JP2011247285A - Control device of lock-up clutch for vehicle - Google Patents

Abstract

A control device for a lockup clutch for a vehicle that can suppress a decrease in durability of a friction material of a lockup clutch and can improve fuel efficiency by expanding a slip control region.
A surface temperature estimating means 112 always estimates a surface temperature Tsf of a friction material 33 of a lockup clutch 32 under each of the situations when the lockup clutch is released, when slip control is performed, and when fully engaged, The lockup control means 112 controls the operating state of the lockup clutch 32 based on the surface temperature Tsf of the friction material 33 that is always estimated under each of the above conditions. The surface temperature Tsf of the friction material 33 is always estimated even at the time of releasing and fully engaged, and optimum lockup control can be performed based on the surface temperature Tsf of the friction material 33 that is always estimated.
[Selection] Figure 5

Description

  The present invention relates to a control device for a lockup clutch provided in a fluid transmission device including a torque converter.

  A torque converter that functions as a fluid transmission device interposed between an engine and a transmission is well known. Recent torque converters are equipped with a lock-up clutch that mechanically connects the power transmission between the engine and the transmission, and the engagement state of the lock-up clutch is optimally controlled according to the running state of the vehicle. Is done. For the lock-up clutch, for example, the operating state of the lock-up clutch is determined based on the current vehicle speed and the throttle opening from a relation map that defines the operating state of the lock-up clutch composed of the vehicle speed and the throttle opening. . Further, in a relatively low vehicle speed region, a technique has been proposed in which the lockup clutch is slid at a predetermined differential rotation so that the engagement region of the lockup clutch is expanded to improve fuel efficiency. .

  By the way, when the slip control of the lockup clutch is performed for a long time, the durability of the friction plate is lowered by the frictional heat generated from the friction plate of the lockup clutch. On the other hand, in Patent Document 1, a calorific value generated during slip control is calculated, and when the calculated calorific value is equal to or greater than a reference value continues for a set time, the slip control region is changed and slip control is performed. A technique for ending is disclosed. In addition, a technique is disclosed in which slip control is canceled by changing the slip control region when the oil temperature in the torque converter exceeds a reference value for a set time. Further, in Patent Document 2, during the slip control of the lockup clutch, the surface temperature of the friction material of the lockup clutch is estimated and estimated based on the hydraulic oil temperature in the torque converter and the heat generation amount of the lockup clutch. A technique is disclosed in which when the temperature exceeds an allowable temperature, the temperature of the friction material is decreased by releasing the slip control by completely engaging or releasing the lockup clutch.

Japanese Patent No. 3837787 Japanese Patent No. 3476748

  However, in Patent Document 1, the slip control region is determined based on the heat generation amount per unit time / unit area of the lock-up clutch, but actually, the surface temperature of the friction material of the lock-up clutch has a predetermined value. When exceeding, the durability of the friction material decreases. Therefore, for example, in Patent Document 1, slip control may be performed for a long time in a state where the heat generation amount does not exceed the reference value, and at that time, the surface temperature of the friction material of the lockup clutch exceeds the allowable temperature, The durability of the friction material may be reduced. Alternatively, the surface temperature of the friction material is within the allowable temperature range, and the slip control may be prohibited based on the heat generation amount even though the slip control can be performed.

  Further, in Patent Document 1 and Patent Document 2, slip control of the lockup clutch is terminated based on the heat generation amount of the lockup clutch (Patent Document 1) or the surface temperature of the friction material of the lockup clutch (Patent Document 2). However, once the slip control is canceled based on the amount of heat generated or the surface temperature of the friction material, there is a problem that the slip control cannot be performed again. As described above, in Patent Document 1 and Patent Document 2, since the heat generation amount or the surface temperature is estimated only at the time of slip control of the lockup clutch, the surface temperature of the friction material of the lockup clutch decreases after the slip control is released, and slip control is performed. This is because the temperature is not detected and it is not determined that the slip control can be performed even if the above-mentioned is possible. Therefore, for example, in a situation where slip control is continued on an uphill that is longer than expected, a special case where the slip control is canceled urgently when the amount of heat generated or the surface temperature of the friction material exceeds a reference value. If so, the inventions described in Patent Document 1 and Patent Document 2 are effective, but there is a problem in that slip control cannot be performed again during normal traveling, resulting in a reduction in fuel efficiency.

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a vehicle power transmission device including a fluid transmission device having a lock-up clutch on the output side of an engine. Another object of the present invention is to provide a control apparatus for a lockup clutch for a vehicle that can suppress a decrease in the durability of the friction material and can improve fuel efficiency by expanding a slip control region.

  In order to achieve the above object, the gist of the invention according to claim 1 is that (a) an operation state of the lockup clutch in a vehicle provided with a fluid transmission device having a lockup clutch on the output side of the engine. (B) the surface temperature of the friction material of the lockup clutch is determined when the lockup clutch is released, when slip control is performed, and when the lockup clutch is provided with lockup control means for controlling (C) the lockup control means is based on the surface temperature of the friction material that is constantly estimated by the surface temperature estimation means. The operating state of the up clutch is controlled.

  According to a second aspect of the present invention, there is provided the vehicle lockup clutch control device according to the first aspect, wherein the lockup control means is a surface of the friction material estimated by the surface temperature estimation means. The slip control of the lockup clutch is prohibited when the temperature is equal to or higher than a preset first predetermined estimated temperature.

  According to a third aspect of the present invention, there is provided a vehicular lockup clutch control device according to the first or second aspect, wherein the lockup control means is configured to prevent the surface when slip control is prohibited. When the surface temperature of the friction material estimated by the temperature estimating means is equal to or lower than a second predetermined estimated temperature set in advance, the prohibition of slip control is canceled.

  According to a fourth aspect of the present invention, there is provided a vehicular lockup clutch control device according to any one of the first to third aspects, wherein the surface temperature estimating means is configured to completely engage the lockup clutch. The current turbine rotation speed is obtained from a relation map of the surface temperature change amount of the friction material composed of the temperature difference between the surface temperature of the friction material and the hydraulic oil temperature at the time of release and release. And the current surface temperature of the friction material is estimated based on the temperature difference.

  According to a fifth aspect of the present invention, in the control device for a lockup clutch for a vehicle according to the fourth aspect, the relationship map is obtained in advance every time the lockup clutch is completely engaged and released. The relationship map used according to the engagement state of the lockup clutch is switched.

  According to a sixth aspect of the present invention, in the vehicle lock-up clutch control device according to the fourth or fifth aspect, the relationship map is obtained in advance for each driving and driven time of the vehicle, The relationship map used according to the driving state of the vehicle is switched.

  According to the control device for a lockup clutch for a vehicle according to the first aspect of the present invention, the surface temperature estimating means determines the surface temperature of the friction material of the lockup clutch when the lockup clutch is released, during slip control, and completely engaged. Since the lockup control means controls the operating state of the lockup clutch based on the surface temperature of the friction material that is always estimated under each of the above circumstances, only during slip control. In addition, the surface temperature of the friction material is always estimated even when the lock-up clutch is disengaged and fully engaged, and optimum lock-up control can be performed based on the surface temperature of the friction material that is always estimated.

  For example, when the surface temperature of the friction material exceeds the temperature that allows slip control as the surface temperature of the friction material increases during slip control, the lockup control means prohibits the slip control and lowers the surface temperature of the friction material. For example, the durability of the friction material can be suppressed from decreasing. Also, for example, as the surface temperature of the friction material becomes higher than the temperature at which the slip control can be performed during the slip control, the slip control is canceled by the lock-up control means, and then the surface temperature of the friction material decreases and the slip control is performed. When the possible temperature is reached, the surface temperature estimating means always estimates the surface temperature of the friction material even after the slip control is canceled and detects the temperature drop. Fuel efficiency can be improved by resuming the slip control based on the decrease in temperature.

  According to the vehicle lock-up clutch control device of the second aspect of the present invention, when the surface temperature of the friction material estimated by the surface temperature estimating means is equal to or higher than the first predetermined estimated temperature, the lock-up clutch slips. Since the control is prohibited, the durability of the friction material of the lock-up clutch is effectively suppressed.

  According to the vehicle lockup clutch control device of the invention of claim 3, when the slip control is prohibited, the surface temperature of the friction material estimated by the surface temperature estimating means is preset. When the temperature is equal to or lower than the second predetermined estimated temperature, the prohibition of the slip control is released, so that the fuel efficiency improves as the slip control once prohibited is performed again.

  According to the control device for a lockup clutch for a vehicle of the invention according to claim 4, when the temperature difference between the turbine rotational speed and the previously estimated friction material surface temperature and hydraulic oil temperature is detected, the relationship map Based on the above, it is possible to accurately estimate the current surface temperature of the friction material.

  According to the vehicle lock-up clutch control device of the present invention, the relationship map is obtained in advance every time the lock-up clutch is completely engaged and released, and the lock-up clutch is engaged. Since the relationship map to be used is switched according to the combined state, the accuracy of the estimated surface temperature of the friction material is further increased. Specifically, when the lock-up clutch is completely engaged and released, the friction material surface temperature change characteristic varies depending on the contact state between the lock-up clutch friction material and the hydraulic oil in the fluid transmission device. It has been confirmed that there is a difference between full engagement and disengagement. Therefore, the accuracy of the estimated surface temperature of the friction material is further increased by obtaining a relationship map in advance at each time of complete engagement and disengagement and switching to a relationship map according to the engagement state of the lockup clutch. .

  According to the vehicle lock-up clutch control apparatus of the sixth aspect of the invention, the relation map is obtained in advance every time the vehicle is driven and every time it is driven, and is used according to the driving state of the vehicle. Therefore, the accuracy of the estimated surface temperature of the friction material is further increased. Specifically, as the flow of hydraulic oil in the fluid transmission device differs between when the vehicle is driven and when it is driven, the surface temperature change characteristic of the friction material differs between when it is driven and when it is driven. It has been confirmed. Therefore, the accuracy of the estimated surface temperature of the friction material is further increased by obtaining a relation map in advance every time the vehicle is driven and every time it is driven, and switching to the relation map according to the driving state of the vehicle.

1 is a skeleton diagram of a vehicle driving force control device to which the present invention is preferably applied. FIG. 2 is an operation table for explaining operation states of engagement elements when a plurality of shift speeds are established in the stepped automatic transmission provided in the vehicle driving force control apparatus of FIG. 1. FIG. It is a figure which illustrates the signal input into the electronic controller provided in order to control the driving force control apparatus for vehicles of FIG. 1, and the signal output from the electronic controller. FIG. 2 is a diagram illustrating a part of a hydraulic control circuit provided in the vehicle driving force control device of FIG. 1, and more particularly illustrating a circuit for controlling an engagement pressure of a lockup clutch provided in a torque converter. . It is a functional block diagram explaining the principal part of the control function with which the electronic control apparatus of FIG. 4 was equipped. 2 is a relationship map (two-dimensional map) that determines the operating state of the lockup clutch in FIG. 1, where the horizontal axis is the vehicle speed and the vertical axis is the accelerator opening. FIG. 2 is a relationship map showing the amount of change in the surface temperature of the friction material when the lock-up clutch in FIG. 1 is released. FIG. 2 is a relationship map showing the amount of change in the surface temperature of the friction material when the lockup clutch of FIG. 1 is fully engaged. By constantly estimating the surface temperature of the friction material of the lockup clutch by the electronic control device of FIG. 3, and setting the slip control of the lockup clutch optimally based on the estimated surface temperature, the durability of the friction material It is a flowchart for demonstrating the control action which can suppress a fall and can improve a fuel consumption.

  Here, preferably, the first predetermined estimated temperature of the friction material is obtained in advance by experiment or calculation, and is set to a threshold value at which the durability of the friction material decreases. In this way, when the surface temperature of the friction material is equal to or higher than the first predetermined estimated temperature, slip control is prohibited, so that a decrease in the durability of the friction material is suppressed.

  Preferably, the second predetermined estimated temperature is obtained in advance by experiment or calculation, and even if the slip control is resumed, the first predetermined estimated temperature is not reached immediately, and the slip control is suitably performed. Set to a value. In this way, even if slip control is resumed, it is suppressed that slip control is prohibited immediately.

  Preferably, the hydraulic oil temperature required for estimating the surface temperature of the friction material is detected by an oil temperature sensor provided for confirming the controllability of the hydraulic control circuit. In this way, the surface temperature of the friction material and the controllability of the hydraulic control circuit can be confirmed by a common oil temperature sensor, and by providing a dedicated oil temperature sensor for estimating the surface temperature of the friction material. An increase in the number of parts is prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a skeleton diagram of a vehicle power transmission device 8 to which the present invention is preferably applied. FIG. 2 shows a plurality of steps in a stepped automatic transmission 10 provided in the vehicle power transmission device 8. It is an action | operation table | surface explaining the action | operation state of the engagement element at the time of establishing gear stage. This automatic transmission 10 is preferably used for an FF vehicle or the like mounted in the left-right direction (horizontal orientation) of the vehicle, and is configured by a single pinion type first planetary gear device 12 as a main component. A transmission unit 14 and a second transmission unit 20 configured as a Ravigneaux type mainly composed of a double pinion type second planetary gear unit 16 and a single pinion type third planetary gear unit 18 are provided on a coaxial line, and are input. The rotation of the shaft 22 is changed and output from the output rotating member 24. The input shaft 22 corresponds to an input member, and is a turbine shaft of a torque converter 30 that is rotationally driven by an engine 28 that is a driving force source for generating vehicle power. The output rotating member 24 corresponds to an output member of the automatic transmission 10, and an output gear or a differential drive that meshes with a differential driven gear (large-diameter gear) to transmit power to a differential gear device (not shown). It functions as a gear. The output of the engine 28 is transmitted to a pair of drive wheels (front wheels) via the torque converter 30, the automatic transmission 10, the differential gear device, and a pair of axles as drive shafts. Yes. The automatic transmission 10 is substantially symmetrical with respect to the center line, and the lower half of the center line is omitted in FIG.

  The engine 28 is a driving force source of the vehicle power transmission device 8 of the present embodiment, and is an internal combustion engine such as a gasoline engine or a diesel engine that generates driving force of the vehicle by combustion of fuel, for example. The torque converter 30 is provided on the output side of the engine 28. For example, the pump impeller 30a connected to the crankshaft of the engine 28 and the turbine impeller connected to the input shaft 22 of the automatic transmission 10 are provided. 30b and a stator impeller 30c connected to the housing (transmission case) 26 of the automatic transmission 10 through a one-way clutch, and the power generated by the engine 28 is used as the automatic transmission. 10 is a fluid transmission device that transmits the fluid to 10 via a fluid. Further, a lockup clutch 32 (vehicle lockup clutch), which is a direct coupling clutch, is provided between the pump impeller 30a and the turbine impeller 30b. An engaged state (half-engaged state) or a released state is set. When the lockup clutch 32 is completely engaged, the pump impeller 30a and the turbine impeller 30b are integrally rotated.

  The operation table of FIG. 2 summarizes the relationship between the shift speeds established by the automatic transmission 10 and the operation states of the clutch and brake, where “◯” indicates engagement and “◎” indicates engine braking. Only engagement and blank indicate release. The automatic transmission 10 includes a plurality of engagement elements, that is, a first clutch C1, a second clutch C2, a first brake B1, a second brake B2, and a third brake B3 (hereinafter, the clutch C, One of a plurality of predetermined shift speeds is established by selective engagement of the plurality of engagement elements and engagement of the one-way clutch F1 or idling. That is, the clutch C and the brake B provided in the automatic transmission 10 are preferably a hydraulic friction engagement device that is controlled to be engaged by a hydraulic actuator such as a multi-plate clutch or a brake. Engagement / disengagement is switched by the excitation, de-excitation, and current control of the linear solenoid valve of the hydraulic control circuit 40 provided in the transmission device 8, and transient oil pressure at the time of engagement / release is controlled. ing.

  Further, the automatic transmission 10 is related to rotation in one direction between the ring gear R2 of the second planetary gear device 16 (ring gear R3 of the third planetary gear device 18) and the housing 26 which is a non-rotating member. A one-way clutch F1 is provided which is in a combined state but is in an idle state with respect to rotation in the reverse direction. With this configuration, as shown in FIG. 2, the one-way clutch F1 is activated, that is, engaged only when the vehicle power transmission device 8 is driven, and is idled when not driven. In particular, when the vehicle starts, kicks down, or the like, the automatic transmission 10 is operated to be in an engaged state in order to establish the first shift stage “1st”.

  In the automatic transmission 10, the first speed change according to the combination of the connected states of the rotating elements (sun gears S <b> 1 to S <b> 3, carriers CA <b> 1 to CA <b> 3, ring gears R <b> 1 to R <b> 3) of the first transmission unit 14 and the second transmission unit 20. Six forward shift stages from the stage “1st” to the sixth shift stage “6th” are selectively established, and the reverse shift stage of the reverse shift stage “R” is established. As shown in FIG. 2, for example, in the forward gear stage, the first speed gear stage “1st” is established by the engagement of the first clutch C1 and the second brake B2. Further, the second gear stage “2nd” is established by the engagement of the first clutch C1 and the first brake B1. The third speed gear stage “3rd” is established by engagement of the first clutch C1 and the third brake B3. The fourth gear stage “4th” is established by engagement of the first clutch C1 and the second clutch C2. Further, the fifth gear "5th" is established by engagement of the second clutch C2 and the third brake B3. The sixth gear stage “6th” is established by engagement of the second clutch C2 and the first brake B1. Further, the reverse gear stage “R” is established by the engagement of the second brake B2 and the third brake B3, and the neutral state is established when both the clutch C and the brake B are released. Yes. As described above, in the automatic transmission 10 according to the present embodiment, the one-way clutch F1 is provided in parallel with the second brake B2 that establishes the first shift stage “1st”. It is not always necessary to engage the second brake B2 during acceleration). The gear ratios of the respective gears are the gear ratios of the first planetary gear device 12, the second planetary gear device 16, and the third planetary gear device 18 (= the number of teeth of the sun gear / the number of teeth of the ring gear) ρ1, It is determined appropriately by ρ2 and ρ3.

  FIG. 3 shows signals input to an electronic control device 34 (control device) provided in the vehicle power transmission device 8 for controlling the vehicle power transmission device 8 and the electronic control device 34. The signal is illustrated. The electronic control unit 34 includes a so-called microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like, and performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. As a result, various controls such as drive control of the engine 28, stepped shift control in the automatic transmission 10, and lock-up clutch pressure control of the torque converter 30 described later are executed. A control device for controlling the drive of the engine 28 and a control device for controlling the operation of the automatic transmission 10 and the like may be provided separately.

  As shown in FIG. 3, the electronic control device 34 is supplied with various signals related to the vehicle power transmission device 8 from each sensor, switch, and the like. For example, a signal indicating the engine water temperature, a signal indicating the number of operations at the shift position of the shift lever, the “M” position, and the like, an engine speed Ne (= pump) which is the rotational speed of the engine 28 detected by the engine speed sensor 36 A signal representing the rotational speed Np) of the impeller 30a, a signal representing the rotational speed Nt of the turbine impeller 30b detected by the turbine rotational speed sensor 38, a signal representing the speed of the driving wheel corresponding to the vehicle speed V, M mode (manual) (Transmission mode) A signal indicating ON / OFF of the switch, a signal indicating the operation of the air conditioner, and an ATF oil temperature Toil (operating oil temperature) used for the control operation of the automatic transmission 10 detected by the ATF oil temperature sensor 39 Signals that indicate ECT switch on / off, signals that indicate side brake operation, foot brake operations A signal indicating a brake master cylinder pressure corresponding to the foot brake, a signal indicating a catalyst temperature, a signal indicating an accelerator opening Acc corresponding to an operation amount of an accelerator pedal (not shown) detected by an accelerator opening sensor, a cam A signal representing the angle, a signal representing the snow mode setting, a signal representing the longitudinal acceleration G of the vehicle, a signal representing the auto cruise traveling, a signal representing the weight (vehicle weight) of the vehicle, and the like are supplied.

  Various control signals are output from the electronic control unit 34 in order to control the driving of the vehicle power transmission device 8. For example, a drive signal to a throttle actuator for operating a throttle valve opening θth of an electronic throttle valve provided in an intake pipe of the engine 28, a boost pressure adjustment signal for adjusting a boost pressure, and the like to the engine 28 A control signal for the amount of fuel supplied into the cylinder of the engine by the fuel injection device for controlling the fuel injection of the engine, an ignition signal for instructing the ignition timing of the engine 28 by the ignition device, and an electric air conditioner drive for operating the electric air conditioner A signal, a shift position (operation position) display signal for operating the shift indicator, a gear ratio display signal for displaying the gear ratio, a snow mode display signal for displaying the snow mode, and the hydraulic control circuit 40 A signal for regulating the line hydraulic pressure PL by a regulator valve (pressure regulating valve) provided in the A valve command signal for operating an electromagnetic control valve (linear solenoid valve) included in the hydraulic control circuit 40 in order to control a hydraulic actuator of a hydraulic friction engagement device provided in the transmission 10 or the like, FIG. A lockup switching command signal for operating a switching electromagnetic solenoid valve 66 described later, a slip control command signal for operating a slip control solenoid valve 70 described later using FIG. 4 and the like, and preventing wheel slipping during braking. An ABS operation signal for operating the ABS actuator, an M mode display signal for indicating that the M mode is selected, and an electric oil pump 44 that is an output source of the original pressure provided in the hydraulic control circuit 40 are operated. Drive command signal, signal for driving electric heater, computer for cruise control control The signal etc. are output respectively.

  FIG. 4 is a diagram showing a part of the hydraulic control circuit 40 provided in the vehicle power transmission device 8, and in particular, a circuit for controlling the engagement pressure of the lockup clutch 32 provided in the torque converter 30. FIG. In the hydraulic control circuit 40 of FIG. 4, circuits used for other controls such as a circuit for controlling the operation of the hydraulic friction engagement device for shifting the automatic transmission 10 are omitted. ing.

  As shown in FIG. 4, the hydraulic control circuit 40 is provided with an electric oil pump 44 driven by an electric motor (not shown), for example, in order to suck and pressure-feed hydraulic oil circulated to the oil pan 42. The hydraulic oil pumped from the electric oil pump 44 is regulated to the first line pressure PL1 by a relief type first pressure regulating valve 46. The first pressure regulating valve 46 generates a first line pressure PL1 that increases in response to the throttle pressure output from a throttle valve opening detection valve (not shown) and outputs the first line pressure PL1 to the first line oil passage 48. Similarly, the second pressure regulating valve 50 is a relief type pressure regulating valve, which regulates hydraulic oil discharged (relieved) for pressure regulation from the first pressure regulating valve 46 based on the throttle pressure. Thus, the second line pressure PL2 corresponding to the output torque of the engine 28 is generated. The third pressure regulating valve 52 is a pressure reducing valve that uses the first line pressure PL1 as a source pressure, and generates a constant modulator pressure Pm having a preset magnitude. The first line pressure PL1 is supplied as a source pressure or the like of a shift control hydraulic circuit (not shown) for controlling the gear stage of the automatic transmission. Further, in this embodiment, a hydraulic control circuit of the type that generates the original pressure by the electric oil pump 44 will be described, but it is provided with a mechanical oil pump that is driven by the engine 28 to generate the original pressure. There may be.

  Further, as shown in FIG. 4, the lock-up clutch 32 is connected via an oil pressure Pon in an engagement side oil chamber 56 to which hydraulic oil is supplied via an engagement side oil passage 54 and a release side oil passage 58. This is a hydraulic friction engagement clutch in which the friction material 33 is frictionally engaged with the front cover 62 by a differential pressure ΔP (Pon−Poff) with respect to the hydraulic pressure Poff in the release side oil chamber 60 to which hydraulic oil is supplied. The operating conditions of the torque converter 30 are, for example, (a) a so-called lockup-off in which the differential pressure ΔP is negative and the lockup clutch 32 is released, and (b) the differential pressure ΔP is zero or more. So-called slip state in which the lock-up clutch 32 is in a semi-engaged state, and (c) so-called lock in which the differential pressure ΔP is at a maximum value and the lock-up clutch 32 is in a fully engaged state. It is roughly divided into three conditions of up-on.

Further, the hydraulic control circuit 40 is turned on / off by a switching electromagnetic solenoid 64 to supply a switching signal pressure _PSW , and the lock control circuit 40 according to the switching signal pressure _PSW. A clutch switching valve 68 for switching to either the off-side position (OFF) where the up clutch 32 is disengaged or the on-side position (ON) where it is engaged is supplied from the electronic control unit 34. The slip-up solenoid valve 70 that outputs a signal pressure P _SLU for controlling the pressure according to the driving current and the clutch switching valve 68 engage the lockup clutch 32 (a state corresponding to the on-side position). ), The lock-up clutch 32 switches the operating state of the lock-up clutch 32 in the range from slip state to lock-up on. A control valve 72 is provided.

The clutch switching valve 68 is for switching the lock-up clutch 32 to one of an engaged state and a released state, and includes a release side port 74 communicating with the release side oil chamber 60, and the engagement side oil chamber. 56, the engagement side port 76 communicating with the input line 78, the input port 78 to which the second line pressure PL2 is supplied, and the hydraulic oil in the engagement side oil chamber 56 is discharged when the lockup clutch 32 is released, A discharge port 80 to which hydraulic oil discharged from the second pressure regulating valve 50 is supplied when the lockup clutch 32 is engaged, and a bypass port communicating with the release-side oil chamber 60 when the lockup clutch 32 is engaged. 82, a relief port 84 to which hydraulic oil discharged for pressure regulation from the second pressure regulating valve 50 is supplied, and a sprocket for switching the states of the plurality of ports And Rubenko 86, a spring 88 which urges the spool valve element 86 off-side position, the switching signal pressure P _SW from the switching solenoid valve 66 to the end portion of the spool 86 an oil chamber 90 for receiving the switching signal pressure P _SW in order to generate a thrust directed by the action to the on-side position, a. In FIG. 4, the left side of the center line shows a state in which the spool valve element 86 is positioned at the off-side position (OFF) where the lockup clutch 32 is released, and the right side of the center line is in the engaged state This shows a state where the spool valve element 86 is positioned at the ON position (ON).

The lock-up control valve 72 includes a spool valve element 92 that switches the state of the valve, a spring 94 that applies a thrust toward the slip valve element 92 toward the slip side position (SLIP), and the spool valve element 92 on the slip side. In order to urge the spool valve element 92 to the fully engaged side position (ON), the oil chamber 96 that receives the hydraulic pressure Pon in the engagement side oil chamber 56 of the torque converter 30 to urge toward the position. Are output from the slip control solenoid valve 70 for energizing the spool valve element 92 toward the on-side position, and an oil chamber 98 for receiving the hydraulic pressure Poff in the release-side oil chamber 60 of the torque converter 30. an oil chamber 100 for receiving the signal pressure P _SLU, an input port 102 of the second line pressure PL2 pressure regulated by the second pressure regulating valve 50 is supplied The input port 102 and control port 104 that communicates when the spool 92 is positioned in a slip-side position, and a drain port 106, and. 4 shows a state where the spool valve element 92 is positioned at the slip side position (SLIP) on the left side of the center line, and the spool valve element 92 is positioned on the right side of the center line at the complete engagement side position (ON). Shows the state where is located.

The slip control solenoid valve 70 outputs a signal pressure P _SLU for controlling the engagement pressure of the lockup clutch 32 when the lockup clutch 32 is engaged based on a command from the electronic control unit 34. To do. In other words, a constant modulator pressure Pm generated by the third pressure regulating valve 52 is used as a source pressure, and the modulator pressure Pm is reduced to generate a signal pressure P _SLU . The switching electromagnetic solenoid valve 66 uses the switching signal pressure P _SW as the drain pressure in the non-excited state (off state), but sets the switching signal pressure P _SW as the modulator pressure Pm in the excited state (on state). , And act on the oil chamber 90 of the clutch switching valve 68. When the modulator pressure Pm is supplied to the oil chamber 90, the spool valve element 86 of the clutch switching valve 68 is moved to the ON side position (ON) against the urging force of the spring 88. On the other hand, when the drain pressure is supplied to the oil chamber 90, the spool valve element 86 of the clutch switching valve 68 is moved to the off-side position (OFF) according to the urging force of the spring 88. In the following description, described as switching signal pressure P _SW when the modulator pressure Pm is supplied as a switching signal pressure P _SW is supplied, drain pressure is supplied as a switching signal pressure P _SW In this case, since the slip control solenoid valve 70 is not substantially affected, the switching signal pressure _PSW is not supplied.

In the clutch switching valve 68, when the switching electromagnetic solenoid valve 66 is excited and the switching signal pressure _PSW is supplied to the oil chamber 90 and the spool valve element 86 is positioned at the ON side position, the input port The second line pressure PL <b> 2 supplied to 78 is supplied from the engagement side port 76 to the engagement side oil chamber 56 through the engagement side oil passage 54. The second line pressure PL2 supplied to the engagement side oil chamber 56 becomes the hydraulic pressure Pon. At the same time, the release-side oil chamber 60 is communicated with the control port 104 of the lock-up control valve 72 through the release-side oil passage 58, the release-side port 74, and the bypass port 82. Then, the hydraulic pressure Poff in the release-side oil chamber 60 is adjusted by the lockup control valve 72, and the operating state of the lockup clutch 32 is switched in the range of slip state to lockup on.

Specifically, when the spool valve element 76 of the clutch switching valve 68 is biased to the on-side position, that is, when the lockup clutch 32 is switched to the engaged state, the lockup control valve 72, the signal pressure P _SLU for moving the spool valve element 92 to the fully engaged position (ON) is not supplied to the oil chamber 100, and the spool valve element 92 is moved to the slip position by the thrust of the spring 94. (SLIP), the second line pressure PL2 supplied to the input port 102 passes from the control port 104 via the bypass port 82, and passes from the release side port 74 through the release side oil passage 58 to the release side oil chamber 60. Supplied. In this state, the differential pressure ΔP is controlled by the signal pressure P _{SLU of the} slip control solenoid valve 70 to control the slip state of the lockup clutch 32.

When the spool valve element 76 of the clutch switching valve 68 is biased to the on position (ON), the spool valve element 92 is moved to the fully engaged position (ON) in the lockup control valve 72. When the signal pressure P _SLU for movement is supplied to the oil chamber 100, the second line pressure PL2 is not supplied from the input port 102 to the release side oil chamber 60, and the hydraulic oil in the release side oil chamber 60 is supplied. Is discharged from the drain port 106. As a result, the differential pressure ΔP is maximized and the lockup clutch 32 is fully engaged. Further, when the lock-up clutch 32 is in the slip state or the completely engaged state, the spool valve element 86 of the clutch switching valve 68 is positioned at the on-side position, so that the relief port 84 and the discharge port 80 are communicated with each other. . As a result, the hydraulic oil discharged from the second pressure regulating valve 50 is supplied to the lubricating oil supply oil passage (not shown) via the clutch switching valve 68.

On the other hand, in the clutch switching valve 68, if the switching signal pressure _PSW is not supplied to the oil chamber 90 and the spool valve element 86 is positioned at the off-side position (OFF) by the urging force of the spring 88, the input The second line pressure PL <b> 2 supplied to the port 78 is supplied from the release side port 74 to the release side oil chamber 60 through the release side oil passage 58. The hydraulic oil in the engagement side oil chamber 56 is supplied to the engagement side port 76 through the engagement side oil passage 54 and supplied from the discharge port 80 to a lubricating oil supply oil passage (not shown). Thereby, the lockup clutch 32 is locked up.

  FIG. 5 is a functional block diagram for explaining the main part of the control function provided in the electronic control unit 34. The vehicle state detecting means 107 shown in FIG. 5 is automatically associated with related values related to the running state of the vehicle, such as a shift position of a shift lever (not shown), an accelerator opening Acc of an accelerator pedal, an engine speed Ne, and a vehicle speed V. The rotational speed Nout of the output shaft of the transmission 10, the turbine rotational speed Nt, the ATF oil temperature Toil, the engine torque Te, and the like are detected. Further, the vehicle state detection means 107 determines whether the vehicle (the vehicle power transmission device 8) is in a driving state or a driven state, for example, whether or not the accelerator opening Acc is zero, or a foot brake operation. Is determined based on a signal or the like representing.

  The shift control means 108 controls the shift operation of the automatic transmission 10. That is, based on a predetermined relationship (shift map, etc.), the automatic transmission 10 described above is based on a lever position of a shift lever (not shown), an accelerator pedal operation amount (accelerator opening Acc), a vehicle speed V, and the like. It is determined which of the first shift speed “1st” to the sixth shift speed “6th” or the reverse shift speed “R” should be established, and the determined shift speed is established. Engagement or release of the clutch C and the brake B is controlled via the hydraulic control circuit 40.

  The lock-up control means 109 determines the actual vehicle speed V and the accelerator opening from the relation map (operating region map) consisting of the vehicle speed V and the accelerator opening Acc for determining the predetermined operating state of the lock-up clutch 32 shown in FIG. The operating state of the lockup clutch 32 is determined based on the degree Acc, and the lockup clutch 32 is controlled to the operating state. FIG. 6 is a two-dimensional map (operation region map) that determines the operation state (operation region) of the lockup clutch 32, in which the horizontal axis is the vehicle speed V and the vertical axis is the accelerator opening Acc. Based on the actual vehicle speed V and the accelerator opening degree Acc, the lockup clutch 32 is locked up (completely engaged), slip controlled (flex lockup control), and locked up off (released) based on the operating region map. It is determined either.

  For example, the lockup control means 109 sets the differential pressure ΔP (Pon−Poff) of the lockup clutch 32 to the maximum value when the vehicle running state enters the lockup on region shown in FIG. The operating state of the hydraulic control circuit 40 is controlled so as to be in a completely engaged state. Further, the lock-up control means 109 controls the hydraulic control circuit 40 so that the differential pressure ΔP (Pon−Poff) of the lock-up clutch 32 becomes zero when the running state of the vehicle enters the lock-up off region shown in FIG. Control. Further, when the vehicle running state enters the slip control region shown in FIG. 6, the lockup control means 109 sets the slip amount ΔN (= Ne−Nt) of the lockup clutch 32 to a predetermined slip amount ΔN set in advance. Thus, the differential pressure ΔP is feedback-controlled.

  The lock-up state determination means 110 indicates that the current operation state of the lock-up clutch 32 is a lock-up on state (fully engaged state) in which the lock-up clutch 32 is completely engaged, and the lock-up clutch 32 is in a half-engaged state. It is determined whether the slip control state is in the locked state or the lockup off state (released state) in which the lockup clutch 32 is in the released state. The lockup state determination means 110 makes the above determination based on, for example, a lockup switching command signal output to the switching electromagnetic solenoid valve 66 for switching the operation state of the lockup clutch 32 and the engagement side oil chamber 56 at the time of slip control. The determination is made based on a slip control command signal output to the slip control solenoid valve 70 for controlling the differential pressure ΔP (Pon−Poff) between the hydraulic pressure Pon and the hydraulic pressure Poff of the release side oil chamber 58.

For example, if the lock-up switching command signal for setting the switching signal pressure P _SW output from switching solenoid valve 66 and drain pressure is outputted, the lock-up clutch 32 is determined to lock-up off state and, When a lockup switching command signal with the switching signal pressure _PSW as the modulator pressure Pm is output, it is determined that the lockup clutch 32 is in the lockup on state or the slip control state. Further, when a lockup switching command signal is output with the switching signal pressure _PSW as the modulator pressure Pm, the signal pressure _PSLU is completely _engaged with the lockup control valve 72 from the slip control solenoid valve 70. When the slip control command signal for outputting the preset full engagement hydraulic pressure for switching to the side position (ON) is output, it is determined that the lockup clutch 32 is in the lockup ON state. On the other hand, in the case where a lockup switching command signal for outputting the switching signal pressure P _SW as the modulator pressure Pm is output, the signal pressure P _SLU from the slip control solenoid valve 70 is set to a hydraulic pressure _lower than the fully engaged hydraulic pressure. Is output, the lockup clutch 32 is determined to be in the slip control state.

  The surface temperature estimation means 112 estimates the surface temperature Tsf of the friction material 33 of the lockup clutch 32 according to the operating state of the lockup clutch 32 determined by the lockup state determination means 110. The surface temperature estimation means 112 is a temperature estimation means 114 at the time of release for estimating the surface temperature Tsf of the friction material 33 when the lockup clutch 32 is released, and a friction material when the lockup clutch 32 is fully engaged. 33 is provided with a temperature estimation means 116 at the time of engagement for estimating the surface temperature Tsf of 33 and a temperature estimation means 118 at the time of slip for estimating the surface temperature Tsf of the friction material 33 when the lockup clutch 32 is slip-controlled. Then, the surface temperature estimating means 112 determines the operating state of the lockup clutch 32 by the lockup state determining means 110, and according to the respective circumstances at that time, the release temperature estimating means 114, the engagement temperature estimating means. The surface temperature Tsf of the friction material 33 is always estimated by switching 116 and the slip temperature estimation means 118 and executing them.

The released temperature estimating means 114 estimates the surface temperature Tsf of the friction material 33 when the lockup clutch 32 is released. The release temperature estimation means 114 sequentially estimates (calculates) the surface temperature Tsf of the friction material 33 at predetermined time steps (for example, about 16 ms) based on the following equation (1). In the following equation (1), Tsfi is the surface temperature Tsf of the friction material 33 estimated this time, and Tsfi-1 is the surface temperature of the friction material 33 estimated in the previous time step. Α is a temperature change amount (surface temperature change amount) set for each time step when the lock-up clutch 32 is released, and a temperature change amount (surface temperature) obtained in advance and stored in the storage unit 120. Change amount) based on the relationship map. The calculated surface temperature Tsfi is set to the previous surface temperature Tsfi-1 when calculating the surface temperature Tsfi of the next time step.
Tsfi = Tsfi-1−α (1)

  FIG. 7 shows a relationship map (two-dimensional map) used when determining the temperature change amount α. The relationship map is obtained in advance by experiment or calculation in a state where the lockup clutch 32 is released, and a temperature difference ΔT between the turbine rotational speed Nt, the surface temperature Tsf of the friction material 33 and the ATF oil temperature Toil. It is expressed by a two-dimensional map showing the surface temperature change amount α of the friction material 33 constituted by (Tsf−Toil).

  The release temperature estimation means 114 calculates a temperature difference ΔT (Tsfi-1−Toil) between the previously estimated surface temperature Tsfi-1 and the current ATF oil temperature Toil, and calculates the calculated temperature difference ΔT from the relationship map. The temperature change amount α is determined by performing linear interpolation based on the current turbine rotational speed Nt. Then, the release temperature estimation means 114 estimates the current surface temperature Tsfi based on the determined temperature change amount α and the previously estimated surface temperature Tsfi-1 from the equation (1). The turbine rotation speed Nt and the ATF oil temperature Toil are detected by the vehicle state detection means 107.

  Here, the ATF oil temperature Toil is specifically detected by the ATF oil temperature sensor 39, and the ATF oil temperature sensor 39 is discharged from the electric oil pump 44 in the hydraulic control circuit 40, for example, as shown in FIG. It arrange | positions at the 1st line oil path 48 which is a part. Comparing the ATF oil temperature Toil in the first line oil passage 48 and the ATF oil temperature Toil in the torque converter 30 (hereinafter referred to as Ttc for distinction), the hydraulic oil in the first line oil passage 48 is the torque converter. Since heat exchange is performed before reaching 30, the ATF oil temperature Toil and the ATF oil temperature Ttc in the torque converter do not match, but the above-described temperature difference ΔT (Tsf−Toil) and the turbine rotational speed Nt It was experimentally confirmed that the surface temperature Tsf of the friction material 33 estimated on the basis of the relationship map constituted by: substantially matches the surface temperature Tsf actually detected by a sensor or the like. That is, even if the ATF oil temperature Ttc in the torque converter closest to the friction material 33 is not directly detected, the surface temperature Tsf of the friction material 33 can be accurately detected by detecting the ATF oil temperature Toil of the first line oil passage 48. It was confirmed that it was estimated. The detected ATF oil temperature Toil is used for confirming the controllability of the hydraulic control circuit 40 including the automatic transmission 10, and the ATF oil temperature sensor 39 is provided conventionally. is there. Thus, when estimating the surface temperature Tsf of the friction material 33, there is no need to provide a dedicated oil temperature sensor for detecting the oil temperature in the torque converter 30, and a common ATF oil for confirming the controllability of the hydraulic control circuit 40 is obtained. The surface temperature Tsf can be estimated using the temperature sensor 39.

  The relation map is experimentally obtained in advance every time the vehicle is driven and every time it is driven, and is stored in the storage means 120. The relation map is related to the vehicle driving state detected by the vehicle state detecting means 107. The map is switched and the surface temperature Tsfi is estimated based on the switched relationship map. When the vehicle is in a driving state, the torque converter 30 transmits power from the pump impeller 30a side, whereas when the vehicle is in a driven state, power is transmitted from the turbine impeller 30b side. This is because the characteristics of the temperature change amount α are different based on the difference in the flow of the hydraulic oil in 30.

Further, the releasing temperature estimating means 114 measures an elapsed time ta after the lock-up clutch 32 is released, and if the elapsed time ta exceeds a preset predetermined elapsed time ta1, the following equation (1 ′ ) To estimate the surface temperature Tsf of the friction material 33. Here, A is a correction value, which is experimentally obtained in advance and stored in the storage unit 120.
Tsf = Toil + A (1 ')

The engagement temperature estimation means 116 estimates the surface temperature Tsf of the friction material 33 when the lockup clutch is completely engaged. The engagement temperature estimation means 116 sequentially estimates (calculates) the surface temperature Tsf of the friction material 33 at predetermined time steps (for example, about 16 ms) based on the following equation (2). In the following equation (2), Tsfi is the surface temperature Tsf of the friction material 33 estimated this time, and Tsfi-1 is the surface temperature Tsf of the friction material 33 estimated in the previous time step. Β is a temperature change amount (surface temperature change amount) set for each time step when the lockup clutch 32 is engaged, and a temperature change amount (surface surface) obtained in advance and stored in the storage unit 120. It is determined based on a relationship map of (temperature change amount). The calculated surface temperature Tsfi is set to the previous surface temperature Tsfi-1 when calculating the surface temperature Tsfi of the next time step.
Tsfi = Tsfi-1−β (2)

  FIG. 8 shows a relationship map (two-dimensional map) used when determining the temperature change amount β. The relationship map is obtained in advance by experiment or calculation in a state where the lockup clutch 32 is completely engaged, and the temperature between the turbine rotation speed Nt, the surface temperature Tsf of the friction material 33 and the ATF oil temperature Toil. It is represented by a two-dimensional map indicating the surface temperature change amount β of the friction material 33 constituted by the difference ΔT (Tsf−Toil).

  The engagement temperature estimation means 116 calculates a temperature difference ΔT (= Tsfi-1−Toil) between the previously estimated surface temperature Tsfi-1 and the current ATF oil temperature Toil, and the temperature calculated from the relationship map. The temperature change amount β is determined by performing linear interpolation based on the difference ΔT and the current turbine rotational speed Nt. Then, the engagement temperature estimation means 116 estimates the current surface temperature Tsfi based on the determined temperature change β and the previously estimated surface temperature Tsfi-1 from the equation (2). The turbine rotation speed Nt and the ATF oil temperature Toil are detected by the vehicle state detection means 107.

  Further, the relationship map is experimentally obtained in advance and stored in the storage means 120 every time the vehicle is driven and driven, similarly to when the lockup clutch is released, and is detected by the vehicle state detection means 107. The relationship map is switched according to the driving state of the vehicle, and the surface temperature Tsfi is estimated based on the switched relationship map. When the vehicle is in a driving state, the torque converter 30 transmits power from the pump impeller 30a side, whereas when the vehicle is in a driven state, power is transmitted from the turbine impeller 30b side. This is because the characteristics of the temperature change amount β are different based on the difference in the flow of the hydraulic oil in the inside.

Further, the engagement temperature estimation means 116 measures the elapsed time tb after the lockup clutch 32 is completely engaged, and if the elapsed time tb exceeds a preset elapsed time tb1, the following equation ( 2 ′), the surface temperature Tsf of the friction material 33 is estimated. Here, B is a correction value, which is experimentally obtained in advance and stored in the storage unit 120.
Tsf = Toil + B (2 ')

  Here, comparing the relationship map when the lockup clutch is engaged in FIG. 8 with the relationship map when the lockup clutch is released in FIG. 7, the temperature change amount β when the lockup clutch is engaged is as follows. Is smaller than the temperature change amount α. From the above, a relationship map (FIGS. 7 and 8) that differs between when the lockup clutch 32 is released and when it is fully engaged is obtained in advance, and depending on whether the lockup clutch 32 is in the released state or the fully engaged state. Thus, the accuracy of the surface temperature Tsf of the friction material 33 is increased.

  Note that the relationship map in FIG. 7 is obtained offline in advance by experiments and calculations under the condition in which the lockup clutch 32 is released, and the relationship map in FIG. 8 is in a condition in which the lockup clutch 32 is completely engaged. As described above, the temperature change amounts (α, β) are different from each other. For example, when the lock-up clutch is released, the contact area between the friction material 33 and the hydraulic oil in the torque converter 30 is large, so that the amount of heat exchange between the two increases. Because the material 33 and the front cover 62 of the torque converter 30 are in close contact with each other, the contact area between the friction material 33 and the hydraulic oil is relatively small, and the amount of heat exchange is smaller than when the lockup clutch is released. .

The slip temperature estimation means 118 sequentially estimates the surface temperature Tsf of the friction material 33 during the slip control of the lockup clutch 32 at each time step. Hereinafter, a known estimation method for the surface temperature Tsf of the friction material 33 during the slip control will be described as an example. First, the slip temperature estimation means 118 calculates a lockup clutch transmission torque _TLC applied to the friction material 33 during slip control. The lockup clutch transmission torque T _LC is calculated based on the following equation (3). Here, Te corresponds to the output torque of the engine 28, and the actual accelerator opening Acc and engine speed are calculated from the relationship map of the engine torque Te, which is determined in advance from the accelerator opening Acc and the engine speed Ne. It is obtained based on Ne. Or you may detect directly, for example by providing a torque sensor in the crankshaft of the engine 12. FIG. Further, c corresponds to the capacity coefficient of the torque converter 30 and is obtained from the performance curve of the torque converter 30 stored in the storage unit 120 in advance. Note that the second term (= c × Ne ² ) in the right term of the following expression (3) corresponds to the torque transmitted by the torque converter 30. That is, the lockup clutch transmission torque T _LC corresponds to the difference between the engine torque Te and the torque transmitted by the torque converter 30.
T _LC = Te−c × Ne ² (3)

When the slip temperature estimation means 118 calculates the lockup clutch transmission torque T _LC , the slip temperature estimation means 118 calculates the heat generation amount Q _LC of the lockup clutch 32 based on the following equation (4). Here, ΔN corresponds to the differential rotation (= Ne−Nt) between the engine rotation speed Ne and the turbine rotation speed Nt, in other words, the slip amount ΔN of the lockup clutch 32. Further, dt corresponds to a calculation time step (for example, 16 ms).
Q _LC = T _LC × (π / 30) × ΔN × dt (4)

Further, when the calorific value Q _LC is calculated, the slip temperature estimating means 118 estimates the surface temperature Tsf of the friction material 33 based on the following equation (5). Here, M _LC is the heat capacity of the part sliding with the friction material 33, and is obtained in advance by experiment or calculation and stored in the storage means 120 as a constant. ΔT corresponds to the temperature difference between the surface temperature Tsfi-1 estimated in the previous time step and the ATF oil temperature Toil. In addition, k corresponds to a cooling correction coefficient based on a temperature difference ΔT between the surface temperature Tsfi-1 and the ATF oil temperature Toil, and is obtained in advance by experiment or calculation. For example, as a unified map based on the turbine rotational speed Nt, It is stored in the storage means 120.
Tsfi = Tsfi-1 + (Q _LC −k × ΔT) / M _LC (5)

  The slip temperature estimation means 118 sequentially calculates the current surface temperature Tsfi of the friction material 33 from the equation (5) for each time step. The calculated surface temperature Tsfi is set to the previous surface temperature Tsfi-1 when calculating the surface temperature Tsfi of the next time step.

The slip temperature estimation means 118 can be calculated based on the following equation (6) instead of the above equations (3) to (5). Here, γa corresponds to the specific heat of the hydraulic oil, γc corresponds to the specific heat of the lockup clutch 32, and M corresponds to the mass correction coefficient. The specific heat γa and the specific heat γc are physical property values, and the mass correction coefficient M is a value obtained experimentally in advance.
Tsfi = Tsfi-1 + ΔT × γa / γc × M (6)

  The lockup control means 109 controls the operating state of the lockup clutch 32 based on the surface temperature Tsf of the friction material 33 estimated by the surface temperature estimation means 112. For example, the lockup control unit 109 includes a slip control prohibiting unit 122 and a slip control permission unit 124. The slip control prohibiting means 122 is a first predetermined estimation for prohibiting slip control in which the surface temperature Tsf of the friction material 33 estimated by the surface temperature estimating means 112 is preset when the lockup clutch 32 is in the slip control state. Slip control is prohibited based on whether or not the temperature Tend has been reached. Specifically, the slip control prohibiting means 122 outputs a command signal for prohibiting the slip control of the lockup clutch 32 to the lockup control means 109 when the estimated surface temperature Tsf is equal to or higher than the first predetermined estimated temperature Tend. . The lockup control unit 109 receives the command signal for prohibiting the slip control from the slip control prohibiting unit 122 and switches the lockup clutch 32 to the disengagement or complete engagement, thereby prohibiting the slip control. The first predetermined estimated temperature Tend is obtained in advance by experiments and calculations, and is set to a threshold (for example, about 200 ° C.) at which the durability of the friction material 33 decreases.

  When the slip control prohibiting means 122 prohibits the slip control of the lockup clutch 32, the slip control permitting means 124 is sequentially estimated by the surface temperature estimating means 112 according to the subsequent decrease in the surface temperature Tsf of the friction material 33. When the surface temperature Tsf of the friction material 33 is equal to or lower than a second predetermined estimated temperature Tsts that permits a preset slip control, a command signal that cancels the prohibition of the slip control and permits the slip control is locked up. Output to 109. The lockup control means 109 receives a command signal for permitting slip control from the slip control permission means 124, and when the current running state is in the slip control region shown in FIG. To resume. The second predetermined estimated temperature Tsts for canceling the prohibition of the slip control is set to a temperature lower by a predetermined value than the first predetermined estimated temperature Tend for prohibiting the slip control. By setting in this way, even if the slip control is resumed, the slip control is prevented from being prohibited immediately. Note that the slip control prohibiting means 122 and the slip control allowing means 124 can be implemented because the surface temperature estimating means 112 always estimates the surface temperature Tsf of the friction material 33.

  FIG. 9 shows the main part of the control operation of the electronic control unit 34, that is, the surface temperature Tsf of the friction material 33 of the lockup clutch 32 at all times, and the slip control of the lockup clutch 32 based on the estimated surface temperature Tsf. Is a flowchart for explaining a control operation capable of suppressing the decrease in the durability of the friction material 33 and improving the fuel efficiency by optimally setting the value of, for example, extremely high, for example, about several msec to several tens msec. It is implemented repeatedly with a short cycle time.

  First, in step SA1 (hereinafter, step is omitted) corresponding to the lockup state determination means 110, the lockup clutch 32 is in the lockup on state (fully engaged state), the slip control state (FL / U control, flex lock). Up control) or lock-up off state (release state). When it is determined that the lockup clutch 32 is in the released state, the surface temperature Tsf of the friction material 33 when the lockup clutch 32 is released is estimated in SA2 corresponding to the surface temperature estimation means 112 (temperature release estimation means 114). Is done. When estimating the surface temperature Tsf, it is determined whether the vehicle is in a driving state or a driven state, and the surface temperature Tsf at the time of release shown in FIG. 7 according to the driving / driven state of the vehicle is estimated. The relationship map is read, and the temperature change amount α is obtained by linear interpolation from the relationship map, the current turbine rotation speed Nt, and the temperature difference ΔT (Tsfi-1−Toil). Based on the above-described equation (1), the current surface temperature Tsf (= Tsfi) of the friction material 33 is estimated (calculated). When the predetermined elapsed time ta1 has elapsed since the lock-up clutch 32 was released, the surface temperature Tsf of the friction material 33 is calculated based on the above-described equation (1 ').

  If it is determined in SA1 that the lockup clutch 32 is in the fully engaged state (L / U control), the lockup clutch 32 is detected in SA3 corresponding to the surface temperature estimating means 112 (engagement temperature estimating means 116). The surface temperature Tsf of the friction material 33 at the time of complete engagement is estimated. When estimating the surface temperature Tsf, it is determined whether the vehicle is in a driving state or a driven state, and the surface temperature Tsf at the time of full engagement shown in FIG. 8 according to the driving / driven state of the vehicle is estimated. The relationship map for reading is loaded. Then, the amount of temperature change β is obtained by linear interpolation from the relationship map, the current turbine rotational speed Nt, and the temperature difference ΔT. Further, the current surface temperature Tsf (= Tsfi) of the friction material 33 is estimated (calculated) from the obtained temperature change amount β based on the above-described equation (2). When the predetermined elapsed time tb1 has elapsed since the lockup clutch 32 is completely engaged, the surface temperature Tsf of the friction material 33 is calculated based on the above-described equation (2 ').

If it is determined in SA1 that the lockup clutch 32 is in the slip control state (FL / U control), the lockup slip 32 slip control is performed in SA4 corresponding to the surface temperature estimation means 112 (slip temperature estimation means 118). The surface temperature Tsf of the friction material 33 during (FL / U control) is estimated. In SA4, the lockup clutch transmission torque _TLC is calculated from the above-described equation (3), and the calorific value _QLC from the friction material 33 is calculated from the calculated lockup clutch transmission torque _TLC based on the equation (4). Calculated. The current surface temperature Tsf of the friction material 33 is estimated from the calculated calorific value Q _LC based on the above-described equation (5).

  In SA5 corresponding to the slip control prohibiting means 122, whether or not the surface temperature Tsf of the friction material 33 estimated by any one of SA2 to SA4 is equal to or higher than a first predetermined estimated temperature Tend that prohibits preset slip control. Is determined. When it is determined in SA5 that the surface temperature Tsf of the friction material 33 is equal to or higher than the first predetermined estimated surface temperature Tend, slip control of the lockup clutch 32 is prohibited or disabled in SA8 corresponding to the slip control prohibiting means 122. Is terminated. On the other hand, when the surface temperature Tsf of the friction material 33 is lower than the first predetermined estimated surface temperature Tend, whether or not the surface temperature Tsf of the friction material 33 is equal to or lower than the second predetermined estimated temperature Tsts in SA6 corresponding to the slip control permission means 124. Is determined. If SA6 is negative, that is, if the surface temperature Tsf of the friction material 33 exceeds the second predetermined estimated temperature Tsts, this routine is terminated. When SA6 is positive, that is, when the surface temperature Tsf of the friction material 33 is equal to or lower than the second predetermined estimated temperature Tsts, the lockup clutch in which slip control is prohibited by SA8 in SA7 corresponding to the slip control permission means 124. The prohibition of the slip control 32 is released and the execution of the slip control is permitted.

  As described above, according to the present embodiment, the surface temperature estimating means 112 determines the surface temperature Tsf of the friction material 33 of the lockup clutch 32 at the time of releasing the lockup clutch, at the time of slip control, and at the time of complete engagement. Since the lockup control means 112 controls the operation state of the lockup clutch 32 based on the surface temperature Tsf of the friction material 33 that is always estimated under each of the above conditions, In addition, the surface temperature Tsf of the friction material 33 is always estimated even when the lockup clutch 32 is released and fully engaged, and the optimum lockup control is performed based on the surface temperature Tsf of the friction material 33 that is always estimated. Is possible.

  Further, according to the present embodiment, when the surface temperature Tsf of the friction material 33 estimated by the surface temperature estimating means 112 becomes equal to or higher than the first predetermined estimated temperature Tend, the slip-up control of the lockup clutch 32 is prohibited, so that the lockup is performed. A decrease in durability of the friction material 33 of the clutch 32 is effectively suppressed.

  Further, according to the present embodiment, when slip control is prohibited, the surface temperature Tsf of the friction material 33 estimated by the surface temperature estimating means 112 is equal to or lower than a preset second predetermined estimated temperature Tsts. Since the prohibition of the slip control is released, the fuel efficiency improves as the slip control once prohibited is performed again.

  Further, according to this embodiment, when the temperature difference ΔT between the turbine rotational speed Nt and the previously estimated surface temperature Tsf of the friction material 33 and the ATF oil temperature Toil is detected, the current friction is determined based on the relationship map. The surface temperature Tsf of the material 33 can be accurately estimated.

  The relationship map is obtained in advance every time the lockup clutch 32 is completely engaged and released, and the relationship map used is switched according to the engagement state of the lockup clutch 32. The accuracy of the surface temperature Tsf 33 is further increased. The change characteristic of the surface temperature Tsf of the friction material 33 varies depending on the contact state between the friction material 33 of the lock-up clutch 32 and the hydraulic oil in the torque converter 30 when the lock-up clutch 32 is completely engaged and released. It has been confirmed that there is a difference between full engagement and disengagement. Therefore, the accuracy of the estimated surface temperature Tsf of the friction material 33 can be estimated by obtaining a relationship map in advance for each full engagement and release and switching to a relationship map corresponding to the engagement state of the lockup clutch 32. It gets even higher.

  Further, according to the present embodiment, the relationship map is obtained in advance every time the vehicle is driven and every time it is driven, and the relationship map used according to the driving state of the vehicle is switched. The accuracy of the surface temperature Tsf is further increased. As the flow of hydraulic oil in the torque converter 30 differs between when the vehicle is driven and when it is driven, it is confirmed that the change characteristic of the surface temperature Tsf of the friction material 33 differs between when it is driven and when it is driven. Has been. Therefore, the accuracy of the estimated surface temperature Tsf of the friction material 33 is further increased by obtaining a relationship map in advance for each driving and driving of the vehicle and switching to the relationship map according to the driving state of the vehicle. .

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, the automatic transmission 10 of the above-described embodiment is an automatic transmission having six forward speeds and one reverse speed, but the number of shift stages and the internal structure of the automatic transmission are not particularly limited to the present embodiment, and may be changed as appropriate. It doesn't matter. The automatic transmission 10 is not limited to a stepped automatic transmission, and may be a continuously variable transmission such as a belt-type continuously variable transmission. That is, the present invention can be appropriately applied to any vehicle power transmission device that includes a torque converter having a lock-up clutch.

  In the above-described embodiment, the lock-up clutch 32 is provided in the torque converter 30. However, the lock-up clutch 32 is not necessarily limited to the torque converter, and may be provided in a fluid clutch that does not have a torque amplification function. Absent.

  In the above-described embodiment, the hydraulic control circuit 40 is not necessarily limited to the above-described oil passage configuration even if it is an example. The present invention can be appropriately applied as long as the slip control of the lockup clutch 32 can be performed.

  In the above-described embodiment, the first predetermined estimated temperature Tend and the second predetermined estimated temperature Tsts are different from each other. However, the first predetermined estimated temperature Tend and the second predetermined estimated temperature are not necessarily limited to different numerical values. Tsts may be the same.

  In the above-described embodiment, the surface temperature Tsf of the friction material 33 at the time of slip control is estimated based on the equations (3) to (5). However, the surface temperature Tsf of the friction material 33 at the time of slip control is estimated. Is an example, for example, the oil temperature of the hydraulic oil in the torque converter 30 is detected, and the temperature difference between the detected oil temperature and the previously estimated surface temperature of the friction material 33 is experimentally obtained. The surface temperature may be estimated by other methods such as estimating the surface temperature by multiplying by a corrected integer.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

8: Vehicle power transmission device 28: Engine 30: Torque converter (fluid transmission device)
32: Lock-up clutch 33: Friction material 34: Electronic control device (control device)
109: Lockup control means 112: Surface temperature estimation means Tsf: Surface temperature of friction material Tsfi: Surface temperature estimated this time Tsfi-1: Surface temperature estimated last time Tend: First predetermined estimated temperature Tsts: Second predetermined estimation Temperature Nt: Turbine rotation speed Toil: ATF oil temperature (hydraulic oil temperature)
ΔT: temperature difference

Claims (6)

In a vehicle equipped with a fluid transmission device having a lock-up clutch on the output side of the engine, a control device for a vehicle lock-up clutch comprising lock-up control means for controlling the operating state of the lock-up clutch,
A surface temperature estimating means for constantly estimating the surface temperature of the friction material of the lockup clutch under the respective circumstances at the time of releasing the lockup clutch, at the time of slip control, and at the time of complete engagement;
The lockup control means for controlling the lockup clutch for a vehicle, wherein the lockup control means controls the operating state of the lockup clutch based on the surface temperature of the friction material always estimated by the surface temperature estimation means. .   The lockup control means prohibits slip control of the lockup clutch when the surface temperature of the friction material estimated by the surface temperature estimation means is equal to or higher than a first predetermined estimated temperature set in advance. The control device for a lockup clutch for a vehicle according to claim 1.   When the slip control is prohibited, when the surface temperature of the friction material estimated by the surface temperature estimation means becomes equal to or lower than a second predetermined estimated temperature set in advance, the lockup control means 3. The vehicle lockup clutch control device according to claim 2, wherein the prohibition is canceled.   The surface temperature estimating means comprises the friction material comprising a turbine rotational speed obtained in advance and a temperature difference between the surface temperature of the friction material and the hydraulic oil temperature when the lockup clutch is completely engaged and released. The current surface temperature of the friction material is estimated based on the current turbine rotation speed and the temperature difference from the relationship map of the surface temperature change amount of A control device for a lockup clutch for a vehicle.   The relation map is obtained in advance every time the lockup clutch is completely engaged and released, and the relation map used according to the engagement state of the lockup clutch is switched. 4 is a control device for a vehicle lock-up clutch.   6. The vehicle lock according to claim 4 or 5, wherein the relationship map is obtained in advance every time the vehicle is driven and every time it is driven, and the relationship map used is switched according to the driving state of the vehicle. Up clutch control device.

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