JP5569449B2 - Automatic transmission and lockup clutch engagement method - Google Patents

Description

  The present invention relates to an automatic transmission apparatus and a lockup clutch engagement method.

  Conventionally, as this type of automatic transmission, in an in-vehicle device including a torque converter having a lock-up clutch, when the vehicle is in an accelerator-off coast state, the torque converter has an input shaft speed and an output shaft speed. There has been proposed one that engages a lock-up clutch when the rotational speed difference becomes equal to or less than a predetermined rotational speed (see, for example, Patent Document 1). In this device, the lockup clutch is locked up even in the coast state, thereby improving the transmission efficiency in the coast state.

JP-A-11-236966

  Many of the lock-up clutches have a characteristic that the engagement force of the clutch suddenly increases when torque starts to be generated in the clutch due to the action of hydraulic pressure. It depends on the gear position. For this reason, if the lockup clutch is engaged when the difference in rotational speed between the input shaft rotational speed and the output shaft rotational speed of the torque converter is equal to or lower than a predetermined rotational speed, a shock may occur depending on the gear position.

  An automatic transmission device and a lockup clutch engagement method according to the present invention are mainly intended to suppress a shock that may occur when the lockup clutch is locked up.

  In order to achieve the above-mentioned main object, the automatic transmission device and the lockup clutch engagement method of the present invention employ the following means.

The automatic transmission of the present invention is
An on-vehicle automatic transmission comprising a fluid transmission device having a lock-up clutch and a stepped automatic transmission,
An accelerator off acquisition means for acquiring the accelerator off;
A rotational speed difference acquisition means for acquiring a rotational speed difference between two rotational elements engaged and disengaged by the lock-up clutch;
When the condition for engaging the lockup clutch is established in a state where the accelerator-off is acquired, the acquired rotational speed difference is equal to or less than an engagement threshold predetermined according to the shift stage of the automatic transmission. Control means for starting engagement control for engaging the lock-up clutch at the time of,
It is a summary to provide.

  In the automatic transmission device according to the present invention, when the condition for engaging the lockup clutch is established when the accelerator is off, the difference in rotational speed between the two rotating elements engaged and released by the lockup clutch is automatically changed. Engagement control for engaging the lock-up clutch is started when the engagement threshold is not more than a predetermined threshold according to the gear position of the machine. In this way, since the engagement control of the lockup clutch is started using the engagement threshold value corresponding to the shift stage of the automatic transmission, it is possible to suppress a shock that may occur when the lockup clutch is engaged (locked up). Can do.

  In such an automatic transmission apparatus according to the present invention, the engagement threshold value may be a threshold value that is set to tend to decrease as the shift speed becomes lower. This is based on the fact that the lower the gear position, the higher the reduction ratio, and that a larger torque is considered to be transmitted when the lockup clutch is engaged. Therefore, in this way, it is possible to more appropriately suppress a shock that may occur when the lockup clutch is engaged (locked up). In this case, the engagement threshold value may be a threshold value having the same value at a shift speed higher than a predetermined shift speed. For example, when a 6-speed automatic transmission is provided, the engagement threshold corresponding to the 4th to 6th gears may be the same value. Furthermore, in this case, the product of the gear ratio of each gear and the engagement threshold is substantially constant when the gear ratio of the gear is used as the reduction gear ratio at the gear lower than the predetermined gear. It is also possible that the threshold is determined to be This is based on the fact that there is a correlation between the product of the gear ratio of the shift speed and the engagement threshold value and the shock at the time of engagement. As a result, the degree of suppression of shock that can occur when the lockup clutch is engaged (locked up) at each gear position can be made substantially the same.

  In the automatic transmission according to the aspect of the invention, the control unit may determine that the acquired rotational speed difference is greater than the engagement threshold until the lockup clutch is completely engaged after starting the engagement control. It may be a means for stopping the engagement control when the value reaches or exceeds a preset release threshold value. In this way, it is possible to avoid a shock when the lockup clutch is engaged in a state where the rotational speed difference is large. It should be noted that after the engagement control is stopped, the engagement control of the lockup clutch may be started when the rotational speed difference again becomes equal to or smaller than the engagement threshold value. That is, it is only necessary to redo the engagement control. Here, similarly to the engagement threshold value, the release threshold value can also be a threshold value set to tend to be smaller as the gear position becomes lower.

The lockup clutch engagement method of the present invention includes:
An engagement method of a lockup clutch in an in-vehicle automatic transmission comprising a fluid transmission device having a lockup clutch and a stepped automatic transmission,
When a condition for engaging the lock-up clutch is satisfied when the accelerator is off, the difference in rotational speed between the two rotating elements engaged and released by the lock-up clutch is the shift speed of the automatic transmission. Engage the lock-up clutch when it is below a predetermined engagement threshold that tends to be smaller as the speed is lower,
It is characterized by that.

  In this lockup clutch engagement method of the present invention, when the condition for engaging the lockup clutch is established when the accelerator is off, the rotational speeds of the two rotating elements that are engaged and disengaged by the lockup clutch. The lockup clutch is engaged when the difference is equal to or less than a predetermined engagement threshold corresponding to the shift stage of the automatic transmission. As described above, since the lockup clutch is engaged using the engagement threshold corresponding to the shift stage of the automatic transmission, it is possible to suppress a shock that may occur when the lockup clutch is engaged (locked up).

It is a block diagram which shows the outline of a structure of the motor vehicle 10 carrying the automatic transmission 20 as one Example of this invention. 1 is a configuration diagram showing an outline of a mechanical configuration of an automatic transmission 20. FIG. 3 is an explanatory diagram showing an operation table showing the relationship between each gear position of the automatic transmission 30 and the operation states of clutches C-1 to C-3 and brakes B-1 and B-2. 3 is an explanatory diagram illustrating a collinear diagram illustrating the relationship between rotational speeds between rotating elements constituting the automatic transmission 30. FIG. 2 is a configuration diagram showing an outline of a configuration of a hydraulic system for a lock-up clutch of a hydraulic circuit 50. FIG. It is explanatory drawing which shows an example of the shift map. FIG. 7 is an explanatory diagram showing a low vehicle speed portion (portion indicated by a one-dot chain line) in the shift map of FIG. 6 together with a lockup line of a lockup clutch. 4 is a flowchart illustrating an example of an accelerator-off lockup control routine that is executed by a transmission ECU 80; It is explanatory drawing which shows an example of a gear stage threshold value relationship map.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an automobile 10 equipped with an automatic transmission 20 as an embodiment of the present invention, and FIG. 2 is a configuration diagram showing an outline of a mechanical configuration of the automatic transmission 20. It is. As shown in FIGS. 1 and 2, an automobile 10 according to the embodiment includes an engine 12 as an internal combustion engine that outputs power by explosion combustion of hydrocarbon fuel such as gasoline and light oil, and an engine that controls the operation of the engine 12. Electronic control unit (hereinafter referred to as engine ECU) 16, fluid transmission device 22 attached to crankshaft 14 of engine 12, input shaft 31 is connected to the output side of fluid transmission device 22, and gear mechanism 48. And an output shaft 32 connected to the drive wheels 11a and 11b via the differential gear 49, a stepped automatic transmission 30 for shifting the power input to the input shaft 31 and transmitting it to the output shaft 32, and the fluid transmission device 22. And hydraulic circuit 50 for supplying hydraulic oil to automatic transmission 30, and fluid transmission device 22 and automatic transmission 30 by controlling hydraulic circuit 50. Control for transmission electronic control unit (hereinafter, transmission of ECU) includes a 80, a brake electronic control unit for controlling the electronically controlled hydraulic brake unit, not shown (hereinafter, the brake referred ECU) 17, a. Here, the automatic transmission 20 of the embodiment mainly corresponds to the automatic transmission 30, the hydraulic circuit 50, and the transmission ECU 80.

  The engine ECU 16 is configured as a microprocessor centered on a CPU, and includes a ROM that stores a processing program, a RAM that temporarily stores data, an input / output port, and a communication port in addition to the CPU. The engine ECU 16 includes signals from various sensors for detecting the operating state of the engine 12 such as an engine rotational speed Ne from a rotational speed sensor 14 a attached to the crankshaft 14 and an accelerator opening Acc as an amount of depression of the accelerator pedal 93. Signals such as the accelerator opening Acc from the accelerator pedal position sensor 94 to be detected and the vehicle speed V from the vehicle speed sensor 98 are input via the input port, and the engine ECU 16 drives the throttle motor that drives the throttle valve. A signal, a control signal to the fuel injection valve, an ignition signal to the spark plug, and the like are output via the output port.

  As shown in FIG. 2, the fluid transmission device 22 is configured as a fluid torque converter with a lock-up clutch, and serves as an input-side fluid transmission element connected to the crankshaft 14 of the engine 12 via the front cover 18. Of the pump impeller 23, a turbine runner 24 as an output side fluid transmission element connected to the input shaft 31 of the automatic transmission 30 via a turbine hub, and the turbine runner disposed inside the pump impeller 23 and the turbine runner 24. The stator 25 which rectifies | straightens the flow of the hydraulic oil from 24 to the pump impeller 23, the one-way clutch 26 which restrict | limits the rotation direction of the stator 25 to one direction, and the lockup clutch 28 which has a damper mechanism are provided. When the difference in rotational speed between the pump impeller 23 and the turbine runner 24 is large, the fluid transmission device 22 functions as a torque amplifier by the action of the stator 25, and the difference in rotational speed between the pump impeller 23 and the turbine runner 24 is small. Sometimes it functions as a fluid coupling. The lock-up clutch 28 can execute lock-up and release of lock-up for connecting the pump impeller 23 (front cover 18) and the turbine runner 24 (turbine hub). When the up-on condition is satisfied, the pump impeller 23 and the turbine runner 24 are locked up by the lock-up clutch 28, and the power from the engine 12 is mechanically and directly transmitted to the input shaft 31. At this time, the fluctuation of the torque transmitted to the input shaft 31 is absorbed by the damper mechanism.

  The lock-up clutch 28 changes the pressure in the lock-up off chamber 22b facing the fluid transmission chamber 22a in which the pump impeller 23 and the turbine runner 24 of the fluid transmission device 22 are disposed via the lock-up piston 28p. It is configured to perform lockup and unlocking. That is, when the pressure in the lockup off chamber 22b is higher than the pressure in the fluid transmission chamber 22a, or when the pressure in the fluid transmission chamber 22a and the pressure in the lockup off chamber 22b are equal, the lockup piston 28p does not move to the engagement side, and lockup is not executed (released). On the other hand, when a pressure lower than the pressure in the fluid transmission chamber 22a is supplied into the lock-up off chamber 22b and the pressure in the lock-up off chamber 22b decreases, the lock-up piston 28p moves toward the front cover 18 and causes friction. The material is pressed against the inner surface of the front cover 18, whereby lockup is executed (completed).

  The automatic transmission 30 is configured as a stepped transmission with six speeds, and includes a single pinion planetary gear mechanism 35, a Ravigneaux planetary gear mechanism 40, and three clutches C-1, C-2, C-. 3 and two brakes B-1, B-2 and a one-way clutch F-1. The single pinion type planetary gear mechanism 35 includes a sun gear 36 as an external gear, a ring gear 37 as an internal gear disposed concentrically with the sun gear 36, and a plurality of gears meshed with the sun gear 36 and meshed with the ring gear 37. The pinion gear 38 and a carrier 39 that holds the plurality of pinion gears 38 so as to rotate and revolve freely. The sun gear 36 is fixed to the case, and the ring gear 37 is connected to the input shaft 31. The Ravigneaux planetary gear mechanism 40 includes two sun gears 41a and 41b as external gears, a ring gear 42 as an internal gear, a plurality of short pinion gears 43a meshing with the sun gear 41a, a sun gear 41b and a plurality of short pinion gears 43a. The sun gear 41a includes a plurality of long pinion gears 43b that mesh with the ring gear 42 and a carrier 44 that holds the plurality of short pinion gears 43a and the plurality of long pinion gears 43b so as to rotate and revolve. 1 is connected to the carrier 39 of the single-pinion type planetary gear mechanism 35, the sun gear 41b is connected to the carrier 39 via the clutch C-3, and is connected to the case via the brake B-1, and the ring gear 42 Is connected to the output shaft 32 and A 44 is connected to the input shaft 31 via the clutch C-2. The carrier 44 is connected to the case via the brake B2 and to the case via the one-way clutch F-1. FIG. 3 shows an operation table showing the relationship between the respective speeds of the automatic transmission 30 and the operating states of the clutches C-1 to C-3 and the brakes B-1 and B-2, and FIG. The collinear diagram which illustrates the relationship of the rotational speed between the rotation elements which comprise is shown. As shown in the operation table of FIG. 3, the automatic transmission 30 is turned on / off of the clutches C-1 to C-3 (on is engaged and off is released) and the brakes B-1 and B-2 are turned on / off. Can be switched between forward 1st to 6th, reverse and neutral.

  The fluid transmission device 22 and the automatic transmission 30 are operated by a hydraulic circuit 50 that is driven and controlled by the transmission ECU 80. Although not shown, the hydraulic circuit 50 is an oil pump that pumps hydraulic oil using power from the engine 12, a primary regulator valve that regulates hydraulic oil from the oil pump and generates a line pressure PL, and a primary regulator A secondary regulator valve that reduces the line pressure PL from the valve to generate the secondary pressure Psec, a modulator valve that adjusts the line pressure PL from the primary regulator valve to generate a constant modulator pressure Pmod, and an operating position of the shift lever 91 Correspondingly, adjust the line pressure PL from the manual valve and manual valve to switch the supply destination (clutch C-1 to C-3 and brakes B-1, B-2) of the line pressure PL from the primary regulator valve. Clutch C-1 to C-3 and brake Comprising a like plurality of the linear solenoid valve for generating a solenoid pressure to the B-1, B-2.

  Further, the hydraulic circuit 50 adjusts the modulator pressure Pmod from the modulator valve to generate the lockup solenoid pressure Pslu as shown in FIG. 5 in order to operate the lockup clutch 28 of the fluid transmission device 22. Solenoid valve SLU, lockup control valve 52 for generating lockup clutch pressure Pluc to lockup clutch 28 according to lockup solenoid pressure Pslu from lockup solenoid valve SLU, and lockup off chamber of fluid transmission device 22 And a lockup relay valve 54 that permits and regulates the supply of the lockup clutch pressure Pluc from the lockup control valve 52 to 22b. Hereinafter, a portion related to the operation of the lockup clutch 28 in the hydraulic circuit 50 is referred to as a lockup clutch hydraulic system.

  The lockup solenoid valve SLU adjusts the modulator pressure Pmod from the modulator valve according to the current value applied from the auxiliary battery (not shown) to generate the lockup solenoid pressure Pslu. Controlled by. The lock-up control valve 52 adjusts the secondary pressure Psec from the secondary regulator valve in accordance with the lock-up solenoid pressure Pslu as the signal pressure supplied from the lock-up solenoid valve SLU, and lock-up clutch pressure to the lock-up clutch 28. This is a spool valve for generating a Pluc. In the embodiment, the lockup control valve 52 generates a lockup clutch pressure Pluc by reducing the secondary pressure Psec, which is the original pressure, as the lockup solenoid pressure Pslu from the lockup solenoid valve SLU increases. When the pressure Pslu is equal to or higher than the lockup engagement pressure P1, the lockup clutch pressure Pluc required for complete engagement of the lockup clutch 28 is output. The lockup relay valve 54 is a spool valve that inputs the lockup solenoid pressure Pslu supplied from the lockup solenoid valve SLU as a signal pressure. In the embodiment, the lockup relay valve 54 supplies the secondary pressure Psec from the secondary regulator valve to the lockup off chamber 22b when the lockup solenoid pressure Pslu is not supplied from the lockup solenoid valve SLU, and the lockup solenoid valve SLU. When the lockup solenoid pressure Pslu is supplied from the secondary pressure valve, the secondary pressure Psec from the secondary regulator valve is supplied to the fluid transmission chamber 22a and the lockup clutch pressure Pluc from the lockup control valve 52 is supplied to the lockup off chamber 22b. It was supposed to be configured.

  In the lockup clutch hydraulic system thus configured, when the lockup solenoid pressure Pslu is not generated by the lockup solenoid valve SLU, the hydraulic oil (secondary pressure Psec) is supplied from the lockup relay valve 54 to the lockup off chamber 22b. In addition, since the hydraulic oil flows from the lock-up off chamber 22b into the fluid transmission chamber 22a and the lock-up off chamber 22b and the fluid transmission chamber 22a have the same pressure, the lock-up is not executed (released). A part of the hydraulic oil that has flowed into the fluid transmission chamber 22a from the lockup off chamber 22b flows out to the lockup relay valve 54 side through the hydraulic oil inlet / outlet. On the other hand, when the lockup solenoid pressure Pslu generated by the lockup solenoid valve SLU is supplied to the lockup control valve 52 and the lockup relay valve 54, the lockup clutch pressure Pluc (secondary) generated by the lockup control valve 52 is set. Pressure lower than the pressure Psec) is supplied from the lockup relay valve 54 to the lockup off chamber 22b, and the secondary pressure Psec from the secondary regulator valve is supplied from the lockup relay valve 54 to the fluid transmission chamber 22a. When the lockup piston 28p moves to the engagement side as the pressure in the lockup off chamber 22b decreases, and the lockup solenoid pressure Pslu reaches or exceeds the lockup engagement pressure P1, the lockup clutch 2 Is completely engaged lock-up is completed.

  The transmission ECU 80 is configured as a microprocessor centered on a CPU, and includes a ROM that stores a processing program, a RAM that temporarily stores data, an input / output port, and a communication port in addition to the CPU. . The transmission ECU 80 includes an input shaft rotational speed Nin from the rotational speed sensor 31 a attached to the input shaft 31, an output shaft rotational speed Nout from the rotational speed sensor 32 a attached to the output shaft 32, and the position of the shift lever 91. The shift position SP from the shift position sensor 92 for detecting the acceleration, the accelerator opening Acc from the accelerator pedal position sensor 94, the brake pedal position BP from the brake pedal position sensor 96 for detecting the depression amount of the brake pedal 95, and the vehicle speed sensor 98 Vehicle speed V and the like are input via an input port, and a control signal to the hydraulic circuit 50 is output from the transmission ECU 80 via an output port.

  The engine ECU 16, the brake ECU 17, and the transmission ECU 80 are connected to each other via a communication port, and exchange various control signals and data necessary for control with each other. Further, as the shift position SP of the shift lever 91, in the embodiment, a parking position (P position) used at the time of parking, a reverse position (R position) for reverse travel, a neutral position (N position), and a forward travel position are used. A normal drive position (D position), an upshift instruction position, and a downshift instruction position are prepared.

  FIG. 6 is an explanatory diagram showing an example of the shift map, and FIG. 7 is an explanatory diagram showing the low vehicle speed portion (portion indicated by the alternate long and short dash line) in the shift map of FIG. 6 together with the lockup line of the lockup clutch. is there. In the automatic transmission 20 of the embodiment, when the shift position SP of the shift lever 91 is the drive position (D position), as shown in the shift map of FIG. -2 upshift line, 2-3 upshift line, 3-4 upshift line, 4-5 upshift line, and 5-6 upshift line are shifted to the left or lower gears (for example, 2-3 upshift line) When shifting from the left side to the right side in the state of the first speed to the second speed), the clutches C-1 to C-3 are upshifted from the current gear position to the gear position of the right number (for example, the third speed in the 2-3 upshift line). C-3 and brakes B-1 and B-2 are turned on and off, and the operating point consisting of the accelerator opening Acc and the vehicle speed V is the 6-5 downshift line, 5- The downshift line, 4-3 downshift line, 3-2 downshift line, and 2-1 downshift line are in the state of gears higher than the left number (for example, 4th to 6th speed on the 4-3 downshift line). When shifting from the right side to the left side, the clutches C-1 to C-3 and the brakes B-1 and B-1 are used to downshift from the current gear to the right gear (for example, the third gear in the 4-3 downshift line). Turn B-2 on and off. Further, as shown in FIG. 7, the automatic transmission 20 of the embodiment has an operating point that is composed of the accelerator opening Acc and the vehicle speed V when the lock-up clutch 28 is off at each of the second to sixth shift speeds. The lockup clutch 28 is locked up when it reaches the region on the right side of the lockup line (2ON line to 6ON line in FIG. 7) for each gear position, and the accelerator is opened with the lockup clutch 28 locked up. When the operating point consisting of the degree Acc and the vehicle speed V exceeds the upshift line and the downshift line to change the gear stage of the automatic transmission 30, the lockup clutch 28 is unlocked prior to the gear stage change. The

  Next, the operation of the automatic transmission 20 according to the embodiment, particularly the operation when the lockup clutch 28 of the fluid transmission device 22 is locked up when the accelerator is off (coast state) will be described. FIG. 8 is a flowchart illustrating an example of an accelerator-off lockup control routine executed by the transmission ECU 80. In this routine, the operating point consisting of the accelerator opening degree Acc and the vehicle speed V reaches the region on the right side of the lockup line for each shift stage when the accelerator is off and the lockup clutch 28 is off at each shift stage. This is executed when the operating point is in the region on the right side of the lock-up line with respect to the changed gear after the change of the gear of the automatic transmission 30. For example, when the vehicle is traveling at the fourth speed with the lock-up clutch 28 unlocked at the operation point P1 in FIG. 7, the accelerator is turned off and the operation point P2 is reached. When the 4-3 downshift line on the way to the operating point P3 is exceeded, immediately after the shift stage is changed from the 4th speed to the 3rd speed or on the 3-2 downshift line on the way from the operating point P3 to the operating point P4 This is executed immediately after the gear position is changed from the third speed to the second speed. In the embodiment, it is determined that the accelerator is off when the accelerator opening degree Acc from the accelerator pedal position sensor 94 is 0. Therefore, acquisition of the accelerator off is realized by inputting the accelerator opening Acc having a value of 0 from the accelerator pedal position sensor 94.

  When the accelerator-off lockup control routine is executed, the transmission ECU 80 first sets an engagement threshold value Non and a release threshold value Noff corresponding to the gear stage G of the automatic transmission 30 (step S100). Here, the engagement threshold value Non is the rotation of the crankshaft 14 and the input shaft 31 that does not cause a shock due to the lockup of the lockup clutch 28 even when the lockup clutch 28 is locked up (lockup control) is started. The release threshold value Noff is set as a speed difference. After the lockup control is started, the rotational speed difference between the crankshaft 14 and the input shaft 31 becomes large, and the lockup clutch 28 is locked up with a shock. In order to avoid this, the rotational speed difference between the crankshaft 14 and the input shaft 31 for stopping the lockup control is set as a value larger than the engagement threshold value Non corresponding to the gear stage G. In the embodiment, the relationship between the shift speed G and the engagement threshold value Non and the relationship between the shift speed G and the release threshold value Noff is determined in advance and stored as a shift speed threshold value relationship map. This is performed by deriving the threshold value Non and the release threshold value Noff. An example of the shift speed threshold relationship map is shown in FIG. As shown in the figure, the engagement threshold value Non is set to a smaller value when the shift speed G is from the 2nd speed to the 4th speed, and becomes the same as the shift speed G is from the 4th speed to the 6th speed. Is set as the value of As described above, the engagement threshold value Non is set to a smaller value as the shift speed G becomes lower. The speed reduction ratio increases as the shift speed G becomes lower, and a large torque is transmitted when the lockup clutch 28 is locked up. Is based on what is thought to be done. In the embodiment, the product of the gear ratio of each gear and the engagement threshold value Non at each gear when the gear ratio of the second gear to the fourth gear is used as the reduction gear ratio, that is, The gear ratio of the second speed to the fourth speed is G2, G3, G4 (for example, 2.0, 1.5, 1.0), and the engagement threshold value Non from the second speed to the fourth speed is Non2. , Non3, Non4 (for example, 40, 60, 80 illustrated in FIG. 9), the engagement threshold value Non from the second speed to the fourth speed is set so that the following expression (1) is satisfied. This is based on the fact that there is a correlation between the product of the gear ratio of the gear position and the engagement threshold value Non and the shock that may occur when the lockup clutch 28 is locked up.

  G2 / Non2≈G3 / Non3≈G4 / Non4 (1)

  When the engagement threshold value Non and the release threshold value Noff are thus set, the engine rotation speed Ne from the rotation speed sensor 14a and the input shaft rotation speed Nin from the rotation speed sensor 31a are input (step S110), and the input engine rotation is input. A rotational speed difference ΔN as a difference between the speed Ne and the input shaft rotational speed Nin is calculated (step S120), and it is determined whether the rotational speed difference ΔN is equal to or less than the engagement threshold value Non (step S130). When the difference ΔN is equal to or smaller than the engagement threshold value Non, lockup control for locking up the lockup clutch 28 is started (step S140). When the rotational speed difference ΔN is larger than the engagement threshold value Non, the processes of steps S110 to S130 are repeated. The rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin Is waiting for the engagement threshold value Non or less. Thus, the lockup control is started when the rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin is equal to or less than the engagement threshold value Non set according to the gear stage G. A shock that may occur when the up clutch 28 is locked up can be suppressed. The lockup control is started by starting an operation of supplying the lockup solenoid pressure Pslu generated by the lockup solenoid valve SLU to the lockup control valve 52 and the lockup relay valve 54.

  When the lockup control is started, the rotation speed difference ΔN as a difference between the engine rotation speed Ne and the input shaft rotation speed Nin becomes a value of 0, and the rotation is continued until the lockup clutch 28 is completely locked up (engaged). Processing for inputting the engine rotational speed Ne from the speed sensor 14a and the input shaft rotational speed Nin from the rotational speed sensor 31a (step S160), and the rotational speed as a difference between the input engine rotational speed Ne and the input shaft rotational speed Nin. A process for calculating the difference ΔN (step S160), a process for determining whether or not the rotational speed difference ΔN is less than the release threshold value Noff (step S170), and whether or not the rotational speed difference ΔN is less than or equal to the engagement threshold value Non. The determination process (step S180) is repeated until the rotational speed difference ΔN becomes 0 and the lockup clutch 28 is completely locked up. The routine ends.

  On the other hand, when the rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin increases after the lockup control is started and exceeds the release threshold value Noff, the rotational speed difference ΔN is canceled in step S180. It is determined that the value is equal to or greater than the threshold value Noff, the lockup control is stopped (step S190), and this routine is terminated. Thus, after the lockup control is started, the rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin is equal to or greater than the release threshold value Noff set to be larger than the engagement threshold value Non corresponding to the gear stage G. Since the lockup control is stopped when the engine speed reaches, the lockup clutch 28 is prevented from being locked up with a shock when the rotational speed difference ΔN between the engine rotational speed Ne and the input shaft rotational speed Nin is large. Can do. The stop of the lockup control is performed by stopping the generation of the lockup solenoid pressure Pslu by the lockup solenoid valve SLU, similarly to the operation for releasing the lockup of the lockup clutch 28. When the condition for executing the accelerator-off lock-up control routine of FIG. 7 is satisfied when the lock-up control is stopped, that is, the accelerator is off and the lock-up clutch 28 is off at each gear position. When the operating point consisting of the accelerator opening Acc and the vehicle speed V is in the region on the right side of the lockup line for each gear position, the accelerator-off lockup control routine of FIG. 7 is immediately executed, and the processing of this routine is performed. Lock-up clutch 28 is locked up.

  According to the automatic transmission 20 of the embodiment described above, the lockup with respect to the shift stage G is performed as a condition for locking up the lockup clutch 28 from the coast state where the accelerator is off and the lockup clutch 28 is unlocked. When the condition reaching the area on the right side of the line (2 ON line to 6 ON line in FIG. 7) is satisfied, the control (lock-up control) for locking up the lock-up clutch 28 according to the gear stage G is started. A predetermined engagement threshold value Non is set as a rotational speed difference between the crankshaft 14 and the input shaft 31 where no shock is generated by the lockup of the lockup clutch 28, and the difference between the engine rotational speed Ne and the input shaft rotational speed Nin is set. As the rotation speed difference ΔN is less than or equal to the engagement threshold value Non set according to the gear stage G It can be suppressed by starting the lock-up control, a shock that may occur when the lockup lockup clutch 28 in any gear when. In addition, the rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin until the lockup clutch 28 is completely locked up after the lockup control is started is engaged according to the gear stage G. Locking up with a shock when the rotational speed difference ΔN between the engine rotational speed Ne and the input shaft rotational speed Nin is large by stopping the lock-up control when the release threshold Noff that is set larger than the threshold Non is reached. It is possible to avoid the up clutch 28 from being locked up.

  In the automatic transmission 20 according to the embodiment, a lockup line for locking up the lockup clutch 28 is set at each of the second to sixth gears, and the engagement threshold value Non is set for each of the second to sixth gears. Although the release threshold value Noff is set, the lockup line may be set for the first speed and the engagement threshold value Non and the release threshold value Noff may be set. That is, the lockup line may be set for all the shift speeds, and the engagement threshold value Non and the release threshold value Noff may be set. In the embodiment, when the lockup line is set for the first speed, for example, a value 20 may be set for the engagement threshold value Non and a value 40 may be set for the release threshold value Noff.

  In the automatic transmission 20 according to the embodiment, as the engagement threshold value Non, a smaller value is set as the shift stage G becomes the lower speed side from the second speed to the fourth speed, and the shift stage G is changed from the fourth speed to the sixth speed. Up to this point, the same value is set. However, it may be set so that the shift stage G becomes smaller as the shift stage G becomes the lower speed side even when the shift stage G is from the fourth speed to the sixth speed. In this case, similarly, the release threshold value Noff may be set so as to become smaller as the shift speed G becomes lower than the fourth speed to the sixth speed. For example, the fifth-speed engagement threshold value Non may be set to a value 100, or the sixth-speed engagement threshold value Non may be set to a value 120, for the example of the shift speed threshold value relationship map of FIG.

  In the automatic transmission 20 according to the embodiment, as the engagement threshold value Non, the product of the gear ratio of each shift stage and the engagement threshold value Non at each shift stage when the gear ratio of each shift stage is used as the reduction ratio is substantially the same. However, the product of the gear ratio of each shift stage and the engagement threshold value Non at each shift stage may not be substantially the same. In this case, it is preferable to make it smaller than the product value when the product of the gear ratio of each gear and the engagement threshold value Non at each gear is substantially the same. For example, the second-speed engagement threshold value Non may be set to a value 30 or the third-speed engagement threshold value Non may be set to a value 50 in the example of the shift speed threshold relationship map of FIG.

  In the automatic transmission 20 according to the embodiment, the rotational speed difference ΔN as the difference between the engine rotational speed Ne and the input shaft rotational speed Nin is canceled until the lockup clutch 28 is completely locked up after the lockup control is started. The lock-up control is stopped when reaching the threshold value Noff or higher, but the lock-up control may not be stopped even when the rotational speed difference ΔN reaches the release threshold value Noff or higher.

  In the automatic transmission 20 according to the embodiment, the operating point consisting of the accelerator opening Acc and the vehicle speed V exceeds the upshift line and the downshift line when the lockup clutch 28 is locked up, and the automatic transmission 30 shifts. When changing the gear, the lockup of the lockup clutch 28 is released prior to changing the gear, but the gear of the automatic transmission 30 is changed while the lockup of the lockup clutch 28 is held. It does not matter.

  In the automatic transmission device 20 of the embodiment, the 6-speed automatic transmission 30 is used. However, a 3-speed, 4-speed, 5-speed automatic transmission may be used, and a 7-speed, 8-speed or higher speed may be used. An automatic transmission may be used.

  In the embodiment, the present invention has been described as a form of the automatic transmission 20, but it may be a form of a lockup clutch engagement method.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the example,
The lockup clutch 28 corresponds to a “lockup clutch”, the fluid transmission device 22 corresponds to a “fluid transmission device”, the automatic transmission 30 corresponds to an “automatic transmission”, and the accelerator pedal position sensor 84 opens the accelerator. The transmission ECU 80 that obtains the degree Acc corresponds to “accelerator off obtaining means”, obtains the engine rotational speed Ne from the crankshaft 14, obtains the input shaft rotational speed Nin from the rotational speed sensor 31 a, and obtains the rotational speed difference as a difference between them. The transmission ECU 80 that executes the processing of steps S110, S120, S150, and S160 of the accelerator-off lockup control routine of FIG. 8 for calculating ΔN corresponds to “rotational speed difference acquisition means”, and is in the accelerator-off coast state. The lock-up clutch 28 is unlocked from the unlocked state. As a condition for locking up the clutch 28, the accelerator-off lockup control routine of FIG. 8 is executed when the condition reaching the region on the right side of the lockup line (2ON line to 6ON line in FIG. 7) for the gear stage G is satisfied. The transmission ECU 80 that executes the processes of Steps 140 and S150 corresponds to “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of automatic transmissions.

  DESCRIPTION OF SYMBOLS 10 Car, 11a, 11b Drive wheel, 12 Engine, 14 Crankshaft, 14a Rotational speed sensor, 16 Engine electronic control unit (engine ECU), 18 Front cover, 20 Power transmission device, 22 Fluid transmission device, 22a Fluid transmission chamber 22b Lock-up off chamber, 23 Pump impeller, 24 Turbine runner, 25 Stator, 26 One-way clutch, 28 Lock-up clutch, 28p Lock-up piston, 30 Automatic transmission, 31 Input shaft, 31a Rotational speed sensor, 32 Output shaft, 32a Rotational speed sensor, 35 planetary gear mechanism, 36 sun gear, 37 ring gear, 38 pinion gear, 39 carrier, 40 planetary gear mechanism, 41a sun gear, 41b sun gear, 42 ring gear, 43a short pinio Gear, 43b long pinion gear, 44 carrier, 48 gear mechanism, 49 differential gear, 50 hydraulic circuit, 52 lockup control valve, 54 lockup relay valve, 80 electronic control unit for transmission (transmission ECU), 90 main electronic control Unit (main ECU), 91 shift lever, 92 shift position sensor, 93 accelerator pedal, 94 accelerator pedal position sensor, 95 brake pedal, 96 brake switch, 98 vehicle speed sensor, B1, B2 brake, C1-C3 clutch, F1 one-way clutch .

Claims (6)

An on-vehicle automatic transmission comprising a fluid transmission device having a lock-up clutch and a stepped automatic transmission,
An accelerator off acquisition means for acquiring the accelerator off;
A rotational speed difference acquisition means for acquiring a rotational speed difference between two rotational elements engaged and disengaged by the lock-up clutch;
When the condition for engaging the lockup clutch is established in a state where the accelerator-off is acquired, the acquired rotational speed difference is equal to or less than an engagement threshold predetermined according to the shift stage of the automatic transmission. Control means for starting engagement control for engaging the lock-up clutch at the time of,
An automatic transmission comprising: The automatic transmission according to claim 1,
The engagement threshold is a threshold determined to tend to decrease as the shift speed becomes lower.
Automatic transmission. The automatic transmission according to claim 2, wherein
The engagement threshold value is a threshold value having the same value in a shift stage on a higher speed side than a predetermined shift stage.
Automatic transmission. The automatic transmission according to claim 3, wherein
The engagement threshold is determined so that the product of the gear ratio of each gear and the engagement threshold is substantially constant when the gear ratio of the gear is used as a reduction gear ratio at a gear lower than the predetermined gear. Threshold,
Automatic transmission. The automatic transmission according to any one of claims 1 to 4, wherein
The control means starts the engagement control and the acquired rotational speed difference is greater than or equal to a preset release threshold value that is larger than the engagement threshold value until the lockup clutch is completely engaged. It is a means to stop the engagement control when it reaches,
Automatic transmission. An engagement method of a lockup clutch in an in-vehicle automatic transmission comprising a fluid transmission device having a lockup clutch and a stepped automatic transmission,
When the condition for engaging the lock-up clutch is satisfied when the accelerator is off, the rotational speed difference between the two rotating elements that are engaged and disengaged by the lock-up clutch becomes the shift stage of the automatic transmission. And engaging the lock-up clutch when it is below a predetermined engagement threshold.
A lockup clutch engagement method characterized by the above.

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