JP7202455B2 - AUTOMATIC TRANSMISSION AND AUTOMATIC TRANSMISSION CONTROL METHOD - Google Patents

Description

The present invention relates to an automatic transmission and a control method for the automatic transmission.

In JP2016-48100A, when it is determined that the lockup clutch of the torque converter is in the engaged state and the running state of the vehicle is in a state in which vibration may occur, the lockup clutch is put in the slip engagement state to suppress the vibration. A control device for an automatic transmission that prevents the generation of noise due to

In the control device for an automatic transmission disclosed in JP2016-48100A, the engagement pressure (engagement pressure) of the lockup clutch is gradually lowered to place the lockup clutch in the first slip engagement state, and then the engagement pressure (engagement pressure) is reduced. The combined pressure) is gradually increased to shift the lockup clutch to a second slip engagement state in which the amount of slip is smaller than that in the first slip engagement state.

However, in the control device for an automatic transmission disclosed in JP2016-48100A, when shifting from the first slip engagement state to the second slip engagement state, the delay in the response of the valve, etc. causes the lock-up clutch to be disengaged. If the amount of slip becomes too large, there is a risk that the engine will rev up. In this way, when the engine revs up, the driver may feel uncomfortable and the fuel efficiency may deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of such a technical problem, and an object of the present invention is to suppress engine racing when slip control is performed on a lockup clutch of a torque converter.

According to one aspect of the present invention, an automatic transmission includes a transmission mechanism, a torque converter provided on a power transmission path between an engine and the transmission mechanism, and a torque converter having a lockup clutch. 1 Smooth-off control that gradually lowers the engagement pressure of the lockup clutch when the torque reaches a predetermined torque or more, and gradually increases the engagement pressure of the lockup clutch after execution of the smooth-off control so that the lockup clutch slips to a predetermined level. and a control device for executing drive slip control to set the state, wherein the control device controls the difference between the rotational speed on the input shaft side of the torque converter and the rotational speed on the output shaft side of the torque converter to a first predetermined value. In the above cases, the instruction pressure for engaging the lockup clutch is increased stepwise by the first predetermined amount, and the smooth-off control is shifted to the drive slip control.

According to this aspect, it is possible to suppress engine racing when slip control is performed on the lockup clutch of the torque converter.

FIG. 1 is a schematic configuration diagram of a vehicle according to an embodiment of the invention. FIG. 2 is a flow chart showing the flow of slip control according to the embodiment of the present invention. FIG. 3 is a flow chart showing the flow of slip control according to the embodiment of the present invention. FIG. 4 is a map showing slip start conditions according to the embodiment of the present invention. FIG. 5 is a map showing the relationship between the predetermined value D1 and the amount of change in the turbine rotation speed Ntout according to the embodiment of the invention. FIG. 6 is a timing chart of slip control according to the embodiment of the present invention. FIG. 7 is a timing chart of slip control according to the embodiment of the present invention. FIG. 8 is a timing chart of slip control according to the embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a vehicle 100. As shown in FIG. A vehicle 100 includes an engine 1, an automatic transmission 3, an oil pump 5, drive wheels 6, and a controller 10 as a control device.

The engine 1 is an internal combustion engine that uses gasoline, light oil, or the like as fuel, and functions as a drive source for running. The rotation speed, torque, etc. of the engine 1 are controlled based on commands from the controller 10 .

The automatic transmission 3 includes a torque converter 2, an engagement element 31, a variator 30 as a transmission mechanism, a hydraulic control valve unit 40 (hereinafter also simply referred to as "valve unit 40"), and oil (working oil). and an oil pan 32 that stores the

Torque converter 2 is provided on a power transmission path between engine 1 and driving wheels 6 . The torque converter 2 transmits power through fluid. Further, the torque converter 2 can increase the power transmission efficiency of the driving force from the engine 1 by engaging the lockup clutch 2a.

The engagement element 31 is arranged on the power transmission path between the torque converter 2 and the variator 30 . The fastening element 31 comprises a forward clutch and a reverse brake (not shown). The engagement element 31 is controlled by oil pressure-regulated by a valve unit 40 based on a command from the controller 10 using the discharge pressure of the oil pump 5 as a source pressure. As the engaging element 31, for example, a wet multi-plate clutch is used.

The variator 30 is arranged on the power transmission path between the engaging element 31 and the drive wheels 6, and changes the gear ratio steplessly according to the vehicle speed, accelerator opening, and the like. The variator 30 includes a primary pulley 30a, a secondary pulley 30b, and a belt 30c wound around both pulleys 30a and 30b. The pulley pressure moves the movable pulley of the primary pulley 30a and the movable pulley of the secondary pulley 30b in the axial direction to change the pulley contact radius of the belt 30c, thereby changing the gear ratio steplessly. The pulley pressure acting on the primary pulley 30a and the pulley pressure acting on the secondary pulley 30b are adjusted by the valve unit 40 using the discharge pressure from the oil pump 5 as the source pressure.

The differential 12 is connected to the output shaft of the secondary pulley 30b of the variator 30 via a final reduction gear mechanism (not shown). A drive wheel 6 is connected to the differential 12 via a drive shaft 13 .

The oil pump 5 is driven by transmission of rotation of the engine 1 via a belt. The oil pump 5 is configured by, for example, a vane pump. The oil pump 5 sucks up oil stored in the oil pan 32 and supplies the oil to the valve unit 40 . The oil supplied to the valve unit 40 is used for driving the lockup clutch 2a, driving the pulleys 30a and 30b, driving the engaging element 31, lubricating each element of the automatic transmission 3, and the like.

The controller 10 is composed of a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM) and an input/output interface (I/O interface). The controller 10 is composed of a plurality of microcomputers. Specifically, the controller 10 includes an ATCU that controls the automatic transmission 3, an SCU that controls the shift range, an ECU that controls the engine 1, and the like.

The controller 10 includes a first rotational speed sensor 51 for detecting the rotational speed Ne of the engine 1, a second rotational speed sensor 52 for detecting the rotational speed of the turbine on the output shaft side of the torque converter 2 (turbine rotational speed Ntout), A third rotation speed sensor 53 that detects the output rotation speed Nout of the engagement element 31 (=the rotation speed of the primary pulley 30a), a fourth rotation speed sensor 54 that detects the rotation speed of the secondary pulley 30b, and a vehicle speed sensor that detects the vehicle speed V. 55, an inhibitor switch 56 that detects the select range of the engagement element 31 (the state of the select lever or select switch that switches between forward, reverse, neutral and parking), an accelerator opening sensor 57 that detects the accelerator opening AP, and a brake pedal force Signals from a pedal force sensor 58 for detection, a torque sensor 59 for detecting the output torque τ of the engine 1, and the like are input. The controller 10 controls various operations of the engine 1 and the automatic transmission 3 based on these input signals.

By the way, when the output torque τ of the engine 1 is in a predetermined range with the lockup clutch 2a fully engaged, vibration may occur in the power transmission path. For this reason, when the output torque τ is within a region where vibration can occur, the torque converter 2 absorbs this vibration by causing the lockup clutch 2a to slip.

In such slip control for slipping the lockup clutch 2a, first, the engagement pressure Pc of the lockup clutch 2a is gradually reduced. When it is detected that the lockup clutch 2a has slipped to some extent, the engagement pressure Pc of the lockup clutch 2a is gradually increased, and control is performed so that the slip amount reaches the target value.

However, in such slip control, when the control is switched so as to increase the engagement pressure Pc of the lockup clutch 2a from a decreased state, the engagement pressure Pc is not immediately supplied due to a delay in the response of the valve or the like. However, the slip amount of the lockup clutch 2a may increase. If the amount of slip increases in this way, the engine 1 will rev up, which may lead to deterioration in fuel efficiency or a driver's discomfort.

Therefore, in the present embodiment, in the slip control of the lockup clutch 2a, a correction process is executed in order to prevent the engine 1 from racing. The slip control of the lockup clutch 2a in this embodiment will be specifically described below with reference to the flow charts shown in FIGS.

In step S1, it is determined whether or not a slip control start condition for the lockup clutch 2a is satisfied. Specifically, based on the map shown in FIG. 4, the controller 10 determines whether or not the output torque τ of the engine 1 detected by the torque sensor 59 has reached or exceeded a predetermined value τ1. If the output torque τ of the engine 1 is equal to or greater than the predetermined value τ1, the controller 10 determines that the slip control start condition for the lockup clutch 2a is satisfied, and proceeds to step S2. If the output torque .tau. of the engine 1 is less than the predetermined value .tau.1, the lockup clutch 2a is maintained in the complete lockup state, and the process proceeds to END. In step S1 (the map shown in FIG. 4), it is determined whether or not the slip control start condition is satisfied based only on the change in the output torque τ of the engine 1. However, the output of the engine 1 is not limited to this. In addition to changes in the torque τ, the determination may be made according to changes in the turbine rotation speed Ntout, the oil temperature, the gear ratio, and the like.

In step S2, smooth off control is executed. Smooth-off control in this embodiment is control for smoothly shifting from a state in which the lockup clutch 2a is completely engaged to a drive slip state in which power is transmitted while maintaining a predetermined slip amount. In the smooth-off control, the controller 10 controls the valve unit 40 so as to gradually decrease the engagement pressure Pc of the lockup clutch 2a of the torque converter 2. FIG.

In step S3, correction processing of the engagement pressure Pc of the lockup clutch 2a is executed. Specifically, the controller 10 corrects the indicated pressure Pt of the lockup clutch 2a during execution of the smooth-off control. Details of the correction processing will be described later.

In step S4, drive slip control is executed. Specifically, the controller 10 controls the valve unit 40 so that the lockup clutch 2a maintains a predetermined slip amount after the smooth-off control ends.

Next, the process of correcting the command pressure Pt of the lockup clutch 2a in step S3 will be described with reference to the flowchart shown in FIG.

In step S31, the output torque τ of the engine 1 is stored. Specifically, the controller 10 stores the output torque τ of the engine 1 detected by the torque sensor 59 at the start of smooth-off control. Hereinafter, the output torque stored at this time will be referred to as output torque τs.

In step S32, it is determined whether or not the torque deviation amount τd is equal to or greater than a predetermined value α1. Specifically, the controller 10 calculates the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59, and calculates the torque deviation amount τd. is greater than or equal to a predetermined value α1. If the torque deviation amount τd is equal to or greater than the predetermined value α1, the process proceeds to step S33, and if the torque deviation amount τd is less than the predetermined value α1, the process proceeds to step S38.

In step S33, the indicated pressure Pt is increased by a predetermined amount P2. Specifically, the controller 10 increases the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a by a predetermined amount P2.

In step S34, it is determined whether or not the torque deviation amount τd is equal to or greater than a predetermined value α2. Specifically, the controller 10 calculates the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59, and calculates the torque deviation amount τd. is greater than or equal to a predetermined value α2. If the torque deviation amount τd is equal to or greater than the predetermined value α2, the process proceeds to step S35, and if the torque deviation amount τd is less than the predetermined value α2, the process proceeds to step S38.

In step S35, the indicated pressure Pt is increased by a predetermined amount P3. Specifically, the controller 10 increases the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a by a predetermined amount P3.

In step S36, it is determined whether or not the torque deviation amount τd is equal to or greater than a predetermined value α3. Specifically, the controller 10 calculates the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59, and calculates the torque deviation amount τd. is greater than or equal to a predetermined value α3. If the torque deviation amount τd is equal to or greater than the predetermined value α3, the process proceeds to step S37, and if the torque deviation amount τd is less than the predetermined value α3, the process proceeds to step S38.

In step S37, the indicated pressure Pt is increased by a predetermined amount P4. Specifically, the controller 10 increases the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a by a predetermined amount P4.

As the torque deviation amount τd increases, that is, as the output torque τ increases, the slip amount of the lockup clutch 2a increases even with the same engagement pressure Pc. Therefore, when the torque deviation amount τd is large, the indicated pressure Pt is increased in advance by a predetermined amount P2, P3, P4. As a result, it is possible to prevent the engine 1 from revving up due to an increase in the amount of slip when shifting from smooth-off control to drive slip control. Note that the predetermined amounts P2, P3, and P4 may be the same value or different values.

In step S38, it is determined whether or not the differential rotation D is greater than or equal to a predetermined value D1. Specifically, the controller 10 detects the rotational speed Ne of the engine 1 detected by the first rotational speed sensor 51 and the rotational speed Ntout of the output shaft of the torque converter 2 detected by the second rotational speed sensor 52. A rotational speed difference D, which is the absolute value of the difference in rotational speed, is calculated, and it is determined whether or not the rotational speed difference D is greater than or equal to a predetermined value D1. The rotation speed Ne of the engine 1 corresponds to the rotation speed Ntin of the torque converter 2 on the input shaft side.

In this embodiment, the predetermined value D1 changes according to the amount of change in the turbine rotational speed Ntout, as shown in the map shown in FIG. The amount of change in turbine rotational speed Ntout is a value corresponding to the rotational acceleration of the output shaft of torque converter 2 . Note that the predetermined value D1 may be a constant value.

If the differential rotation D is greater than or equal to the predetermined value D1, the process proceeds to step S39, and if the differential rotation D is less than the predetermined value D1, the process returns to step S32.

In step S39, it is determined whether or not the foot return determination condition is satisfied. Specifically, the controller 10 determines from the accelerator opening AP detected by the accelerator opening sensor 57 whether or not the accelerator pedal is released during the smooth off control. More specifically, the controller 10 calculates the speed Vap of the accelerator pedal from the accelerator opening AP detected by the accelerator opening sensor 57, and determines whether the accelerator opening AP decreases at a predetermined speed V1 or more. judge. If the accelerator opening AP decreases at a predetermined speed V1 or higher, it is determined that the foot return determination condition is satisfied, and the process proceeds to step S40. If the accelerator opening AP does not decrease at a predetermined speed V1 or more, it is determined that the foot return determination condition is not established, and the process proceeds to END.

In step S40, the indicated pressure Pt is increased by a predetermined amount P1. Specifically, the controller 10 increases the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a by a predetermined amount P1 in a stepwise manner.

Next, changes in the command pressure Pt in the slip control of the lockup clutch 2a in this embodiment will be described with reference to the time charts shown in FIGS. 6 to 8. FIG.

First, referring to FIG. 6, the case where the accelerator pedal is slightly further depressed will be described.

At time t1, when the accelerator pedal is further depressed, the output torque τ of the engine 1 increases.

At time t2, when the output torque τ of the engine 1 reaches or exceeds a predetermined value τ1, the controller 10 executes smooth-off control. Specifically, the controller 10 gradually decreases the command pressure Pt of the lockup clutch 2a. The controller 10 also stores the output torque τs of the engine 1 at time t2 detected by the torque sensor 59 .

Further, when the smooth-off control is started at time t2, the controller 10 calculates the accelerator pedal speed Vap from the accelerator opening AP detected by the accelerator opening sensor 57. FIG.

When the engagement pressure Pc of the lockup clutch 2a decreases, the lockup clutch 2a slips (time t3). When the engagement pressure Pc of the lockup clutch 2a further decreases, the difference between the rotation speed Ntin on the input shaft side of the torque converter 2 and the rotation speed Ntout on the output shaft side of the torque converter 2 reaches a predetermined value D1 (time t4). . When the difference (differential rotation D) between the rotation speed Ntin on the input shaft side of the torque converter 2 and the rotation speed Ntout on the output shaft side of the torque converter 2 reaches a predetermined value D1, the controller 10 performs slip control of the lockup clutch 2a. from smooth-off control to drive slip control. At this time, the controller 10 increases the command pressure Pt of the lockup clutch 2a by a predetermined amount P1 in a stepwise manner. After that, the controller 10 controls the valve unit 40 to gradually increase the engagement pressure Pc of the lockup clutch 2a.

At time t5, when the differential rotation D reaches the target rotational speed difference (differential rotation Dt), the controller 10 controls the valve unit 40 so that the differential rotation D maintains the differential rotation Dt.

The dotted lines for the command pressure Pt and the rotational speed shown in FIG. It shows the characteristics of the velocity Ne. In this case, as is clear from FIG. 6, the rotation speed Ne of the engine 1 increases greatly.

Therefore, as in the present embodiment, when the smooth-off control is shifted to the drive slip control (at time t4), the command pressure Pt is increased stepwise to quickly increase the engagement pressure Pc of the lockup clutch 2a. It is possible to prevent the engine 1 from racing by suppressing an increase in the slip amount.

Next, referring to FIG. 7, the case where the accelerator pedal is further depressed will be described.

At time t11, when the accelerator pedal is further depressed, the output torque τ of the engine 1 increases.

At time t12, when the output torque τ of the engine 1 reaches or exceeds a predetermined value τ1, the controller 10 executes smooth-off control. Specifically, the controller 10 gradually decreases the command pressure Pt of the lockup clutch 2a. The controller 10 also stores the output torque τs of the engine 1 at time t12 detected by the torque sensor 59 .

The output torque t of the engine 1 increases, and at time t13, the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59 becomes a predetermined value. When α1 or more is reached, the controller 10 increases the command pressure Pt of the lockup clutch 2a by a predetermined amount P2.

The output torque t of the engine 1 further increases, and at time t14, the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59 reaches a predetermined value. When the value α2 or more is reached, the controller 10 further increases the command pressure Pt of the lockup clutch 2a by a predetermined amount P3.

By the way, when the accelerator pedal is further depressed, the amount of change in the turbine rotation speed Ntout (rotational acceleration of the output shaft of the torque converter 2) increases. At this time, noise is likely to occur in the sensor that detects the turbine rotation speed Ntout, the differential rotation D increases, and there is a possibility that an erroneous determination may occur. Therefore, in this embodiment, as described above, the predetermined value D1 is changed according to the amount of change in the turbine rotation speed Ntout (see FIG. 5). As a result, even if the differential rotation D increases due to noise when the amount of change in the turbine rotation speed Ntout is large, the predetermined value D1 increases, so that erroneous determination can be prevented.

When the engagement pressure Pc of the lockup clutch 2a decreases, the lockup clutch 2a slips (time t15). When the engagement pressure Pc of the lockup clutch 2a further decreases, the difference (differential rotation D) between the rotation speed Ntin on the input shaft side of the torque converter 2 and the rotation speed Ntout on the output shaft side of the torque converter 2 reaches a predetermined value D1. becomes (time t16). When the differential rotation D reaches a predetermined value D1, the controller 10 shifts the slip control of the lockup clutch 2a from smooth off control to drive slip control. At this time, the controller 10 increases the command pressure Pt of the lockup clutch 2a by a predetermined amount P1 in a stepwise manner. After that, the controller 10 controls the valve unit 40 to gradually increase the engagement pressure Pc of the lockup clutch 2a.

At time t17, when the differential rotation D reaches the target rotation speed difference (differential rotation Dt), the controller 10 controls the valve unit 40 so that the differential rotation D maintains the differential rotation Dt.

Note that the dotted lines for the command pressure Pt and the rotation speed shown in FIG. The characteristics of the rotation speed Ne, and the characteristics of the command pressure Pt and the engine speed Ne when the command pressure Pt is not increased stepwise when shifting from smooth-off control to drive slip control (time t16) are shown.

If the degree of increase in the output torque τ of the engine 1 is large, the lockup clutch 2a will unintentionally begin to slip while the command pressure Pt is decreasing, and the engine 1 will rev up as indicated by the dotted line in FIG. There is a risk of

Therefore, in the present embodiment, the command pressure Pt is increased when the torque deviation amount τd becomes equal to or greater than a predetermined value (predetermined values α1, α2). This prevents the lockup clutch 2a from slipping unintentionally.

Further, when the torque deviation amount τd increases, that is, when the output torque τ increases, the slip amount of the lockup clutch 2a increases even with the same engagement pressure Pc. In this embodiment, the command pressure Pt is increased when the torque deviation amount τd becomes equal to or greater than a predetermined value (predetermined values α1, α2). is increased and the engine 1 can be prevented from racing up.

Further, in the present embodiment, when the smooth-off control is shifted to the drive slip control (time t16), the indicated pressure Pt is increased in a stepwise manner, thereby rapidly increasing the engagement pressure Pc of the lockup clutch 2a and slipping. By suppressing the increase in the amount, it is possible to prevent the engine 1 from racing.

Further, in the present embodiment, when the accelerator pedal is strongly depressed and the amount of change in the turbine rotation speed Ntout increases, the predetermined value D1 is increased. can be done accurately.

Next, with reference to FIG. 8, the case where the accelerator pedal is further depressed and then released (the foot is returned) will be described.

At time t21, when the accelerator pedal is further depressed, the output torque τ of the engine 1 increases.

At time t22, when the output torque τ of the engine 1 reaches or exceeds a predetermined value τ1, the controller 10 executes smooth-off control. Specifically, the controller 10 gradually decreases the command pressure Pt of the lockup clutch 2a. The controller 10 also stores the output torque τ (output torque τs) of the engine 1 at time t22 detected by the torque sensor 59 .

The output torque t of the engine 1 increases, and at time t23, the difference (torque deviation amount τd) between the stored output torque τs and the current output torque τr of the engine 1 detected by the torque sensor 59 becomes a predetermined value. When α1 or more is reached, the controller 10 increases the command pressure Pt of the lockup clutch 2a by a predetermined amount P2.

At time t24, when the accelerator pedal is released and the accelerator opening AP decreases at a predetermined speed V1 or higher, the controller 10 determines that the foot return determination condition is satisfied.

When the engagement pressure Pc of the lockup clutch 2a decreases, the lockup clutch 2a slips (time t25). When the engagement pressure Pc of the lockup clutch 2a further decreases, the difference (differential rotation D) between the rotation speed Ntin on the input shaft side of the torque converter 2 and the rotation speed Ntout on the output shaft side of the torque converter 2 reaches a predetermined value D1. becomes (time t26). When the differential rotation D reaches a predetermined value D1, the controller 10 shifts the slip control of the lockup clutch 2a from smooth off control to drive slip control.

At this time, since the controller 10 determines that the foot return determination condition is satisfied at time t24, the command pressure Pt of the lockup clutch 2a is not stepped up by the predetermined amount P1, and the drive is started from the smooth off control. Shift to slip control. The controller 10 then controls the valve unit 40 to gradually increase the engagement pressure Pc of the lockup clutch 2a.

At time t27, when the differential rotation D reaches the target rotation speed difference (differential rotation Dt), the controller 10 controls the valve unit 40 so that the differential rotation D maintains the differential rotation Dt.

If the accelerator opening AP decreases at a predetermined speed V1 or higher, the output torque τ decreases. Therefore, if the indicated pressure Pt is increased stepwise by a predetermined amount P1 in the same manner as when the output torque τ is increased, a shock may occur. Therefore, in the present embodiment, when the accelerator opening AP is decreasing at a predetermined speed V1 or more, the command pressure Pt of the lockup clutch 2a is not increased by a predetermined amount P1 in a stepwise manner, and the smooth-off control is stopped. Shift to drive slip control. As a result, it is possible to suppress the occurrence of a shock at the time of transition from smooth-off control to drive-slip control.

The configuration, action, and effect of the embodiment of the present invention configured as described above will be collectively described.

The automatic transmission 3 is provided on a power transmission path between the transmission mechanism (variator 30) and the engine 1 and the transmission mechanism (variator 30), the torque converter 2 having the lockup clutch 2a, and the output of the engine 1 When the torque τ becomes equal to or greater than a first predetermined torque (predetermined value τ1), a smooth-off control for gradually reducing the engagement pressure Pc of the lockup clutch 2a, and the engagement pressure Pc of the lockup clutch 2a after execution of the smooth-off control. and a drive slip control that gradually raises the lockup clutch 2a to a predetermined slip state. side rotation speed Ntin and the output shaft side rotation speed Ntout of the torque converter 2 (differential rotation D) becomes equal to or greater than a first predetermined value (predetermined value D1), the engagement pressure of the lockup clutch 2a is increased. The instructed pressure Pt of Pc is stepwise increased by a first predetermined amount (predetermined amount P1) to shift from smooth-off control to drive slip control.

When the smooth-off control is shifted to the drive slip control, the command pressure Pt of the engagement pressure Pc of the lockup clutch 2a is increased stepwise by a first predetermined amount (predetermined amount P1), thereby delaying the supply of hydraulic pressure. can be suppressed. As a result, racing of the engine 1 can be suppressed when slip control is performed on the lockup clutch 2 a of the torque converter 2 .

In the automatic transmission 3, the control device (controller 10) changes the first predetermined amount (predetermined amount P1) according to the oil temperature.

When the oil temperature is low, the response tends to be delayed due to the high viscosity of the oil. Therefore, when the oil temperature is low, the response delay can be suppressed by increasing the first predetermined amount (predetermined amount P1). Therefore, the control can be stabilized by changing the first predetermined amount (predetermined amount P1) according to the oil temperature.

In the automatic transmission 3, the control device (controller 10) changes the first predetermined value (predetermined value D1) according to the amount of change in the rotation speed Ntout on the output shaft side.

For example, when the amount of depression of the accelerator pedal is large, the amount of change in rotational speed Ntout on the output shaft side becomes large. At this time, noise is likely to occur in the sensor that detects the rotation speed Ntout on the output shaft side, and there is a possibility that an erroneous determination will occur. Therefore, erroneous determination can be prevented by changing the first predetermined value (predetermined value D1) according to the amount of change in the rotation speed Ntout on the output shaft side.

In the automatic transmission 3, the control device (controller 10) controls the difference (torque When the deviation amount τd) becomes equal to or greater than a second predetermined value (predetermined value α1), the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a is increased by a second predetermined amount (predetermined amount P2).

If the degree of increase in the output torque τ of the engine 1 is large, the lockup clutch 2a may unintentionally begin to slip while the command pressure Pt is decreasing, and the engine 1 may rev up. Therefore, in the present embodiment, the command pressure Pt is increased when the torque deviation amount τd becomes equal to or greater than the second predetermined value (predetermined value α1). This prevents the lockup clutch 2a from slipping unintentionally.

Further, when the torque deviation amount τd increases, that is, when the output torque τ increases, the slip amount of the lockup clutch 2a increases even with the same engagement pressure Pc. Therefore, when the torque deviation amount τd is large, the command pressure Pt of the engagement pressure Pc of the lockup clutch 2a is increased in advance by a second predetermined amount (predetermined amount P2), thereby shifting from smooth-off control to drive slip control. When doing so, it is possible to prevent the engine 1 from revving up due to an increase in the amount of slip.

In the automatic transmission 3, the control device (controller 10) controls the difference between the rotational speed Ntin on the input shaft side and the rotational speed Ntout on the output shaft side ( When the differential speed D) becomes equal to or greater than a first predetermined value (predetermined value D1), the indicated pressure Pt of the engagement pressure Pc of the lockup clutch 2a is increased stepwise by a first predetermined amount (predetermined amount P1). smooth-off control to drive slip control.

If the accelerator opening AP decreases at a predetermined speed V1 or higher, the output torque τ decreases. Therefore, if the indicated pressure Pt is increased stepwise by the first predetermined amount (predetermined amount P1) as in the case where the output torque τ is increased, a shock may occur. Therefore, when the accelerator opening AP is decreasing at a predetermined speed V1 or more, the instruction pressure Pt of the engagement pressure Pc of the lockup clutch 2a is increased stepwise by a first predetermined amount (predetermined amount P1). Smooth-off control is shifted to drive slip control. As a result, it is possible to suppress the occurrence of a shock during slip control.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. is not.

The above slip control can also be applied to a CVT with an auxiliary transmission and a stepped transmission.

In the above embodiment, the command pressure Pt is increased in three stages (predetermined amounts P2, P3, P4) according to the torque deviation amount τd, but the present invention is not limited to this, and may be increased in one stage, two stages, or four or more stages. There may be. Further, when the indicated pressure is increased by the predetermined amounts P2, P3, P4, it may be increased stepwise.

This application claims priority based on Japanese Patent Application No. 2019-82271 filed with the Japan Patent Office on April 23, 2019, and the entire contents of this application are incorporated herein by reference.

Claims (5)

a transmission mechanism;
a torque converter provided on a power transmission path between the engine and the transmission mechanism and having a lockup clutch;
smooth-off control for gradually reducing the engagement pressure of the lock-up clutch when the output torque of the engine reaches a first predetermined torque or more; and gradually reducing the engagement pressure of the lock-up clutch after execution of the smooth-off control. a drive slip control that raises the lockup clutch to a predetermined slip state, and a control device that executes
The control device is
During the smooth-off control, when the difference between the rotation speed of the input shaft of the torque converter and the rotation speed of the output shaft of the torque converter becomes equal to or greater than a first predetermined value, the engagement pressure of the lockup clutch is stepwise increased by a first predetermined amount to shift from the smooth-off control to the drive slip control, and the first predetermined value is changed according to the amount of change in the rotational speed of the output shaft. transmission. In the automatic transmission according to claim 1,
The control device is
An automatic transmission that changes the first predetermined amount according to oil temperature. The automatic transmission according to claim 1 or 2,
The control device is
During execution of the smooth-off control, if the difference between the current output torque of the engine and the output torque of the engine at the time when the smooth-off control is started becomes equal to or greater than a second predetermined value, the lock-up An automatic transmission for increasing a command pressure of a clutch engagement pressure by a second predetermined amount. In the automatic transmission according to any one of claims 1 to 3,
The control device is
When the accelerator opening decreases at a predetermined speed or more, the lockup is performed when the difference between the rotational speed of the input shaft and the rotational speed of the output shaft becomes equal to or greater than the first predetermined value. An automatic transmission that shifts from the smooth-off control to the drive-slip control without stepwise increasing the indicated pressure of the engagement pressure of the clutch by the first predetermined amount. a transmission mechanism;
a torque converter provided on a power transmission path between the engine and the transmission mechanism and having a lockup clutch;
smooth-off control for gradually reducing the engagement pressure of the lock-up clutch when the output torque of the engine reaches a first predetermined torque or more; and gradually reducing the engagement pressure of the lock-up clutch after execution of the smooth-off control. A control method for an automatic transmission that controls an automatic transmission comprising: a drive slip control that raises the lockup clutch to a predetermined slip state;
During the smooth-off control, when the difference between the rotation speed of the input shaft of the torque converter and the rotation speed of the output shaft of the torque converter becomes equal to or greater than a first predetermined value, the engagement pressure of the lockup clutch is stepwise increased by a first predetermined amount to shift from the smooth-off control to the drive slip control, and the first predetermined value is changed according to the amount of change in the rotational speed of the output shaft. Transmission control method.

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