Continuously variable transmission abnormal detection device

Abstract

To provide a continuously variable transmission abnormality detection device capable of detecting abnormality in primary pressure sensor characteristics even though having a configuration of a hydraulic circuit adjusting primary pressure.SOLUTION: A TCU 40: obtains a transmission gear ratio which is a ratio of a primary rotation speed to a secondary rotation speed and a clamp force ratio on the basis of input torque to a primary pulley 34 and secondary pressure when a predetermined diagnosis condition is met with feedback control using primary pressure stopped; sets an upper limit and a lower limit of diagnosis primary pressure to diagnose abnormality in characteristics of a primary pressure sensor 71 on the basis of the clamp force ratio and the secondary pressure; determines that the primary pressure sensor 71 is in a normal state when the primary pressure is less than the upper limit of the diagnosis primary pressure and equal to or higher than the lower limit thereof; and determines that the primary pressure sensor 71 has characteristic abnormality when the primary pressure is equal to or higher than the upper limit of the diagnosis primary pressure or less than the lower limit thereof.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an abnormality detection device for a continuously variable transmission, and more particularly, to an abnormality detection device for a continuously variable transmission that detects an abnormal characteristic of a primary pressure sensor that detects a hydraulic pressure value of oil supplied to a primary pulley that constitutes the continuously variable transmission.

Background Art

[0002] In recent years, as a vehicle automatic transmission, a continuously variable transmission (CVT) such as a chain type or a belt type that can change the transmission ratio steplessly, has no shift shock, and can improve fuel consumption has been widely put into practical use. 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 wound around these pulleys. The engine torque generated by the engine is transmitted from the primary pulley to the secondary pulley through a power transmission element such as a chain. Further, the continuously variable transmission changes the transmission ratio steplessly by changing the groove width of each pulley to change the winding diameter of the power transmission element.

[0003] Here, the clamping force (pulley side pressure) applied to each of the primary pulley and the secondary pulley is controlled 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, respectively. At this time, in the control unit, feedback (F / B) control is performed so that the target hydraulic pressure obtained based on the operating state matches the actual hydraulic pressure detected by the hydraulic pressure sensor.

[0004] In addition, in order to perform feedback control appropriately, a primary pressure sensor that detects the primary pressure, which is the hydraulic pressure value of the oil supplied to the primary pulley, and an abnormality of the secondary pressure sensor that detects the secondary pressure, which is the hydraulic pressure value of the oil supplied to the secondary pulley, for example, an abnormality in the open mode (open circuit abnormality), an abnormality in the short mode (short circuit abnormality), an abnormality in sticking (abnormality of continuously outputting a constant value), etc. are detected (fault diagnosis) (see, for example, Patent Document 1).

[0005] Furthermore, for example, a method has been proposed for detecting that the sensor characteristics are abnormal, 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).

[0006] More specifically, as such a method for detecting characteristic abnormalities (diagnosis method), for example, when the ignition is turned off (engine stopped) and the hydraulic feedback control is stopped, the fact that the actual hydraulic pressure becomes 0 MPa is utilized, and based on whether the sensor value is near 0 MPa at that time (whether it outputs an appropriate range of voltage values, etc.), a method for determining (detecting) whether the characteristics of the sensor are abnormal has been proposed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, depending on the configuration of the hydraulic circuit that adjusts the primary pressure, for example, when the line pressure drops after ignition off (engine stop), the hydraulic pressure for operating the downshift valve that lowers the primary pressure becomes insufficient, and the downshift valve cannot be operated as instructed, and the primary pressure may not be able to be lowered to 0 MPa. Thus, in the case of a hydraulic circuit in which the primary pressure cannot be zeroed at ignition off (engine stop), for example, there has been a problem that the above-described abnormality detection method cannot detect an abnormality in the characteristics (rationality) of the primary pressure sensor.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide an abnormality detection device for a continuously variable transmission that can detect an abnormality in the characteristics of a primary pressure sensor regardless of the configuration of a hydraulic circuit that adjusts the primary pressure (for example, even in a hydraulic circuit in which the primary pressure does not become zero at ignition off (engine stop)).

Means for Solving the Problems

[0010] The abnormal 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 transmission 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 respectively. When a predetermined diagnostic condition is satisfied and the feedback control using the primary pressure is stopped, the control unit obtains a clamp force ratio based on the transmission ratio obtained from the ratio of the primary rotation speed and the secondary rotation speed, the input torque to the primary pulley, and the secondary pressure, sets an upper limit value and a lower limit value of a diagnostic primary pressure for diagnosing a characteristic abnormality of the primary pressure sensor based on the clamp force ratio and the secondary pressure, and determines that the primary pressure sensor is normal when the primary pressure is less than the upper limit value and not less than the lower limit value of the diagnostic primary pressure, and determines that the primary pressure sensor has a characteristic abnormality when the primary pressure is not less than the upper limit value or less than the lower limit value of the diagnostic primary pressure.

[0011] According to the abnormal detection device for a continuously variable transmission according to the present invention, when a predetermined diagnosis condition is satisfied and the feedback control using the primary pressure is stopped, a clamping force ratio is obtained based on the speed ratio obtained from the ratio of the primary rotational speed and the secondary rotational 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 value and a lower limit value of the diagnostic primary pressure (that is, an appropriate range of the primary pressure) for diagnosing a characteristic abnormality of the primary pressure sensor are set. When the primary pressure is less than the upper limit value and not less than the lower limit value of the diagnostic primary pressure (when it is within the appropriate range), it is determined that the primary pressure sensor is normal. When the primary pressure is not less than the upper limit value or less than the lower limit value of the diagnostic primary pressure (when it is not within the appropriate range), it is determined that the primary pressure sensor has a characteristic abnormality. 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 stops), it is possible to detect a characteristic (rationality) abnormality of the primary pressure sensor.

Effect of the Invention

[0012] According to the present invention, 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 (when the engine stops)), it is possible to detect a characteristic (rationality) abnormality of the primary pressure sensor.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0014] 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 descriptions will be omitted.

[0015] First, with reference to FIGS. 1 and 2 together, the configuration of the abnormality detection device 1 for a continuously variable transmission according to the embodiment will be described. FIG. 1 is a block diagram showing the configuration of the abnormality detection device 1 for a continuously variable transmission and a continuously variable transmission 30 etc. to which the abnormality detection device 1 for the continuously variable transmission is applied. FIG. 2 is a diagram showing an example of a hydraulic circuit 80 for adjusting the primary pressure.

[0016] The engine 10 may be of any type, for example, a horizontally opposed in-cylinder injection type 4-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 also 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 61. 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. Also, a spark plug for igniting the air-fuel mixture and an in-ignitor 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.

[0017] In addition to the above-described air flow meter 61 and throttle opening sensor 14, a cam angle sensor for determining 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. Further, various sensors such as an accelerator pedal sensor 62 for detecting the amount of depression of the accelerator pedal, that is, the operation amount 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.

[0018] To the output shaft 15 of the engine 10, a continuously variable transmission 30 that converts and outputs the driving force from the engine 10 via a torque converter 20 having a clutch function and a torque amplification function is connected.

[0019] The torque converter 20 mainly includes a pump impeller 21, a turbine runner 22, and a stator 23. The pump impeller 21 connected to the output shaft 15 generates an oil flow, and the turbine runner 22 disposed opposite to the pump impeller 21 receives the power of the engine 10 via the oil and drives the output shaft. The stator 23 positioned between the two rectifies the discharge flow (return) from the turbine runner 22 and returns it to the pump impeller 21 to generate a torque amplification effect.

[0020] 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 (in the 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. When the lock-up clutch 24 is engaged (during lock-up), the driving force of the engine 10 is directly transmitted to the continuously variable transmission 30. The rotational speed of the turbine runner 22 that constitutes the torque converter 20 (turbine rotational speed) is detected by a turbine rotational speed sensor 56. The detected turbine rotational speed is output to a transmission control unit (hereinafter referred to as "TCU") 40, which will be described later.

[0021] The continuously variable transmission 30 has a primary shaft 32 connected to the output shaft 25 of the torque converter 20 via a reduction gear 31 (or a forward / reverse switching mechanism), and a secondary shaft 37 disposed parallel to the primary shaft 32.

[0022] A primary pulley 34 is provided on the primary shaft 32. The primary pulley 34 has a fixed sheave 34a joined to the primary shaft 32 and a movable sheave 34b that is 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 and 34b, that is, the pulley groove width, can be changed. On the other hand, a secondary pulley 35 is provided on the secondary shaft 37. The secondary pulley 35 has a fixed sheave 35a joined to the secondary shaft 37 and a movable sheave 35b that is 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.

[0023] A chain 36 for transmitting driving force is stretched between the primary pulley 34 and the 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 around the respective pulleys 34, 35 (pulley ratio), the gear ratio is continuously changed. The power transmission mechanism composed 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. Also, if the rotational speed of the primary pulley 34 is Np and the rotational speed of the secondary pulley 35 is Ns, the gear ratio i is expressed as i = Np / Ns.

[0024] Here, a hydraulic chamber (hydraulic cylinder chamber) 34c is formed in the primary pulley 34 (movable sheave 34b). On the other hand, 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, "the clamping force Fp of the primary pulley 34 = primary pressure Pp × pressure receiving area of the hydraulic chamber 34c" and "the clamping force Fs of the secondary pulley 35 = secondary pressure Ps × pressure receiving area of the hydraulic chamber 35c". Also, the ratio (Fp / Fs) of the primary pulley clamping force Fp to the secondary pulley clamping force Fs is called the clamping force ratio.

[0025] The hydraulic pressure for shifting the continuously variable transmission 30, that is, the primary pressure and the secondary pressure described above, is regulated by a valve body (control valve) 50. The valve body 50 opens and closes an oil passage formed in the valve body 50 by using a plurality of spool valves and a solenoid valve (electromagnetic valve) that moves the spool valve, adjusts the hydraulic pressure discharged from the oil pump, and supplies it to the hydraulic pressure chamber 34c of the primary pulley 34 and the hydraulic pressure chamber 35c of the secondary pulley 35. Further, the valve body 50 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 pressure chamber 35c of the secondary pulley 35 is adjusted according to the transmission torque required for the chain 36. Further, the primary pressure supplied to the hydraulic pressure chamber 34c of the primary pulley 34 is adjusted to a value according to the target gear ratio or the like. Note that the valve body 50 supplies hydraulic pressure to, for example, a forward / reverse switching mechanism that switches the forward and reverse of the vehicle.

[0026] Here, on the floor or center console of the vehicle, etc., there is provided a shift lever (select lever) 51 that receives an operation by the driver to selectively switch between an automatic transmission mode ("D" range) and a manual transmission mode ("M" range). A range switch 59 that is connected to move in conjunction with the shift lever 51 and detects the selected position of the shift lever 51 is attached to 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. Note that the shift lever 51 can selectively switch between a parking "P" range, a reverse "R" range, a neutral "N" range, in addition to the "D" range and the "M" range.

[0027] An M range switch 52 that turns on when the shift lever 51 is positioned on the M range side, that is, when the manual transmission mode is selected, and turns off when the shift lever 51 is positioned on the D range side, that is, when the automatic transmission mode is selected, is incorporated in the shift lever 51. The M range switch 52 is also connected to the TCU 40.

[0028] On the other hand, on the rear side of the steering wheel 53, there are provided a plus (+) paddle switch 54 and a minus (-) paddle switch 55 for receiving a shifting operation (shifting request) by the driver during the manual shift mode (hereinafter, the plus paddle switch 54 and the minus paddle switch 55 may be 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.

[0029] 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 by the TCU 40. Also, connected to the TCU 40 are a primary rotation speed sensor 57 for detecting the rotation speed of the primary pulley 34 and a secondary rotation speed sensor 58 for detecting the rotation speed of the secondary pulley 35. Further, connected to the TCU 40 are also a primary pressure sensor 71 for detecting the pressure (hydraulic pressure) of the oil supplied to the primary pulley 34 and a secondary pressure sensor 72 for detecting the pressure (hydraulic pressure) of the oil supplied to the secondary pulley 35.

[0030] As described above, the continuously variable transmission 30 is provided with two shift modes that can be selectively switched by operating the shift lever 51, namely, an automatic shift mode and a manual shift mode. The automatic shift mode is selected by operating the shift lever 51 to the D range, and is a mode in which the gear ratio is automatically changed according to the driving state of the vehicle. The manual shift mode is selected by operating the shift lever 51 to the M range, and is a mode in which the gear ratio is switched according to the driver's shifting operation (operation of the paddle switches 54, 55).

[0031] The clamp force control and shift control of the continuously variable transmission 30 are 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, 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, and changing the clamp force and the gear ratio of the continuously variable transmission 30. That is, the TCU 40 functions as a control unit described in the claims.

[0032] Here, FIG. 2 shows a hydraulic circuit 80 that is configured inside the valve body 50 and adjusts (up-shift / down-shift) the primary pressure.

[0033] The up-shift solenoid 81 adjusts the pilot pressure created from the line pressure according to the duty ratio applied from the TCU 40 to generate an up-shift control pressure. The generated up-shift control pressure is supplied to the up-shift valve 83 via the up-shift control pressure oil passage 91. Note that, as the up-shift solenoid 81, for example, a duty solenoid whose opening degree is adjusted according to the duty ratio is preferably used. The up-shift solenoid 81 is controlled by the TCU 40.

[0034] The up-shift valve 83 is connected to the line pressure oil passage 90, the up-shift control pressure oil passage 91, and the primary pressure oil passage 93. Inside the up-shift valve 83, a spool 83a is slidably accommodated in the axial direction. A spring 83b is disposed at the end of the spool 83a. The spool 83a is driven in the axial direction according to the balance between the pushing force (up-shift control pressure × pressure receiving area) by the up-shift control pressure generated by the up-shift solenoid 81 and the spring force (biasing force) of the spring 83b. Thus, during up-shifting, the line pressure is adjusted according to the up-shift control pressure to generate an up-shift hydraulic pressure. The generated up-shift hydraulic pressure is supplied to the primary pulley 34 (hydraulic chamber 34c) via the primary pressure oil passage 93. As a result, the gear ratio is up-shifted.

[0035] On the one hand, the downshift solenoid 82 regulates the pilot pressure created from the line pressure according to the duty ratio applied from the TCU 40 to generate a downshift control pressure. The generated downshift control pressure is supplied to the downshift valve 84 via the downshift control pressure oil passage 92. As the downshift solenoid 82, for example, a duty solenoid whose opening degree is adjusted according to the duty ratio is preferably used. The downshift solenoid 82 is controlled by the TCU 40.

[0036] The downshift valve 84 is connected to the primary pressure oil passage 93, the downshift control pressure oil passage 92, and the drain oil passage 94. When downshifting, the downshift valve 84 discharges oil from the primary pulley 34 (hydraulic chamber 34c) to the drain oil passage 94 according to the downshift control pressure. As a result, the gear ratio is downshifted. Here, in the hydraulic circuit 80, when the line pressure drops after ignition is turned off (after the engine stops), the hydraulic pressure for operating the downshift valve 84 that lowers the primary pressure becomes insufficient, and the downshift valve 84 cannot be operated as instructed, and the primary pressure cannot be lowered to 0 MPa.

[0037] Returning to FIG. 1, the TCU 40 is communicably connected to the ECU 60 that comprehensively controls the engine 10 and the like via the CAN (Controller Area Network) 100.

[0038] The TCU 40 and the ECU 60 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, and an input / output I / F and the like.

[0039] In the ECU 60, the cylinder is discriminated from the output of the cam angle sensor, and the engine speed is obtained from the change in the rotational position of the crankshaft detected by the output of the crank angle sensor. Also, in the ECU 60, various information such as the intake air amount, accelerator pedal operation amount, 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. Further, in the ECU 60, for example, the engine torque of the engine 10 is calculated based on the engine speed and the intake air amount. Here, the engine torque of the engine 10 can be obtained, for example, by previously storing a map (engine torque map) that defines the relationship between the engine speed, the intake air amount, and the engine torque, and searching the engine torque map. Then, the ECU 60 comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices based on these various pieces of information acquired. 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.

[0040] The TCU 40 receives various information such as the engine speed, accelerator pedal operation amount, and engine torque (i.e., the variator input torque) transmitted from the ECU 60. Also, the TCU 40 receives, for example, vehicle speed information detected by a wheel speed sensor etc. through the CAN 100.

[0041] Then, the TCU 40 drives the upshift solenoid 81 and the downshift solenoid 82 according to the shift map based on the various information acquired from the various sensors etc. described above. Thereby, the gear ratio is automatically and steplessly shifted according to the driving state of the vehicle (for example, the accelerator pedal operation amount and vehicle speed etc.). Note that the shift map is stored in the EEPROM etc. inside the TCU 40. Also, the TCU 40 adjusts the clamping force (pulley side pressure) of the secondary pulley 35 based on the engine torque of the engine 10 received from the ECU 60 via the CAN 100.

[0042] In particular, regardless of the configuration of the hydraulic circuit that adjusts the primary pressure (for example, even in the case of a hydraulic circuit 80 where the primary pressure does not become zero when the ignition is off (engine stopped)), the TCU 40 has a function of detecting an abnormality in the characteristics (rationality) of the primary pressure sensor 71. In the TCU 40, this function is realized by a program stored in the EEPROM being executed by the microprocessor.

[0043] When a predetermined diagnostic condition is satisfied and the feedback control using the primary pressure is stopped, the TCU 40 obtains a ratio of the transmission ratio obtained from the ratio of the primary rotational speed and the secondary rotational speed, the torque transmissible by the variator (determined by the transmission ratio of the variator and the clamping force of the variator (secondary pulley pressure)), and the torque ratio which is the ratio of the variator input torque, and based on this torque ratio, obtains a clamping force ratio which is the ratio of the clamping force of the primary pulley 34 and the clamping force of the secondary pulley 35, and based on the clamping force ratio and the secondary pressure, sets an upper limit value and a lower limit value of the diagnostic primary pressure for diagnosing an abnormality in the characteristics (rationality) of the primary pressure sensor 71.

[0044] Then, when a state where the primary pressure is less than the upper limit value and not less than the lower limit value of the diagnostic primary pressure has elapsed for a predetermined time (for example, 1 second) or more, the TCU 40 determines that the primary pressure sensor 71 is normal. On the other hand, when a state where the primary pressure is not less than the upper limit value or less than the lower limit value of the diagnostic primary pressure has elapsed for a predetermined time (for example, 1 second) or more, the TCU 40 determines that the primary pressure sensor 71 has an abnormal characteristic.

[0045] At that time, for example, when the vehicle speed is equal to or higher than a predetermined value (e.g., 10 km / h), and each of the changes (change speed, change amount) in the target secondary pressure, the change (change speed, change amount) in the target gear ratio, and the change (change speed, change amount) in the input torque (accelerator pedal operation amount) is within a predetermined range for a predetermined time (e.g., 1 second) or more (that is, when it is substantially constant and stable), the TCU 40 determines that a predetermined diagnostic condition is satisfied. As the predetermined diagnostic condition, for example, it may be added that no failure (abnormality) that stops the diagnosis has occurred, the deviation between the target secondary pressure and the actual secondary pressure is equal to or less than a predetermined value, the deviation between the target gear ratio and the actual gear ratio is equal to or less than a predetermined value, the actual line pressure is equal to or less than a predetermined value, the engine water temperature is equal to or higher than a predetermined value, it is in the D range (forward driving range), the actual gear ratio is within a predetermined range, etc.

[0046] More specifically, the TCU 40 stores in advance in an EEPROM or the like a clamp force ratio upper limit value map that defines the relationship between the gear ratio and the upper limit value of the torque ratio, which is the ratio of the torque that can be transmitted by the variator and the variator input torque, and the clamp force ratio. The TCU 40 searches the clamp force ratio upper limit value map using the gear ratio and the torque ratio to obtain the upper limit value of the clamp force ratio. Then, the TCU 40 sets the upper limit value of the primary pressure for diagnosis based on the upper limit value of the clamp force ratio and the secondary pressure.

[0047] Similarly, the TCU 40 stores in advance in an EEPROM or the like a clamp force ratio lower limit value map that defines the relationship between the gear ratio, the torque ratio, and the lower limit value of the clamp force ratio. The TCU 40 searches the clamp force ratio lower limit value map using the gear ratio and the torque ratio to obtain the lower limit value of the clamp force ratio. Then, the TCU 40 sets the lower limit value of the primary pressure for diagnosis based on the lower limit value of the clamp force ratio and the secondary pressure.

[0048] Here, an example of the clamp force ratio upper limit value 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 clamp force ratio upper limit value map, the upper limit value of the clamp force ratio (a value considering the variation (upper limit)) is given for each combination (lattice point) of the torque ratio and the gear ratio. Note that in the clamp force ratio upper limit value map, the upper limit value of the clamp force ratio increases as the torque ratio increases, and also the upper limit value of the clamp force ratio increases as the gear ratio decreases. Note that the clamp force ratio lower limit value map is the same as the clamp force ratio upper limit value map except that a value considering the variation (lower limit) is set, so detailed description is omitted here.

[0049] More specifically, the TCU 40 sets the upper limit value of the diagnostic primary pressure based on the following equation (1). Upper limit value of diagnostic primary pressure = {Search value of clamp force ratio upper limit value map (gear ratio, torque ratio) × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area ··· (1) Note that data based on design specifications and the like for the secondary cylinder pressure receiving area and the primary cylinder pressure receiving area are stored in advance in a memory or the like.

[0050] Similarly, the TCU 40 sets the lower limit value of the diagnostic primary pressure based on the following equation (2). Lower limit value of diagnostic primary pressure = {Search value of clamp force ratio lower limit value map (gear ratio, torque ratio) × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area ··· (2)

[0051] At that time, it is preferable for the TCU 40 to set the upper limit value and the lower limit value of the diagnostic primary pressure respectively in consideration of the detection variation of the secondary pressure sensor 72.

[0052] Next, while referring to FIG. 4, the operation of the continuously variable transmission abnormality detection device 1 will be described. FIG. 4 is a flowchart showing the processing procedure of the characteristic abnormality detection process by the continuously variable transmission abnormality detection device 1. This process is repeatedly executed in the TCU 40 at predetermined time intervals (for example, every 10 ms).

[0053] In step S100, the primary rotational speed, the secondary rotational speed, the primary pressure, the secondary pressure, etc. are read. Subsequently, in step S102, it is determined whether or not a predetermined diagnostic condition (including that the feedback control using the primary pressure has stopped) is satisfied. Here, if the predetermined diagnostic condition is not satisfied, the process exits temporarily from this process. On the other hand, if the predetermined diagnostic condition is satisfied, the process proceeds to step S104. Note that since the predetermined diagnostic condition is as described above, a detailed description thereof is omitted here.

[0054] In step S104, the upper limit value and the lower limit value of the diagnostic primary pressure for diagnosing the characteristic (rationality) abnormality of the primary pressure sensor 71 are set. Note that since the method of setting the upper limit value and the lower limit value of the diagnostic primary pressure is as described above, a detailed description thereof is omitted here.

[0055] Next, in step S106, it is determined whether or not 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. Here, if 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, in step S108, it is determined that the primary pressure sensor 71 is normal, and then the process exits temporarily from this process. On the other hand, if 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, in step S110, it is determined that the primary pressure sensor 71 has a characteristic abnormality, and then the process exits temporarily from this process.

[0056] As described in detail above, according to this embodiment, when a predetermined diagnostic condition is satisfied and the feedback control using the primary pressure is stopped, the clamping force ratio is obtained based on the speed ratio obtained from the ratio between the primary rotational speed and the secondary rotational speed, and the input torque to the primary pulley 34 and the secondary pressure. Based on the clamping force ratio and the secondary pressure, the upper limit value and the lower limit value of the diagnostic primary pressure (that is, the appropriate range of the primary pressure) for diagnosing the characteristic abnormality of the primary pressure sensor 71 are set. When the primary pressure is less than the upper limit value and not less than the lower limit value of the diagnostic primary pressure (when it is within the appropriate range), it is determined that the primary pressure sensor 71 is normal. When the primary pressure is not less than the upper limit value or less than the lower limit value of the diagnostic primary pressure (when it is not within the appropriate range), it is determined that the primary pressure sensor 71 has a characteristic abnormality. 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 stops), it is possible to detect the characteristic (rationality) abnormality of the primary pressure sensor 71. As a result, according to this embodiment, regardless of the configuration of the hydraulic circuit that adjusts the primary pressure, it is possible to detect the characteristic (rationality) abnormality of the primary pressure sensor 71.

[0057] 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, 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).

[0058] Further, in the above embodiment, the present invention is applied to the chain type continuously variable transmission 30. However, instead of the chain type continuously variable transmission 30, for example, it can also be applied to a belt type continuously variable transmission or the like.

[0059] 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 with separate hardware, but they may be configured with integrated hardware.

Explanation of Reference Numerals

[0060] 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

1. 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; A control unit that controls the transmission 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 respectively; and The control unit: When a predetermined diagnostic condition is satisfied and the feedback control using the primary pressure is stopped, Obtains a clamping force ratio based on the transmission ratio obtained from the ratio of the primary rotation speed to the secondary rotation speed, the input torque to the primary pulley, and the secondary pressure, and based on the clamping force ratio and the secondary pressure, sets an upper limit value and a lower limit value of a diagnostic primary pressure for diagnosing a characteristic abnormality of the primary pressure sensor; When the primary pressure is less than the upper limit value and not less than the lower limit value of the diagnostic primary pressure, it is determined that the primary pressure sensor is 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, it is determined that the primary pressure sensor has a characteristic abnormality. An abnormality detection device for a continuously variable transmission characterized by this.

2. The control unit: Pre-stores a clamping force ratio upper limit value map that defines the relationship between the transmission ratio, the torque ratio which is the ratio of the torque that can be transmitted by the variator to the input torque, and the upper limit value of the clamping force ratio, and a clamping force ratio lower limit value map that defines the relationship between the transmission ratio, the torque ratio, and the lower limit value of the clamping force ratio; Searches the clamping force ratio upper limit value map and the clamping force ratio lower limit value map respectively using the transmission 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; The abnormality detection device for a continuously variable transmission according to claim 1, wherein the upper limit value and the lower limit value of the diagnostic primary pressure are set respectively based on the upper limit value and 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 formula (1) and sets a lower limit value of the diagnostic primary pressure based on the following formula (2). Upper limit value of diagnostic primary pressure = {Search value of the maximum clamping force ratio map (transmission ratio, torque ratio) × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area... (1) Lower limit value of diagnostic primary pressure = {Search value of the minimum clamping force ratio map (transmission ratio, torque ratio) × (secondary pressure × secondary cylinder pressure receiving area)} / primary cylinder pressure receiving area... (2)

4. The abnormality detection device for a continuously variable transmission according to claim 3, wherein the control unit sets the upper limit value and the lower limit value of the diagnostic primary pressure respectively in consideration of the detection variation of the secondary pressure sensor.

5. The abnormality detection device for a continuously variable transmission according to any one of claims 1 to 4, wherein the control unit determines that the predetermined diagnostic condition is satisfied when each of the change in the secondary pressure, the change in the transmission ratio, and the change in the input torque is within a predetermined range.

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