JP7704628B2 - Anomaly detection device for continuously variable transmissions - Google Patents

Description

The present invention relates to an abnormality detection device for a continuously variable transmission, and in particular to an abnormality detection device for a continuously variable transmission that detects abnormal characteristics of a primary pressure sensor that detects the hydraulic pressure value of oil supplied to a primary pulley that constitutes a continuously variable transmission.

In recent years, continuously variable transmissions (CVTs) such as chain and belt types have been widely used as automatic transmissions for vehicles, as they can change the gear ratio steplessly, are free of gear shift shock, and improve fuel economy. A continuously variable transmission such as a chain type has a primary pulley (drive pulley) provided on the input shaft, a secondary pulley (driven pulley) provided on the output shaft, and a power transmission element such as a chain that is stretched across these pulleys. Engine torque generated by the engine is transmitted from the primary pulley to the secondary pulley via the power transmission element such as the chain. Furthermore, a continuously variable transmission changes the gear ratio steplessly by changing the groove width of each pulley to change the winding diameter of the power transmission element.

Here, the clamping force (pulley side pressure) applied to each of the primary and secondary pulleys is controlled by adjusting the oil pressure of the oil supplied to the primary pulley and the oil pressure of the oil supplied to the secondary pulley. At that time, the control unit performs feedback (F/B) control so that the target oil pressure calculated based on the operating state matches the actual oil pressure detected by the oil pressure sensor.

In addition, to perform appropriate feedback control, abnormality detection (fault diagnosis) is performed to detect abnormalities in the primary pressure sensor, which detects the primary pressure, which is the hydraulic pressure value of the oil supplied to the primary pulley, and the secondary pressure sensor, which detects the secondary pressure, which is the hydraulic pressure value of the oil supplied to the secondary pulley, such as abnormalities in open mode (disconnection abnormality), abnormalities in short mode (short circuit abnormality), and sticking abnormality (abnormality in which a constant value is continuously output) (see, for example, Patent Document 1).

Furthermore, a method has been proposed for detecting abnormal sensor characteristics, such as when the secondary pressure sensor outputs a value lower than the actual secondary pressure (actual secondary pressure) or a value higher than the actual secondary pressure (actual secondary pressure).

More specifically, as a method for detecting (diagnosing) such abnormal characteristics, for example, a method has been proposed that utilizes the fact that the actual oil pressure becomes 0 MPa when the ignition is turned off (engine is stopped) and hydraulic feedback control is stopped, and determines (detects) whether the sensor characteristics are abnormal based on whether the sensor value at that time is near 0 MPa (whether it is outputting a voltage value, etc., within an appropriate range).

Japanese Patent Application Publication No. 6-213316

However, depending on the configuration of the hydraulic circuit that adjusts the primary pressure, for example, when the line pressure drops after the ignition is turned off (engine is stopped), there may be insufficient hydraulic pressure to operate the downshift valve that lowers the primary pressure, making it impossible to operate the downshift valve as instructed and making it impossible to lower the primary pressure to 0 MPa. Thus, for example, in the case of a hydraulic circuit that cannot make the primary pressure zero when the ignition is turned off (engine is stopped), the above-mentioned anomaly detection method has the problem of being unable to detect an abnormality in the characteristics (rationality) of the primary pressure sensor.

The present invention was made to solve the above problems, and aims to provide an abnormality detection device for a continuously variable transmission that can detect abnormal characteristics of a primary pressure sensor regardless of the configuration of the hydraulic circuit that adjusts the primary pressure (for example, even in a hydraulic circuit in which the primary pressure does not become zero when the ignition is off (engine is stopped)).

The abnormality detection device for a continuously variable transmission according to the present invention includes a primary pressure sensor that detects a primary pressure, which is the hydraulic pressure value of the oil supplied to the primary pulley, a secondary pressure sensor that detects a secondary pressure, which is the hydraulic pressure value of the oil supplied to the secondary pulley, a primary rotation speed sensor that detects a primary rotation speed, which is the rotation speed of the primary pulley, a secondary rotation speed sensor that detects a secondary rotation speed, which is the rotation speed of the secondary pulley, and a control unit that controls the gear ratio by adjusting each of the hydraulic pressure of the oil supplied to the primary pulley and the hydraulic pressure of the oil supplied to the secondary pulley, and the control unit detects a predetermined diagnostic condition when the predetermined diagnostic condition is met and When feedback control using the primary pressure is stopped, a clamping force ratio is calculated based on the gear ratio calculated from the ratio between the primary rotation speed and the secondary rotation speed, and the input torque to the primary pulley and the secondary pressure. Based on the clamping force ratio and the secondary pressure, an upper limit and a lower limit of the diagnostic primary pressure for diagnosing a characteristic abnormality of the primary pressure sensor are set. If the primary pressure is less than the upper limit and greater than or equal to the lower limit of the diagnostic primary pressure, the primary pressure sensor is determined to be normal, and if the primary pressure is greater than or equal to the upper limit or less than the lower limit of the diagnostic primary pressure, the primary pressure sensor is determined to be abnormal.

According to the continuously variable transmission abnormality detection device of the present invention, when a predetermined diagnostic condition is met and feedback control using the primary pressure is stopped, a gear ratio is calculated based on the ratio between the primary rotation speed and the secondary rotation speed, and the input torque to the primary pulley and the secondary pressure, and an upper limit value and a lower limit value of the diagnostic primary pressure (i.e., an appropriate range of the primary pressure) for diagnosing a characteristic abnormality of the primary pressure sensor are set based on the clamping force ratio and the secondary pressure. Then, when the primary pressure is less than the upper limit value and greater than or equal to the lower limit value of the diagnostic primary pressure (within the appropriate range), the primary pressure sensor is determined to be normal, and when the primary pressure is greater than or equal to the upper limit value or less than the lower limit value of the diagnostic primary pressure (not within the appropriate range), the primary pressure sensor is determined to be abnormal in characteristics. Therefore, for example, even in a hydraulic circuit in which the primary pressure does not become zero when the ignition is off (when the engine is stopped), an abnormality in the characteristics (rationality) of the primary pressure sensor can be detected.

According to the present invention, it is possible to detect abnormalities in the characteristics (rationality) of the primary pressure sensor regardless of the configuration of the hydraulic circuit that adjusts the primary pressure (for example, even in a hydraulic circuit in which the primary pressure does not become zero when the ignition is off (engine is stopped)).

1 is a block diagram showing a configuration of an abnormality detection device for a continuously variable transmission according to an embodiment; FIG. 4 is a diagram showing an example of a hydraulic circuit for adjusting a primary pressure. FIG. 13 is a diagram showing an example of a clamping force ratio upper limit map. 4 is a flowchart showing a procedure of characteristic abnormality detection processing performed by the abnormality detection device for a continuously variable transmission.

Below, a preferred embodiment of the present invention will be described in detail with reference to the drawings. Note that in the drawings, the same reference numerals will be used for the same or corresponding parts. In addition, in each drawing, the same elements will be given the same reference numerals, and duplicate explanations will be omitted.

First, the configuration of the continuously variable transmission abnormality detection device 1 according to the embodiment will be described with reference to both Figures 1 and 2. Figure 1 is a block diagram showing the configuration of the continuously variable transmission abnormality detection device 1 and a continuously variable transmission 30 to which the continuously variable transmission abnormality detection device 1 is applied. Figure 2 is a diagram showing an example of a hydraulic circuit 80 that adjusts the primary pressure.

The engine 10 may be of any type, but may be, for example, a horizontally opposed, four-cylinder gasoline engine with direct injection. In the engine 10, air taken in from an air cleaner (not shown) is throttled by an electronically controlled throttle valve (hereinafter also simply referred to as a "throttle valve") 13 provided in the intake pipe, passes through an intake manifold, and is taken in by each cylinder formed in the engine 10. Here, the amount of air taken in from the air cleaner is detected by an air flow meter 61. Furthermore, the throttle valve 13 is provided with a throttle opening sensor 14 that detects the opening of the throttle valve 13. An injector that injects fuel is attached to each cylinder. In addition, each cylinder is provided with a spark plug that ignites the mixture, and an igniter-integrated coil that applies high voltage to the spark plug. In each cylinder of the engine 10, the mixture of the taken in air and the fuel injected by the injector is ignited by the spark plug and combusted. After combustion, exhaust gases are discharged through the exhaust pipe.

In addition to the air flow meter 61 and throttle opening sensor 14 described above, a cam angle sensor for identifying the cylinders of the engine 10 is attached near the camshaft of the engine 10. Also, a crank angle sensor for detecting the position of the crankshaft is attached near the crankshaft of the engine 10. These sensors are connected to an engine control unit (hereinafter referred to as "ECU") 60, which will be described later. Also connected to the ECU 60 are various sensors, such as an accelerator pedal sensor 62 that detects the amount of depression of the accelerator pedal, i.e., the amount of operation of the accelerator pedal, and a water temperature sensor that detects the temperature of the cooling water for the engine 10.

The output shaft 15 of the engine 10 is connected to a continuously variable transmission 30 that converts and outputs the driving force from the engine 10 via a torque converter 20 that has a clutch function and a torque amplification function.

The torque converter 20 is mainly composed of a pump impeller 21, a turbine runner 22, and a stator 23. The pump impeller 21 connected to the output shaft 15 generates the flow of oil, and the turbine runner 22 arranged opposite the pump impeller 21 receives power from the engine 10 via the oil to drive the output shaft. The stator 23 located between the two rectifies the exhaust flow (return) from the turbine runner 22 and returns it to the pump impeller 21, generating a torque amplification effect.

The torque converter 20 also has a lock-up clutch 24 that directly connects the input and output. When the lock-up clutch 24 is not engaged (non-lock-up state), the torque converter 20 amplifies the driving force of the engine 10 and transmits it to the continuously variable transmission 30, and when the lock-up clutch 24 is engaged (lock-up state), the torque converter 20 transmits the driving force of the engine 10 directly to the continuously variable transmission 30. The rotation speed (turbine rotation speed) of the turbine runner 22 that constitutes the torque converter 20 is detected by a turbine rotation speed sensor 56. The detected turbine rotation speed is output to a transmission control unit (hereinafter referred to as "TCU") 40, which will be described later.

The continuously variable transmission 30 has a primary shaft 32 that is connected to the output shaft 25 of the torque converter 20 via a reduction gear 31 (or forward/reverse switching mechanism), and a secondary shaft 37 that is arranged in parallel to the primary shaft 32.

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 attached to the primary shaft 32 so as to be slidable in the axial direction of the primary shaft 32 opposite the fixed sheave 34a, and is configured to be able to change the cone surface spacing between the sheaves 34a and 34b, i.e., the pulley groove width. 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 attached to the secondary shaft 37 so as to be slidable in the axial direction of the secondary shaft 37 opposite the fixed sheave 35a, and is configured to be able to change the pulley groove width.

A chain 36 that transmits driving force is stretched between the primary pulley 34 and the secondary pulley 35. The gear ratio is continuously changed by changing the groove width of the primary pulley 34 and the secondary pulley 35 to change the ratio of the winding diameter of the chain 36 to each of the pulleys 34, 35 (pulley ratio). The power transmission mechanism consisting of the primary pulley 34, the secondary pulley 35, and the chain 36 is called a variator. Here, if the winding diameter of the chain 36 around the primary pulley 34 is Rp and the winding diameter around the secondary pulley 35 is Rs, the gear ratio i is expressed as i = Rs/Rp. If the rotation speed of the primary pulley 34 is Np and the rotation speed of the secondary pulley 35 is Ns, the gear ratio i is expressed as i = Np/Ns.

Here, a hydraulic chamber (hydraulic cylinder chamber) 34c is formed in the primary pulley 34 (movable sheave 34b). Meanwhile, a hydraulic chamber (hydraulic cylinder 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 pressure introduced into the hydraulic chamber 34c of the primary pulley 34 and the secondary pressure introduced into the hydraulic chamber 35c of the secondary pulley 35. Here, "clamping force Fp of the primary pulley 34 = primary pressure Pp × pressure-receiving area of the hydraulic chamber 34c" and "clamping force Fs of the secondary pulley 35 = secondary pressure Ps × pressure-receiving area of the hydraulic chamber 35c". The ratio (Fp/Fs) of the primary pulley clamping force Fp to the secondary pulley clamping force Fs is called the clamping force ratio.

The hydraulic pressure for shifting the continuously variable transmission 30, i.e., the primary pressure and secondary pressure described above, are adjusted by a valve body (control valve) 50. The valve body 50 adjusts the hydraulic pressure discharged from the oil pump by opening and closing oil passages formed in the valve body 50 using multiple spool valves and solenoid valves (electromagnetic valves) that operate the spool valves, and supplies the hydraulic pressure to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35. The valve body 50 also generates an appropriate clamping force (pulley side pressure) that does not cause slippage of the chain 36. Here, the secondary pressure supplied to the hydraulic chamber 35c of the secondary pulley 35 is adjusted according to the transmission torque required for the chain 36. The primary pressure supplied to the hydraulic chamber 34c of the primary pulley 34 is adjusted to a value according to the target gear ratio, etc. The valve body 50 also supplies hydraulic pressure to, for example, a forward/reverse switching mechanism that switches the vehicle forward/reverse.

Here, a shift lever (select lever) 51 is provided on the floor or center console of the vehicle, which accepts the driver's operation to selectively switch between an automatic transmission mode ("D" range) and a manual transmission mode ("M" range). A range switch 59 is attached to the shift lever 51, which is connected to move in conjunction with the shift lever 51 and detects 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 to the "D" range and "M" range, the shift lever 51 can selectively switch between the parking "P" range, reverse "R" range, and neutral "N" range.

The shift lever 51 incorporates an M-range switch 52 that is turned on when the shift lever 51 is in the M-range position, i.e., when the manual shift mode is selected, and turned off when the shift lever 51 is in the D-range position, i.e., when the automatic shift mode is selected. The M-range switch 52 is also connected to the TCU 40.

On the other hand, a plus (+) paddle switch 54 and a minus (-) paddle switch 55 are provided on the rear side of the steering wheel 53 to receive a shift operation (shift request) by the driver in the manual shift mode (hereinafter, the plus paddle switch 54 and the minus paddle switch 55 are sometimes collectively referred to as "paddle switches 54, 55"). The plus paddle switch 54 is used when manually upshifting, and the minus paddle switch 55 is used when manually downshifting.

The plus paddle switch 54 and the minus paddle switch 55 are connected to the TCU 40, and the switch signals output from the paddle switches 54, 55 are read into the TCU 40. Also connected to the TCU 40 are a primary rotation speed sensor 57 that detects the rotation speed of the primary pulley 34, and a secondary rotation speed sensor 58 that detects the rotation speed of the secondary pulley 35. Also connected to the TCU 40 are a primary pressure sensor 71 that detects the pressure (hydraulic pressure) of the oil supplied to the primary pulley 34, a secondary pressure sensor 72 that detects the pressure (hydraulic pressure) of the oil supplied to the secondary pulley 35, and the like.

As described above, the continuously variable transmission 30 has two shift modes that can be selectively switched by operating the shift lever 51: automatic shift mode and manual shift mode. The automatic shift mode is selected by operating the shift lever 51 to D range, and is a mode in which the gear ratio is automatically changed according to the vehicle's driving conditions. The manual shift mode is selected by operating the shift lever 51 to M range, and is a mode in which the gear ratio is changed according to the driver's shift operation (operation of the paddle switches 54, 55).

The clamping force control and the speed change control of the continuously variable transmission 30 are executed by the TCU 40. That is, the TCU 40 controls the operation of the solenoid valve (electromagnetic valve) constituting the valve body 50 described above, thereby adjusting the hydraulic pressure supplied to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35, thereby changing the clamping force and the speed change ratio of the continuously variable transmission 30. That is, the TCU 40 functions as a control unit as described in the claims.

Figure 2 shows the hydraulic circuit 80 that adjusts the primary pressure (upshift/downshift) and is configured inside the valve body 50.

The upshift solenoid 81 adjusts the pilot pressure created from the line pressure according to the duty ratio applied by the TCU 40 to generate an upshift control pressure. The generated upshift control pressure is supplied to the upshift valve 83 via an upshift control pressure oil passage 91. Note that the upshift solenoid 81 is preferably, for example, a duty solenoid whose opening is adjusted according to the duty ratio. The upshift solenoid 81 is controlled by the TCU 40.

The upshift valve 83 is connected to the line pressure oil passage 90, the upshift control pressure oil passage 91, and the primary pressure oil passage 93. The upshift valve 83 accommodates a spool 83a inside so that it can slide freely in the axial direction. A spring 83b is arranged at the end of the spool 83a, and the spool 83a is driven in the axial direction according to the balance between the pressing force (upshift control pressure x pressure receiving area) due to the upshift control pressure generated by the upshift solenoid 81 and the spring force (biasing force) of the spring 83b. During an upshift, the line pressure is adjusted according to the upshift control pressure to generate an upshift oil pressure. The generated upshift oil pressure is supplied to the primary pulley 34 (oil chamber 34c) via the primary pressure oil passage 93. As a result, the gear ratio is upshifted.

Meanwhile, the downshift solenoid 82 adjusts the pilot pressure created from the line pressure according to the duty ratio applied by the TCU 40 to generate downshift control pressure. The generated downshift control pressure is supplied to the downshift valve 84 via a downshift control pressure oil passage 92. Note that the downshift solenoid 82 is preferably, for example, a duty solenoid whose opening is adjusted according to the duty ratio. The downshift solenoid 82 is controlled by the TCU 40.

The downshift valve 84 is connected to a primary pressure oil passage 93, a downshift control pressure oil passage 92, and a drain oil passage 94. During a downshift, the downshift valve 84 drains oil from the primary pulley 34 (hydraulic chamber 34c) through the drain oil passage 94 according to the downshift control pressure. As a result, the gear ratio is downshifted. Note that, in the hydraulic circuit 80, when the line pressure drops after the ignition is turned off (after the engine is stopped), there is insufficient hydraulic pressure to operate the downshift valve 84, which lowers the primary pressure, and the downshift valve 84 cannot be operated as instructed, and the primary pressure cannot be lowered to 0 MPa.

Returning to FIG. 1, the TCU 40 is connected to the ECU 60, which provides overall control of the engine 10, etc., via a CAN (Controller Area Network) 100, so that they can communicate with each other.

The TCU 40 and ECU 60 each include a microprocessor that performs calculations, an EEPROM that stores programs for causing the microprocessor to execute various processes, a RAM that stores various data such as the results of calculations, a backup RAM whose stored contents are maintained by a battery, and an input/output I/F.

The ECU 60 identifies the cylinder from the output of the cam angle sensor, and determines the engine speed from the change in the rotational position of the crankshaft detected by the output of the crank angle sensor. The ECU 60 also acquires various information such as the intake air volume, accelerator pedal operation amount, air-fuel ratio of the mixture, and water temperature based on the detection signals input from the various sensors described above. The ECU 60 also calculates the engine torque of the engine 10 based on, for example, the engine speed and the intake air volume. Here, the engine torque of the engine 10 can be obtained by, for example, storing a map (engine torque map) that defines the relationship between the engine speed, the intake air volume, and the engine torque in advance, and searching the engine torque map. The ECU 60 then comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices based on the acquired various information. The ECU 60 transmits information such as the engine speed, accelerator pedal operation amount, and engine torque to the TCU 40 via the CAN 100.

The TCU 40 receives various information such as engine speed, accelerator pedal operation amount, and engine torque (i.e., variator input torque) transmitted from the ECU 60. The TCU 40 also receives vehicle speed information detected by, for example, a wheel speed sensor through the CAN 100.

Then, the TCU 40 drives the upshift solenoid 81 and the downshift solenoid 82 according to the shift map based on various information acquired from the above-mentioned various sensors, etc. As a result, the gear ratio is automatically changed steplessly according to the driving state of the vehicle (e.g., accelerator pedal operation amount and vehicle speed, etc.). The shift map is stored in an EEPROM or the like in the TCU 40. The TCU 40 also adjusts the clamping force (pulley lateral pressure) of the secondary pulley 35 based on the engine torque of the engine 10 received from the ECU 60 via the CAN 100.

In particular, the TCU 40 has the function of detecting abnormalities in the characteristics (rationality) of the primary pressure sensor 71, regardless of the configuration of the hydraulic circuit that adjusts the primary pressure (for example, even in a hydraulic circuit 80 in which the primary pressure does not become zero when the ignition is turned off (engine is stopped)). In the TCU 40, this function is realized by the microprocessor executing a program stored in the EEPROM.

When a predetermined diagnostic condition is met and feedback control using the primary pressure is stopped, the TCU 40 calculates a clamping force ratio, which is the ratio between the clamping force of the primary pulley 34 and the clamping force of the secondary pulley 35, based on the gear ratio calculated from the ratio of the primary rotation speed to the secondary rotation speed and the torque ratio, which is the ratio between the torque transmittable by the variator (determined by the gear ratio of the variator and the clamping force of the variator (secondary pulley pressure)) and the variator input torque, and sets upper and lower limits of the diagnostic primary pressure for diagnosing abnormalities in the characteristics (rationality) of the primary pressure sensor 71 based on the clamping force ratio and the secondary pressure.

Then, if the state in which the primary pressure is less than the upper limit value and greater than or equal to the lower limit value of the diagnostic primary pressure has continued for a predetermined time (e.g., 1 second) or more, the TCU 40 determines that the primary pressure sensor 71 is normal. On the other hand, if the state in which the primary pressure is greater than or equal to the upper limit value or less than the lower limit value of the diagnostic primary pressure has continued for a predetermined time (e.g., 1 second) or more, the TCU 40 determines that the primary pressure sensor 71 has an abnormal characteristic.

At that time, the TCU 40 determines that the predetermined diagnostic condition is met, for example, when the vehicle speed is equal to or greater than a predetermined value (e.g., 10 km/h), and the change in the target secondary pressure (speed of change, amount of change), the change in the target gear ratio (speed of change, amount of change), and the change in the input torque (accelerator pedal operation amount) (speed of change, amount of change) are each within a predetermined range for a predetermined time (e.g., 1 second) or more (i.e., when they are approximately constant and stable). Note that the predetermined diagnostic condition may also include, for example, that no failure (abnormality) that stops the diagnosis has occurred, that the difference between the target secondary pressure and the actual secondary pressure is equal to or less than a predetermined value, that the difference between the target gear ratio and the actual gear ratio is equal to or less than a predetermined value, that the actual line pressure is equal to or less than a predetermined value, that the engine water temperature is equal to or greater than a predetermined value, that the vehicle is in the D range (forward driving range), and that the actual gear ratio is within a predetermined range.

More specifically, the TCU 40 stores in advance in an EEPROM or the like a clamping force ratio upper limit map that defines the relationship between the gear ratio, the torque ratio, which is the ratio between the torque transmittable by the variator and the variator input torque, and the upper limit of the clamping force ratio, and searches the clamping force ratio upper limit map using the gear ratio and the torque ratio to obtain the upper limit of the clamping force ratio. The TCU 40 then sets the upper limit of the primary pressure for diagnosis based on the upper limit of the clamping force ratio and the secondary pressure.

Similarly, the TCU 40 stores in advance in an EEPROM or the like a clamping force ratio lower limit map that defines the relationship between the gear ratio, the torque ratio, and the lower limit of the clamping force ratio, and searches the clamping force ratio lower limit map using the gear ratio and the torque ratio to obtain the lower limit of the clamping force ratio. The TCU 40 then sets the lower limit of the primary pressure for diagnosis based on the lower limit of the clamping force ratio and the secondary pressure.

Here, an example of the clamping force ratio upper limit map is shown in FIG. 3. In FIG. 3, the horizontal axis is the torque ratio, and the vertical axis is the actual gear ratio. In the clamping force ratio upper limit map, an upper limit value of the clamping force ratio (a value taking into account the amount of variation (upper limit)) is given for each combination (grid point) of the torque ratio and the gear ratio. Note that in the clamping force ratio upper limit map, the upper limit value of the clamping force ratio is set to a higher value as the torque ratio increases, and the upper limit value of the clamping force ratio is set to a higher value as the gear ratio decreases. Note that the clamping force ratio lower limit map is similar to the clamping force ratio upper limit map, except that a value taking into account the amount of variation (lower limit) is set, so a detailed explanation is omitted here.

More specifically, the TCU 40 sets the upper limit value of the diagnostic primary pressure based on the following equation (1).
Primary pressure upper limit for diagnosis = {clamping force ratio upper limit map (gear ratio, torque ratio) search value × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area ... (1)
In addition, data for the secondary cylinder pressure-receiving area and the primary cylinder pressure-receiving area based on design specifications and the like is stored in advance in a memory or the like.

Similarly, the TCU 40 sets the lower limit value of the diagnostic primary pressure based on the following equation (2).
Primary pressure lower limit for diagnosis = {clamping force ratio lower limit map (gear ratio, torque ratio) search value x (secondary pressure x secondary cylinder pressure area)} / primary cylinder pressure area ... (2)

At this time, it is preferable that the TCU 40 sets the upper and lower limits of the diagnostic primary pressure taking into account the variation in detection by the secondary pressure sensor 72.

Next, the operation of the continuously variable transmission abnormality detection device 1 will be described with reference to FIG. 4. FIG. 4 is a flowchart showing the procedure for characteristic abnormality detection processing by the continuously variable transmission abnormality detection device 1. This processing is repeatedly executed by the TCU 40 at predetermined time intervals (e.g., every 10 ms).

In step S100, the primary rotation speed, secondary rotation speed, primary pressure, secondary pressure, etc. are read. Next, in step S102, a determination is made as to whether or not a predetermined diagnostic condition (including the fact that feedback control using the primary pressure has been stopped) is met. If the predetermined diagnostic condition is not met, the process is temporarily terminated. On the other hand, if the predetermined diagnostic condition is met, the process proceeds to step S104. The predetermined diagnostic condition is as described above, so a detailed explanation will be omitted here.

In step S104, the upper and lower limits of the diagnostic primary pressure are set to diagnose abnormalities in the characteristics (rationality) of the primary pressure sensor 71. Note that the method for setting the upper and lower limits of the diagnostic primary pressure is as described above, so a detailed explanation is omitted here.

Next, in step S106, a determination is made as to whether the primary pressure is less than the upper limit and greater than or equal to the lower limit of the diagnostic primary pressure. If the primary pressure is less than the upper limit and greater than or equal to the lower limit of the diagnostic primary pressure, then in step S108, it is determined that the primary pressure sensor 71 is normal, and the process is then temporarily terminated. On the other hand, if the primary pressure is greater than or equal to the upper limit or less than the lower limit of the diagnostic primary pressure, then in step S110, it is determined that the primary pressure sensor 71 has an abnormal characteristic, and the process is then temporarily terminated.

As described above in detail, according to this embodiment, when a predetermined diagnostic condition is satisfied and feedback control using the primary pressure is stopped, the clamping force ratio is calculated based on the gear ratio calculated from the ratio between the primary rotation speed and the secondary rotation speed, the input torque to the primary pulley 34, and the secondary pressure, and the upper and lower limits of the diagnostic primary pressure (i.e., the appropriate range of the primary pressure) for diagnosing the characteristic abnormality of the primary pressure sensor 71 are set based on the clamping force ratio and the secondary pressure. Then, when the primary pressure is less than the upper limit and greater than or equal to the lower limit of the diagnostic primary pressure (within the appropriate range), the primary pressure sensor 71 is determined to be normal, and when the primary pressure is greater than or equal to the upper limit or less than the lower limit of the diagnostic primary pressure (not within the appropriate range), the primary pressure sensor 71 is determined to be abnormal in characteristics. Therefore, for example, even in a hydraulic circuit 80 in which the primary pressure does not become zero when the ignition is off (when the engine is stopped), it is possible to detect an abnormality in the characteristics (rationality) of the primary pressure sensor 71. As a result, this embodiment makes it possible to detect abnormalities in the characteristics (rationality) of the primary pressure sensor 71, regardless of the configuration of the hydraulic circuit that adjusts the primary pressure.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, the hydraulic circuit to which the continuously variable transmission abnormality detection device 1 according to the present invention is applied is not limited to the one shown in FIG. 3 (hydraulic circuit 80).

In addition, in the above embodiment, the present invention is applied to a chain-type continuously variable transmission 30, but instead of the chain-type continuously variable transmission 30, the present invention can also be applied to, for example, a belt-type continuously variable transmission, etc.

Furthermore, the system configuration is not limited to the above embodiment. For example, in the above embodiment, the ECU 60 that controls the engine 10 and the TCU 40 that controls the continuously variable transmission 30 are configured as separate hardware, but they may be configured as integrated hardware.

REFERENCE SIGNS LIST 1 Continuously variable transmission abnormality detection device 10 Engine 20 Torque converter 30 Continuously variable transmission 34 Primary pulley 35 Secondary pulley 36 Chain 40 TCU
50 Valve body (control valve)
57 Primary rotation speed sensor 58 Secondary rotation speed sensor 60 ECU
61 Air flow meter 62 Accelerator pedal sensor 71 Primary pressure sensor 72 Secondary pressure sensor 80 Hydraulic circuit 81 Upshift solenoid 82 Downshift solenoid 83 Upshift valve 84 Downshift valve 100 CAN

Claims (5)

a primary pressure sensor for detecting a primary pressure, which is a hydraulic pressure value of oil supplied to the primary pulley;
a secondary pressure sensor for detecting a secondary pressure, which is a hydraulic pressure value of oil supplied to the secondary pulley;
a primary rotation speed sensor for detecting a primary rotation speed, which is the rotation speed of the primary pulley;
a secondary rotation speed sensor that detects a secondary rotation speed, which is the rotation speed of the secondary pulley;
a control unit that controls a gear ratio by adjusting the hydraulic pressure of the oil supplied to the primary pulley and the hydraulic pressure of the oil supplied to the secondary pulley,
The control unit includes:
When a predetermined diagnosis condition is satisfied and the feedback control using the primary pressure is stopped,
a clamping force ratio is calculated based on a speed ratio calculated from a ratio between the primary rotation speed and the secondary rotation speed, an input torque to the primary pulley, and the secondary pressure, and an upper limit value and a lower limit value of a diagnostic primary pressure for diagnosing a characteristic abnormality of the primary pressure sensor are set based on the clamping force ratio and the secondary pressure;
an abnormality detection device for a continuously variable transmission, the device determining that the primary pressure sensor is normal when the primary pressure is less than an upper limit value and greater than or equal to a lower limit value of the primary pressure for diagnosis, and determining that the primary pressure sensor has an abnormality in characteristics when the primary pressure is greater than or equal to the upper limit value or less than the lower limit value of the primary pressure for diagnosis. The control unit includes:
a clamping force ratio upper limit map that defines a relationship between the gear ratio, a torque ratio that is a ratio between a torque transmittable by a variator and an input torque, and an upper limit value of the clamping force ratio, and a clamping force ratio lower limit map that defines a relationship between the gear ratio, the torque ratio, and a lower limit value of the clamping force ratio,
searching the clamping force ratio upper limit map and the clamping force ratio lower limit map using the gear ratio and the torque ratio to obtain the upper limit value of the clamping force ratio and the lower limit value of the clamping force ratio;
2. The abnormality detection device for a continuously variable transmission according to claim 1, wherein an upper limit value and a lower limit value of the diagnostic primary pressure are set based on the upper limit value of the clamping force ratio, the lower limit value of the clamping force ratio, and the secondary pressure. 3. The abnormality detection device for a continuously variable transmission according to claim 2, wherein the control unit sets an upper limit value of the diagnostic primary pressure based on the following equation (1), and sets a lower limit value of the diagnostic primary pressure based on the following equation (2).
Primary pressure upper limit for diagnosis = {clamping force ratio upper limit map (gear ratio, torque ratio) search value × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area ... (1)
Primary pressure lower limit for diagnosis = {clamping force ratio lower limit map (gear ratio, torque ratio) search value x (secondary pressure x secondary cylinder pressure area)} / primary cylinder pressure area ... (2) The continuously variable transmission abnormality detection device according to claim 3, characterized in that the control unit sets the upper and lower limits of the diagnostic primary pressure taking into account the detection variation of the secondary pressure sensor. The abnormality detection device for a continuously variable transmission according to any one of claims 1 to 4, characterized in that the control unit determines that the predetermined diagnostic condition is met when the change in the secondary pressure, the change in the gear ratio, and the change in the input torque are each within a predetermined range.

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