JP2014108011A - Shift control device of electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shift control device of an electric automobile capable of achieving a target shift stage, and thus, preventing a situation such as travel incapability when gear change cannot be completed by certainly engaging a dog tooth by appropriately executing rotation synchronization of a shift gear utilizing an electric motor.SOLUTION: In preselection of a gear mechanism G2 to a predetermined shift stage, a dog tooth is engaged by operating a synchronization mechanism of a shift stage by a hydraulic cylinder 6 upon executing rotation synchronization control for matching rotational speed of a target shift gear to target rotational speed by transmitting driving force of an electric motor 3 to a speed changer 2. An oil temperature correction coefficient is set to a larger value as oil temperature of the speed changer is lower since rotation of the shift gear suddenly falls after rotation synchronization when the oil temperature is low, and the target rotational speed is set to an increase side based on the oil temperature correction coefficient.

Description

  The present invention relates to a shift control device for an electric vehicle, and more specifically, a shift control device capable of smoothly performing a shift by rotating and synchronizing a shift gear of a transmission using an electric motor mounted as a driving power source in the vehicle. About.

  In order to improve the efficiency of an engine vehicle equipped with an engine as a conventional driving power source, a hybrid electric vehicle equipped with an electric motor as a driving power source in addition to the engine, or an electric vehicle equipped with an electric motor instead of the engine (Hereinafter collectively referred to as an electric vehicle). In such an electric vehicle, the electric motor is operated in a traveling region where the engine operating efficiency is lowered, or the electric motor is operated as a generator when the vehicle is decelerated, etc., and regenerative energy is recovered. Has achieved an improvement.

  In recent years, electric vehicles have been adopted for large vehicles such as trucks and buses, and transmissions have been automated. As an automatic transmission, a torque converter type transmission and a CVT (Continuously Variable Transmission) are generally used, but the capacity may be insufficient for a large vehicle such as a truck or a bus that transmits a large driving force. Therefore, an automatic transmission is used in which a shift operation and a clutch connection / disconnection operation are automatically performed by an actuator based on a conventional manual transmission.

  As is well known, in an always-meshing manual transmission, the driving force from the driving power source is transmitted to each transmission gear on the output shaft via the gear ratio of each gear, and each transmission gear is transmitted on the output shaft. Always idle at a speed according to the gear ratio. Then, each speed change gear is selectively coupled to the output shaft to achieve a shift stage (so-called gear engagement), and power is transmitted to the drive wheel via the output shaft via the corresponding gear ratio. Since the output shaft always rotates in accordance with the vehicle speed, it is necessary to synchronize rotation in advance in order to connect the target transmission gear to the output shaft.

  In view of this, a synchronizing mechanism for rotational synchronization is provided between each transmission gear and the output shaft. The synchronization mechanism sleeve is slid on the output shaft in conjunction with the driver's shift operation, and the speed of the transmission gear is synchronized with the output shaft side using the frictional force generated by the cam. The dog teeth on the sleeve side are meshed with each other. In the automatic transmission, the sliding of the sleeve is performed by an actuator instead of the driver's shift operation.

  As described above, the rotational speed of the transmission gear is synchronized with the output shaft side by the synchronization mechanism for each shift, but it is desirable to reduce the burden on the synchronization mechanism at that time. In an electric vehicle, the rotational speed of the transmission gear on the output shaft can be freely adjusted by inputting the driving force of the electric motor to the transmission. Therefore, at the time of shifting while the vehicle is running, control is performed in advance to make the rotational speed of the transmission gear actively approach and synchronize with the rotational speed on the output shaft side using an electric motor in advance.

For example, the rotational speed of the output shaft of the transmission is calculated based on the vehicle speed or the like, and the rotational speed of the target transmission gear is controlled by the electric motor using the output shaft rotational speed as a target value. If a shift is performed during acceleration / deceleration of the vehicle, the rotation speed of the output shaft changes between the start of the shift and the engagement of the dog teeth. In some cases, the target value is corrected based on the differential value of the vehicle speed (hereinafter referred to as the conventional technique).
Then, when the rotation speed of the transmission gear reaches the vicinity of the target value and the rotation synchronization is completed, the sleeve is slid by the actuator. The final slight rotational difference is synchronized by the synchro mechanism, and both dog teeth mesh with each other to complete the shift.

By the way, the internal mechanism of the automatic transmission is lubricated with oil, and when the oil temperature changes, the oil viscosity also changes and the rotational resistance acting on the internal mechanism increases and decreases, which also affects the rotation synchronization of the transmission gear by the above-mentioned electric motor. Effect. Therefore, for example, a technique disclosed in Patent Document 1 has been proposed as a countermeasure considering this point.
In the technique disclosed in Patent Document 1, the torque applied to the transmission gear by the electric motor at the time of rotation synchronization is corrected according to the oil temperature of the transmission, so that the transmission gear always has a substantially constant time regardless of the oil temperature change. The rotational speed has reached the target value. This eliminates the difference between the time required to complete the rotation synchronization and the time required to complete the shift, thereby improving the shift feeling.

JP 2000-295709 A

As described above, the rotational resistance acting on the internal mechanism increases and decreases according to the oil temperature change of the automatic transmission. Especially at low oil temperature when the oil viscosity increases, the transmission gear receives a large rotational resistance and is gearing (rotating During the period from the completion of the synchronization to the engagement of the dog teeth), the rotation rapidly decreases. On the other hand, since the output shaft side changes in accordance with the vehicle speed, dog teeth are engaged by the synchro mechanism in a state where a large rotational difference is generated between the two.
That is, although the rotation is synchronized by the electric motor, a situation occurs in which the rotation synchronization is not effectively utilized for the engagement of the dog teeth. In a situation where the rotational speed of the transmission gear is far from the output shaft side due to such a decrease in rotation during gear engagement, a large force is required for the operation of the sleeve, and the driving force of the actuator is insufficient and the dog teeth cannot be engaged. .

  According to the technique of Patent Document 1, although the time required for rotation synchronization can be made uniform regardless of changes in the oil temperature, the phenomenon that the transmission gear decreases after rotation synchronization cannot be dealt with at all and cannot be a solution. . In addition, there is a conventional technique that corrects the target value of rotation synchronization based on the differential value of the vehicle speed as described above, but this method is a countermeasure when the output shaft side changes in rotation with the acceleration / deceleration of the vehicle. It is not a measure focusing on the rotation change of the side. Therefore, this prior art cannot cope with the reduction in the rotation speed of the transmission gear that occurs when the oil temperature is low, and it cannot be a solution.

As a result, the target shift speed cannot be achieved due to the inability to engage the dog teeth, so that an error determination indicating that the shift is impossible is made after a predetermined time has elapsed. As a countermeasure in this case, forcible power transmission cutoff control, for example, switching to the neutral of the transmission or clutch cutoff is executed for safety, but the vehicle falls into an inoperable state. Further, as another countermeasure, there is a case where a shift to another alternative shift stage is attempted, but the traveling performance of the vehicle is significantly deteriorated and the original traveling cannot be continued.
The present invention has been made to solve such problems, and the object of the present invention is to properly engage the dog teeth by appropriately carrying out the rotation synchronization of the transmission gear using an electric motor. It is an object of the present invention to provide a shift control device for an electric vehicle that can achieve a target shift stage and prevent a situation such as inability to travel when the shift cannot be completed.

  To achieve the above object, according to a first aspect of the present invention, there is provided an electric vehicle capable of traveling by transmitting a driving force of an electric motor to a driving wheel side via a transmission, and when the operation of switching the gear position of the transmission is performed. Rotational synchronization for controlling the rotational speed of the transmission gear to be switched to coincide with the first target rotational speed set based on the rotational speed on the output shaft side of the transmission. The lower the oil temperature detected by the control means, the oil temperature detecting means for detecting the oil temperature of the transmission, and the lower the oil temperature detected by the oil temperature detecting means, the higher the first target rotational speed to the higher side than the rotational speed on the output shaft side. And target rotation speed setting means for setting.

  In a situation where the oil temperature of the transmission is low, the rotation speed of the transmission gear rapidly decreases after the rotation synchronization, but the first target rotation speed is set to increase according to the oil temperature. Thus, the rotational speed of the transmission gear is increased in advance. Therefore, even if the transmission gear subsequently decreases in rotation, it can be reliably maintained in the vicinity of the rotation speed on the output shaft side when the dog teeth are engaged. As a result, the burden on the synchro mechanism when meshing the dog teeth can be reduced, the dog gears can be meshed quickly and reliably to achieve the target gear position, and the situation such as the inability to run when the gear shift cannot be completed will occur. Can be prevented.

According to a second aspect of the present invention, the electric vehicle further includes vehicle speed detection means for detecting a vehicle speed of the electric vehicle, and the higher the vehicle speed detected by the vehicle speed detection means, the higher the vehicle speed detected by the vehicle speed detection means. Is set on the increase side with respect to the rotation speed on the output shaft side.
When the vehicle speed is high, the speed reduction of the transmission gear after the rotation synchronization becomes abrupt. Therefore, by setting the first target rotational speed to the increasing side as the vehicle speed increases, the rotational speed of the transmission gear can be more reliably maintained near the rotational speed on the output shaft side at the time of engagement of the dog teeth.

According to a third aspect of the present invention, the electric vehicle further includes an accelerator opening degree detecting unit that detects an accelerator opening degree, and the target rotational speed setting unit increases the accelerator opening degree detected by the accelerator opening degree detecting unit. The target rotational speed of 1 is set on the increase side with respect to the rotational speed on the output shaft side.
When the accelerator opening is large, the rotation speed on the output shaft side is expected to increase soon. Therefore, by setting the first target rotational speed to the increasing side as the accelerator opening is larger, the rotational speed of the transmission gear can be more reliably maintained near the rotational speed on the output shaft side at the time of engagement of the dog teeth. it can.

According to a fourth aspect of the present invention, in the electric vehicle, the target rotational speed setting means further increases the first target rotational speed from the rotational speed on the output shaft side as the transmission gear stage is on the lower gear stage side. Is set to
The lower the gear position, the more rapidly the output shaft side rotates. Therefore, by setting the first target rotational speed to the increasing side as the gear is closer to the lower gear stage side, the rotational speed of the transmission gear is more reliably maintained near the rotational speed on the output shaft side when the dog teeth are meshed. Can do.

According to a fifth aspect of the present invention, in the electric vehicle, after the completion of the rotation synchronization by the rotation synchronization control means, with the electric motor as a center on the zero torque that can maintain the rotation speed of the transmission gear, the transmission gear is positively and negatively connected to the transmission gear. Torque fluctuation control means for executing torque fluctuation control for alternately applying the minute torque of.
Not only is the rotation speed of the transmission gear kept near the rotation speed on the output shaft side at the time of meshing the dog teeth, but the phase of the transmission gear with respect to the output shaft side constantly changes due to the addition of minute torque, so that the speed is further increased. Shifting can be completed by reliably engaging the dog teeth.

  According to a sixth aspect of the present invention, in the electric vehicle, the second target in which the rotational speed of the transmission gear is set corresponding to the rotational speed on the output shaft side during execution of torque fluctuation control by the torque fluctuation control means. Torque correction means for correcting the positive and negative minute torques added by the torque fluctuation control means so as to be held in the vicinity of the rotation speed is provided, and the torque correction means has a second target rotation speed of the transmission gear. When the rotational speed falls below the zero torque, the positive minute torque is corrected to be larger than the negative minute torque, and the second gear rotation speed is set in advance as the rotational speed of the transmission gear. When the hysteresis set value is exceeded, correction is performed so that the negative minute torque becomes larger than the positive minute torque with reference to zero torque.

  Accordingly, the rotational speed of the transmission gear during gear engagement is maintained in the vicinity of the target rotational speed by correcting the minute torque on the positive side and the negative side, for example, correcting the variation amount of the minute torque and correcting the variation time. Therefore, since the speed change gear constantly changes its phase in a state of being rotationally synchronized with the output shaft side, it is possible to complete the speed change by meshing the dog teeth more quickly and reliably. Further, when the rotational speed of the transmission gear increases, the correction of the minute torque is delayed based on the hysteresis setting value. Even when the rotational speed of the transmission gear exceeds the target rotational speed at a low oil temperature where the rotational resistance is large, there is a possibility that the rotational resistance falls below the target rotational speed immediately after that. In such a case, unnecessary correction of minute torque is prevented, and minute torque is corrected only when it is necessary to reduce the rotation speed of the transmission gear. It can be kept well near the target rotational speed.

According to a seventh aspect of the present invention, in the above electric vehicle, the torque fluctuation control means further continues zero torque for a preset duration between the positive and negative minute torques.
If the phase of the speed change gear with respect to the output shaft is constantly changed, there is a possibility that the phase in which the dog teeth can mesh is instantaneously passed and cannot be meshed. By providing a period during which the torque is maintained at zero torque, the phase change is interrupted during the period. As a result, an opportunity for meshing the dog teeth can be created, and the dog teeth can be meshed more reliably.

1 is an overall configuration diagram showing a hybrid truck to which a shift control device of an embodiment is applied. It is a flowchart which shows the preselect control routine which vehicle ECU of 1st Embodiment performs. It is a figure which shows the map for calculating an oil temperature correction coefficient based on the oil temperature of a transmission. It is a figure which shows the map for calculating a speed correction coefficient based on a vehicle speed. It is a figure which shows the map for calculating an accelerator correction coefficient based on an accelerator opening. It is a figure which shows the map for calculating a gear correction coefficient based on a gear stage. It is a flowchart which shows the preselect control routine which vehicle ECU of 2nd Embodiment performs. It is explanatory drawing which shows the execution range of the torque fluctuation control with respect to an operation stroke. It is a flowchart which shows the torque fluctuation control routine which vehicle ECU of 2nd Embodiment performs. It is a time chart which shows the execution situation of torque fluctuation control. It is a time chart which shows the rotation fluctuation state of the transmission gear in gear setting.

[First Embodiment]
A first embodiment in which the present invention is embodied in a shift control device for a hybrid truck will be described below.
FIG. 1 is an overall configuration diagram showing a hybrid truck to which a shift control apparatus according to this embodiment is applied. In the following description, the truck is referred to as a vehicle. A vehicle is equipped with a diesel engine (hereinafter referred to as an engine) 1 as a driving power source. An output shaft 1a of the engine 1 projects rearward (to the right in the drawing) of the vehicle and is connected to an input shaft 2a of an automatic transmission (hereinafter simply referred to as a transmission) 2. The transmission 2 has six forward speeds (first speed to sixth speed) and one reverse speed. After the power of the engine 1 is input to the transmission 2 via the input shaft 2a, the transmission 2 according to the gear speed. The speed is changed and transmitted from the output shaft 2 b to the left and right drive wheels 14 via the differential 12 and the drive shaft 13.

The transmission 2 is configured as a so-called dual clutch transmission, and includes an electric motor 3 as a driving power source. The details of the dual clutch transmission are described in, for example, Japanese Patent Application Laid-Open No. 2009-035168, and therefore only a brief description is given in the present embodiment. For this reason, FIG. 1 shows the transmission 2 in a schematic representation different from the actual mechanism, and the configuration and operating state of the transmission 2 will also be conceptually described in the following description.
As is well known, a dual clutch type transmission is provided with an odd-numbered gear stage and an even-numbered gear stage as mutually independent power transmission systems, and when one of them is transmitting power, the other is predicted next. This is a system that completes switching to the next gear without interrupting power transmission by switching to gears in advance.

  That is, as shown in FIG. 1, the input shaft 2a of the transmission 2 is connected to a gear mechanism G1 consisting of odd gears (first, third, and fifth gears) via a clutch C1, and the input shaft 2a. A gear mechanism G2 composed of an even-numbered gear stage (2, 4, 6th gear stage) is connected to the motor via the clutch C2 and the electric motor 3. The output sides of these gear mechanisms G1 and G2 are connected to the common output shaft 2b.

A hydraulic cylinder 6 is connected to each of the clutches C1 and C2, and both hydraulic cylinders 6 are connected to a hydraulic pressure supply source 9 through an oil passage 8 in which an electromagnetic valve 7 is interposed. When the solenoid valve 7 is opened, hydraulic oil is supplied from the hydraulic supply source 9 to the hydraulic cylinder 6 through the oil passage 8, and the hydraulic cylinder 6 is operated to switch the corresponding clutch C1, C2 from the disconnected state to the connected state. .
On the other hand, when the solenoid valve 7 is closed, the hydraulic cylinder 6 is not operated due to the supply of hydraulic oil being stopped, and the clutches C1 and C2 are switched from the connected state to the disconnected state by a pressure spring (not shown). Note that the drive system of the clutches C1 and C2 is not limited to this. For example, air drive or motor drive may be employed instead of the hydraulic drive.

  The gear mechanisms G1 and G2 of the transmission 2 are each provided with a gear shift unit 10. Although not shown, the gear shift unit 10 incorporates a plurality of hydraulic cylinders that operate shift forks corresponding to the respective shift speeds in the gear mechanisms G1 and G2, and a plurality of electromagnetic valves that operate each hydraulic cylinder. The gear shift unit 10 is connected to the above-described hydraulic supply source 9 via an oil passage 11, and the hydraulic oil supplied from the hydraulic supply source 9 is switched by each electromagnetic valve, and the corresponding hydraulic cylinder passes through the shift fork. The sleeve is slid to change the gear positions of the gear mechanisms G1 and G2.

  At the time of shifting, the clutch C1, C2 is basically always switched in the reverse direction. For this reason, when one of the gear mechanisms G1 and G2 has achieved the shift speed by connecting one of the clutches C1 and C2, and the power is being transmitted, the other clutch C1 and C2 is disconnected and the corresponding gear mechanism is disengaged. In G1 and G2, none of the gears transmit power. Therefore, in the other gear mechanisms G1 and G2, it is possible to advance to the next gear stage (the gear stage on the high gear side or the low gear side adjacent to the current gear stage) in advance (this operation is performed in advance). Called select). When the shift timing is reached after preselection, the transmission / reception state of the clutches C1 and C2 is reversed, so that power transmission is started at the shift stage achieved by preselection with the other gear mechanisms G1 and G2, and the power transmission is interrupted. The shift is complete without

Although not shown, the electric motor 3 is composed of a rotor and a stator that are arranged in an inner and outer double, and a rotating shaft that rotatably supports the rotor is connected to the output side of the clutch C2 and the input side of the gear mechanism G2. . A battery 5 for traveling is electrically connected to the electric motor 3 via an inverter 4, and power running control and regenerative control of the electric motor 3 are performed by the inverter 4.
In the power running control of the electric motor 3, the DC power stored in the traveling battery 5 is converted into AC power by the inverter 4 and supplied to the electric motor 3, and the electric motor 3 operates as a motor to input the driving force to the gear mechanism G2. In the regenerative control of the electric motor 3 performed at the time of deceleration of the vehicle, the electric motor 3 generates a regenerative braking force by reverse driving from the drive wheel 14 side, and the generated AC power is converted into DC power by the inverter 4. And the battery 5 for traveling is charged.

  The vehicle includes an input / output device (not shown), a storage device (ROM, RAM, etc.) used to store control programs and control maps, a central processing unit (CPU), a vehicle ECU (control unit) equipped with a timer counter, etc. 16 is installed. The vehicle ECU 16 performs integrated control of the entire vehicle based on information from the engine ECU 17, the inverter ECU 18, and the travel battery ECU 19, or information from sensors described below. Based on the command from the vehicle ECU 16, the engine ECU 17 controls the engine 1, the inverter ECU 18 controls the electric motor 3, and the battery ECU 19 manages the running battery 5.

  On the input side of the vehicle ECU 16, there are an input rotational speed sensor 23 for detecting the input rotational speed Nin1 of the gear mechanism G1, an input rotational speed sensor 24 for detecting the input rotational speed Nin2 of the gear mechanism G2 (= the rotational speed of the electric motor 3), A gear position sensor 25 that detects the gear position of the gear mechanisms G1 and G2, an output rotation speed sensor 28 that detects the output rotation speed Nout of the transmission 2 (the rotation speed of the output shaft 2b of the gear mechanisms G1 and G2) (vehicle speed detection means) ), A lever position sensor 30 for detecting the position of the select lever 29, a brake hydraulic pressure sensor 35 for detecting a brake hydraulic pressure Pb generated in response to a depression force on the brake pedal 34, and an oil for detecting an oil temperature Toil of the transmission 2. Sensors such as a temperature sensor 36 (oil temperature detecting means) are connected. Devices such as the electromagnetic valves 7 of the clutches C1 and C2 and the electromagnetic valves of the gear shift unit 10 are connected to the output side of the vehicle ECU 16.

For example, the vehicle ECU 16 calculates a required torque necessary for traveling of the vehicle 1 from the accelerator opening θacc input through the engine ECU 17, and converts this required torque into a torque generated by the engine 1 and a torque generated by the electric motor 3. To distribute. At the same time, the vehicle running mode (engine running, motor running, engine / motor running) is set based on the required torque, the running state of the vehicle, the operating state of the engine 1 and the electric motor 3, the SOC of the running battery 5, and the like. select. Then, a command is output to the engine ECU 17 and the inverter ECU 18 to execute the selected travel mode, and the shift control of the transmission 2 is appropriately executed.
The engine ECU 17 controls and operates the engine 1 so as to achieve the travel mode and engine torque set by the vehicle ECU 16. An engine rotational speed sensor 22 for detecting the rotational speed Ne of the engine 1 and an accelerator sensor 27 (accelerator opening detecting means) for detecting the opening θacc of the accelerator pedal 26 are connected to the input side of the engine ECU 17.

In addition, the inverter ECU 18 drives and controls the inverter 4 to operate the electric motor 3 so as to achieve the travel mode and the torque of the electric motor 3 set by the vehicle ECU 16.
The battery ECU 19 detects the temperature of the traveling battery 5, the voltage of the traveling battery 5, the current flowing between the inverter 4 and the traveling battery 5, and the SOC of the traveling battery 5 from these detection results. The SOC is output to the vehicle ECU 16 together with the detection result.

By the way, since the electric motor 3 is connected to the gear mechanism G2 on the even gear stage side of the transmission 2, the motor 3 is used to synchronize the rotational speed N of each transmission gear to the output shaft 2b side during preselection. It is possible to reduce the burden on the synchro mechanism. Therefore, the rotation synchronization control by the electric motor 3 is executed at the time of preselecting the gear mechanism G2 while the vehicle is running.
However, even if rotation synchronization is achieved by such control, as described in [Problem to be Solved by the Invention], particularly in a situation where the oil temperature Toil of the transmission 2 is low, the rotation synchronization is completed. A situation occurs in which the dog teeth cannot be meshed due to a rapid rotation reduction of the transmission gear.

Therefore, the present inventor expects a reduction in the rotation of the transmission gear during gear engagement in order to eliminate the problem, and sets the target rotation speed Ntgt when rotating the transmission gear to be higher than the rotation speed Nout on the output shaft 2b side. We found a measure to set on the rotation side. Hereinafter, the process which vehicle ECU16 performs for the said countermeasure is demonstrated.
Here, based on the above viewpoint, in the present embodiment, a value on the higher rotation side than the output rotation speed Nout is applied as the target rotation speed Ntgt (first target rotation speed) for rotation synchronization by the electric motor 3. Apart from this, a target rotational speed Ntgt (second target rotational speed) that matches the output rotational speed Nout is also applied during torque fluctuation control executed in the second embodiment to be described later.

Therefore, in the following explanation, UP is added to the target rotational speed Ntgt higher than the output rotational speed Nout for rotational synchronization (NtgtUP> Nout), and the target coincides with the output shaft rotational compatibility Nout described in the second embodiment. A distinction is made between the rotational speed Ntgt (= Nout).
In actual control, a value obtained by multiplying the output shaft rotation speed Nout by the gear ratio (Nout / gear ratio) is set as the target rotation speed Ntgt, and the control is performed so that the input rotation speed Nin2 matches the target rotation speed Ntgt. However, in the following description, for the sake of convenience, it is assumed that the target rotational speed Ntgt matches the output rotational speed Nout as described above.

FIG. 2 is a flowchart showing a preselect control routine executed by the vehicle ECU 16. The vehicle ECU 16 executes this routine at a predetermined control interval when the ignition switch of the vehicle is turned on.
First, in step S2, it is determined whether or not the preselect timing of the gear mechanism G2 has been reached. If No (No), the routine is once terminated. When the determination in step S2 is Yes (positive), the process proceeds to step S4, and the target rotational speed NtgtUP setting process is executed. That is, the output rotation speed Nout detected by the output rotation speed sensor 28 is set as the base value Nbase, and the target rotation speed NtgtUP is calculated according to the following equation (1) (target rotation speed setting means).

NtgtUP = Nbase × KNtemp × KNv × KNacc × KNgear ...... (1)
Here, KNtemp is an oil temperature correction coefficient, KNv is a speed correction coefficient, KNacc is an accelerator correction coefficient, and KNgear is a gear correction coefficient, which are calculated based on preset maps shown in FIGS.

FIG. 3 shows a map for calculating the oil temperature correction coefficient KNtemp based on the oil temperature Toil of the transmission 2, and the oil temperature correction coefficient KNtemp is calculated as a larger value as the oil temperature Toil is lower.
FIG. 4 shows a map for calculating the speed correction coefficient KNv based on the vehicle speed V. The speed correction coefficient KNv is calculated as a larger value as the vehicle speed V is higher.
FIG. 5 shows a map for calculating the accelerator correction coefficient KNacc based on the accelerator opening θacc. The accelerator correction coefficient KNacc is calculated as a larger value as the accelerator opening θacc is larger.
FIG. 6 shows a map for calculating the gear correction coefficient KNgear based on the gear stage of the transmission 2 (the gear stage currently transmitting power), and the gear correction coefficient KNgear is calculated as a larger value as the gear speed is lower.

  The target rotation speed NtgtUP is always calculated as a value on the higher rotation side than the output rotation speed Nout by an amount corresponding to the rotation reduction of the transmission gear during gear engagement according to the equation (1). In other words, the gear shifts during rotation after the gear synchronization based on the target rotation speed NtgtUP, but the time when the dog teeth mesh with the gear engagement (more specifically, the frictional force generated by the cam action of the synchro mechanism). Thus, the target rotational speed NtgtUP is calculated so that the rotational speed N of the transmission gear is maintained in the vicinity of the output rotational speed Nout at the time when rotational synchronization between the transmission gear and the output shaft 2b is started.

  When the target rotational speed NtgtUP is calculated as described above, the vehicle ECU 16 proceeds to step S6. In step S6, the rotational speed N of the transmission gear is calculated based on the input rotational speed Nin2 of the gear mechanism G2 detected by the input rotational speed sensor 24 and the gear ratio of the target gear to be preselected, and then the rotational speed N Is controlled to match the target rotational speed NtgtUP (rotation synchronization control means).

Thereafter, in step S8, it is determined whether or not the rotation synchronization between the transmission gear and the output shaft 2b is completed. If No, the process of step S6 is repeated. When the determination in step S8 is Yes, the process proceeds to step S10, and the gear shift unit 10 of the gear mechanism G2 is driven and controlled to start gear-shifting to be preselected. When gearing is started, the sleeve of the synchro mechanism slides on the output shaft 2b and generates a frictional force by the cam. Using this frictional force, the transmission gear and the output shaft 2b side are synchronized in rotation. When the dog teeth mesh, the gear setting is completed.
Further, in step S12, it is determined whether or not a preset gear engagement try time T1 has elapsed since the start of gear engagement. In subsequent step S14, it is determined whether or not gear engagement has been completed based on detection of the gear position sensor 25. judge. At the beginning of gearing, since the gearing try time T1 has not yet elapsed and gearing has not been completed, the determination of No is made in both steps S12 and S14 and the process returns to step S10.

In this manner, the process of steps S10 to S14 is repeated to continue the gear engagement. When the gear engagement is completed before the gear engagement try time T1 elapses, the process shifts from step S14 to step S16 to make a gear engagement completion determination. The routine ends later.
Accordingly, when preselection is normally completed by the first gear setting as described above, the determination of No is made in step S2 of FIG. 2 and the gear setting is not repeated. Then, the connection / disconnection state of the clutches C1 and C2 is reversed at the subsequent shift timing, whereby the shift to the target shift stage of the gear mechanism G2 is completed.

  On the other hand, when the gear engagement try time T1 elapses before the gear engagement is completed, the vehicle ECU 16 proceeds from step S12 to step S18 and makes a gear engagement failure determination. In this case, since gearing cannot be performed and completed, an operation to try gearing again (this operation is called a retry operation) is required. In order to perform the retry operation, it is necessary to return the synchro mechanism operated halfway in the gear engagement direction by the process of step S10. Therefore, in the subsequent step S20, a stroke return operation for driving and controlling the gear shift unit 10 in the reverse direction is executed to return the stroke of the synchro mechanism.

As a result, the gear mechanism G2 is returned to the state before the gear engagement. Therefore, when the routine of FIG. 2 is subsequently executed, the vehicle ECU 16 determines Yes in step S2 because pre-selection has not been completed yet, and after step S4, performs the same gear as described above as a retry operation. try again.
As described above, when the gear mechanism G2 is preselected, first, the gear of the target gear stage is rotationally synchronized to the output shaft 2b side by the electric motor 3 by the processing in steps S4 to S8, and then in steps S10 to S14. Gearing is performed by processing.
Then, the target rotational speed NtgtUP when the transmission gear is rotationally synchronized is increased from the base value Nbase (= output rotational speed Nout) as the oil temperature Toil of the transmission 2 is lower based on the above equation (1).

If the target rotational speed NtgtUP is set as the output rotational speed Nout and the oil temperature Toil is low, the rotational speed N of the transmission gear can be significantly lower than the rotational speed Nout on the output shaft 2b side and the dog teeth can be meshed after the rotational synchronization. Disappear. And the rotation reduction of the transmission gear at this time becomes so rapid that the oil temperature Toil is low.
Therefore, by increasing the target rotation speed NtgtUP according to the oil temperature Toil, the rotation speed N of the transmission gear at the time when the rotation synchronization is completed is increased in advance from the output rotation speed Nout. For this reason, even if the transmission gear decreases during the subsequent gear engagement, it can be reliably maintained in the vicinity of the rotational speed Nout on the output shaft 2b side when the dog teeth are engaged.

  In this situation, engagement of the dog teeth is attempted, so that the burden on the synchro mechanism is reduced. The hydraulic cylinder of the gear shift unit 10 can operate the sleeve without requiring a large force, and the dog teeth can be engaged with each other quickly and reliably. A stage pre-select can be achieved. If preselection on the gear mechanism G2 side is impossible, the power transmission on the gear mechanism G1 side must be continued, and the running performance of the vehicle will be greatly reduced. However, by completing the preselection quickly and reliably, Such an unexpected situation can be prevented in advance.

Moreover, in this embodiment, the target rotational speed NtgtUP is set not only according to the oil temperature Toil but also according to the vehicle speed V, the accelerator opening θacc, and the gear position.
When the vehicle speed V is high, the speed change gear is rotationally synchronized in the high rotational speed range, so that the rotational decrease after the rotational synchronization becomes abrupt. Therefore, by increasing the target rotational speed NtgtUP as the vehicle speed V is higher based on the above equation (1), the rotational speed N of the transmission gear can be output more reliably at the time of engagement of the dog teeth even during high-speed traveling. It can be held near the rotational speed Nout on the shaft 2b side.

Further, when the accelerator opening degree θacc is large, it is expected that the rotational speed Nout on the output shaft 2b side will soon increase. Therefore, by increasing the target rotational speed NtgtUP as the accelerator opening degree θacc is larger based on the above formula (1), even when the output shaft 2b side is rotated up after the rotation synchronization, it is more effective at the time of engagement of the dog teeth. The rotational speed N of the transmission gear can be reliably maintained near the rotational speed Nout on the output shaft 2b side.
In the conventional technology based on the differential value of the vehicle speed V, the rotational change on the output shaft 2b side is taken into account. However, because of the correction processing based on the vehicle speed V at that time, the change in the vehicle speed after the rotation synchronization is completed is supported. Can not. Since the change in the vehicle speed V occurs with a predetermined delay with respect to the change in the accelerator opening θacc, if the target rotation speed NtgtUP is set according to the accelerator opening θacc, the change in the rotation on the output shaft 2b side is accelerated. This can be reflected in the target rotational speed NtgtUP, thereby achieving the above-described effects. This setting process is particularly useful for a truck having a heavy vehicle weight because it takes time until the accelerator operation is reflected in the acceleration / deceleration of the vehicle.

Further, the rotation change on the output shaft 2b side after the rotation synchronization affects not only the accelerator opening degree θacc but also the gear stage of the transmission 2, and the output shaft 2b side rapidly rotates and rises as the gear stage is on the lower gear side. . Therefore, by increasing the target rotational speed NtgtUP as the gear position is lower based on the above equation (1), the rotational speed N of the transmission gear can be more reliably set at the time of engagement of the dog teeth regardless of the gear position. Side rotation speed Nout can be maintained.
Therefore, the gear speed preselection can be achieved by meshing the dog teeth more quickly and surely by the setting processing of the target vehicle speed NtgtUP according to the vehicle speed V, the accelerator opening degree θacc, and the gear position.

  By the way, by setting the target rotational speed NtgtUP on the high rotational side, the rotational speeds of the transmission gear and the output shaft 2b are close to each other so that the dog teeth can be easily meshed. If the tips of the dog teeth hit each other, there is a possibility that the dog teeth may be unable to mesh. Therefore, it is conceivable to take a measure assuming such a situation, which will be described below as a second embodiment.

[Second Embodiment]
The overall configuration of the present embodiment is the same as that described with reference to FIG. 1, and the difference is in the processing executed by the vehicle ECU 16. Therefore, parts having the same configuration are denoted by the same member numbers and description thereof is omitted, and the processing of the vehicle ECU 16 will be described mainly.
Here, in the present embodiment, when the sync mechanism of the target gear stage is operated by the hydraulic cylinder for preselection, positive and negative minute torques are applied to the transmission gear to facilitate meshing of the dog teeth. These are added alternately (hereinafter, the control at this time is referred to as torque fluctuation control). Since this torque fluctuation control is executed in a predetermined range during the stroke of the synchro mechanism from the neutral state to the meshing of the dog teeth, the gear position sensor 25 also functions as a stroke sensor in order to specify the stroke range. Is configured to do.

FIG. 7 is a flowchart showing a preselect control routine executed by the vehicle ECU 16. In the flowchart, the same step S numbers are assigned to the same processing as in FIG.
First, when the preselect timing of the gear mechanism G2 is reached in step S2, a setting process of the target rotational speed NtgtUP is executed in accordance with the equation (1) in step S4. In the present embodiment, the target rotational speed NtgtUP is set so that the rotational speed N of the transmission gear coincides with the output shaft 2b side when the torque fluctuation control preceding the meshing of the dog teeth is started.

As shown in FIG. 8, for example, as a range of torque fluctuation control, a stroke range from the time when the neutral range is exceeded to the time when the gear engagement is completed is set. Specifically, the time point when the gearing is completed may be the time point when the dog teeth are completely meshed and the gearing is actually completed (coincides with the time point of the gearing completion stroke described later) or precedes it. It may be when the cam operation for rotation synchronization is completed and the prospect of completion of gearing is established.
Thereafter, the vehicle ECU 16 controls the electric motor 3 based on the target rotational speed NtgtUP in step S6, and when rotation synchronization is completed in the subsequent step S8, gearing is started in step S10. In subsequent step S102, it is determined whether or not the operation stroke of the synchro mechanism is within the range of the torque fluctuation control.

  Since it is not yet within the range of the torque fluctuation control at the beginning of gear engagement, No is determined in step S102, and the process proceeds to step S12. In step S12, it is determined whether or not the gear engagement try time T1 has elapsed. In subsequent step S14, it is determined whether or not an operation stroke for completing gear engagement has been reached. If both determinations are No, the process returns to step S10, and the processes after step S10 are repeated. When the operation stroke falls within the range of torque fluctuation control, a Yes determination is made in step S102, and torque fluctuation control is executed in step S104 (torque fluctuation control means).

  When the gearing completion operation stroke is reached before the gearing try time T1 elapses, the routine proceeds from step S14 to step S16 to determine completion of gearing and the routine is terminated. If the gear engagement try time T1 elapses before the gear engagement completion operation stroke is reached, a gear engagement failure determination is made in step S18, and a stroke return operation is executed in the subsequent step S20.

On the other hand, when the vehicle ECU 16 proceeds to step S104, the vehicle ECU 16 executes a torque fluctuation control routine shown in FIG.
In the torque fluctuation control, as shown in the time chart of FIG. 10, positive and negative minute torques are alternately added to the transmission gear by the electric motor 3. Specifically, the main torque having a large amplitude and time and the sub-torque having a small amplitude and time are opposite to each other around zero torque (indicated by 0 in the figure) that can maintain the rotational speed N of the transmission gear at that time. By repeating the above, periodic torque fluctuations are realized.

The following control amounts are set for such torque fluctuation control.
1) Variation amount of main torque MTmain with respect to zero torque
2) Sub torque fluctuation amount MTsub (<MTmain) with respect to zero torque
3) Main torque fluctuation time Tmain
4) Sub torque fluctuation time Tsub (<Tmain)
5) Zero torque duration Tzero
6) Number of iterations N with main torque and sub torque set as one set

  Each control amount (MTmain, MTsub, Tmain, Tsub, Tzero, N) is set in advance. First, the main torque is added based on the variation amount MTmain and the variation time Tmain, and then the subtorque is based on the variation amount MTsub and the variation time Tsub. Is added. After one set of these main torque and sub torque is repeated N times, the torque is held at zero torque for the duration Tzero. When the zero torque is completed, a series of torque addition procedures from the addition of the main torque to the zero torque are repeated.

  The torque fluctuation control always starts from the main torque, but it is not determined whether the main torque is set to the positive side or the negative side, and as described below, the target rotational speed Ntgt and the rotational speed N of the transmission gear are determined. The positive / negative is determined based on the deviation ΔN (= Ntgt−N). The target rotation speed Ntgt at this time is a value (= Nout) that matches the output rotation speed Nout.

When the routine of FIG. 9 is started, first, the vehicle ECU 16 determines whether or not the deviation ΔN between the target rotational speed Ntgt and the actual rotational speed N of the transmission gear is reversed from negative to positive in step S202. When the determination is No, the routine proceeds to step S204, where it is determined whether or not the deviation ΔN is below a preset hysteresis setting value −ΔN0. When the determination is No, the routine proceeds to step S206, and the routine is terminated after continuing the current torque fluctuation control.
When the deviation ΔN is reversed from negative to positive and the determination in step S202 becomes Yes, the process proceeds to step S208, and the fluctuation amount MTmain is set to the positive side, thereby starting the torque fluctuation control from the positive main torque. (Torque correction means). Further, when the deviation ΔN falls below the hysteresis set value −ΔN0 and the determination in step S204 becomes Yes, the process proceeds to step S210, and the torque fluctuation control is started from the negative main torque by setting the fluctuation amount MTmain to the negative side. (Torque correction means).

Next, the execution state of the preselection of the gear mechanism G2 by the processing of the vehicle ECU 16 will be described with reference to FIGS.
FIG. 11 is a time chart showing the rotational fluctuation state of the transmission gear during gear engagement.
By the process of step S6 in FIG. 7, the rotational speed N of the transmission gear is increased by driving the electric motor 3, and the gear engagement is started after reaching the target rotational speed NtgtUP at the point e in FIG. .

  When the drive of the electric motor 3 is stopped, the rotational speed N of the transmission gear starts to decrease, and when the operation stroke of the synchro mechanism enters the range of torque fluctuation control, torque fluctuation control is started in step S104. At this time, the rotational speed N of the transmission gear decreases to the output rotational speed Nout (= Ntgt) indicated by point a in FIG. 11, and the deviation ΔN (= Ntgt−N) is reversed from the negative side to the positive side. Therefore, based on the processing in step S208 in FIG. 9, the torque fluctuation control is started from the main torque on the positive side after the point a.

  Therefore, as shown in FIG. 10, first, the positive main torque, which is corrected to increase by the fluctuation amount MTmain with respect to the zero torque, is added to the transmission gear over the fluctuation time Tmain. When the fluctuation time Tmain elapses, the torque is switched to the sub-torque, and the negative side sub-torque corrected to decrease by the fluctuation amount MTsub with respect to the zero torque is added to the transmission gear over the fluctuation time Tsub. These main torque and sub torque are repeated N times, after which the additional torque to the transmission gear is maintained at zero torque for the duration Tzero.

  The main gear that controls the torque on the positive side rotates the transmission gear, and the sub-torque that controls the torque on the negative side rotates the transmission gear. Since the main torque fluctuation amount MTmain is larger than the sub-torque fluctuation amount MTsub, and the main torque fluctuation time Tmain is also longer than the sub-torque fluctuation time Tsub, the influence on the rotational speed N of the transmission gear is The main torque is larger than the sub torque. Therefore, after the point a, the rotational speed N of the transmission gear gradually increases, and after the deviation ΔN is reversed from the positive side to the negative side, it falls below the hysteresis set value −ΔN0 at the point b in FIG.

  Here, FIG. 11 shows a schematic rotation fluctuation state of the transmission gear, but as illustrated by the point a, the actual rotation speed N of the transmission gear depends on the torque addition by the torque fluctuation control. It fluctuates minutely with different cycles. For this reason, the speed change gear during torque fluctuation control repeatedly increases and decreases speed to change the phase with respect to the output shaft 2b side.

  Then, after point b in FIGS. 10 and 11, torque fluctuation control is started again from the negative main torque, and the rotational speed N of the transmission gear gradually decreases under the influence thereof. When the deviation ΔN is reversed from the negative side to the positive side at the point c, the torque fluctuation control is started again from the main torque on the positive side. When the rotational speed N of the transmission gear gradually increases and the deviation ΔN falls below the hysteresis set value −ΔN0 at the point d, torque fluctuation control is started again from the negative main torque.

  As described above, torque variation control is executed during gear engagement, and the synchro mechanism is operated in the gear engagement direction while the positive torque and the negative torque on the transmission gear are alternately applied to the transmission gear by the electric motor 3. In the torque fluctuation control, it is determined whether the main torque starts from positive or negative according to the deviation ΔN. For this reason, the rotational speed N of the transmission gear is kept near the target rotational speed Ntgt not only at the time of starting the torque fluctuation control but also during the subsequent gear engagement. Then, the transmission gear rotates in synchronization with the output shaft 2b side, and changes the phase with respect to the output shaft 2b side by slightly changing the rotational speed N with the addition of the minute torque by torque fluctuation control.

  Since engagement of dog teeth is attempted in such a situation, this situation can be resolved by a phase change of the transmission gear even if the dog teeth end by chance. Therefore, compared with the first embodiment, the dog teeth can be meshed more quickly and reliably, and the pre-selection of the shift stage can be achieved. If preselection on the gear mechanism G2 side is impossible, the power transmission on the gear mechanism G1 side must be continued, and the running performance of the vehicle will be greatly reduced. Such an unexpected situation can be prevented in advance.

Moreover, in the torque fluctuation control, when the rotational speed N of the transmission gear increases, the negative side is not the time when the deviation ΔN is reversed from the positive side to the negative side but the time when the deviation ΔN that is delayed is less than −ΔN0. The main torque has started.
Since the rotational resistance acting on the transmission gear or the like is large when the transmission 2 has a low oil temperature, even if the rotational speed N exceeds the target rotational speed Ntgt, it can be immediately below the target rotational speed Ntgt due to the rotational resistance. There is sex. In such a case, unnecessary switching of torque fluctuation control is prevented in advance, and the negative main torque can be appropriately started only when it is necessary to reduce the rotation of the transmission gear. For this reason, the rotational speed N of the transmission gear during gear engagement can be better maintained in the vicinity of the target rotational speed Ntgt.

In the torque fluctuation control, the addition of the main torque and the sub torque is repeated for the number of repetitions N, and then held at zero torque. In the torque fluctuation control, the rotational speed N of the transmission gear is slightly changed to change the phase with respect to the output shaft 2b, and this phase change contributes to the engagement of the dog teeth. However, when the phase of the speed change gear with respect to the output shaft 2b is constantly changed, there are cases where the phase where the dog teeth can mesh is instantaneously passed and cannot be meshed.
By providing a period during which the torque is maintained at zero (continuation time Tzero), the phase change of the transmission gear with respect to the output shaft 2b is interrupted during the period, and as a result, an opportunity for meshing of the dog teeth can be created. Therefore, it is possible to achieve the shift stage preselection more quickly and reliably.

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the present invention has been embodied in a hybrid truck equipped with the electric motor 3 as a driving power source in addition to the engine 1, but may be embodied in an electric vehicle equipped with only the electric motor 3, or in a bus or a passenger car. It may be embodied.
Moreover, in the said embodiment, although applied to the dual clutch transmission 2, it is not restricted to this, For example, based on a manual transmission, the automatic transmission which performs a shift operation and a clutch connection / disconnection operation automatically with an actuator It may be embodied in. Further, it may be embodied as a manual transmission, and rotation synchronization using the electric motor 3 may be performed at the time of manual shift operation by the driver.

  In the above embodiment, the target rotational speed Ntgt is always calculated based on the correction coefficients KNtemp, KNv, KNacc, and KNgear. However, the present invention is not limited to this. For example, any correction coefficient KNtemp, KNv, KNacc, KNgear may be omitted, or another correction coefficient may be added. Further, since the oil temperature Toil of the transmission 2 has the greatest influence on the rotation reduction of the transmission gear after the rotation synchronization, when the oil temperature Toil is equal to or higher than a predetermined temperature, the base value Nbase is set as the target rotation speed Ntgt, and the oil temperature Toil The target rotational speed Ntgt may be calculated based on the correction coefficients Nbase, KNtemp, KNv, KNacc, and KNgear only when is less than the predetermined temperature.

  Moreover, in the said embodiment, although torque fluctuation control was always performed irrespective of the oil temperature Toil of the transmission 2, etc., it is not restricted to this. For example, torque fluctuation control may not be executed when the oil temperature Toil of the transmission 2 is high, and torque fluctuation control may be executed only when the oil temperature Toil is low and it is difficult to mesh the dog teeth. In addition, torque fluctuation control is always executed regardless of the oil temperature Toil, and when the oil temperature Toil of the transmission 2 is high, switching of the torque fluctuation control according to the deviation ΔN is not executed, and the oil temperature Toil is low and rotational synchronization is performed. Switching of torque fluctuation control according to the deviation ΔN may be executed only when it is predicted that the subsequent reduction of the rotation of the transmission gear will be abrupt.

In the above-described embodiment, the torque fluctuation control is started again from the main torque having a large influence on the rotational speed N of the transmission gear according to the deviation ΔN, so that the rotational speed N of the transmission gear is brought close to the target rotational speed Ntgt. Although retained, it is not limited to this method. For example, the fluctuation amounts MTmain and MTsub of the main torque or the sub torque may be increased or decreased sequentially in the direction in which the rotational speed N of the transmission gear approaches the target rotational speed Ntgt based on the deviation ΔN. Further, the fluctuation times Tmain and Tsub may be increased or decreased instead of the fluctuation amounts MTmain and MTsub.
In the second embodiment, torque fluctuation control for applying a minute torque to the transmission gear is executed, and control for maintaining the rotation speed N of the transmission gear near the target rotation speed Ntgt is performed based on the deviation ΔN. However, it is not always necessary to execute the latter control, and only the torque fluctuation control may be executed.

DESCRIPTION OF SYMBOLS 1 Engine 1a Output shaft 2 Transmission 2a Input shaft 2b Output shaft 3 Electric motor 4 Inverter 5 Battery 6 Hydraulic cylinder 7 Solenoid valve 8,11 Oil path 9 Hydraulic supply source 10 Gear shift unit 12 Differential device 13 Drive shaft 14 Drive wheel 16 Vehicle ECU
(Rotation synchronization control means, target rotation speed setting means, torque fluctuation control means, torque correction means)
17 Engine ECU
18 Inverter ECU
19 Battery ECU
23, 24 Input rotational speed sensor 25 Gear position sensor 26 Accelerator pedal 27 Accelerator sensor (accelerator opening detection means)
28 Output rotation speed sensor (vehicle speed detection means)
29 Select lever 30 Lever position sensor 34 Brake pedal 35 Brake sensor 36 Oil temperature sensor (oil temperature detection means)
C1, C2 Clutch G1, G2 Gear mechanism

Claims (7)

In an electric vehicle that can travel by transmitting the driving force of the electric motor to the driving wheel side through the transmission,
When switching the gear position of the transmission, the driving force of the motor is transmitted to the transmission, and the rotational speed of the transmission gear to be switched is set based on the rotational speed on the output shaft side of the transmission Rotation synchronization control means for controlling to coincide with the first target rotation speed,
Oil temperature detecting means for detecting the oil temperature of the transmission;
And target rotation speed setting means for setting the first target rotation speed to be higher than the rotation speed on the output shaft side as the oil temperature detected by the oil temperature detection means is lower. A shift control device for an electric vehicle. Vehicle speed detection means for detecting the vehicle speed of the electric vehicle,
The said target rotational speed setting means sets the said 1st target rotational speed to the increase side rather than the rotational speed of the said output shaft side, so that the vehicle speed detected by the said vehicle speed detection means is high. 2. A shift control apparatus for an electric vehicle according to 1. Accelerator opening detection means for detecting the accelerator opening,
The target rotation speed setting means sets the first target rotation speed to be higher than the rotation speed on the output shaft side as the accelerator opening detected by the accelerator opening detection means is larger. The shift control device for an electric vehicle according to claim 1 or 2.   The target rotational speed setting means sets the first target rotational speed to be higher than the rotational speed on the output shaft side as the shift stage of the transmission is on the lower gear stage side. The shift control device for an electric vehicle according to any one of claims 1 to 3.   Torque fluctuation control in which positive and negative minute torques are alternately applied to the transmission gear by the electric motor around the zero torque capable of maintaining the rotational speed of the transmission gear after completion of the rotation synchronization by the rotation synchronization control means. 5. The shift control apparatus for an electric vehicle according to claim 1, further comprising torque fluctuation control means for executing During the execution of the torque fluctuation control by the torque fluctuation control means, the torque fluctuation is controlled in order to keep the rotation speed of the transmission gear near the second target rotation speed set corresponding to the rotation speed on the output shaft side. Torque correcting means for correcting the positive and negative minute torques added by the control means;
The torque correcting means corrects the positive minute torque to be larger than the negative minute torque with respect to the zero torque when the rotational speed of the transmission gear is lower than the second target rotational speed. When the rotational speed of the transmission gear exceeds the second target rotational speed by a preset hysteresis setting value, the negative minute torque is greater than the positive minute torque with reference to the zero torque. The shift control device for an electric vehicle according to claim 5, wherein the shift control device corrects as follows.   7. The electric vehicle shift according to claim 5, wherein the torque fluctuation control means continues the zero torque for a preset duration between the positive and negative minute torques. Control device.

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