Automatic transmission control device

Abstract

To improve the transmission responsiveness of a drive force, and to avoid an unintentional stop of an engine, in a situation that the viscosity of a working fluid for operating an automatic gear change becomes high, and the followability of actual pressure with respect to an indication value of hydraulic pressure is deteriorated.SOLUTION: A control device of an automatic transmission is arranged in a drive force transmission path for transmitting the power of an engine to wheels, and forms a prescribed gear change stage by changing an engagement state of a friction engagement element. The control device comprises: a traveling range standby control part for making a part of a traveling range forming element which forms a traveling range engaged before being switched to the traveling range out of the friction engagement element; and a working fluid state determination part for determining whether or not the viscosity of a working fluid for operating the friction engagement element is in a response delay state that a response delay with respect to an indication value of hydraulic pressure occurs. When the response delay state is determined, the traveling range standby control part raises an indication value of hydraulic pressure for making a brake element engaged from hydraulic pressure at which a release state of the brake element is maintained after an oil temperature of the working fluid reaches a threshold or higher.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a control device for an automatic transmission. [Background technology]

[0002] Conventionally, automatic transmissions are known that are arranged in a drive force transmission path for transmitting the output of an engine as a power source to the wheels of a vehicle. The automatic transmission is arranged downstream of the engine in the drive force transmission direction in the drive force transmission path. The automatic transmission switches between a non-driving range, such as a parking range (P) or a neutral range (N), and a driving range that allows forward and reverse travel, or achieves any gear position, by changing the combination of engagement states of multiple friction engagement elements.

[0003] Friction engagement elements in an automatic transmission are operated by hydraulic oil (ATF: Automatic Transmission Fluid) and are brought into a desired engagement state by controlling the hydraulic pressure. In an automatic transmission, some of the friction engagement element devices that are engaged to realize a driving range may be engaged prior to the timing of an operation to shift to the driving range (see, for example, Patent Document 1). An automatic transmission includes brake elements as friction engagement elements, and these brake elements and clutch elements may correspond to some of the friction engagement elements that are engaged to realize the driving range. These brake elements and clutch elements may be engaged prior to the timing of switching to the driving range. This allows the automatic transmission to quickly and responsively switch to the driving range when the driver performs an operation to select the driving range, thereby improving the responsiveness of the transmission of driving force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-17822 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the environment in which a vehicle is placed, the viscosity of the hydraulic fluid used to control the automatic transmission may increase, causing a deterioration in the ability of the actual pressure to follow the hydraulic pressure command value. When engaging brake elements or clutch elements, these elements can be smoothly engaged by gradually increasing the hydraulic pressure command value. However, in a situation where the ability of the actual pressure to follow the hydraulic pressure command value has deteriorated, it is possible that the brake elements, etc., may suddenly enter an engaged state at an unintended timing.

[0006] Some of the elements included in the automatic transmission are linked to the engine output shaft, and depending on their characteristics, they may affect the elements linked to the engine output shaft even when the vehicle is not in a driving range. For this reason, if a friction engagement element such as a brake element suddenly enters an engaged state at an unintended timing, this may affect the elements linked to the engine output shaft, causing the engine to stall.

[0007] Patent Document 1 does not consider any measures to deal with such a phenomenon.

[0008] Therefore, the present invention aims to improve the responsiveness of the transmission of driving force and to avoid unintentional engine stalls in situations where the viscosity of the hydraulic oil that operates the automatic shifting increases and the ability of the actual pressure to follow the indicated hydraulic pressure value deteriorates. [Means for solving the problem]

[0009] The above object is achieved by an automatic transmission control device that is arranged in a driving force transmission path that transmits the power of an engine, which is a driving source, to wheels, and that forms a desired gear by changing the engagement state of a plurality of friction engagement elements, the automatic transmission control device comprising: a driving range standby control unit that performs driving range standby control to engage some of the driving range forming elements that form a driving range, among the plurality of friction engagement elements, before switching to the driving range; and a hydraulic oil state determination unit that determines, when the driving range standby control is started, whether the viscosity of the hydraulic oil that operates the friction engagement elements is in a delayed response state that causes a delayed response to a hydraulic pressure command value, and when it is determined that the viscosity of the hydraulic oil is in a delayed response state, the driving range standby control unit increases the hydraulic pressure command value that engages a brake element included in the driving range forming element from the hydraulic pressure at which the brake element is maintained in a released state after the oil temperature of the hydraulic oil becomes equal to or higher than a predetermined threshold value.

[0010] In the above-described control device for the automatic transmission, the travel range standby control unit can be configured to, when it is determined that the viscosity of the hydraulic oil is in a delayed response state, increase the hydraulic pressure command value for engaging the brake element included in the travel range forming element after the oil temperature of the hydraulic oil becomes equal to or higher than a predetermined threshold and a predetermined standby period has elapsed during which the hydraulic oil pressure command value is kept at the state before engagement begins.

[0011] Furthermore, in the above-described automatic transmission control device, the standby period set when it is determined that a delayed response state exists can be longer than the standby period set when the viscosity of the hydraulic oil at the time of starting the travel range standby control is in a response tracking state in which the viscosity of the hydraulic oil follows the hydraulic pressure command value. [Effects of the Invention]

[0012] The invention disclosed in this specification improves the responsiveness of the transmission of driving force and prevents the engine from stopping unintentionally in situations where the viscosity of the hydraulic oil that operates the automatic shifting is high and the ability of the actual pressure to follow the indicated hydraulic pressure value is reduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a hybrid vehicle equipped with an automatic transmission control device according to an embodiment. [Figure 2] FIG. 2(A) is a schematic diagram showing an example of an automatic transmission, FIG. 2(B) is a schematic diagram showing elements that cause rotation speed fluctuations when brake B2 is engaged in an automatic transmission, and FIG. 2(C) is a schematic diagram showing elements that cause inertia changes when brake B2 is engaged in an automatic transmission. [Figure 3] FIG. 3 is a diagram showing the relationship between the gear positions achieved by the automatic transmission shown in FIG. 2 and the engaged and released states of the friction engagement elements. [Figure 4] FIG. 4 is a flowchart showing an example of control executed by the control device for the automatic transmission according to the embodiment. [Figure 5] FIG. 5 is an example of a time chart showing changes in various values ​​accompanying the control executed by the control device for the automatic transmission according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions and proportions of the various parts in the drawings may not be exactly the same as those in reality. In addition, some details may be omitted in the drawings.

[0015] (Embodiment) [Vehicle configuration] 1 is a schematic diagram of a hybrid vehicle (hereinafter simply referred to as "vehicle") 1 to which the present invention is applied. The vehicle 1 includes a driving force transmission path 10 from an engine 12 to wheels 24, and an ECU (Electronic Control Unit) 100 that performs various controls for the vehicle 1. As will be described in detail later, the ECU 100 functions as a control device for an automatic transmission 17.

[0016] The driving force transmission path 10 includes, in order from the side closest to the engine 12, a K0 clutch 13, a motor generator (MG) 14, a torque converter 15, an oil pump 16, and an automatic transmission (A / T) 17, inside a transmission case 11 which is a non-rotating member fixed to the body of the vehicle 1. The driving force transmission path also includes a propeller shaft 19 connected to an output shaft 18 of the automatic transmission 17, a differential gear device 20 connected to the propeller shaft 19, and an axle 21 connected to the differential gear device 20. The axle 21 is provided on both sides of the differential gear device 20, and each axle has a wheel 24 mounted thereon.

[0017] When the K0 clutch 13 is engaged, the power of the engine 12 is transmitted from an engine output shaft 22 that connects the engine 12 and the K0 clutch 13 to the K0 clutch 13, the torque converter 15, the transmission input shaft 23, and the automatic transmission 17. The power of the engine 12 is then transmitted from the automatic transmission 17 to wheels 24 via a propeller shaft 19, a differential gear device 20, and an axle 21 in this order.

[0018] The torque converter 15 is a fluid-type power transmission device that transmits driving force input to the pump wheel 15a to the automatic transmission 17 via fluid. The pump wheel 15a is an input-side rotating element that inputs driving force from the engine 12 to the torque converter 15, and is connected to the engine 12 via the K0 clutch 13 and an engine output shaft 22. The turbine wheel 15b of the torque converter 15 is an output-side rotating element of the torque converter 15, and is connected to a transmission input shaft 23, which is an input rotating member of the automatic transmission 17, by spline fitting or the like so as to be non-rotatable relative to the transmission input shaft 23. The torque converter 15 is equipped with a lock-up clutch 26. The lock-up clutch 26 is a direct-coupled clutch provided between the pump wheel 15a and the turbine wheel 15b, and is hydraulically controlled to be placed in an engaged state, a slip state, or a disengaged state.

[0019] The motor generator 14 is an example of an electric motor and functions as a motor that generates mechanical driving force from electrical energy and as a generator that generates electrical energy from mechanical energy. The motor generator 14 can be used as a driving force source for generating driving force for traveling, either in place of the engine 12 or together with the engine 12. The motor generator 14 can generate electrical energy by regeneration from the driving force generated by the engine 12 or the driven force (mechanical energy) input from the wheels 24, and store the generated electrical energy in the power storage device 61 via the inverter 60. The motor generator 14 is connected to the pump wheel 15a, and power is transmitted between the electric motor MG and the pump wheel 15a. As a result, the motor generator 14, like the engine 12, is connected to the transmission input shaft 23 so as to be capable of transmitting power.

[0020] The oil pump 16 is a mechanical pump connected to the pump impeller 15a, and generates hydraulic oil pressure for controlling the torque capacity of the lock-up clutch 26, for controlling the engagement and disengagement of the K0 clutch 13, and for supplying lubricating oil to each part of the driving force transmission path 10. In addition to the mechanical oil pump 16, the vehicle 1 is also equipped with an electric oil pump 51. The electric oil pump 51 can obtain hydraulic oil pressure in situations where it is difficult to obtain hydraulic oil pressure from the oil pump 16.

[0021] The K0 clutch 13 is a wet-type multi-plate hydraulic friction engagement element in which multiple overlapping friction plates are pressed by a hydraulic actuator. The engagement and disengagement of the K0 clutch 13 are controlled by a hydraulic control circuit 50, which uses hydraulic pressure generated by the oil pump 16 as a source pressure. The K0 clutch 13 includes a pair of clutch rotating members, i.e., a clutch hub and a clutch drum, that are rotatable relative to each other in a disengaged state. One of the clutch rotating members (the clutch hub) is non-rotatably connected to the engine output shaft 22. The other clutch rotating member (the clutch drum) is non-rotatably connected to the pump wheel 15a of the torque converter 15. Thus, in an engaged state, the K0 clutch 13 rotates the pump wheel 15a integrally with the engine 12 via the engine output shaft 22. In a disengaged state, the K0 clutch 13 interrupts power transmission between the pump wheel 15a and the engine 12. The K0 clutch 13 also connects and disconnects the driving force transmission path 10 between the engine 12 and the motor-generator 14.

[0022] The automatic transmission 17 is disposed on the driving force transmission path 10 closer to the wheels 24 than the motor generator 14. A K0 clutch 13 is disposed between the engine 12 and the motor generator 14. When the K0 clutch 13 is engaged, the automatic transmission 17 is connected to the engine 12 and the driving force of the engine 12 is transmitted to the automatic transmission 17.

[0023] The automatic transmission 17 can achieve a desired gear by changing the engagement state of multiple friction engagement elements. The friction engagement elements in the automatic transmission 17 are, for example, hydraulically operated clutches and brakes, and gear changes are performed by switching between engagement and disengagement of any of these elements (i.e., by engaging and disengaging the friction engagement elements), thereby selectively establishing multiple gears (gears). The automatic transmission 17 of this embodiment is a planetary gear type multi-speed transmission. The automatic transmission 17 is a stepped transmission that performs so-called clutch-to-clutch gear shifting, which is commonly used in known vehicles, and changes the rotation of a transmission input shaft 23 and outputs it from an output shaft 18. The transmission input shaft 23 is a turbine shaft that is rotated by a turbine impeller 15b of the torque converter 15. In the automatic transmission 17, a predetermined gear is established in response to the driver's accelerator operation, vehicle speed V, etc., by controlling the engagement of the clutches and brakes.

[0024] [Driving range forming factors] FIG. 2(A) shows the configuration of an automatic transmission 17. The automatic transmission 17 changes the rotation of a transmission input shaft 23, which is connected to the turbine shaft of the torque converter 15 (see FIG. 1), in multiple stages and outputs the rotation from an output shaft 18. The automatic transmission 17 includes a single-pinion first planetary gear set 52, a double-pinion second planetary gear set 54, a single-pinion third planetary gear set 56, and a single-pinion fourth planetary gear set 58. The first planetary gear set 52 and the second planetary gear set 54 form a so-called Ravigneaux-type planetary gear train. The automatic transmission 17 also includes four clutches C1 to C4 and two brakes B1 and B2.

[0025] 3 shows the combinations of gears realized in the automatic transmission 17 and the engagement states of the friction engagement elements. The automatic transmission 17 establishes 10 forward gears (first gear "1st" to tenth gear "10th") with different gear ratios γ (= transmission input rotation speed NIN / output shaft rotation speed NOUT) depending on the combination of engagement states of the friction engagement elements. The transmission input rotation speed NIN is the rotation speed of the transmission input shaft 23, and the output shaft rotation speed NOUT is the rotation speed of the output shaft 18, and the output shaft rotation speed NOUT corresponds to the vehicle speed V. The automatic transmission 17 can also select a reverse gear "R."

[0026] When the vehicle 1 starts traveling, the first gear is normally selected. According to FIG. 3, the first gear is achieved by engaging the clutch C1, the clutch C2, and the brake B2. The reverse gear R for moving the vehicle 1 in reverse is achieved by engaging the clutch C1, the clutch C3, and the brake B2. Therefore, in this specification, the clutches C1, C2, and B2 are elements that define the forward travel range. The clutches C1, C3, and B2 are elements that define the reverse travel range. The torque capacity, i.e., the engagement force, of these clutches and brakes is changed by adjusting the pressure of a linear solenoid valve or the like in the hydraulic control circuit 50, and the engagement of these clutches and brakes is controlled.

[0027] Here, the characteristics of brake B2 will be described with reference to Figures 2(B) and 2(C). In Figure 2(B), the elements indicated by thick lines are elements that cause rotational speed fluctuations as the engagement state of brake B2 changes, and in Figure 2(C), the elements indicated by thick lines are elements that cause inertia changes as the engagement state of brake B2 changes. In Figure 2(C), the elements indicated by thick lines include transmission input shaft 23. Therefore, when transmission input shaft 23 is connected to engine output shaft 22, it is expected that the inertia change will affect engine 12. Therefore, depending on how brake B2 is engaged, the inertia change may affect engine 12, which may result in engine 12 stopping, or a so-called stall.

[0028] [Automatic transmission control device] Returning to FIG. 1 , the ECU 100 provided in the vehicle 1 will be described. The ECU 100 includes a so-called microcomputer equipped with a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 1 by utilizing the temporary storage function of the RAM and performing signal processing in accordance with programs previously stored in the ROM. The ECU 100 executes, for example, output control of the engine 12, drive control and regeneration control of the motor generator 14, shift control of the automatic transmission 17, torque capacity control of the lock-up clutch 26, and torque capacity control of the K0 clutch 13. The ECU 100 is configured as divided into sections for engine control, electric motor control, hydraulic control (shift control), etc., as needed, and in this embodiment, it functions as a control device for the automatic transmission 17. The following description will focus on the function as a control device for the automatic transmission 17.

[0029] As shown in the functional block diagram of FIG. 1, the ECU 100 includes a shift position determining unit 101, a driving range standby control unit 102, and a hydraulic oil state determining unit 103.

[0030] The shift position determination unit 101 determines the shift position of the shift lever 64, such as the "P", "N", "D", "R", or "S" position, detected by the shift position sensor 63 provided in the vehicle 1.

[0031] The driving range standby control unit 102 performs driving range standby control to engage some of the driving range forming elements described above before switching to the driving range. Specifically, the driving range standby control is a control to engage the clutch C2 and the brake B2, which are engaged to enable the automatic transmission 17 to realize the driving range of 1st or R, when the shift position is in the non-driving range of "P" or "N." By engaging the clutch C2 and the brake B2 in the non-driving range, for example, if the clutch C1 is engaged when the shift position is subsequently shifted to "D," all of the driving range forming elements for forward travel are engaged, allowing the vehicle 1 to immediately move forward. Also, by engaging the clutch C2 and the brake B2 in the non-driving range, for example, if the clutch C3 is engaged when the shift position is subsequently shifted to "R," all of the driving range forming elements for reverse travel are engaged, allowing the vehicle 1 to immediately move backward.

[0032] The hydraulic oil state determination unit 103 determines whether the viscosity of the hydraulic oil that operates the automatic transmission 17 is in a delayed response state, causing a delayed response to the command value of hydraulic pressure, or in a response tracking state, tracking the command value of hydraulic pressure, based on the value of the outside air temperature measured by the outside air temperature sensor 53 and the value of the oil temperature measured by the oil temperature sensor 50a. When the temperature of the environment in which the vehicle 1 is placed drops and the viscosity of the hydraulic oil increases, the fluidity of the hydraulic oil decreases, causing a delayed response to the command value of hydraulic pressure.

[0033] If the travel range standby control unit 102 executes the travel range standby control and outputs a hydraulic pressure command value for engaging the brake B2 when the viscosity of the hydraulic oil is in a response delay state, it is expected that the increase in the actual hydraulic pressure will be delayed relative to the hydraulic pressure command value. Therefore, the travel range standby control unit 102 changes the content of the travel range standby control in consideration of the determination result of the hydraulic oil state determination unit 103. The travel range standby control will be described below with reference to FIGS. 4 and 5.

[0034] [Driving range standby control] Referring to the time chart shown in FIG. 5, a starter drive command to start the engine 12 is issued at time t1. During the time period shown in the time chart shown in FIG. 5, the shift position is in the non-driving range of "P" or "N." The ECU 100 starts the driving range standby control at the timing when the starter drive command is issued. The engine 12 starts rotating by cranking at time t1, and increases its rotation speed toward complete combustion from time t2 to time t3. After time t4, the idling rotation speed is maintained. The ECU 100 also issues an engagement command to the K0 clutch 13 at time t3. The rotation speed of the motor-generator 14 begins to increase from time t3 and coincides with the engine rotation speed at time t4.

[0035] In step S1, the ECU 100 determines whether the engine 12 is being started at extremely low temperatures. Here, an extremely low temperature start means that the vehicle 1 is being started in an environment in which the hydraulic oil of the automatic transmission 17 is in a delayed response state. In this embodiment, an extremely low temperature start is determined when the outside air temperature measured by the outside air temperature sensor 53 is equal to or lower than a preset outside air temperature threshold. The outside air temperature threshold is set based on an outside air temperature that is determined in advance through simulations or calibration using an actual vehicle, at which a delayed response state occurs in the hydraulic oil. In step S1, instead of determining whether the engine 12 is being started at extremely low temperatures based on the outside air temperature, it is also possible to determine whether the engine 12 is being started at extremely low temperatures based on the oil temperature of the hydraulic oil.

[0036] If the ECU 100 makes a positive determination (Yes determination) in step S1, the ECU 100 proceeds to step S2. In step S2, the ECU 100 selects the extremely low temperature standby control. On the other hand, if the ECU 100 makes a negative determination (No determination) in step S1, the ECU 100 proceeds to step S3. In step S3, the ECU 100 selects the normal standby control.

[0037] Referring again to FIG. 5, the ECU 100 issues a command to drive the electric oil pump (EOP) 51 at time t3 when the starter drive command ends. The command to drive the electric oil pump 51 is issued after the starter drive command ends in order to avoid driving the starter and the electric oil pump 51 at the same time, as both consume power. The command to drive the electric oil pump 51 is issued from time t3 to time t5. This is because the command to apply hydraulic pressure to the brake B2 is issued at time t4. Although the engine 12 starts operating at time t4, there is a time lag before the mechanical oil pump 16 (see FIG. 1) starts operating and begins discharging oil. Therefore, the electric oil pump 51 is operated from time t3 to time t4.

[0038] In the cryogenic standby control selected in step S2, the ECU 100 waits for a predetermined standby period to elapse before increasing the hydraulic pressure command value for engaging the brake B2. In this embodiment, the standby period is set to the period from time t4 to time t8. This standby period is set in advance through simulation or calibration using an actual vehicle, allowing for the hydraulic fluid response delay to be eliminated. Referring to FIG. 5, the hydraulic pressure command value from time t4 to time t5, which is the beginning of the standby period, is set higher than the hydraulic pressure command value thereafter. This is because the hydraulic fluid is not flowing during the period up to time t4, and a higher command value is provided to initiate the flow of the non-flowing hydraulic fluid. This command value is similarly executed in the normal standby control described later. The hydraulic pressure command value from time t4 to time t8 is set to a value before the brake B2 is engaged, i.e., a value at which the brake B2 is gradually engaged by further increasing the hydraulic pressure from this state. This state is sometimes referred to as a packed state.

[0039] In step S4, which is performed following step S2, the ECU 100 determines whether the standby period has elapsed, that is, whether time t8 has elapsed. If the ECU 100 makes a positive determination in step S4, the ECU 100 proceeds to step S5. On the other hand, if the ECU 100 makes a negative determination in step S4, the ECU 100 repeats the processing of step S4 until the ECU 100 makes a positive determination in step S4.

[0040] In step S5, the ECU 100 determines whether the temperature of the hydraulic oil (ATF oil temperature) is equal to or higher than a predetermined threshold value based on the detection value of the oil temperature sensor 50a. This threshold value is preset as an oil temperature at which no response delay of the hydraulic oil occurs. Referring to FIG. 5, at time t7, the temperature of the hydraulic oil becomes higher than the threshold value. When the temperature of the hydraulic oil becomes higher than the threshold value in this way, the ECU 100 makes a positive determination in step S5. If the ECU 100 makes a positive determination in step S5, the ECU 100 proceeds to step S6. On the other hand, if the ECU 100 makes a negative determination in step S5, the ECU 100 repeats the processing of step S5 until a positive determination is made in step S5. The temperature of the hydraulic oil in step S5 may be estimated using a value correlated with the temperature of the hydraulic oil. The oil temperature of the hydraulic oil can be estimated by a conventionally known method, such as using a value estimated based on, for example, the outside air temperature, the oil temperature of the hydraulic oil when the engine 12 is running, the amount of heat accumulated in the flow path through which the hydraulic oil circulates, changes in the temperature of the cooling water circulating through the engine 12, etc.

[0041] 5 shows an example in which the hydraulic oil temperature exceeds the threshold value at time t7, which is earlier than time t8, but the oil temperature may also exceed the threshold value at a time later than time t8. In addition, in this embodiment, two determination items are set: whether the hydraulic oil temperature exceeds the threshold value and whether the standby period has elapsed. However, it is also possible to set only one of these determination items. Furthermore, the order of steps S4 and S5 does not matter, and steps S4 and S5 may be reversed or executed simultaneously.

[0042] In step S6, ECU 100 gradually increases the hydraulic pressure command value for engaging brake B2 to engage brake B2. Specifically, the hydraulic pressure command value is gradually increased from time t8. At time t8, the state in which the hydraulic oil response delay occurs is resolved and the ability of the actual pressure to follow the command value is ensured, so that brake B2 is prevented from suddenly engaging at an unintended timing and causing engine 12 to stall.

[0043] Meanwhile, even in the normal standby control selected in step S3, ECU 100 waits for an increase in the hydraulic pressure command value for engaging brake B2 until a predetermined standby period has elapsed. When normal standby control is performed, the viscosity of the hydraulic oil is in a response tracking state that follows the hydraulic pressure command value. Therefore, the standby period in normal standby control is set to the period from time t4 to time t6, which is shorter than the standby period in extremely low temperature standby control. In other words, the standby period in extremely low temperature standby control is set to a longer period than in normal standby control. The period from time t4 to time t6 is set as a period during which packing is completed and engagement of brake B2 can be started.

[0044] In step S7, which is performed following step S3, the ECU 100 determines whether the standby period has elapsed, that is, whether time t7 has elapsed. If the ECU 100 makes a positive determination in step S7, the ECU 100 proceeds to step S6. On the other hand, if the ECU 100 makes a negative determination in step S7, the ECU 100 repeats the processing of step S7 until the ECU 100 makes a positive determination in step S7. The processing of step S6 is the same as that after step S5, and therefore will not be described here.

[0045] In step S6, the brake B2 starts to be engaged, and the brake B2 is then engaged. Although not described here, the clutch C2 is also engaged. Due to its structure, the clutch C2 does not cause an inertia change, and even if it suddenly enters an engaged state, it will not stop the engine 12. Therefore, the clutch C2 can be engaged without any special control, unlike when the brake B2 is engaged.

[0046] In this embodiment, the automatic transmission 17 engages the clutch C2 and brake B2, which are part of the driving range forming elements, in the non-driving range before switching to the driving range. When the shift position is subsequently changed to, for example, the "D" range, the automatic transmission 17 immediately engages the clutch C1 to achieve the first gear and immediately put the vehicle 1 into a driving state. Also, when the shift position is changed to the "R" range, the automatic transmission 17 engages the clutch C3 to the auxiliary position to achieve the reverse gear R and immediately put the vehicle 1 into a reverse state.

[0047] [effect] In this embodiment, among the multiple friction engagement elements included in the automatic transmission 17, the clutch C2 and the brake B2, which are part of the drive range forming elements that form the drive range, are engaged before switching to the drive range. This results in high responsiveness in the transmission of driving force. Also, when the hydraulic oil that operates the brake B2 is in a response delay state, the hydraulic pressure command value for engaging the brake B2 is increased after the temperature of the hydraulic oil reaches or exceeds a threshold value. This prevents the brake B2 from suddenly entering an engaged state and causing the engine 12 to stop.

[0048] The above-described embodiments are merely examples for implementing the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention. Furthermore, it is obvious from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0049] 1 Hybrid vehicle (vehicle) 10 Drive force transmission path 11 Transmission case 12 Engine 13 K0 clutch 14 Motor generator 15 Torque converter 17 Automatic transmission (A / T) 18 Output shaft 19 Propeller shaft 20 differential gear device 21 axle 22 engine output shaft 23 transmission input shaft 24 Wheel 50 Hydraulic control circuit 50a Oil temperature sensor 51 Electric oil pump (EOP) 53 Outside air temperature sensor 63 Shift position sensor 100 control unit (ECU) 101 shift position determination unit 102 Travel range standby control unit 103 Hydraulic oil state determination unit

Claims

1. A control device for an automatic transmission, which is disposed in a driving force transmission path that transmits power from an engine, which is a driving source, to wheels, and which forms a desired gear stage by changing the engagement states of a plurality of friction engagement elements, a travel range standby control unit that performs a travel range standby control to engage some of the travel range forming elements that form the travel range among the plurality of friction engagement elements before switching to the travel range; a hydraulic oil state determination unit that determines whether or not the viscosity of the hydraulic oil that operates the friction engagement element is in a response delay state that causes a response delay to an instruction value of hydraulic pressure when the travel range standby control is started; With When it is determined that the viscosity of the hydraulic oil is in a response delay state, the travel range standby control unit increases an instruction value of an oil pressure for engaging a brake element included in the travel range forming element from an oil pressure at which the release state of the brake element is maintained after a predetermined standby period has elapsed, in which the oil temperature of the hydraulic oil becomes equal to or higher than a predetermined threshold value and an instruction value of an oil pressure of the hydraulic oil is kept at a state before the start of engagement. Automatic transmission control device.

2. The standby period set when it is determined that the response delay state is present is longer than the standby period set when the travel range standby control is started and the viscosity of the hydraulic oil is in a response tracking state that tracks the hydraulic pressure command value. The automatic transmission control device according to claim 1.

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