gear position is set to an upper limit of the shift range, when any of the mechanical gear positions of the mechanical stepwise variable transmission is not established. The specified virtual gear position is a virtual gear position assigned to one of the mechanical gear positions which is lower by one speed than the mechanical gear position that is not established.
A second aspect of the disclosure is a control method for a hybrid vehicle. The hybrid vehicle includes an electric continuously variable transmission, a mechanical continuously variable transmission, and an electronic control unit. The electric continuously variable transmission is configured to steplessly change a rotational speed of a drive source through torque control of a differential rotating machine, and transmit resulting rotation to an intermediate transmission member. The mechanical stepwise variable transmission is disposed between the intermediate transmission member and drive wheels. The mechanical stepwise variable transmission is configured to establish a plurality of mechanical gear positions having different speed ratios of a rotational speed of the intermediate transmission member to an output rotational speed of the mechanical stepwise variable transmission. The mechanical gear positions are mechanically established by the mechanical stepwise variable transmission. The control method includes controlling, by the electronic control unit, the electric continuously variable transmission so as to establish a plurality of virtual gear positions having different speed ratios of the rotational speed of the drive source to the output rotational speed of the mechanical stepwise variable transmission. The number of speeds of the plurality of virtual gear positions is equal to or larger than the number of speeds of the plurality of mechanical gear positions, and at least one of the virtual gear positions is assigned to each of the mechanical gear positions. The control method further includes controlling, by the electronic control unit, the electric continuously variable transmission so as to shift the electric continuously variable transmission from one of the virtual gear positions to another according to predetermined shift conditions. Shift conditions of the plurality of mechanical gear positions being determined such that the mechanical stepwise variable transmission is shifted from one of the mechanical gear positions to another in the same timing as shift timing of the virtual gear positions.
Features, advantages, and technical and industrial significance of exemplary embodiments will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
Next, the configuration of this disclosure will be described.
As a drive source of a hybrid vehicle, an engine, such as an internal combustion engine that generates power by burning fuel, an electric motor, or the like, is favorably used. While an electric continuously variable transmission has a differential mechanism, such as a planetary gear unit, it may use a paired-rotor electric motor having an inner rotor and an outer rotor. When the paired-rotor motor is used as the electric continuously variable transmission, the drive source is connected to one of the inner rotor and the outer rotor, and an intermediate transmission member is connected to the other rotor. Like a motor-generator, the paired-rotor motor can selectively deliver power running torque and regenerative torque, and also functions as a rotating machine for differential operation (which will be called “differential rotating machine”). The drive source and the intermediate transmission member are connected to the differential mechanism, or the like, via a clutch or a speed change gear, as needed. A rotating machine for driving the vehicle for traveling (which will be called “driving rotating machine”) is connected to the intermediate transmission member directly or via a speed change gear, or the like, as needed.
As the differential mechanism of the electric continuously variable transmission, a single planetary gear unit of a single pinion type or double pinion type is favorably used. The planetary gear unit includes three rotating elements, i.e., a sun gear, a carrier, and a ring gear. In a nomographic chart in which respective rotational speeds of the three rotating elements can be connected by a single straight line, the drive source is connected to a rotating element (the carrier of the single pinion type planetary gear unit, or the ring gear of the double pinion type planetary gear unit) located at the middle in the chart and having a middle rotational speed, and the differential rotating machine and the intermediate transmission member are connected to the rotating elements at the opposite ends in the chart, for example. The intermediate transmission member may be connected to the middle rotating element, and the differential rotating machine and the drive source may be connected to the rotating elements at the opposite ends. While the three rotating elements may be differentially rotatable at all times, any two of the rotating elements may be integrally connected by a clutch, such that they can rotate as a unit according to operating conditions. Also, differential rotation of the three rotating elements may be restricted by stopping rotation of the rotating element to which the differential rotating machine is connected, by means of a brake. Further, a differential mechanism as a combination of two or more planetary gear units may be employed as the electric continuously variable transmission.
The rotating machine, which means a rotating electric machine, is specifically an electric motor, a generator, or a motor-generator that can selectively use the functions of the motor and the generator. Motor-generators may be used as both the differential rotating machine, and the driving rotating machine. A generator may be employed as the differential rotating machine, and an electric motor may be employed as the driving rotating machine.
As a mechanical stepwise variable transmission, a transmission of a planetary gear type or parallel shaft type is widely used. In the transmission, two or more hydraulic friction devices are engaged and released, for example, so that a plurality of gear positions (mechanical gear positions) can be established. While the mechanical gear positions appropriately provide forward gear positions, they may provide backward gear positions.
The electric continuously variable transmission and the mechanical stepwise variable transmission are controlled by an electronic control unit, so that a plurality of virtual gear positions can be established. The virtual gear positions are established by controlling the rotational speed of the drive source according to the output rotational speed such that the speed ratio of each gear position can be maintained. The speed ratio of each of the virtual gear positions need not be a constant value like those of the mechanical gear positions of the mechanical stepwise variable transmission, but may be changed within a given range. Further, the speed ratio of each virtual gear position may be limited by the upper limit or lower limit of the rotational speed of each part, for example. For example, shift conditions of the virtual gear positions may be defined by using a shift map of upshift lines and downshift lines determined in advance based on operating conditions of the vehicle, such as the output rotational speed and the accelerator operation amount, as parameters. In this connection, automatic shift conditions other than the shift map may be set as the shift conditions of the virtual gear positions, or the virtual gear position may be changed or shifted according to a shift command of the driver, by use of a shift lever or an UP/DOWN switch, for example. While it is desirable that this disclosure is applied to both upshifts and downshifts, it may only be applied to either of upshifts and downshifts. Namely, virtual stepwise shifts using the virtual gear positions may be performed as one of the upshifts and the downshifts, and stepless speed changes similar to conventional ones may be performed as the other.
The number of speeds of the virtual gear positions may be equal to or larger than the number of speeds of the mechanical gear positions. While the number of speeds of the virtual gear positions may be equal to that of the mechanical gear positions, it is desirable that the number of speeds of the virtual gear positions is larger than that of the mechanical gear positions, and it is appropriately equal to or larger than twice the number of speeds of the mechanical gear positions. Shifts of the mechanical gear positions are performed such that the rotational speed of the intermediate transmission member or the driving rotating machine connected to the intermediate transmission member is held within a given rotational speed range. Meanwhile, shifts of the virtual gear positions are performed such that the rotational speed of the drive source is held within a given rotational speed range. Accordingly, while the number of speeds of the mechanical gear positions and the number of speeds of the virtual gear positions are determined as appropriate, the number of speeds of the mechanical gear positions is appropriately within the range of about two speeds to six speeds, for example, while the number of speeds of the virtual gear positions is appropriately within the range of five speeds to twelve speeds, for example.
When any of the mechanical gear positions cannot be established, the electronic control unit limits the shift range of the virtual gear positions, such that the virtual gear position assigned to the mechanical gear position that is lower by one speed than the mechanical gear position that cannot be established is set to the upper limit. However, the electronic control unit may include the virtual gear position(s) assigned to the mechanical gear position that cannot be established, within the shift permissible range, as long as the rotational speed of the intermediate transmission member or the driving rotating machine does not become excessively high. Namely, shift control may be performed using all of the virtual gear positions, irrespective of restriction of the mechanical gear positions. In this case, when the mechanical gear position that has been unable to be established due to a low oil temperature, for example, becomes able to be established due to increase of the oil pressure, shock and uncomfortable feeling given to the driver can be further reduced when the electronic control unit returns to normal shift control, including that of the mechanical stepwise variable transmission. When any of the mechanical gear positions cannot be established due to a failure of a solenoid valve for shifting, virtual stepwise shifts using the virtual gear positions may be inhibited and switched to stepless speed change. When the virtual stepwise shifts are inhibited and switched to the stepless speed change, the rotational speed of the drive source is less likely or unlikely to be restricted, as compared with the virtual stepwise shifts; therefore, power performance needed for limp-home traveling can be appropriately ensured. Thus, it may be determined whether the virtual stepwise shifts are continued or switched to stepless speed change, depending on the cause of the failure to establish the mechanical gear position.
One embodiment of the disclosure will be described in detail with reference to the drawings.
The electric continuously variable transmission 16 includes a first motor-generator MG1 for differential operation, a differential mechanism 24, and a second motor-generator MG2 for running or driving the vehicle. The differential mechanism 24 is configured to mechanically distribute the output or power of the engine 14 to the first motor-generator MG1 and the intermediate transmission member 18. The second motor-generator MG2 is operatively connected to the intermediate transmission member 18 so as to rotate as a unit with the member 18. Each of the first motor-generator MG1 and the second motor-generator MG2 can be selectively used as an electric motor or a generator. The first motor-generator MG1 corresponds to the differential rotating machine, and the second motor-generator MG2 corresponds to the driving rotating machine. The vehicular drive system 10 of this embodiment is concerned with a hybrid vehicle including the engine 14 and the second motor-generator MG2 as drive sources for running the vehicle.
The differential mechanism 24 is in the form of a single pinion type planetary gear unit, and includes a sun gear S0, a carrier CA0, and a ring gear R0. The carrier CA0 is a first rotating element connected to the engine 14 via a connecting shaft 36. The sun gear S0 is a second rotating element connected to the first motor-generator MG1. The ring gear R0 is a third rotating element connected to the intermediate transmission member 18. In other words, in a nomographic chart of the electric continuously variable transmission 16 shown on the left side in
The mechanical stepwise variable transmission 20 provides a part of a power transmission path between the engine 14 and the drive wheels 34, and is a planetary gear type, multiple-speed transmission having a single pinion type first planetary gear unit 26 and a single pinion type second planetary gear unit 28. The first planetary gear unit 26 includes a sun gear 51, a carrier CA1, and a ring gear R1. The second planetary gear unit 28 includes a sun gear S2, a carrier CA2, and a ring gear R2. The sun gear 51 is selectively connected to the case 12 via a first brake B1. The sun gear S2 is selectively connected to the intermediate transmission member 18 via a first clutch C1. The carrier CA1 and the ring gear R2 are connected integrally with each other, and are selectively connected to the intermediate transmission member 18 via a second clutch C2. The carrier CA1 and the ring gear R2 are selectively connected to the case 12 via a second brake B2. The carrier CA1 and the ring gear R2 are connected to the case 12 as a non-rotating member via a one-way clutch F1, so as to be allowed to rotate in the same direction as the engine 14 but inhibited from rotating in the reverse direction. The ring gear R1 and the carrier CA2 are connected integrally with each other, and are connected integrally to the output shaft 22.
With the clutches C1, C2 and the brakes B1, B2 (which will be simply referred to as “clutches C” and “brakes B” when they are not particularly distinguished) selectively engaged, the mechanical stepwise variable transmission 20 is placed in a selected one of a plurality of forward gear positions having different speed ratios γ2 (=Nm/Nout) of the intermediate transmission member rotational speed Nm to the rotational speed (output rotational speed) Nout of the output shaft 22. The forward gear positions correspond to the mechanical gear positions that are mechanically established. As shown in the engaging operation table of
The clutches and the brakes B are multi-plate or single-plate type hydraulic friction devices that are frictionally engaged by hydraulic pressure.
Linear solenoid valves SL1-SL4 as hydraulic control devices are provided for respective hydraulic actuators (hydraulic cylinders) 50, 52, 54, 56 of the clutches C1, C2 and the brakes B1, B2. The linear solenoid valves SL1-SL4 are independently energized and de-energized by the electronic control unit 60. With the hydraulic pressures of the respective hydraulic actuators 50, 52, 54, 56 thus independently regulated and controlled, engagement and release of the clutches C1, C2 and the brakes B1, B2 are individually controlled, so that the mechanical 1st-speed gear position through the mechanical 4th-speed gear position are established. Also, in shift control of the mechanical stepwise variable transmission 20, clutch-to-clutch shift is performed. The clutch-to-clutch shift is shift control under which release and engagement of selected ones of the clutches C and brakes B which are associated with the shift are controlled at the same time. For example, on a 3→2 downshift from the mechanical 3rd-speed gear position to the mechanical 2nd-speed gear position, the second clutch C2 is released, and the first brake B1 is engaged at the same time, as indicated in the engaging operation table of
The vehicular drive system 10 includes an electronic control unit 60 as a controller that performs output control of the engine 14, and shift control of the electric continuously variable transmission 16 and the mechanical stepwise variable transmission 20. The electronic control unit 60 includes a microcomputer having CPU, ROM, RAM, input/output interface, and so forth. The electronic control unit 60 performs signal processing according to programs stored in advance in the ROM, while utilizing the temporary storage function of the RAM. The electronic control unit 60 may include two or more electronic control units for use in engine control, shift control, etc. as needed. The electronic control unit 60 receives various kinds of information needed for control, such as the amount of operation of the accelerator pedal (accelerator operation amount) Acc, output rotational speed Nout, engine speed Ne, MG1 rotational speed Ng, and the MG2 rotational speed Nm, from an accelerator operation amount sensor 62, output rotational speed sensor 64, engine speed sensor 66, MG1 rotational speed sensor 68, MG2 rotational speed sensor 70, and so forth. The output rotational speed Nout corresponds to the vehicle speed V.
The electronic control unit 60 functionally includes a mechanical shift controller 80, a hybrid controller 82, and a virtual shift controller 84. The mechanical shift controller 80 makes a shift determination for the mechanical stepwise variable transmission 20, according a predetermined mechanical gear position shift map, using the output rotational speed Nout and the accelerator operation amount Acc as parameters, and changes engaged/released states of the clutches C and the brakes B as needed by means of the linear solenoid valves SL1-SL4, so as to automatically change the mechanical gear position of the mechanical stepwise variable transmission 20. The mechanical gear position shift map is determined such that the MG2 rotational speed Nm as the rotational speed of the intermediate transmission member 18 and the second motor-generator MG2 is held within a given rotational speed range. The mechanical gear position shift map is stored in advance in a data storage unit 90.
The hybrid controller 82 operates the engine 14 in an operating range having a high fuel efficiency, and performs stepless shift control for steplessly changing the speed ratio γ1 of the electric continuously variable transmission 16. The stepless shift control is performed by controlling the proportion of driving force between the engine 14 and the second motor-generator MG2 and reaction force produced through power generation of the first motor-generator MG1, so as to steplessly change the speed ratio γ1 of the electric continuously variable transmission 16. For example, the hybrid controller 82 calculates a target (required) output of the vehicle from the accelerator operation amount Acc as the driver-requested output amount and the vehicle speed V, when the vehicle is travelling at the vehicle speed V, and calculates a necessary total target output from the target output of the vehicle and a charge required value. Then, the hybrid controller 82 obtains necessary input torque Tin of the mechanical stepwise variable transmission 20, according to the speed ratio γ2 of the mechanical gear position of the mechanical stepwise variable transmission 20, so that the total target output is obtained. Further, the hybrid controller 82 calculates a target engine output (required engine output) with which the necessary input torque Tin is obtained, in view of assist torque of the second motor-generator MG2, etc. Then, the hybrid controller 82 controls the engine 14 and controls the amount of power generation (regenerative torque) of the first motor-generator MG1 in a feedback manner, so as to achieve the engine speed Ne and engine torque Te with which the target engine output is obtained. The hybrid controller 82 performs the output control of the engine 14, via an engine controller 58 including an electronic throttle valve that controls the intake air amount, fuel injection device that controls the fuel injection amount, ignition device of which the ignition timing can be controlled to be advanced or retarded, and so forth. Also, the hybrid controller 82 performs power running control and regeneration control of the first motor-generator MG1 and the second motor-generator MG2, while performing charge/discharge control of the power storage device 40 via the inverter 38.
The virtual shift controller 84 controls the electric continuously variable transmission 16 so as to establish a plurality of virtual gear positions having different speed ratios γ0 (=Ne/Nout) of the engine speed Ne to the output rotational speed Nout of the mechanical stepwise variable transmission 20. The virtual shift controller 84 performs shift control according to a predetermined virtual gear position shift map, so as to establish the virtual gear positions. The speed ratio γ0 is a value (γ0=γ1×γ2) obtained by multiplying the speed ratio γ1 of the electric continuously variable transmission 16 by the speed ratio γ2 of the mechanical stepwise variable transmission 20. As shown in
Like the mechanical gear position shift map, the virtual gear position shift map used for switching the virtual gear positions is determined in advance, using the output rotational speed Nout and the accelerator operation amount Acc as parameters.
Here, the virtual stepwise shift control performed by the virtual shift controller 84 and the mechanical stepwise shift control performed by the mechanical shift controller 80 are controlled in coordination. Namely, the number of speeds of the virtual gear positions is 10 speeds, which is larger by four speeds than the number of speeds of the mechanical gear positions, and one virtual gear position or two or more virtual gear positions are assigned to each mechanical gear position, so that the virtual gear position(s) is/are established while the mechanical gear position is established.
With the above arrangement in which the plurality of virtual gear positions are assigned to the plurality of mechanical gear positions, a 1⇄2 shift of the mechanical gear position is performed when a 3⇄4 shift of the virtual gear position is performed, and a 2⇄3 shift of the mechanical gear position is performed when a 6⇄7 shift of the virtual gear position is performed, while a 3⇄4 shift of the mechanical gear position is performed when a 9⇄10 shift of the virtual gear position is performed. In this case, the mechanical gear position shift map is determined such that shifts of the mechanical gear positions are performed in the same timing as shift timing of the virtual gear positions. More specifically, the upshift lines “3→4”, “6→7”, and “9→10” in
The virtual shift controller 84 functionally includes a gear position assignment changing unit 86 in connection with assignment of the gear positions. The gear position assignment changing unit 86 changes assignment of the gear positions when there is a restriction on establishment of a part of the mechanical gear positions. The gear position assignment changing unit 86 performs signal processing according to steps S1-S5 of the flowchart of
In step S2, it is determined whether only the mechanical 4th-speed gear position is inhibited. If only the mechanical 4th-speed gear position is inhibited, step S4 is executed. As one example of the case where only the mechanical 4th-speed gear position is inhibited, a clutch-to-clutch shift to the mechanical 4th-speed gear position having the smallest speed ratio γ2 is inhibited when the oil pressure is low, for example. In step S4, the gear position assignment table of
If a negative decision (NO) is made in the above step S2, namely, any of the mechanical 1st-speed gear position to the mechanical 3rd-speed gear position is inhibited, the virtual gear positions are restricted in step S5. In step S5, the shift range of the virtual gear positions is limited, such that the virtual gear position assigned to the mechanical gear position that is lower by one speed than the inhibited mechanical gear position, in the normal-time gear position assignment table of
When the mechanical 4th-speed gear position is inhibited, too, the virtual 9th-speed gear position as the highest-speed position of those assigned to the mechanical 3rd-speed gear position that is lower by one speed than the mechanical 4th-speed gear position may be set to the upper limit, and shift control may be performed within the range of the virtual 1st-speed gear position to the virtual 9th-speed gear position, as in the case where the mechanical 2nd-speed gear position or the mechanical 3rd-speed gear position is inhibited. Also, when the mechanical 1st-speed gear position is inhibited, namely, when the first clutch C1 cannot be engaged, the virtual stepwise shift control is inhibited, for example, and the hybrid controller 82 performs stepless shift control on the electric continuously variable transmission 16. With regard to the mechanical stepwise variable transmission 20, the mechanical 4th-speed gear position, in which the first clutch C1 need not be engaged, is established. In the meantime, when any of the mechanical 1st-speed gear position to the mechanical 3rd-speed gear position cannot be used, because of a low oil temperature, or for other temporary reasons, all of the virtual gear positions up to the virtual 10th-speed gear position may be assigned to the mechanical gear positions that can be used, as the upper limit, and the electric continuously variable transmission 16 and all of the virtual gear positions may be used for shifting. In this case, control is easy when returning to normal control under which shift control is performed using all of the mechanical gear positions, due to increase of the oil temperature, for example, and shock and the feeling of strangeness given to the driver can be reduced.
Referring back to
Thus, in the vehicular drive system 10 of this embodiment, the electric continuously variable transmission 16 is placed in a selected one of a plurality of virtual gear positions having different speed ratios γ0 of the engine speed Ne to the output rotational speed Nout, and the electric continuously variable transmission 16 is shifted up or down according to the predetermined virtual gear position shift map. Therefore, the engine speed Ne is changed stepwise at the time of shifting, and the same or similar shift feeling as that provided by the mechanical stepwise variable transmission is obtained. In this case, the number (10 in this embodiment) of speeds of the virtual gear positions of the electric continuously variable transmission 16 is equal to or larger than the number (4 in this embodiment) of speeds of the mechanical gear positions of the mechanical stepwise variable transmission 20. The vertical gear positions are assigned to the mechanical gear positions such that one virtual gear position or two or more virtual gear positions is/are established with respect to each mechanical gear position. Further, on a shift to a particular virtual gear position, such as a shift from the virtual 3rd-speed gear position to the virtual 4th-speed gear position, a shift of the mechanical gear position is performed in the same timing as the shift timing of the virtual gear position. Thus, shifting of the mechanical stepwise variable transmission 20 is accompanied by change of the engine speed Ne, and the driver is less likely or unlikely to feel strange or uncomfortable even if shift shock occurs during shifting of the mechanical stepwise variable transmission 20.
Also, when the mechanical 2nd-speed gear position or mechanical 3rd-speed gear position of the mechanical stepwise variable transmission 20 cannot be established due to a failure, or the like, the shift range of the virtual gear positions is limited, such that the highest-speed position of the virtual gear positions assigned to the mechanical gear position that is lower by one speed than the mechanical gear position that cannot be established is set to the upper limit; therefore, the vehicle speed V is restricted with increase of the engine speed Ne. Therefore, the MG2 rotational speed Nm corresponding to the input rotational speed of the mechanical stepwise variable transmission 20 is prevented from excessively increasing.
In the above embodiment, when there is a restriction on establishment of the mechanical gear positions, the gear position assignment table for use in the case where the mechanical 4th-speed position is inhibited is used according to the flowchart of
While some embodiments of the disclosure have been described in detail with reference to the drawings, these are mere examples of implementation, and this disclosure may be embodied with various changes or improvements, based on the knowledge of those skilled in the art.
Number | Date | Country | Kind |
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2016-084068 | Apr 2016 | JP | national |