JP2016142302A - 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 capable of improving controllability in kick-down control in accompany with switching from a split mode to a belt mode.SOLUTION: When execution of kick-down control in accompany with switching from a split mode to a belt mode, is determined, change of a belt transmission ratio γis started in response to the determination. Further the total of a flow rate of an oil necessary for changing the belt transmission ratio γand a flow rate of an oil necessary for engagement of a clutch for switching from the split mode to the belt mode, is calculated as a necessary flow rate (Step S1). Furthermore, a flow rate of an oil discharged from an oil pump 5 is calculated as a supply flow rate (Step S2). The necessary flow rate and the supply flow rate are compared, and the supply of a hydraulic pressure to a low clutch is started (Step S4), when the supply flow rate is more than the necessary flow rate (YES in step S3).SELECTED DRAWING: Figure 7

Description

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

  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 the proposal includes a continuously variable transmission mechanism that continuously changes power by changing a transmission ratio, a constant transmission mechanism that changes power at a constant transmission ratio, and a continuously variable transmission mechanism. And a planetary gear mechanism for synthesizing the power passing through the power and the power passing through the constant speed change mechanism. The continuously variable transmission mechanism has the same configuration as a known belt-type continuously variable transmission (CVT). A secondary shaft of a continuously variable transmission mechanism is connected to the sun gear 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.

  This power split type continuously variable transmission has, as power transmission modes, a belt mode in which power is transmitted to the planetary gear mechanism only through the continuously variable transmission mechanism, and power through the continuously variable transmission mechanism and the constant transmission mechanism. And a split mode transmitted to the planetary gear mechanism.

  In the belt mode, the sun gear and the ring gear of the planetary gear mechanism are directly connected, and the carrier of the planetary gear mechanism is brought into a free 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 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, and the power passing through the constant speed change mechanism is input to the carrier. Since the speed ratio (split speed ratio) of the constant speed change mechanism is constant and unchanged, if the rotational speed input to the power split continuously variable transmission is constant, the rotational speed of the carrier 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 output shaft connected to the ring gear and the ring gear is increased, and the transmission ratio of the power split continuously variable transmission is decreased. Therefore, in the split mode, the gear ratio of the power split continuously variable transmission is equal to or less than the split gear ratio.

  When the accelerator pedal is depressed quickly and greatly while driving in the split mode, the power transmission mode is changed to split mode by changing the belt gear ratio by hydraulic pressure and switching the two engagement elements by hydraulic pressure by kickdown control. May be switched to the belt mode.

  When the engine speed is low, the flow rate of oil discharged by the oil pump driven by the engine power is small. For this reason, when kickdown control involving switching from the split mode to the belt mode is performed in a state where the engine speed is low, the flow rate of oil supplied to the continuously variable transmission mechanism and the engagement element is insufficient, and the controllability May get worse.

  An object of the present invention is to provide a control device for a power split type continuously variable transmission capable of improving controllability in kickdown control accompanied with switching from a split mode to a belt mode.

  In order to achieve the above object, a control device according to the present invention includes a drive source, an oil pump driven by the drive source, an input shaft to which power from the drive source is input, and power input to the input shaft. A belt-type continuously variable transmission mechanism that changes continuously by changing the belt transmission ratio, a constant transmission mechanism that changes power input to the input shaft at a constant split transmission ratio, an output gear mechanism that outputs power to the output shaft, And an engagement element engaged by the hydraulic pressure generated by the oil pump, and by the engagement of the engagement element, the power input to the input shaft passes through the continuously variable transmission mechanism and the constant transmission mechanism to the output gear mechanism. Used in vehicles equipped with a power split type continuously variable transmission that switches from split mode transmitted to belt mode in which power input to the input shaft is transmitted to the output gear mechanism via the continuously variable transmission mechanism, A control device for controlling a force-dividing continuously variable transmission, a determination means for determining execution of kickdown control accompanied with change of a belt speed ratio and switching from a split mode to a belt mode, and execution of kickdown control In response to the determination, a shift control unit that starts changing the belt transmission ratio by controlling the hydraulic pressure supplied to the continuously variable transmission mechanism, a discharge flow rate calculation unit that calculates a flow rate of oil discharged from the oil pump, and a belt Calculated by the required flow rate calculation means that calculates the sum of the oil flow rate required for changing the gear ratio and the oil flow rate required for engagement of the engagement elements, and by the discharge flow rate calculation means after determining the execution of kickdown control Engagement control means for comparing the flow rate to be calculated with the flow rate calculated by the required flow rate calculation means and starting the supply of hydraulic pressure to the engagement element based on the comparison result

  According to this configuration, when execution of kickdown control involving switching from the split mode to the belt mode is determined, in response to the determination, the belt speed ratio by the control of the hydraulic pressure supplied to the continuously variable transmission mechanism is determined. Change begins. On the other hand, the sum of the oil flow rate required for changing the belt transmission ratio and the oil flow rate required for engaging the engagement element for switching from the split mode to the belt mode is calculated as the required flow rate. Further, the flow rate of oil discharged from the oil pump is calculated as the supply flow rate. Then, the required flow rate and the supply flow rate are compared, and supply of hydraulic pressure to the engagement element is started based on the comparison result. For example, when the supply flow rate is higher than the required flow rate, supply of hydraulic pressure to the engagement element is started.

  As a result, a shortage in the flow rate of the oil supplied to the continuously variable transmission mechanism and the engagement element can be suppressed, and the controllability of kickdown control that involves switching from the split mode to the belt mode along with the change of the belt transmission ratio can be suppressed. Improvements can be made.

  According to the present invention, it is possible to suppress a shortage in the flow rate of oil supplied to the continuously variable transmission mechanism and the engagement element in kickdown control that involves switching from the split mode to the belt mode along with the change of the belt speed ratio. The controllability can be improved. As a result, it is possible to suppress variation in response of the engaging elements, and to suppress occurrence of shift shock.

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 the low clutch, reverse brake, and high brake at the time of advance of a vehicle, and reverse drive. It is a figure which shows the relationship between the gear ratio of a continuously variable transmission mechanism, and the gear ratio of a power division type continuously variable transmission. It is an alignment chart which shows the relationship of the rotation speed of the carrier of an output gear mechanism, a sun gear, and a ring gear. It is a timing chart for demonstrating kickdown control. It is a flowchart which shows the flow of a fill timing determination process.

  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) including a CPU, a ROM, a RAM, and the like. 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 accelerator sensor 13 and an engine speed sensor 14 are connected to the engine ECU 11.

  The accelerator sensor 13 inputs a signal corresponding to an operation amount of an accelerator pedal (not shown) to the engine ECU 11. Based on the signal input from the accelerator sensor 13, the engine ECU 11 sets the ratio of the operation amount to the maximum operation amount of the accelerator pedal, that is, 0% when the accelerator pedal is not depressed, and the accelerator pedal is depressed to the maximum. The accelerator opening, which is a percentage with the time as 100%, is calculated.

  The engine speed sensor 14 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 14 into the speed of the engine 2 (engine speed).

  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 shift position sensor 15, a primary rotation speed sensor 16, a secondary rotation speed sensor 17, an output rotation speed sensor 18, and the like are connected to the transmission ECU 12.

  The shift position sensor 15 inputs a signal corresponding to the position of the shift lever (select lever) to the transmission ECU 12. As positions of the shift lever, for example, a P position, an R position, an N position, and a D position are provided. The P position, the R position, the N position, and the D position correspond to the P range (parking range), R range (reverse range), N range (neutral range), and D range (forward range), respectively. The shift lever can be shifted between the P position, the R position, the N position, and the D position, and the shift range can be instructed by the shift operation.

  The primary rotational speed sensor 16 inputs, for example, a pulse signal synchronized with the rotation of the primary pulley 53 (see FIG. 2) of the power split type continuously variable transmission 4 to the transmission ECU 12. The transmission ECU 12 converts the frequency of the pulse signal input from the primary rotational speed sensor 16 into a primary rotational speed that is the rotational speed of the primary pulley 53 (primary shaft 51).

  The secondary rotational speed sensor 17 inputs, for example, a pulse signal synchronized with the rotation of the secondary pulley 54 (see FIG. 2) of the power split type continuously variable transmission 4 to the transmission ECU 12. The transmission ECU 12 converts the frequency of the pulse signal input from the secondary rotational speed sensor 17 into a secondary rotational speed that is the rotational speed of the secondary pulley 54 (secondary shaft 52).

  The output rotation speed sensor 18 inputs, for example, a pulse signal synchronized with the rotation of the output gear 85 (see FIG. 2) to the transmission ECU 12. The transmission ECU 12 converts the frequency of the pulse signal input from the output rotation speed sensor 18 into an output rotation speed that is the rotation speed of the output shaft 42 (see FIG. 2).

The transmission ECU 12 is based on numerical values obtained from signals input from various sensors, various information input from other ECUs, and the like (hereinafter referred to as “belt transmission ratio”) of the continuously variable transmission mechanism 43. for the control of gamma _b, it controls the valve (not shown) included in the hydraulic circuit 19 for supplying hydraulic pressure to each part of the CVT 43. Further, the transmission ECU 12 controls the hydraulic pressure supplied to the low clutch C1, the reverse brake B1 and the high brake B2 (see FIG. 2) by controlling a valve included in the hydraulic circuit 19, and switches between the forward mode and the reverse mode. Switching between belt mode and split mode.

  The valves of the hydraulic circuit 19 include a hydraulic control valve that adjusts the hydraulic pressure supplied to the primary pulley 53, the secondary pulley 54, the low clutch C1, the reverse brake B1, and the high brake B2, 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.

  An oil pump 5 is provided between the torque converter 3 and the power split type continuously variable transmission 4. The pump shaft of the oil pump 5 is provided so as to be rotatable integrally with the pump impeller 31. Accordingly, when the pump impeller 31 is rotated by the power of the engine 2, the pump shaft of the oil pump 5 is rotated and oil is discharged from the oil pump 5.

  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 constant transmission mechanism 44, and an output gear mechanism 45.

  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.

  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 coupled to the input shaft 41, a secondary shaft 52 provided in parallel with the primary shaft 51, and a primary shaft supported by the primary shaft 51 so as not to be relatively rotatable. The pulley 53, the secondary pulley 54 supported by the secondary shaft 52 so that relative rotation is impossible, and the belt 55 wound around the primary pulley 53 and the secondary pulley 54 are provided.

  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 63 fixed to the primary shaft 51 is provided on the opposite side of the movable sheave 62 from the fixed sheave 61, and an oil chamber 64 is formed between the movable sheave 62 and the cylinder 63.

  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 67 fixed to the secondary shaft 52 is provided on the opposite side of the movable sheave 66 from the fixed sheave 61, and an oil chamber 68 is formed between the movable sheave 66 and the cylinder 67.

In the continuously variable transmission mechanism 43, the hydraulic pressure supplied to the oil chamber 64 of the primary pulley 53 and the oil chamber 68 of the secondary pulley 54 is controlled, and the groove widths of the primary pulley 53 and the secondary pulley 54 are changed. The belt speed ratio γ _b is continuously changed in a stepless manner.

More specifically, when the belt speed ratio gamma _b is lowered, the hydraulic pressure is raised to be supplied to the oil chamber 64 of the primary pulley 53. 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 decreases, and the belt speed ratio γ _b decreases.

When the belt speed ratio gamma _b is raised, the hydraulic pressure is reduced is supplied to an oil chamber 64 of the primary pulley 53. 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 speed ratio γ _b 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 the oil chamber 64 of the primary pulley 53 and the oil chamber 68 of 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 constant speed change mechanism 44 includes a planetary gear mechanism 71, a split drive gear 72, a split driven gear 73, and an idle gear 74.

  The planetary gear mechanism 71 includes a sun gear 75, a carrier 76 and a ring gear 77. The sun gear 75 is fitted on the input shaft 41 so as to be relatively rotatable. The carrier 76 is supported by the input shaft 41 so as not to be relatively rotatable. The carrier 76 supports a plurality of pinion gears 78 in a rotatable manner. The plurality of pinion gears 78 are arranged on the circumference and mesh with the sun gear 75. The ring gear 77 has an annular shape surrounding the carrier 76 and meshes with each pinion gear 78 from the outside in the rotational radial direction of the input shaft 41.

  The split drive gear 72 is provided so as to be able to rotate integrally with the sun gear 75.

  The split driven gear 73 is provided on the outer periphery of the carrier 82 of the output gear mechanism 45 described below so as to be able to rotate integrally with the carrier 82. That is, the constant speed change mechanism 44 is connected to the carrier 82 of the output gear mechanism 45.

  The idle gear 74 meshes with the split drive gear 72 and the split driven gear 73.

  The output gear mechanism 45 has a configuration of a planetary gear mechanism. That is, the output gear mechanism 45 includes a sun gear 81, a carrier 82, and a ring gear 83. The sun gear 81 is externally fitted to the secondary shaft 52 so as not to be relatively rotatable. The secondary shaft 52 of the continuously variable transmission mechanism 43 is inserted in the center of the carrier 82 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 surrounding the periphery of the carrier 82, and meshes with each pinion gear 84 from the outer side in the rotational radial direction of the secondary shaft 52. One end of the 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. An output gear 85 is supported at the other end of the output shaft 42 so as not to be relatively rotatable.

  The rotation of the output gear 85 is transmitted to the differential gear 6 via the first idle gear 86, the idle shaft 87 and the second idle gear 88. The first idle gear 86 is supported by the idle shaft 87 so as not to be relatively rotatable, and meshes with the output gear 85. The idle shaft 87 is provided in parallel with the output shaft 42. The second idle gear 88 is supported by the idle shaft 87 so as not to be relatively rotatable, and meshes with a ring gear 91 provided in the differential gear 6.

  The power split type continuously variable transmission 4 includes a low clutch C1, a reverse brake B1, and a high brake B2.

  The low clutch C1 is switched between an engaged state (on) in which the output shaft 42 and the secondary shaft 52 are directly connected, and a released state (off) in which the direct connection is released.

  The reverse brake B1 is switched between an engaged state (on) for braking the split drive gear 72 (sun gear 75) and a released state (off) for allowing the split drive gear 72 to rotate.

  The high brake B <b> 2 is switched between an engaged state (on) in which the ring gear 77 is braked and a released state (off) in which the rotation of the ring gear 77 is allowed.

<Power transmission mode>

FIG. 3 is a diagram illustrating states of the low clutch C1, the reverse brake B1, and the high brake B2 when the vehicle 1 moves forward and backward. Figure 4 is a diagram showing a relationship between the gear ratio of the belt speed ratio gamma _b power split type continuously variable transmission 4 (hereinafter referred to as "unit speed ratio".) And gamma _u.

  In FIG. 3, “◯” indicates that the low clutch C1, the reverse brake B1, and the high brake B2 are engaged. In the P range and the N range, the low clutch C1, the reverse brake B1, and the high brake B2 are released.

  The power split type continuously variable transmission 4 has a belt mode and a split mode as power transmission modes in the D range.

  In the belt mode, the high brake B2 and the reverse brake B1 are released, and the low clutch C1 is engaged. As a result, the split drive gear 72, the split driven gear 73 and the idle gear 74 of the constant speed change mechanism 44, and the carrier 82 of the output gear mechanism 45 become free (free rotation state), and the output shaft 42 and the secondary shaft 52 are directly connected. .

The power input to the input shaft 41 is 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 low clutch C <b> 1 is engaged, the output shaft 42 rotates integrally with the secondary shaft 52. Therefore, in the belt mode, as shown in FIG. 4, the unit speed ratio γ _u coincides with the belt speed ratio γ _b .

  The rotation of the output shaft 42 is transmitted to the ring gear 91 of the differential gear 6 through the output gear 85, the first idle gear 86, the idle shaft 87 and the second idle gear 88. As a result, the drive shafts 92 and 93 of the vehicle 1 rotate in the forward direction.

  FIG. 5 is a collinear diagram showing the relationship among the rotation speeds of the carrier 82, sun gear 81, and ring gear 83 of the output gear mechanism 45.

  In the split mode, as shown in FIG. 3, the high brake B2 is engaged, and the reverse brake B1 and the low clutch C1 are released. As the high brake B2 is engaged, the ring gear 77 of the constant speed change mechanism 44 is braked. Further, the direct coupling between the output shaft 42 and the secondary shaft 52 is released by releasing the low clutch C1.

  The power input to the input shaft 41 is 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. As the secondary shaft 52 rotates, the sun gear 81 of the output gear mechanism 45 rotates.

  Since the ring gear 77 of the constant speed change mechanism 44 is braked, the power input to the input shaft 41 revolves the carrier 76 of the constant speed change mechanism 44 and rotates the pinion gear 78 held by the carrier 76. Let As the pinion gear 78 rotates, power is input from the pinion gear 78 to the sun gear 75. Thereby, the pinion gear 78 and the split drive gear 72 rotate. The rotation of the split drive gear 72 is transmitted to the split driven gear 73 via the idle gear 74 and rotates the split driven gear 73 and the carrier 82 of the output gear mechanism 45.

Since the gear ratio (hereinafter referred to as “split gear ratio”) γ _{g of the} constant speed change mechanism 44 is constant and unchanged (fixed), if the power input to the input shaft 41 is constant in the split mode, the output gear The rotation of the carrier 82 of the mechanism 45 is held at a constant speed. Therefore, when the belt speed ratio γ _b is increased, the rotational speed of the sun gear 81 of the output gear mechanism 45 is decreased. Therefore, as shown by a two-dot chain line in FIG. ) Increases the rotation speed. As a result, in the split mode, as shown in FIG. 4, the larger the belt speed ratio γ _b , the smaller the unit speed ratio γ _u .

  The rotation of the output shaft 42 is transmitted to the ring gear 91 of the differential gear 6 through the output gear 85, the first idle gear 86, the idle shaft 87 and the second idle gear 88. As a result, the drive shafts 92 and 93 of the vehicle 1 rotate in the forward direction.

  In the R range, as shown in FIG. 3, the high brake B2 and the low clutch C1 are released. Then, the reverse brake B1 is engaged. Thereby, the split drive gear 72 (sun gear 75) is braked. Due to braking of the split drive gear 72, the idle gear 74 of the constant speed change mechanism 44 becomes non-rotatable, and the split driven gear 73 and the carrier 82 become non-rotatable.

  The power input to the input shaft 41 is 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. As the secondary shaft 52 rotates, the sun gear 81 of the output gear mechanism 45 rotates. Since the carrier 82 cannot rotate, as shown by a one-dot chain line in FIG. 5, when the sun gear 81 rotates, the ring gear 83 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 in the D range (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 ring gear 91 of the differential gear 6 through the output gear 85, the first idle gear 86, the idle shaft 87 and the second idle gear 88. As a result, the drive shafts 92 and 93 of the vehicle 1 rotate in the reverse direction.

<Kickdown control>

  FIG. 6 is a timing chart for explaining kick-down control.

In the memory of the transmission ECU 12, a shift line that defines a unit speed ratio γ _u according to the vehicle speed and the accelerator opening is mapped and stored. When the accelerator pedal is depressed, the transmission ECU 12 acquires the accelerator opening from the engine ECU 11, and sets the unit speed ratio γ _u corresponding to the accelerator opening and the vehicle speed as the target unit speed ratio according to the shift line map. The vehicle speed may be calculated from the output rotation speed, or may be calculated from the frequency of a pulse signal provided with a vehicle speed sensor and input from the vehicle speed sensor.

Thereafter, the transmission ECU 12 requires kickdown control (hereinafter simply referred to as “kickdown control”) that involves changing the belt speed ratio γ _b and switching from the split mode to the belt mode based on the target unit speed ratio. No is determined (K / D determination). Specifically, when the target unit speed ratio is larger than the split speed ratio γ _g , it is determined that kick down control is necessary, and when the target unit speed ratio is less than or equal to the split speed ratio γ _g , the kick down control is determined. Is determined to be unnecessary. When it is determined that the kick down control is necessary, the kick down control is started (time T1).

  Switching from the split mode to the belt mode is achieved by changing (grabbing) the low clutch C1 and the high brake B2. That is, switching from the split mode to the belt mode is achieved by releasing the high brake B2 engaged in the split mode and engaging the low clutch C1 released in the split mode.

  Therefore, in kick-down control, first, the release control for releasing the high brake B2 is started by the transmission ECU 12 (time T1). In the release control, the release command pressure of the high brake B2 is decreased with time. The release instruction pressure is a target value of the hydraulic pressure supplied to the high brake B2, and corresponds to a current value input to the hydraulic control valve for the high brake B2.

Further, the transmission ECU 12, the shift control for changing the belt speed ratio gamma _b is started (time T1). In the speed change control, the hydraulic pressure supplied to the primary pulley 53 and the secondary pulley 54 is controlled, and after the belt speed ratio γ _b is lowered to the vicinity of the split speed ratio γ _g , the belt speed ratio γ _b is reduced to the target unit speed ratio. Raised.

  Then, after the kick-down control is started, when the execution of the first fill is determined in the fill timing determination process shown in FIG. 7, the transmission ECU 12 next performs an engagement control for engaging the low clutch C1. Start (time T2).

  In the engagement control, first fill control is performed in which the engagement command pressure is maintained at a constant pressure higher than the initial pressure over a certain time (time T2-T3) after the start of the engagement control. The engagement command pressure is a target value of the hydraulic pressure supplied to the low clutch C1, and corresponds to a current value input to the hydraulic control valve for the low clutch C1. By the first fill control, the low clutch C1 can be filled with oil, and the responsiveness of the low clutch C1 can be improved.

  Following the first fill control, after the engagement command pressure is maintained at the initial pressure for a predetermined time (time T3-T4), the sweep is then performed to increase the engagement command pressure at a constant time gradient (time change rate). Control is started (time T4). By this sweep control, the hydraulic pressure supplied to the low clutch C1 increases.

  When the low clutch C1 is almost completely engaged during the sweep control and the engagement command pressure increases to the maximum pressure, the engagement of the low clutch C1 is completed and the engagement control is terminated (time T5). . Further, after the engagement control is finished, the release command pressure is lowered to 0, and the release control is finished (time T6).

  FIG. 7 is a flowchart showing the flow of the fill timing determination process.

  During the execution of the kick down control, the transmission ECU 12 repeatedly executes the fill timing determination process.

In the fill timing determination process, the flow rate of oil necessary for changing the belt speed ratio γ _b is calculated based on the current unit speed ratio γ _u and the target unit speed ratio. Further, the flow rate of oil necessary for engaging the low clutch C1 is calculated based on the engagement command pressure. Then, the total of these flow rates is calculated as the required flow rate (step S1).

  Further, the flow rate of oil discharged from the oil pump 5 is calculated as the supply flow rate (step S2). Since the oil pump 5 is driven by the power of the engine 2, the capacity (supply flow rate) of the oil pump 5 depends on the current engine speed. Therefore, the current engine speed is acquired from the engine ECU 11, and the supply flow rate of the oil pump 5 at the engine speed is calculated.

  Thereafter, the required flow rate and the supply flow rate are compared. Then, it is determined whether or not the supply flow rate exceeds the required flow rate (step S3).

  When the supply flow rate exceeds the necessary flow rate (YES in step S3), the execution of the fast fill control is determined (step S4), and the fill timing determination process is ended. Thereby, the supply of the hydraulic pressure to the low clutch C1 can be started in a state where the supply flow rate exceeds the necessary flow rate.

On the other hand, when the supply flow rate is equal to or less than the required flow rate (NO in step S3), the time required from the present time until the unit speed ratio γ _u matches the target unit speed ratio (remaining speed change time) is calculated. It is determined whether or not it is longer than the time (clutch response time) required from the start of engagement of the low clutch C1 to the completion of engagement (step S5).

As shown in FIG. 6, the unit speed ratio γ _u is increased by changing the belt speed ratio γ _b , and the turbine rotational speed is increased as the unit speed ratio γ _u is increased. If the target unit gear ratio is larger than the split gear ratio gamma _g, the target unit gear ratio, a final target value of the belt speed ratio gamma _b in the shift control. Therefore, when the unit speed ratio γ _u matches the target unit speed ratio, the value obtained by multiplying the belt speed ratio γ _b by the output speed matches the turbine speed. The remaining shift speed can be calculated (estimated) from the difference between the current belt speed ratio γ _b multiplied by the output speed and the current turbine speed.

  The turbine rotational speed is the same as the rotational speed of the input shaft 41. Further, since the primary shaft 51 is connected to the input shaft 41 and the primary pulley 53 is supported by the primary shaft 51 so as not to be relatively rotatable, the turbine rotational speed is the same as the primary rotational speed.

  The clutch response time is stored as a constant in the memory of the transmission ECU 12.

  If the remaining shift time is longer than the clutch response time (YES in step S5), execution of the fast fill control is not determined and the fill timing determination process is terminated.

  When the remaining shift time is equal to or shorter than the clutch response time (NO in step S5), execution of the fast fill control is determined (step S4), and the fill timing determination process is terminated. Thus, the engagement of the low clutch C1 can be completed before the shift control is completed.

<Effect>

As described above, when execution of kick-down control that involves switching from the split mode to the belt mode is determined, the change of the belt speed ratio γ _b is started in response to the determination. On the other hand, the sum of the oil flow rate required for changing the belt speed ratio γ _{b and} the oil flow rate required for engaging the low clutch C1 for switching from the split mode to the belt mode is calculated as the required flow rate. The Further, the flow rate of oil discharged from the oil pump 5 is calculated as the supply flow rate. Then, the required flow rate and the supply flow rate are compared, and when the supply flow rate exceeds the required flow rate, supply of hydraulic pressure to the low clutch C1 is started.

As a result, it is possible to suppress the shortage of the oil flow rate, and it is possible to improve the controllability of kick-down control that involves switching from the split mode to the belt mode as the belt speed ratio γ _b is changed.

<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, the required flow rate and the supply flow rate are compared, and when the supply flow rate exceeds the required flow rate, execution of the first fill control is determined. However, when a predetermined margin is added to the required flow rate, the added value is compared with the supply flow rate, and if the supply flow rate exceeds the addition value of the required flow rate and the margin amount, execution of the first fill control is determined. May be. Thereby, it is possible to further suppress the shortage of the oil flow rate, and to further improve the controllability of the kick down control.

  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 2 engine (drive source)
4 power split type continuously variable transmission 5 oil pump 12 transmission ECU (determining means, shift control means, discharge flow rate calculating means, required flow rate calculating means, engagement control means)
41 Input shaft (input shaft)
42 Output shaft (output shaft)
43 continuously variable transmission mechanism 44 constant transmission mechanism 45 output gear mechanism C1 low clutch (engagement element)

Claims (1)

A driving source;
An oil pump driven by the drive source;
An input shaft to which power from the drive source is input, a belt-type continuously variable transmission mechanism that continuously changes power input to the input shaft by changing a belt speed ratio, and power input to the input shaft A constant speed change mechanism that changes speed at a constant split gear ratio; an output gear mechanism that outputs power to the output shaft; and an engagement element that is engaged by a hydraulic pressure generated by the oil pump. Thus, from the split mode in which power input to the input shaft is transmitted to the output gear mechanism via the continuously variable transmission mechanism and the constant transmission mechanism, power input to the input shaft is changed to the continuously variable transmission. A control device for controlling the power split type continuously variable transmission, used in a vehicle equipped with a power split type continuously variable transmission that switches to a belt mode transmitted to the output gear mechanism via a mechanism. Te,
Determining means for determining execution of kickdown control accompanied by switching from the split mode to the belt mode together with the change of the belt speed ratio;
In response to the determination of the execution of the kickdown control, a shift control unit that starts changing the belt speed ratio by controlling the hydraulic pressure supplied to the continuously variable transmission mechanism;
A discharge flow rate calculating means for calculating a flow rate of oil discharged from the oil pump;
A required flow rate calculating means for calculating the sum of the flow rate of oil required for changing the belt speed ratio and the flow rate of oil required for engaging the engagement element;
After the execution of the kickdown control is determined, the flow rate calculated by the discharge flow rate calculation unit is compared with the flow rate calculated by the required flow rate calculation unit, and based on the comparison result, the hydraulic pressure to the engagement element is compared. And an engagement control means for starting supply of the control device.

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