JP4541673B2 - Shift control device for automatic transmission - Google Patents

Description

  The present invention relates to a shift control device for an automatic transmission including a friction engagement element such as a shift clutch that automatically performs a shift operation by switching a power transmission path including a plurality of shift gear trains.

  2. Description of the Related Art Conventionally, in a vehicle, an automatic shift that automatically performs a shift operation by switching a power transmission path including a plurality of shift gear trains by selectively engaging and controlling friction engagement elements such as a shift clutch and a brake. The machine is widely adopted.

By the way, in recent years, the shift time of the automatic transmission (fastening operation time of the friction engagement element) tends to increase for the purpose of increasing the output of the engine and improving the shift quality of the automatic transmission. In an automatic transmission, the amount of heat generated during a fastening operation of a frictional engagement element used for shifting tends to increase. In this case, the frictional engagement element that has become high temperature due to heat generation during the shifting operation is cooled to a temperature equivalent to the oil temperature of the ATF mainly by heat exchange with the hydraulic fluid (ATF) of the automatic transmission. Suppressing the rise in the oil temperature of ATF is an important requirement for protecting the facing of each friction engagement element from thermal damage such as burning. Thus, for example, Patent Document 1 discloses a technique for detecting the ATF oil temperature and continuously reducing the torque generated by the engine when the detected oil temperature is equal to or higher than a predetermined temperature.
Japanese Patent Laid-Open No. 10-169483

  However, a predetermined heat release time is required until the heat generated in each friction engagement element is cooled by heat exchange with the ATF, and until the heat release is completed, the temperature of the friction engagement element and the ATF A predetermined temperature difference occurs between the temperature. Therefore, as in the technique disclosed in Patent Document 1 described above, merely suppressing the ATF oil temperature rise may not be sufficient as a heat damage countermeasure for the friction engagement element. That is, particularly when traveling on a continuous curved road, the speed change control is repeatedly performed, and the same friction engagement element may be frequently engaged in a short time. Even when the oil temperature is low, a large amount of heat may be stored in the frictional engagement elements, which may cause burning of the facing.

  The present invention has been made in view of the above circumstances, and provides a shift control device for an automatic transmission capable of protecting a friction engagement element from heat damage in response to a traveling state in which shift control is frequently performed. The purpose is to do.

The present invention provides a shift control device for an automatic transmission that selectively controls engagement of a plurality of friction engagement elements to perform shift control of the transmission, wherein the plurality of friction engagement elements are controlled during a shift operation of the automatic transmission. Of these, a calorific value calculating means for calculating the respective calorific values of the friction engagement elements that are engaged, and a friction engagement element that is not engaged among the plurality of friction engagement elements during the shift operation of the automatic transmission. A heat release amount calculating means for calculating a heat amount and calculating a heat release amount of each of the plurality of friction engagement elements during a non-shifting operation of the automatic transmission, a heat generation amount calculated by the heat generation amount calculation means, and the heat release amount calculation means The heat storage amount calculation means for cumulatively calculating the heat storage amount for each friction engagement element based on the heat dissipation amount calculated in step (b), and the friction engagement element whose heat storage amount calculated by the heat storage amount calculation means is a set value or more Less when there is Also, and a speed change timing setting means for heat storage amount is set to upshift timing to shift speed with the frictional engagement element set value or more in a timing earlier than when the heat storage amount is equal to or less than the set value, the heat storage The amount calculation means sets a lower limit value based on the oil temperature of the hydraulic oil in the transmission, and corrects the heat storage amount to the lower limit value when the heat storage amount falls below the lower limit value. To do.

  According to the shift control device for an automatic transmission of the present invention, it is possible to protect the friction engagement element from heat damage in response to a traveling state in which shift control is frequently performed.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the entire control system of an automatic transmission, FIG. 2 is a skeleton diagram showing an outline of the transmission, FIG. 3 is a circuit diagram of a transmission control device, and FIG. FIG. 5 is a characteristic diagram of the shift map, FIG. 6 is a map showing the relationship between the clutch differential rotation speed and the input torque, and FIG. 7 is a time chart showing an example of the transition of the calculated clutch heat storage amount. It is.

  In FIG. 1, reference numeral 1 denotes an engine, and a transmission 3 is connected to a crankshaft 1 a (see FIG. 2) of the engine 1 via a torque converter 2.

  As shown in FIG. 2, the torque converter 2 includes a front cover 5 connected to the crankshaft 1 a of the engine 1 in a converter case 4 connected to the engine 1, and a pump-side case 6 connected to the front cover 5. The principal part is comprised. A pump impeller 7 is provided in the pump-side case 6, and a turbine runner 8 that is directly connected to the input shaft 9 of the transmission 3 is opposed to the pump impeller 7. An oil pump 11 is connected to the pump-side case 6 via a hydraulic pump shaft 10, and the oil pump 11 is directly rotated by the driving force of the engine 1 input via the crankshaft 1a. The

  The oil pump 11 generates hydraulic pressure in the hydraulic oil (ATF) in the transmission 3, and the hydraulic pressure generated by the oil pump 11 is supplied to the torque converter 2 and each lubricating portion of the transmission 3. And each friction engagement element (described later).

  A stator 13 supported by a one-way clutch 12 is disposed between the pump impeller 7 and the turbine runner 8. Further, a lockup clutch 14 that engages with the front cover 5 is attached to the turbine runner 8. When the lockup clutch 14 is engaged with the front cover 5, the crankshaft 1 a, the input shaft 9, Is directly connected.

  The transmission 3 includes a front planetary gear mechanism 21 and a rear planetary gear mechanism 22 that are disposed on the input shaft 9 in a transmission case 20 that is connected to the converter case 4, and a main part is configured.

  More specifically, a high clutch drum 25 is fixed to the input shaft 9, and a high clutch hub 26 is provided inside the high clutch drum 25. Further, a high clutch 27 as a friction engagement element is provided between the high clutch drum 25 and the high clutch hub 26.

  Further, the high clutch hub 26 is connected to a front carrier 23 on which a plurality of front planetary pinion gears 28 constituting a front planetary gear mechanism 21 are rotatably supported, and a front sun gear meshing with the front planetary pinion gears 28. A brake hub 30 is connected to 29. A reverse clutch 31 as a friction engagement element is provided between the brake hub 30 and the high clutch drum 25. Further, a friction engagement element is provided between the brake hub 30 and the transmission case 20. A 2 & 4 brake 32 is provided.

  A low clutch drum 33 is connected to the front carrier 23, and a low and reverse brake hub 34 is connected to the low clutch drum 33. The inner circumference of the low & reverse brake hub 34 is rotatably supported by the transmission case 20 via a low one-way clutch 35. Further, a frictional engagement is established between the low & reverse brake hub 34 and the transmission case 20. A low & reverse brake 36 is provided as a combination element.

  A rear carrier 24 disposed coaxially with the input shaft 9 is connected to a front ring gear 37 that meshes with each front planetary pinion gear 28 on the outer periphery of the front sun gear 29, and an output shaft 38 is connected to the rear carrier 24. Has been. A plurality of rear planetary pinion gears 39 constituting the rear planetary gear mechanism 22 are rotatably supported between the front ring gear 37 and the output shaft 38, and the rear sun gear 40 meshing with each rear planetary pinion gear 39 is an input shaft. 9 is connected. A low clutch 42 as a friction engagement element is provided between the rear ring gear 41 that meshes with each rear planetary pinion gear 39 on the outer periphery of the rear sun gear 40 and the low clutch drum 33.

  Each friction engagement element (clutch and brake) in the transmission 3 is spline-fitted to a plurality of annular inner disks that are spline-fitted outside the clutch hub and the like, and members inside the clutch drum and the transmission case 20 and the like. And a combined outer disk. Each friction engagement element is in a fastening state when the inner disk and the outer disk are pressed by a hydraulic piston (not shown) and frictionally engaged, and is released when the pressure of the hydraulic piston is released. It becomes a state. Each hydraulic piston is actuated by the ATF hydraulic pressure supplied from the oil pump 11, and the hydraulic pressure supplied to each hydraulic piston is an oil pan (see FIG. It is controlled by a transmission control unit (TCU) 50 through a control valve body 49 in the control valve body 49. In the transmission 3, the frictional engagement elements are selectively controlled by the TCU 50 to achieve four forward speeds and one reverse speed, which are transmitted from the torque converter 2 to the input shaft 9. After the engine driving force is shifted at a predetermined gear ratio, it is transmitted to driving wheels (not shown) via the output shaft 38.

  As shown in FIG. 3, the TCU 50 includes a CPU 51, a ROM 52, a RAM 53, an input interface 54, and an output interface 55, which are connected to each other via a bus line. Further, the TCU 50 is provided with a constant voltage circuit 62 connected to the battery 61 via the ignition switch 60, and when the ignition switch 60 is turned on, a stabilizing voltage is supplied to each part of the TCU 50. ing.

The input interface 54 includes an input shaft rotational speed sensor 65a for detecting the rotational speed N1 of the input shaft 9 of the transmission 3, an output shaft rotational speed sensor 65b for detecting the rotational speed N2 of the output shaft 38 of the transmission 3, and an ATF. An oil temperature sensor 66 that detects the oil temperature T, a range detection sensor 67 that detects a selection range of a select lever 68a (see FIG. 1) provided in the speed change operation unit 68, and a throttle opening Th of the engine 1 are detected. A throttle opening sensor 69 is connected, and the current gear stage Tp is input from the transmission 3. Further, an engine control unit (ECU) 70 that controls the engine 1 is connected to the input interface 54, and detection signals of various sensors and switches are input via the ECU 70. As is well known, the shift operation unit 68 is used by the driver to select a travel range, a neutral range, and a parking range by operating the select lever 68a. When the range is detected, automatic transmission control of the transmission 3 by the TCU 50 is performed.

  The automatic shift control will be described in detail. In the ROM 52 of the TCU 50, for example, as shown in FIGS. 5A and 5B, the normal shift map and the vehicle speed side lower than the normal shift map are displayed. The high-temperature shift map in which the respective fast shift timings are set is stored, and the TCU 50 selects any one of these shift maps according to the heat storage amount of each friction engagement element. The TCU 50 calculates the throttle opening Th of the engine 1 and the vehicle speed V (for example, calculation from the rotational speed N2 of the output shaft 38) based on a map selectively set according to the heat storage amount of each friction engagement element. Shift control using parameters is performed. Here, in the ROM 52 of the TCU 50, for example, the amount of heat generated during the engagement operation of the friction engagement element is calculated based on the relationship between the disk differential rotation speed of the friction engagement element and the input torque to the transmission 3. A heat release amount calculation map (for example, see FIG. 6) is stored, and a heat release amount calculation for calculating a heat release amount of the friction engagement element according to an elapsed time after the friction engagement element is fastened. Maps (not shown) are stored, and the TCU 50 calculates the heat storage amount for each friction engagement element using the heat generation amount and the heat release amount calculated from these maps. The map for calculating the heat generation amount and the heat release amount is set for each friction engagement element, and these maps are obtained in advance by experiments or the like, for example. That is, the TCU 50 realizes functions as a heat generation amount calculation unit, a heat release amount calculation unit, a heat storage amount calculation unit, and a shift timing setting unit.

  Next, the setting of the shift map executed by the TCU 50 will be described with reference to the flowchart shown in FIG. In this embodiment, the normal time shift map is set as a shift map used for automatic shift control in the TCU 50 in the initial state immediately after the ignition switch 60 is turned on. This routine is executed every set time. When the routine starts, the TCU 50 reads detection signals of various sensors and switches through the input interface 54 in step S101, and then proceeds to step S102.

  When the process proceeds from step S101 to step S102, the TCU 50 determines whether the current shift timing to the predetermined gear position is based on the throttle opening Th of the engine 1 and the vehicle speed V based on the currently set shift map. Find out.

  If it is determined in step S102 that the current shift timing to the predetermined shift speed is reached, the TCU 50 proceeds to step S103 and determines a friction engagement element that is engaged in the current shift.

  When the process proceeds from step S103 to step S104, the TCU 50 calculates disk differential rotation speed information (differential rotation speed information between the inner disk and the outer disk) of the friction engagement element that is engaged by the current shift, and in subsequent step S105. The input torque information to the transmission 3 is calculated. Here, in this embodiment, the disk differential rotation speed information is calculated based on, for example, the rotation speed N1 of the input shaft 9, the rotation speed N2 of the output shaft 38, the gear ratios of the planetary gear mechanisms 21 and 22, and the like. The input torque information of the transmission 3 is calculated based on, for example, the engine torque Te calculated by the ECU 70, the torque ratio tconv of the torque converter, and the like. The torque ratio tconv is obtained from a map set in advance based on, for example, the speed ratio rv (the rotational speed N1 of the input shaft 9 / the engine rotational speed Ne) of the torque converter 2.

  When the process proceeds from step S105 to step S106, the TCU 50 performs the fastening operation using the disc differential rotation speed information and the input torque information as parameters based on the calorific value calculation map corresponding to the friction engagement element that is engaged at the current shift. The calorific value Qr of the friction engagement element at the time is calculated. Here, generally, as the disc differential rotation speed of the friction engagement element and the input torque to the transmission 3 are increased, the engagement operation time of the friction engagement element is controlled to be longer. A large value is calculated for Qr.

  In the subsequent step S107, the TCU 50 uses the heat dissipation amount Qd of the other friction engagement elements (that is, the friction engagement elements other than the friction engagement elements that are fastened by the current shift) to the corresponding heat dissipation amount calculation maps. Then, the process proceeds to step S109.

  On the other hand, if it is determined in step S102 that the current shift timing to the predetermined gear position is not reached, the TCU 50 proceeds to step S108, and the heat release amount Qd of each friction engagement element is based on the corresponding heat release amount calculation map. Then, the process proceeds to step S109.

  When the process proceeds from step S107 or step S108 to step S109, the TCU 50 uses the heat generation amount Qr or the heat dissipation amount Qd of each frictional engagement element calculated in step S106, step S107, or step S108 to calculate the current heat storage amount Q. Is calculated for each friction engagement element. That is, the TCU 50 adds the heat generation amount Qr calculated in step S106 to the heat storage amount Q up to the previous time for the friction engagement elements that are engaged by the current shift, and the friction engagement elements that are not so until the previous time. The heat storage amount Q for each friction engagement element is updated by subtracting the heat release amount Qd calculated in step S107 or S108 from the heat storage amount Q. In this calculation, the TCU 50 sets the lower limit value Q2 of the heat storage amount Q based on the oil temperature T of the ATF detected by the oil temperature sensor 66, and the heat storage amount Q falls below the lower limit value Q2 by subtraction by the heat release amount Qd. In this case, the heat storage amount Q of the friction engagement element is corrected to the lower limit value Q2. By these calculations, the heat storage amount for each friction engagement element is calculated. Here, FIG. 7 shows an example of the transition of the heat storage amount Q of a certain friction engagement element calculated by the TCU 50. In FIG. 7, S1 to S4 indicate timings at which the friction engagement elements are engaged.

  When the process proceeds from step S109 to step S110, the TCU 50 checks whether or not the heat storage amount Q of each friction engagement element is equal to or less than a preset allowable value (set value) Q1. Here, the permissible value Q1 is predicted to cause a sufficient amount of heat to cause the frictional engagement element to avoid thermal damage such as burning (in other words, to cause thermal damage such as burning on the frictional engagement element). In this embodiment, the allowable value Q1 is set corresponding to each friction engagement element by an experiment or the like performed in advance.

  If it is determined in step S110 that all the heat storage amounts Q of the respective friction engagement elements are equal to or less than the corresponding allowable value Q1, the TCU 50 proceeds to step S111, and shifts the shift map used for the automatic shift control to the normal shift. After setting the map (see FIG. 5A), the routine is exited.

  On the other hand, if it is determined in step S110 that at least one of the heat storage amount Q of each friction engagement element is equal to or greater than the corresponding allowable value Q1, the TCU 50 proceeds to step S112 and sets a shift map used for automatic shift control. After setting the high temperature shift map (see FIG. 5B), the routine is exited. Thereby, the shift timing to each shift stage in the automatic shift control is set to a shift timing earlier than normal.

  According to such a configuration, when any of the calculated heat storage amounts Q of the respective friction engagement elements is higher than the allowable value Q1, the shift timing to each shift stage in the automatic shift control is changed faster than usual. By setting the timing, it is possible to suppress the heat generation amount during the fastening operation and protect the friction engagement element from heat damage. In other words, by advancing the shift timing, the disc differential rotation speed of the friction engagement element that engages during shifting can be reduced, and the amount of heat generated when the friction engagement element is engaged can be effectively suppressed. it can. Accordingly, the amount of heat stored in the friction engagement element can be suppressed even in a traveling state in which shifting to the same gear stage is frequently performed in a short time, such as when traveling on a continuous curved road, Each friction engagement element can be accurately protected from heat damage.

  At this time, the TCU 50 can easily calculate the heat generation amount Qr by calculation based on the disc differential rotation speed when the friction engagement element is engaged and the input torque of the transmission 3, and further, the transmission 3 By limiting the value of the heat storage amount Q by the lower limit value Q2 set based on the oil temperature T of the ATF inside, the heat storage amount Q of the friction engagement element during the non-engagement operation is prevented from being calculated too low The calculation accuracy of the heat storage amount Q can be improved.

  In the above-described embodiment, an example has been described in which when at least one of the heat storage amount Q of each friction engagement element becomes equal to or greater than the allowable value Q1, the shift timing to all the shift stages in the self-propelled shift control is advanced. However, the present invention is not limited to this, and, for example, it may be configured to individually advance only the shift timing of the shift stage using the friction engagement element in which the heat storage amount Q is equal to or greater than the allowable value Q1. In addition, in view of the fact that the amount of heat generated at the time of upshift is generally larger than that at the time of downshift, only the upshift timing to the gear stage using the friction engagement element whose heat storage amount Q is equal to or greater than the allowable value Q1 It is good also as a structure which speeds up individually.

Block diagram showing the entire control system of an automatic transmission Skeleton diagram showing outline of transmission Circuit diagram of transmission control device Flowchart of shift map setting routine Characteristic diagram of shift map Map showing the relationship between clutch differential speed and input torque Time chart showing an example of changes in calculated clutch heat storage

Explanation of symbols

3 ... Transmission 27 ... High clutch (friction engagement element)
31 ... Reverse clutch (friction engagement element)
32 ... 2 & 4 brake (friction engagement element)
36 ... Low and reverse brake (friction engagement element)
42 ... Low clutch (friction engagement element)
50 ... Transmission control device (heat generation amount calculation means, heat release amount calculation means, heat storage amount calculation means, shift timing setting means)
Q ... Amount of heat storage Q1 ... Allowable value (set value)
Q2 ... Lower limit value Qd ... Heat release amount Qr ... Heat release amount T ... Oil temperature
Agent Patent Attorney Susumu Ito

Claims (2)

In a shift control device for an automatic transmission that selectively controls a plurality of friction engagement elements to perform shift control of the transmission,
A calorific value calculation means for calculating a calorific value of each of the friction engagement elements that are engaged among the plurality of friction engagement elements during a shift operation of the automatic transmission;
Each of the plurality of friction engagement elements is calculated during a non-shifting operation of the automatic transmission by calculating a heat release amount of each of the plurality of friction engagement elements that is not engaged during the shifting operation of the automatic transmission. A heat dissipation amount calculating means for calculating the heat dissipation amount of
A heat storage amount calculation means for cumulatively calculating a heat storage amount for each friction engagement element based on the heat generation amount calculated by the heat generation amount calculation means and the heat dissipation amount calculated by the heat dissipation amount calculation means;
When there is the friction engagement element having a heat storage amount calculated by the heat storage amount calculating means equal to or greater than a set value, at least the upshift timing to the gear position using the friction engagement element having a heat storage amount equal to or greater than the set value. Shift timing setting means for setting the timing earlier than when the heat storage amount is less than or equal to the set value ,
The heat storage amount calculation means sets a lower limit value based on the oil temperature of the hydraulic oil in the transmission, and corrects the heat storage amount to the lower limit value when the heat storage amount falls below the lower limit value. A shift control device for an automatic transmission characterized by the above.   The calorific value calculation means calculates the calorific value based on a disc differential rotation speed of the friction engagement element when the friction engagement element is engaged and an input torque of the transmission. The shift control device for an automatic transmission according to claim 1.

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