JP2016048100A - Control device of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an automatic transmission which can suitably suppress the vibration of a power transmission system.SOLUTION: When a lockup clutch 20 is in an engagement state, control means 8 for controlling the lockup clutch 20 performs first control which transits the lockup clutch 20 to a first slip engagement state on a start condition that a traveling state detected by traveling state detection means 8d is in a first traveling state which is set as a state that vibration may be generated, and a rotation number is determined to vibrate by vibration determination means 8c, after that, transits the lockup clutch 20 to a second slip engagement state in which a slip amount is smaller than that in the first slip engagement state, and when it is determined that the rotation number does not vibrate by the vibration determination means 8c in the second slip engagement state, transits the lockup clutch 20 to a third slip state in which the slip amount is smaller than that in the second slip engagement state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a device for controlling a lock-up clutch provided in a torque converter of an automatic transmission.

  2. Description of the Related Art Conventionally, an automatic transmission including a torque converter provided with a lockup mechanism has been put to practical use as a transmission installed in a vehicle. In the torque converter, if the lockup mechanism is engaged, the input side (pump side) and the output side (turbine side) are directly connected to transmit power directly, and the lockup mechanism is disengaged. Then, power is transmitted indirectly through the fluid. This lock-up mechanism is engaged or released under various conditions.

  For example, Patent Document 1 discloses a rotational speed region (hereinafter referred to as “resonant rotational speed region”) in which the rotational speed (rotational speed) of the input shaft in the transmission corresponds to the resonant frequency region of the power transmission system (drive system) of the vehicle. Techniques have been proposed for disengaging the lockup mechanism when it is within. Thereby, generation of noise due to vibration of the power transmission system can be suppressed.

JP 2011-1913 A

  However, in the technique as disclosed in Patent Document 1, since the lockup mechanism is uniformly disengaged if the input rotational speed of the transmission is within the resonance rotational speed range, the vibration of the power transmission system is actually caused. Since power is transmitted only by the torque converter even in a situation where it does not occur, the fuel consumption may be reduced, and the drivability may be reduced due to the reduction in direct feeling.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a control device for an automatic transmission that can appropriately suppress vibration of a power transmission system. Note that the present invention is not limited to this purpose, and other effects of the present invention can also be achieved by the functions and effects derived from the respective configurations shown in the embodiments for carrying out the invention which will be described later. Can be positioned as

  (1) In order to achieve the above object, an automatic transmission control device according to the present invention is engaged in a torque converter provided in a power transmission system between a prime mover that is a drive source of a vehicle and a drive wheel. And a lock-up clutch capable of achieving any one of a released state and a slip engagement state, a rotational speed sensor for detecting the rotational speed of a rotary shaft provided in the power transmission system, and the rotational speed sensor Vibration determining means for determining whether or not the number of rotations is oscillating, traveling state detecting means for detecting the traveling state of the vehicle, and control means for controlling the lock-up clutch. When the lockup clutch is in the engaged state, the traveling state detected by the traveling state detecting means is a first traveling state that is preset as a state where the vibration can occur. The lockup clutch is shifted to the first slip engagement state on the condition that the vibration determination means determines that the rotational speed is oscillating, and then the lockup clutch is moved to the first slip engagement state. When the transition is made to the second slip engagement state in which the slip amount is smaller than that in the slip engagement state, and the vibration determination means determines that the rotation speed is not vibrated in the second slip engagement state, the lock The first control is performed to shift the up clutch to a third slip engagement state in which the slip amount is smaller than that in the second slip engagement state.

  (2) Termination of transition of the lockup clutch from the slip engagement state to the engagement state on the condition that the travel state detected by the travel state detection means is not the first travel state. It is preferable to implement transition control.

(3) A gear ratio detecting means for detecting a gear ratio is provided, and the control means fluctuates a gear ratio detected by the gear ratio detecting means when the start condition is satisfied by a predetermined amount or more. It is preferable to implement end transition control for shifting the lockup clutch from the slip engagement state to the engagement state under the end condition.
(4) The control means determines that the number of rotations is not oscillating by the vibration determination means, and the traveling state detected by the traveling state detection means further includes the vibration in the first traveling state. The lock-up clutch is shifted to the first slip engagement state on the condition that the second running state is set in advance as a state in which it is likely to occur, and then the lock-up clutch is moved to the first slip engagement state. It is preferable to implement the second control for shifting to the second slip engagement state in which the slip amount is smaller than that in the slip engagement state.

(5) When the start condition is satisfied in the first control, the control means shifts the lock-up clutch to the first slip engagement state with a preset first release degree. It is preferable to implement 1 start transition control.
(6) When the start condition is satisfied in the second control, the control means engages the lock-up clutch with the first slip engagement with a second release degree smaller than the first release degree. It is preferable to implement the second start transition control for shifting to the state.

  (7) In the second start transition control, the control means causes the vibration determination means to change the rotation speed while the lockup clutch is shifted to the first slip engagement state at the second release degree. When it is determined that the first control is started and the first control start condition is satisfied, the second release degree is changed to the first release degree, and the lockup clutch is brought into the first slip engagement state. It is preferable to shift to the first start shift control to be transferred.

According to the control apparatus for an automatic transmission of the present invention, the control means sets the lock-up clutch to the first when the vibration determination means determines that the rotation speed of the rotary shaft provided in the power transmission system is vibrating. Therefore, the vibration of the rotational speed of the rotary shaft provided in the power transmission system can be reliably absorbed by the lock-up clutch that functions as a damper. In addition, since the lockup clutch is not completely released and is maintained in the slip engagement state, it is possible to suppress a decrease in power transmission efficiency.
Thereafter, the control means shifts the lock-up clutch in the first slip engagement state to the second slip engagement state in which the slip amount is smaller than that in the first slip engagement state. The vibration of the power transmission system can be absorbed while being suppressed.
When the vibration determining means determines that the rotation speed is not oscillating (stable), the control means slips the lock-up clutch in the second slip engagement state further than in the second slip engagement state. Since the transition to the third slip engagement state with a small amount is made, it is possible to prevent the power transmission efficiency from being lowered, to ensure the durability of the lockup clutch, and to reliably suppress the vibration of the power transmission system. Also contributes.
In this way, the control means performs the first control that gradually reduces the slip amount of the lockup clutch in the order of the first, second, and third slip engagement states. It is possible to suppress a decrease in drivability due to a decrease in direct feeling, and to reliably absorb vibrations in the power transmission system.
Absorption of vibration in the power transmission system by the first control that shifts the lock-up clutch to the first to third slip engagement states may cause vibration of the power transmission system when the lock-up clutch is in the engagement state. Since the start condition is that the vehicle is in the first traveling state set in advance as the state, the vibration of the power transmission system can be appropriately suppressed.

1 is an overall configuration diagram illustrating a power transmission system and a control system of a vehicle to which a control device for an automatic transmission according to an embodiment of the present invention is applied. It is a map used for determination of the running state of the vehicle by the control apparatus of the automatic transmission concerning one Embodiment of this invention. In this map, the horizontal axis is the vehicle speed, and the vertical axis is the turbine speed. It is a time chart which illustrates temporal change of the oil pressure of the 1st LUC control by the control device of the automatic transmission concerning one embodiment of the present invention. It is a time chart which illustrates the time-dependent change of the oil pressure of the 2nd LUC control by the control device of the automatic transmission concerning one embodiment of the present invention. It is a time chart which illustrates temporal change of oil pressure when changing from the 1st LUC control to the 2nd LUC control by the control device of an automatic transmission concerning one embodiment of the present invention. It is a flowchart which shows the whole control by the control apparatus of the automatic transmission concerning one Embodiment of this invention. It is a flowchart which shows the subroutine of the 1st start transfer control implemented by the control apparatus of the automatic transmission concerning one Embodiment of this invention. It is a flowchart which shows the subroutine of the 1st slip control implemented by the control apparatus of the automatic transmission concerning one Embodiment of this invention. It is a flowchart which shows the subroutine of the 2nd start transfer control implemented by the control apparatus of the automatic transmission concerning one Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a control device for an automatic transmission according to the present invention will be described with reference to the drawings. In the present embodiment, a belt type continuously variable transmission (also referred to as “belt type CVT” or simply “CVT”) is applied as an automatic transmission. However, as the automatic transmission, other continuously variable transmissions such as toroidal CVT and chain type CVT, and stepped transmissions can be applied. The “rotation speed” in the present embodiment is a rotation amount per unit time and corresponds to the rotation speed. “Rotational speed vibration” means fluctuations in angular velocity.

[I. One Embodiment]
Hereinafter, a control apparatus for an automatic transmission according to an embodiment will be described.
[1. Constitution〕
The control device for the automatic transmission targets a belt type continuously variable transmission provided in the power transmission system of the vehicle.

[1-1. (Power transmission system)
First, the configuration of a vehicle power transmission system will be described with reference to FIG.
The power transmission system of the vehicle includes an engine (prime mover) 1, a belt type continuously variable transmission (CVT) 100, a final reduction mechanism 5, and drive wheels 6 and 6. In the belt-type continuously variable transmission 100, a torque converter 2, a forward / reverse switching mechanism 3, and a belt-type continuously variable transmission mechanism (also referred to as "variator") 4 are accommodated in a transmission case.

[1-1-1. engine〕
The engine 1 is a drive source for the vehicle. Here, an internal combustion engine is applied as the engine 1. Instead of the engine 1, for example, another drive source such as a hybrid drive source having both an electric motor and an engine or an electric drive source of a single electric motor may be applied.

[1-1-2. (Torque converter)
The torque converter 2 is a starting element having a torque increasing function, and a lock-up clutch capable of directly connecting the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 when the torque increasing function is not required. 20 is provided. The torque converter 2 is provided with a pump impeller 23 connected to the engine output shaft 11 via a converter housing 22, a turbine runner 24 connected to the torque converter output shaft 21, and a case via a one-way clutch 25. The stator 26 is a constituent element.

The lock-up clutch 20 is in an engaged state (clutch fully engaged state), a released state (clutch fully released state), a slip engaged state (clutch slip engaged state, that is, in accordance with the running state and driving state of the vehicle. The state in which torque is transmitted from the input side to the output side although there is a difference in the number of rotations of the rotation member on the input side of the lock-up clutch 20 and the rotation member on the output side) Achievable.
If the lock-up clutch 20 is in the slip engagement state, a part of the power is transmitted through the torque converter 2, so that the power is transmitted with a rotational difference between the input and output shafts. For this reason, the lock-up clutch 20 in the slip engagement state functions as a damper in the power transmission system.

  By controlling the hydraulic pressure supplied to the lockup clutch 20, the state of the lockup clutch 20 is switched. Further, by controlling the supply hydraulic pressure, the clutch engagement force in each state of the lockup clutch 20, that is, the torque transmission capacity of the clutch is also controlled. The supplied hydraulic pressure (hereinafter also referred to as “lock-up engagement pressure”) is a differential pressure between two oil chambers (not shown) before and after the lock-up clutch 20, that is, the torque converter supply pressure Pa in the apply chamber and the release chamber. Is the differential pressure (lockup differential pressure) ΔP (= Pa−Pr) of the torque converter release pressure Pr.

[1-1-3. Forward / reverse switching mechanism)
The forward / reverse switching mechanism 3 is a mechanism that switches the input rotation direction of the belt-type continuously variable transmission mechanism 4 to the transmission mechanism input shaft 40 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. The forward switching mechanism 3 includes a double pinion type planetary gear 30, a forward clutch 31 and a reverse brake 32 including a plurality of clutch plates.

The forward clutch 31 is engaged by the forward clutch pressure Pfc when a forward travel range such as the D range (drive range) is selected. The reverse brake 32 is engaged by the reverse clutch pressure Prb when the R range (reverse range) that is the reverse travel range is selected. When the N range (neutral range, non-traveling range) is selected, both the forward clutch pressure Pfc and the reverse brake pressure Prb are drained, and both the forward clutch 31 and the reverse brake 32 are released.
As the forward / reverse switching mechanism 3, a mechanism having a function as an auxiliary transmission mechanism that can achieve a plurality of shift speeds on the forward side may be applied.

[1-1-4. Continuously variable transmission mechanism)
The belt-type continuously variable transmission mechanism 4 has a continuously variable transmission function that changes the transmission ratio steplessly by changing the belt contact diameter. The belt type continuously variable transmission mechanism 4 includes a primary pulley 42, a secondary pulley 43, and a belt 44. The primary pulley 42 has a fixed pulley 42 a and a slide pulley 42 b, and the slide pulley 42 b moves in the axial direction by a primary pressure Ppri guided to the primary pressure chamber 45. Similarly, the secondary pulley 43 has a fixed pulley 43 a and a slide pulley 43 b, and the slide pulley 43 b moves in the axial direction by the secondary pressure Psec guided to the secondary pressure chamber 46.

  The sheave surfaces that are the opposing surfaces of the fixed pulley 42a and the slide pulley 42b of the primary pulley 42 and the sheave surfaces that are the opposing surfaces of the fixed pulley 43a and the slide pulley 43b of the secondary pulley 43 are all V-shaped. ing. These sheave surfaces come into contact with the flank surfaces on both sides of the belt 44. The gear ratio is changed by changing the winding radius of the belt 44 around the primary pulley 42 and the secondary pulley 43 according to the axial movement of the slide pulleys 42b and 43b.

[1-1-5. Final deceleration mechanism)
The final deceleration mechanism 5 is a mechanism that decelerates the output rotation from the transmission mechanism output shaft 41 of the belt-type continuously variable transmission mechanism 4 and transmits it differentially to the left and right drive wheels 6 and 6. The final reduction mechanism 5 is interposed between the transmission mechanism output shaft 41 and the left and right drive shafts 51, 51 connected to the drive wheels 6, 6, and a first gear 52 provided on the transmission mechanism output shaft 41. And a second gear 53 and a third gear 54 provided on the idler shaft 50, and a differential gear 56 connected through a final reduction gear 55 and having a differential function.

[1-2. Control system)
Next, the configuration of the vehicle control system will be described. Here, a description will be given focusing on a control system for controlling the belt type continuously variable transmission 100.
The vehicle control system is provided with a hydraulic control unit 7 and a CVT electronic control unit (hereinafter referred to as “CVTECU”, control means) 8. The hydraulic pressure control unit 7 generates a hydraulic pressure corresponding to the command pressure output from the CVTECU 8. In addition, an engine electronic control unit (hereinafter referred to as “engine ECU”) 9 for exchanging information with the CVTECU 8 is provided. The engine ECU 9 controls a wide range of systems related to the engine 1 such as an ignition system, a fuel system, an intake / exhaust system, and a valve system. Each of the electronic control units (ECUs) 8 and 9 includes an input / output device, a storage device (ROM, RAM, etc.) incorporating a number of control programs, a central processing unit (CPU), a timer counter, and the like. Configured.

[1-2-1. Hydraulic control unit)
The hydraulic control unit 7 includes a primary pressure Ppri guided to the primary pressure chamber 45, a secondary pressure Psec guided to the secondary pressure chamber 46, a forward clutch pressure Pfc to the forward clutch 31, and a reverse brake pressure Prb to the reverse brake 32. And the solenoid pressure Psol to the lock-up control valve 78. The hydraulic control unit 7 includes an oil pump 70 and a hydraulic control circuit 71.

The hydraulic control circuit 71 includes a line pressure solenoid 72, a primary pressure solenoid 73, a secondary pressure solenoid 74, a forward clutch pressure solenoid 75, a reverse brake pressure solenoid 76, and a lockup solenoid 77.
The line pressure solenoid 72 adjusts the hydraulic oil pumped from the oil pump 70 to the instructed line pressure PL in response to the line pressure instruction output from the CVT ECU 8.
The primary pressure solenoid 73 adjusts the pressure to the primary pressure Ppri instructed by using the line pressure PL as the original pressure in response to the primary pressure instruction output from the CVTECU 8.

The secondary pressure solenoid 74 adjusts the pressure to the secondary pressure Psec instructed with the line pressure PL as the original pressure in response to the secondary pressure instruction output from the CVTECU 8.
The forward clutch pressure solenoid 75 adjusts the pressure to the forward clutch pressure Pfc instructed with the line pressure PL as the original pressure in response to the forward clutch pressure instruction output from the CVT ECU 8.
The reverse brake pressure solenoid 76 adjusts the pressure to the reverse brake pressure Prb instructed by using the line pressure PL as the original pressure in response to the reverse brake pressure instruction output from the CVT ECU 8.

  The lockup solenoid 77 generates a solenoid pressure Psol as an instruction signal pressure to the lockup control valve 78 in accordance with an instruction from the CVTECU 8. The lockup control valve 78 uses a solenoid pressure Psol as an operation signal pressure, and a lockup differential pressure ΔP (ΔP = Pa−Pr), which is a differential pressure between the front and rear oil chambers of the lockup clutch 20, is a value based on an instruction from the CVTECU 8. The torque converter supply pressure and the torque converter discharge pressure are adjusted so that

[1-2-2. CVTECU]
As described above, the CVT ECU 8 outputs each command pressure related to the CVT 100 to control a wide range of systems related to the CVT 100. In the following description, focusing on the control of the lock-up clutch 20 of the torque converter 2, the configuration of the CVT ECU 8 Is described in detail.
Various sensors are connected to the CVTECU 8 via a communication line such as CAN or FlexRay. Information detected by various sensors is transmitted to CVT ECU 8.

[1-2-2-1. Sensors)
First, various sensors connected to the CVT ECU 8 will be described.
The line pressure sensor 80 detects the line pressure PL, the primary pressure sensor 81 detects the primary pressure Ppri, and the secondary pressure sensor 82 detects the secondary pressure Psec. Based on the detection information of these sensors 80, 81, 82, the CVTECU 8 calculates and outputs the indicated pressure of each hydraulic pressure.

  The engine rotational speed sensor 83 detects the rotational speed of the engine output shaft 11, and the primary rotational speed sensor 84 (traveling state detecting means) detects the rotational speed of the primary pulley 42 (= the rotational speed of the transmission mechanism input shaft 40). The secondary rotational speed sensor 85 (traveling state detecting means) detects the rotational speed of the secondary pulley 43 (= the rotational speed of the transmission mechanism output shaft 41). Note that the primary rotational speed sensor 84 may detect the rotational speed of the turbine runner 24 instead of detecting the rotational speed of the primary pulley 42.

  The CVTECU 8 calculates (detects) a gear ratio that is a ratio between the rotation speed of the primary pulley 42 detected by the primary rotation speed sensor 84 and the rotation speed of the secondary pulley 43 detected by the secondary rotation speed sensor 85. Functions as a means. The CVTECU 8 also calculates the vehicle speed from the calculated gear ratio and the rotational speed detected by the primary rotational speed sensor 84. Here, information on the rotational speed of the engine output shaft 11 detected by the engine rotational speed sensor 83 is transmitted to the CVTECU 8 via the engine ECU 9.

The inhibitor switch (inhibitor SW) 86 is a sensor that detects a range position (P range, R range, N range, D range, etc.) selected by the driver's shift lever operation.
The accelerator opening sensor 87 detects an amount of depression of an accelerator pedal (not shown). The idle switch (idle SW) 88 detects whether or not the accelerator pedal is depressed. The idle switch 88 outputs an OFF signal when the accelerator pedal is depressed, and outputs an ON signal when the accelerator pedal is not depressed.

  The brake switch (brake SW) 89 detects whether or not an unillustrated brake pedal is depressed. The brake switch 89 outputs an ON signal when the brake pedal is depressed, and outputs an OFF signal when the pedal is not depressed.

[1-2-2-2. Each functional element of CVT ECU]
Next, the control (hereinafter referred to as “LUC control”) for bringing the lock-up clutch 20 into the slip engagement state, which is performed by the CVTECU 8, will be described. Here, in the LUC control, the first LUC control (first control) that is executed when the vibration of the power transmission system is determined (detected) and the vibration of the power transmission system are likely to occur. Two controls, the second LUC control (second control), will be described. The first LUC control and the second LUC control are performed to suppress vibration of the power transmission system.

The CVT ECU 8 includes a precondition determination unit 8A, a vibration determination unit (vibration determination unit) 8c, and a travel state determination unit (travel state determination unit) 8d as functional elements for the first LUC control and the second LUC control. Unit 8B, a first LUC control unit 8E, a second LUC control unit 8F, and an end condition determination unit 8G.
When the precondition is determined by the precondition determining unit 8A and the start condition is determined by the start condition determining unit 8B, the CVTECU 8 is first controlled by the first LUC control unit 8E or the second LUC control unit 8F. The 1LUC control or the second LUC control is alternatively performed, and when the end condition determining unit 8G determines that the end condition is satisfied, the first LUC control or the second LUC control is ended.

In a 1LUC control or the 2LUC control, but controls the lock-up engagement pressure P _LU (= lock-up differential pressure [Delta] P), indicated value T _LU engagement capacity the torque transmitting capacity of the lock-up clutch 20 (hereinafter, The engagement capacity T _LU is simply obtained periodically, and an engagement pressure command value P _LU (hereinafter simply referred to as engagement pressure) of the lock-up clutch is controlled by open loop control according to the engagement capacity T _LU. also referred to as) to control the P _LU.

Note that the engagement capacity T _LU and the engagement pressure P _{LU of the} lockup clutch 20 have a relationship in which the engagement capacity T _LU increases (for example, increases linearly) as the engagement pressure P _LU increases. By preparing a map based on this relationship, the engagement capacity T _LU can be converted into the engagement pressure P _LU with reference to the conversion map. Then, convert the engagement pressure P _LU obtained the command value of the lock-up solenoid 77 (lockup duty), controls the lock-up solenoid 77 by the command value, to control the state of the lock-up clutch 20.

[Prerequisite judgment section]
The precondition determining unit 8A determines a precondition (precondition) for performing the first LUC control and the second LUC control. The precondition referred to here can be said to be a part of the conditions (permission conditions) for permitting the CVTECU 8 to perform the first LUC control and the second LUC control.

<Prerequisites for the first LUC control>
First, preconditions for the first LUC control (hereinafter referred to as “first preconditions”) will be described.
The first precondition is satisfied, for example, when all of the following (A1) to (A4) apply.
(A1) All the various sensors are normal.
(A2) The accelerator operation is performed.
(A3) The D range is selected.
(A4) The lockup clutch 20 is in an engaged state.

The above (A1) holds if no fail signal or abnormal output value is output from various sensors.
The above (A2) is established if the idle switch 88 outputs an OFF signal. This (A2) may be established when the accelerator pedal depression amount from the accelerator opening sensor 87 is larger than a predetermined amount near zero. In addition to (A2), it may be included that the brake switch 89 outputs an OFF signal.

The above (A3) is established when the range position detected by the inhibitor switch 86 is the D range.
The above (A4) can be determined based on the solenoid pressure Psol which is an instruction signal pressure from the CVT ECU 8. Further, (A4) can be determined to be established when the difference between the rotational speed detected by the engine rotational speed sensor 83 and the rotational speed detected by the primary rotational speed sensor 84 is smaller than the predetermined rotational speed. . This is because the detection errors of the sensors 83 and 84 are taken into consideration, and the lock-up clutch 20 at this time is substantially engaged.

Note that the following (A5) and (A6) may be added to the first precondition.
(A5) The accelerator opening is not less than a predetermined opening.
(A6) If a sub-transmission mechanism is provided in the power transmission system, (A61) the sub-transmission mechanism is in the first speed stage or the second speed stage, (A62) rotation on the input side and output side of the sub transmission mechanism. (A63) The sub-transmission mechanism is not being shifted (being replaced).

<Prerequisites for second LUC control>
The preconditions for the second LUC control (hereinafter referred to as “second preconditions”) are the same as the first preconditions.

[Start condition judgment unit]
The start condition determination unit 8B determines the start conditions of the first LUC control and the second LUC control. The start condition here is a trigger for starting the first LUC control and the second LUC control.
This start condition is determined using the vibration determination unit 8c and the running state determination unit 8d of the start condition determination unit 8B.

  The vibration determination unit 8c determines whether or not the rotational speed of the rotary shaft provided in the power transmission system vibrates (vibration of the power transmission system). For example, the rotational speed of the secondary pulley 43 detected by the secondary rotational speed sensor 85 (= the rotational speed of the transmission mechanism output shaft 41) or the rotational speed of the primary pulley 42 detected by the primary rotational speed sensor 84 (= transmission mechanism input shaft). It is determined whether the rotational speed of 40 = the rotational speed of the turbine runner 24 is oscillating. At this time, the vibration determination unit 8c also calculates the vibration frequency of the power transmission system.

  As a method for determining the vibration by the vibration determination unit 8c, a method using a bandpass process for the detected number of rotations may be used. For example, bandpass processing is performed on the detected number of revolutions, and the bandpass-processed value (hereinafter referred to as “bandpass processing value”) is a predetermined range of change in a predetermined number of revolutions, that is, a predetermined number of revolutions. It is determined whether or not the band (hereinafter referred to as “first predetermined rotation speed change range”) is entered, and if the bandpass processing value is not in the first predetermined rotation speed change range, that is, the first If the fluctuation width of the rotation speed is large so as to protrude the predetermined rotation speed change region, it is determined that the vibration is occurring. Further, it is possible to detect the timing at which the band pass processing value exceeds the first predetermined rotation speed change range to the high speed side and the low speed side, respectively, and calculate the frequency of the rotation speed that fluctuates based on this timing as the vibration frequency. . If the calculated vibration frequency is within a predetermined frequency range from the natural resonance frequency corresponding to the gear ratio at the time of detection, it can be determined that the power transmission system is resonating (vibrating). If it is determined that the power transmission system is resonating, the vibration determination unit 8c may determine that the rotational speed of the rotary shaft provided in the power transmission system is vibrating.

  The traveling state determination unit 8d determines whether the traveling state of the vehicle is in a predetermined traveling state. Here, the transmission ratio and the rotational speed of the rotary shaft provided in the power transmission system (here, the rotational speed of the turbine runner 24, hereinafter referred to as “turbine rotational speed”) N are used as parameters representing the running state of the vehicle. .

  By the way, the power transmission system of a vehicle has a specific resonance frequency corresponding to the gear ratio on a one-to-one basis. When the power transmission system is in a directly connected state, vibration may occur at a specific resonance frequency or its peripheral frequency. In particular, when the turbine rotational speed N is within a predetermined rotational speed range, vibration is likely to occur in the power transmission system at the natural resonance frequency or its peripheral frequency. Further, when the gear ratio is within the predetermined gear ratio range, vibration of the power transmission system is more likely to occur.

Therefore, as shown in the map of FIG. 2, the turbine speed N is within a predetermined range (N ₁ <N <N ₂ ), and the gear ratio r is within a predetermined range (r ₁ <r <r ₄ ). In the region B (first running state), vibration of the power transmission system is likely to occur. Further, in the region B, the vibration of the power transmission system is more likely to occur in the region A (second traveling state) within the gear ratio range (r ₂ <r <r ₃ ). These areas A and B are set in advance experimentally or empirically.
That is, the traveling state determination unit 8d determines whether the traveling state of the vehicle is included in the region A or the region B based on the turbine rotational speed N detected by the primary rotational speed sensor 84 and the calculated gear ratio r. Determine.

<First LUC control start condition>
First, the start condition of the first LUC control (hereinafter referred to as “first start condition”) will be described.
The first start condition is satisfied when, for example, the following (B1) and (B2) are satisfied.
(B1) The vibration of the power transmission system is determined.
(B2) The traveling state of the vehicle is in region B.

The (B1) is determined by the vibration determining unit 8c, and the (B2) is determined by the traveling state determining unit 8d.
Note that the following (B3) may be added to the (B1) of the first start condition.
(B3) The frequency of the vibration detected in (B1) is within a predetermined frequency range from the natural resonance frequency corresponding to the gear ratio at the time of detection.

  If (B3) applies, it can be determined that the power transmission system is resonating (vibrating) as described above. By adding (B3) to (B1) above, unnecessary LUC when the detected vibration frequency is not caused by the natural resonance frequency of the power transmission system (not the resonance of the power transmission system). It is possible to prevent the control from being performed, to suppress a decrease in fuel consumption, and to ensure the durability of the facing of the lockup clutch 20.

<Conditions for starting the second LUC control>
Next, the start condition of the second LUC control (hereinafter referred to as “second start condition”) will be described.
The second start condition is satisfied when at least the following (C1) and (C2) are met.
(C1) The running state of the vehicle is in region A.
(C2) The first start condition is not satisfied.

Thus, the second start condition does not require that there is vibration of the power transmission system. Note that (C1) is determined by the traveling state determination unit 8d.
Since (C2) is included in the second start condition, the first LUC control is performed with priority over the second LUC control.

[First LUC control unit]
The first LUC control unit 8E performs first LUC control. In the first LUC control, a first start transition control at the start of control, a first slip control for bringing the lock-up clutch 20 into a slip engagement state, and a first end transition control at the end of the control are performed.

<First start transition control>
The first start transition control is performed when the first start condition is satisfied. In the first start transition control, the locked-up clutch 20 in the engaged state is gradually shifted toward the slip engaged state in order to suppress a sudden change in torque fluctuation.

Speaking in detail, the first start transition control, as shown in FIG. 3, at time t _11, it is reduced stepwise to give the initial value to the engagement pressure P _LU (the smooth off initial value), then ramp-shaped Gradually decrease (smooth off). The smooth-off initial value is set to such a magnitude that the locked-up clutch 20 in the engaged state is in a state just before the transition to the slip engaged state.

In the process of gradually decreasing the engagement pressure P _LU at time t ₁₁ ~t ₁₂ in a ramp form (lamp control), such that the first differential rotation α which differential rotation of the torque converter 2 is preset as a target rotational speed difference, The lockup clutch 20 is gradually brought into the first slip engagement state with a preset first release degree.
The first release degree corresponds to the decrease of the engagement pressure P _LU per unit time (slope of the engagement pressure P _LU during lamp control in FIG. 3).

The first slip engagement state is a state where the differential rotation of the torque converter 2 is the first differential rotation α. Engagement pressure P _LU in this state, a lower oil pressure than the reference engagement pressure P _LUS corresponding to the boundary between the engaged state and the slip engagement state. When the lockup clutch 20 is in the first slip engagement state, the first start transition control is completed.

<First slip control>
The first slip control is performed after the completion of the first start transition control. In the first slip control, the first drive slip control and the first micro slip control are performed.

<First drive slip control>
The first drive slip control is performed when the first start transition control is completed. In the first drive slip control, as shown at time points t _{12 to} t ₁₃ in FIG. 3, the lockup clutch 20 is shifted to the second slip engagement state in which the slip amount is smaller than that in the first slip engagement state. .
In the first drive slip control, so that the difference rotation of the torque converter 2 is a second differential rotation β which is set in advance lower than the alpha rotating first difference of the (<alpha), the feedback control of the engagement pressure P _LU To do. At this time, control is performed so that the change rate of the differential rotation of the torque converter 2 does not exceed the preset differential rotation change rate Δβ.

The second slip engagement state is a state where the differential rotation of the torque converter 2 becomes a preset second differential rotation β. The engagement pressure P _{LU in} this state is lower than the reference engagement pressure P _{LUS and} higher than the engagement pressure P _{LU in} the first slip engagement state.
The first drive slip control is completed when a vibration of the power transmission system is not detected (determined as not oscillating) by the vibration determination unit 8c, that is, when the differential rotation of the torque converter 2 is stabilized. Specifically, the bandpass processing value of the detected rotation speed is smaller than the first predetermined rotation speed change area, and the predetermined rotation speed change area, that is, a predetermined rotation speed band (hereinafter, “ It is determined whether or not it is in a second predetermined rotation speed change range), and if the bandpass processing value is in the second predetermined rotation speed change area, vibration is not detected, that is, vibration is detected. First drive slip control is completed.

<First micro slip control>
The first micro slip control is started when the first drive slip control is completed. In the first micro-slip control, as shown at time points t _{13 to} t ₁₄ in FIG. 3, the lock-up clutch 20 is shifted to the third slip engagement state in which the slip amount is smaller than that in the second slip engagement state. Let

In the first micro-slip control, so that the third differential rotation γ of the differential rotation of the torque converter 2 is set smaller than the second differential rotation beta, feedback control of the engagement pressure P _LU. At this time, control is performed so that the rate of change of the differential rotation of the torque converter 2 does not exceed a preset differential rotation rate of change Δγ.

The third slip engagement state is a state in which the differential rotation of the torque converter 2 becomes a preset third differential rotation γ. The engagement pressure P _{LU in} this state is slightly lower than the reference engagement pressure P _{LUS and} higher than the engagement pressure P _{LU in} the second slip engagement state.
The first micro slip control is ended when a first end condition described later is satisfied. If the vibration determination unit 8c detects vibration of the power transmission system during the execution of the first micro slip control, the first micro slip control is terminated and the first drive slip control is performed again. The

<First end transition control>
The first end transition control is performed when a first end condition described later is satisfied. In this first end transition control, as shown at time points t _{14 to} t ₁₅ in FIG. 3, in order to suppress a sudden change (engagement shock) in torque fluctuation, the lock-up clutch 20 in the slip engagement state is turned to the engagement state. To gradually shift (smooth on). That is, to gradually increase the engagement pressure P _LU in a ramp shape, the differential rotation of the torque converter 2 is eliminated or to shift to the engaged state of the lock-up clutch 20 which substantially eliminated.

[Second LUC control unit]
The second LUC control unit 8F performs the second LUC control. In the second LUC control, a second start transition control at the start of control, a second slip control for bringing the lock-up clutch 20 into a slip engagement state, and a second end transition control at the end of the control are performed.

<Second start transition control>
The second start transition control is performed when the second start condition is satisfied. The second start transition control has the same control content as the first start transition control except that the degree of release in lamp control is different.
In the second start transition control, as shown from the time point t ₂₁ to the time point t ₂₂ in FIG. 4, the lock-up clutch 20 is gradually brought into the slip engagement state with the second release degree set in advance in the ramp control. The second release degree is set smaller than the first release degree. That is, (the slope of the engagement pressure P _LU during ramp control of Figure 4) Figure decrease in the engagement pressure P _LU per unit time during the ramp control of 4, the unit in the ramp control of the first start transition control time decrease of the engagement pressure P _LU per (Figure 4 indicated by the two-dot chain line) is smaller than.

Here, the differential rotation α ′ is used as the target differential rotation of the torque converter 2 in the second start transition control. The first differential rotation α ′ is the same as the first differential rotation α of the first start transition control, but may be larger or smaller than this.
Similar to the first start transition control, the second start transition control is completed when the first slip engagement state in which the differential rotation of the torque converter 2 becomes the first differential rotation α ′.

<Second slip control>
Second slip control, as shown in time point t ₂₂ ~ time t ₂₃ of FIG. 4, is performed after completion of the second start transition control. In the second slip control, second drive slip control is performed. In the second slip control, the control corresponding to the first micro slip control is not performed.

<Second drive slip control>
The second drive slip control ends when a second end condition described later is satisfied. The second drive slip control can have the same control content as the first drive slip control. However, here, in the second drive slip control, the second differential rotation β ′ (<< smaller than the first differential rotation α ′ and smaller than the second differential rotation β in the target differential rotation of the torque converter 2. alpha 'uses a), the second differential rotation beta' has reduced the engagement pressure P _LU so as not to exceed the preset differential rotation change rate [Delta] [beta] 'corresponds to.

The reason why the second differential rotation β ′ smaller than the second differential rotation β is used for the target differential rotation of the torque converter 2 is that the second drive slip control does not require vibration of the power transmission system. That is, in the situation where the second drive slip control is performed, no vibration is generated in the power transmission system, so even if the target differential rotation is reduced, the differential rotation suddenly fluctuates due to the vibration and the lockup clutch 20 is suddenly moved. There is little risk of engagement. For this reason, it is possible to suppress the deterioration of the power transmission efficiency, to suppress the deterioration of the facing of the lockup clutch 20, and to contribute to reliably suppressing the vibration of the power transmission system.
Similar to the first drive slip control, the second drive slip control is completed when the second slip engagement state in which the differential rotation of the torque converter 2 becomes the second differential rotation β ′.

<Second end transition control>
Second termination transition control, as shown in time point t ₂₃ ~ time t ₂₄ in FIG. 4, the second slip control is performed after completion. The second end transition control can have the same control content as the first end transition control. However, the first ends transition control is also possible to employ the increasing degree of different engagement pressure P _LU.

[End condition judgment unit]
The end condition determination unit 8G determines the end conditions of the first LUC control and the second LUC control. Note that the termination condition referred to here can also be said to be a condition (prohibition condition) for prohibiting the CLUTECU 8 from performing the first LUC control and the second LUC control.

<First LUC control termination condition>
An end condition of the first LUC control (hereinafter referred to as “first end condition”) will be described.
The first termination condition is satisfied when, for example, at least one of the following (D1) to (D3) is satisfied.
(D1) The first precondition is not satisfied.
(D2) The first start condition is not satisfied.
(D3) The gear ratio at the time when the first start condition is satisfied fluctuates to a predetermined amount or more.

  If any one of the first preconditions is not satisfied, the condition (D1) is satisfied. Similarly, if any one of the first start conditions is not satisfied, the condition (D2) is satisfied. For example, it is preferable to determine whether or not the traveling state according to the above (B2), which is one of the first start conditions, is in the region B, has hysteresis to prevent hunting.

The predetermined amount of (D3) is a threshold value for determining whether or not the vibration is oscillating at the natural resonance frequency corresponding to the transmission ratio on a one-to-one basis or the surrounding frequency. Can be adopted. For example, a map in which the vertical axis represents frequency and the horizontal axis represents the gear ratio is set, a predetermined frequency range is set to the frequency when the first start condition is satisfied, and the upper and lower limits of the predetermined frequency range are handled. If the speed ratio is out of the range, it can be determined that the speed ratio has fluctuated more than a predetermined amount.
The following (D4) or the like may be added to the first end condition.
(D4) A predetermined time or more has elapsed since the first LUC control was started.
This (D4) is effective for suppressing control retention.

<Termination condition for second LUC control>
Next, the end condition of the second LUC control (hereinafter referred to as “second end condition”) will be described.
The second end condition is satisfied when at least one of the following (E1) and (E2) is true.
(E1) The second precondition is not satisfied.
(E2) The second start condition is not satisfied.

If any one of the second preconditions is not satisfied, the condition (E1) is satisfied. Similarly, if any one of the second start conditions is not satisfied, the condition (E2) is satisfied. For example, the determination as to whether or not the traveling state of (C1), which is one of the second start conditions, is in the region A is preferably provided with hysteresis to prevent hunting.
Note that, as in the first end condition (D4), (E3) that a predetermined time or more has elapsed since the start of the second LUC control may be added to the second end condition.

<Control transfer when termination condition is satisfied>
During the first LUC control, for example, when the first end condition is satisfied under (D3) above, but the vehicle is in the region A and the second end condition is not satisfied (when the second start condition is satisfied). The first LUC control is shifted to the second LUC control. For example, when the first end condition is satisfied during the execution of the first start transition control of the first LUC control but the second end condition is not satisfied (if the second start condition is satisfied), the lockup clutch 20 is released. The degree is changed from the first release degree to the second release degree smaller than this, and the process proceeds to the second start transition control.

Further, during the second LUC control, when the second end condition is satisfied but the first end condition is not satisfied (for example, when the first start condition is satisfied by the vibration determination), the second LUC control is changed to the first LUC control. Transition. For example, as shown in FIG. 5, when the second start transition control of the 2LUC control from the time t ₃₁ is performed, unless the first end condition that the second end condition is satisfied is established at time t ₃₂ if, to change the release degree of the lock-up clutch 20 to the first release degree greater than that from the second release degree at time t ₃₂ ~t _33, it shifts the first start transition control of the 1LUC control.

  During the second slip control, the lockup clutch 20 is in the slip engagement state, so that the vibration of the power transmission system does not substantially occur. For this reason, it is good also as what does not transfer to 2nd slip control from 1st slip control.

[2. flowchart〕
Next, a control procedure performed by the CVTECU 8 will be described with reference to the flowcharts of FIGS. This flowchart starts (starts) when the first precondition and the second precondition are satisfied. This flow is repeatedly performed at a predetermined control cycle. Further, each step in the flowchart is performed by each function assigned to the hardware of the CVT ECU 8 being operated by software (computer program).

The flag F ₁ in the flowchart described below is set to “1” when the initial value is set to “0” and the first start condition (including vibration determination) is satisfied, and when the first end condition is satisfied. This flag is “0”. The flag F ₂ is a flag that is set to “1” when the initial value is set to “0” and the second start condition is satisfied, and is “0” when the second end condition is satisfied.
The flag F ₁₁ is a flag corresponding to each control in the first LUC control. The flag F ₁₁ is set to “1” as an initial value, and “1” is maintained when the first start transition control is performed, and “2” is maintained when the first slip control is performed. When the first end transition control is being performed, “3” is maintained. Similarly, the flag F ₂₁ is a flag corresponding to each control in the second LUC control. When the initial value is set to “1” and the second start transition control is performed, “1” is maintained, and when the second slip control is performed, “2” is maintained and the second end transition control is performed. If “3” is implemented, “3” is maintained.
Note that “(n)” appended to the flag F means a control cycle. For example, “(n−1)” means the previous control cycle, “(n)” means the current control cycle, and “(n + 1)” means the next control cycle.

As shown in FIG. 6, in steps S1 to S7, a start condition and an end condition are determined, and flags F ₁ and F ₂ are set.
In step S1, it is determined whether the first start condition is satisfied. If the first start condition is satisfied, the process proceeds to step S2, and if the first start condition is not satisfied, the process proceeds to step S4. As shown in (D2) above, if the first start condition is not satisfied, the first end condition is satisfied.
In step S2, the flag F ₁ of the current control cycle is set to “1”. Then, the process proceeds to step S3.

In step S3, it is determined whether or not the first end condition is satisfied. The process proceeds to step S3 after it is determined that the first start condition is satisfied. However, as shown in (D3) above, the speed ratio when the first start condition is satisfied fluctuates by a predetermined amount or more. For example, the first end condition is established in preference to the establishment of the first start condition. If the first end condition is satisfied, the process proceeds to step S4. If the first end condition is not satisfied, the process proceeds to step S7.
In step S4, the flag F ₁ of the current control cycle is set to “0”. Then, the process proceeds to step S5.

In step S5, it is determined whether the second start condition is satisfied. If the second start condition is satisfied, the process proceeds to step S6. If the second start condition is not satisfied, the process proceeds to step S7. As shown in (E2) above, if the second start condition is not satisfied, the second end condition is satisfied.
In step S6, the flag F ₂ of the current control cycle is set to “1”. Then, the process proceeds to step S10.
In step S7, it sets the flag F ₂ of the current control cycle to "0". Then, the process proceeds to step S10. For example, when the first start condition is satisfied and the first end condition is not satisfied, the process proceeds to step S7 without determining the second start condition or the second end condition. This is because, as shown in the above (C2) and (E2), when the first start condition is satisfied, the second end condition is satisfied at the same time as the second start condition is not satisfied.

Next, each flag F is referred to in steps S10 to S20.
In step S10, it is determined whether or not the flag F ₁ in the previous control cycle is “1”. If the flag F ₁ is “1”, the process proceeds to step S11. If not (if the flag F ₁ is “0”), the process proceeds to step S16.
In step S11, it determines a flag F ₁ in the present control cycle is "1" or not. If the flag F ₁ is “1”, the process proceeds to step S12. Otherwise (if the flag F ₁ is “0”), the process proceeds to step S14.

In step S12, determines a flag F ₁₁ in the present control cycle is "1" or not. The flag F ₁₁ is shifted to step S30 if it is "1", the process proceeds to step S13 otherwise.
In step S30, a first start transition control subroutine shown in FIG. 7 is executed.

In step S32 in FIG. 7, to reduce the engagement pressure P _LU stepwise. Then, control goes to a step S34.
In step S34, it decreases the engagement pressure P _LU gradually in the first release degree. And it returns to this control (returns), and transfers to step S36 of FIG.

In step S36, it is determined whether or not the differential rotation of the torque converter 2 is equal to or greater than the first differential rotation α. If this differential rotation is greater than or equal to the first differential rotation α, the process proceeds to step S38, and if it is less than the first differential rotation α, this control cycle ends (end).
At step S38, the both flag F ₁₁ and the flag F ₂₁ used in the next control cycle is set to "2". Then, this control cycle ends (end).

In step S13, the flag F ₁₁ in the present control cycle whether "2" is determined. If this flag F ₁₁ is “2”, the process proceeds to step S40, and if not, the process proceeds to step S50.
In step S40, a first slip control subroutine shown in FIG. 8 is executed.

  In step S42 of FIG. 8, it is determined whether or not the power transmission system is vibrating. In this step S42, it is determined whether or not the first drive slip control is completed, and it is determined whether or not the vibration of the power transmission system is in the second predetermined rotation speed change region. The second predetermined rotation speed change region is set to be smaller than the first predetermined rotation speed change region according to the first start condition determined in step S1, so that an affirmative determination is made in step S42. The first start condition is not necessarily satisfied (the first end condition is not satisfied).

At step S44, the differential rotation of the torque converter 2 performs feedback control for example by increasing the engagement pressure P _LU so that the second differential rotation beta (or less). This step S44 corresponds to the first drive slip control. And it returns to this control and complete | finishes this control cycle.
In step S46, the differential rotation of the torque converter 2 performs feedback control for example by increasing the engagement pressure P _LU so that the third differential rotation gamma (hereinafter). This step S46 corresponds to the first micro slip control. And it returns to this control and complete | finishes this control cycle.

In step S14, it is determined whether or not the flag F ₂ in the current control cycle is “1”. If the flag F ₂ is “1”, the process proceeds to step S15; otherwise (if the flag F ₂ is “0”), the process proceeds to step S18.
In step S15, both the flag F ₁₁ and the flag F ₂₁ used in the next control cycle is set to "3". Then, the process proceeds to step S50.
In step S50, a subroutine of end transition control (first end transition control, second end transition control) is executed. In this subroutine, the lock-up clutch 20 is shifted to the engaged state by increasing the engagement pressure P _LU in a ramp shape. Then, the process proceeds to step S52.

In step S52, it is determined whether or not the differential rotation of the torque converter 2 is absent or substantially absent (≈0). If there is no or almost no differential rotation, the process proceeds to step S54, and if not (if there is differential rotation), this control cycle is terminated.
In step S54, both the flag F ₁₁ and the flag F ₂₁ used in the next control cycle is set to "1". Then, this control cycle ends.

In step S16, it is determined whether or not the flag F ₂ in the previous control cycle is “1”. If the flag F ₂ is “1”, the process proceeds to step S17. Otherwise (if the flag F ₂ is “0”), this control cycle is terminated.
In step S17, as in step S14, it is determined whether or not the flag F ₂ in the current control cycle is “1”. If the flag F ₂ is “1”, the process proceeds to step S18. If not (if the flag F ₂ is “0”), the process proceeds to step S20.

At step S18, it determines a flag F ₂₁ in the present control cycle is "1" or not. If the flag F ₂₁ is “1”, the process proceeds to step S60, and if not, the process proceeds to step S19.
In step S60, the second start transition control subroutine shown in FIG. 9 is executed.

In step S62 in FIG. 9, to reduce the engagement pressure P _LU stepwise. Then, the process proceeds to step S64.
In step S64, it decreases the engagement pressure P _LU gradually in the second release degree. And it returns to this control (returns), and transfers to step S66 of FIG.

In step S66, it is determined whether or not the differential rotation of the torque converter 2 is equal to or greater than the first differential rotation α ′. If this differential rotation is greater than or equal to the first differential rotation α ′, the process proceeds to step S68, and if it is less than the first differential rotation α ′, this control cycle is ended.
In step S68, both the flag F ₁₁ and the flag F ₂₁ used in the next control cycle is set to "2". Then, this control cycle ends (end).

In step S19, the flag F ₂₁ in the present control cycle whether "2" is determined. This If the flag F ₂₁ is "2", the process proceeds to step S70, the process proceeds to step S50 otherwise.
At step S70, the difference rotation of the torque converter 2 performs feedback control for example by increasing the engagement pressure P _LU so that the second differential rotation beta '. Then, this control cycle ends.

In step S20, similarly to step S11, it determines a flag F ₁ in the present control cycle is "1" or not. If the flag F ₁ is “1”, the process proceeds to step S12. If not (if the flag F ₁ is “0”), the process proceeds to step S50.

For example, during the second start transition control, when the second end condition is satisfied and the first end condition is not satisfied (for example, when the vibration is determined and the first start condition is satisfied), the result is negative in step S66. Exit the determined by the control period, in the next control cycle, the affirmative determination is made in step S1 flag F ₁ in the current control cycle in step S2 is set to "1", step S7 is negative determination in step S3 Thus, the flag F ₂ is set to “0”. Then, a negative determination is made in step S10, an affirmative determination is made in step S16, a negative determination is made in step S17, an affirmative determination is made in step S20, an affirmative determination is made in step S12, and the process proceeds to the first start transition control in step S30. In the first start transition control at this time in the second start transition control that was performed before engagement pressure P _LU because it is reduced in steps, the process proceeds to step S34 by omitting the step S32. In this manner, when vibration of the power transmission system is determined by the vibration determination means 8c while the lockup clutch 20 is shifted to the first slip engagement state with the second release degree, the second release is performed. The degree is changed to the first release degree, and the lockup clutch 20 is gradually shifted to the first slip engagement state.

Conversely, if the first end condition is satisfied but the second end condition is not satisfied (when the second start condition is satisfied) during the execution of the first start transition control, a negative determination is made in step S36. Exit control period Te, in the next control cycle, the determination is negative in step S1 flag F ₁ in the current control cycle in step S4 is set to "0", this time at step S6 is affirmative determination in step S5 The control cycle flag F ₂ is set to “1”. Then, an affirmative determination is made in step S10, a negative determination is made in step S11, an affirmative determination is made in step S14, an affirmative determination is made in step S18, and the process proceeds to the second start transition control in step S60. Second start transition control at the time this is also the first start transition control that was performed before engagement pressure P _LU because it is reduced in steps, the process proceeds to step S64 by omitting the step S62. In this way, the first release degree is changed to the second release degree, and the lockup clutch 20 is gradually shifted to the first slip engagement state.

If the first end condition is satisfied and the second start condition is satisfied while the first slip control is being performed, a negative determination is made in step S1, and the flag F ₁ of the current control cycle is set to “ It is set to 0 ", and an affirmative determination is made in step S5 the flag F ₂ of the current control cycle in step S6 is set to" 1 ". Then, an affirmative determination is made in step S10, a negative determination is made in step S11, an affirmative determination is made in step S14, a negative determination is made in step S18, an affirmative determination is made in step S19, and the process proceeds to the second slip control in step S70. In this case, while suppressing the sudden change in engagement pressure P _LU lamp control, it is preferable to shift to the second slip control.
Note that the second slip control is control for preventing vibration when vibration is not generated, and it cannot be assumed that vibration occurs during the execution of the control. Therefore, it cannot be assumed that the second end condition is satisfied and the second start condition is satisfied during the execution of the second slip control.

[3. Action and effect)
Since the control device for an automatic transmission according to an embodiment of the present invention is configured as described above, the following operations and effects can be obtained.
When the CVT ECU 8 determines that there is vibration of the power transmission system by the vibration determination unit 8c, the CVT ECU 8 performs the first start transition control for shifting the lockup clutch 20 to the first slip engagement state. Vibration can be reliably absorbed in the lock-up clutch 20 that functions as a damper. Thereby, the vibration of the power transmission system can be quickly suppressed.

After the first start transition control, the CVT ECU 8 shifts the lock-up clutch 20 in the first slip engagement state to the second slip engagement state in which the slip amount is smaller than that in the first slip engagement state. Since slip control is performed, vibration of the power transmission system can be absorbed while suppressing a decrease in power transmission efficiency.
When the vibration determination unit 8c does not determine the vibration of the power transmission system, that is, when it is determined that the differential rotation of the torque converter 2 is stable, the CVTECU 8 switches the lock-up clutch 20 in the second slip engagement state to the first. In order to implement the first micro slip control that shifts to the third slip engagement state in which the slip amount is further smaller than the slip engagement state of 2, the deterioration of the power transmission efficiency is suppressed and the facing of the lockup clutch 20 is deteriorated. It can also be suppressed, and further contributes to reliably suppressing vibration of the power transmission system.

  As described above, the CVTECU 8 performs the first LUC control for gradually reducing the slip amount of the lockup clutch 20 in the order of the first, second, and third slip engagement states. As a result, it is possible to suppress a decrease in drivability due to a decrease in direct feeling and to absorb vibrations of the power transmission system with certainty.

  The vibration absorption of the power transmission system by the first LUC control for shifting the lockup clutch 20 to the first to third slip engagement states is as shown in (B2) above when the lockup clutch 20 is in the engagement state. It is set as a state in which the vibration of the power transmission system can be generated in advance, and the fact that the vehicle is in the region B is implemented as the start condition of the first LUC control, so that the vibration of the power transmission system can be appropriately suppressed.

  As shown in the above (B2) and (D2), the first end condition includes that the region B is not in the traveling state of the vehicle, so that the traveling state of the vehicle is in the region where the vibration of the power transmission system is unlikely to occur. In some cases, the first LUC control and the second LUC control are not performed, and it is possible to prevent an unnecessary decrease in power transmission efficiency and a decrease in durability due to wear of the facing of the lockup clutch 20.

  For example, if the region B covers most of the travel conditions that the vehicle can take, the first end condition is unlikely to be satisfied if the travel state of the vehicle deviates from the region B, but the speed change is performed as in (D3) above. By adding the requirement of the amount of change in the ratio, frequent occurrence of the first LUC control can be suppressed, and a decrease in durability of the lockup clutch 20 and a decrease in power transmission efficiency can be suppressed. Therefore, the vibration of the power transmission system can be appropriately suppressed.

  As shown in the above (B1), (C1), and (C2), the second start condition of the second LUC control includes that the traveling state of the vehicle is the region A, but that there is vibration of the power transmission system. Not a requirement. For this reason, even if the vibration of the power transmission system does not occur, the second LUC control in which the lockup clutch 20 is slip-engaged in the region A where the vibration of the power transmission system is more likely to occur than in the region B. The vibration of the transmission system can be prevented beforehand.

  In the first start transition control of the first LUC control, the lockup clutch 20 is smoothly shifted to the slip engagement state in order to gradually shift the lockup clutch 20 to the first slip engagement state with the first release degree. This contributes to ensuring the durability and drivability of the lock-up clutch 20.

Since the first release degree is larger than the second release degree in the second start transition control of the second LUC control, the vibration of the power transmission system can be quickly suppressed.
On the other hand, in the second start transition control of the second LUC control, the lockup clutch 20 is gradually brought into the first slip engagement state with a second release degree smaller than the first release degree. At this time, since it is not determined that there is vibration of the power transmission system, priority is given to smooth transition of the lock-up clutch 20 to the slip engagement state, and a decrease in drivability can be further suppressed.

  When the second start transition control of the second LUC control is performed, the CVTECU 8 sets the release degree of the lockup clutch 20 to the second release if the second end condition is satisfied but the first end condition is not satisfied. In order to change from the degree to the first release degree larger than this and shift to the first start transition control of the first LUC control, the vibration of the power transmission system during the execution of the first LUC control that does not require the vibration of the power transmission system. Even if this occurs, the vibration can be quickly suppressed.

If it is added to the first precondition that the accelerator opening (A5) is equal to or greater than a predetermined opening, the fuel consumption can be suppressed and the facing durability of the lockup clutch 20 can be ensured.
Further, in the first precondition, the difference rotation between the input side rotation and the output side rotation of the auxiliary transmission mechanism (A6) described above is less than a predetermined rotational speed, and the auxiliary transmission mechanism is not shifting (replacement). If this is added, it is possible to prohibit the first LUC control while changing the gear ratio, that is, when the natural resonance frequency is changing, and to avoid unnecessary execution of the first LUC control.

If it is added to the first start condition that the detected vibration frequency of (B3) is within a predetermined frequency range from the natural resonance frequency corresponding to the gear ratio at the time of detection, it is caused by the natural resonance frequency of the power transmission system. Therefore, when the power transmission system is not oscillating, unnecessary execution of the first LUC control can be prevented.
Thus, by suppressing the implementation of the unnecessary first LUC control, fuel efficiency can be improved, and durability of the lockup clutch 20 can be ensured.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Each structure of one Embodiment mentioned above can be selected as needed, and may be combined suitably.
In the above-described embodiment, the region B within the predetermined gear ratio range in the region B is the region A, but the region within the predetermined turbine rotation speed range in which vibration is more likely to occur may be the region A. .
In the second drive slip control of the second LCU control, the control corresponding to the first micro slip control has been described. However, in the second LUC control, the second drive slip control is the same as the first micro slip control after the second drive slip control. Second micro slip control may be performed. Thus, the second LCU control may be the same control as the first LCU control.

Further, although the first LCU control is described as being performed with priority over the second LCU control, conversely, the second LCU control may be performed with priority over the first LCU control. For example, if the traveling state of the vehicle is in the region A, the second LCU control may be performed, and the first LCU control may not be performed even if the vibration of the power transmission system is detected. Further, the vibration of the power transmission system is determined only when the vehicle running state is not in the region A but in the region B. When the vehicle B is in the region B and the vibration is determined, the first LCU control is performed. It is good also as a structure to implement.
In addition, the description has been given of the transition to the second LUC control or the first LUC control in the middle of the first LUC control or the second LUC control. Alternatively, after the entire control (start transition control, slip control, end transition control) of the first LUC control or the second LUC control is performed, the process may proceed to the second LUC control or the first LUC control. In this case, although there is a possibility that vibration absorption of the power transmission system may not be performed quickly, the control algorithm can be simplified.

Further, although the first release degree of the first start transition control has been described as being greater than the second release degree of the second start transition control, it may be set smaller than or equal to the second release degree. May be. In this case, since the engagement pressure P _LU in the first start transition control varies more smoothly, thereby improving the drivability.

In the first LUC control or the second LUC control, any or all of the first start transition control, the second start transition control, the first end transition control, and the second end transition control may be omitted. In this case, although the drivability is lowered, the control algorithm can be simplified.
Further, at least the first LUC control may be performed. That is, the second LUC control may be omitted. In this case, although the vibration of the power transmission system cannot be prevented in advance, the control algorithm can be simplified.

Furthermore, (B2) may not be a requirement for the first start condition. As shown in the above (B1), if the vibration of the power transmission system is determined, the first LUC control is performed regardless of the traveling state of the vehicle. In this case, the first LUC control may be frequently performed, but the vibration of the power transmission system can be reliably suppressed.
Further, as described above, the sub-transmission mechanism may be provided in the power transmission system of the vehicle, and the location of the sub-transmission mechanism is not limited to the upstream side in the power transmission direction of the transmission. It may be downstream in the transmission direction.

1 engine (motor)
DESCRIPTION OF SYMBOLS 11 Engine output shaft 2 Torque converter 20 Lockup clutch 21 Torque converter output shaft 22 Converter housing 23 Pump impeller 24 Turbine runner 25 One-way clutch 26 Stator 3 Forward / reverse switching mechanism 30 Double pinion planetary gear 31 Forward clutch 32 Reverse brake 4 Belt type Continuously variable transmission mechanism (variator)
40 transmission mechanism input shaft 41 transmission mechanism output shaft 42 primary pulley 42a fixed pulley 42b slide pulley 43 secondary pulley 43a fixed pulley 43b slide pulley 44 belt 45 primary pressure chamber 46 secondary pressure chamber 5 final reduction mechanism 50 idler shaft 51 drive shaft 52 first 1 gear 53 2nd gear 54 3rd gear 55 final reduction gear 56 differential gear 6 drive wheel 7 hydraulic control unit 70 oil pump 71 hydraulic control circuit 72 line pressure solenoid 73 primary pressure solenoid 74 secondary pressure solenoid 75 forward clutch pressure solenoid 76 reverse Brake pressure solenoid 77 Lock-up solenoid 78 Lock-up control valve 8 CVT electronic control unit (CVTECU, control device, variable Ratio detection means)
8A Prerequisite condition determination unit 8B Start condition determination unit 8c Vibration determination unit (vibration determination means)
8d Traveling state determination unit (traveling state determination means)
8E 1st LUC control unit 8F 2nd LUC control unit 8G End condition determination unit 80 Line pressure sensor 81 Primary pressure sensor 82 Secondary pressure sensor 83 Engine rotation speed sensor 84 Primary rotation speed sensor (running state detection section)
85 Secondary rotational speed sensor (running state detector)
86 Inhibitor switch (Inhibitor SW)
87 Accelerator opening sensor 88 Idle switch (Idle SW)
89 Brake switch 9 Engine ECU
84 Engine speed sensor 100 Belt type continuously variable transmission (automatic transmission)
r Gear ratio N Turbine speed P _LU engagement pressure P _LUS reference engagement pressure α First differential rotation β Second differential rotation γ Third differential rotation

Claims (7)

A lock-up clutch capable of achieving any of an engagement state, a release state, and a slip engagement state in a torque converter provided in a power transmission system between a prime mover that is a drive source of a vehicle and a drive wheel;
A rotational speed sensor for detecting the rotational speed of a rotary shaft provided in the power transmission system;
Vibration determining means for determining whether or not the rotation speed detected by the rotation speed sensor is vibrating;
Traveling state detecting means for detecting the traveling state of the vehicle;
Control means for controlling the lock-up clutch,
When the lockup clutch is in an engaged state, the control means is in a first running state set in advance as a state in which the running state detected by the running state detecting means is capable of generating the vibration. The lockup clutch is shifted to the first slip engagement state on the condition that the rotational speed is determined by the vibration determination means to start, and then the lockup clutch is moved to the first slip engagement. When the state is shifted to the second slip engagement state where the slip amount is smaller than the state, and the vibration determination means determines that the rotational speed is not oscillating in the second slip engagement state, the lockup clutch is The control of the automatic transmission that performs the first control to shift to the third slip engagement state with a smaller slip amount than the second slip engagement state. Apparatus. The control means performs end transition control for shifting the lockup clutch from the slip engagement state to the engagement state on the condition that the travel state detected by the travel state detection means is not the first travel state. The control device for an automatic transmission according to claim 1 to be implemented. A gear ratio detecting means for detecting the gear ratio is provided,
The control means sets the lockup clutch from the slip engagement state on the condition that the speed ratio detected by the speed ratio detecting means fluctuates to a predetermined amount or more when the start condition is satisfied. The control device for an automatic transmission according to claim 1 or 2, wherein end transition control for shifting to the engaged state is performed. The control means determines that the number of rotations is not oscillating by the vibration determination means, and the traveling state detected by the traveling state detection means further generates the vibration in the first traveling state. The lockup clutch is shifted to the first slip engagement state on the condition that the second running state is set in advance as the easy state, and then the lockup clutch is moved to the first slip engagement state. The control device for an automatic transmission according to any one of claims 1 to 3, wherein a second control is performed to shift to a second slip engagement state in which a slip amount is smaller than a state. When the start condition is satisfied in the first control, the control means shifts the lock-up clutch to the first slip engagement state at a preset first release degree. The control device for an automatic transmission according to any one of claims 1 to 4, wherein the control is performed. The control means shifts the lock-up clutch to the first slip engagement state with a second release degree smaller than the first release degree when the start condition is satisfied in the second control. The control device for an automatic transmission according to claim 5, wherein the second start transition control is performed. In the second start transition control, the control means causes the vibration determination means to vibrate the rotational speed during the transition of the lockup clutch to the first slip engagement state at the second release degree. When the start condition for the first control is satisfied and the second release degree is changed to the first release degree, the lockup clutch is shifted to the first slip engagement state. The control apparatus for an automatic transmission according to claim 6, wherein the control is shifted to first start transition control.

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