JP6673693B2 - Control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission.

  As a transmission mounted on a vehicle, a belt-type CVT (Continuously Variable Transmission) is widely known.

  The belt-type CVT has a configuration in which an endless belt is wound around a primary pulley on the input side and a secondary pulley on the output side. Each of the primary pulley and the secondary pulley includes a fixed sheave, and a movable sheave that faces the fixed sheave with a belt therebetween and is movable in the facing direction (axial direction).

  By controlling the supply of oil to the movable sheave of the primary pulley, the distance between the fixed sheave and the movable sheave of the primary pulley is changed. Along with this, the winding diameter of the belt around the primary pulley changes, the distance between the fixed sheave and the movable sheave of the secondary pulley changes, and the winding diameter of the belt around the secondary pulley changes. Thus, the gear ratio (pulley ratio) continuously changes in a stepless manner.

  On the other hand, the belt-type CVT is configured to transmit power from the primary pulley to the secondary pulley by contact frictional force between each pulley and the belt. Therefore, it is necessary to apply a squeezing pressure corresponding to the input torque to the belt from each pulley. Therefore, for example, the clamping pressure is set by multiplying the minimum clamping pressure that can prevent the belt from slipping with respect to the input torque by a predetermined safety factor, and the secondary pulley is set so that the set clamping pressure is obtained. The hydraulic pressure supplied to the movable sheave is controlled.

JP 2015-194169 A

  However, when the belt is suddenly braked by an inertia torque, the squeezing pressure applied to the belt (belt squeezing pressure) may be insufficient, and the belt may slip. When the pulley is abnormally worn due to the slipping of the belt and the frictional resistance between the belt and the pulley is reduced, the belt easily slips on the pulley. If the safety factor when setting the pinching pressure is set to a large value to prevent the belt from slipping, the pinching pressure will be excessive, and overload will be applied to each part (such as the bearing that supports the pulley). Causes an increase in energy loss.

  An object of the present invention is to provide a control device for a belt continuously variable transmission that can appropriately suppress occurrence of belt slippage.

  To achieve the above object, a control device for a continuously variable transmission according to the present invention is a control device for a belt-type continuously variable transmission having a configuration in which an endless belt is wound around a pulley, Detecting means for detecting a slip of the belt with respect to the belt, state obtaining means for obtaining a state of the pulley with respect to detection of belt slip by the slip detecting means, and storage for storing the state of the pulley obtained by the state obtaining means. Means, and fail-safe execution means for executing fail-safe for suppressing occurrence of belt slippage based on the state of the pulley stored in the storage means.

  According to this configuration, when the belt slides on the pulley, the state of the pulley is acquired and stored in the storage unit. Then, based on the state of the pulley stored in the storage means, a failsafe for suppressing the occurrence of belt slippage is executed. Since the failsafe is executed based on the state of the pulley that has a correspondence with the occurrence of the slip of the belt, the occurrence of the slip of the belt can be appropriately suppressed.

  The state acquiring means acquires a gear ratio corresponding value corresponding to the gear ratio of the continuously variable transmission when the slip detection of the belt is detected by the slip detecting means as the state of the pulley, and the fail-safe execution means acquires fail-safe as a fail safe. When the speed ratio of the stepped transmission is within a predetermined range including a speed ratio corresponding to the speed ratio corresponding value stored in the storage means, the clamping force applied to the belt is increased, or The configuration may be limited.

  Thus, when the speed ratio of the continuously variable transmission is within a predetermined range including the speed ratio at the time of occurrence of slippage of the belt, the clamping pressure applied to the belt is increased, or the speed ratio is configured. Therefore, the occurrence of slip of the belt can be satisfactorily suppressed. In addition, since repeated slippage of the belt while the belt is in contact with the same location on the pulley can be suppressed, a decrease in the coefficient of friction due to abnormal wear at that location can be suppressed. In addition, since the pinching pressure is limitedly increased, it is possible to suppress an overload from being applied to each part as compared with a method of increasing the pinching pressure regardless of the gear ratio, and to increase the energy loss in each part. Can be suppressed.

  The state acquiring means acquires, as the state of the pulley, a friction coefficient corresponding value corresponding to a friction coefficient between the pulley and the belt when the slip detection of the belt is detected by the slip detecting means. As a safe, the clamping pressure applied to the belt may be increased according to the friction coefficient corresponding value stored in the storage means.

  By increasing the squeezing pressure applied to the belt in accordance with the friction coefficient corresponding value acquired when the belt slips, the occurrence of the belt slip can be favorably suppressed. In addition, since repeated slippage of the belt while the belt is in contact with the same location on the pulley can be suppressed, a decrease in the coefficient of friction due to abnormal wear at that location can be suppressed.

  The gear ratio corresponding value may be a value of the gear ratio itself, or may be a diameter of a belt wound around a pulley corresponding to the gear ratio.

  The value corresponding to the friction coefficient may be a value of the friction coefficient itself between the pulley and the belt.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a belt slip can be suppressed appropriately.

It is a figure showing composition of an important section of a vehicle in which a control device concerning one embodiment of the present invention was carried. FIG. 2 is a skeleton diagram showing a configuration of a drive system of the vehicle. 9 is a flowchart illustrating a flow of a μ map creation process. It is a figure showing an example of a μ map. It is a figure showing other examples of a μ map.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Main components of the vehicle>
FIG. 1 is a diagram illustrating a configuration of a main part of a vehicle 1 on which a control device according to an embodiment of the present invention is mounted.

  The vehicle 1 is an automobile driven by the engine 2. The output of the engine 2 is transmitted to left and right drive wheels of the vehicle 1 via a torque converter 3 and a continuously variable transmission (CVT) 4.

  The engine 2 is provided with an electronic throttle valve for adjusting the amount of intake air into the combustion chamber of the engine 2, an injector (fuel injection device) for injecting fuel into intake air, a spark plug for generating electric discharge in the combustion chamber, and the like. Have been. In addition, the engine 2 is provided with a starter for starting the engine.

  The vehicle 1 is provided with a plurality of ECUs (Electronic Control Units) including a CPU, a ROM, a RAM, and the like. The plurality of ECUs include an engine ECU 11 and a CVT ECU 12. Each ECU is connected to be capable of bidirectional communication by a CAN (Controller Area Network) communication protocol.

  An accelerator sensor 21 and an engine speed sensor 22 are connected to the engine ECU 11.

  The accelerator sensor 21 outputs a detection signal corresponding to the operation amount of the accelerator pedal operated by the driver. Based on the detection signal input from the accelerator sensor 21, the engine ECU 11 sets the ratio of the operation amount to the maximum operation amount of the accelerator pedal, that is, 0% when the accelerator pedal is not depressed, and depresses the accelerator pedal to the maximum. Then, the accelerator opening degree, which is a percentage with respect to the time of 100%, is calculated.

  The engine speed sensor 22 outputs a pulse signal synchronized with the rotation of the engine 2 (the rotation of the crankshaft) as a detection signal. The engine ECU 11 converts the frequency of the pulse signal input from the engine speed sensor 22 into the speed of the engine 2 (engine speed).

  The engine ECU 11 is provided in the engine 2 for starting, stopping, adjusting output, and the like based on information obtained from detection signals of various sensors and / or various information input from other ECUs. It controls electronic throttle valves, injectors and spark plugs.

  The CVT ECU 12 is connected with a primary rotation speed sensor 23, a secondary rotation speed sensor 24, a hydraulic pressure sensor 25, and the like.

  Primary rotation speed sensor 23 outputs, for example, a pulse signal synchronized with the rotation of primary shaft 51 (see FIG. 2) of continuously variable transmission 4 as a detection signal. The CVT ECU 12 converts the frequency of the pulse signal input from the primary rotation speed sensor 23 into the rotation speed of the primary shaft 51 (primary rotation speed).

  Secondary rotation speed sensor 24 outputs, for example, a pulse signal synchronized with the rotation of secondary shaft 52 (see FIG. 2) of continuously variable transmission 4 as a detection signal. The CVT ECU 12 converts the frequency of the pulse signal input from the secondary rotation speed sensor 24 into the rotation speed of the secondary shaft 52 (secondary rotation speed).

  The hydraulic pressure sensor 25 outputs a detection signal corresponding to the hydraulic pressure acting on the movable sheave 66 (see FIG. 2) of the secondary pulley 54 of the continuously variable transmission 4. The CVT ECU 12 obtains the hydraulic pressure acting on the movable sheave 66 from the detection signal of the hydraulic pressure sensor 25.

  The CVT ECU 12 controls each part of the continuously variable transmission 4 based on information obtained from detection signals of various sensors and / or various information input from other ECUs, for example, to control the speed of the continuously variable transmission 4. It controls various valves included in a hydraulic circuit 26 for supplying hydraulic pressure.

<Configuration of drive system>
FIG. 2 is a skeleton diagram illustrating a configuration of a drive system of the vehicle 1.

  The torque converter 3 includes a pump impeller 31, a turbine runner 32, and a lock-up clutch 33. The output shaft (E / G output shaft) of the engine 2 is connected to the pump impeller 31. The pump impeller 31 is provided so as to be integrally rotatable about the same rotation axis as the E / G output shaft. ing. The turbine runner 32 is provided rotatable about the same rotation axis as the pump impeller 31. The lock-up clutch 33 is provided for directly connecting / disconnecting the pump impeller 31 and the turbine runner 32. When the lock-up clutch 33 is engaged, the pump impeller 31 and the turbine runner 32 are directly connected. When the lock-up clutch 33 is released, the pump impeller 31 and the turbine runner 32 are separated.

  When the E / G output shaft is rotated in a state where the lock-up clutch 33 is released, the pump impeller 31 rotates. When the pump impeller 31 rotates, oil flows from the pump impeller 31 to the turbine runner 32. This oil flow is received by the turbine runner 32, and the turbine runner 32 rotates. At this time, an amplifying action of the torque converter 3 occurs, and a power larger than the power (torque) of the E / G output shaft is generated in the turbine runner 32.

  In a state where the lock-up clutch 33 is engaged, when the E / G output shaft is rotated, the E / G output shaft, the pump impeller 31 and the turbine runner 32 rotate integrally.

  An oil pump 5 is provided between the torque converter 3 and the continuously variable transmission 4. The oil pump 5 is a mechanical oil pump, and the pump shaft is arranged so that the rotation axis coincides with the pump impeller 31, and is connected to the pump impeller 31 so as not to rotate relatively. Thus, when the pump impeller 31 is rotated by the power of the engine 2, the pump shaft of the oil pump 5 rotates, and oil is discharged from the oil pump 5.

  The continuously variable transmission 4 transmits power input from the torque converter 3 to the differential gear 6. The continuously variable transmission 4 includes an input shaft 41, an output shaft 42, a belt transmission mechanism 43, and a forward / reverse switching mechanism 44.

  The input shaft 41 is connected to the turbine runner 32 of the torque converter 3, and is provided so as to be integrally rotatable about the same rotation axis as the turbine runner 32.

  The output shaft 42 is arranged parallel to the input shaft 41. An output gear 45 is supported by the output shaft 42 so as not to rotate relatively.

  The belt transmission mechanism 43 includes a primary shaft 51 and a secondary shaft 52. The primary shaft 51 and the secondary shaft 52 are arranged on the same axis as the input shaft 41 and the output shaft 42, respectively.

  The belt transmission mechanism 43 has a configuration in which an endless belt 55 is wound around a primary pulley 53 supported on a primary shaft 51 and a secondary pulley 54 supported on a secondary shaft 52.

  The primary pulley 53 is opposed to a fixed sheave 61 fixed to the primary shaft 51 with a belt 55 interposed between the fixed sheave 61 and a movable sheave supported on the primary shaft 51 so as to be movable in its axial direction and relatively non-rotatable. 62. A piston 63 fixed to the primary shaft 51 is provided on a side opposite to the fixed sheave 61 with respect to the movable sheave 62, and a piston chamber (oil chamber) 64 is formed between the movable sheave 62 and the piston 63. I have.

  The secondary pulley 54 is opposed to a fixed sheave 65 fixed to the secondary shaft 52 with the belt 55 interposed therebetween, and is supported by the secondary shaft 52 so as to be movable in the axial direction and relatively non-rotatable. And a movable sheave 66. A piston 67 fixed to the secondary shaft 52 is provided on the opposite side of the movable sheave 66 from the fixed sheave 65, and a piston chamber 68 is formed between the movable sheave 66 and the piston 67.

  Although not shown, a bias spring for applying an initial clamping pressure (initial thrust) to the belt 55 is interposed between the movable sheave 66 and the piston 67. The movable sheave 66 and the piston 67 are urged away from each other by the elastic force of the bias spring.

  The forward / reverse switching mechanism 44 is interposed between the input shaft 41 and the primary shaft 51 of the belt transmission mechanism 43. The forward / reverse switching mechanism 44 includes a planetary gear mechanism 71, a reverse clutch C1, and a forward brake B1.

  The planetary gear mechanism 71 includes a carrier 72, a sun gear 73, and a ring gear 74.

  The carrier 72 is fitted on the input shaft 41 so as to be relatively rotatable. The carrier 72 rotatably supports a plurality of pinion gears 75. The plurality of pinion gears 75 are arranged on the circumference.

  The sun gear 73 is supported by the input shaft 41 so as not to rotate relatively, and is arranged in a space surrounded by the plurality of pinion gears 75. The gear teeth of the sun gear 73 mesh with the gear teeth of each pinion gear 75.

  The ring gear 74 is provided such that its rotation axis coincides with the axis of the primary shaft 51. The primary shaft 51 of the belt transmission mechanism 43 is connected to the ring gear 74. The gear teeth of the ring gear 74 are formed so as to enclose the plurality of pinion gears 75 collectively, and mesh with the gear teeth of each pinion gear 75.

  The reverse clutch C1 is switched by an oil pressure between an engaged state (on) in which the carrier 72 and the sun gear 73 are directly connected (integrally rotatable) and a released state (off) in which the direct connection is released.

  The forward brake B1 is provided between the carrier 72 and a transmission case accommodating the torque converter 3 and the continuously variable transmission 4. The forward brake B1 controls the engagement state (ON) of braking the carrier 72 by hydraulic pressure and the rotation of the carrier 72. The state is switched to an allowable release state (off).

  When the vehicle 1 moves forward, the reverse clutch C1 is released and the forward brake B1 is engaged. When the power of the engine 2 is input to the input shaft 41, the sun gear 73 rotates integrally with the input shaft 41 with the carrier 72 stationary. Therefore, the rotation of the sun gear 73 is transmitted to the ring gear 74 in the reverse direction and at a reduced speed. Accordingly, the ring gear 74 rotates, and the primary shaft 51 and the primary pulley 53 of the belt transmission mechanism 43 rotate integrally with the ring gear 74. The rotation of the primary pulley 53 is transmitted to the secondary pulley 54 via the belt 55, and rotates the secondary pulley 54 and the secondary shaft 52. Then, the output shaft 42 and the output gear 45 rotate integrally with the secondary shaft 52. The output gear 45 meshes with the differential gear 6 (input gear of the differential gear 6). When the output gear 45 rotates, the drive shafts 7, 8 extending left and right from the differential gear 6 rotate, and the vehicle 1 moves forward by rotating drive wheels (not shown).

  On the other hand, when the vehicle 1 is moving backward, the reverse clutch C1 is engaged, and the forward brake B1 is released. When the power of the engine 2 is input to the input shaft 41, the carrier 72 and the sun gear 73 rotate integrally with the input shaft 41. Therefore, the rotation of the sun gear 73 is transmitted to the ring gear 74 without the rotation direction being reversed. As a result, the ring gear 74 rotates in a direction opposite to the direction in which the vehicle 1 advances, and the primary shaft 51 and the primary pulley 53 of the belt transmission mechanism 43 rotate integrally with the ring gear 74. The rotation of the primary pulley 53 is transmitted to the secondary pulley 54 via the belt 55, and rotates the secondary pulley 54 and the secondary shaft 52. Then, the output shaft 42 and the output gear 45 rotate integrally with the secondary shaft 52. When the output gear 45 rotates, the drive shafts 7, 8 extending left and right from the differential gear 6 rotate in the opposite direction to the forward movement, and the drive wheels (not shown) rotate, so that the vehicle 1 moves backward.

<Μ map creation processing>
FIG. 3 is a flowchart showing the flow of the μ map creation processing.

  While the engine 2 is operating, the CVT ECU 12 executes the μ map creation processing shown in FIG.

  In the μ map creating (updating) process, it is determined whether or not slippage of the belt 55 with respect to the secondary pulley 54 has been detected (step S1). For example, if the primary rotational speed rises rapidly and the primary rotational speed after the rapid rise is maintained for a predetermined time or more, slippage of the belt 55 with respect to the secondary pulley 54 is detected, and it is determined that slippage of the belt 55 has been detected. Is done.

  Until the slip of the belt 55 is detected (NO in step S1), the subsequent processing is not executed.

  When slippage of the belt 55 is detected (YES in step S1), a friction coefficient μ between the secondary pulley 54 and the belt 55 is estimated (step S2). When estimating the friction coefficient μ, the input torque input to the continuously variable transmission 4, the thrust of the secondary pulley 54, and the winding diameter of the belt 55 around the secondary pulley 54 are obtained. Then, the friction coefficient μ is estimated from the input torque, the thrust and the winding diameter.

  The input torque is calculated by multiplying the engine torque by the torque ratio of the torque converter 3. The engine torque is, for example, estimated from the accelerator opening and the engine speed by the engine ECU 11 and transmitted from the engine ECU 11 to the CVT ECU 12. The torque ratio is a torque amplification rate according to the speed ratio of the torque converter 3. The speed ratio is a value obtained by dividing the turbine speed by the engine speed.

  The thrust of the secondary pulley 54 is calculated by multiplying the secondary hydraulic pressure by the pressure receiving area of the movable sheave 66 of the secondary pulley 54 and adding the multiplied value to the centrifugal hydraulic pressure acting on the movable sheave 66 and the initial thrust by the bias spring. . The pressure receiving area of the movable sheave 66 and the initial thrust by the bias spring are known, and are stored in the nonvolatile memory of the CVT ECU 12. The centrifugal oil pressure acting on the movable sheave 66 is obtained by multiplying a predetermined oil density stored in the non-volatile memory of the CVT ECU 12 by a square value of the secondary rotation speed, and multiplying the multiplied value according to the specifications of the continuously variable transmission 4. It is obtained by further multiplying by the set coefficient.

  The winding diameter is a value determined by the speed ratio γ (the pulley ratio of the primary pulley 53 and the secondary pulley 54). The gear ratio γ can be obtained from the primary rotation speed and the secondary rotation speed.

  After the estimation of the friction coefficient μ, the estimated friction coefficient μ and the gear ratio γ at the time of the estimation of the friction coefficient μ are associated with each other and stored in a rewritable nonvolatile memory (flash memory or EEPROM, etc.) of the CVT ECU 12. (Step S3).

<Μ map>
FIG. 4 is a diagram illustrating an example of the μ map. FIG. 5 is a diagram showing another example of the μ map.

  The μ map maps the relationship between the gear ratio γ and the friction coefficient μ. The μ map is stored in the rewritable nonvolatile memory of the CVT ECU 12 from the beginning, and when the slip of the belt 55 is detected and the friction coefficient μ and the gear ratio γ are obtained, the friction coefficient μ and the gear ratio are obtained. By updating the μ map using the ratio γ, the friction coefficient μ and the speed ratio γ are stored in the nonvolatile memory (μ map).

Specifically, in the μ map at the initial stage, the secondary pulley 54 and the belt 55 are provided for each speed ratio γ that differs by a fixed difference α between the minimum value γ _min and the maximum value γ _max of the speed ratio γ. constant value mu _B is stored is a specification value of the friction coefficient mu between. And slippage of the belt 55 is detected, for example, the low friction coefficient mu _L are obtained with gamma gear ratio than its predetermined value mu _B, in mu map, the acquired transmission ratio a predetermined range including a gamma (e.g. , The lower limit of the speed ratio “γ _min + N · α (N: an integer of 0 or more)” and the upper limit of the speed ratio “γ _min + (N + M) · α (M: an integer of 1 or more)”. friction coefficient corresponding to each gear ratio gamma mu is rewritten to the obtained friction coefficient mu _L.

<Hydraulic control>
In the continuously variable transmission 4, the movable sheave 62 (piston chamber 64) of the primary pulley 53 and the movable sheave 66 (piston) of the secondary pulley 54 are controlled by the CVT ECU 12 from the hydraulic circuit 26 so as to achieve a gear ratio corresponding to the accelerator opening and the vehicle speed. The hydraulic pressure supplied to the chamber 68) is controlled (shift control).

  When the gear ratio γ is reduced, the hydraulic pressure supplied to the movable sheave 62 of the primary pulley 53 is increased. Thereby, the movable sheave 62 moves to the fixed sheave 61 side, and the interval (groove width) between the fixed sheave 61 and the movable sheave 62 is reduced. Along with this, the winding diameter of the belt 55 around the primary pulley 53 increases, and the distance (groove width) between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 increases. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 decreases, and the speed ratio γ decreases.

  When the gear ratio γ is increased, the hydraulic pressure supplied to the movable sheave 62 of the primary pulley 53 is reduced. As a result, the thrust of the secondary pulley 54 on the belt 55 becomes larger than the thrust of the primary pulley 53 on the belt 55, the distance between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 becomes smaller, and the fixed sheave 61 and the movable sheave The distance from the gap 62 increases. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 increases, and the speed ratio γ of the continuously variable transmission 4 increases.

  On the other hand, the clamping pressure between the primary pulley 53 and the secondary pulley 54 needs to be large enough to prevent slippage between the primary pulley 53 and the secondary pulley 54 and the belt 55. Therefore, the hydraulic pressure supplied to the movable sheave 66 of the secondary pulley 54 is controlled so that a clamping pressure corresponding to the magnitude of the input torque input to the input shaft 41 is obtained (clamping pressure control).

In this pinching pressure control, a μ map is used. That is, the CVT ECU 12 refers to the μ map and acquires the friction coefficient μ corresponding to the speed ratio γ configured by the speed change control. When the friction coefficient μ corresponding to the gear ratio γ is shown in the μ map, the friction coefficient μ is read from the μ map. When the friction coefficient μ corresponding to the speed ratio γ is not shown in the μ map, the friction coefficient μ corresponding to the speed ratio γ is obtained by interpolation from the values shown in the μ map. Then, it is determined whether the friction coefficient obtained from mu map mu is or lower than the predetermined value mu _B is, as shown in FIG. 4, when the friction coefficient mu is less than a predetermined value mu _B is input The hydraulic pressure supplied to the movable sheave 66 of the secondary pulley 54 is controlled such that a clamping pressure increased by a predetermined amount from a clamping pressure corresponding to the magnitude of the torque is obtained. In other words, it is read range of the speed ratio γ that corresponds to a low friction coefficient mu than the predetermined value mu _B from mu map, if included gear ratio γ is constituted by shift control within its scope, the input torque The hydraulic pressure supplied to the movable sheave 66 of the secondary pulley 54 is controlled such that a clamping pressure that is increased by a predetermined amount from the clamping pressure corresponding to the magnitude of is obtained. The predetermined amount may be a fixed amount, or may be set to an amount corresponding to the friction coefficient μ, for example, a larger amount as the friction coefficient μ is smaller. When the friction coefficient μ is used for the pinching pressure calculation, when the friction coefficient μ obtained from the μ map decreases, the pinching pressure naturally increases in accordance with the friction coefficient μ in the pinching pressure calculation.

The μ map is also used in the shift control. That is, by CVTECU12, are referenced mu map, whether relation of mu mapped to the threshold mu _th following friction coefficient mu and the gear ratio γ is shown is examined. Then, when the relationship is shown in mu mapped to the threshold mu _th following friction coefficient mu and the gear ratio gamma, the shift control, configuring the speed ratio gamma corresponding to the threshold mu _th following friction coefficient mu Is forbidden.

<Effects>
As described above, when the belt 55 slides on the secondary pulley 54, the friction coefficient μ between the secondary pulley 54 and the belt 55 is obtained by estimation as an example of the state of the secondary pulley 54. Then, the gear ratio γ at the time of acquisition of the friction coefficient μ is associated with and stored in the μ map.

  Based on the friction coefficient μ stored in the μ map, a fail safe for suppressing the occurrence of slippage of the belt 55 is executed.

If this as a fail-safe, it is read range of the speed ratio γ that corresponds to a low friction coefficient mu than the predetermined value mu _B from mu map, contained the gear ratio γ is constituted by shift control within its scope, The hydraulic pressure supplied to the movable sheave 66 of the secondary pulley 54 is controlled such that a clamping pressure increased by a predetermined amount from the clamping pressure corresponding to the magnitude of the input torque is obtained.

The coefficient of friction is obtained in the event of slippage of the belt 55 mu, is lower than a predetermined value mu _B, the speed ratio γ that corresponds to a low friction coefficient mu than the predetermined value mu _B, in the event of slippage of the belt 55 Corresponds to the gear ratio γ. If the gear ratio composed of a shift control γ is in the range of the speed ratio γ corresponding to mu lower coefficient of friction than the predetermined value mu _B, since clamping pressure applied to the belt 55 is increased, the belt 55 The occurrence of slippage can be suppressed. In addition, since slippage of the belt 55 can be suppressed from occurring repeatedly while the belt 55 is in contact with the same location on the secondary pulley 54, a decrease in the friction coefficient μ due to abnormal wear at that location can be suppressed. In addition, since the pinching pressure is limitedly increased, overload can be suppressed from being applied to each part as compared with the method of increasing the pinching pressure regardless of the gear ratio γ, and the energy loss in each part can be reduced. The increase can be suppressed.

Further, as another fail-safe, when the μ map shows the relationship between the friction coefficient μ equal to or less than the threshold _μth and the gear ratio γ, the friction coefficient μ equal to or less than the threshold _μth is an abnormal value. In the control, it is prohibited to configure the speed ratio γ corresponding to the friction coefficient μ equal to or smaller than the threshold value _μth .

By speed ratio corresponding to the threshold mu _th following friction coefficient mu gamma is not configured, it is possible to suppress the occurrence of slippage of belt 55. In addition, since slippage of the belt 55 can be suppressed from occurring repeatedly while the belt 55 is in contact with the same location on the secondary pulley 54, a decrease in the friction coefficient μ due to abnormal wear at that location can be suppressed.

<Modification>
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented in another form.

  For example, the μ map is obtained by mapping the relationship between the gear ratio γ and the friction coefficient μ. However, since there is a certain relationship between the gear ratio γ and the diameter of the belt 55 wrapped around the secondary pulley 54, the μ map shows the relationship between the diameter of the belt 55 wrapped around the secondary pulley 54 and the friction coefficient μ. It may be a map. In this case, when the μ map is used, the winding diameter of the belt 55 around the secondary pulley 54 may be calculated from the speed ratio γ configured by the speed change control.

Further, in the speed change control, it is prohibited to configure the speed ratio γ corresponding to the friction coefficient μ equal to or smaller than the threshold value _μth . However, when a configuration is adopted in which the clamping pressure is increased by an amount corresponding to the friction coefficient μ in the clamping pressure control, the speed control corresponding to the friction coefficient μ in which the increasing amount of the clamping pressure is equal to or more than a predetermined amount is performed in the shift control. Configuring γ may be prohibited.

  The speed ratio γ may be acquired in response to the occurrence of the slippage of the belt 55, and the speed change control may be prohibited from configuring the speed ratio γ at which the slippage of the belt 55 has occurred a predetermined number of times or more. In addition, the amount of heat given to the secondary pulley 54 due to the slippage of the belt 55 is acquired, and the amount of heat is stored in the non-volatile memory of the CVT ECU 12 in association with the speed ratio γ at the time of the slippage. Then, in the shift control, it may be prohibited to configure the speed ratio γ associated with the heat amount equal to or more than the predetermined amount. Further, in order to prevent insufficient driving force at the time of starting, when the sheave input torque is small, the prohibition of the configuration of the speed ratio γ may be temporarily released.

  Each of the above-described sensors is merely an example of a sensor related to the present invention, and other sensors may be connected to the engine ECU 11 and the CVT ECU 12.

  Some or all of the functions of the engine ECU 11 and the CVT ECU 12 may be integrated into one ECU.

  Although the continuously variable transmission 4 has been described, the control device according to the present invention can also use the control device according to the present invention for a power split type continuously variable transmission. The power split type continuously variable transmission includes a belt-type continuously variable transmission mechanism that continuously changes the power by changing the speed ratio, and a constant transmission mechanism that changes the power at a constant speed ratio. Can be divided into two systems and transmitted.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

4 continuously variable transmission 12 CVT ECU (control device, slip detection means, state acquisition means, storage means, fail-safe execution means)
54 Secondary pulley 55 Belt

Claims (2)

A belt-type continuously variable transmission control device having a configuration in which an endless belt is wound around a pulley,
Slip detecting means for detecting slip of the belt with respect to the pulley,
State acquisition means for acquiring the state of the pulley with respect to the detection of the slip of the belt by the slip detection means,
Storage means for storing the state of the pulley acquired by the state acquisition means,
Fail-safe execution means for executing fail-safe for suppressing occurrence of slippage of the belt based on the state of the pulley stored in the storage means,
The state obtaining means obtains, as the state of the pulley, a gear ratio corresponding value corresponding to a gear ratio of the continuously variable transmission when the slip detection of the belt is detected by the slip detecting means,
The fail-safe executing means, when the speed ratio of the continuously variable transmission is within a predetermined range including a speed ratio corresponding to a speed ratio corresponding value stored in the storage means, as the fail-safe, or to increase the clamping pressure applied to, or to limit the configuration of the gear ratio, the control apparatus. A belt-type continuously variable transmission control device having a configuration in which an endless belt is wound around a pulley,
Slip detecting means for detecting slip of the belt with respect to the pulley,
State acquisition means for acquiring the state of the pulley with respect to the detection of the slip of the belt by the slip detection means,
Storage means for storing the state of the pulley acquired by the state acquisition means,
Fail-safe execution means for executing fail-safe for suppressing occurrence of slippage of the belt based on the state of the pulley stored in the storage means,
The state acquisition unit acquires, as the state of the pulley, a friction coefficient corresponding value corresponding to a friction coefficient between the pulley and the belt when the slip detection unit detects slippage of the belt,
The failsafe execution unit, as the fail-safe, to increase the clamping pressure applied to the belt in accordance with the friction coefficient corresponding value stored in the storage means, the control apparatus.

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