JP2017044241A - Control device of power split type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a power split type continuously variable transmission, which can suppress reverse driving force while inhibiting erroneous learning in engagement control of engagement elements.SOLUTION: When a shift lever is shifted to a reverse position, engagement control is started and a hydraulic pressure according to a brake control pressure is supplied to brakes. Learning processing is executed in parallel to the engagement control. In the learning processing, a lapsed time from a time point when the state of a reverse switch is changed from off to on to a time point when a turbine rotation speed lowers by a predetermined amount is acquired, and based on the acquired lapsed time, a setting mode of the brake control pressure is learned. When the learning is not completed, execution of speed change ratio control for decreasing a belt speed change ratio is inhibited. On the other hand, when the learning is completed, the speed change ratio control for decreasing the belt speed change ratio is executed. With the execution of the speed change ratio control, reverse driving force is suppressed.SELECTED DRAWING: Figure 5

Description

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

  As a transmission mounted on a vehicle such as an automobile, a continuously variable transmission mechanism that continuously changes engine power, a gear mechanism that transmits engine power without going through a continuously variable transmission mechanism, and a continuously variable transmission mechanism There has been proposed a planetary gear mechanism for synthesizing the power from the gear and the power from the gear mechanism. In this transmission, the power from the engine can be divided into a continuously variable transmission mechanism and a gear mechanism, and the divided powers can be combined 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). Engine power 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 that transmits / cuts off the power of the input shaft, and a split driven gear that forms a gear train with the split drive gear and rotates integrally with the 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 is transmitted from the differential gear to the left and right drive wheels.

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

  In the belt mode, the sun gear and the ring gear of the planetary gear mechanism are directly connected. Further, the transmission of power from the input shaft to the split drive gear is interrupted, so that the split drive gear is in a free rotation state (free), and the carrier of the planetary gear mechanism is in a free rotation state. Therefore, the sun gear and the ring gear rotate integrally with the power output from the continuously variable transmission mechanism, and the output shaft rotates integrally with the ring gear. 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. In addition, power is transmitted from the input shaft to the split drive gear, and the power is increased from the split drive gear via the split driven gear at a constant speed ratio (split speed ratio) and input to the carrier of the planetary gear mechanism. The Therefore, if the rotational speed input to the input shaft is constant, the carrier rotational speed is kept constant. Therefore, when the belt transmission ratio is increased and the rotation speed of the sun gear is decreased, the rotation speed of the ring gear and the output shaft connected to the ring gear is increased and the unit transmission ratio is decreased. Therefore, in the split mode, the unit speed ratio is less than or equal to the split speed ratio.

  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 element. Therefore, when the sun gear is rotated by the power output from the continuously variable transmission mechanism, the output shaft rotates in the direction opposite to the rotation direction of the sun gear integrally with the ring gear. At this time, due to the configuration of the planetary gear mechanism, the rotational speed of the ring gear is necessarily lower than the rotational speed of the sun gear.

  For this reason, the maximum value of the unit gear ratio during reverse travel (maximum reverse gear ratio) is greater than the maximum value of the unit gear ratio during forward travel (maximum forward gear ratio). 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 shifting to the reverse range, it is also necessary to engage an engagement element (brake) for fixing the carrier. Therefore, the pulley and the engagement element of the continuously variable transmission mechanism are used for changing the belt speed ratio and engaging the engagement element when the engine rotation speed is the idle rotation speed and the discharge flow rate of the oil pump is small. Must be supplied with hydraulic pressure.

  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 until the rotation speed of the input shaft of the power split continuously variable transmission (rotation speed of the turbine runner of the torque converter) starts to decrease. The piston stroke time is measured, and learning such as the hydraulic 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 variations in piston stroke time is suppressed.

  However, when shifted to the reverse range, oil must be supplied to the pulley and the engaging element of the continuously variable transmission mechanism with a small discharge flow rate of the oil pump. There is a possibility that learning for stabilizing the piston stroke time is erroneously learned.

  An object of the present invention is to control a power split type continuously variable transmission capable of suppressing reverse learning (driving force output to an output shaft during reverse travel) while suppressing erroneous learning in engagement control of engagement elements. Is to provide 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. A continuously variable transmission mechanism comprising a primary shaft, a primary pulley supported by the primary shaft, a secondary shaft provided in parallel with 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 to rotate integrally with the secondary shaft, a ring gear provided to rotate integrally with the output shaft, and a split drive gear to which power of the input shaft is transmitted / cut off, And split drive gears and gear trains that rotate together 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; Based on the time from the detection of the reverse instruction by the reverse instruction detection means to the time when the rotational speed of the input shaft shows a predetermined change, the learning means for learning the setting mode of the instruction value by the instruction value setting means, and the 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 where the learning is judged to be incomplete by the learning completion judging means in response to the detection of the reverse instruction, in which the gear ratio control for reducing the gear ratio of the continuously variable transmission mechanism is executed. Includes 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 equipped with a shift lever, the shift lever is operated to the reverse position (R position) to shift (switch to the reverse range). ) Is instructed.

  According to this configuration, when a reverse instruction is given, an instruction value for engagement control for engaging the engagement element is set, and 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 the hydraulic pressure is supplied to the engagement element, the time from the reverse instruction until the rotational speed of the input shaft shows a predetermined change due to the increase in the transmission torque capacity is acquired. And in engagement control of an engagement element, the setting mode of the instruction value for controlling the hydraulic pressure supplied to an engagement element is learned based on the acquired time.

  In the reverse range, the reverse driving force increases, so it is desirable to reduce the gear ratio of the continuously variable transmission mechanism. However, when the instruction value setting mode 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. Therefore, there is a possibility that learning becomes mislearning.

  Therefore, when learning is completed / uncompleted and learning is not completed, execution of gear ratio control for reducing the gear ratio of the continuously variable transmission mechanism is suppressed. Thereby, the mislearning in the engagement control of an 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 gear ratio control, the gear ratio of the continuously variable transmission mechanism can be reduced, and the reverse driving force can be suppressed.

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

(1) The engine speed (engine speed) of a vehicle on which the power split type continuously variable transmission is mounted is equal to or higher than a predetermined 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 continuously variable transmission is equal to or lower than a predetermined temperature.

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

It is a figure which shows the structure of the principal part of the vehicle by which the control apparatus which concerns on one Embodiment of this invention is mounted. It is a skeleton figure which shows the structure of the drive system of a vehicle. It is a figure which shows the state of a clutch and a brake at the time of advance of a vehicle, and reverse drive. It is a collinear diagram which shows the relationship of the rotation speed (rotation speed) of the sun gear of a planetary gear mechanism, a carrier, and a ring gear. It is a figure which shows an example of the time change of the state of a reverse switch, a belt gear ratio, a turbine speed, and brake control pressure when a 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. It is a skeleton figure which shows the other structure of a power division type continuously variable transmission. It is a figure which shows the state of the clutch and brake in each motive power transmission mode in the motive power division type continuously variable transmission shown by FIG.

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

<Vehicle configuration>

  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 that uses the 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 into the combustion chamber of the engine 2 and an ignition plug for generating 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 be capable of bidirectional communication using 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 in the engine 2 for starting, stopping, and adjusting the output of the engine 2 based on numerical values obtained from signals inputted from various sensors and various information inputted from other ECUs. 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 turned on when the shift lever (select lever) is located at the reverse position, and is turned off when the shift lever is located 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 correspond to the shift range parking range (parking range), reverse range (reverse range), neutral range (neutral range), and drive range (forward range), respectively. The shift lever can be shifted between a parking position, a reverse position, a neutral position, and a drive position, and a shift range can be instructed by the shift operation.

  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 speed 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 controlling a valve included in the hydraulic circuit 17, and switches between 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 based on a current value, for example, a linear solenoid valve is used.

<Configuration of drive system>

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

  The engine 2 includes 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. An E / G output shaft 21 is connected to the pump impeller 31, and the pump impeller 31 is provided so as to be integrally rotatable about the same rotation axis as the E / G output shaft 21. The turbine runner 32 is provided to be rotatable about the same rotation axis as the pump impeller 31. The lockup clutch 33 is provided to directly connect / separate the pump impeller 31 and the turbine runner 32. When the lockup clutch 33 is engaged, the pump impeller 31 and the turbine runner 32 are directly connected, 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 rotates. When the pump impeller 31 rotates, an oil flow 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.

  In a state where the lockup clutch 33 is 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 are rotated together.

  The power split type continuously variable transmission 4 transmits the power input from the torque converter 3 to the 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 is provided so as to be integrally rotatable about 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). Specifically, the continuously variable transmission mechanism 43 includes a primary shaft 51, a secondary shaft 52 provided in parallel with the primary shaft 51, a primary pulley 53 supported by the primary shaft 51 so as not to be relatively rotatable, and a secondary shaft 52. And a secondary pulley 54 supported so as not to rotate relative thereto, and a primary pulley 53 and a belt 55 wound around the secondary pulley 54.

  The primary pulley 53 is disposed so as to face the fixed sheave 61 fixed to the primary shaft 51 with the belt 55 sandwiched between the fixed sheave 61 and is supported by the primary shaft 51 so as to be movable in the axial direction but not to be relatively rotatable. 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.

  The secondary pulley 54 is arranged so as to be opposed to the fixed sheave 65 fixed to the secondary shaft 52 with the belt 55 sandwiched between the fixed sheave 65 and supported on the secondary shaft 52 so as to be movable in the axial direction but not to be relatively rotatable. 66. A cylinder (not shown) 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 (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, and the groove widths of the primary pulley 53 and the secondary pulley 54 are changed, whereby the continuously variable transmission mechanism. The belt speed ratio, which is the speed ratio at 43, is continuously changed continuously.

  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 to the fixed sheave 61 side, and the interval (groove width) between the fixed sheave 61 and the movable sheave 62 is reduced. Accordingly, the winding diameter of the belt 55 around the primary pulley 53 is increased, and the interval (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 decreased. Thereby, the thrust of the secondary pulley 54 with respect to the belt 55 becomes larger than the thrust of the primary pulley 53 with respect to the belt 55, the interval between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 is reduced, and the fixed sheave 61 and the movable sheave The distance from 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, and cannot rotate relative to the primary shaft 51. 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 arranged on the circumference and mesh with the sun gear 81. The ring gear 83 has an annular shape that collectively surrounds the plurality of pinion gears 84, and meshes with the pinion gears 84 from the outside in the rotational radial direction of the secondary shaft 52. An output shaft 42 is connected to the ring gear 83, and the ring gear 83 is provided so as to be integrally rotatable about 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 so as to be integrally rotatable) 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 so as to be integrally rotatable) and a released state (off) in which the direct coupling is released.

  The brake B <b> 1 is switched between an engaged state (on) in which the carrier 82 of the planetary gear mechanism 45 is braked and a released state (off) in which the rotation of the carrier 82 is allowed.

<Power transmission mode>

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

  FIG. 4 is a collinear diagram 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 power transmission modes 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 speed ratio, which is the overall speed ratio of the power split type continuously variable transmission 4, matches the belt speed 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.

  A part of the power input to the input shaft 41 is reversely rotated and decelerated by the reverse gear mechanism 44 and transmitted to the primary shaft 51 of the continuously variable transmission mechanism 43, and from the primary shaft 51 to the primary pulley 53, the belt 55 and the secondary pulley. 54 is transmitted to the secondary shaft 52 through 54, and is 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 and transmitted from the split drive gear 46 to the carrier 82 of the planetary gear mechanism 45 via the split driven gear 47.

  Since 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), 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 held 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, so that the rotational speed of the ring gear 83 (output shaft 42) of the planetary gear mechanism 45 as shown 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 moving the vehicle 1 backward, 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 and transmitted to the primary shaft 51 of the continuously variable transmission mechanism 43, and is transmitted from the primary shaft 51 via 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 rotation direction of the ring gear 83 is opposite to the rotation direction of the ring gear 83 during 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 diagram illustrating an example of the time change of the state of the reverse switch, the belt speed ratio, the turbine speed, and 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 change of the state of the reverse switch 15 from OFF to ON, the transmission ECU 12 detects an instruction to switch (shift) from the neutral range to the reverse range by a 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 hydraulic pressure that is 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 (indicated 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 backlashing time and the initial pressure are stored in the memory. While the brake control pressure is held at the backlash hydraulic pressure, the piston of the brake B1 is pushed by the hydraulic pressure, and the invalid stroke of the piston is eliminated.

  After the brake control pressure is maintained at the initial pressure over a predetermined time (time T2-T3), the brake control pressure is gradually increased from the initial pressure at a predetermined time gradient (time change rate). As a result, the hydraulic pressure supplied to the brake B1 increases. 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 is stopped, the brake control pressure is then increased to the maximum pressure, and the engagement control is terminated (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 transmission 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 speed ratio α is set, for example, so that the unit speed ratio in the reverse range matches the maximum value of the unit speed ratio in the drive range, that is, the maximum value of the belt speed 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. This elapsed time varies depending on individual variations such as a piston stroke time with individual variations and a hydraulic control valve (solenoid valve) that adjusts 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 set in advance as a target time, for example, with a time (time T1-T3) from the time when the reverse switch 15 is switched from OFF to ON until the time when the brake control pressure starts to increase gradually is set as the target time. The value obtained by adding the dead zone time is set as the upper limit time, and the value obtained by subtracting the dead zone time from the target time is set as the lower limit time.

  When the elapsed time exceeds the upper limit of the learning time range, for example, the backlash time and / or the initial pressure is corrected to be increased. Further, when the elapsed time is below the lower limit of the learning time range, for example, the backlashing time and / or the initial pressure is corrected to decrease. Then, the corrected backlash time and / or initial pressure is updated and stored in the memory. Thereby, the brake control pressure setting mode (instruction value setting mode) in the initial stage of the engagement control is learned. Thereafter, the learning process is terminated.

  When the elapsed time is within the learning time range, the backlash time and / or the initial pressure is not corrected, and the brake control pressure setting mode is not learned.

<Transmission ratio control start timing determination process>

  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 gear ratio control, first, the output of the water temperature sensor 14 is referred to, and the temperature of the cooling water flowing through the engine 2 is acquired. Next, it is determined whether or not the acquired water temperature is a low temperature below a predetermined temperature (step S2).

  If the water temperature is a low temperature equal to or lower than 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.

  When the water temperature is higher than the predetermined temperature (NO in step S2), it is determined whether learning of the brake control pressure setting mode is completed or not completed (step S4). For example, in the learning process executed in parallel with a predetermined number of engagement controls retroactive from the previous engagement control, when learning of the brake control pressure setting mode is not performed, the brake control pressure setting mode is changed. When it is determined that learning has been completed and learning of the brake control pressure setting mode has been performed even once, it is determined that learning of the brake control pressure setting mode has not been 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 brake control pressure setting mode is not completed (NO in step S4), the engagement control is preferentially started, and the start of the gear ratio control is suppressed. Then, when the engagement control advances, the transmission 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 a two-dot chain line in FIG. Then, gear 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 supplying 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 reversed from the rotation direction of the sun gear 81, and a reverse range is configured.

  In parallel with the engagement control, a learning process is executed. In the learning process, an elapsed time from the time when the state of the reverse switch 15 is switched from OFF to ON until the time when the turbine 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. Learning may be mis-learning.

  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. Thereby, mislearning in the engagement control of the brake B1 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 belt gear ratio is executed. 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 mis-learning.

<Other configuration 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 having 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 includes a continuously variable transmission mechanism 902 that changes the power continuously by changing the speed ratio, a constant speed change mechanism 903 that changes the power at a constant speed ratio, and power output. The planetary gear mechanism 904 for output is provided.

  The continuously variable transmission mechanism 902 has the same configuration as a known belt-type continuously variable transmission (CVT). The primary shaft 905 is directly connected 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 is 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 to 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 able to rotate integrally 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 includes, as a power transmission mode, a belt mode in which power is transmitted to the output planetary gear mechanism 904 via only the continuously variable transmission mechanism 902, and power is continuously variable with the continuously variable transmission mechanism 902. 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 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 gear ratio of the power split continuously variable transmission 901 matches the gear ratio (belt gear 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 if the output torque of the engine 2 is higher than the output torque during idle rotation in a normal state, the gear shift is performed 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 The transmission ratio control for reducing the belt transmission ratio may be started.

(1) The rotational speed of the engine 2 (engine rotational speed) is equal to or higher 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 temperature of the cooling water flowing through the engine 2 is equal to or lower than a predetermined temperature (the above-described embodiment).
(4) The oil temperature of the power split type continuously variable transmission 4 is equal to or lower 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.

DESCRIPTION OF SYMBOLS 1 Vehicle 4 Power split type continuously variable transmission 12 Transmission ECU (instruction value setting means, learning means, learning completion judgment 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 comprising a secondary pulley supported by the secondary shaft, a belt wound around the primary pulley and the secondary pulley, a carrier, a sun gear provided so as to be integrally rotatable with the secondary shaft, and 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;
In response to detection of a reverse instruction by the reverse instruction detection means, instruction value setting means for setting an instruction value for engagement control for engaging the engagement element;
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 until the rotational speed of the input shaft shows a predetermined change;
Learning completion judging means for judging completion / non-completion of learning by the learning means;
When the reverse instruction is detected by the reverse instruction detecting means, if the learning completion determining means determines that learning is completed, the gear ratio of the continuously variable transmission mechanism is determined in response to the detection of the reverse instruction. And a transmission ratio control unit that suppresses the execution of the transmission ratio control when the learning completion determination unit determines that the learning is incomplete.

Images