JP4590806B2 - Automatic transmission lockup control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lockup control device for an automatic transmission capable of setting an engagement start pressure in a form adapted to a control state of a lockup clutch when a lockup clutch is engaged from a standby pressure state. .
[0002]
[Prior art]
FIG. 11 is a time chart showing the relationship between the change in the lockup pressure of the lockup clutch during the speed change operation, the engine speed and the transmission input speed.
[0003]
The lock-up clutch can be engaged in (1) when the lock-up clutch is completely engaged from the OFF state through the standby pressure state after the servo activation control, and (2) up-shift as shown in FIG. During shift control such as shifting or downshifting, there is a case where the lock-up clutch is temporarily released and slid to temporarily re-engage in order to alleviate shift shock. Conventionally, in any case, the rising hydraulic pressure at the time of complete engagement, that is, the complete engagement start pressure P_LONSt_1 was uniquely determined according to the input torque from the engine regardless of the control mode of the lockup clutch.
[0004]
[Problems to be solved by the invention]
However, the full engagement start pressure P_LONWhen St_1 is determined according to the input torque from the engine, the differential pressure of the lockup clutch immediately before the full engagement start pressure is applied, that is, the standby pressure P of the lockup clutch._UPWAITAnd the slip amount (difference between engine speed Engine Rev. and transmission input speed Input Rev. in FIG. 10) is different._LONThere is an inconvenience that it becomes difficult to set the engagement feeling after the supply of St_1 and the time until the engagement is completed according to each situation.
[0005]
    In view of the above circumstances, the present invention provides a lockup control device for an automatic transmission capable of setting an engagement start pressure such as a complete engagement start pressure in a form adapted to the control state of a lockup clutch. It is for the purpose.
[Means for Solving the Problems]
    The invention of claim 1 provides a lock-up pressure (P_LUP) In the lockup control device for an automatic transmission that can control the engagement state of the lockup clutch (5) of the torque converter (1).The control for engaging the lockup clutch from the disengaged state and the control for engaging from the temporarily disengaged state accompanying the shift operation of the automatic transmission are divided.A control mode recognition determination unit (53) for determining and recognizing is provided, and the lockup clutch is placed in a standby pressure state (P_WAIT) From the engagement start pressure (P_LONEngagement start pressure calculating means (53, step S4 of the lockup clutch control program RCP, etc.) for calculating St_i) is provided, and the engagement according to the control mode of the lockup clutch calculated by the engagement start pressure calculating means is provided. Engagement execution means (53, step S4 to step S8 of the lockup clutch control program RCP, etc.) for starting the engagement operation of the lockup clutch from the standby pressure state based on the combined start pressure is provided. .
[0007]
    Claim2The invention of claim1In the invention, the control mode recognition determining means recognizes and determines the temporary opening control accompanying the shift operation of the automatic transmission separately for the control accompanying the downshift and the control accompanying the upshift. Composed.
[0008]
    Claim3In the invention of the present invention, the engagement start pressure calculating means includes an engagement start pressure P_LONSt_i
      P_LONSt_i = Ai · f (trg) + Bi
      Ai: a predetermined gain based on the control mode of the lockup clutch
      f (trg): value obtained as a function of engine torque trg
      Bi: It is characterized in that it is obtained by calculation with a predetermined pressure value based on the control mode of the lockup clutch.
[0009]
    Claim4The invention of claim3In the invention, the engagement start pressure calculating means makes Ai constant, and changes Bi according to the engine torque, whereby the engagement start pressure P_LONIt is characterized by calculating St_i.
[0010]
    Claim5The invention of claim3In the invention, the engagement start pressure calculating means sets Ai constant, and changes Bi according to the difference between the engine speed and the input speed of the automatic transmission, whereby the engagement start pressure P_LONIt is characterized by calculating St_i.
[0011]
    Claim6The invention of claim3In the invention, the engagement start pressure calculating means makes Bi constant, and changes Ai according to the engine torque, whereby the engagement start pressure P_LONIt is characterized by calculating St_i.
[0012]
    Claim7The invention of claim3In the invention, the engagement start pressure calculating means makes Bi constant, and changes Ai according to the difference between the engine speed and the input speed of the automatic transmission, whereby the engagement start pressure P_LONIt is characterized by calculating St_i.
[0013]
【The invention's effect】
    According to the invention of claim 1, the control mode recognition determining means (53) recognizes and determines the control mode of the lockup clutch, and the engagement start pressure calculating means (53, step S4 of the lockup clutch control program RCP, etc.). By the control mode recognition determination meansThe control for engaging the lockup clutch from the open state and the control for engaging from the temporary open state accompanying the shift operation of the automatic transmission are divided intoBased on the control mode of the lockup clutch determined to be recognized, the lockup clutch is set to the standby pressure (P_WAIT) Engagement start pressure (P) when engaging from the state (including the case of complete engagement and the transition to slip control in the subsequent control)_LONSt_i) is calculated, and the engagement execution means (53, step S4 to step S8 of the lockup clutch control program RCP, etc.) waits based on the engagement start pressure corresponding to the calculated control mode of the lockup clutch. Since the engagement operation of the lockup clutch is started from the pressure state,The engagement start pressure (P _LON St_i)The engagement start pressure can be set(P_LONSt_i)It is possible to easily set the engagement feeling and the time until the engagement is completed after the supply is made in accordance with each situation.
[0015]
    Claim2According to the invention of the present invention, the control for completely engaging the temporarily disengaged state associated with the shifting operation of the automatic transmission is recognized and determined separately for the control associated with the downshift and the control associated with the upshift. Detailed control is possible.
[0016]
    Claim3According to the invention, the change in the control mode of the lockup clutch can be calculated in a form reflecting the gain Ai or the pressure value Bi, and the parameters can be simplified.
[0017]
    Claim4According to the invention, it is not necessary to change the gain Ai, and the engagement start pressure P can be obtained only by the engine torque._LONSt_i can be determined, it can be easily handled even if the engine changes, and it is highly versatile.
[0018]
    Claim5According to the invention, it is not necessary to change the gain Ai, and the engagement start pressure P is determined according to the difference between the engine speed and the input speed of the automatic transmission._LONSt_i can be determined, it can be easily handled even if the engine changes, and it is highly versatile.
[0019]
    Claim6According to the invention, the engagement start pressure P is obtained by making the pressure value Bi constant and changing the gain Ai according to the engine torque._LONSt_i can be calculated.
[0020]
    Claim7According to the invention, the engagement start pressure P is obtained by keeping the pressure value Bi constant and changing the gain Ai according to the difference between the engine speed and the input speed of the automatic transmission._LONSt_i can be calculated.
[0021]
Note that the numbers in parentheses are for the sake of convenience indicating the corresponding elements in the drawings, and therefore the present description is not limited to the descriptions on the drawings.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
1 is a cross-sectional view illustrating an example of a torque converter, FIG. 2 is a diagram illustrating an example of a hydraulic circuit of the torque converter, FIG. 3 is a control block diagram illustrating an example of a lockup control device for an automatic transmission, and FIG. Is a flowchart showing an example of a lockup clutch control program, FIG. 5 is a flowchart showing an example of an upshift engagement program, FIG. 6 is a flowchart showing an example of a downshift engagement program, and FIG. 7 is related to a lockup operation. FIG. 8 is a time chart showing the relationship between the change in lock-up pressure of the lock-up clutch and the engine speed and transmission input speed. FIG. 8 shows the change in the lock-up pressure of the lock-up clutch during the upshift operation and the engine speed. FIG. 9 is a time chart showing the relationship between the transmission speed and the transmission input rotational speed. 10 is a time chart showing the relationship between the change in the lockup pressure of the lockup clutch, the engine speed and the transmission input speed, and FIG. 10 is a diagram showing various modes when setting the complete engagement start pressure. is there.
[0023]
As shown in FIG. 3, a torque converter 1 is connected to the vehicle engine 50, and an automatic transmission 51 is connected to the torque converter 1. As a result, the rotation of the engine 20 is input to the automatic transmission 51 via the torque converter 1, where an appropriate speed change operation is performed and transmitted to an axle (not shown).
[0024]
An engine control unit 52 is connected to the engine 50, a torque converter control unit 53 is connected to the torque converter 1, and a transmission control unit 55 is connected to the automatic transmission 51.
[0025]
As shown in detail in FIG. 1, the torque converter 1 has a converter housing 2 including a front cover 2 a as an input element and a case 2 b that are fixed to a drive plate and to which rotation from the engine 50 is input. In the housing, the pump impeller 1a provided integrally with the case 2b, the turbine impeller 1b connected to the input shaft 23 of the automatic transmission 51 and integrally connected to the turbine hub 3 serving as an output element, and the one-way A stator impeller 1c that is prevented from rotating in one direction by the clutch 4 is housed, and a torus is formed by these impellers. A lock-up clutch 5 is disposed between the torus and the front cover 2a. The clutch 5 includes a clutch plate 6 and a damper 22 including two types of springs 22a and 22b. When the friction material 6a fixed to the clutch plate 6 contacts the front cover 2a, the rotation of the crankshaft of the engine E is directly transmitted to the turbine hub 3 via the front cover 2a, the clutch plate 6 and the damper 22. It is transmitted to the input shaft 23 of the automatic transmission 51 that is splined to the hub 3. In addition, the clutch plate 6 forms a first oil chamber 9 that acts on the clutch cover on the off side with the front cover 2a, and on the back side, that is, on the torus side, the clutch plate acts on the on side. Two oil chambers 10 are formed, and are engaged and released by a pressure difference (lock-up pressure) between the two oil chambers 9 and 10 as will be described later.
[0026]
Next, a hydraulic control circuit for the lockup clutch 5 in the torque converter 1 will be described with reference to FIG.
[0027]
The hydraulic control circuit includes a lockup control valve 21, a lockup relay valve 35, a linear solenoid valve 19, and a solenoid valve 36.
[0028]
The lockup relay valve 35 has a spool 35a, a control oil chamber 36a is formed at the upper end of the spool, and an oil chamber 37b in which the line pressure PL from the line pressure oil passage 37 acts on the lower end of the spool. Is formed. Further, the valve 35 includes a supply port 11d communicating with the secondary pressure oil passage 11, a third port 12c communicating with the pressure regulating oil passage 12, and a lubricating oil pressure PJ from a secondary regulator valve (not shown). A port 39a communicating with the oil passage 39 to which the gas is supplied, a first port 9d communicating with the first oil chamber 9 of the torque converter 1, and a first port communicating with the second oil chamber 10. 2 port 10c, a fourth port 21a communicating with a discharge oil passage led to a cooler or the like, and a plurality of drain ports EX. Further, a fifth port 37a communicating with the line pressure oil passage 37 and a sixth port communicating with the supply port 40a of the linear solenoid valve 19 via the oil passage 40 are connected to the lower end portion of the relay valve 35. 40b is formed. The oil passage 11 on which the secondary pressure PS acts and the line pressure oil passage 37 communicate with each other via a check valve 41.
[0029]
The lock-up control valve 21 has a first spool 21a and a second spool 21b. The upper end of the first spool communicates with the first oil chamber 9 of the torque converter via an oil passage 9b. The off-side oil chamber 9a is formed, and the control pressure oil passage 42 is formed in the middle stage of the first spool so as to act in the same direction as the oil chamber 9a.₁A control oil chamber 42a is formed in communication with the control oil chamber 42a. A spring 21c is contracted at the lower end of the second spool 21b, and an on-side oil chamber 10a communicating with the second oil chamber 10 of the torque converter via oil passages 10d and 10b is formed. ing. Further, the valve 21 is formed with a pressure adjusting port 12a communicating with the pressure adjusting oil passage 12, and a supply port 11a and a drain port communicating with the secondary pressure oil passage 11 adjacent to the port 12a. EX is formed.
[0030]
The lock-up differential pressure control solenoid valve 19 comprising a linear solenoid valve has a supply port 40a to which line pressure is supplied via the oil passage 40, a control pressure port 42b, a drain port EX and a release port 19a. Based on a predetermined electrical signal from the controller, the hydraulic pressure of the supply port 40a is adjusted and output from the control pressure port 42b.
[0031]
The solenoid relay valve 43 has a spring at the upper end of the spool, a port 43a connected to the oil passage B1, and an oil chamber 43b at the lower end of the spool. An oil passage 42 is connected to the control pressure port 42b of the linear solenoid valve 19 for differential pressure control.₂ The control pressure oil passage 42 has a port 42d that communicates with each other via the port 42d.₁ And a port 43c communicating with a secondary port of a primary regulator valve (not shown).
[0032]
The solenoid valve 36 switches the hydraulic pressure of the control port 36b between a supply state and a drain state based on an electric signal (ON, OFF) from the control unit. The port 36 b communicates with an oil passage 36 c that communicates with the oil passage B 2 via the orifice 45, and the oil passage 36 c communicates with the control oil chamber 36 a of the lockup relay valve 35. The line pressure is supplied to the oil passage B2 at the second, third and fourth speeds, and the line pressure is supplied to the oil passage B1 at the second speed in the second range and the first range.
[0033]
Next, the operation of this embodiment will be described. In the first speed state, based on the electrical signal from the torque converter control unit 53, the solenoid valve 36 is in the drain state, and the lockup relay valve 35 is based on the fact that no hydraulic pressure is acting on the control oil chamber 35a. , In the OFF position (left half position in FIG. 5). The solenoid relay valve 43 does not act on the control chamber 43b and is in the right half position in FIG. 5, and the lockup clutch control pressure oil passage 421 is in a drain state (communication between the port 42c and the drain port EX). Therefore, the lock-up control valve 21 is in the right half position without hydraulic pressure acting on the control oil chamber 42a. When the lock-up relay valve 35 is in the OFF position, the port 37a is shut off and the port 40b communicates with the drain port EX. Therefore, the supply port 40a of the linear solenoid valve 19 is in the drain state.
[0034]
The secondary (converter) hydraulic pressure is supplied from the oil passage 11 to the first oil chamber 9 of the torque converter 1 through the ports 11d and 9d of the relay valve 35 and the oil passage 9c, while the oil in the second oil chamber 10 is oil. It is led to the cooler communication pipe 46 and the cooler bypass valve 47 through the passage 10 b, the ports 10 c and 21 a of the relay valve 35 and the oil passage 21. Therefore, the lock-up clutch 5 is in the released state, and the rotation of the engine crankshaft is transmitted to the turbine hub 3 exclusively through the oil flow acting on the pump impeller 1a, stator impeller 1c and turbine impeller 1b, and It is transmitted to the input shaft 23 of the automatic transmission 51. The released state of the lock-up clutch 5 is not limited to the switching of the solenoid relay valve 43 at the first speed, but appears even when the solenoid valve 36 and / or the linear solenoid valve 19 are off at the second, third, and fourth speeds. To do.
[0035]
Further, at the second speed in the D range, the solenoid relay valve 43 is switched to the left half position in FIG. 2 by supplying the line pressure to the control chamber 43b due to the supply of the line pressure to the oil passage B2. The input port 42d communicates with the lockup clutch control output port 42c. In this state, when the torque converter control unit 53 issues a lock-up clutch on signal to the solenoid valve 36 and the linear solenoid valve 19, first, the solenoid valve 36 is switched to the supply state, and the lock-up relay valve is set via the oil passage 36c. The line pressure is applied to the control oil chamber 36a of 35, and the relay valve 35 is switched to the ON position (the right half position in FIG. 5). In this state, the secondary (converter) hydraulic pressure PS from the oil passage 11 is supplied to the second oil chamber 10 of the torque converter 1 via the ports 11d and 10c of the relay valve 36 and the oil passage 10b, whereas the first The oil in the oil chamber 9 is guided to the pressure adjusting port 12a of the control valve 21 through the oil passage 9c, the ports 9d and 12c of the relay valve 35 and the pressure adjusting oil passage 12.
[0036]
Further, based on the switching to the ON position, the relay valve 35 communicates with the ports 37a and 40b, and the line pressure of the line pressure oil passage 37 is directly supplied to the supply port 40a of the linear solenoid valve 19 through the oil passage 40. Is done. A predetermined pressure regulation signal is output from the torque converter control unit 53 to the linear solenoid valve 19 substantially at the same time or slightly after the switching of the relay valve 35 to the ON position. Then, the linear solenoid valve 19 regulates the line pressure supplied to the supply port 40a and outputs it to the control pressure port 42b. The control oil pressure is supplied to the oil passage 422, the ports 42d and 42c of the solenoid valve 43, and the oil passage 42.₁ To the control oil chamber 42a of the lockup control valve 21.
[0037]
When the lock-up clutch 5 is completely engaged (ON), the lock-up differential pressure control linear solenoid valve 19 generates a relatively high control pressure, and accordingly, a high control pressure is applied to the control oil chamber 42a. Thus, the control valve 21 is held at the left half position in FIG. 5, and the pressure adjusting port 12a communicates with the drain port EX, and the hydraulic pressure from the oil passage 12 is discharged. In this state, in the lockup clutch 5, the friction material 6a of the clutch plate 6 comes into full contact with the front cover 2a based on the pressure difference between the first oil chamber 9 and the second oil chamber 10, and the clutch is engaged. The rotation of the engine crankshaft is transmitted to the turbine hub 3 via the lockup clutch 5.
[0038]
Further, during upshifting or downshifting of the automatic transmission, the torque converter control unit 53 issues a slip control signal to the differential pressure control linear solenoid valve 19 in order to prevent a shift shock from occurring. As a result, the valve 19 detects the input side (engine speed) and the output side speed (automatic transmission input speed) of the torque converter 1, and signals such that the differential speed becomes a target value, for example. And outputs a predetermined hydraulic pressure from the control pressure port 42b, and the hydraulic pressure acts on the control oil chamber 42a of the control valve 21 through the oil passages 422 and 421. In this state, the oil pressure in the first oil chamber 9 acts on the off-side oil chamber 9a at the upper end of the spool 21a in the control valve 21 via the oil passage 9b, and the oil pressure in the second oil chamber 10 is the oil pressure. Acting on the on-side oil chamber 10a at the lower end of the spool 21b via the passage 10b, the control valve 21 is in a state where the oil pressures of the oil chambers 9 and 10 are directly opposed to each other, and in the differential pressure acting state, Based on the hydraulic pressure in the control oil chamber 42a from the differential pressure control linear solenoid valve 19, the pressure adjusting port 12a changes the throttle amount ratio between the supply port 11a and the drain port EX, and adjusts the hydraulic pressure in the pressure adjusting port 12a. ·Change. As a result, a predetermined pressure is applied to the first oil chamber 9 against the secondary pressure PS of the second oil chamber 10, and the lock-up clutch 5 causes the friction material 6a of the clutch plate to slip into the front cover 2a. The slip control state in which the predetermined number of rotations is brought into contact is brought about.
[0039]
In this way, the engagement operation of the lockup clutch is performed, and in the engagement operation, the torque converter control unit 53 further performs the following control.
[0040]
That is, when the automatic transmission 51 is controlled by the transmission control unit 55 and an upshift or downshift operation is performed, the upshift signal UPS or the downshift signal DNS is transmitted from the transmission control unit 55 to the torque. Output to the converter control unit 53, the torque converter control unit 53 recognizes that the control to be performed from now on is temporary opening control accompanying the shift operation of the automatic transmission. When the torque converter control unit 53 determines to lock up the lockup clutch from the released state based on the engine speed signal from the engine control unit 52, the torque converter control unit 53 performs the control to be performed from now on. Recognizes that the control is associated with the lockup operation of the lockup clutch.
[0041]
Accordingly, when the torque converter control unit 53 recognizes the control to be performed from now on, the torque converter control unit 53 reads the corresponding control program from a memory (not shown), and performs the engagement control of the lockup clutch according to the read control program.
[0042]
That is, when it is determined that the control to be performed is a control associated with the lockup operation of the lockup clutch, the lockup clutch control program RCP shown in FIG. 4 is read and the control is performed based on the lockup clutch control program RCP. Control.
[0043]
The torque converter control unit 53 starts the timer t1 in step S1 of the lockup clutch control program RCP, enters step S2, and performs servo activation control. Then, the lockup pressure P, which is the differential pressure between the first oil chamber 9 and the second oil chamber 10 of the lockup clutch 5._LUPIs the initial pressure P at time T1 in FIG._FTo a predetermined standby pressure P after the lock-up clutch 5 has moved to the point of engagement._WAITCan be lowered. In step S3, when a predetermined time t1 = TimeServo has elapsed from the start of control in step S1, the lockup pressure P_LUPIs fully engaged starting pressure P_LONIt is increased to St_1 and then swept up with a gradient dPLON1, but this fully engaged starting pressure P_LONSt_1 and the gradient dPLON1 are changed according to the currently performed control, as shown in step S4 and step S5.
[0044]
That is, when the complete engagement start pressure is described, as shown in step S4, the control currently being performed is the control associated with the lock-up clutch lock-up operation, and therefore the lock-up clutch ON control from the released state. The fully engaged starting pressure is P_LONWhen the control is St_1 and the control is accompanied by the upshift operation of the automatic transmission, the complete engagement start pressure is P_LONWhen it is St_2 and the control is associated with the downshift operation of the automatic transmission, the complete engagement start pressure is P_LONSt_3.
[0045]
This complete engagement starting pressure P_LONSt_i (i = 1, 2, 3: The number i corresponds to the control mode of the lockup clutch, the number 1 is the control associated with the lockup operation of the lockup clutch, and 2 is the upshift shift of the automatic transmission. Temporary release control 3 associated with the operation corresponds to temporary release control 3 associated with the downshift operation of the automatic transmission._LONThe formula for St_i and the numbers of each subscript i shown in FIG. 10 have the same meaning), the torque converter control unit 53
P_LONSt_i = Ai · f (trg) + Bi
And the obtained engagement starting pressure P_LONBased on St_i, the hydraulic pressure of the lockup clutch 5 is controlled. That is, the engagement start pressure P_LONSt_i is obtained by multiplying a value f (trg) obtained as a function of the engine torque trg by a predetermined gain Ai based on the control mode and adding a predetermined pressure value Bi based on the control mode to the obtained pressure. .
[0046]
Further, the gain Ai and the pressure value Bi take various values depending on how the parameters are taken. Examples of such values are shown in (a) to (d) of FIG.
[0047]
FIG. 10A shows a case where the gain Ai is fixed for each control mode and the engine torque is adopted as a parameter for determining the pressure value Bi. FIG. 10B shows a case where the gain Ai is FIG. 10C shows a case where the slip speed, which is the difference between the engine speed and the input speed of the automatic transmission, is adopted as a parameter for determining the pressure value Bi when the control mode is fixed. FIG. 10D shows the case where the engine torque is adopted as a parameter for determining the gain Ai when the pressure value Bi is fixed for each control mode. FIG. 10D shows the pressure value Bi fixed for each control mode. In this case, the case where the slip speed, which is the difference between the engine speed and the input speed of the automatic transmission, is adopted as a parameter for determining the gain Ai is shown.
[0048]
In the case of FIG. 7, as already described, since it is the control accompanying the lock-up operation of the lock-up clutch, in step S4,
P_LONSt_1 = A1 · f (trg) + B1
Based on this, the complete engagement start pressure is determined.
[0049]
In step S4, the complete engagement start pressure P_LONSt_1 is the lock-up pressure P_LUPWhen the full engagement operation of the lockup clutch 5 is started, the process enters step S5, and as described above, the sweep-up gradient dPLON is also dPLONi (i = 1, 2, 3: number i). Corresponds to the control mode of the lockup clutch, where the numeral 1 is control associated with the lockup operation from the unlocked state of the lockup clutch, 2 is the temporary release control associated with the upshift transmission operation of the automatic transmission, 3 Corresponds to the temporary release control associated with the downshift operation of the automatic transmission), and is controlled according to the control mode of the lockup clutch.
[0050]
As a result, the lock-up clutch is fully engaged starting pressure P suitable for ON control of the lock-up clutch from the fully opened state._LONControlled by St_1 and sweep up gradient dPLON1.
[0051]
In step S6, the sweep-up is such that the difference ΔN between the engine speed and the input speed of the automatic transmission is N_LONENDIt continues until it becomes below, and after that, in step S7 and step S8, predetermined time T_LONENDWhen the lock-up clutch 5 is completely engaged after the elapse of time, the process ends.
[0052]
Further, when the torque converter control unit 53 recognizes that the control to be performed from now on is the control associated with the upshift operation of the automatic transmission, the torque converter control unit 53 performs the upshift engagement shown in FIG. The program UEP is read, and the lockup clutch is controlled based on the upshift engagement program UEP.
[0053]
That is, the torque converter control unit 53 executes release control of the lockup clutch at time T2 when the shift determination of the upshift is made in step S9 of the upshift engagement program UEP as shown in FIG. In step S10, at the time T3 when a difference between the engine speed and the transmission input speed starts to occur and the shift control unit 55 determines to start shifting, the process enters step S11, and the lockup pressure P_LUPIs swept down at a predetermined gradient dP_sweepdpn_1, and at step S12 and step S13, a standby pressure P at a predetermined upshift is set._UPWAITTo lower. In step S14, at the time T4 when the shift control determination is made from the transmission control unit 55, the torque converter control unit 53 enters step S4 of the lockup clutch control program RCP shown in FIG. Full engagement start pressure P according to the control mode of the up clutch, that is, the control accompanying the shift operation of the up shift._LONObtain St_2 and calculate the lock-up pressure P_LUPIs supplied to the lock-up clutch 5, and further, in step S5, control is performed with the sweep-up gradient dPLON2 corresponding to the control associated with the upshifting operation.
[0054]
Further, when the torque converter control unit 53 recognizes that the control to be performed from now on is the control accompanying the downshift operation of the automatic transmission, the torque converter control unit 53 performs the downshift engagement shown in FIG. The program DEP is read, and the lockup clutch is controlled based on the downshift engagement program DEP.
[0055]
That is, the torque converter control unit 53 executes the release control of the lockup clutch at the time T5 when the downshift determination is made in step S15 of the downshift engagement program DEP, as shown in FIG. In step S16, a difference between the engine speed and the transmission input speed begins to occur, and the shift start determination of the transmission control unit 55 is established, or the lockup pressure P_LUPIs the standby pressure P during a predetermined downshift._DOWNWAITAt time T6 when the following condition is reached, step S17 is entered, and the lock-up pressure P_LUPA predetermined standby pressure P_DOWNWAITMaintain with. In step S18, at the time T7 when the transmission control unit 55 determines that the shift has been completed, the torque converter control unit 53 enters step S4 of the lockup clutch control program RCP shown in FIG. Full engagement start pressure P according to the control mode of the up clutch, i.e., the control accompanying the shift operation of the down shift._LONFinding St_3, the lockup pressure P_LUPIs supplied to the lock-up clutch 5, and in step S 5, the sweep-up gradient dPLON 3 is controlled according to the control associated with the downshift operation.
[0056]
As a result, the lock-up clutch starts to fully engage in a form that is adapted to the temporary release operation associated with the automatic transmission shift operation such as downshift or upshift when locking up from the normal release state. Pressure P_LONSt_i is calculated, and the calculated complete engagement start pressure P_LONBased on St_i, the complete engagement operation is started from the standby pressure state, so that the complete engagement operation can be performed in a form suitable for each control state, the driving feeling can be improved, and the engagement is completed. This time can be easily set to an optimum state.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a torque converter.
FIG. 2 is a diagram illustrating an example of a hydraulic circuit of a torque converter.
FIG. 3 is a control block diagram illustrating an example of a lockup control device for an automatic transmission.
FIG. 4 is a flowchart illustrating an example of a lockup clutch control program.
FIG. 5 is a flowchart illustrating an example of an upshift engagement program.
FIG. 6 is a flowchart showing an example of a downshift engagement program.
FIG. 7 is a time chart showing a relationship between a change in lockup pressure of a lockup clutch during a lockup operation, an engine speed and a transmission input speed.
FIG. 8 is a time chart showing a relationship between a change in lockup pressure of a lockup clutch during an upshift operation, an engine speed and a transmission input speed.
FIG. 9 is a time chart showing a relationship between a change in lockup pressure of a lockup clutch during a downshift operation, an engine speed and a transmission input speed.
FIG. 10 is a diagram showing various modes when setting a complete engagement start pressure.
FIG. 11 is a time chart showing a relationship between a change in lock-up pressure of a lock-up clutch during a speed change operation, an engine speed and a transmission input speed.
[Explanation of symbols]
1 ... Torque converter
5 …… Lock-up clutch
53... Control mode recognition determination means, engagement start pressure calculation means, engagement execution means (torque converter control section)
P_WAIT...... Standby pressure
P_LONSt_i: Engagement start pressure (complete engagement start pressure)

Claims (7)

In the lockup control device for an automatic transmission that can control the engagement state of the lockup clutch of the torque converter by supplying and controlling the lockup pressure,
The control mode of the lockup clutch is divided into control for engaging the lockup clutch from the disengaged state and control for engaging from the temporarily disengaged state associated with the shift operation of the automatic transmission. Provided with a recognition judgment means,
An engagement start pressure calculating means for calculating an engagement start pressure when the lockup clutch is engaged from the standby pressure state based on the control aspect of the lockup clutch recognized and determined by the control mode recognition determining means. Provided,
An engagement execution means is provided for starting the engagement operation of the lockup clutch from the standby pressure state based on the engagement start pressure according to the control mode of the lockup clutch calculated by the engagement start pressure calculation means. An automatic transmission lockup control device configured as described above. The control mode recognition determination means recognizes and determines temporary release control associated with a shift operation of the automatic transmission separately for control associated with a downshift and control associated with an upshift. The lockup control device for an automatic transmission according to claim 1 . The engagement start pressure calculating means calculates the engagement start pressure P _LON St_i,
P _LON St_i = Ai · f (trg) + Bi
Ai: a predetermined gain based on the control mode of the lockup clutch f (trg): a value obtained as a function of the engine torque trg Bi: a predetermined pressure value based on the control mode of the lockup clutch is obtained by calculation. The lockup control device for an automatic transmission according to claim 1. The engagement initiation pressure calculating means, and the Ai constant, the Bi, by changing according to the engine torque, characterized by calculating said engagement starting pressure P _LON ST_i, according to claim 3, wherein Automatic transmission lockup control device. The engagement start pressure calculating means calculates the engagement start pressure P _LON St_i by making Ai constant and changing Bi according to the difference between the engine speed and the input speed of the automatic transmission. The lockup control device for an automatic transmission according to claim 3 , wherein: The engagement initiation pressure calculating means, and the Bi constant, the Ai, by changing according to the engine torque, characterized by calculating said engagement starting pressure P _LON ST_i, according to claim 3, wherein Automatic transmission lockup control device. The engagement start pressure calculating means calculates the engagement start pressure P _LON St_i by making Bi constant and changing Ai according to the difference between the engine speed and the input speed of the automatic transmission. The lockup control device for an automatic transmission according to claim 3 , wherein:

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