JP5993391B2 - Transmission and control method thereof - Google Patents

Description

  The present invention relates to control of a transmission mounted on a vehicle.

  A CVT such as a belt continuously variable transmission is a transmission capable of continuously changing a transmission gear ratio. However, a number of transmission gear ratios to be used are set in advance to increase the vehicle speed of a vehicle equipped with the CVT. As the CVT target gear ratio is changed in order from the gear ratio set to the Low side to the gear ratio set to the High side, a gear shift close to the conventional step AT (hereinafter referred to as an AT-like gear shift). Can be realized (Patent Document 1).

  According to such AT-like shift, since the increase in the rotational speed of the power source such as the engine and the increase in the vehicle speed are linked, it can be matched with the driver's feeling. In addition, the low-side gear ratio is maintained until the input rotational speed of the CVT reaches the upper limit during start-up and acceleration, so that the driving force of the vehicle can be secured and the start-up performance and acceleration performance can be improved.

JP-A-5-332426

  In an AT-like shift, if an upshift is attempted at a speed similar to that of the conventional step AT, an undershoot occurs in which the actual speed ratio of the CVT exceeds the target speed ratio and changes to the High side. In the reference example shown in FIG. 8, at time t31, the target gear ratio is changed from the first gear ratio (the gear ratio corresponding to the first gear of step AT, the same shall apply hereinafter) to the second gear gear ratio. It has occurred.

  This is because, during an upshift, an inertia torque is generated due to a decrease in the primary rotation speed of the CVT, and this inertia torque reduces the rotation speed of a power source such as an engine. This is because the rotational speed of the power source is greatly reduced and the primary rotational speed of the CVT is further lowered from the rotational speed corresponding to the target gear ratio.

  When an undershoot occurs, the actual speed ratio is changed to the Low side in order to return the actual speed ratio to the target speed ratio, that is, a downshift is performed (after time t33 in FIG. 8). And a bump feel (deceleration G) occur, causing the driver to feel uncomfortable.

  The present invention has been made in view of such technical problems, and it is an object of the present invention to suppress a blast of a power source and a bump feel when an undershoot occurs during an AT-like shift.

  According to an aspect of the present invention, a variator that is mounted on a vehicle and that shifts the output rotation of a power source and outputs it to drive wheels, and a value that causes the target gear ratio to become higher than the previous value as the vehicle speed increases. And an upshift control means for controlling the variator so that the actual speed ratio becomes the target speed ratio, and the upshift control means is configured so that the actual speed ratio exceeds the target speed ratio and is high. When the undershoot that changes to the side occurs, the target speed change ratio is updated to the actual speed change ratio at the time when the change direction of the actual speed change ratio changes from the High side to the Low side. A machine is provided.

  According to another aspect of the present invention, a transmission control method corresponding to this is provided.

  According to these aspects, even if an undershoot occurs, a downshift for bringing the actual gear ratio close to the original target gear ratio is not performed. The deceleration G) can be suppressed, and the uncomfortable feeling that they give to the driver can be suppressed.

1 is a schematic configuration diagram of a vehicle equipped with a transmission according to an embodiment of the present invention. It is the flowchart which showed the contents of upshift control. It is the figure which showed a mode that AT-like gear shifting was performed. It is the flowchart which showed the contents of the target gear ratio update / correction control at the time of undershoot occurrence. It is a table for calculating a correction amount. It is a time chart for demonstrating the effect of this embodiment. It is a time chart for demonstrating the effect of this embodiment. It is a time chart which showed the mode at the time of undershoot occurrence.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, “speed ratio” is a value obtained by dividing the input rotational speed of the transmission by the output rotational speed of the transmission.

  FIG. 1 shows a schematic configuration of a vehicle equipped with a variator 20 according to an embodiment of the present invention. This vehicle includes an engine 1 as a power source. The output rotation of the engine 1 is transmitted to the drive wheels 7 via the torque converter 2, the first gear train 3, the transmission 4, the second gear train 5, and the differential device 6. The second gear train 5 is provided with a parking mechanism 8 that mechanically locks the output shaft of the transmission 4 at the time of parking.

  The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine, and the rotation speed and torque are controlled by the engine controller 50.

  The torque converter 2 includes a lockup clutch 2a. When the lockup clutch 2a is engaged, slippage in the torque converter 2 is eliminated, and the transmission efficiency of the torque converter 2 can be improved.

  Further, the vehicle includes an oil pump 10 that is driven using a part of the power of the engine 1, a hydraulic control circuit 11 that adjusts the hydraulic pressure from the oil pump 10 and supplies the hydraulic pressure to each part of the transmission 4, A transmission controller 12 that controls the hydraulic control circuit 11 is provided.

  The transmission 4 is a transmission that includes a variator 20 and an auxiliary transmission mechanism 30 provided in series with the variator 20. “Provided in series” means that the variator 20 and the auxiliary transmission mechanism 30 are provided in series in the power transmission path from the engine 1 to the drive wheels 7.

  The variator 20 includes a primary pulley 21, a secondary pulley 22, and a belt 23 that is wound around the pulleys 21 and 22. Each of the pulleys 21 and 22 includes a fixed conical plate, a movable conical plate that is arranged with a sheave surface facing the fixed conical plate, and forms a V-groove between the fixed conical plate, and the movable conical plate. And a hydraulic cylinder that displaces the movable conical plate in the axial direction.

  When the hydraulic pressure (primary pressure and secondary pressure) supplied to the pulleys 21 and 22 is adjusted, the force with which the pulleys 21 and 22 hold the belt 23 changes, and the torque capacity (maximum torque that can be transmitted) of the variator 20 changes. Further, the width of the V-groove changes, the contact radius between the belt 23 and the pulleys 21 and 22 changes, and the transmission ratio of the variator 20 changes steplessly.

  The subtransmission mechanism 30 is a transmission having two forward speeds and one reverse speed. The sub-transmission mechanism 30 is connected to a Ravigneaux type planetary gear mechanism 31 in which two planetary gear carriers are connected, and a plurality of friction elements connected to a plurality of rotating elements constituting the Ravigneaux type planetary gear mechanism 31 to change their linkage state. Elements (Low brake 32, High clutch 33, Rev brake 34). The gear position of the subtransmission mechanism 30 is changed by adjusting the hydraulic pressure supplied to the friction elements 32 to 34 and changing the engagement state of the friction elements 32 to 34.

  The transmission controller 12 includes a CPU, a storage device including a RAM / ROM, an input interface, an output interface, and a bus that interconnects them.

  The transmission controller 12 detects an output signal of an accelerator opening sensor 41 that detects an accelerator opening APO that represents an operation amount of an accelerator pedal, and a rotation speed (primary rotation speed) of the primary pulley 21 via an input interface. The output signal of the rotational speed sensor 42, the output signal of the vehicle speed sensor 43 that detects the vehicle speed VSP, the output signal of the hydraulic sensor 44 that detects the secondary pressure, the output signal of the inhibitor switch 45 that detects the position of the select lever, An output signal of a rotation speed sensor 46 that detects a rotation speed (secondary rotation speed) is input.

  The storage device of the transmission controller 12 stores a shift control program for the transmission 4 and a shift map used in the shift control program. The transmission controller 12 reads out and executes a shift control program stored in the storage device, performs various arithmetic processes on various signals input via the input interface, and supplies them to each part of the transmission 4. An instruction value for oil pressure is set, and the set instruction value is output to the oil pressure control circuit 11 via the output interface. Various values used in the calculation process by the transmission controller 12 and the calculation results are appropriately stored in the storage device.

  The hydraulic control circuit 11 includes a plurality of flow paths and a plurality of hydraulic control valves. The oil pressure control circuit 11 controls a plurality of oil pressure control valves based on the instruction value from the transmission controller 12 to switch the oil pressure supply path, and uses the oil pressure generated by the oil pump 10 as a base pressure to respond to the instruction value. Is supplied to each part of the transmission 4. As a result, the variator 20 is shifted, the shift stage of the auxiliary transmission mechanism 30 is changed, the capacities of the friction elements 32 to 34 are controlled, and the lockup clutch 2a is engaged and released.

  As described above, the variator 20 is a speed change mechanism that can change the speed ratio steplessly. However, in the present embodiment, the transmission controller 12 is configured to change the speed of the conventional step AT (for example, the first speed to the first speed). The gear ratio corresponding to the fifth gear) is set in advance as a gear ratio to be used, and when a predetermined upshift condition is satisfied, the target gear ratio is shifted to the High side (smaller side) than the target gear ratio at that time. By sequentially changing to the ratio, a shift (AT-like shift) close to the conventional step AT is realized.

  FIG. 2 is a flowchart showing the contents of the upshift control by the transmission controller 12.

  In the upshift control, the transmission controller 12 determines whether the upshift condition is satisfied (S11), and when it is determined that the upshift condition is satisfied, the target gear ratio of the variator 20 is set to the target shift ratio at that time. The variator 20 is controlled so that the actual gear ratio of the variator 20 becomes the target gear ratio by changing to a gear ratio that is farther to the High side than the ratio (S12). During the upshift of the variator 20 by the AT-like shift, the shift of the auxiliary transmission mechanism 30 is prohibited.

  The upshift condition is satisfied, for example, when the actual primary rotational speed exceeds the upshift rotational speed set according to the accelerator opening APO or the like, or when the driver performs an upshift operation with a select lever or the like. To be judged.

  FIG. 3 shows a state in which an AT-like shift is performed. In this example, when the actual primary rotation speed reaches the upshift rotation speed, the target transmission gear ratio is sequentially changed (upshifted) to the high gear ratio. Yes.

  According to the AT-like shift, since the increase in the rotational speed of the engine 1 and the increase in the vehicle speed are interlocked as in the conventional step AT, it is possible to match the driver's feeling. Moreover, since the low gear ratio is maintained until the actual primary rotational speed reaches the upshift rotational speed at the time of start and acceleration, the driving force of the vehicle can be ensured and the start performance and acceleration performance can be improved.

  However, if an AT-like shift is attempted to upshift at the same speed as the conventional step AT, an undershoot occurs in which the actual gear ratio of the variator 20 exceeds the target gear ratio and changes to the High side (see FIG. 8). ). If a downshift is performed to bring the actual gear ratio closer to the target gear ratio when an undershoot occurs, the engine 1 is blown up and a bump feel (deceleration G) occurs, which may cause the driver to feel uncomfortable. Absent.

  Therefore, the transmission controller 12 performs the target speed ratio update / correction control shown in FIG. 4 so as to suppress the engine blow-up and the bump feel (deceleration G) after the undershoot occurs.

  According to this, first, in S21, the transmission controller 12 determines whether the control conditions for the target gear ratio update / correction control are satisfied. The control condition of the target gear ratio update / correction control is, for example, within a predetermined time from execution of upshift by AT-like shift, and the time change rate of the accelerator opening APO is less than a predetermined value (the accelerator opening is substantially constant). It is judged that it was established. If it is determined that the target transmission ratio update / correction control condition is satisfied, the process proceeds to S22, and if not, the process ends.

  In S22, the transmission controller 12 calculates an undershoot amount. The undershoot amount can be calculated by subtracting the actual primary rotation speed from the target primary rotation speed obtained by multiplying the actual secondary rotation speed by the target gear ratio.

  In S23, the transmission controller 12 calculates the time change rate of the actual primary rotational speed.

  In S24, the transmission controller 12 determines whether the change direction of the actual gear ratio has changed from the High side to the Low side. This determination can be made based on whether the temporal change rate of the actual primary rotation speed is smaller than a predetermined minute value. If it is determined that the change direction of the actual gear ratio has changed from the High side to the Low side, the process proceeds to S25.

  In S25, the transmission controller 12 determines whether the undershoot amount calculated in S22 is larger than the first threshold value. If the undershoot amount is greater than the first threshold, the process proceeds to S26. When the undershoot amount is smaller than the first threshold value, it is less necessary to perform the target gear ratio update / correction control, and thus the process ends.

  In S26, the transmission controller 12 changes the actual speed ratio when the direction of change of the actual speed ratio changes from the High side to the Low side, that is, the actual speed ratio changes from the target speed ratio to the High side due to undershoot. The actual gear ratio at the time of the change to the highest side is set as the updated target gear ratio.

  In S27, the transmission controller 12 updates the target gear ratio to the updated target gear ratio set in S26.

  In S28, the transmission controller 12 determines whether the undershoot amount calculated in S22 is greater than a second threshold value that is greater than the first threshold value. When the undershoot amount is smaller than the second threshold value, the target gear ratio is maintained at the value set in S27. However, when the undershoot amount is larger than the second threshold value, the process proceeds to S29 and after, and the target gear ratio is S27. It is set to a value corrected further to the Low side from the set value.

  Specifically, the transmission controller 12 turns on a correction flag indicating that the target gear ratio needs to be corrected in S29, and calculates a correction amount with reference to the map shown in FIG. 5 in S30. . The correction amount is calculated based on the vehicle speed VSP and the accelerator opening APO, and a larger value is set as the vehicle speed VSP is lower and as the accelerator opening APO is larger. Then, the transmission controller 12 calculates the corrected target gear ratio by adding the correction amount calculated in S30 to the updated target gear ratio set in S26 (S31).

  This is because when the undershoot amount is larger than the second threshold, the actual speed ratio is significantly higher than the target speed ratio, and in order to obtain sufficient acceleration performance, the actual speed ratio is set to the Low side. It is preferable that the speed is closer, and that the driver's request for acceleration is greater as the vehicle speed VSP is lower and the accelerator opening APO is larger, and it is preferable that the gear ratio be set to the lower side.

  Further, if the target speed ratio is maintained at the value updated in S27 when the undershoot amount is larger than the second threshold, the difference between the actual speed ratio and the target speed ratio in the next upshift becomes small. Even if the actual primary rotational speed reaches the upshift rotational speed and the next upshift is performed, the actual primary rotational speed reaches the upshift rotational speed again within a short period of time, and a further upshift is performed. This is because it causes a sense of incongruity (shift busy feeling).

  On the other hand, if it is not determined in S24 that the change direction of the actual gear ratio has changed from the High side to the Low side, the process proceeds to S32.

  In S32, the transmission controller 12 determines whether or not the target gear ratio update / correction control is complete. Specifically, when the upshift condition is satisfied (YES in S11), or when it is determined that the time change rate of the accelerator opening APO exceeds a predetermined value and the accelerator pedal is depressed, the transmission controller 12 determines that the target gear ratio update / correction control is to be terminated, turns off the correction flag, and terminates the processing (S34).

  If not, the process proceeds to S33, and the transmission controller 12 determines whether the correction flag is ON. If the correction flag is ON, the process proceeds to S30, and the target gear ratio is further corrected. If the vehicle speed VSP has increased since the previous execution, a larger correction amount is obtained according to the map shown in FIG. Is set, and the target gear ratio is further corrected to the Low side.

  On the other hand, when the correction flag is OFF, the processing is ended as it is, and the target gear ratio is maintained at the value set in S27.

  Then, the effect by performing the said target gear ratio update and correction control is demonstrated.

  FIG. 6 shows a state in which the actual primary rotational speed reaches the upshift rotational speed and the upshift is executed during acceleration at the first speed gear ratio (speed ratio corresponding to the first speed of the step AT). Yes.

  When the actual primary rotational speed reaches the upshift rotational speed at time t11, the target speed ratio of the variator 20 is changed from the 1st speed ratio to the 2nd speed ratio that is higher than the 1st speed ratio, and the variator 20 is increased. A shift is performed.

  The actual primary rotation speed changes toward the target primary rotation speed obtained by multiplying the actual secondary rotation speed by the target gear ratio, but even after reaching the target primary rotation speed at time t12, the actual primary rotation speed is affected by inertia. Continues to decrease, and undershoot occurs in which the actual gear ratio exceeds the target gear ratio and becomes High.

  However, at time t13, when the direction of change of the actual gear ratio changes from the High side to the Low side, the target gear ratio is updated to the actual gear ratio (updated target gear ratio) at that time, and the undershoot amount exceeds the second threshold value. Is smaller, the target gear ratio is maintained at that value even after time t13.

  Therefore, according to the target gear ratio update / correction control, even if an undershoot occurs, no downshift is performed to bring the actual gear ratio closer to the original target gear ratio (second speed gear ratio in this example). Therefore, it is possible to suppress the racing of the engine 1 and the bump feel (deceleration G) caused by the downshift, and to suppress the uncomfortable feeling that these give to the driver (effect corresponding to claims 1 and 4).

  FIG. 7 is also similar to FIG. 6 when the actual primary rotational speed reaches the upshift rotational speed and the upshift is executed during acceleration at the first speed gear ratio (speed ratio corresponding to the first speed of the step AT). Although the situation is shown, the undershoot amount is larger than the second threshold value.

  At time t21, the variator 20 is upshifted, and undershoot has occurred at time t22.

  When the change direction of the actual speed ratio changes from the High side to the Low side at time t23, the target speed ratio is updated to the actual speed ratio (update target speed ratio) at that time, and the target speed ratio is then set to the vehicle speed VSP. As it increases, it is corrected to the Low side.

  When the undershoot amount is larger than the second threshold, if the target speed ratio is maintained at the actual speed ratio when the change direction of the actual speed ratio changes from the high side to the low side, the actual speed ratio remains on the high side. Therefore, sufficient acceleration performance cannot be obtained. Also, there may be a problem that the interval between the next upshift and the next upshift is shortened.

  However, if the target gear ratio is corrected to the low side as the vehicle speed VSP increases, these problems can be prevented (effects corresponding to claims 2 and 3).

  Even if the target gear ratio is corrected to the Low side, the downshift is gentle compared to the downshift when the actual gear ratio is returned to the original target gear ratio, and the engine 1 is blown due to the downshift. The rise and bump feel (deceleration G) can be sufficiently suppressed.

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  For example, in the above embodiment, when the undershoot amount is smaller than the second threshold, the target gear ratio is maintained at the actual gear ratio at the time when the change direction of the actual gear ratio changes from the High side to the Low side. If it is larger than 2 threshold values, this value is corrected to the Low side as the vehicle speed increases. However, it may be simplified and either one of the processes may be performed regardless of the undershoot amount.

  Further, the target speed ratio update / correction control is executed only when upshifting from the first speed ratio to the second speed ratio where the target speed ratio change amount before and after the upshift is large and the undershoot amount is large. It may be.

  In the above embodiment, the auxiliary transmission mechanism 30 is disposed on the output side of the variator 20, but the auxiliary transmission mechanism 30 is not essential.

  In the above embodiment, the variator 20 is a belt continuously variable transmission. However, the variator 20 may be a continuously variable transmission that generates undershoot when upshifting is performed by AT-like shift. It is not limited to a transmission.

1 Engine (Power source)
4 Transmission 12 Transmission controller (upshift control means)
20 Variator

Claims (4)

A variator mounted on the vehicle, shifting the output rotation of the power source and outputting it to the drive wheels;
An upshift control means for controlling the variator so that the actual gear ratio becomes the target gear ratio by changing the target gear ratio to a value that is higher than the previous value as the vehicle speed increases;
With
When an undershoot occurs in which the actual speed ratio exceeds the target speed ratio and changes to the High side, the upshift control means changes the target speed ratio from the High side when the change direction of the actual speed ratio is Low. Update to the actual gear ratio at the time of turning to the side,
A transmission characterized by that. The transmission according to claim 1,
The upshift control means corrects the updated target gear ratio to the Low side as the vehicle speed increases.
A transmission characterized by that. The transmission according to claim 2,
The upshift control means increases the vehicle speed when a deviation between the actual speed ratio and the target speed ratio when the change direction of the actual speed ratio changes from the High side to the Low side is larger than a predetermined value. Accordingly, the updated target gear ratio is corrected to the Low side,
A transmission characterized by that. A control method for a transmission that is mounted on a vehicle and includes a variator that shifts the output rotation of a power source and outputs it to drive wheels,
As the vehicle speed increases, the target gear ratio is changed to a value that is higher than the previous value, and the variator is controlled so that the actual gear ratio becomes the target gear ratio.
When an undershoot occurs in which the actual speed ratio exceeds the target speed ratio and changes to the High side, the target speed ratio changes to the target speed ratio when the actual speed ratio changes from the High side to the Low side. Update to actual gear ratio,
A control method for a transmission.

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