JP2010101264A - Automatic transmission control unit and method for limiting output - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic transmission control unit or the like, which carries out, under only suitable conditions, an output restriction in the event of the abnormality of the temperature sensor. <P>SOLUTION: The automatic transmission control unit 19 for restricting the output of an engine 11 when the temperature detected by a temperature sensor 22 is a predetermined value or more, has: a maximum temperature storing means 23 for storing the maximum value of temperatures detected in the past by the temperature sensor; a temperature sensor abnormality detection means 32 for detecting abnormality in the temperature sensor; a past temperature determination means 35 for determining whether the maximum temperature is not higher than a determination temperature previously stored; an operation determination means 36 for determining whether the application of both an acceleration pedal and a brake pedal has been continued for within a predetermined time period when the abnormality of the temperature sensor has been detected; and an output restricting means 37 which does not restrict the output of the engine 11 when the maximum temperature is not higher than a determination temperature previously stored and the application of both the acceleration pedal and the brake pedal has been continued for within a predetermined time period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automatic transmission control unit that limits engine output when a temperature detected by a temperature sensor reaches a predetermined value or more, and more particularly to an automatic transmission capable of fail-safe when an abnormality occurs in a temperature sensor. The present invention relates to a control unit and an output limiting method.

  In some cases, the electronic control unit of the automatic transmission is arranged in the housing of the automatic transmission, that is, in a state exposed to transmission oil, due to restrictions on the in-vehicle space and wiring. The temperature of the transmission oil is designed not to exceed the rated temperature in general vehicle operation, but if there is a vehicle operation that overloads the transmission oil, the transmission oil is emitted by the automatic transmission. The temperature rises due to heat. As a result, the electronic control unit may receive heat from the transmission oil and exceed the rated temperature. For this reason, it is considered that a temperature sensor is built in the electronic control device, and when the temperature of the electronic control device becomes equal to or higher than a predetermined value, control for preventing the temperature rise of the transmission oil is executed (for example, patent document). 1). Patent Document 1 discloses a cooling method for an automatic transmission that lowers the temperature of transmission oil by forcibly engaging a lockup clutch, reducing the pressure regulation value of a pressure regulator, etc., when the temperature of the electronic control unit exceeds a predetermined value. Has been.

Also, an electronic control that predicts a temperature increase of the transmission oil that correlates with the temperature of the electronic control device, and stops the power supply to the electronic control device when the temperature of the transmission oil is predicted to exceed a predetermined temperature. An apparatus has also been proposed (see, for example, Patent Document 2). Since power supply to the electronic control device is stopped, self-heating of the electronic control device can be suppressed.
JP 2004-125028 A Japanese Patent Laid-Open No. 10-166965

  However, when an abnormality occurs in the temperature sensor installed in the electronic control device, the electronic control device described in Patent Documents 1 and 2 may not be able to suppress the temperature rise. Therefore, if an abnormality occurs in the temperature sensor of the electronic control unit, by limiting the output of the automatic transmission, even if the temperature cannot be detected, the output is limited so that the rated temperature is not exceeded, thereby achieving fail safe. Many.

  However, since the electronic control unit is designed not to exceed the rated temperature during general vehicle operation, it is not possible to limit the output uniformly when an abnormality occurs in the temperature sensor. There is a problem that the output is limited even in the range, which affects drivability.

  In view of the above problems, an object of the present invention is to provide an automatic transmission control unit and an output limiting method capable of suppressing a decrease in drivability due to output limitation when an abnormality occurs in a temperature sensor.

  In view of the above problems, the present invention is an automatic transmission control unit that is disposed in a transmission case and limits the output of an engine when a temperature detected by a temperature sensor provided integrally exceeds a predetermined value. The maximum temperature storage means for storing the maximum temperature among the detected temperatures, the temperature sensor abnormality detection means for detecting an abnormality of the temperature sensor, and the determination that the maximum temperature is stored in advance when an abnormality of the temperature sensor is detected Past temperature determination means for determining whether or not the temperature is equal to or lower than the operating temperature, and operation determination means for determining whether or not the state where both the accelerator pedal and the brake pedal are depressed is within a predetermined time when abnormality of the temperature sensor is detected. If the maximum temperature is equal to or lower than the pre-stored judgment temperature and the accelerator pedal and the brake pedal are both depressed within a predetermined time, the engine output And not limit output limiting means, characterized by having a.

  It is possible to provide an automatic transmission control unit and an output limiting method for executing output limitation only in an appropriate situation when an abnormality occurs in a temperature sensor.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1A is a schematic configuration diagram of the power train, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. The illustrated power train is of a type called an automatic transmission. The automatic transmission has an engine 11 rotation speed so that the engine output can be optimized and transmitted to the drive wheels according to the driving conditions such as torque curve and acceleration / deceleration. Change the speed. The hardware configuration is publicly known, and the transmission to which the electronic control device of this embodiment is applied is not limited.

  The transmission 12 includes a torque converter 13 that is a fluid clutch, an automatic transmission 14 that changes a gear ratio by switching a coupling mode of a plurality of gears, a flow path of transmission oil, an oil pressure, and the like by controlling opening and closing of a plurality of valves. A valve body 18 that controls the transmission, an oil cooler 15 that cools the transmission oil, an oil van 20 that stores excess transmission oil, and a transmission ECU (Electronic Control Unit: electronic) that controls the opening and closing of the valve of the valve body 18 Control unit) 19. A temperature sensor, which will be described later, is disposed in the transmission ECU 19.

  The transmission 12 includes a pump mechanism for generating hydraulic pressure in the transmission oil. There are pump mechanisms that utilize the rotation of the engine 11 and those that are driven by an electric motor. In either case, the oil that has been filtered from the oil van 20 through the strainer 17 is sucked up. This oil is pressure-regulated by a pressure regulator, a part is supplied to the torque converter 13 and used for torque transmission, and a part is supplied to the valve body 18 to control the gear connection mode of the automatic transmission 14 and to lock-up fastening. Used for.

  The rotational torque at which the engine 11 rotates the crankshaft is transmitted to the input side (pump impeller) of the torque converter 13 and rotates the output side (turbine liner) of the torque converter 13. This torque rotationally drives the input shaft of the automatic transmission 14, and torque according to the gear coupling mode determined by the gear ratio and rotation direction is transmitted to the output shaft of the automatic transmission 14. The torque output from the automatic transmission 14 rotates the propeller shaft 16 and rotates the drive shaft and drive wheels via the differential gear. The automatic transmission 14 combines an internal gear and a plurality of external gears, so that there are three peripheral gears: a peripheral external gear (pinion gear), a central external gear (sun gear), and an internal gear. It has a rotation axis and selectively determines the presence / absence and direction of rotation of each. Therefore, the gear ratio can be changed in three stages by one automatic transmission 14 (and the reverse gear is 1st). In many cases, another transmission is connected to the rear stage so that the transmission can be shifted to four or more stages.

  The valve body 18 is mounted with a plurality of shift solenoid valves, line pressure solenoid valves, lock-up solenoid valves, etc. that are integrated with various solenoids. Controls the distribution of machine oil. Hereinafter, solenoids and solenoid valves are not distinguished. When the shift solenoid valve is turned on, the corresponding valve is opened and closed to change the gear coupling mode. When the lockup solenoid is turned on, the lockup clutch is engaged. Further, the line pressure solenoid valve adjusts the opening of the valve so that the pressure regulation value of the pressure regulator that regulates the oil pressure of the oil pump becomes constant according to the energization amount. Transmission oil discharged from the valve body 18 by opening and closing the valve is cooled by the oil cooler 15 and then circulates to the oil van 20.

  The transmission ECU 19 is wetted by transmission oil stored in the oil van 20 while being fixed to the valve body 18, for example. That is, the transmission ECU 19 is constantly fixed at a position lower than the level of the transmission oil, and the transmission oil and the transmission ECU 19 exchange heat with each other. In a general driving state, the temperature of the transmission oil is lower than the temperature of the transmission ECU 19, and the transmission ECU 19 is cooled by the transmission oil.

  FIG. 2 shows an example of a schematic configuration diagram of the transmission ECU 19. In the transmission ECU 19, a microcomputer 21 that controls the entire transmission 12 on the board, a temperature sensor 22 that detects the temperature of the transmission ECU 19, and an EEPROM (Electrically Erasable and Programmable Read) that stores the past maximum temperature. Only Memory) 23 and the like are connected. In addition, an in-vehicle LAN interface such as CAN (Controller Area Network) and FlexRay for communicating with other ECUs such as an engine ECU, a nonvolatile memory storing programs and various parameters, and the like are provided. For example, the substrate is made of glass epoxy (glass fiber hardened with epoxy resin) with copper foil connections, but a one-chip microcomputer composed entirely of one IC, chip-on with multiple chips connected directly A chip or the like may be used. The transmission ECU 19 is provided with a connection terminal to the valve body 18, connection terminals with various sensors, a connection terminal to the in-vehicle LAN, and the like. These terminals are connected to an input / output interface of the microcomputer 21. ing.

  FIG. 3 is an example of a diagram for schematically explaining the input and output to the microcomputer 21. The microcomputer 21 includes a CPU that executes a program stored in a nonvolatile memory (not shown) in a working memory, an ASIC (Application Specific Integrated Circuit) that is mounted in correspondence with a specific calculation and control, and a MOSFET that energizes various solenoids. And a computer in which switch elements such as IGBTs (Insulated Gate Bipolar Transistors) are connected via an internal bus.

  The microcomputer 21 has a plurality of input / output interfaces for acquiring signals from various sensors including the temperature sensor 22 and for energizing various solenoids, adjusting the opening degree, accessing the EEPROM 23, and the like. The microcomputer 21 performs A / D conversion on the detection signal of the sensor, executes various calculations, and outputs the execution result after D / A conversion if necessary.

  For example, information input to the microcomputer 21 includes an accelerator opening that is an operation amount of a driver's accelerator pedal, an on / off state of a brake SW (switch) that detects a brake pedal operation, a temperature detected by the temperature sensor 22, There are a past maximum temperature (EEPROM), vehicle speed information, the rotational speed of the automatic transmission 14, a shift position that is an operation position of the shift lever by the driver, and the like. The information output from the microcomputer 21 includes a request for lighting a temperature warning light indicating that the temperature of the transmission ECU 19 is equal to or higher than a predetermined value, a sensor warning light indicating that the temperature sensor 22 is abnormal, an engine There are communication information with the ECU, a maximum temperature for updating (EEPROM), energization of various solenoids, control signals for controlling valve openings, and the like. Note that either the input side or the output side may be acquired directly from a sensor, solenoid, or actuator, or may be acquired via another ECU.

  For example, the microcomputer 21 specifies a range of shift speeds that can be selected according to the shift position, and determines a target shift speed with reference to a two-dimensional map in which the speed ratio is associated with the vehicle speed or the accelerator opening. Then, by energizing a solenoid corresponding to the target shift speed, the gear transmission mode of the automatic transmission 14 is connected and disconnected so that a desired gear ratio is obtained.

  Further, when the temperature detected by the temperature sensor 22 exceeds a predetermined value, the microcomputer 21 requests, for example, the meter ECU to turn on a warning lamp, and notifies the driver that the transmission oil is hot. As is well known, the torque converter 13 in a state where the lock-up clutch is not engaged transmits the torque of the engine 11 to the automatic transmission 14 using the kinetic energy of the transmission oil as a medium. For this reason, the transmission oil generates heat due to viscosity, and the temperature rises. In particular, a high torque is required when climbing, and the engine speed is high and the speed of the automatic transmission 14 is low, so heat generation increases. However, in the heat generation of the transmission oil due to such an assumed traveling situation, the cooling capacity of the oil cooler 15 so that the temperature of the transmission oil is suppressed to a certain temperature or less (for example, the rated temperature of the transmission ECU 19 or less). And heat capacity is designed.

  Further, if the temperature approaches the rated temperature, the microcomputer 21 executes control to reduce the temperature of the transmission oil. For example, the engine speed is limited or the output of a pump that generates hydraulic pressure is reduced (hereinafter, these are simply referred to as output limitation). Moreover, when the cooling fan is attached to the oil cooler 15, you may raise the rotation speed of a cooling fan.

  However, in irregular usage that is difficult to imagine, the temperature of the transmission oil may exceed the rated temperature. For example, this is a case where a state where the accelerator pedal is continuously depressed for a long time while the brake pedal is depressed. In this case, the turbine liner does not rotate, and most of the kinetic energy of the transmission oil generated by the pump impeller by the rotation of the engine 11 is converted into heat.

  Even if the temperature sensor 22 is normal even if it generates heat and approaches the rated temperature, the above output limitation may be executed. However, if the temperature sensor 22 is not normal, it is difficult to determine whether output restriction is necessary in the first place. Therefore, if the temperature sensor 22 fails from the viewpoint of fail-safety, output restriction may be performed regardless of the actual temperature. Conceivable. However, since the temperature of the transmission oil is designed not to exceed the rated temperature, drivability is impaired if the output is uniformly limited just because the temperature sensor 22 has failed. Therefore, the transmission ECU 19 of this embodiment limits the output only when the transmission oil may actually exceed the rated temperature.

FIG. 4 shows an example of a functional block diagram of the microcomputer 21. Each functional block is realized by a CPU of the microcomputer 21 executing a program or hardware such as an ASIC. In order to determine whether or not the transmission oil may exceed the rated temperature when the temperature sensor 22 fails, the microcomputer 21 uses two pieces of information.
1) Past maximum temperature of ECU 19 for transmission 2) Accelerator opening, on / off of brake SW The past maximum temperature is used because the user used the accelerator pedal and brake pedal in an irregular manner. This is to determine whether or not there is. As long as the user does not operate the gearbox ECU in an irregular manner, the maximum temperature in the past will exceed the rated temperature if the user operates the accelerator and brakes in the assumed manner of use. It is not considered. Therefore, if the past maximum temperature is sufficiently lower than the rated temperature, it is unlikely that the rated temperature will be exceeded while the temperature sensor 22 is malfunctioning. In the present embodiment, if the past maximum temperature is equal to or lower than the usage mode determination temperature 34 that allows for a margin in the rated temperature, the user determines that the accelerator operation and the brake operation are performed in the assumed usage mode.

  Further, the accelerator opening degree and the brake SW on / off state are used to determine whether or not the current usage state is the state in which the temperature of the transmission ECU 19 is most likely to rise. As described above, it is considered that the temperature is most likely to rise when the accelerator pedal and the brake pedal are depressed simultaneously. This state occurs regardless of the past maximum temperature, and even if the past maximum temperature is equal to or lower than the usage mode determination temperature 34, the maximum temperature may be updated. Used for The presence or absence of depression of the brake pedal may be determined from the master cylinder pressure, the brake pedal stroke sensor, or the like.

  Based on the above concept, the functional block diagram of FIG. 4 will be described. First, the maximum temperature update unit 31 updates the past maximum temperature stored in the EEPROM 23. The maximum temperature update unit 31 reads the past temperature stored in the EEPROM 23 and compares it with the temperature detected by the temperature sensor 22. As a result of the comparison, if the temperature detected by the temperature sensor 22 is higher, the past maximum temperature of the EEPROM 23 is replaced with the temperature detected by the temperature sensor 22 (maximum temperature for update). Therefore, the past maximum temperature is always stored in the EEPROM 23. Instead of storing only one past maximum temperature, a predetermined number (for example, three) of temperatures including the maximum temperature may be stored in descending order. Comparing the usage mode determination temperature 34 with the lowest temperature among the plurality of temperatures instead of the maximum temperature makes it easier to prevent the rated temperature from being exceeded during the failure of the temperature sensor 22. Further, if the average of a plurality of temperatures is compared with the usage mode determination temperature 34, the output is limited when the past maximum temperature is a temperature detected in a situation different from the normal usage mode for the user. Can be suppressed. Further, for example, in order to eliminate a past maximum temperature due to an erroneous operation, a past maximum temperature that is older than a predetermined period (not updated) may be deleted.

  And the temperature sensor abnormality determination part 32 determines whether the temperature sensor 22 failed. There are various failure determination methods. For example, when the microcomputer 21 and the temperature sensor are disconnected, the voltage value input to the microcomputer 21 becomes zero. Is detected because the temperature input to the microcomputer 21 exceeds the upper limit or the lower limit. Further, the temperature sensor 22 itself is also provided with a failure detection circuit, and detects abnormalities in the relationship between the internal voltage, resistance and temperature caused by disconnection / short circuit inside the temperature sensor, and notifies the microcomputer 21 of them. When an abnormality of the temperature sensor 22 is detected, the sensor abnormality warning unit 33 requests the meter ECU to turn on a sensor warning lamp that notifies the temperature sensor 22 that there is an abnormality.

  When an abnormality of the temperature sensor 22 is detected, the past temperature determination unit 35 reads the past maximum temperature stored in the EEPROM 23 and compares it with the use mode determination temperature 34 stored in advance. When the past maximum temperature is higher, it is determined that the past usage mode is outside the assumed range, that is, the temperature of the transmission ECU 19 may exceed the rated temperature.

  In addition, the operation determination unit 36 determines whether or not the simultaneous depression of both the accelerator opening degree and the brake SW on / off has continued for a predetermined time or more. When the simultaneous depression continues for a predetermined time, it is determined that the temperature of the transmission ECU 19 may exceed the rated temperature.

  Then, the output limiting unit 37 determines the temperature of the transmission ECU 19 when there is a possibility that the temperature of the transmission ECU 19 actually exceeds the rated temperature, or from the past maximum temperature or the operation state of the accelerator pedal and the brake pedal. If there is a possibility that will exceed the rated temperature, limit the engine power. Further, the high temperature warning unit 38 requests the meter ECU to turn on a temperature warning lamp for notifying that the temperature of the transmission ECU 19 is high.

  FIG. 5 is an example of a flowchart illustrating a procedure in which the transmission ECU 19 limits the output when the temperature sensor 22 is abnormal. The flowchart in FIG. 5 is repeatedly executed at predetermined cycle times when the ignition is turned on.

  The temperature sensor abnormality determination unit 32 acquires the temperature of the transmission ECU 19 detected by the temperature sensor 22, and determines whether or not the temperature sensor 22 is normal (S10).

  When the temperature sensor 22 is normal (Yes in S10), the maximum temperature update unit 31 updates the past maximum temperature stored in the EEPROM 23, so the temperature detected by the temperature sensor 22 is stored in the EEPROM 23. It is determined whether or not the temperature is higher than the maximum temperature (S50). When the temperature detected by the temperature sensor 22 is higher than the past maximum temperature stored in the EEPROM 23 (Yes in S50), the maximum temperature update unit 31 replaces the past maximum temperature of the EEPROM 23 with the temperature detected by the temperature sensor 22. (S60).

  On the other hand, the output restriction unit 37 determines whether or not the temperature detected by the temperature sensor 22 is equal to or higher than a predetermined value (S70). Since the output is limited when the value is equal to or greater than the predetermined value, the predetermined value is set slightly lower than the rated temperature.

  When the temperature detected by the temperature sensor 22 is equal to or higher than a predetermined value (Yes in S70), the output restriction unit 37 restricts the output of the engine 11, and the high temperature warning unit 38 requests the meter ECU to turn on the temperature warning light. (S80). If the temperature detected by the temperature sensor 22 is not equal to or higher than the predetermined value (No in S70), the microcomputer 21 repeats the process from step S10.

  Returning to step S10, if the temperature sensor 22 is not normal (No in S10), the past temperature determination unit 35 determines whether or not the past maximum temperature stored in the EEPROM 23 is equal to or lower than the use mode determination temperature 34 (S20). ). If the past maximum temperature is not lower than the usage mode determination temperature 34 (No in S20), the driver of the vehicle may operate the accelerator pedal and the brake pedal in an irregular usage mode. 11, the high temperature warning unit 38 requests the meter ECU to turn on the temperature warning lamp (S80).

  When the past maximum temperature is equal to or lower than the usage mode determination temperature 34 (Yes in S20), the operation determination unit 36 determines whether or not the simultaneous depression of the accelerator pedal and the brake pedal is within a predetermined time (S30). If the simultaneous depression of the accelerator pedal and the brake pedal is not within the predetermined time (No in S30), the temperature of the transmission ECU 19 may exceed the rated temperature, so the output limiting unit 37 limits the output of the engine 11, The high temperature warning unit 38 requests the meter ECU to turn on the temperature warning lamp (S80).

  If the simultaneous depression of the accelerator pedal and the brake pedal is within a predetermined time (Yes in S30), the sensor abnormality warning unit turns on the sensor warning lamp without limiting the output (S40).

  As described above, the transmission ECU 19 according to the present embodiment has a past maximum temperature of the use mode determination temperature 34 or lower (Yes in S20), and the simultaneous depression of the accelerator pedal and the brake pedal is within a predetermined time ( Since the output is not limited at S30, it is not necessary to immediately limit the output even if the temperature sensor 22 is not normal, and it is possible to suppress a decrease in drivability.

It is an example of the schematic block diagram of a power train. It is an example of the schematic block diagram of ECU for transmission. It is an example of the figure which illustrates the input and output to a microcomputer typically. It is an example of the functional block diagram of a microcomputer. It is an example of the flowchart figure which shows the procedure in which ECU for transmissions carries out an output limitation at the time of abnormality of a temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Engine 12 Transmission 13 Torque converter 14 Automatic transmission 15 Oil cooler 18 Valve body 19 ECU for transmission
21 Microcomputer 22 Temperature sensor 23 EEPROM

Claims (2)

A control unit for an automatic transmission that is disposed in a transmission case and limits the output of the engine when the temperature detected by a temperature sensor provided integrally becomes a predetermined value or more,
Maximum temperature storage means for storing the maximum temperature among the temperatures detected by the temperature sensor in the past;
Temperature sensor abnormality detecting means for detecting abnormality of the temperature sensor;
Past temperature determination means for determining whether or not the maximum temperature is equal to or lower than a pre-stored determination temperature when an abnormality of the temperature sensor is detected;
When an abnormality of the temperature sensor is detected, an operation determination means for determining whether or not the state where both the accelerator pedal and the brake pedal are depressed is within a predetermined time;
When the maximum temperature is equal to or lower than a preliminarily stored determination temperature, and the state where both the accelerator pedal and the brake pedal are depressed is within a predetermined time, output limiting means that does not limit the output of the engine;
A control unit for an automatic transmission, comprising: An output limiting method for limiting the output of the engine when a temperature detected by a temperature sensor disposed in the transmission case and integrated with the temperature sensor exceeds a predetermined value,
Storing the highest temperature among the temperatures detected by the temperature sensor in the past;
Detecting an abnormality of the temperature sensor;
When an abnormality of the temperature sensor is detected, determining whether the maximum temperature is equal to or lower than a pre-stored determination temperature;
Determining whether the state where both the accelerator pedal and the brake pedal are depressed is within a predetermined time when an abnormality of the temperature sensor is detected, and
When the maximum temperature is equal to or lower than a pre-stored determination temperature and the state where both the accelerator pedal and the brake pedal are depressed is within a predetermined time, the engine output is not limited.
An output limiting method characterized by that.

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