JP6552334B2 - Control device of power split type continuously variable transmission - Google Patents

Description

  The present invention relates to a control device of a power split type continuously variable transmission capable of dividing and transmitting power input to an input shaft (input shaft) into two systems.

  As a transmission mounted on a vehicle such as an automobile, there is a continuously variable transmission mechanism for continuously changing the power of the engine, a gear mechanism for transmitting the power of the engine without passing through the continuously variable transmission mechanism, and a continuously variable transmission mechanism It has been proposed to have a planetary gear mechanism for combining the power from the gear and the power from the gear mechanism. In this transmission, the power from the engine can be divided into the continuously variable transmission mechanism and the gear mechanism, and each divided power can be synthesized by the planetary gear mechanism and transmitted to the wheels.

JP, 2004-176890, A

  The applicant has also proposed a transmission capable of dividing and transmitting the power of the drive source into two systems as a power split type continuously variable transmission.

  The power split type continuously variable transmission according to this proposal includes a continuously variable transmission mechanism, a parallel shaft gear mechanism and a planetary gear mechanism. The continuously variable transmission mechanism has the same configuration as a known belt-type continuously variable transmission (CVT). The power of the engine input to the input shaft is transmitted to the primary shaft of the continuously variable transmission mechanism. The secondary shaft of the continuously variable transmission mechanism is connected to the sun gear of the planetary gear mechanism. The parallel shaft gear mechanism includes a split drive gear to which the power of the input shaft is transmitted / interrupted, and a split driven gear which forms a gear train with the split drive gear and which rotates integrally with a carrier of the planetary gear mechanism. An output shaft is connected to the ring gear of the planetary gear mechanism. The rotation of the output shaft is transmitted to the differential gear and transmitted from the differential gear to the left and right drive wheels.

  The power split continuously variable transmission has a belt mode and a split mode as a power transmission mode in the forward range.

  In the belt mode, the sun gear and the ring gear of the planetary gear mechanism are directly connected. Further, by interrupting the transmission of power from the input shaft to the split drive gear, the split drive gear is brought into free rotation (free), and the carrier of the planetary gear mechanism is brought into free rotation. Therefore, the sun gear and the ring gear rotate integrally and the output shaft rotates integrally with the ring gear by the power output from the continuously variable transmission mechanism. Therefore, in the belt mode, the gear ratio (unit gear ratio) of the power split continuously variable transmission matches the gear ratio (belt gear ratio) of the continuously variable transmission mechanism.

  In the split mode, the direct connection between the sun gear and the ring gear is released. Further, power is transmitted from the input shaft to the split drive gear, and the power is accelerated at a constant gear ratio (split gear ratio) by the split drive gear via the split driven gear, and is input to the carrier of the planetary gear mechanism. The Therefore, if the rotational speed input to the input shaft is constant, the rotational speed of the carrier is kept constant. Therefore, when the belt gear ratio is increased and the rotational speed of the sun gear is decreased, the rotational speed of the ring gear and the output shaft connected to the ring gear is increased, and the unit gear ratio is decreased. Therefore, in the split mode, the unit gear ratio becomes equal to or less than the split gear ratio.

  Further, in the reverse range (reverse range), the direct connection between the sun gear and the ring gear is released, the transmission of power from the input shaft to the split drive gear is interrupted, and the carrier is fixed by the engagement of the engagement elements. Therefore, when the sun gear rotates by the power output from the continuously variable transmission mechanism, the output shaft rotates integrally with the ring gear in the direction opposite to the rotation direction of the sun gear. At this time, due to the configuration of the planetary gear mechanism, the rotational speed of the ring gear is always lower than the rotational speed of the sun gear.

  Therefore, the maximum value of the unit gear ratio at reverse (maximum reverse gear ratio) is larger than the maximum value of the unit gear ratio at forward movement (maximum forward gear ratio), and the reverse of the engine compared to that at forward The driving force output to the output shaft is large due to torque control creep during idling. Therefore, in the reverse range, measures such as reducing the belt speed ratio are necessary.

  However, when being shifted to the reverse range, it is also necessary to engage an engagement element (brake) for fixing the carrier. Therefore, the pulley of the continuously variable transmission mechanism and the engagement element for changing the belt transmission ratio and engaging the engagement element when the engine speed is idle and the discharge flow rate of the oil pump is small. It must supply hydraulic pressure to the

  On the other hand, in the engagement control of the engagement element, for example, learning for stabilizing the piston stroke time with individual variation is performed. That is, in the engagement control of the engagement element, from the start of supply of hydraulic pressure to the engagement element to the number of rotations of the input shaft of the power split type continuously variable transmission (number of rotations of the turbine runner of the torque converter) The piston stroke time is measured, and learning such as oil pressure supplied to the engagement element is performed so that the measured piston stroke time approaches the target time. As this learning progresses, the occurrence of shift shock due to individual variation in piston stroke time is suppressed.

  However, when shifting to the reverse range, oil must be supplied to the pulleys and engaging elements of the continuously variable transmission mechanism when the discharge flow rate of the oil pump is small, so the oil supplied to the engaging elements Flow rate is not stabilized, and learning for stabilizing the piston stroke time may be erroneous.

  An object of the present invention is to control a power split type continuously variable transmission capable of suppressing reverse driving force (driving force output to an output shaft at the time of reverse operation) while suppressing erroneous learning in engagement control of engagement elements. It is providing a device.

  In order to achieve the above object, a control device for a power split type continuously variable transmission according to the present invention includes an input shaft to which power is input, an output shaft that outputs power, and power is transmitted from the input shaft. Continuously variable transmission comprising a primary shaft, a primary pulley supported by the primary shaft, a secondary shaft provided parallel to the primary shaft, a secondary pulley supported by the secondary shaft, and a belt wound around the primary pulley and the secondary pulley A planetary gear mechanism including a carrier, a sun gear provided integrally with the secondary shaft, and a ring gear provided rotatably with the output shaft, and a split drive gear for transmitting / shutting off the power of the input shaft, And a split drive gear and a gear train that rotate integrally with the carrier A control device for controlling a power split type continuously variable transmission including a parallel shaft type gear mechanism having a lit driven gear and an engagement element engaged / released by hydraulic pressure to prohibit / allow carrier rotation. A reverse instruction detection means for detecting a reverse instruction; an instruction value setting means for setting an instruction value for engagement control for engaging the engagement element in response to detection of the reverse instruction by the reverse instruction detection means; Learning means for learning the setting mode of the instruction value by the instruction value setting means based on the time from the detection of the reverse instruction by the reverse instruction detection means to the rotation number of the input shaft showing a predetermined change, and learning by the learning means Learning completion determination means for determining completion / incompleteness and learning completed by the learning completion determination means when the reverse instruction is detected by the reverse instruction detection means In the case of disconnection, in response to the detection of the reverse instruction, transmission ratio control for reducing the transmission ratio of the continuously variable transmission mechanism is executed, and it is determined that the learning is not completed by the learning completion determining means. And transmission ratio control means for suppressing execution of transmission ratio control.

  The reverse instruction is an instruction to shift to the reverse range. For example, in a vehicle provided with a shift lever, the shift lever is shifted to the reverse range (switched) by being operated to the reverse position (R position). ) Is instructed.

  According to this configuration, when the reverse instruction is issued, an instruction value for engagement control for engaging the engagement element is set, and the hydraulic pressure corresponding to the instruction value is supplied to the engagement element. When the engaging element is engaged by supplying hydraulic pressure, the carrier of the planetary gear mechanism of the power split type continuously variable transmission is stopped (rotation is prohibited). By stopping the carrier, the rotation direction of the ring gear of the planetary gear mechanism is reversed from the rotation direction of the sun gear, and a reverse range is configured.

  As the hydraulic pressure is supplied to the engagement element, the transmission torque capacity of the engagement element increases. When hydraulic pressure is supplied to the engagement element, a time until the rotational speed of the input shaft shows a predetermined change is acquired from the reverse instruction by the increase of the transfer torque capacity. Then, in the engagement control of the engagement element, the setting mode of the instruction value for controlling the hydraulic pressure supplied to the engagement element is learned based on the acquired time.

  In the reverse range, the reverse driving force becomes large, so it is desirable to reduce the gear ratio of the continuously variable transmission mechanism. However, when the setting ratio of the indication value is learned, if the gear ratio of the continuously variable transmission mechanism is changed, oil is supplied to the continuously variable transmission mechanism, and the flow rate of oil supplied to the engagement element is stabilized. There is a risk that learning will be false learning.

  Therefore, if it is determined that the learning is completed / not completed and the learning is not completed, the execution of the transmission ratio control to reduce the transmission ratio of the continuously variable transmission mechanism is suppressed. Thereby, false learning in engagement control of the engagement element can be suppressed. On the other hand, when learning is completed, it is not necessary to perform learning, and therefore gear ratio control for reducing the gear ratio of the continuously variable transmission mechanism is executed. By executing the transmission ratio control, the transmission ratio of the continuously variable transmission mechanism can be reduced, and the reverse driving force can be suppressed.

  When any one or more of the following conditions (1) to (4) are satisfied, the transmission ratio control means detects the reverse instruction by the reverse instruction detection means regardless of whether or not learning is completed. In response, speed ratio control for reducing the speed ratio of the continuously variable transmission mechanism may be executed.

(1) The rotation speed (engine rotation speed) of the engine of the vehicle on which the power split type continuously variable transmission is mounted is equal to or more than a predetermined rotation speed.
(2) The output torque (engine torque) of the engine of the vehicle on which the power split type continuously variable transmission is mounted is equal to or greater than a predetermined torque value.
(3) The temperature of the cooling water flowing through the engine of the vehicle on which the power split type continuously variable transmission is mounted is equal to or lower than a predetermined temperature.
(4) The oil temperature of the power split type continuously variable transmission is equal to or lower than a predetermined temperature.

  According to the present invention, it is possible to suppress reverse driving force while suppressing false learning in engagement control of the engagement element.

It is a figure showing composition of an important section of vehicles by 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 a vehicle. It is a figure which shows the state of the clutch at the time of forward movement of a vehicle, and reverse movement. It is an alignment chart which shows the relationship of the rotation speed (rotational speed) of the sun gear of a planetary gear mechanism, a carrier, and a ring gear. FIG. 7 is a diagram showing an example of a time change of a state of a reverse switch, a belt transmission ratio, a turbine rotational speed and a brake control pressure when the shift range is switched from a neutral range to a reverse range. It is a flowchart which shows the flow of the process for determining the start timing of gear ratio control. FIG. 8 is a skeleton diagram showing another configuration of the power split type continuously variable transmission. It is a figure which shows the state of the clutch in each power transmission mode in the power split type continuously variable transmission shown by FIG. 7, and a brake.

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

<Vehicle configuration>

  FIG. 1 is a view showing the configuration of the main part of a vehicle 1 equipped with a control device according to an embodiment of the present invention.

  The vehicle 1 is an automobile having an engine 2 as a drive source.

  The output of the engine 2 is transmitted to driving wheels (for example, left and right front wheels) of the vehicle 1 via the torque converter 3 and the power split type continuously variable transmission 4. The engine 2 is provided with a throttle valve for adjusting the amount of intake air to the combustion chamber of the engine 2 and an ignition plug for generating an electric discharge in the combustion chamber. The engine 2 is also provided with a starter for starting the engine 2.

  The vehicle 1 is provided with a plurality of ECUs (electronic control units) having a configuration including a CPU and a memory (ROM, RAM, flash memory, EEPROM, etc.). The ECU includes an engine ECU 11 and a transmission ECU 12. The plurality of ECUs are connected so as to enable two-way communication by a CAN (Controller Area Network) communication protocol.

  An engine speed sensor 13 and a water temperature sensor 14 are connected to the engine ECU 11.

  The engine speed sensor 13 inputs a pulse signal synchronized with the rotation of the engine 2 (rotation of the crankshaft) to the engine ECU 11. The engine ECU 11 converts the frequency of the pulse signal input from the engine speed sensor 13 into the speed of the engine 2 (engine speed).

  The water temperature sensor 14 detects the temperature of the cooling water flowing through the engine 2 and inputs a signal corresponding to the detected water temperature to the engine ECU 11.

  The engine ECU 11 is a throttle provided to the engine 2 for starting, stopping, and adjusting the output of the engine 2 based on numerical values obtained from signals input from various sensors and various information input from other ECUs, etc. Control valves and spark plugs.

  A reverse switch 15 and a turbine rotation speed sensor 16 are connected to the transmission ECU 12.

  The reverse switch 15 is a switch that is on when the shift lever (select lever) is at the reverse position and is off when the shift lever is at a position other than the reverse position. As positions of the shift lever, for example, a parking position (P position), a reverse position (R position), a neutral position (N position), and a drive position (D position) are provided. The parking position, reverse position, neutral position and drive position respectively correspond to parking range (parking range), reverse range (reverse range), neutral range (neutral range) and drive range (forward range) of the shift range. The shift lever can be shifted between the parking position, the reverse position, the neutral position and the drive position, and the shift operation can indicate a shift range shift (shift).

  The turbine speed sensor 16 inputs a pulse signal synchronized with the rotation of the turbine runner 32 (see FIG. 2) of the torque converter 3 to the transmission ECU 12. The transmission ECU 12 converts the frequency of the pulse signal input from the turbine rotation speed sensor 16 into a turbine rotation speed that is the rotation speed of the turbine runner 32.

  The transmission ECU 12 changes the transmission ratio of the power split-type continuously variable transmission 4 based on numerical values obtained from signals input from various sensors and various information input from other ECUs. A valve (not shown) included in a hydraulic circuit 17 for supplying hydraulic pressure to each part of the continuously variable transmission 4 is controlled. Further, the transmission ECU 12 controls the hydraulic pressure supplied to the clutches C1 and C2 and the brake B1 (see FIG. 2) by control of the valves included in the hydraulic circuit 17, and switches the drive range and the reverse range. Switch between belt mode and split mode.

  The hydraulic circuit 17 is supplied with hydraulic pressure generated by an oil pump (not shown). The oil pump is, for example, a mechanical oil pump that is driven by the power of the engine 2. The valves of the hydraulic circuit 17 include hydraulic control valves that adjust the hydraulic pressure supplied to the clutches C1 and C2 and the brake B1, respectively. As the hydraulic control valve, a valve capable of controlling the output hydraulic pressure by a current value, for example, a linear solenoid valve is used.

<Configuration of drive system>

  FIG. 2 is a skeleton diagram showing a configuration of a drive system of the vehicle 1.

  The engine 2 is provided with an E / G output shaft 21. The E / G output shaft 21 is rotated by the power generated by the engine 2.

  The torque converter 3 includes a pump impeller 31, a turbine runner 32, and a lockup clutch 33. The E / G output shaft 21 is connected to the pump impeller 31, and the pump impeller 31 is integrally rotatably provided around the same rotation axis as the E / G output shaft 21. The turbine runner 32 is rotatably provided about the same rotation axis as the pump impeller 31. The lockup clutch 33 is provided to connect / disconnect the pump impeller 31 and the turbine runner 32 directly. When the lockup clutch 33 is engaged, the pump impeller 31 and the turbine runner 32 are directly coupled, and when the lockup clutch 33 is released, the pump impeller 31 and the turbine runner 32 are separated.

  When the E / G output shaft 21 is rotated in a state where the lockup clutch 33 is released, the pump impeller 31 is rotated. When the pump impeller 31 rotates, a flow of oil from the pump impeller 31 toward the turbine runner 32 is generated. This oil flow is received by the turbine runner 32 and the turbine runner 32 rotates. At this time, the amplifying action of the torque converter 3 occurs, and the turbine runner 32 generates a power larger than the power (torque) of the E / G output shaft 21.

  With the lockup clutch 33 engaged, when the E / G output shaft 21 is rotated, the E / G output shaft 21, the pump impeller 31 and the turbine runner 32 rotate integrally.

  Power split type continuously variable transmission 4 transmits the power input from torque converter 3 to differential gear 6. The power split type continuously variable transmission 4 includes an input shaft 41, an output shaft 42, a continuously variable transmission mechanism 43, a reverse gear mechanism 44, a planetary gear mechanism 45, a split drive gear 46 and a split driven gear 47.

  The input shaft 41 is connected to the turbine runner 32 of the torque converter 3 and provided integrally rotatably around the same rotation axis as the turbine runner 32.

  The output shaft 42 is provided in parallel with the input shaft 41. An output gear 48 is supported on the output shaft 42 so as not to be relatively rotatable. The output gear 48 meshes with the differential gear 6 (the input gear of the differential gear 6).

  The continuously variable transmission mechanism 43 has the same configuration as a known belt-type continuously variable transmission (CVT). More specifically, the continuously variable transmission mechanism 43 includes a primary shaft 51, a secondary shaft 52 provided parallel to the primary shaft 51, a primary pulley 53 supported against relative rotation by the primary shaft 51, and a secondary shaft 52. , And a belt 55 wound around the primary pulley 53 and the secondary pulley 54.

  Primary pulley 53 is disposed opposite to fixed sheave 61 fixed to primary shaft 51 and fixed sheave 61 with belt 55 interposed therebetween, and movable sheave supported on primary shaft 51 so as to be movable in the axial direction and to be relatively non-rotatable. And 62. A cylinder (not shown) fixed to the primary shaft 51 is provided on the opposite side of the movable sheave 62 from the fixed sheave 61, and a piston chamber (oil chamber) is formed between the movable sheave 62 and the cylinder Has been.

  Secondary pulley 54 is disposed opposite to fixed sheave 65 fixed to secondary shaft 52 and fixed sheave 65 with belt 55 interposed therebetween, and movable sheave supported on secondary shaft 52 so as to be movable in the axial direction and to be relatively non-rotatable. It has 66 and. A cylinder (not shown) fixed to the secondary shaft 52 is provided on the opposite side of the movable sheave 66 with respect to the fixed sheave 65, and a piston chamber (oil chamber) is formed between the movable sheave 66 and the cylinder Has been.

  In the continuously variable transmission mechanism 43, the hydraulic pressure supplied to the piston chambers of the primary pulley 53 and the secondary pulley 54 is controlled to change the groove widths of the primary pulley 53 and the secondary pulley 54, whereby the continuously variable transmission mechanism The belt transmission ratio, which is the transmission ratio at 43, is continuously changed steplessly.

  Specifically, when the belt speed ratio is lowered, the hydraulic pressure supplied to the piston chamber of the primary pulley 53 is increased. As a result, the movable sheave 62 of the primary pulley 53 moves toward the fixed sheave 61, and the distance (groove width) between the fixed sheave 61 and the movable sheave 62 decreases. Along with this, the winding diameter of the belt 55 with respect to the primary pulley 53 is increased, and the distance (groove width) between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 is increased. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 is reduced, and the belt transmission ratio is reduced.

  When the belt transmission ratio is increased, the hydraulic pressure supplied to the piston chamber of the primary pulley 53 is reduced. As a result, the thrust of secondary pulley 54 relative to belt 55 becomes larger than the thrust of primary pulley 53 relative to belt 55, and the distance between fixed sheave 65 and movable sheave 66 of secondary pulley 54 becomes smaller, and fixed sheave 61 and movable sheave The distance to 62 increases. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 is increased, and the belt transmission ratio is increased.

  On the other hand, the thrust of 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 each piston chamber of the primary pulley 53 and the secondary pulley 54 is controlled so that a thrust according to the magnitude of the torque input to the input shaft 41 is obtained.

  The reverse gear mechanism 44 is configured to transmit the power input to the input shaft 41 to the primary shaft 51 by reversely rotating and decelerating. Specifically, the reverse gear mechanism 44 has a first gear 71 that is supported by the input shaft 41 so as not to rotate relative to the input shaft 41, and has a larger diameter and a larger number of teeth than the first gear 71, so And a second gear 72 that is supported and meshes with the first gear 71.

  The planetary gear mechanism 45 includes a sun gear 81, a carrier 82, and a ring gear 83. The sun gear 81 is supported by the secondary shaft 52 so as not to be relatively rotatable. The carrier 82 is fitted on the output shaft 42 so as to be relatively rotatable. The carrier 82 rotatably supports a plurality of pinion gears 84. The plurality of pinion gears 84 are disposed on the circumference and mesh with the sun gear 81. The ring gear 83 has an annular shape that collectively surrounds a plurality of pinion gears 84, and is engaged with each pinion gear 84 from the outside in the rotational radial direction of the secondary shaft 52. Further, an output shaft 42 is connected to the ring gear 83, and the ring gear 83 is integrally rotatably provided around the same rotation axis as the output shaft 42.

  The split drive gear 46 is fitted on the input shaft 41 so as to be relatively rotatable.

  The split driven gear 47 is provided so as to be integrally rotatable about the same rotation axis as the carrier 82 of the planetary gear mechanism 45. The split driven gear 47 is formed with a smaller diameter than the split drive gear 46 and has fewer teeth than the split drive gear 46.

  The power split type continuously variable transmission 4 includes clutches C1 and C2 and a brake B1.

  The clutch C1 is switched between an engaged state (on) in which the input shaft 41 and the split drive gear 46 are directly coupled (coupled integrally rotatably) and a released state (off) in which the direct coupling is released.

  The clutch C2 is switched between an engaged state (on) in which the sun gear 81 and the ring gear 83 of the planetary gear mechanism 45 are directly coupled (coupled integrally rotatably) and a released state (off) in which the direct coupling is released.

  The brake B1 is switched between an engaged state (on) for braking the carrier 82 of the planetary gear mechanism 45 and a released state (off) for allowing the carrier 82 to rotate.

<Power transmission mode>

  FIG. 3 is a diagram showing the states of the clutches C1 and C2 and the brake B1 when the vehicle 1 is moving forward and backward. In FIG. 3, "o" indicates that the clutches C1 and C2 and the brake B1 are in the engaged state. “X” indicates that the clutches C1 and C2 and the brake B1 are in the released state.

  FIG. 4 is an alignment chart showing the relationship between the rotational speeds (rotational speeds) of the sun gear 81, the carrier 82 and the ring gear 83 of the planetary gear mechanism 45.

  The power split type continuously variable transmission 4 has a belt mode and a split mode as a power transmission mode when the vehicle 1 moves forward.

  In the belt mode, as shown in FIG. 3, the clutch C1 and the brake B1 are released and the clutch C2 is engaged. As a result, the split drive gear 46 is disconnected from the input shaft 41, the carrier 82 of the planetary gear mechanism 45 becomes free (free rotation state), and the sun gear 81 and the ring gear 83 of the planetary gear mechanism 45 are directly connected.

  The power input to the input shaft 41 is reversed and decelerated by the reverse gear mechanism 44 and transmitted to the primary shaft 51 of the continuously variable transmission mechanism 43 to rotate the primary shaft 51 and the primary pulley 53. The rotation of the primary pulley 53 is transmitted to the secondary pulley 54 via the belt 55 to rotate the secondary pulley 54 and the secondary shaft 52. Since the sun gear 81 and the ring gear 83 of the planetary gear mechanism 45 are directly connected, the sun gear 81, the ring gear 83, and the output shaft 42 rotate together with the secondary shaft 52. Therefore, in the belt mode, as shown in FIG. 4, the unit transmission ratio, which is the transmission ratio of the power split continuously variable transmission 4 as a whole, matches the belt transmission ratio.

  In the split mode, as shown in FIG. 3, the clutch C1 is engaged, and the clutch C2 and the brake B1 are released. Thereby, the input shaft 41 and the split drive gear 46 are directly connected, the carrier 82 of the planetary gear mechanism 45 becomes free, and the sun gear 81 and the ring gear 83 of the planetary gear mechanism 45 are disconnected.

  Part of the power input to the input shaft 41 is reversed and decelerated by the reverse gear mechanism 44, transmitted to the primary shaft 51 of the continuously variable transmission mechanism 43, and transmitted from the primary shaft 51 to the primary pulley 53, the belt 55 and the secondary pulley. It is transmitted to the secondary shaft 52 via the 54 and transmitted to the sun gear 81 of the planetary gear mechanism 45. On the other hand, part of the power input to the input shaft 41 is accelerated from the split drive gear 46 via the split driven gear 47 and transmitted to the carrier 82 of the planetary gear mechanism 45.

  The split gear ratio, which is the gear ratio between the split drive gear 46 and the split driven gear 47, is constant and unchanged (fixed). Therefore, in the split mode, if the power input to the input shaft 41 is constant, the planetary gear mechanism The rotation of 45 carriers 82 is maintained at a constant speed. For this reason, when the belt speed ratio is increased, the rotational speed of the sun gear 81 of the planetary gear mechanism 45 decreases, and therefore, as indicated by the broken line in FIG. Goes up. As a result, in the split mode, the unit transmission ratio decreases as the belt transmission ratio increases.

  The rotation of the output shaft 42 in the belt mode and the split mode is transmitted to the differential gear 6 via the output gear 48. Thereby, the drive shafts 7 and 8 of the vehicle 1 rotate in the forward direction.

  In the reverse range for reversing the vehicle 1, as shown in FIG. 3, the clutches C1 and C2 are engaged and the brake B1 is released. Thereby, the split drive gear 46 is disconnected from the input shaft 41, the sun gear 81 and the ring gear 83 of the planetary gear mechanism 45 are disconnected, and the carrier 82 of the planetary gear mechanism 45 is braked.

  The power input to the input shaft 41 is reversed and decelerated by the reverse gear mechanism 44, transmitted to the primary shaft 51 of the continuously variable transmission mechanism 43, and transmitted from the primary shaft 51 through the primary pulley 53, the belt 55 and the secondary pulley 54. Then, the sun gear 81 of the planetary gear mechanism 45 is rotated integrally with the secondary shaft 52. Since the carrier 82 of the planetary gear mechanism 45 is braked, when the sun gear 81 rotates, the ring gear 83 of the planetary gear mechanism 45 rotates in the opposite direction to the sun gear 81. The rotational direction of the ring gear 83 is opposite to the rotational direction of the ring gear 83 at the time of forward movement (belt mode and split mode). Then, the output shaft 42 rotates integrally with the ring gear 83. The rotation of the output shaft 42 is transmitted to the differential gear 6 via the output gear 48. Thereby, the drive shafts 7 and 8 of the vehicle 1 rotate in the reverse direction.

<Reverse shift control>

  FIG. 5 is a view showing an example of the state of the reverse switch, the belt transmission ratio, the turbine rotational speed, and the time change of the brake control pressure when the shift range is switched from the neutral range to the reverse range.

  When the shift lever is shifted from the neutral position to the reverse position, the state of the reverse switch 15 is switched from off to on (time T1). Based on the fact that the state of the reverse switch 15 is switched from off to on, the transmission ECU 12 detects an instruction for switching (shift) from the neutral range to the reverse range by the shift operation. In response to the detection, the transmission ECU 12 executes engagement control for engaging the brake B1 and speed ratio control for reducing the belt speed ratio.

  In the engagement control, in response to an instruction to switch from the neutral range to the reverse range, the brake control pressure is raised to a backlash oil pressure higher than the initial pressure (time T1). The brake control pressure is a target value of the hydraulic pressure supplied to the brake B1, and corresponds to a current value (instruction value) input to the hydraulic control valve for the brake B1. When the brake control pressure is held at the backlash hydraulic pressure over a predetermined backlash filling time (time T1-T2), the brake control pressure is then lowered from the backlash hydraulic pressure to the initial pressure (time T2). The backlash time and the initial pressure are stored in the memory. While the brake control pressure is held by the backlash hydraulic pressure, the piston of the brake B1 is hydraulically pressed to cancel the invalid stroke of the piston.

  After the brake control pressure is held at the initial pressure for a predetermined time (time T2 to T3), the brake control pressure is gradually increased from the initial pressure with a predetermined time gradient (time change rate). As a result, the hydraulic pressure supplied to the brake B1 rises. As the hydraulic pressure supplied to the brake B1 increases, the transmission torque capacity of the brake B1 increases and the turbine speed starts to decrease. Since the turbine runner 32 rotates integrally with the input shaft 41 of the power split type continuously variable transmission 4, the turbine rotational speed is the same as the rotational speed of the input shaft 41.

  When the brake B1 is almost completely engaged, the turbine rotation is stopped (time T4). When the turbine rotation stops, the brake control pressure is thereafter raised to the maximum pressure, and the engagement control is ended (time T5).

  On the other hand, in the gear ratio control, for example, the gear ratio control pressure is increased at a constant time gradient so that the belt gear ratio changes to the target gear ratio α in a predetermined time from the instruction to switch from the neutral range to the reverse range. . The gear ratio control pressure is a target value of the hydraulic pressure supplied to the primary pulley 53 of the continuously variable transmission mechanism 43, and corresponds to the current value input to the hydraulic control valve for the primary pulley 53. As the transmission ratio control pressure increases, the hydraulic pressure supplied to the primary pulley 53 increases, and the movable sheave 62 of the primary pulley 53 moves toward the fixed sheave 61, so that the belt transmission ratio becomes toward the target transmission ratio α. Decrease gradually. The target gear ratio α is set, for example, such that the unit gear ratio in the reverse range matches the maximum value of the unit gear ratio in the drive range, that is, the maximum value of the belt gear ratio.

<Learning in engagement control>

  In parallel with the engagement control, a learning process is executed by the transmission ECU 12.

  In the learning process, an elapsed time after the state of the reverse switch 15 is switched from off to on is measured. Then, when the transmission torque capacity of the clutch increases and the turbine rotation speed decreases by a predetermined amount, the elapsed time measured up to that point is acquired. The elapsed time fluctuates due to individual variations of the piston stroke time with individual variations, and hydraulic control valves (solenoid valves) that adjust the hydraulic pressure supplied to the brake B1.

  Then, it is determined whether the elapsed time is within a predetermined learning time range. The learning time range is preset to the target time, for example, with the time (time T1-T3) from when the reverse switch 15 is switched from off to on to when the gradual increase of the brake control pressure is started (time T1-T3). The upper limit time is a value obtained by adding the dead zone time, and the lower limit time is a value obtained by subtracting the dead zone time from the target time.

  If the elapsed time exceeds the upper limit of the learning time range, for example, the backlash time and / or the initial pressure are corrected to be increased. Also, if the elapsed time falls below the lower limit of the learning time range, for example, the backlash time and / or the initial pressure are corrected to decrease. Then, the post-correction backlash time and / or the initial pressure are updated and stored in the memory. Thereby, the setting mode (setting mode of the instruction value) of the brake control pressure at the initial stage of the engagement control is learned. Thereafter, the learning process is ended.

  If the elapsed time is within the learning time range, correction of backlash time and / or initial pressure is not performed, and learning of the setting mode of the brake control pressure is not performed.

<Gear ratio control start timing determination processing>

  FIG. 6 is a flowchart showing a flow of processing for determining the start timing of the gear ratio control.

  When the state of the reverse switch 15 is switched from OFF to ON (YES in Step S1), the transmission ECU 12 determines the start timing of the gear ratio control.

  When determining the start timing of the transmission ratio control, first, the output of the water temperature sensor 14 is referred to, and the water temperature of the cooling water flowing through the engine 2 is acquired. Next, it is determined whether the acquired water temperature is a low temperature equal to or lower than a predetermined temperature (step S2).

  If the water temperature is a low temperature below the predetermined temperature (YES in step S2), gear ratio control is started simultaneously with the start of engagement control (step S3). That is, the start timing of the gear ratio control is set to the same timing as the start timing of the engagement control.

  If the water temperature is higher than the predetermined temperature (NO in step S2), it is determined whether learning of the setting mode of the brake control pressure has been completed or not (step S4). For example, in the learning process executed in parallel with the predetermined number of engagement control operations going back from the previous engagement control, when learning of the brake control pressure setting mode is not performed, the brake control pressure setting mode If it is determined that the learning is completed and the learning of the setting mode of the brake control pressure is performed even once, it is determined that the learning of the setting mode of the brake control pressure is not completed.

  If learning of the brake control pressure setting mode has been completed (YES in step S4), gear ratio control is started simultaneously with the start of engagement control (step S3).

  On the other hand, when learning of the setting mode of the brake control pressure is not completed (NO in step S4), the engagement control is preferentially started, and the start of the gear ratio control is suppressed. Then, the engagement control proceeds, the transfer torque capacity of the brake B1 increases, the turbine rotational speed starts to decrease, and when it is determined that the turbine rotational speed decreases, as shown by the two-dot chain line in FIG. The transmission ratio control is started (step S5). That is, the start timing of the gear ratio control is set to a timing delayed from the start timing of the engagement control.

<Effect>

  As described above, when the shift lever is shifted to the reverse position, the brake control pressure (instruction value) for engaging control for engaging the brake B1 is set, and the hydraulic pressure corresponding to the brake control pressure is set to the brake B1. To be supplied. When the brake B1 is engaged by the supply of the hydraulic pressure, the carrier 82 of the planetary gear mechanism 45 of the power split type continuously variable transmission 4 is stopped (rotation is prohibited). By stopping the carrier 82, the rotation direction of the ring gear 83 of the planetary gear mechanism 45 is reverse to the rotation direction of the sun gear 81, and a reverse range is configured.

  A learning process is performed in parallel with the engagement control. In the learning process, an elapsed time from when the state of the reverse switch 15 is switched from off to on to when the turbine rotational speed decreases by a predetermined amount is acquired. And in engagement control of brake B1, the setting aspect of brake control pressure is learned based on the acquired elapsed time.

  In the reverse range, the reverse driving force increases, so it is desirable to reduce the speed ratio (belt speed ratio) of the continuously variable transmission mechanism 43. However, when learning of the brake control pressure setting mode is performed, if the belt speed ratio is changed, oil is supplied to the continuously variable transmission mechanism 43, and the flow rate of oil supplied to the brake B1 is not stable. There is a risk that learning will be mislearning.

  Therefore, when learning is completed or not completed, and learning is not completed, execution of gear ratio control for reducing the belt gear ratio is suppressed. As a result, it is possible to suppress false learning in the engagement control of the brake B1. On the other hand, when the learning is completed, it is not necessary to execute the learning, so the transmission ratio control for reducing the belt transmission ratio is performed. By executing the gear ratio control, the belt gear ratio can be reduced and the reverse driving force can be suppressed.

  Further, when the temperature of the cooling water flowing through the engine 2 is a low temperature equal to or lower than a predetermined temperature, the gear ratio control is started simultaneously with the start of the engagement control in response to the shift lever being shifted to the reverse position. The When the coolant temperature is low, the idling speed of the engine 2 is higher than that in the normal condition, so that the reverse driving force due to torque converter creep during idling of the engine 2 is large. Therefore, when the coolant temperature is low, it is preferable to start the gear ratio control simultaneously with the start of the engagement control, thereby suppressing the reverse driving force. And when the idling speed of the engine 2 is high, the oil pressure generated by the oil pump is high, so that the flow rate of the oil supplied to the brake B1 can be kept stable, and the setting mode of the brake control pressure is learned. The learning is unlikely to be mislearning

<Other Configurations of Power Split Type Continuously Variable Transmission>

  FIG. 7 is a skeleton diagram showing another configuration of the power split continuously variable transmission.

  Instead of the power split type continuously variable transmission 4 of the configuration shown in FIG. 2, a power split type transmission 901 shown in FIG. 7 may be employed.

  The power split type continuously variable transmission 901 is provided with a continuously variable transmission mechanism 902 for continuously changing the power by changing the gear ratio, a constant transmission mechanism 903 for changing the power at a constant gear ratio, and a power The output planetary gear mechanism 904 is provided.

  The continuously variable transmission mechanism 902 has a configuration similar to that of a well-known belt-type continuously variable transmission (CVT). The primary shaft 905 is directly coupled to the input shaft 906. The secondary shaft 907 supports the sun gear 908 of the output planetary gear mechanism 904 in a relatively non-rotatable manner. An output shaft 910 is connected to the ring gear 909 of the output planetary gear mechanism 904. The rotation of the output shaft 910 is transmitted to the differential gear 913 via the first output idle gear 911 and the second idle gear 912, and transmitted from the differential gear 913 to the left and right drive wheels.

  The constant speed change mechanism 903 includes a speed increasing planetary gear mechanism 914, a split drive gear 915, a split driven gear 916, and an idle gear 917. The sun gear 918 of the speed increasing planetary gear mechanism 914 is externally fitted on the input shaft 906 so as to be relatively rotatable. The carrier 919 of the speed increasing planetary gear mechanism 914 is supported by the input shaft 906 so as not to be relatively rotatable. The split drive gear 915 is provided so as to be integrally rotatable with the sun gear 918. The split driven gear 916 is provided so as to rotate integrally with the carrier 920 of the planetary gear mechanism 904 for output. The idle gear 917 meshes with the split drive gear 915 and the split driven gear 916.

  FIG. 8 is a diagram illustrating states of the clutch C1 and the brakes B1 and B2 during forward and reverse travel. In FIG. 7, “◯” indicates that the clutch C1 and the brakes B1 and B2 are engaged. “X” indicates that the clutch C1 and the brakes B1 and B2 are in the released state.

  The power split type continuously variable transmission 901 has, as a power transfer mode, a belt mode in which power is transmitted to the output planetary gear mechanism 904 only via the continuously variable transmission mechanism 902, and power is continuously variable mechanism 902 and constant. A split mode transmitted to the output planetary gear mechanism 904 via the transmission mechanism 903.

  In the belt mode, the clutch C1 is engaged, the sun gear 908 and the ring gear 909 of the output planetary gear mechanism 904 are directly connected, the brakes B1 and B2 are released, and the carrier 920 of the output planetary gear mechanism 904 is free. Put into a state. Therefore, when the primary shaft 905 is rotated by the power input to the input shaft 906, the rotation of the primary shaft 905 is transmitted to the secondary shaft 907 via the belt 921, and the sun gear 908 and the ring gear 909 of the output planetary gear mechanism 904 are transmitted. Rotate integrally, and the output shaft 910 rotates integrally with the ring gear 909. Therefore, in the belt mode, the transmission ratio of the power split type continuously variable transmission 901 matches the transmission ratio (belt transmission ratio) of the continuously variable transmission mechanism 902.

  In the split mode, the clutch C1 and the brake B1 are released. Further, by engaging the brake B2, the ring gear 922 of the speed increasing planetary gear mechanism 914 is braked. Therefore, when the primary shaft 905 rotates by the power input to the input shaft 906, the rotation of the primary shaft 905 is transmitted to the secondary shaft 907 via the belt 921, and the sun gear 908 of the output planetary gear mechanism 904 rotates. . On the other hand, since the ring gear 922 of the speed increasing planetary gear mechanism 914 is braked, the rotation of the input shaft 906 causes the carrier 919, the sun gear 918, the split drive gear 915, the idle gear 917, and the split of the speed increasing planetary gear mechanism 914 to rotate. Through the driven gear 916, the speed is increased and transmitted to the carrier 920 of the output planetary gear mechanism 904. Therefore, in the split mode, the larger the belt speed ratio, the smaller the speed ratio (unit speed ratio) of the power split type continuously variable transmission 901, and the speed ratio less than the speed ratio (split speed ratio) of the constant speed change mechanism 903. Can be realized.

  In the reverse range, the clutch C1 and the brake B2 are released and the brake B1 is engaged. The split drive gear 915 is braked by the engagement of the brake B1. Due to the braking of the split drive gear 915, the idle gear 917 cannot be rotated, and the split driven gear 916 and the carrier 920 of the output planetary gear mechanism 904 cannot be rotated. Therefore, when rotation is transmitted from the input shaft 906 to the sun gear 908 of the output planetary gear mechanism 904 via the primary shaft 905 and the secondary shaft 907, the ring gear 909 of the output planetary gear mechanism 904 rotates in the opposite direction to the sun gear 908. Then, the output shaft 910 rotates in the direction opposite to that when the vehicle moves forward.

<Modification>

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, in the above-described embodiment, when the temperature of the cooling water flowing through the engine 2 is a low temperature equal to or lower than a predetermined temperature, the gear shift is performed simultaneously with the start of the engagement control in response to the shift lever being shifted to the reverse position. It is assumed that the ratio control is started. However, this is merely an example, and in a situation where the output torque of the engine 2 becomes higher than the output torque at idle rotation in the normal state, the shift is changed in response to the shift lever being shifted to the reverse position. Ratio control may be initiated. That is, when any one or more of the following conditions (1) to (4) is satisfied, in response to the shift lever being shifted to the reverse position regardless of whether learning is completed or not Alternatively, transmission ratio control may be started to reduce the belt transmission ratio.

(1) The rotational speed of the engine 2 (engine rotational speed) is equal to or greater than a predetermined rotational speed.
(2) The output torque (engine torque) of the engine 2 is equal to or greater than a predetermined torque value.
(3) The water temperature of the cooling water flowing through the engine 2 is equal to or lower than the predetermined temperature (the above embodiment).
(4) The oil temperature of the power split type continuously variable transmission 4 is equal to or less than a predetermined temperature.

  In the above-described embodiment, the mechanical oil pump is used as the oil pump. However, the oil pump is not limited to the mechanical oil pump, and is an electric oil pump driven by the power of an electric motor. Also good.

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

1 vehicle 4 power split type continuously variable transmission 12 transmission ECU (instruction value setting means, learning means, learning completion judging means, transmission ratio control means)
15 Reverse switch (reverse instruction detection means)
41 input shaft 42 output shaft 43 continuously variable transmission mechanism 45 planetary gear mechanism 46 split drive gear 47 split driven gear 51 primary shaft 52 secondary shaft 53 primary pulley 54 secondary pulley 55 belt 81 sun gear 82 carrier 83 ring gear 84 pinion gear B1 brake (engagement element)

Claims (1)

An input shaft to which power is input, an output shaft for outputting power, a primary shaft to which power is transmitted from the input shaft, a primary pulley supported by the primary shaft, and a secondary shaft provided in parallel with the primary shaft A continuously variable transmission mechanism including a secondary pulley supported by the secondary shaft, and a belt wound around the primary pulley and the secondary pulley; a carrier; a sun gear provided integrally rotatably with the secondary shaft; A planetary gear mechanism including a ring gear provided so as to rotate integrally with the output shaft; a split drive gear to which power of the input shaft is transmitted / cut off; and a gear train with the split drive gear; Equipped with a split driven gear that rotates integrally A control device for controlling a power split type continuously variable transmission comprising an engagement element to be engaged / released by hydraulic pressure to prohibit / permit the row axis type gear mechanism, the rotation of the carrier,
Reverse instruction detection means for detecting a reverse instruction;
Instruction value setting means for setting an instruction value for engagement control for engaging the engagement element in response to detection of a reverse instruction by the reverse instruction detection means;
Learning means for learning the setting mode of the indication value by the indication value setting means based on the time from the detection of the reverse indication by the reverse indication detection means to the time when the number of rotations of the input shaft indicates a predetermined change;
Learning completion judging means for judging completion / non-completion of learning by the learning means;
When it is determined that the learning is completed by the learning completion determination means when the reverse instruction is detected by the reverse instruction detection means, the gear ratio of the continuously variable transmission mechanism is responded to the detection of the reverse instruction. A control apparatus, comprising: transmission ratio control for reducing the transmission ratio, and transmission ratio control means for suppressing execution of the transmission ratio control when it is determined by the learning completion determination means that learning has not been completed.

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