Abnormal Detection Device for Lockup Clutch

Abstract

To provide an abnormality detection device of a lock-up clutch capable of increasing a diagnosis frequency for abnormal fastening and fixing of the lock-up clutch in a torque converter while preventing wrong detection.SOLUTION: A transmission control unit (TCU) 40 is configured to: when a shift range of a continuously variable transmission 20 is switched from a parking (P) range or neutral (N) range to a forward travel (D) range or reverse travel (R) range, and when a vehicle decelerates to a stop, count the number of times when a turbine speed and an engine speed intersect (the number of times when the vertical relation is switched); and when the number of times (count value) is equal to or larger than a preset number of times, determine that abnormal fastening and fixing occurs in a lock-up clutch 25.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an abnormal detection device for a lock-up clutch of a torque converter, and more particularly to an abnormal detection device for a lock-up clutch that detects an abnormal fastening and sticking of the lock-up clutch.

Background Art

[0002] Conventionally, a torque converter that uses a fluid (oil) to amplify engine torque (engine driving force) in combination with a stepped automatic transmission (step AT), a continuously variable transmission (CVT), etc. mounted on a vehicle has been widely used. Since the torque converter transmits engine torque via oil and has a torque amplification function, it enables smooth vehicle start. In addition, the torque converter also has a function of absorbing vibrations generated from the engine. On the other hand, in a torque converter, since engine torque is transmitted via oil, transmission loss due to slippage occurs (that is, transmission efficiency decreases).

[0003] In order to suppress such a decrease in transmission efficiency due to the torque converter and improve the fuel consumption rate (fuel efficiency), for example, a lock-up mechanism (lock-up clutch) that directly connects the input (engine crankshaft) and the output (input shaft of the transmission) at a predetermined vehicle speed or higher has been widely adopted. That is, at the time of starting, when the lock-up clutch is released, the amplified engine torque is input to the input shaft of the transmission via the torque converter. On the other hand, for example, at the time of steady running, when the lock-up clutch is engaged, engine torque is directly input from the crankshaft of the engine to the input shaft of the transmission.

[0004] By the way, when such a lock-up clutch becomes stuck in the engaged state, for example, the engine may stall when the vehicle stops. Therefore, as a technique for detecting the fastening and sticking of the lock-up clutch, for example, Patent Document 1 discloses a control device for an automatic transmission for a vehicle that can detect an on-stack failure of an LC pressure control linear solenoid at the time of starting the vehicle.

[0005] More specifically, in this device, when the vehicle starts, the detection execution timer T is activated when the actual torque converter slip ratio ETR1 exceeds the first threshold value U1, and within the set time ΔT1 of the detection execution timer T, when the actual torque converter slip ratio ETR1 falls below the second threshold value L1, the LC pressure control linear solenoid is determined to have an on-stack failure, and the count number of the failure detection counter FC is incremented. Then, when the count number of the failure detection counter FC exceeds the NG threshold value, the on-stack failure of the LC pressure control linear solenoid is confirmed, and a fail-safe action is performed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, in the technology disclosed in Patent Document 1, a diagnosis is made as to whether the lock-up clutch is engaged and fixed when the vehicle starts. Therefore, for example, when the lock-up clutch engages and fixes during running, the vehicle stops, and the abnormality cannot be detected until the vehicle starts again. Therefore, there has been a desire to increase the diagnosis frequency of the lock-up clutch engagement and fixation abnormality while preventing false detection and detect the engagement and fixation abnormality more quickly.

[0008] The present invention has been made to solve the above problems, and an object thereof is to provide an abnormality detection device for a lock-up clutch that can increase the diagnosis frequency of the engagement and fixation abnormality of the lock-up clutch in a torque converter while preventing false detection.

Means for Solving the Problems

[0009] The lock-up clutch abnormality detection device according to the present invention includes a turbine rotation speed detection means for detecting the rotation speed of a turbine of a torque converter interposed between an engine and an automatic transmission, an engine rotation speed detection means for detecting the rotation speed of the engine, and a control unit for controlling the engagement and release of the lock-up clutch of the torque converter. When the control unit switches the shift range of the automatic transmission from the parking range or neutral range to the forward driving range or reverse driving range, and when the vehicle decelerates and stops, the control unit counts the number of times the turbine rotation speed and the engine rotation speed cross each other. When the number of times reaches a predetermined number or more, it is determined that there is an abnormal engagement and fixation of the lock-up clutch.

[0010] According to the lock-up clutch abnormality detection device of the present invention, when the shift range of the automatic transmission is switched from the parking range or neutral range to the forward driving range or reverse driving range, an abnormal engagement and fixation of the lock-up clutch can be detected. That is, it is possible to detect abnormalities in the stopped state. Also, when the vehicle decelerates and stops, an abnormal engagement and fixation of the lock-up clutch can be detected, and the detection frequency (diagnosis frequency) can be increased. On the other hand, according to the lock-up clutch abnormality detection device of the present invention, the number of times the turbine rotation speed and the engine rotation speed cross each other (the number of times the vertical relationship is reversed) is counted. When the number of times reaches a predetermined number or more, it is determined that there is an abnormal engagement and fixation of the lock-up clutch. Therefore, it is possible to more accurately detect an abnormal engagement and fixation of the lock-up clutch.

Effects of the Invention

[0011] As a result, according to the present invention, it is possible to increase the diagnosis frequency of the on-fixation abnormality (abnormal engagement and fixation) of the lock-up clutch in the torque converter while preventing false detection.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. Also, in each figure, the same elements will be denoted by the same reference numerals and redundant explanations will be omitted.

[0014] First, with reference to FIG. 1, the configuration of the abnormality detection device 1 of the lock-up clutch according to the embodiment will be described. FIG. 1 is a block diagram showing the configuration of the abnormality detection device 1 of the lock-up clutch.

[0015] The engine 10 may be of any type. For example, it is a horizontally opposed in-cylinder injection type four-cylinder gasoline engine. In the engine 10, the air inhaled from an air cleaner (not shown) is throttled by an electronically controlled throttle valve (hereinafter simply referred to as "throttle valve") 13 provided in the intake pipe, passes through the intake manifold, and is inhaled into each cylinder formed in the engine 10. Here, the amount of air inhaled from the air cleaner is detected by an air flow meter. Further, a throttle opening sensor 14 for detecting the opening degree of the throttle valve 13 is disposed on the throttle valve 13. An injector for injecting fuel is attached to each cylinder. Further, a spark plug for igniting the air-fuel mixture and an in-igniter coil for applying a high voltage to the spark plug are attached to each cylinder. In each cylinder of the engine 10, the air-fuel mixture of the inhaled air and the fuel injected by the injector is ignited by the spark plug and burns. The exhaust gas after combustion is discharged through the exhaust pipe.

[0016] In addition to the above-described air flow meter and throttle opening sensor 14, a cam angle sensor for discriminating the cylinders of the engine 10 is attached near the camshaft of the engine 10. Further, a crank angle sensor 61 for detecting the rotational position of the crankshaft 15 is attached near the crankshaft 15 of the engine 10. These sensors are connected to an engine control unit (hereinafter referred to as "ECU") 60 described later. Further, various sensors such as an accelerator pedal sensor 62 for detecting the depression amount of the accelerator pedal, that is, the opening degree of the accelerator pedal, and a water temperature sensor for detecting the temperature of the cooling water of the engine 10 are also connected to the ECU 60.

[0017] A continuously variable transmission 20 that converts and outputs the driving force from the engine 10 is connected to the crankshaft (output shaft) 15 of the engine 10 via a torque converter 21 having a clutch function and a torque amplification function and a forward / reverse switching mechanism 27.

[0018] The torque converter 21 mainly consists of a pump impeller 22, a turbine runner 23, and a stator 24. The pump impeller 22 connected to the crankshaft 15 generates an oil flow, and the turbine runner 23 arranged opposite to the pump impeller 22 receives the power of the engine 10 through the oil and drives the output shaft. The stator 24 located between the two rectifies the discharge flow (return) from the turbine runner 23 and returns it to the pump impeller 22 to generate a torque amplification effect.

[0019] Also, the torque converter 21 has a lock-up clutch 25 that directly connects the input and output. When the lock-up clutch 25 is not engaged (in the non-lock-up state), the torque converter 21 amplifies the driving force of the engine 10 and transmits it to the continuously variable transmission 20. When the lock-up clutch 25 is engaged (during lock-up), the driving force of the engine 10 is directly transmitted to the continuously variable transmission 20.

[0020] Here, the engagement and release of the lock-up clutch 25 are performed by adjusting the hydraulic pressure (lock-up apply pressure) supplied to the lock-up clutch 25 (apply chamber). This lock-up apply pressure is controlled by a transmission control unit (hereinafter referred to as "TCU") 40. Also, the rotational speed of the turbine runner 23 that constitutes the torque converter 21 (turbine rotational speed) is detected by a turbine rotational speed sensor 56. The detected turbine rotational speed is output to the TCU 40. The turbine rotational speed sensor 56 functions as the turbine rotational speed detection means described in the claims.

[0021] The forward and reverse switching mechanism 27 switches between the forward rotation and reverse rotation of the drive wheels (the forward and reverse of the vehicle). The forward and reverse switching mechanism 27 mainly includes a double pinion type planetary gear train 28, a forward clutch 29, and a reverse brake 30. In the forward and reverse switching mechanism 27, the transmission path of the engine driving force can be switched by controlling the states of the forward clutch 29 and the reverse brake 30 respectively.

[0022] More specifically, by engaging the forward clutch 29 and releasing the reverse brake 30, the rotation of the turbine shaft 26 is directly transmitted to the primary shaft 32 described later, enabling the vehicle to move forward. Also, by releasing the forward clutch 29 and engaging the reverse brake 30, the planetary gear train 28 can be actuated to reverse the rotation direction of the primary shaft 32, enabling the vehicle to move backward. Note that by releasing the forward clutch 29 and the reverse brake 30, the turbine shaft 26 and the primary shaft 32 are disengaged, and the forward and reverse switching mechanism 27 is in a neutral state where it does not transmit power to the primary shaft 32. Note that the operations of the forward clutch 29 and the reverse brake 30 are controlled by the TCU 40 and the valve body (control valve) 50.

[0023] The continuously variable transmission 20 has a primary shaft 32 connected to the turbine shaft (output shaft) 26 of the torque converter 21 via the forward and reverse switching mechanism 27, and a secondary shaft 37 disposed parallel to the primary shaft 32.

[0024] The primary shaft 32 is provided with a primary pulley 34. The primary pulley 34 has a fixed sheave 34a joined to the primary shaft 32 and a movable sheave 34b mounted slidably in the axial direction of the primary shaft 32 opposite to the fixed sheave 34a, and is configured such that the cone surface interval between the respective sheaves 34a, 34b, that is, the pulley groove width, can be changed. On the other hand, the secondary shaft 37 is provided with a secondary pulley 35. The secondary pulley 35 has a fixed sheave 35a joined to the secondary shaft 37 and a movable sheave 35b mounted slidably in the axial direction of the secondary shaft 37 opposite to the fixed sheave 35a, and is configured such that the pulley groove width can be changed.

[0025] A chain 36 for transmitting driving force is stretched between a primary pulley 34 and a secondary pulley 35. By changing the groove widths of the primary pulley 34 and the secondary pulley 35 to change the ratio of the winding diameters of the chain 36 with respect to the respective pulleys 34, 35 (pulley ratio), the transmission ratio is steplessly changed. Here, if the winding diameter of the chain 36 with respect to the primary pulley 34 is Rp and the winding diameter with respect to the secondary pulley 35 is Rs, the transmission ratio i is represented by i = Rs / Rp. Therefore, the transmission ratio i is obtained by dividing the primary pulley rotation speed Np by the secondary pulley rotation speed Ns (i = Np / Ns).

[0026] Here, a hydraulic chamber 34c is formed in the primary pulley 34 (movable sheave 34b). On the other hand, a hydraulic chamber 35c is formed in the secondary pulley 35 (movable sheave 35b). The groove widths of the primary pulley 34 and the secondary pulley 35 are set and changed by adjusting the primary hydraulic pressure introduced into the hydraulic chamber 34c of the primary pulley 34 and the secondary hydraulic pressure introduced into the hydraulic chamber 35c of the secondary pulley 35.

[0027] The hydraulic pressure for shifting the continuously variable transmission 20, that is, the above-described primary hydraulic pressure and secondary hydraulic pressure, is controlled by a valve body (control valve) 50. The valve body 50 adjusts the hydraulic pressure discharged from an oil pump (not shown) by opening and closing an oil passage formed in the valve body 50 using a spool valve and a solenoid valve (electromagnetic valve) that moves the spool valve, and supplies it to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35. Further, the valve body 50 also supplies hydraulic pressure to a lock-up clutch 25, a forward / reverse switching mechanism 27, and the like.

[0028] The shift control of the continuously variable transmission 20 is executed by the TCU 40. That is, the TCU 40 controls the driving of the solenoid valves (electromagnetic valves) that make up the valve body 50 described above, adjusts the hydraulic pressure supplied to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35, and changes the transmission ratio of the continuously variable transmission 20. Further, the TCU 40 adjusts the amount of ATF (Automatic Transmission Fluid) supplied to and discharged from the forward clutch 29 to engage and disengage the forward clutch 29. Similarly, the TCU 40 adjusts the amount of ATF supplied to and discharged from the reverse brake 30 to engage and disengage the reverse brake 30. Furthermore, the TCU 40 controls the driving of the lock-up clutch duty solenoid 50a that makes up the valve body 50, adjusts the hydraulic pressure (lock-up apply pressure) supplied to the lock-up clutch 25 (apply chamber), and engages and disengages the lock-up clutch 25. The TCU 40 functions as a control unit described in the claims.

[0029] Here, on the vehicle floor (center console), etc., a shift lever (select lever) 51 is provided that receives an operation by the driver to selectively switch the operating state (range) of the continuously variable transmission 20. A range switch 59 is attached to the shift lever 51 so as to move in conjunction with the shift lever 51 and detect the selected position of the shift lever 51. The range switch 59 is connected to the TCU 40, and the detected selected position of the shift lever 51 is read into the TCU 40. In addition, the shift lever 51 can selectively switch between the "D" range, "M" range, parking "P" range, reverse "R" range, and neutral "N" range. Instead of the shift lever 51, for example, a switch-type selection mechanism may be used.

[0030] Here, when the shift lever 51 is operated and the D range (forward driving range) is selected, ATF is supplied to the hydraulic chamber of the forward clutch 29, and ATF is discharged from the hydraulic chamber of the reverse brake 30. As a result, the forward clutch 29 is in the engaged state, the reverse brake 30 is in the released state, and the vehicle can move forward. On the other hand, when the shift lever 51 is operated and the R range (reverse driving range) is selected, ATF is supplied to the hydraulic chamber of the reverse brake 30, and ATF is discharged from the hydraulic chamber of the forward clutch 29. As a result, the reverse brake 30 is in the engaged state, the forward clutch 29 is in the released state, and the vehicle can move backward. When the shift lever 51 is operated and the N range or P range is selected, ATF is discharged from the hydraulic chamber of the forward clutch 29 and the hydraulic chamber of the reverse brake 30, respectively. As a result, the forward clutch 29 and the reverse brake 30 are each in the released state (the transmission of the engine driving force is interrupted), and the vehicle is in the neutral state.

[0031] Connected to the TCU 40 are a primary pulley rotation sensor 57 for detecting the rotational speed of the primary pulley 34, a secondary pulley rotation sensor 58 for detecting the rotational speed (corresponding to the vehicle speed) of the secondary pulley 35, and the like. Further, the TCU 40 is communicably connected to, for example, an ECU 60 that comprehensively controls the engine 10, a vehicle dynamics control unit (hereinafter referred to as "VDCU") 70, and a meter control unit (hereinafter referred to as "MCU") 90 via a CAN (Controller Area Network) 100.

[0032] The TCU 40, the ECU 60, and the VDCU 70 each include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM whose stored content is retained by a battery or the like, and an input / output I / F and the like.

[0033] In the ECU 60, the cylinder is discriminated from the output of the cam angle sensor described above, and the engine speed is obtained from the change in the rotational position of the crankshaft 15 detected by the output of the crank angle sensor 61. That is, the crank angle sensor 61 functions as the engine speed detection means described in the claims. More specifically, the ECU 60 obtains the stroke average engine speed, which is the average engine speed between predetermined crank angles, based on the change over time in the rotational position of the crankshaft 15 detected by the crank angle sensor 61. For example, when a crank signal is input at BBDC 10° with respect to the bottom dead center BDC at the end of the combustion stroke (expansion stroke) (the same as the top dead center TDC of the compression stroke of the cylinder one ignition order later in the case of a four-cylinder engine), the ECU 60 calculates the stroke average engine speed (hereinafter referred to as "engine speed") based on the stroke time T180 during the 180° period before the signal input (i.e., BTDC 10° CA to BBDC 10° CA).

[0034] Also, in the ECU 60, various information such as the intake air amount, accelerator pedal opening, air-fuel ratio of the air-fuel mixture, and water temperature is acquired based on the detection signals input from the various sensors described above. Then, the ECU 60 comprehensively controls the engine 10 by controlling various devices such as the fuel injection amount, ignition timing, and throttle valve 13 based on the acquired various information.

[0035] Also, in the ECU 60, the engine shaft torque (output torque) of the engine 10 is calculated based on the intake air amount detected by the air flow meter. Then, the ECU 60 transmits information such as the engine speed, engine shaft torque, and accelerator pedal opening to the TCU 40 via the CAN 100.

[0036] The VDCU70 is connected to a brake hydraulic pressure sensor 71 that detects the master cylinder pressure (brake hydraulic pressure) of the brake actuator. The VDCU70 is also connected to wheel speed sensors 72 that detect the rotational speed (vehicle speed) of each wheel of the vehicle. Further, the VDCU70 is connected to a longitudinal acceleration (longitudinal G) sensor 73 that detects the longitudinal acceleration acting on the vehicle, a lateral acceleration (lateral G) sensor 74 that detects the lateral acceleration acting on the vehicle, and so on.

[0037] The VDCU70 drives the brake actuator according to the operation amount of the brake pedal to brake the vehicle, detects vehicle behavior with various sensors (for example, wheel speed sensors 72, acceleration sensors 73, 74, steering angle sensors, acceleration sensors, yaw rate sensors, etc.), and suppresses skidding and ensures vehicle stability during turning by means of brake control by automatic pressurization and torque control of the engine 10. Further, the VDCU70 transmits the detected braking information (brake operation information) such as brake hydraulic pressure and the longitudinal acceleration (longitudinal G), lateral acceleration (lateral G), wheel speed (vehicle speed), etc. to the TCU40 via the CAN100.

[0038] The TCU40 automatically and steplessly changes the gear ratio according to the driving state of the vehicle (for example, vehicle speed, engine rotational speed, accelerator pedal opening degree, etc.) according to the shift map. The shift map corresponding to the automatic shift mode is stored in an EEPROM or the like in the TCU40. Further, the TCU40 controls the duty ratio of the voltage (electric power) applied to the lock-up clutch duty solenoid 50a to adjust the hydraulic pressure of the oil supplied to the apply chamber of the lock-up clutch 25 and controls the engagement and release of the lock-up clutch 25.

[0039] In particular, the TCU40 has a function of increasing the diagnostic frequency of the abnormal fastening (on-fixation abnormality) of the lock-up clutch 25 in the torque converter 21 while preventing misdetection. In the TCU40, the function is realized by the program stored in an EEPROM or the like being executed by a microprocessor.

[0040] When the TCU 40 switches the shift range of the continuously variable transmission 20 from the parking (P) range or neutral (N) range to the forward drive (D) range or reverse drive (R) range, if the turbine speed drops below a predetermined speed (for example, 400 rpm: the engine stall determination threshold value), the TCU 40 performs a diagnosis of abnormal engagement and fixation of the lock-up clutch 25. Further, when the vehicle decelerates and stops, if the turbine speed drops below a predetermined speed (for example, 400 rpm), the TCU 40 performs a diagnosis of abnormal engagement and fixation of the lock-up clutch 25.

[0041] When performing the diagnosis of abnormal engagement and fixation, the TCU 40 counts the number of times the turbine speed and the engine speed cross (the number of times the vertical relationship is reversed). Then, as shown in FIGS. 2 and 6, when the number of times the turbine speed and the engine speed cross (the count value) is equal to or greater than a preset number of times (for example, 4 times), the TCU 40 determines that an abnormal engagement and fixation (on-fixation abnormality) of the lock-up clutch 25 has occurred. Note that FIG. 2 is a diagram for explaining a method of detecting an abnormal engagement and fixation of the lock-up clutch 25 (during engagement and fixation). The horizontal axis in FIG. 2 is time (sec), and the vertical axis is the engine speed and the turbine speed (rpm) (the same applies to FIGS. 3 to 9). FIG. 6 is a diagram showing an example of measured data (changes in the turbine speed and the engine speed) during engagement and fixation.

[0042] By the way, when the lock-up clutch 25 is in a state of being engaged and fixed, after the engine is started and switched from the P range or N range to the D range or R range, or when the vehicle decelerates and stops with the lock-up clutch 25 in a state of being engaged and fixed during driving, feedback control works to maintain the idling rotation of the engine 10, and the turbine speed hunts due to the occurrence of engine friction. On the other hand, since the engine speed sent from the ECU 60 to the TCU 40 is smoothed (due to the average value of 180°CA), it hardly hunts.

[0043] Therefore, when the lock-up clutch 25 is engaged and fixed, when the engine 10 stalls, the turbine speed hunts, causing the turbine speed and the engine speed to cross each other multiple times. Based on such findings, a fastening fixation (failure) is determined from the number of times the turbine speed and the engine speed cross each other when the engine is about to stall. Here, the predetermined number of times used for the fixation determination is set based on, for example, the number of explosions while the engine 10 rotates twice (720 deg). Therefore, for a four-cylinder engine, since there are two explosions, it is set to four times. Also, for a six-cylinder engine, since there are three explosions, it is preferably set to four or more times (for example, six times).

[0044] On the other hand, as shown in FIGS. 3 and 7, the TCU 40 determines that the lock-up clutch 25 is normal (that is, no fastening fixation has occurred) when the number of times the turbine speed and the engine speed cross each other (the number of times the vertical relationship is reversed) is less than a predetermined number of times (for example, four times) and a predetermined time (for example, 0.1 sec) or more has elapsed with the turbine speed being zero. Note that FIG. 3 is a diagram for explaining a method of detecting an abnormal fastening fixation of the lock-up clutch 25 (normal state). FIG. 7 is a diagram showing an example of actual measurement data (changes in turbine speed and engine speed) in the normal state.

[0045] By the way, the engine speed calculated by the ECU 60 and acquired via the CAN 100 may be delayed with respect to the turbine speed calculated by the TCU 40. Therefore, from the viewpoint of improving the abnormality detection accuracy, it is preferable for the TCU 40 to correct (offset) the engine speed so as to eliminate such a delay. More specifically, as shown in FIG. 4, the TCU 40 corrects (offsets) the engine speed based on, for example, the decreasing speed of the engine speed and the deceleration speed of the vehicle speed. Note that FIG. 4 is a diagram for explaining the correction of the engine speed.

[0046] The TCU 40 increases the correction amount (offset amount) as the engine speed decreasing rate increases, and decreases the correction amount (offset amount) as the engine speed decreasing rate decreases. Also, the TCU 40 increases the correction amount (offset amount) as the vehicle speed deceleration rate increases, and decreases the correction amount (offset amount) as the vehicle speed deceleration rate decreases. Then, the TCU 40 counts the number of times the turbine speed and the corrected engine speed cross (the number of times the vertical relationship is reversed), and when the number of times (count value) reaches or exceeds a preset predetermined number of times (for example, 4 times), it determines that there is an abnormal engagement and fixation (on-fixation abnormality) of the lock-up clutch 25.

[0047] The TCU 40 determines that the vehicle decelerates and stops, for example, when the vehicle speed is below a predetermined speed and decreasing, the depression of the accelerator pedal is released, and the brake pedal is depressed. However, in order to prevent misdetection, as shown in FIG. 5, the TCU 40 does not execute abnormal diagnosis during sudden deceleration. In other words, when the vehicle decelerates and stops, the TCU 40 performs an abnormal diagnosis as to whether the lock-up clutch 25 is abnormally engaged and fixed when the deceleration of the vehicle is equal to or less than a predetermined deceleration (for example, 3 m / s^2) (that is, in the case of gentle deceleration). Note that FIG. 5 is a diagram for explaining the operation during sudden deceleration.

[0048] By the way, when the vehicle deceleration is large, the time from when the turbine speed falls below a predetermined speed (for example, 400 rpm) until the vehicle stops, that is, the time during which the number of crossing times can be counted up, becomes short. Therefore, even if the lock-up clutch 25 is abnormally engaged and fixed, there is a possibility that it may be determined to be normal. Thus, misdetection is prevented by prohibiting the determination during sudden deceleration. More specifically, after the turbine speed falls below a predetermined speed (for example, 400 rpm), until the engine 10 stalls, the deceleration threshold value is set to, for example, 3 m / s^2 so that the engine 10 can rotate two or more times (720 deg) (that is, the number of crossing times between the turbine speed and the engine speed can be ensured to be 4 or more times).

[0049] Also, as shown in FIGS. 8 and 9, after starting the abnormality diagnosis as to whether or not the lock-up clutch 25 is fastened and fixed, when the state where the turbine rotational speed is greater than a predetermined rotational speed (for example, 400 rpm) continues for a predetermined time (for example, 0.2 sec) or more, the diagnosis is aborted and the counted number (count value) is reset (returned to zero). Note that FIG. 8 is a diagram for explaining the reset operation of the count value at the time of fastening and fixing. FIG. 9 is a diagram for explaining the reset operation of the count value during normal times (when not to be fastened and fixed).

[0050] The diagnosis result of the fastening and fixing obtained as described above is sent to the MCU 90 via the CAN 100. The MCU 90 is connected to a display unit 91 having, for example, an LCD display disposed in a meter or above a dashboard, and drives the display unit 91 to present, for example, the states and various information of the vehicle, the engine 10, the continuously variable transmission 20, etc. to the driver. In particular, when an abnormality in the fastening and fixing of the lock-up clutch 25 is detected, the MCU 90 issues a warning to the driver. At that time, it is preferable that the MCU 90 drives the display unit 91 to turn on a warning lamp, display characters such as "An abnormality (fastening and fixing) has occurred in the lock-up clutch", etc. Also, a warning sound may be output at the same time.

[0051] Next, the operation of the abnormality detection device 1 for the lock-up clutch will be described with reference to FIG. 10. FIG. 10 is a flowchart showing the processing procedure of the fastening and fixing abnormality diagnosis process by the abnormality detection device 1 for the lock-up clutch. This process is repeatedly executed in the TCU 40 at every predetermined time (for example, every 10 ms).

[0052] First, in step S100, it is determined whether the shift range of the continuously variable transmission 20 has been switched from the parking (P) range or the neutral (N) range to the forward drive (D) range or the reverse drive (R) range (whether it has been engaged). Here, if the range has been switched (engaged), the process proceeds to step S106. On the other hand, if the range has not been switched (not engaged), the process proceeds to step S102.

[0053] In step S102, it is determined whether the vehicle is decelerating and stopping. Here, if it is determined that the vehicle is not decelerating and stopping, the process exits temporarily from this process. On the other hand, when it is determined that the vehicle is decelerating and stopping, the process proceeds to step S104.

[0054] In step S104, it is determined whether the vehicle is decelerating rapidly (for example, whether the deceleration is 3 m / s^2 or more). Here, if it is determined that the vehicle is decelerating rapidly, the process exits temporarily from this process. On the other hand, when it is determined that the vehicle is not decelerating rapidly (decelerating slowly), the process proceeds to step S106.

[0055] In step S106, it is determined whether the turbine rotational speed has fallen below a predetermined rotational speed (for example, 400 rpm). Here, if the turbine rotational speed has fallen below the predetermined rotational speed, the process proceeds to step S110. On the other hand, when the turbine rotational speed has not fallen below the predetermined rotational speed, the process proceeds to step S108.

[0056] In step S108, when the state where the turbine rotational speed is higher than a predetermined rotational speed (for example, 400 rpm) continues for a predetermined time (for example, 0.2 sec) or more, the diagnosis is aborted and the counted number (count value) is reset (returned to zero). Then, the process exits temporarily from this process.

[0057] On the one hand, in step S110, the engine speed is corrected (offset) based on the decrease rate of the engine speed and the deceleration rate of the vehicle speed.

[0058] Next, in step S112, it is determined whether the turbine speed and the engine speed after correction (after offset) cross each other (whether the vertical relationship has changed). Here, when both cross each other, in step S114, after the count value that counts the number of times both cross each other is incremented (for example, +1), the process proceeds to step S116. On the other hand, when both do not cross each other, the process proceeds to step S116 without incrementing the count value.

[0059] In step S116, it is determined whether the count value (the number of times the turbine speed and the engine speed cross each other) is equal to or greater than a preset number of times (for example, 4 times). Here, when the count value is equal to or greater than the preset number of times, the process proceeds to step S118. On the other hand, when the count value is less than the preset number of times, the process proceeds to step S120.

[0060] In step 118, it is determined that the lock-up clutch 25 is engaged and fixed. Then, the process exits from this process once.

[0061] In step S120, it is determined whether a predetermined time (for example, 0.1 sec) or more has elapsed with the turbine speed being zero. Here, when the predetermined time has not elapsed with the turbine speed being zero, the process returns to step S106, and the processes of steps S106 to S120 described above are repeatedly executed again. On the other hand, when the predetermined time has elapsed with the turbine speed being zero, in step S122, it is determined that the lock-up clutch 25 is normal (that is, no engagement and fixation has occurred). Then, the process exits from this process once.

[0062] As described in detail above, according to the present embodiment, when the shift range of the continuously variable transmission 20 is switched from the parking (P) range or the neutral (N) range to the forward drive (D) range or the reverse drive (R) range, it is possible to detect an abnormal fastening and fixing of the lock-up clutch 25. That is, it is possible to detect an abnormality in the stopped state. Also, when the vehicle decelerates and stops, it is possible to detect an abnormal fastening and fixing of the lock-up clutch 25, and the detection frequency (diagnosis frequency) can be increased.

[0063] Further, according to the present embodiment, the number of times the turbine rotational speed and the engine rotational speed cross (the number of times the vertical relationship is reversed) is counted, and when the number of times becomes equal to or more than a predetermined number of times (for example, 4 times) set in advance, it is determined that an abnormal fastening and fixing (on-fixing abnormality) of the lock-up clutch 25 has occurred. On the other hand, when the number of times the turbine rotational speed and the engine rotational speed cross does not become equal to or more than the predetermined number of times, and when a predetermined time or more has elapsed in a state where the turbine rotational speed is zero, it is determined that the lock-up clutch 25 is normal (no fastening and fixing has occurred). Therefore, it is possible to more accurately detect an abnormal fastening and fixing of the lock-up clutch 25.

[0064] As a result, according to the present embodiment, it is possible to increase the diagnosis frequency of an abnormal fastening and fixing (on-fixing abnormality) of the lock-up clutch 25 in the torque converter 21 while preventing false detection.

[0065] According to the present embodiment, the engine rotational speed is corrected (offset) based on the decrease rate of the engine rotational speed and the deceleration rate of the vehicle speed. Therefore, even if the engine rotational speed obtained via the CAN 100 and obtained by the ECU 60 is delayed with respect to the turbine rotational speed calculated by the TCU 40, by correcting the delay, the detection accuracy of the fixing diagnosis can be improved.

[0066] According to this embodiment, when the vehicle decelerates and stops, an abnormality determination is made as to whether the lock-up clutch 25 is engaged and fixed when the deceleration of the vehicle is equal to or less than a predetermined deceleration (for example, 3 m / s^2). Therefore, false detection can be prevented by prohibiting the fixation determination during a rapid deceleration in which the engine 10 cannot make two revolutions from the time when the turbine speed becomes equal to or less than a predetermined speed (for example, 400 rpm) until the vehicle stops.

[0067] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above embodiment, the case where the present invention is applied to the continuously variable transmission (CVT) 20 has been described as an example. However, the present invention can also be applied to a stepped automatic transmission (step AT) or the like.

[0068] In the above embodiment, the forward and reverse switching mechanism 27 is arranged in front of the primary pulley 34, but it may be arranged behind the secondary pulley 35.

[0069] In the above embodiment, a hydraulic lock-up clutch 25 is used, but for example, an electromagnetic lock-up clutch can also be used.

[0070] In the above embodiment, the ECU 60 that controls the engine 10 and the TCU 40 that controls the continuously variable transmission 20 are configured with separate hardware and connected to be mutually communicable via the CAN 100. However, both may be configured with integrated hardware.

Explanation of Reference Numerals

[0071] 1 Abnormality detection device for lock-up clutch 10 Engine 20 Continuously variable transmission 21 Torque converter 22 Pump impeller 23 Turbine runner 24 Stator 25 Lock-up clutch 26 Turbine shaft 27 Forward and reverse switching mechanism 28 Planetary gear train 29 Forward clutch 30 Reverse brake 34 Primary pulley 35 Secondary pulley 36 Chain 40 TCU 50 Valve body (control valve) 50a Lock-up clutch duty solenoid 51 Shift lever 56 Turbine speed sensor 57 Primary pulley rotation sensor 58 Secondary pulley rotation sensor 59 Range switch 60 ECU 61 Crank angle sensor 62 Accelerator pedal sensor 70 VDCU 71 Brake hydraulic pressure sensor 72 Wheel speed sensor 73 Longitudinal and lateral acceleration sensor 74 Lateral acceleration sensor 90 MCU 91 Display unit 100 CAN

Claims

1. a turbine speed detection means for detecting the rotational speed of a turbine of a torque converter interposed between an engine and an automatic transmission; an engine speed detection means for detecting the rotational speed of the engine; a control unit for controlling engagement and release of a lock-up clutch of the torque converter, and when the control unit switches the shift range of the automatic transmission from the parking range or neutral range to the forward drive range or reverse drive range, and when the vehicle decelerates and stops, the control unit counts the number of times the turbine rotational speed and the engine rotational speed cross each other until the engine stalls, and when the number of times is equal to or more than a predetermined number of times, determines that there is an abnormal engagement and fixation of the lock-up clutch. An abnormal detection device for a lock-up clutch characterized by the above.

2. The control unit according to claim 1, wherein when the number of times does not reach the predetermined number of times and a predetermined time or more has elapsed in a state where the turbine rotational speed is zero, determines that the lock-up clutch is normal. An abnormal detection device for a lock-up clutch.

3. When the control unit switches the shift range of the automatic transmission from the parking range or neutral range to the forward drive range or reverse drive range, and when the vehicle decelerates and stops, when the turbine rotational speed is lower than a predetermined rotational speed, the control unit counts the number of times the turbine rotational speed and the engine rotational speed cross each other until the engine stalls, and when the number of times is equal to or more than a predetermined number of times, determines that there is an abnormal engagement and fixation of the lock-up clutch. An abnormal detection device for a lock-up clutch according to claim 1 or 2.

4. The control unit corrects the engine rotational speed based on the rate of decrease of the engine rotational speed and the deceleration of the vehicle speed, counts the number of times the turbine rotational speed and the corrected engine rotational speed cross each other until the engine stalls, and when the number of times is equal to or more than a predetermined number of times, determines that there is an abnormal engagement and fixation of the lock-up clutch. The control unit increases the reduction correction amount as the engine speed reduction rate increases, decreases the reduction correction amount as the engine speed reduction rate decreases, increases the reduction correction amount as the vehicle speed deceleration rate increases, and decreases the reduction correction amount as the vehicle speed deceleration rate decreases. The lock-up clutch abnormality detection device according to claim 3, characterized in that.

5. When the vehicle decelerates and stops, the control unit performs an abnormality determination as to whether or not the lock-up clutch is fastened and fixed when the deceleration of the vehicle is equal to or less than a predetermined deceleration. The lock-up clutch abnormality detection device according to claim 3 or 4, characterized in that.

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