WO2012105016A1 - Control device for vehicular power transmission device - Google Patents

Abstract

Provided is a control device for a vehicular power transmission device, which may improve fuel efficiency by reducing engine load during neutral control. During implementation of the neutral control, parking-state lockup clutch engagement control is implemented to generate an engagement force at a lockup clutch (46). Accordingly, during the implementation of the neutral control, a turbine rotation speed (NT) is increased by the engagement force of the lockup clutch (46) and a rotation speed of an input side (engine side) of a clutch (C1) is increased at the same time, through which first differential clutch rotation (ΔN_C1) becomes larger compared with when the lockup clutch (46) is released, and a drag torque (TD_C1) of the clutch (C1) is reduced. As a result, engine load of an engine (10) remaining in an idling state during the neutral control is reduced and fuel efficiency of a vehicle (6) is improved.

Description

Control device for vehicle power transmission device

The present invention relates to a control device for a vehicle power transmission device having a neutral control function, and more particularly to a technique for improving the fuel efficiency of a vehicle.

In a vehicle power transmission device including a fluid transmission device that transmits engine power to drive wheels, power transmission between the output member of the fluid transmission device and the drive wheels during vehicle stop is performed in order to improve fuel consumption. It is well known that neutral control is executed to block or suppress the above. By executing the neutral control, the engine load of the engine that is idling while the vehicle is stopped is reduced, and the fuel efficiency of the vehicle is improved. For example, as a control device that executes the neutral control, the control device for a vehicle power transmission device of Patent Document 1 can be cited. The control device of Patent Document 1 basically executes the neutral control when a predetermined neutral control condition is satisfied. However, in order to ensure the performance of the heater that is an air conditioner, the heater is in an on state. When the outside air temperature is equal to or lower than the predetermined temperature and the engine water temperature is equal to or lower than the predetermined temperature, the neutral control is not executed.

JP 2006-63990 A JP 2002-39348 A

The neutral control executed by the control device for a vehicle power transmission device disclosed in Patent Document 1 is such that, while the vehicle is stopped in the D range, the engine clutch is reduced by bringing the starting clutch in the transmission close to the released state, that is, the neutral state, and the vehicle is stopped. It is intended to improve the fuel efficiency. However, even when the starting clutch is in a released state or a state close thereto in the neutral control, the shear resistance generated between the friction materials of the starting clutch is not completely zero. Torque capacity corresponding to The shear resistance acts to reduce the speed ratio of the fluid transmission device and increase the capacity coefficient of the fluid transmission device, so that the engine load during the neutral control is increased. Therefore, if the shear resistance is generated in the starting clutch during the neutral control, the shear resistance increases the engine load, resulting in a poor fuel consumption. Further, the lower the hydraulic oil temperature of the starting clutch, the greater the shear resistance in the released state of the starting clutch, and the engine load tends to increase. On the other hand, the shear resistance of the starting clutch tends to decrease as the rotational speed difference between the friction materials of the starting clutch increases.

The present invention has been made against the background of the above circumstances, and the object of the present invention is to control a vehicle power transmission device that can improve fuel efficiency by reducing the engine load during the neutral control. To provide an apparatus.

In order to achieve the above object, the gist of the present invention is that: (a) a lockup clutch that mechanically directly connects between input and output members of a fluid transmission device that transmits engine power to drive wheels; A power transmission device for a vehicle comprising a power interrupting device for interrupting power transmission between an output member of a fluid transmission device and the drive wheel, wherein the power interrupting device is set to a neutral state in a slipping state or a releasing state when the vehicle is stopped. A control device for a vehicle power transmission device that executes control, wherein (b) an engagement force is generated in the lock-up clutch during execution of the neutral control.

In this way, during the execution of the neutral control (during the neutral control), the rotational speed of the output member of the fluid transmission device is increased by the engagement force of the lockup clutch and the input side (engine) of the power interrupting device The rotation speed of the power interrupting device is also increased, thereby increasing the rotational speed difference between the input rotating element and the output rotating element of the power interrupting device, and the input rotating element and output side of the power interrupting device. The shear resistance generated between the rotating elements is reduced. That is, the drag torque of the power interrupting device due to the shear resistance decreases. As a result, the engine load during the neutral control is reduced, and the fuel efficiency of the vehicle can be improved.

It should be noted that in stopping lock-up clutch engagement control in which engagement force is generated in the lock-up clutch during execution of the neutral control, it is only necessary to generate engagement force in the lock-up clutch. It is not necessary to be in an engaged state, and a slip state may be used. In the neutral control, power transmission between the output member and the driving wheel is suppressed, but suppression of power transmission includes interruption of power transmission. Further, for example, the fuel consumption is a travel distance per unit fuel consumption, and the improvement in fuel consumption is an increase in the travel distance per unit fuel consumption, or the fuel consumption rate ( = Fuel consumption / drive wheel output) is reduced. Conversely, a reduction in fuel consumption means that the travel distance per unit fuel consumption is shortened, or the fuel consumption rate of the entire vehicle is increased.

Here, preferably, the lower the hydraulic oil temperature of the vehicular power transmission device, the greater the number of execution opportunities for the control that generates the engagement force in the lock-up clutch during the execution of the neutral control. In this way, the drag torque of the power interrupting device is likely to be greater at low temperatures than at high temperatures, so that the advantage of improved fuel efficiency by the lockup clutch engagement control during stopping is effectively obtained. It is possible.

Preferably, when the engagement force is generated in the lockup clutch during the execution of the neutral control, the engagement force of the lockup clutch is reduced as the hydraulic oil temperature of the vehicle power transmission device is higher. To do. In this way, the influence of the engagement of the lock-up clutch on the responsiveness at the time of return from the neutral control can be suppressed at high temperatures when the responsiveness of the power interrupting device is good. On the other hand, since the responsiveness of the power interrupting device is originally not good at low temperatures, the engagement of the lockup clutch hardly affects the responsiveness at the time of return from the neutral control, and the lockup clutch engagement control during stopping It is possible to obtain a sufficient fuel efficiency improvement effect.

Preferably, when an engagement force is generated in the lock-up clutch during the neutral control, after the transient operation in the release direction of the power interrupting device in the neutral control is completed, Begins to generate an engagement force in the lockup clutch. In this case, the engine load temporarily varies when the engagement force is generated in the lockup clutch as compared with the case where the engagement force is generated in the lockup clutch before the release operation of the power interrupting device. The width can be suppressed, and deterioration in fuel consumption due to temporary fluctuations in the engine load can be suppressed.

Preferably, when the engagement force is generated in the lockup clutch during the execution of the neutral control, the engagement force of the lockup clutch is reduced as the engine speed increases. Here, during the neutral control, the rotational speed difference between the input-side rotating element and the output-side rotating element of the power interrupting device increases as the engine speed increases, and the drag torque of the power interrupting device increases. Tend to decline. Accordingly, in this way, by reducing the engagement force of the lockup clutch in consideration of the rotation speed of the engine, the fuel efficiency improvement effect of the lockup clutch engagement control during stopping is not reduced, It is possible to improve the responsiveness of releasing the lockup clutch when the lockup clutch engagement control during stop is finished.

Also preferably, the power interrupting device is a wet friction clutch. In this case, the wet friction clutch is generally used as the power interrupting device in many cases, so that the present invention can be widely applied to specific vehicles.

Also preferably, the lock-up clutch is released at the end of the neutral control.

Also preferably, at the end of the neutral control, the power interrupting device is fully engaged after the lockup clutch is released.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a skeleton diagram illustrating a configuration of a vehicle drive device to which the present invention is preferably applied. FIG. 2 is an operation table for explaining an operation state of engagement elements when a plurality of shift stages (gear stages) are established in the automatic transmission included in the vehicle drive device of FIG. 1. When the clutch C1 included in the automatic transmission of FIG. 1 is released, a first clutch differential rotation, which is a rotational speed difference between the input side friction material and the output side friction material of the clutch C1, and the clutch C1. It is the figure which showed the relationship with the drag torque of this according to the oil temperature of the hydraulic fluid supplied to the clutch C1. FIG. 2 is a diagram illustrating a relationship between a capacity coefficient and a speed ratio of a torque converter included in the vehicle drive device of FIG. 1. A limit speed ratio that is a speed ratio of the torque converter when the shift range of the automatic transmission included in the vehicle drive device of FIG. 1 is the neutral range (N range), that is, when the automatic transmission is in the neutral state, It is the figure which showed the relationship with the input rotational speed of a torque converter according to the hydraulic oil temperature of the clutch C1. FIG. 2 is a diagram illustrating various signals input to an electronic control device that controls the vehicle drive device of FIG. 1, and a functional block diagram for explaining a main part of a control function provided in the electronic control device. is there. 7 is a time chart for explaining the operation timing of the clutch C1 and the lockup clutch in the neutral control and the lockup clutch engagement control during stopping executed in parallel with each other by the electronic control unit of FIG. In the stop-up lockup clutch engagement control executed by the electronic control device of FIG. 6, the lockup differential pressure that generates the engagement force in the lockup clutch and the hydraulic oil temperature of the automatic transmission, that is, the hydraulic oil temperature of the clutch C1. It is a figure showing an example of the relationship. FIG. 7 is a diagram illustrating an example of a relationship between a lockup differential pressure that causes an engagement force to be generated in the lockup clutch and an engine rotation speed in the lockup clutch engagement control that is executed by the electronic control device of FIG. 6. FIG. 7 is a flowchart for explaining a first main part of the control operation of the electronic control device of FIG. 6, that is, a control operation for executing neutral control and switching a control execution flag. FIG. 7 is a flowchart for explaining a second main part of the control operation of the electronic control unit of FIG. 6, that is, a control operation for executing lock-up clutch engagement control during stopping in parallel with neutral control.

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

FIG. 1 is a skeleton diagram illustrating a configuration of a vehicle drive device 8 (hereinafter referred to as “drive device 8”) to which the present invention is preferably applied. The drive device 8 includes a vehicle power transmission device 9 and an engine 10. The vehicle power transmission device 9 is connected to the automatic transmission 12 and the output shaft 13 of the engine 10 in a transmission case 30 that is a non-rotating member, and is interposed between the engine 10 and the automatic transmission 12. Torque converter 14 is provided. And the drive device 8 is used suitably for FF vehicle mounted in the left-right direction (horizontal placement) of the vehicle 6 (refer FIG. 6).

The automatic transmission 12 constitutes a part of a power transmission path between the torque converter 14 and the drive wheels 38 (see FIG. 6), and an output torque TE (hereinafter referred to as “engine torque TE”) of the engine 10 is input. Transmission. The automatic transmission 12 includes a plurality of hydraulic friction engagement devices (clutch C, brake B), specifically five hydraulic friction engagement devices, and one of the plurality of hydraulic friction engagement devices. This is a transmission in which a plurality of shift stages (gear stages) are selectively established by re-holding. In short, it is a stepped transmission that performs a so-called clutch-to-clutch shift that is often used in general vehicles. The automatic transmission 12 includes a first transmission unit 18 mainly composed of a single pinion type first planetary gear unit 16, a double pinion type second planetary gear unit 20, and a single pinion type third planetary gear unit. A second transmission unit 24 having a Ravigneaux type configuration with the device 22 as a main body is provided on a coaxial line, and the rotation of the input shaft 26 is shifted and output from the transmission output rotation member 28. The input shaft 26 is a turbine shaft of the torque converter 14 that is rotationally driven by the engine 10 that is an internal combustion engine that supplies power for traveling in this embodiment. The transmission output rotating member 28 functions as an output gear, that is, a differential drive gear that meshes with a differential driven gear (large-diameter gear) 34 in order to transmit power to the differential gear device 32 (see FIG. 6). . The output of the engine 10 is transmitted to a pair of drive wheels (front wheels) 38 via the torque converter 14, the automatic transmission 12, the differential gear device 32, and a pair of axles 36 (FIG. 6). reference). Accordingly, the higher the output rotation speed Nout (rpm) of the automatic transmission 12 that is the rotation speed of the transmission output rotation member 28, the higher the vehicle speed V (km / h). Correspond with. The automatic transmission 12 is substantially symmetrical with respect to the center line, and the lower half of the center line is omitted in FIG.

FIG. 2 is an operation table for explaining the operation states of the engagement elements when a plurality of shift stages (gear stages) are established in the automatic transmission 12. The automatic transmission 12 corresponds to the combination of any one of the rotational states (sun gears S1 to S3, carriers CA1 to CA3, ring gears R1 to R3) of the first transmission unit 18 and the second transmission unit 24. Six forward shift stages from the first shift stage “1st” to the sixth shift stage “6th” are 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, (1) the first speed gear stage is established by the engagement of the clutch C1 and the brake B2, and (2) the second speed gear stage is established by the engagement of the clutch C1 and the brake B1. (3) The third gear is set by engagement of the clutch C1 and the brake B3, (4) The fourth gear is set by engagement of the clutch C1 and the clutch C2, and (5) The engagement of the clutch C2 and the brake B3. Thus, the fifth gear is established, and (6) the sixth gear is established by engagement of the clutch C2 and the brake B1. Further, the reverse gear is established by the engagement of the brake B2 and the brake B3, and the automatic transmission 12 is basically set to the neutral state by releasing any of the clutches C1, C2, and the brakes B1 to B3. It is configured. For example, when the forward travel range such as the D range is selected and the vehicle 6 is stopped, the first shift stage “1st” that is the shift stage on the lowest vehicle speed side is basically established. In the automatic transmission 12 of the present embodiment, a pair of hydraulic friction engagement devices are engaged in order to achieve a predetermined gear stage, and one of the pair of hydraulic friction engagement devices is When released, the predetermined gear stage is not established, and the power transmission path in the automatic transmission 12 is released to enter a neutral state.

The operation table in FIG. 2 summarizes the relationship between the above-mentioned shift speeds and the operation states of the clutches C1, C2 and the brakes B1 to B3. Represents the event. Since the one-way clutch F1 is provided in parallel to the brake B2 that establishes the first shift stage “1st”, it is not always necessary to engage the brake B2 at the time of start (acceleration). Further, the gear ratios of the respective gear stages are the gear ratios of the first planetary gear device 16, the second planetary gear device 20, and the third planetary gear device 22 (= number of teeth of the sun gear / number of teeth of the ring gear) ρ1, ρ2. , Ρ3 as appropriate.

The clutches C1 and C2 and the brakes B1 to B3 (hereinafter simply referred to as the clutch C and the brake B unless otherwise distinguished) are hydraulic friction members that are engaged and controlled by a hydraulic actuator such as a wet multi-plate clutch or a brake. Engagement and de-energization and current control of the linear solenoid valve provided in the hydraulic control circuit 40 (see FIG. 1) can be switched between engaged and disengaged states, as well as transient oil pressure during engagement and disengagement. Is controlled.

As shown in FIG. 2, the clutch C1 and the clutch C2 are always engaged with each other at any one of the forward gears. That is, the engagement of the clutch C1 or the clutch C2 is a requirement for achieving the forward gear stage. Therefore, in the present embodiment, the clutch C1 or the clutch C2 corresponds to a forward clutch (forward clutch). In this embodiment, so-called neutral control (hereinafter sometimes abbreviated as “N control”) is executed, and the present invention relates to the neutral control. In this embodiment, Unless otherwise specified, the forward clutch (forward clutch) refers to the clutch C1. When the forward travel range is selected while the vehicle is stopped, the first shift stage “1st” of the automatic transmission 12 is established except when the neutral control is being executed. It functions as a clutch that selectively cuts off power transmission between the turbine impeller 14b of the torque converter 14 and the drive wheel 38, and corresponds to the power interrupting device of the present invention.

FIG. 3 shows a rotational speed difference ΔN _C1 between the input friction material and the output friction material of the clutch C1, that is, a differential rotation ΔN _C1 of the clutch _C1 (hereinafter referred to as a first clutch difference) when the clutch C1 is released. a) that the rotational .DELTA.N _C1, the relationship between the drag torque TD _C1 of the clutch C1, the temporal changes being shown according to the temperature (hydraulic fluid temperature) TEMP _oIL of the hydraulic fluid supplied to the clutch C1. The drag torque TD _C1 of the clutch C1, in the disengaged state with one of the friction member and the other friction material relative rotation is not in direct contact, is transmitted from the one of the friction material to the other of the friction material Drag torque. In a wet multi-plate friction clutch such as the clutch C1, hydraulic oil is interposed between the friction materials in the non-engaged state, and the drag torque is generated by the viscosity of the hydraulic oil. As shown in FIG. 3, the drag torque TD _C1 of the clutch C1 increases as the hydraulic oil temperature TEMP _OIL decreases. This is because the lower the hydraulic oil temperature TEMP _{OIL, the} higher the viscosity of the hydraulic oil. Further, the drag torque TD _C1 of the clutch _C1 decreases as the first clutch differential rotation ΔN _C1 increases. This is because the larger the first clutch differential rotation ΔN _C1 is, the more the hydraulic oil is stirred between the friction materials, and the influence of the hydraulic oil viscosity on the drag torque TD _C1 is reduced. The clutch C1 is a wet multi-plate friction clutch generally used in a vehicle automatic transmission, and the characteristics shown in FIG. 3 are common to general wet multi-plate friction clutches. Further, the hydraulic oil of the clutch C1 is the hydraulic oil of the automatic transmission 12. For example, the hydraulic oil lubricates rotating members such as gears and bearings included in the automatic transmission 12, and the automatic transmission 12 includes the hydraulic oil. The clutch C and the brake B are supplied from the hydraulic control circuit 40 and are also supplied to the torque converter 14.

Returning to FIG. 1, as shown in FIG. 1, the engine 10 is driven to open and close by the throttle actuator 42 based on the electric signal from the throttle actuator 42 and the electronic control unit 52 in the intake pipe that intakes the engine 10. The electronic throttle valve 44 is provided. The electronic throttle valve 44 is an intake air amount control valve for adjusting the engine torque TE by adjusting the intake air amount Q of the engine 10 while the engine is being driven. The engine torque TE increases as the "throttle opening TAP" increases. Therefore, the engine torque TE corresponds to the throttle opening TAP. Basically, based on a predetermined relationship, the throttle opening Acc (%), which is the operation amount (depression amount) of the accelerator pedal 48 corresponding to the driver's output request amount, is larger. The opening degree TAP (%) is increased.

The torque converter 14 transmits the driving force generated by the engine 10 to the automatic transmission 12 via the fluid. That is, the torque converter 14 is a fluid transmission device that transmits the power of the engine 10 to the drive wheels 38 via a fluid. The torque converter 14 includes a pump impeller 14a connected to an output shaft (crankshaft) 13 of the engine 10, a turbine impeller 14b connected to an input shaft 26 of the automatic transmission 12, and a one-way clutch. And a stator impeller 14 c connected to a housing (transmission case) 30 of the automatic transmission 12. With such a configuration, the pump impeller 14a is equivalent to an input member of the torque converter 14 because the power of the engine 10 is input, and the turbine impeller 14b outputs the power toward the drive wheels 38, so the torque converter 14 Corresponds to the output member. The torque converter 14 includes a lockup clutch 46 that is a direct coupling clutch that mechanically directly connects the pump impeller 14a and the turbine impeller 14b between the pump impeller 14a and the turbine impeller 14b. The lock-up clutch 46 is brought into a fully engaged state, a slip state, or a released state by hydraulic control or the like, and in short, selectively connects the pump impeller 14a and the turbine impeller 14b directly. When the lock-up clutch 46 is brought into a completely engaged state, the pump impeller 14a and the turbine impeller 14b are mechanically directly connected and integrally rotated. That is, the crankshaft 13 of the engine 10 and the input shaft 26 of the automatic transmission 12 are rotated together.

FIG. 4 is a diagram showing the relationship between the capacity coefficient C of the torque converter 14 and the speed ratio e. The speed ratio e of the torque converter 14 is a ratio (e = NT / NP) of the turbine rotational speed NT that is the rotational speed NT of the turbine impeller 14b to the pump rotational speed NP that is the rotational speed NP of the pump impeller 14a. . Further, the capacity coefficient C of the torque converter 14 is calculated as “C = Tp / NP ² ” when the torque of the pump impeller 14a is Tp, and therefore, at the same pump rotational speed NP (= engine rotational speed NE). In comparison, it can be said that the larger the capacity coefficient C, the greater the engine load. In the relationship shown in FIG. 4, as a general trend, the capacity coefficient C of the torque converter 14 decreases as the speed ratio e increases. The capacity coefficient C becomes zero when the speed ratio e is 1. Therefore, the neutral control executed by the electronic control unit 52 is intended to improve the fuel consumption by reducing the engine load while the vehicle is stopped. Therefore, the speed ratio e of the torque converter 14 is close to 1 during the neutral control. It is desirable that the capacity coefficient C becomes smaller. The torque converter 14 of the present embodiment is a general torque converter connected to a vehicle automatic transmission, and the characteristics shown in FIG. 4 are generally common to vehicle torque converters. Further, in the characteristics shown in FIG. 4, the lockup clutch 46 is always completely released.

FIG. 5 shows the limit speed ratio e0, which is the speed ratio e of the torque converter 14 when the shift range of the automatic transmission 12 is the neutral range (N range), that is, when the automatic transmission 12 is in the neutral state. 14 is a diagram showing a relationship with the input rotational speed Ntcin of 14 according to the hydraulic oil temperature TEMP _OIL of the clutch C1. As is apparent from the skeleton diagram of FIG. 1, the input rotational speed Ntcin of the torque converter 14 is the pump rotational speed NP and is the same as the engine rotational speed NE (Ntcin = NP = NE). As shown in FIG. 5, the relationship between the input rotation speed Ntcin and the limit speed ratio e0 tends to be smaller as the input rotation speed Ntcin is lower, and this tendency is further related to the hydraulic oil temperature TEMP _OIL. The lower the value, the more prominent. This is considered because the drag torque TD _C1 of the clutch C1 increases as the hydraulic oil temperature TEMP _OIL decreases and increases as the first clutch differential rotation ΔN _C1 decreases, as described in FIG. . In addition, if the speed limit ratio e0 significantly decreases in FIG. 5, the capacity coefficient C at the time of releasing the clutch C1 increases as the speed limit ratio e0 decreases as shown in FIG. 4, and the engine load at that time increases. To do. Therefore, according to the relationship shown in FIG. 5, when the engine 10 is idling, for example, when the vehicle is stopped, the engine 10 is rotating in a low rotation speed range as indicated by the arrow AR01 range of FIG. Therefore, if the hydraulic oil temperature TEMP _OIL is low, even if the automatic transmission 12 is set to the neutral state, the speed ratio e0 of the torque converter 14 does not increase so much and the engine load does not decrease so much. Since the electronic control unit 52 of this embodiment controls the engagement of the lockup clutch 46 so that the engine load can be reduced during the neutral control based on the characteristics of the torque converter 14 and the clutch C1. This will be described later with reference to FIGS. Although the characteristics shown in FIG. 5 are unknown, they are common in a vehicle in which a general torque converter and an automatic transmission including a clutch and the like are connected in series from the engine side. Further, in the characteristics shown in FIG. 5, the lockup clutch 46 is always completely released.

FIG. 6 is a diagram illustrating various signals input to the electronic control device 52 and a functional block diagram for explaining a main part of a control function provided in the electronic control device 52. The electronic control device 52 has a function as a control device of the driving device 8, and is a so-called microcomputer including, for example, a ROM, a RAM, a CPU, an input / output interface, etc., and the CPU has a temporary storage function of the RAM. The input signal is processed according to a program stored in advance in the ROM while being used, and automatic shift control for controlling the linear solenoid valve of the hydraulic control circuit 40, output control of the engine 10, neutral control, and the like are executed.

The neutral control means that the clutch C1 is brought into a slip state or a disengaged state when a neutral control condition set in advance to reduce the engine load while the vehicle is stopped (stopped) and to improve fuel efficiency is satisfied. In this control, power transmission between the turbine impeller 14b of the torque converter 14 and the drive wheels 38 is suppressed.

As shown in FIG. 6, the electronic control unit 52 represents a signal indicating the accelerator opening Acc from the accelerator opening sensor 56, a foot brake operation for depressing the foot brake pedal 60 from the foot brake switch 58, that is, a brake on. A signal, a signal from the shift position sensor 64 representing the shift position _PSH of the shift operating device 62 operated by the driver to switch the traveling range, a signal representing the engine water temperature TEMP _W from the engine water temperature sensor 66, a hydraulic oil temperature sensor 68, the signal representing the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 from 68, the signal from the engine speed sensor 70 representing the engine speed NE, which is the speed of the engine 10, and the turbine speed NT from the turbine speed sensor 72. , An output rotational speed Nout of the automatic transmission 12 from the vehicle speed sensor 74 Such as a signal representative of the response to the vehicle speed V is supplied. Note that the hydraulic oil of the automatic transmission 12 is also used in the torque converter 14 in common, so it can be said that it is the hydraulic oil of the vehicle power transmission device 9. Therefore, the hydraulic oil temperature TEMP _OIL detected by the hydraulic oil temperature sensor 68 is a hydraulic oil temperature TEMP _OIL such clutch C1 included in the automatic transmission 12, in other words, the working oil temperature of the vehicle power transmission device 9 TEMP _OIL .

As shown in FIG. 6, the electronic control unit 52 includes a neutral control condition determination unit 80 as a neutral control condition determination unit, a neutral control execution unit 82 as a neutral control execution unit, and a control execution as a control execution flag switching unit. It includes a flag switching means 84, a control execution flag determining means 86 as a control execution flag determining section, and a stopping lockup clutch engaging control means 88 as a stopping lockup clutch engagement control section.

The neutral control condition determining means 80 sequentially determines whether or not the neutral control condition is satisfied, that is, whether or not the neutral control condition is satisfied. For example, the neutral control condition is (a) the forward travel range is selected by setting the shift position P _SH of the shift operation device 62 for operating the shift range of the automatic transmission 12 to the D position or the like. (B) The vehicle is stopped, that is, the vehicle speed V is zero, (c) the accelerator opening Acc is zero, and (d) the vehicle 6 is being braked by the foot brake operation. (E) The fluctuation range of the engine rotation speed NE while the vehicle is stopped is within a predetermined range and is stable. In the determination of whether or not the vehicle is stopped, which is the condition (b), for example, if the vehicle speed sensor 74 does not start a vehicle speed pulse within a predetermined determination time, it is determined that the vehicle is stopped. In the condition (e), when the engine water temperature TEMP _W is extremely low, the fluctuation range of the engine rotation speed NE may be increased due to a change in engine friction or the like. It is provided to prevent neutral control.

The neutral control condition determining means 80 determines that the neutral control condition is satisfied when all of the above conditions (a) to (e) are satisfied. On the other hand, the neutral control condition determining means 80 determines that the neutral control condition is not satisfied when any one of the conditions (a) to (e) is not satisfied. The neutral control conditions shown in the above (a) to (e) are only examples, and are not limited to them. Some of the conditions may be changed or deleted, and other conditions may be added. It does not matter if it is done.

When the neutral control condition determining unit 80 determines that the neutral control condition is satisfied, the neutral control executing unit 82 executes the neutral control, while the neutral control condition is determined to be satisfied. The neutral control is continued. When the neutral control condition determining unit 80 determines that the neutral control condition is not established, for example, when the neutral control condition is switched from established to not established, the neutral control executing unit 82 performs the neutral control. finish. Specifically, to end the neutral control that has been executed is to completely engage the clutch C1 that has been in the slipping state or the releasing state.

The control execution flag switching means 84 is a lockup clutch engagement control execution flag FLG1act (hereinafter abbreviated as control execution flag FLG1act) that indicates whether or not a lockup clutch engagement control to be described later should be executed. Is switched based on the success or failure of the neutral control condition and the hydraulic oil temperature TEMP _OIL of the automatic transmission 12. If the control execution flag FLG1act is ON (ON), it indicates that the lockup clutch engagement control is to be executed while the vehicle is stopped. If the control execution flag FLG1act is OFF (OFF), the vehicle is stopped. It indicates that lockup clutch engagement control should not be executed.

Specifically, the control execution flag switching means 84 sets the control execution flag FLG1act so that the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 is higher than a predetermined oil temperature lower limit TEMP1 _OIL and the hydraulic oil temperature thereof. It is sequentially determined whether or not TEMP _OIL is lower than a predetermined oil temperature upper limit TEMP2 _OIL . The oil temperature lower limit value TEMP1 _OIL is a threshold value that the below-mentioned stop lock-up clutch engagement control is not executed at a hydraulic oil temperature TEMP _OIL below this value, and the hydraulic pressure responsiveness of the lock-up clutch 46 and the like. It is experimentally set in advance in consideration of the market requirements. For example, it is set to about −20 ° C. or −5 ° C. which is the minimum temperature of the hydraulic oil temperature TEMP _OIL under practical use of the vehicle 6. Has been. The oil temperature upper limit TEMP2 _OIL is a threshold that does not run any more hydraulic oil temperature TEMP _OIL in the stationary-state lockup clutch engagement control, the neutral control in long more of the hydraulic fluid in temperature TEMP _OIL Even if the lock-up clutch 46 is released, the speed ratio e of the torque converter 14 is sufficiently high so that the engine load can be sufficiently reduced, for example, set to about 20 ° C. in advance. Yes. In addition, the fuel efficiency improvement effect by the lockup clutch engagement control during stopping tends to become higher as the hydraulic oil temperature TEMP _OIL is lower, so the hydraulic oil temperature range from the oil temperature lower limit value TEMP1 _OIL to the oil temperature upper limit value TEMP2 _OIL Is provided close to the low temperature side in the change range of the hydraulic oil temperature TEMP _OIL from the time when the automatic transmission 12 is cold to the time when the warm-up is completed.

The control execution flag switching means 84 is when the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 is higher than the oil temperature lower limit value TEMP1 _OIL and the hydraulic oil temperature TEMP _OIL is lower than the oil temperature upper limit value TEMP2 _OIL. When the neutral control condition determining means 80 determines that the neutral control condition is satisfied, the control execution flag FLG1act is set to ON. On the other hand, when the hydraulic oil temperature TEMP _OIL is equal to or lower than the oil temperature lower limit value TEMP1 _OIL , the hydraulic control temperature flag TEMP _OIL is equal to or higher than the oil temperature upper limit value TEMP2 _OIL. When it is determined that the neutral control condition is not satisfied, the control execution flag FLG1act is set to OFF. Note that the oil temperature lower limit value TEMP1 _OIL is a determination value that is provided in consideration of market demands, and therefore, the oil temperature lower limit value TEMP1 _OIL may not be set, that is, the control execution flag switching means 84 may be set. May set the control execution flag FLG1act without determining the oil temperature lower limit value TEMP1 _OIL .

The control execution flag determination means 86 sequentially determines the set state of the control execution flag FLG1act. That is, it is sequentially determined whether the control execution flag FLG1act is ON or OFF.

When the control execution flag FLG1act is ON, the stop lock-up clutch engagement control means 88 generates a lock-up clutch engagement control during stop so as to generate an engagement force in the lock-up clutch 46 during the neutral control. Execute. That is, if the lockup clutch engagement control during stop is executed, it is executed in parallel with the neutral control. Whether or not the control execution flag FLG1act is ON is based on the determination of the control execution flag determination means 86. For example, when the vehicle is stopped, the lockup clutch engagement control means 88 generates an engagement force on the lockup clutch 46 so that the lockup clutch 46 is completely engaged in the vehicle lockup clutch engagement control. As a result, the pump impeller 14a and the turbine impeller 14b of the torque converter 14 rotate integrally, and the turbine rotational speed NT (= the rotational speed N _IN of the input shaft 26) is increased to the engine rotational speed NE. first clutch differential rotation .DELTA.N _C1 becomes larger than when 46 release.

Further, the stop lock-up clutch engagement control means 88 continues to execute the stop lock-up clutch engagement control while the control execution flag FLG1act is ON. On the other hand, when the control execution flag FLG1act is switched from ON to OFF, the lockup clutch 46 is released and the stopping lockup clutch engagement control is ended.

FIG. 7 is a time chart for explaining the operation timing of the clutch C1 and the lockup clutch 46 in the neutral control and the locked lockup clutch engagement control executed in parallel with each other. Specifically, FIG. 7 shows a first clutch engagement oil pressure P _C1 (hereinafter simply referred to as “C1 oil pressure”) that engages the engine rotation speed NE, the turbine rotation speed NT, and the clutch C1 from the start to the end of the neutral control. P _C1 ”), a lock-up differential pressure P _LU that is a hydraulic pressure for engaging the lock-up clutch 46, and a lock-up control linear solenoid valve SLU included in the hydraulic control circuit 40 controls the lock-up differential pressure P _LU . The time chart of the lockup control linear solenoid output pressure P _SLU (hereinafter simply referred to as “lockup clutch command hydraulic pressure P _SLU ”), which is the command hydraulic pressure to be output, is shown. The C1 oil pressure P _C1 shown in FIG. 7 corresponds to the engaging force of the clutch C1, and the higher the C1 oil pressure P _C1 is, the larger the engaging force of the clutch C1 is. The lock-up differential pressure P _LU corresponds to the engagement force of the lock-up clutch 46, the engagement force of the lock-up differential pressure P _LU lockup clutch 46 is zero or less is a zero, the lock-up differential pressure P _The larger the _LU , the greater the engagement force of the lockup clutch 46.

In FIG. 7, before the time t1, the neutral control condition is already satisfied, and the control execution flag FLG1act is switched to ON. Therefore, as can be seen from the time chart of the C1 oil pressure P _C1 , the neutral control execution means 82 starts the neutral control from the time point t1, and specifically, the clutch C1 that has been fully engaged is released from the time point t1. Being started. At time t2, the transitional operation in the release direction of the clutch C1 in the neutral control, that is, the release operation started from the time t1 of the clutch C1 is completed. Therefore, at time t2, the first clutch release determination (C1 release determination) that determines that the transient operation in the release direction of the clutch C1 is completed is established. The first clutch disengagement determination can determine success or failure from the rise of the turbine rotational speed NT, and FIG. 7 shows that the turbine rotational speed NT is blowing up slightly before time t2 until time t3. Yes. From time t2, the C1 hydraulic pressure P _C1 can maintain the clutch C1 in the released state or substantially released state in the neutral control, and also responds when returning from the neutral control by reducing the play of the clutch piston of the clutch C1. The hydraulic pressure P _C1N is maintained so that the clutch C1 can be engaged with good _performance .

Also, stop in the lock-up clutch engagement control means 88, first the time t2 the clutch release decision is affirmative, the lockup clutch command oil pressure P the _SLU, lock-up differential pressure P _LU aim zero and lock-up clutch 46 In order to prevent the engagement force from being generated, for example, it is raised in a step shape, and the state of the lockup clutch instruction hydraulic pressure P _SLU is maintained from the time t2 until the time t3 when the predetermined waiting time TIME _WT elapses. The waiting time TIME _WT is experimentally obtained in advance for the time required for the blow-up of the turbine rotational speed NT accompanying the releasing operation of the clutch C1 at the start of the neutral control to be set to the required time. Yes. At time t3, since the waiting time TIME _WT has elapsed from time t2, a lockup engagement start condition is established in which engagement of the lockup clutch 46 is started in the stopped lockup clutch engagement control. Then, when the vehicle is stopped, the lockup clutch engagement control means 88 increases the lockup clutch command hydraulic pressure P _SLU with a sweep of a predetermined gradient from the time point t3. That is, the engagement force of the lockup clutch 46 starts to be generated from time t3. FIG. 7 also shows that the lockup differential pressure _PLU also increases from the time t3 as the sweep of the lockup clutch command oil pressure P _SLU increases from the time t3. As described above, the stop lock-up clutch engagement control means 88 is, in the stop lock-up clutch engagement control, after the time t2 when the transient operation in the release direction of the clutch C1 in the neutral control is completed. At time t3, the lockup clutch 46 starts to generate an engagement force. Here, as indicated by a broken line A01 in FIG. 7, the turbine rotational speed NT is increased from the time point t3 so as to coincide with the engine rotational speed NE by the engagement force of the lockup clutch 46. Thus, the engine load may temporarily increase due to the inertia of the turbine impeller 14b and the input shaft 26. In view of this, it is preferable to temporarily increase the amount of fuel supplied to the engine 10 at time t3 in order to suppress fluctuations in the engine speed NE. In the time chart of the turbine rotational speed NT, the turbine rotational speed NT is increased from the time point t3 so as to coincide with the engine rotational speed NE by the engaging force of the lock-up clutch 46. If the combined control is not executed, the turbine rotational speed NT during the neutral control is maintained substantially the same as the rotational speed at time t3.

The time point t4 indicates the time point when the lockup clutch command hydraulic pressure P _SLU reaches the hydraulic pressure at which the lockup clutch 46 is completely engaged. That is, in FIG. 7, the turbine rotational speed NT that had been lower than the engine rotational speed NE until the time t4 coincides with the engine rotational speed NE at the time t4. Whether or not the lock-up clutch 46 has been completely engaged can be determined from the rotational speed difference between the engine rotational speed NE and the turbine rotational speed NT. At time t4, the lockup clutch 46 is in a fully engaged state, and therefore a lockup engagement end condition for ending the sweep-up of the lockup clutch command hydraulic pressure P _SLU for fully engaging the lockup clutch 46 is established. To do. Since the lock-up clutch 46 is completely engaged from the time point t4, the locked-up clutch engagement control means 88 during the stop maintains the lock-up clutch command hydraulic pressure P _SLU at the hydraulic pressure at the time point t4. The lockup differential pressure _PLU is maintained at the oil pressure at the time t4, and the fully engaged state of the lockup clutch 46 is maintained.

In the period from time t4 to time t5, since the turbine rotational speed NT is increased compared to the previous time t2, the first clutch differential rotation .DELTA.N _C1 increases in response to an increase in the turbine speed NT Figure 3 As shown, the drag torque TD _C1 of the clutch C1 decreases, and the engine load decreases compared to before t2. Therefore, the fuel supply amount for maintaining the idling state of the engine 10 is reduced from the time point t4 to the time point t5 as compared with the time before the time point t2. For example, the fuel supply amount may be reduced by switching a fuel supply amount reference map that experimentally determines the fuel supply amount at the time of idling of the engine 10, or the idle rotation speed of the engine 10 is maintained at a predetermined rotation speed. As described above, the fuel supply amount may be reduced by adjusting the fuel supply amount by feedback control.

At time t5, for example, the neutral control condition is switched from established to not established because the braking operation of the vehicle 6 is released, for example. In other words, a neutral control return condition (N control return condition) for returning from the neutral control is satisfied at time t5. Then, the neutral control execution means 82 starts to end the neutral control from time t5. Specifically, at time t5, the C1 oil pressure P _C1 is slightly increased in a stepped manner from the oil pressure P _C1N before time t5 so that the engagement operation of the clutch C1 can be started immediately. In the C1 oil pressure P _C1 after the pulling up, the clutch C1 is still released or substantially released. After the release of the lockup clutch 46 described later at time t5, that is, after the lockup clutch command hydraulic pressure P _SLU becomes zero and the release operation of the lockup clutch 46 is completed, the C1 hydraulic pressure P _C1 is swept at a predetermined gradient. The clutch C1 starts to increase and the engagement force of the clutch C1 begins to increase. At time t7, the clutch C1 reaches the fully engaged state. At time t7, the C1 hydraulic pressure P _C1 steadily engages the clutch C1 completely. The oil pressure to be maintained, that is, the oil pressure before starting the neutral control is increased stepwise. This time t7 is the end point of the neutral control.

At the time t5, the neutral control condition is switched from established to not established, so that the control execution flag switching means 84 switches the control execution flag FLG1act from ON to OFF. Therefore, the stopped lock-up clutch engagement control means 88 starts ending the stopped lock-up clutch engagement control from time t5. Specifically, the locked lock-up clutch engagement control means 88 starts to decrease the lock-up clutch command hydraulic pressure P _SLU at a predetermined gradient from time t5 in order to start the releasing operation of the lock-up clutch 46. As the lockup clutch command hydraulic pressure P _SLU decreases, the lockup differential pressure _PLU also decreases from time t5. At time t6, the lockup differential pressure _PLU becomes zero and the lockup clutch 46 is completely released. ing. At time t6, the lock-up clutch 46 is released, but the engaging force of the clutch C1 is zero or substantially zero. Therefore, the turbine rotational speed NT is once decreased, and from the time t6 until the engaging force of the clutch C1 starts increasing. It is constant. Then, the lockup clutch command hydraulic pressure P _SLU reaches zero slightly after time t6. When the lock-up clutch command hydraulic pressure P _SLU reaches zero, the lock-up clutch engagement control during stop is terminated. As shown after time t5 in FIG. 7, when the neutral control is finished, the lock-up clutch engagement control means 88 during stoppage reduces the lock-up clutch command hydraulic pressure P _SLU by a predetermined gradient to lock up. The clutch 46 is released. Then, the neutral control execution means 82 brings the clutch C1 into a fully engaged state after the lockup clutch 46 is released, that is, after time t6.

Figure 8 is a hydraulic oil temperature TEMP _OIL of the stop in the lock-up clutch engagement lockup cause engagement force to the lock-up clutch 46 in the control differential pressure P _LU and the automatic transmission 12 hydraulic oil temperature TEMP _OIL i.e. the clutch C1 of It is a figure showing an example of the relationship. As shown in the time chart of FIG. 7, a stop in the lock-up clutch engagement control means 88 maintains the lock-up clutch 46 at the time t4 ~ t5 fully engaged state, the lock-up differential pressure P _LU or locked at that time the engagement force of the lock-up clutch 46 corresponding to the up differential pressure P _LU is determined independent of the hydraulic oil temperature TEMP _oIL, stop in the lock-up clutch engagement control means 88, in the stationary-state lockup clutch engagement control As the hydraulic oil temperature TEMP _OIL is higher, the engagement force of the lockup clutch 46 may be reduced. Specifically, as shown in FIG. 8, the higher the hydraulic oil temperature TEMP _OIL, is that it does not harm in reducing the lock-up differential pressure P _LU in t4 ~ t5 point in FIG. For example, the relationship shown in FIG. 8 is that the engagement of the lockup clutch 46 does not deteriorate the response at the time of return from the neutral control when the hydraulic oil temperature TEMP _OIL is high, and the hydraulic oil temperature TEMP _OIL is low. Sometimes it is experimentally set in advance so that the drag torque TD _C1 of the clutch C1 can be sufficiently reduced. If the relationship shown in FIG. 8 is followed, in FIG. The lockup clutch command oil pressure P _SLU is controlled so that the pressure P _LU becomes a hydraulic pressure determined based on the hydraulic oil temperature TEMP _OIL from the relationship shown in FIG. Incidentally, since the lockup clutch command hydraulic pressure P _SLU is controlled according to the relationship shown in FIG. 8, for example, the lockup clutch 46 may slip at the time t4 to t5 in FIG.

Figure 9 is a diagram showing an example of the relationship between the lock-up differential pressure causes the engaging force in the lock-up clutch 46 in the lock-up clutch engagement control during a stop P _LU and the engine rotational speed NE. As shown in the time chart of FIG. 7, a stop in the lock-up clutch engagement control means 88 maintains the lock-up clutch 46 at the time t4 ~ t5 fully engaged state, the lock-up differential pressure P _LU or locked at that time the engagement force of the lock-up clutch 46 corresponding to the up differential pressure P _LU is determined independent of the hydraulic oil temperature TEMP _oIL, stop in the lock-up clutch engagement control means 88, in the stationary-state lockup clutch engagement control The higher the engine speed NE during the control, the smaller the engagement force of the lockup clutch 46 may be. Specifically, as shown in FIG. 9, as the engine rotational speed NE is higher, it is that it does not harm in reducing the lock-up differential pressure P _LU in t4 ~ t5 point in FIG. For example, the engine rotation speed NE during the neutral control, that is, the idle rotation speed of the engine 10 is controlled so as to increase as the engine water temperature TEMP _W decreases, so the engine rotation speed NE at the time t4 to t5 in FIG. It depends on the water temperature TEMP _W. For example, the relationship shown in FIG. 9 is such that the drag torque TD _C1 of the clutch C1 can be sufficiently reduced, and the responsiveness of the lockup clutch 46 and the clutch C1 at the time of return from the neutral control is reduced. not is preset experimentally as, if according to the relationship shown in FIG. 9, FIG. 7, based on the relationship shown in the lock-up differential pressure P _LU is 9 at time t4 ~ t5 the engine rotational speed NE The lockup clutch instruction hydraulic pressure P _SLU is controlled so that the hydraulic pressure is determined by the above. Incidentally, since the lockup clutch command hydraulic pressure P _SLU is controlled according to the relationship shown in FIG. 9, for example, the lockup clutch 46 may slip at the time t4 to t5 in FIG. In the lockup clutch engagement control during stopping, the lockup differential pressure _PLU may be controlled according to a relationship in which the relationship shown in FIG. 8 and the relationship shown in FIG. 9 are combined with each other.

FIG. 10 is a flowchart for explaining a first main part of the control operation of the electronic control unit 52, that is, a control operation for executing the neutral control and switching the control execution flag FLG1act. The control operation shown in FIG. 10 is executed alone or in parallel with other control operations.

First, in a step (hereinafter, “step” is omitted) SA1 corresponding to the neutral control condition determining means 80, it is determined whether or not the neutral control condition is satisfied. If the determination of SA1 is affirmative, that is, if the neutral control condition is satisfied, the process proceeds to SA2. On the other hand, if the determination of SA1 is negative, that is, if the neutral control condition is not satisfied, the process proceeds to SA6.

In the SA2 corresponding to the neutral control execution means 82, the neutral control is executed. If the neutral control is already being executed, the execution is continued. After SA2, the process proceeds to SA3.

In SA3, it is determined whether the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 is higher than a predetermined oil temperature lower limit value TEMP1 _OIL and the hydraulic oil temperature TEMP _OIL is lower than a predetermined oil temperature upper limit value TEMP2 _OIL. Is done. When the determination of SA3 is affirmative, that is, when the hydraulic oil temperature TEMP _OIL is higher than a predetermined oil temperature lower limit value TEMP1 _OIL and the hydraulic oil temperature TEMP _OIL is lower than a predetermined oil temperature upper limit value TEMP2 _OIL. Move on to SA4. On the other hand, if the determination at SA3 is negative, the operation goes to SA5.

In SA4, the control execution flag FLG1act is set to ON. Here, the stop lock-up clutch engagement control executed according to the control execution flag FLG1act has the drag torque TD _C1 of the clutch C1 during the neutral control (N control), and the clutch C1 has details. Since this control is executed for the purpose of reducing the drag torque TD _C1 of the friction material, it may be called friction control drag torque reduction control during N control. Further, the control execution flag FLG1act may be referred to as N-control friction material drag torque reduction control execution flag FLG1act.

In SA5, the control execution flag FLG1act is set to OFF. Also in SA6, the control execution flag FLG1act is set to OFF. After SA6, the process proceeds to SA7. SA3 to SA6 correspond to the control execution flag switching means 84.

In SA7 corresponding to the neutral control execution means 82, the neutral control is terminated. In other words, the end of the neutral control is a return from the neutral control. If the neutral control has not been executed because it has already ended, the state in which the neutral control has not been executed is continued.

FIG. 11 is a flowchart for explaining a second main part of the control operation of the electronic control unit 52, that is, a control operation for executing the vehicle stop lock-up clutch engagement control in parallel with the neutral control. The control operation shown in FIG. 11 is executed alone or in parallel with other control operations.

First, in SB1, it is determined whether or not the control execution flag FLG1act (the N-control friction material dragging torque reduction control execution flag FLG1act) that is set and changed in any of SA4 to SA6 in FIG. 10 is ON. . If the determination at SB1 is affirmative, that is, if the control execution flag FLG1act is ON, the process proceeds to SB2. On the other hand, when the determination of SB1 is negative, that is, when the control execution flag FLG1act is OFF, the determination of SB1 is made again. In short, SB1 continues until the control execution flag FLG1act is turned on.

In SB2, execution of the stop-time lockup clutch engagement control (friction material drag torque reduction control during N control) is started. After SB2, the process proceeds to SB3.

In SB3, execution of the locked lock-up clutch engagement control is continued. After SB3, the process proceeds to SB4.

In SB4, as in SB1, it is determined whether or not the control execution flag FLG1act is ON. When the determination of SB4 is affirmed, that is, when the control execution flag FLG1act is ON, the process proceeds to SB3. In short, SB3 continues as long as the control execution flag FLG1act is ON. On the other hand, when the determination of SB4 is negative, that is, when the control execution flag FLG1act is OFF, the process proceeds to SB5. SB1 and SB4 correspond to the control execution flag determination means 86.

In SB5, the above-described lock-up clutch engagement control is stopped. Note that SB2, SB3, and SB5 correspond to the stop lock-up clutch engagement control means 88.

According to the present embodiment, when the control execution flag FLG1act is ON, the lock-up clutch engagement control means 88 during stopping generates the engagement force in the lock-up clutch 46 during the execution of the neutral control. Lock-up clutch engagement control is executed while the vehicle is stopped. In this way, during the execution of the neutral control, the turbine rotational speed NT is increased by the engaging force of the lockup clutch 46 and the rotational speed on the input side (engine side) of the clutch C1 is also increased, thereby locking. The first clutch differential rotation ΔN _C1 becomes larger than when the up clutch 46 is released, and the drag torque TD _C1 of the clutch C1 decreases as shown in FIG. As a result, the engine load of the engine 10 in the idling state during the neutral control is reduced, and the fuel consumption of the vehicle 6 can be improved.

Further, according to the present embodiment, the control execution flag switching means 84 is configured such that the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 is higher than the oil temperature lower limit value TEMP1 _OIL and the hydraulic oil temperature TEMP _OIL is the oil temperature upper limit. The control execution flag that switches execution of the locked-up lock-up clutch engagement control when the neutral control condition determination means 80 determines that the neutral control condition is satisfied when the value is lower than the value TEMP2 _OIL. Set FLG1act to ON. The hydraulic oil temperature range from the oil temperature lower limit value TEMP1 _OIL to the oil temperature upper limit value TEMP2 _OIL is the change in the hydraulic oil temperature TEMP _OIL from the cold state of the automatic transmission 12 to the steady state when the warm-up is completed. It is provided near the low temperature side in the range. That is, the control execution flag switching means 84, as the hydraulic oil temperature TEMP _OIL of the automatic transmission 12 (hydraulic oil temperature TEMP _OIL of vehicle power transmission device 9) is low, the stationary-state lockup clutch engagement control of the execution opportunities Will be increased. Here, since the responsiveness of the clutch C1 is lower when the hydraulic oil temperature TEMP _OIL is low than when it is high, even when the lockup clutch 46 is engaged during the neutral control, The responsiveness hardly deteriorates due to the engagement of the lockup clutch 46. Since as drag torque TD _C1 of the clutch C1 is liable person at a low temperature of the working oil temperature TEMP _OIL becomes larger than at a high temperature is shown in FIG. 3, the stationary-state lockup at low temperatures of the working oil temperature TEMP _OIL The fuel efficiency improvement effect by clutch engagement control becomes large. The relationship between the fuel efficiency improvement effect and the hydraulic oil temperature TEMP _OIL can also be understood from the fact that the limit speed ratio e0 becomes smaller as the hydraulic oil temperature TEMP _OIL is lower in the range of the arrow AR01 in FIG. On the contrary, when the hydraulic oil temperature TEMP _OIL is high, if the lock-up clutch 46 is engaged during the neutral control, the influence on the responsiveness at the time of return from the neutral control is likely to increase, as can be seen from FIG. When the hydraulic oil temperature TEMP _OIL is high, the fuel efficiency improvement effect by the locked lockup clutch engagement control is low. Therefore, it is possible to effectively obtain the advantage that fuel efficiency is improved by the lock-up clutch engagement control during stopping.

Further, according to the present embodiment, the stop-up lockup clutch engagement control means 88 locks up as the hydraulic oil temperature TEMP _OIL of the vehicle power transmission device 9 is higher in the stop-up lockup clutch engagement control. Even if the engagement force of the clutch 46 is reduced, there is no problem. In other words, when the engagement force is generated in the lock-up clutch 46 during the neutral control, the engagement force of the lock-up clutch 46 is reduced as the hydraulic oil temperature TEMP _OIL of the vehicle power transmission device 9 is higher. It does not matter. By doing so, it is possible to suppress the influence of the engagement of the lockup clutch 46 on the responsiveness at the time of return from the neutral control when the hydraulic oil temperature TEMP _OIL has good responsiveness of the clutch C1. it can. On the other hand, since the response of the clutch C1 is originally not good when the hydraulic oil temperature TEMP _OIL is low, the engagement of the lock-up clutch 46 hardly affects the response at the time of return from the neutral control, and the locked while stopped. It is possible to sufficiently obtain the fuel efficiency improvement effect by the up clutch engagement control.

Further, according to this embodiment, as shown in the time chart of FIG. 7, the stop lock-up clutch engagement control means 88 is configured to release the clutch C <b> 1 in the neutral control in the stop lock-up clutch engagement control. After the time t2 when the transitional movement in the direction ends, the lockup clutch 46 starts to generate an engaging force from the time t3. In other words, when an engagement force is generated in the lock-up clutch 46 during the execution of the neutral control, after the transient operation in the release direction of the clutch C1 in the neutral control is completed, the lock-up clutch 46 is engaged. Start to produce a resultant force. Therefore, compared with the case where the engagement force is generated in the lockup clutch 46 before the release operation of the clutch C1, the fluctuation range of the temporary engine load when the engagement force is generated in the lockup clutch 46 can be suppressed. It is possible to suppress the deterioration of fuel consumption due to the temporary fluctuation of the engine load.

In addition, according to the present embodiment, the lock-up clutch engagement control means 88 during stopping is the engagement of the lock-up clutch 46 as the engine speed NE during the control increases in the lock-up clutch engagement control during stop. The resultant force can be reduced. In other words, when the engagement force is generated in the lock-up clutch 46 during the neutral control, the engagement force of the lock-up clutch 46 may be reduced as the engine speed NE is higher. . Here, during the neutral control, the first clutch differential rotation ΔN _C1 increases as the engine speed NE increases, and the drag torque TD _C1 of the clutch C1 tends to decrease. Therefore, if this is done, the effect of improving the fuel efficiency by the lock-up clutch engagement control during stopping can be prevented by reducing the engagement force of the lock-up clutch 46 in consideration of the engine speed NE. In addition, it is possible to improve the responsiveness of releasing the lockup clutch 46 when the lockup clutch engagement control during the stop is finished.

Further, according to the present embodiment, the clutch C1 is a power interrupting device that is brought into a slipping state or a releasing state during execution of the neutral control and is engaged when returning from the neutral control. It is a friction clutch. Accordingly, since a wet friction clutch is often used as the power interrupting device, the present invention can be widely applied to specific vehicles.

As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

For example, in FIG. 7 of the above-described embodiment, the C1 oil pressure P _C1 is maintained at the oil pressure P _C1N from the time t2 to the time t5, but may be zero.

In FIG. 7 of the above-described embodiment, the turbine rotational speed NT matches the engine rotational speed NE from the time t4 to the time t5, and the lockup clutch 46 is in a fully engaged state. The lockup clutch 46 only needs to generate an engagement force between the time t4 and the time t5. For example, the lockup clutch 46 may be slipped without being completely engaged.

In the above-described embodiment, the torque converter 14 is used as a fluid transmission device. For example, the torque converter 14 may be replaced with a fluid coupling having no torque amplification action.

In the above-described embodiment, the automatic transmission 12 is a stepped automatic transmission, but may be a CVT capable of continuously shifting. When the automatic transmission 12 is a CVT, a friction clutch capable of interrupting power transmission is interposed between the turbine shaft of the torque converter 14 and the input shaft 26 of the automatic transmission 12. The friction clutch corresponds to the power interrupting device of the present invention.

In the above-described embodiment, the automatic transmission 12 is interposed between the torque converter 14 and the drive wheel 38. The automatic transmission 12 is connected to the turbine impeller 14b of the torque converter 14 and the drive wheel. 38 may be replaced with a power interrupting device such as a clutch C1 that selectively cuts off power transmission to and from the power source 38.

Further, in the above-described embodiment, in the time chart of FIG. 7, due to the engagement of the lock-up clutch 46, the turbine rotation speed NT is increased from the time t3 to the time t4 until it matches the engine rotation speed NE. In the lock-up clutch engagement control during stopping, it is sufficient that an engagement force is generated in the lock-up clutch 46. For example, the turbine rotation speed NT is increased from the rotation speed at time t3, and the turbine rotation speed NT at time t4 to t5 is increased. It does not matter if it is below the engine speed NE.

In the above-described embodiment, the flowchart of FIG. 10 includes SA3 and SA5. However, the flowchart of FIG. 10 does not include SA3 and SA5, and may be shifted to SA4 after SA2. There is no problem.

Further, in the present embodiment described above, the control execution flag switching means 84, the lower the hydraulic oil temperature TEMP _OIL of the working oil temperature TEMP _OIL i.e. the clutch C1 of the automatic transmission 12, the stop in the lock-up clutch engagement control while increasing the execution opportunities, execution opportunities of the stop in the lock-up clutch engagement control, may be much lower the hydraulic oil temperature TEMP _oIL throughout the range of variation of hydraulic oil temperature TEMP _oIL, hydraulic oil temperature in a portion of the range of variation of TEMP _oIL may be much lower the hydraulic oil temperature TEMP _oIL.

Further, in the present embodiment described above, the relationship between the hydraulic oil temperature TEMP _OIL lockup differential pressure P _LU and clutch C1 illustrated in FIG. 8, the higher its hydraulic fluid temperature TEMP _OIL, lock-up differential pressure P _LU that is, the engagement force of the lock-up clutch 46 corresponding to the lock-up differential pressure P _LU is reduced, the engagement force of the lock-up clutch 46, a high hydraulic oil temperature TEMP _oIL throughout the range of variation of hydraulic oil temperature TEMP _oIL more may be made of small, hydraulic oil temperature TEMP _oIL in a portion of the variation range of the working oil temperature TEMP _oIL may be made of higher smaller.

Further, in the above-described embodiment, in the relationship between the lockup differential pressure _PLU and the engine speed NE illustrated in FIG. 9, the higher the engine speed NE, the higher the lockup differential pressure _PLU, that is, the lockup differential pressure. the engagement force of the lock-up clutch 46 corresponding to the P _LU but decreases the engaging force of the lock-up clutch 46, be comprised small throughout the range of variation of the engine rotational speed NE as the engine rotational speed NE is higher Alternatively, the engine rotational speed NE may be smaller as the engine rotational speed NE is higher in a part of the change range of the engine rotational speed NE.

6: Vehicle 9: Vehicle power transmission device 10: Engine 14: Torque converter (fluid transmission device)
14a: Pump impeller (input member)
14b: Turbine wheel (output member)
38: Drive wheel 46: Lock-up clutch 52: Electronic control device (control device)
C1: Clutch (power interrupter)

Claims (6)

1. A lockup clutch that mechanically directly connects the input and output members of the fluid transmission device that transmits engine power to the drive wheels, and the power transmission between the output member of the fluid transmission device and the drive wheels is interrupted. A vehicle power transmission device comprising a power interrupting device, wherein the vehicle power transmission device executes neutral control for setting the power interrupting device to a slipping state or a releasing state while the vehicle is stopped.
   An engaging force is generated in the lock-up clutch during execution of the neutral control. A control device for a vehicle power transmission device, characterized in that:
2. 2. The vehicle according to claim 1, wherein the lower the hydraulic oil temperature of the vehicle power transmission device is, the greater the number of execution opportunities for the control that causes the lockup clutch to generate an engaging force during the execution of the neutral control. Power transmission device control device.
3. When the engagement force is generated in the lockup clutch during the neutral control, the engagement force of the lockup clutch is decreased as the hydraulic oil temperature of the vehicle power transmission device is higher. The control device for a vehicle power transmission device according to claim 1 or 2.
4. When an engagement force is generated in the lock-up clutch during the neutral control, the engagement force is applied to the lock-up clutch after the transient operation in the release direction of the power interrupting device in the neutral control is completed. The control device for a vehicle power transmission device according to any one of claims 1 to 3, wherein the control device for the vehicle power transmission device is started.
5. The engagement force of the lockup clutch is made smaller as the rotational speed of the engine is higher when the engagement force is generated in the lockup clutch during the execution of the neutral control. The control device for a vehicle power transmission device according to any one of the above.
6. The control device for a vehicle power transmission device according to any one of claims 1 to 5, wherein the power interrupting device is a wet friction clutch.
   
   

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