Automatic transmission, automatic transmission control method and program

Abstract

An automatic transmission according to the present invention is capable of upshifting while the engine speed is high when a driver's acceleration request is large. The automatic transmission comprises a torque converter disposed downstream of a drive source in a power transmission path and having a lockup clutch; and a speed change mechanism disposed downstream of the torque converter and configured to change the speed ratio between an input shaft and an output shaft. With the lockup clutch engaged, the automatic transmission initiates an upshift when the input shaft speed reaches a first speed. With the lockup clutch disengaged or slipping, the automatic transmission initiates an upshift when the input shaft speed reaches a second speed obtained by subtracting a first predetermined speed from the first speed. The first predetermined speed decreases as the output torque of the drive source increases.

Description

Technical Field

[0001] The present invention relates to an automatic transmission, a control method and a program for the automatic transmission. Background Art

[0002] Patent Document 1 discloses a vehicle control device that changes the shift line used for shifting an automatic transmission at wide-open throttle based on whether the engine speed can be controlled by an engine rotation control unit. This control device performs a shift when the engine speed is higher when the engine speed can be controlled, compared to when the engine speed cannot be controlled.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-218785

[0006] Problems to be solved by the invention

[0007] However, when the lockup clutch is released or slipping, a difference occurs between the engine speed and the speed of the transmission's input shaft. Therefore, when performing an upshift based on the speed of the transmission's input shaft, to prevent an excessive increase in engine speed, it is necessary to consider the speed difference and perform the upshift at a low engine speed. Consequently, even when the driver's acceleration request is strong, an upshift may not be performed at a high engine speed. Summary of the Invention

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to perform an upshift while the engine speed is high when the driver's acceleration request is large.

[0009] According to one embodiment of the present invention, an automatic transmission comprises: a torque converter, which is arranged downstream of a driving source in a power transmission path and has a lockup clutch; a speed change mechanism, which is arranged downstream of the torque converter and changes the speed ratio between an input shaft and an output shaft, wherein when the rotational speed of the input shaft reaches a first rotational speed when the lockup clutch is engaged, upshifting begins; and when the rotational speed of the input shaft reaches a second rotational speed obtained by subtracting a first predetermined rotational speed from the first rotational speed when the lockup clutch is released or slipping, upshifting begins, wherein the first predetermined rotational speed decreases as the output torque of the driving source increases.

[0010] Effects of the Invention

[0011] In the above embodiment, when the engine output torque is high, the first predetermined speed is low. Therefore, since upshifting occurs while the engine speed is higher, the gear shift can be performed after the engine speed is increased to a level that meets the driver's acceleration request. Therefore, when the driver's acceleration request is high, upshifting can be performed while the engine speed is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of a vehicle equipped with an automatic transmission according to an embodiment of the present invention.

[0013] Figure 2 This is a flowchart showing the speed change control process during acceleration performed by the transmission controller.

[0014] Figure 3 This is a diagram conceptually illustrating the upshift determination rotation speed.

[0015] Figure 4 This is a timing chart explaining the speed change control during acceleration.

[0016] Figure 5 This is a diagram conceptually illustrating the predicted vehicle speed.

[0017] Figure 6 This is a flowchart showing the delay control based on the pre-read vehicle speed performed by the transmission controller.

[0018] Figure 7 This is a diagram conceptually illustrating delay control based on the pre-read vehicle speed.

[0019] Figure 8 This is to explain the further application of delay control based on pre-read vehicle speed to Figure 4 This is a timing diagram of the speed change control during acceleration. DETAILED DESCRIPTION

[0020] The following describes embodiments of the present invention with reference to the accompanying drawings. Hereinafter, a large speed ratio is referred to as a low gear (Low), and a small speed ratio is referred to as a high gear (High). Furthermore, changing the speed ratio toward a low gear (Low) is referred to as a downshift, and changing it toward a high gear (High) is referred to as an upshift.

[0021] Figure 1 1 is a schematic structural diagram of a vehicle 100 equipped with an automatic transmission 20 according to an embodiment of the present invention. Figure 1 As shown, vehicle 100 includes an engine 10 as a driving source, an automatic transmission 20 , an engine controller 30 , and a transmission controller 40 .

[0022] The automatic transmission 20 includes a torque converter 2 , a forward / reverse switching mechanism 3 as a power transmission mechanism, a speed change mechanism 4 as a speed change mechanism, a hydraulic control circuit 5 , and an oil pump 6 .

[0023] In vehicle 100 , rotation generated by engine 10 is transmitted to drive wheels 50 via a power transmission path formed by torque converter 2 , forward / reverse switching mechanism 3 , speed change mechanism 4 , gear set 7 , and differential gear device 8 .

[0024] The torque converter 2 is located downstream of the engine 10 in the power transmission path. A lockup clutch 2a is provided on the torque converter 2. When the lockup clutch 2a is engaged, the input shaft 2b, which serves as the input element of the torque converter 2, and the output shaft 2c, which serves as the output element, are directly connected, and the input shaft 2b and the output shaft 2c rotate at the same speed. Therefore, when the lockup clutch 2a is engaged, the rotation of the output shaft 10a of the engine 10 is directly transmitted to the forward / reverse switching mechanism 3 via the output shaft 2c of the torque converter 2.

[0025] The forward-reverse switching mechanism 3 is primarily composed of a double-pinion planetary gear set, whose sun gear is coupled to the engine 10 via the torque converter 2, and whose planetary carrier is coupled to the input shaft 4d (primary pulley 4a) of the speed change mechanism 4. The forward-reverse switching mechanism 3 also includes a forward clutch 3a that directly connects the sun gear of the double-pinion planetary gear set to the planetary carrier, and a reverse brake 3b that secures the ring gear. When the forward clutch 3a is engaged, the input rotation from the engine 10 via the torque converter 2 is directly transmitted unchanged to the primary pulley 4a. When the reverse brake 3b is engaged, the input rotation from the engine 10 via the torque converter 2 is reversed, decelerated, and then transmitted to the primary pulley 4a.

[0026] The speed change mechanism 4 is positioned downstream of the engine 10 and the torque converter 2 in the power transmission path. The speed change mechanism 4 continuously changes the speed of the engine 10's rotation, which is transmitted to the input shaft 4d, and transmits it to the drive wheels 50 via the output shaft 4e. Specifically, the speed change mechanism 4 continuously changes the speed ratio between the input shaft 4d and the output shaft 4e. The speed change mechanism 4 includes a primary pulley 4a provided on the engine 10 side of the power transmission path; a secondary pulley 4b provided on the drive wheels 50 side; and a belt 4c, an endless member, wound around the primary and secondary pulleys 4a, 4b.

[0027] In the speed change mechanism 4, the oil pressure supplied to the primary pulley 4a and the oil pressure supplied to the secondary pulley 4b are controlled to change the contact radius between the pulleys 4a and 4b and the belt 4c, thereby changing the speed ratio. The belt 4c contacts the pulley surfaces 4f and 4g of the pulleys 4a and 4b, respectively, transmitting power between the primary pulley 4a and the secondary pulley 4b.

[0028] The oil pump 6 is a mechanical oil pump that is input with the rotation of the engine 10 and is driven by a part of the power of the engine 10. The oil discharged from the oil pump 6 is supplied to the hydraulic control circuit 5.

[0029] The oil pressure control circuit 5 includes: a regulating valve 5a that adjusts the pressure of the working oil supplied from the oil pump 6 and generates the necessary oil pressure, a primary solenoid valve 5b that adjusts the oil pressure supplied to the primary pulley 4a, a secondary solenoid valve 5c that adjusts the oil pressure supplied to the secondary pulley 4b, a locking solenoid valve 5d that adjusts the oil pressure supplied to the locking clutch 2a, a selection solenoid valve 5e that adjusts the oil pressure supplied to the forward clutch 3a and the oil pressure supplied to the reverse brake 3b, a manual valve 5f that switches the supply path of the oil pressure to the forward clutch 3a and the reverse brake 3b, etc.

[0030] The hydraulic control circuit 5 supplies regulated hydraulic pressure to the torque converter 2 , the forward / reverse switching mechanism 3 , and the speed change mechanism 4 based on a control signal from the transmission controller 40 .

[0031] The engine controller 30 is composed of a microcomputer including a CPU, RAM, ROM, an input / output interface, etc. The engine controller 30 performs various processes by the CPU reading and executing programs stored in the ROM. The engine controller 30 may also be composed of a plurality of microcomputers.

[0032] The engine controller 30 controls the rotation speed, torque, and the like of the engine 10 based on signals from various sensors that detect the states of various parts of the vehicle 100 .

[0033] The transmission controller 40 is comprised of a microcomputer equipped with a CPU, RAM, ROM, and input / output interfaces, and is communicatively connected to the engine controller 30. The CPU reads and executes programs stored in the ROM to perform various processes. The transmission controller 40 may also be comprised of multiple microcomputers. Alternatively, the transmission controller 40 and the engine controller 30 may be combined into a single controller.

[0034] The transmission controller 40 controls the engagement state of the lockup clutch 2 a , the speed ratio of the speed change mechanism 4 , the engagement states of the forward clutch 3 a and the reverse brake 3 b , and the like based on signals from various sensors that detect the states of various parts of the vehicle 100 .

[0035] Input to the transmission controller 40 are: a signal from an accelerator pedal opening sensor 61 that detects an accelerator pedal opening APO, a signal from a brake hydraulic pressure sensor 62 that detects a brake hydraulic pressure BRP corresponding to the amount of operation of the brake pedal, a signal from a circuit breaker 64 that detects the position of a shift device 63, a signal from a turbine speed sensor 65 that detects a rotational speed Nt of an output shaft 2c of the torque converter 2, a signal from a primary speed sensor 66 that detects a rotational speed Np of an input shaft 4d (primary pulley 4a) of the speed change mechanism 4, a signal from a secondary speed sensor 67 that detects a rotational speed Ns of an output shaft 4e (secondary pulley 4b) of the speed change mechanism 4, a signal from a primary oil pressure sensor 68 that detects a primary oil pressure Pp supplied to the primary pulley 4a, a signal from a secondary oil pressure sensor 69 that detects a secondary oil pressure Ps supplied to the secondary pulley 4b, and the like.

[0036] Next, refer to Figures 2 to 4 Next, the speed change control process during acceleration performed by the transmission controller 40 will be described. The speed change control process is performed by the transmission controller 40 at regular intervals.

[0037] First, refer to Figure 2 and Figure 3 Next, the processing of the speed change control during acceleration performed by the transmission controller 40 will be described. Figure 2 This is a flowchart showing the speed change control process during acceleration performed by the transmission controller 40 . Figure 3 This is a diagram conceptually showing the upshift determination rotation speed.

[0038] The speed change control during acceleration is performed when the driver's acceleration request is large, for example, when the driver steps on the accelerator pedal to fully accelerate the vehicle 100. Here, the automatic transmission 20 is a continuously variable transmission that performs stepwise speed change control like a stepped transmission.

[0039] In the torque converter 2, when the lockup clutch 2a is engaged, the rotational speed of the input shaft 2b (the rotational speed of the engine 10) and the rotational speed of the output shaft 2c (the rotational speed of the input shaft 4d of the speed change mechanism 4) are equal. On the other hand, when the lockup clutch 2a is not engaged, the rotational speed of the input shaft 2b is higher than the rotational speed of the output shaft 2c. In the automatic transmission 20, upshift determination is based on the rotational speed of the input shaft 4d. However, when the lockup clutch 2a is not engaged, upshift determination is made with a margin corresponding to the speed difference between the input shaft 2b and the output shaft 2c to prevent excessive increases in the engine 10 rotational speed.

[0040] However, for example, just before the lockup clutch 2a is fully engaged (in a slipping state), the speed difference between the input shaft 2b and the output shaft 2c is smaller than when the lockup clutch 2a is released. In other words, the speed difference between the input shaft 2b and the output shaft 2c varies depending on the degree of engagement of the lockup clutch 2a. Therefore, just before the lockup clutch 2a is fully engaged, similar to the case when the lockup clutch 2a is released, if an upshift is performed with a margin corresponding to the speed difference between the input shaft 2b and the output shaft 2c, there is a risk that the upshift will occur while the engine 10 speed is low. Therefore, in the automatic transmission 20, the speed change control during acceleration is performed as follows, taking into account the degree of engagement of the lockup clutch 2a.

[0041] exist Figure 2 In step S11, the transmission controller 40 detects the current actual slip speed of the torque converter 2. Specifically, the transmission controller 40 detects the speed of the input shaft 2b based on a signal from the engine controller 30, and detects the speed of the output shaft 2c based on a signal from the turbine speed sensor 65. The speed difference between the input shaft 2b and the output shaft 2c is used as the actual slip speed.

[0042] In step S12 , the transmission controller 40 detects the output torque of the engine 10 based on the signal from the engine controller 30 .

[0043] In step S13 , the residual slip speed of the torque converter 2 that may occur is calculated. The residual slip speed is calculated based on the difference between the current output torque of the engine 10 and the maximum torque (the residual output torque) and the fluid characteristics of the torque converter 2 .

[0044] Specifically, the greater the difference between the current output torque of the engine 10 and the maximum torque, the greater the slip speed of the torque converter 2 that is likely to occur when the accelerator pedal is further depressed. In other words, the greater the current output torque of the engine 10, the smaller the difference from the maximum torque, and thus the smaller the slip speed of the torque converter 2 that is likely to occur when the accelerator pedal is further depressed. Therefore, the residual slip speed is set to decrease as the current output torque of the engine 10 increases.

[0045] In step S14, the transmission controller 40 subtracts the actual slip speed detected in step S11 and the residual slip speed calculated in step S13 from the upper limit speed (LU upper limit PRI speed) of the primary pulley 4a in the engaged state of the lockup clutch 2a to calculate the upshift determination speed.

[0046] Specifically, if Figure 3As shown, the engine 10 speed is higher than the primary pulley 4a speed (PRI speed) by the current actual slip speed. Therefore, the upshift determination speed is determined by subtracting the current actual slip speed and the residual slip speed of the torque converter 2 that may result from this from the LU upper limit PRI speed. The LU upper limit PRI speed is set lower than the maximum speed of the engine 10 to prevent excessive increases in the engine 10 speed.

[0047] When the lockup clutch 2a is engaged, the actual slip rotation speed and the residual slip rotation speed are both 0. Therefore, the upshift determination rotation speed is the same as the LU upper limit PRI rotation speed.

[0048] return Figure 2 In step S15, the transmission controller 40 determines whether the target primary pulley speed (target PRI speed) is equal to or greater than the upshift determination speed. If it is determined in step S15 that the target PRI speed is equal to or greater than the upshift determination speed, the process proceeds to step S16. On the other hand, if it is determined in step S15 that the target PRI speed is not equal to or greater than the upshift determination speed, that is, if the target PRI speed is lower than the upshift determination speed, the process of steps S11 to S15 is repeated.

[0049] In step S16, the transmission controller 40 determines to execute an upshift. Then, in step S17, the transmission controller 40 executes an upshift of the automatic transmission 20. Specifically, the transmission controller 40 executes an upshift until the PRI speed reaches a speed corresponding to one or more gear steps.

[0050] Next, refer to Figure 4 , the speed change control during acceleration performed by the transmission controller 40 will be described in detail. Figure 4 This is a timing chart explaining the speed change control during acceleration.

[0051] exist Figure 4 In the figure, the horizontal axis is time [sec], and the vertical axis represents the accelerator pedal opening APO, vehicle speed [km / h], target primary pulley speed (target PRI speed: dotted line) [rpm], engine speed (solid line) [rpm], primary pulley speed (PRI speed: thin solid line) [rpm], target primary pulley speed of the comparison example (target PRI speed: thin dotted line) [rpm], target speed ratio (dotted line), and actual speed ratio (solid line).

[0052] The target PRI speed of the comparative example does not apply the present embodiment, but instead uses two thresholds for upshift determination: when the lockup clutch 2a is engaged and when it is not engaged. Specifically, when the lockup clutch 2a is engaged, the lockup upper limit primary pulley speed (LU upper limit PRI speed) is used as the threshold, while when the lockup clutch 2a is not engaged, the unlocking upper limit primary pulley speed (UnLU upper limit PRI speed) is used as the threshold.

[0053] At time T11, in the automatic transmission of the comparative example, the target PRI speed reaches the UnLU upper limit PRI speed, so the transmission controller 40 makes an upshift determination. Similarly, at time T12, the target PRI speed reaches the UnLU upper limit PRI speed, so the transmission controller 40 makes an upshift determination.

[0054] Thus, in the automatic transmission of the comparative example, the upshift determination is performed and the upshift is executed before the rotation speed of the engine 10 becomes sufficiently high. Therefore, the engine 10 cannot be used at a high rotation speed.

[0055] In contrast, in the automatic transmission 20 of this embodiment, the upshift determination speed obtained by subtracting the current actual slip speed and the residual slip speed of the torque converter 2 that may result from it from the LU upper limit PRI speed of the primary pulley 4a when the lockup clutch 2a is engaged is set as the threshold.

[0056] At time T21, the target PRI speed reaches the upshift determination speed, so the transmission controller 40 performs an upshift determination. Specifically, with the lockup clutch 2a released or slipping, an upshift is initiated when the speed of the input shaft 2b reaches the upshift determination speed obtained by subtracting the current actual slip speed and the residual slip speed of the torque converter 2 that may result from this from the LU upper limit PRI speed. Thus, since the upshift determination is performed when the engine 10 speed has increased compared to time T11, the upshift is executed at time T22 after the engine 10 speed reaches a sufficiently high level. This allows the engine 10 to operate at a higher speed.

[0057] At time T23 , the speed ratio is reduced to the rotation speed of the engine 10 when the gear ratio is shifted to a higher gear step in the stepped gear shift control, and the rotation speed of the engine 10 is increased again thereafter.

[0058] Similarly, at time T24, the automatic transmission 20 of this embodiment performs an upshift determination because the target PRI speed reaches the upshift determination speed. At this point, the lockup clutch 2a is nearing full engagement. Therefore, the actual slip speed and the resulting residual slip speed of the torque converter 2 are lower than at time T21. Therefore, the upshift determination speed is set higher than at time T21. Thus, since the upshift determination is performed when the engine 10 speed has increased compared to time T12, the upshift is executed at time T25 after the engine 10 speed has reached a sufficiently high speed. Consequently, the engine 10 can operate at a higher speed.

[0059] At time T26 , the speed ratio is reduced to the rotation speed of the engine 10 when the gear ratio is shifted to a higher gear step in the stepped gear shift control, and the rotation speed of the engine 10 is increased again thereafter.

[0060] At time T27, the automatic transmission 20 of this embodiment performs an upshift determination because the target PRI speed reaches the upshift determination speed. At this time, the lockup clutch 2a is fully engaged. Therefore, the upshift determination speed coincides with the LU upper limit PRI speed.

[0061] As described above, in the automatic transmission 20, when the lockup clutch 2a is engaged, an upshift is initiated when the rotational speed of the input shaft 2b reaches a first rotational speed. When the lockup clutch 2a is released or slipping, an upshift is initiated when the rotational speed of the input shaft 2b reaches a second rotational speed obtained by subtracting a first predetermined rotational speed from the first rotational speed. The first predetermined rotational speed is set to decrease as the output torque of the engine 10 increases. Specifically, the first predetermined rotational speed is the sum of the actual slip rotational speed of the lockup clutch 2a and the residual slip rotational speed of the lockup clutch 2a that may occur until the upshift is initiated (before the upshift is initiated).

[0062] When the output torque of engine 10 is high, the sum of the current actual slip speed and the residual slip speed of torque converter 2 that may result from this (the first predetermined speed) is set to a smaller value. Therefore, since upshifting is performed while the engine 10 speed is relatively high, the gear shift can be performed after the engine 10 speed is increased to a speed that meets the driver's acceleration request. Therefore, when the driver's acceleration request is large, upshifting can be performed while the engine 10 speed is high. Therefore, a gear shift that meets the driver's intention can be performed. Furthermore, in this case, since the difference from the maximum torque of engine 10 is small, even if the output torque of engine 10 increases before upshifting, an excessive increase in the engine 10 speed can be suppressed.

[0063] On the other hand, when the output torque of the engine 10 is low, there is a possibility that the output torque deviates from the maximum torque of the engine 10 compared to when the output torque is high. In this state, the output torque of the engine 10 increases before an upshift is performed, and there is a possibility that the speed of the engine 10 at which the upshift should be performed will be exceeded.

[0064] In contrast, in the automatic transmission 20 , when the output torque of the engine 10 is low, an upshift is performed at a correspondingly low engine 10 rotation speed. Therefore, by delaying the upshift timing, an excessive increase in the engine 10 rotation speed can be suppressed.

[0065] Furthermore, even when the lockup clutch 2a is slipping, upshifting begins when the second speed is reached, which is the first speed minus the actual slip speed and any residual slip speed that may have occurred before the upshift begins. This prevents excessive increases in the engine 10 speed and allows upshifting at high speeds while the engine 10 is running at near-maximum torque. Consequently, gear changes can be performed in accordance with the driver's intent.

[0066] In addition, the speed change mechanism 4 is a continuously variable speed change mechanism that steplessly changes the speed ratio between the input shaft 2b and the output shaft 4e. When the lock-up clutch 2a is connected, when the rotational speed of the input shaft 2b reaches the first rotational speed or the third rotational speed, an upshift is performed. When the lock-up clutch 2a is released or slipping, when the rotational speed of the input shaft 2b reaches the second rotational speed or the third rotational speed, an upshift is performed.

[0067] Thus, even when the speed change control during acceleration of the present embodiment is applied to a continuously variable transmission that performs stepped speed change control such as a stepped transmission, when the driver's acceleration request is large, upshifting can be performed while the engine 10 has a high rotational speed. Therefore, speed change that meets the driver's intention can be performed.

[0068] Next, refer to Figures 5 to 8 The following describes the delay control based on the pre-read vehicle speed in the speed change control during acceleration performed by the transmission controller 40. The delay control based on the pre-read vehicle speed is performed by the transmission controller 40 at regular intervals.

[0069] First, refer to Figures 5 to 7 , the delay control based on the pre-read vehicle speed performed by the transmission controller 40 will be described. Figure 5 This is a diagram conceptually illustrating the predicted vehicle speed. Figure 6 This is a flowchart showing the delay control based on the pre-read vehicle speed performed by the transmission controller 40 . Figure 7 This is a diagram conceptually illustrating delay control based on the pre-read vehicle speed.

[0070] like Figure 5As shown, in the automatic transmission 20, when an upshift is determined and an upshift is actually initiated, the PRI speed gradually increases and then decreases toward the target PRI speed after the upshift. Therefore, in order to prevent the engine 10 speed from overshooting and increasing excessively, the automatic transmission 20 sets the target PRI speed based on the PRI speed after a look-ahead time (first predetermined time), that is, the vehicle speed after the look-ahead time (look-ahead vehicle speed). This look-ahead time is set, for example, to 0.25 seconds.

[0071] In this case, if an upshift is initiated when the target PRI speed reaches the upshift determination speed, the upshift will begin while the PRI speed is low. Therefore, there is a possibility that the PRI speed after the look-ahead time has not reached the upshift determination speed. In other words, even when the driver's acceleration request is strong, an upshift may not be possible while the engine 10 speed is high. Therefore, the automatic transmission 20 takes the look-ahead vehicle speed into consideration and performs the following speed change control during acceleration.

[0072] exist Figure 6 In step S21, the transmission controller 40 determines whether there is an upshift determination. If it is determined in step S21 that there is an upshift determination, the process proceeds to step S22. Figure 2 If an upshift determination is made in step S16, the determination is "Yes." On the other hand, if an upshift determination is not made in step S21, the process of step S21 is repeated.

[0073] In step S22 , the transmission controller 40 detects the PRI rotation speed based on the signal from the primary rotation speed sensor 66 .

[0074] In step S23, the transmission controller 40 calculates the increased rotational speed of the primary pulley 4a from the start of the upshift to the increase during the upshift.

[0075] In step S24, the transmission controller 40 determines whether the sum of the PRI speed and the increased speed is greater than the upshift determination speed (first target speed) during the upshift determination. If it is determined in step S24 that the sum of the PRI speed and the increased speed is not greater than the upshift determination speed during the upshift determination, that is, is less than the upshift determination speed during the upshift determination, the process of steps S22 through S24 is repeated. On the other hand, if it is determined in step S24 that the sum of the PRI speed and the increased speed is greater than the upshift determination speed during the upshift determination, the process proceeds to step S17. Specifically, the transmission controller 40 performs delay control by repeating the process of step S24 until the sum of the PRI speed and the increased speed reaches the upshift determination speed during the upshift determination.

[0076] Here, refer to Figure 7 , the delay control is explained in detail.

[0077] At time T1, an upshift is determined, and the target speed ratio of the automatic transmission 20 is changed from R1 to R2. Here, when an upshift is executed at time T1, the transmission controller 40 calculates an increase in rotational speed ΔS1 during the upshift.

[0078] At time T2, the transmission controller 40 determines that the sum of the PRI speed and the increased speed ΔS2 has reached the upshift determination speed. The transmission controller 40 initiates an upshift of the automatic transmission 20 from time T1, when the upshift determination is made, to time T2, after a delay. At this time, the increased speed Sa, which is the delay between time T1 when the upshift is determined and time T2 when the upshift begins, corresponds to the predetermined speed. The increased speed ΔSa, which is the delay, is set based on the increase in the PRI speed from the time the target PRI speed reaches the upshift determination speed until the actual upshift is performed. This allows the PRI speed to be used at a level higher than the upshift determination speed. Therefore, when the driver's acceleration request is strong, an upshift can be performed at a higher engine 10 speed.

[0079] Similarly, at time T3, an upshift is determined, and the target speed ratio of the automatic transmission 20 is changed from R2 to R3. Here, when an upshift is executed at time T3, the transmission controller 40 calculates the increase in rotational speed ΔS3 during the upshift.

[0080] At time T4, the transmission controller 40 determines that the sum of the PRI speed and the increased speed ΔS4 has reached the upshift determination speed. The transmission controller 40 initiates an upshift of the automatic transmission 20 from time T3, when the upshift determination is made, to time T4, after a delay. At this time, the increased speed Sb, which is the delay between time T3, when the upshift is determined, and time T4, when the upshift begins, corresponds to the predetermined speed. The increased speed ΔSb, which is the delay, is also set based on the PRI speed increase from the time the target PRI speed reaches the upshift determination speed until the upshift is actually performed. This allows the PRI speed to be used at a level higher than the upshift determination speed. Therefore, when the driver's acceleration request is strong, an upshift can be performed at a higher engine 10 speed.

[0081] return Figure 6 In step S17, the transmission controller 40 performs an upshift of the automatic transmission 20. Specifically, when the PRI speed reaches the second speed, the transmission controller 40 performs an upshift until the PRI speed reaches a speed corresponding to a higher gear step (second target speed).

[0082] Next, refer to Figure 8 , the speed change control during acceleration performed by the transmission controller 40 will be described in detail. Figure 8 It means Figure 4A timing diagram showing a case where delay control based on the pre-read vehicle speed is further applied to the speed change control during acceleration.

[0083] exist Figure 8 In the figure, the horizontal axis is time [sec], and the vertical axis represents the accelerator pedal opening APO, the predicted vehicle speed (dashed line) [km / h], the actual vehicle speed (solid line) [km / h], the target primary pulley speed (target PRI speed: dashed line) [rpm], the engine speed (solid line) [rpm], the primary speed (PRI speed: thin solid line) [rpm], the engine speed of the comparison example (thin dashed line) [rpm], the target speed ratio (dashed line), and the actual speed ratio (solid line).

[0084] The PRI speed of the comparative example is not subject to delay control based on the pre-read vehicle speed. Figure 4 The speed of the engine 10 is shown.

[0085] At time T31, since the target PRI speed reaches the upshift determination speed, the transmission controller 40 performs an upshift determination. Figure 4 The time T21 is the same as that of FIG. 2 , so the detailed description is omitted here.

[0086] In the continuously variable transmission of the comparative example, upshifting starts at time T31, and the engine 10 speed reaches its maximum value during the shift at time T32. Thereafter, the PRI speed and the engine 10 speed decrease until the gear is shifted to a higher gear.

[0087] In contrast, when delay control based on the pre-read vehicle speed is applied, upshift execution is delayed, and the engine 10 speed reaches its maximum value during the shift at time T33, which is later than time T32. At this time, the PRI speed reaches the upshift determination speed at the time of the upshift determination, and the engine 10 speed reaches the LU upper limit PRI speed.

[0088] Similarly, at time T34, the automatic transmission 20 of this embodiment performs an upshift determination because the target PRI speed reaches the upshift determination speed. The transmission controller 40 then performs an upshift determination. The upshift is then delayed, and at time T35, the engine 10 speed reaches its maximum speed during the shift. At this point, the PRI speed also reaches the upshift determination speed at the time of the upshift determination, and the engine 10 speed reaches the LU upper limit PRI speed.

[0089] At time T36, the target PRI speed reaches the upshift determination speed, so the transmission controller 40 performs an upshift determination. The upshift is then delayed, and at time T37, the engine 10 speed reaches its maximum speed during the shift. At this point, the PRI speed also reaches the upshift determination speed at the time of the upshift determination, and the engine 10 speed reaches the LU upper limit PRI speed.

[0090] As described above, when the target PRI speed set based on the vehicle speed reached after the pre-read time (first prescribed time) becomes the upshift determination speed (first target speed), the automatic transmission 20 determines to upshift until the PRI speed becomes a speed equivalent to one gear step higher (second target speed), and after the target PRI speed reaches the upshift determination speed (first target speed), upshifting is started after the PRI speed increases by only the delayed increase speed (prescribed speed).

[0091] Thus, after determining that the target PRI speed has reached the upshift determination speed and upshifting to the second target speed, upshifting is initiated after the PRI speed further increases. Therefore, when the driver's acceleration request is large, upshifting can be performed while the engine 10 speed is high. Consequently, gear changes that meet the driver's intent can be performed.

[0092] The delayed increase speed is set based on the PRI speed of the primary pulley 4a (input shaft 4d) that increases from the time when the target PRI speed reaches the upshift determination speed until the upshift is actually performed.

[0093] Thus, even if the rotation speed of the engine 10 is set high when starting an upshift, the rotation speed of the engine 10 can be prevented from becoming excessively high.

[0094] In addition, in the above embodiment, when the target PRI speed set based on the vehicle speed reached after the first specified time reaches the first target speed, it is determined that an upshift is to be performed to the second target speed. After the PRI speed reaches the upshift determination speed, the speed is increased by only the delay amount and the upshift is started.

[0095] Alternatively, upshifting may be initiated after a second predetermined time has elapsed after the PRI speed reaches the upshift determination speed. The second predetermined time is set based on the PRI speed of the primary pulley 4a (input shaft 4d) that increases from the time the target PRI speed reaches the upshift determination speed until the upshift is actually performed.

[0096] In this case as well, after the PRI speed reaches the upshift determination speed and an upshift to the second target speed is determined, the upshift is initiated after the PRI speed further increases. Therefore, when the driver's acceleration request is large, an upshift can be performed while the engine 10 speed is high. Consequently, a gear shift that meets the driver's intention can be performed.

[0097] The structure and effects of the above-mentioned embodiment will be summarized and described.

[0098] (1)(4) The automatic transmission 20 comprises: a torque converter 2, which is arranged downstream of the engine 10 in the power transmission path and has a lockup clutch 2a; a speed change mechanism 4, which is arranged downstream of the torque converter 2 and changes the speed ratio between the input shaft 2b and the output shaft 4e. The automatic transmission 20 starts to shift up when the rotation speed of the input shaft 2b reaches a first rotation speed when the lockup clutch 2a is connected, and starts to shift up when the rotation speed of the input shaft 2b reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed when the lockup clutch 2a is released or slipping. The first predetermined rotation speed decreases as the output torque of the engine 10 increases.

[0099] In this configuration, when the output torque of engine 10 is high, the first predetermined speed is low. Therefore, since an upshift is performed while the engine 10 speed is relatively high, the gear shift can be performed after the engine 10 speed is increased to a speed that meets the driver's acceleration request. Therefore, when the driver's acceleration request is large, an upshift can be performed while the engine 10 speed is high. Therefore, a gear shift that meets the driver's intention can be performed. Furthermore, in this case, since the difference from the maximum torque of engine 10 is small, even if the output torque of engine 10 increases before the upshift, an excessive increase in the engine 10 speed can be suppressed.

[0100] On the other hand, when the output torque of engine 10 is low, there is a possibility that the maximum torque of engine 10 will deviate from that when the output torque is high. In this situation, the output torque of engine 10 increases before an upshift, potentially exceeding the speed of engine 10 required for the upshift. In contrast, when the output torque of engine 10 is low, automatic transmission 20 performs an upshift at a correspondingly low speed of engine 10. Therefore, by delaying the timing of the upshift, an excessive increase in the speed of engine 10 can be suppressed.

[0101] (2) The first predetermined rotational speed is the sum of the actual slip rotational speed of the lockup clutch 2a and the residual slip rotational speed of the lockup clutch 2a that may occur until the start of the upshift.

[0102] In this configuration, even when the lockup clutch 2a is slipping, an upshift begins when the second speed is reached, which is the first speed minus the actual slip speed and any residual slip speed that may have occurred before the upshift begins. This prevents excessive increases in engine 10 speed and allows upshifts at high speeds while the engine 10 is running near maximum torque. This allows for gear changes that suit the driver's intent.

[0103] (3) The speed change mechanism 4 is a continuously variable speed change mechanism that steplessly changes the speed ratio between the input shaft 2b and the output shaft 4e. When the lockup clutch 2a is engaged, an upshift is performed when the rotational speed of the input shaft 2b reaches the first rotational speed or reaches the third rotational speed. When the lockup clutch 2a is released or slipping, an upshift is performed when the rotational speed of the input shaft 2b reaches the second rotational speed or reaches the third rotational speed.

[0104] According to this configuration, even when applied to a continuously variable transmission that performs step-by-step speed control, such as a stepped transmission, when the driver's acceleration request is large, upshifting can be performed while the engine 10 has a high speed.

[0105] While the embodiment of the present invention has been described above, the above embodiment merely illustrates one application example of the present invention, and the technical scope of the present invention is not limited to the specific configuration of the above embodiment.

[0106] For example, in the above embodiment, the automatic transmission 20 is described as a continuously variable transmission that performs step-by-step speed control, such as a stepped transmission. However, the automatic transmission 20 may be a continuously variable transmission that does not perform step-by-step speed control, or an automatic transmission that includes a stepped speed change mechanism. Furthermore, in a continuously variable transmission in which the driver can manually shift in steps, the transmission controller 40 automatically performs an upshift when the driver increases the engine 10 speed without performing an upshift operation.

[0107] As various programs executed by the transmission controller 40 , programs stored in a non-transitory recording medium such as a CD-ROM can be used.

[0108] Explanation of symbols

[0109] 20: Automatic transmission

[0110] 2: Torque converter

[0111] 2a: Lock-up clutch

[0112] 2b: Input shaft

[0113] 4: Speed ​​change mechanism (speed change mechanism, continuously variable speed change mechanism)

[0114] 4e: Output shaft

[0115] 10: Engine (drive source)

Claims

1. An automatic transmission comprising: a torque converter disposed downstream of a drive source in a power transmission path and having a lockup clutch; and a speed change mechanism disposed downstream of the torque converter and configured to change a speed ratio between an input shaft and an output shaft, wherein: When the rotation speed of the input shaft reaches a first rotation speed in the state where the lock-up clutch is engaged, an upshift is started. When the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed in a state where the lockup clutch is released or slipping, an upshift is started. The first predetermined rotation speed decreases as the output torque of the driving source increases.

2. The automatic transmission according to claim 1, wherein: The first predetermined rotational speed is the sum of the actual slip rotational speed of the lockup clutch and the residual slip rotational speed of the lockup clutch that may occur until the start of an upshift.

3. The automatic transmission according to claim 1 or 2, wherein: The speed change mechanism is a continuously variable speed change mechanism that changes the speed ratio between the input shaft and the output shaft steplessly. When the rotation speed of the input shaft reaches the first rotation speed or the third rotation speed in the state where the lock-up clutch is engaged, an upshift is performed. When the rotation speed of the input shaft reaches the second rotation speed or reaches the third rotation speed in a state where the lock-up clutch is released or slipping, an upshift is performed.

4. A control method for an automatic transmission comprising: a torque converter disposed downstream of a drive source in a power transmission path and having a lockup clutch; and a speed change mechanism disposed downstream of the torque converter and configured to change a speed ratio between an input shaft and an output shaft, wherein: When the rotation speed of the input shaft reaches a first rotation speed in the state where the lock-up clutch is engaged, an upshift is started. When the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed in a state where the lockup clutch is released or slipping, an upshift is started. The first predetermined rotation speed decreases as the output torque of the driving source increases.

5. A storage medium storing a program executable by a computer of an automatic transmission, the automatic transmission comprising: a torque converter disposed downstream of a drive source in a power transmission path and having a lockup clutch; and a speed change mechanism disposed downstream of the torque converter and configured to change a speed ratio between an input shaft and an output shaft. in, The program causes the computer to execute the following steps: When the rotation speed of the input shaft reaches a first rotation speed in the state where the lock-up clutch is engaged, an upshift is started. When the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed in a state where the lockup clutch is released or slipping, an upshift is started. The first predetermined rotation speed decreases as the output torque of the driving source increases.

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