Control device for automatic transmission

Abstract

The present application aims to reduce the frequency of control for removing air mixed into a fluid without causing a delay in shifting and the like. A controller that controls shifting of an automatic transmission has: a high responsiveness shift determination section that determines that shifting to a prescribed shift range is a shift for which high responsiveness is required; a low load determination section that determines that a torque capacity required for an engagement mechanism is below a predetermined reference torque; a shift range determination section that determines that a shift range in which the prescribed shift is likely to occur is set; and an air discharge hydraulic pressure control instruction section that instructs air discharge hydraulic pressure control when the determination in the high responsiveness shift determination section and the determination in the low load determination section and the determination in the shift range determination section are all true.

Description

Technical Field

[0001] This invention relates to a control device for a transmission that performs gear shifting by engaging or disengaging a engagement mechanism such as a clutch or brake, and more particularly to a control device for an automatic transmission that performs gear shifting by hydraulic pressure using an electro-hydraulic engagement mechanism. Background Technology

[0002] In such automatic transmissions, it is known that air can get mixed into the hydraulic circuit controlling the engagement mechanism, causing engagement delays and other issues. An example of a control method for removing air mixed into the hydraulic circuit is described in Patent Document 1 or Patent Document 2. In the device described in Patent Document 1, air mixed into the hydraulic circuit is removed by periodically supplying hydraulic pressure to the actuator, specifically to the actuator attached to the engagement mechanism, during the period when the piston is not in motion. In this case, if the control of the hydraulic pressure for removing air overlaps with the gear shift, the change in hydraulic pressure in the engagement mechanism may become larger, resulting in greater impact. Therefore, in the device described in Patent Document 1, the presence of air mixed into the hydraulic circuit is estimated, and the forced supply of hydraulic pressure for removing air is only performed when this estimate is true. Furthermore, the device described in Patent Document 2 is configured to perform pre-charge hydraulic pressure, which is supplied in a manner that prepares the clutch for torque capacity. During the period from the start to the end of the pre-charge hydraulic pressure, air purging control of the oil pump is continuously performed to remove air bubbles from the working oil.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2002-243029

[0004] Patent Document 2: Japanese Patent Application Publication No. 2015-051728 Summary of the Invention

[0005] To remove air mixed into the fluid, as described in Patent Document 1, the hydraulic pressure is increased to a level that does not generate torque capacity when the clutch or other engagement mechanism is released. To minimize overlap between the control of the hydraulic pressure used for air removal and the control of the hydraulic pressure used for transmission, the device described in Patent Document 1 only performs hydraulic control for air removal when air is detected. However, since it is impossible to directly detect air mixing or for the mixed air to affect the engagement delay of the engagement mechanism, the device described in Patent Document 1 indirectly estimates the air mixing based on factors such as the period of hydraulic pressure supply interruption or the temperature of the transmission. Since the air mixing is entirely based on estimation, in practice, hydraulic control for air removal may be performed even when it does not have a significant impact on transmission delay or transmission shock. That is, since the device described in Patent Document 1 is designed for air removal, even when there are no significant obstacles to transmission control, there may be undesirable situations such as excessive or unnecessary execution of hydraulic control for air removal. Furthermore, the hydraulic pressure used to remove air is controlled by applying a low pressure to the engagement mechanism, to a degree that the engagement mechanism does not have torque capacity. If this pressure regulation is performed by, for example, a linear solenoid valve, the valve opening becomes smaller. Therefore, if foreign matter is mixed into the hydraulic pressure, it may engage and cause abnormalities in the pressure regulation. If the pressure regulation for removing air is repeatedly performed as in the device of Patent Document 1, the possibility of foreign matter engaging or abnormalities occurring in the pressure regulation due to this reason increases.

[0006] The present invention was made in view of the above-mentioned technical problems, and its purpose is to provide a control device for an automatic transmission that can reduce the frequency of control for removing air mixed into the fluid without causing obstacles such as shift delay.

[0007] To achieve the above objectives, the present invention provides a control device for an automatic transmission, comprising an engagement mechanism and performing air venting hydraulic control. The engagement mechanism engages by supplying hydraulic pressure to set a predetermined gear. The air venting hydraulic control applies hydraulic pressure to vent air mixed in with fluid supplied to the engagement mechanism when a gear is set to release the engagement mechanism. The control device for the automatic transmission includes a controller for controlling the gear shifting of the automatic transmission. The controller includes: a high-responsiveness shift determination unit that determines that shifting to the predetermined gear requires high responsiveness; and a low-load determination unit that... The system includes: a torque capacity determination unit that determines the required torque capacity for the engagement mechanism is below a predetermined reference torque; a gear shift determination unit that determines that a gear shift that could produce the predetermined gear shift is set; and an air discharge hydraulic control indicator unit that instructs the air discharge hydraulic control unit when the high-response gear shift determination unit determines that shifting to the predetermined gear shift requires high responsiveness, the low-load determination unit determines that the required torque capacity for the engagement mechanism is below a predetermined reference torque, and the gear shift determination unit determines that the predetermined gear shift could be produced and a gear shift that releases the engagement mechanism is set.

[0008] In this invention, the controller further includes a driving mode selection unit that selects a first driving mode and a second driving mode. The first driving mode performs the gear shift based on a first shift point predetermined according to the required driving force and vehicle speed of the vehicle equipped with the automatic transmission. The second driving mode performs the gear shift based on a second shift point set on the side of required driving force or high vehicle speed, which is larger than the first shift point. The high-responsiveness shift determination unit can determine whether the shift to the specified gear is a high-responsiveness shift based on the selection of the second driving mode.

[0009] In this invention, the low load determination unit can determine that the torque capacity required by the engagement mechanism is below a predetermined reference torque based on the throttle opening, which is the amount of throttle pedal depressed when performing acceleration and deceleration operations on a vehicle equipped with the automatic transmission, being below a predetermined value.

[0010] In this invention, the specified gear shift is a downshift to the specified gear, and the gear that the gear shift determination unit determines may produce the specified gear shift can be any gear that is closer to the high-speed side than the specified gear.

[0011] Invention Effects

[0012] In this invention, the timing for performing air discharge hydraulic control to increase hydraulic pressure in order to expel air mixed into the fluid is limited to situations where a specified speed change requires high speed change responsiveness, and the torque capacity required by the engagement mechanism is below the reference torque under low load, and a gear that could potentially produce the specified speed change is provided. Therefore, the frequency or number of times hydraulic control for expelling air mixed into the fluid is reduced. Furthermore, by performing air discharge hydraulic control under conditions requiring high speed change responsiveness, speed change can be performed with high responsiveness without delaying the engagement of the engagement mechanism. Similarly, under low loads with low torque applied to the engagement mechanism, the engagement pressure of the engagement mechanism is low, and since hydraulic control to expel air from the fluid is performed during this speed change, the desired speed change can be performed. When the hydraulic pressure is adjusted to low pressure, foreign objects may engage in the valve used for pressure adjustment; however, in this invention, by reducing the frequency or number of times air discharge hydraulic control is performed, foreign objects engaging in the valve used for pressure adjustment or abnormalities in hydraulic control caused by this can be avoided or suppressed. Attached Figure Description

[0013] Figure 1 This is a skeleton diagram illustrating an example of an automatic transmission in an embodiment of the present invention.

[0014] Figure 2 It is an engagement schedule for setting the engagement or disengagement of engagement mechanisms for each gear.

[0015] Figure 3 This is a block diagram illustrating the functional structure of the controller in an embodiment of the present invention.

[0016] Figure 4 This is a flowchart illustrating an example of control performed in an embodiment of the present invention.

[0017] Figure 5 This is a timing diagram schematically illustrating the changes in driving mode, throttle opening, engine speed, and indicated pressure of the third clutch when the control involved in this invention is applied to a coasting downshift from fourth gear to third gear. Detailed Implementation

[0018] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments described below are merely examples of how to implement the present invention and are not intended to limit the invention.

[0019] First, an example of an automatic transmission in an embodiment of the present invention will be described. Figure 1The automatic transmission shown is mounted on a vehicle and features both a conventionally known dual-pinion planetary gear mechanism (hereinafter referred to as the first planetary gear mechanism 1) and a Lavigno-type planetary gear mechanism (hereinafter referred to as the second planetary gear mechanism 2). This automatic transmission is connected to the output shaft 4 of the engine 3, which serves as the drive power source, via a torque converter (not shown). Furthermore, it is configured to allow setting of forward gears 1 through 8 and reverse gears 1 and 2, and to allow setting of any gear based on the target engine speed or required drive force.

[0020] If we explain in detail Figure 1 The automatic transmission shown has a structure in which the first planetary gear mechanism 1 comprises a first sun gear 6 connected to a fixed part 5 such as a housing, a first internal pinion 7 meshing with the first sun gear 6, a first external pinion 8 meshing with the first internal pinion 7, a first ring gear 9 meshing with the first external pinion 8, and a first gear carrier 11 connected to the input shaft 10 to maintain the rotation and revolution of the first internal pinion 7 and the first external pinion 8. That is, the first planetary gear mechanism 1 is a differential mechanism with three rotational elements. This differential mechanism is configured such that when the engine 3 outputs driving force, the first gear carrier 11 functions as an input element, the first sun gear 6 functions as a reaction force element, and the first ring gear 9 functions as an output element. Furthermore, the first planetary gear mechanism 1 functions as a speed reducer.

[0021] Figure 1 The second planetary gear mechanism 2 shown comprises a second sun gear 12 and a third sun gear 13 arranged concentrically with the input shaft 10, a second inner pinion 14 meshing with the third sun gear 13, a second outer pinion 15 meshing with the second inner pinion 14 and the second sun gear 12, a second carrier 16 that maintains the second inner pinion 14 and the second outer pinion 15 so that they can rotate and revolve, and a second ring gear 17 meshing with the second outer pinion 15. That is, the second planetary gear mechanism 2 is composed of a single-pinion type planetary gear mechanism and a double-pinion type planetary gear mechanism that share the second carrier 16 and the second ring gear 17. Therefore, the second planetary gear mechanism 2 is configured as a differential mechanism having four rotating elements: the second sun gear 12, the third sun gear 13, the second carrier 16, and the second ring gear 17.

[0022] Furthermore, the system includes multiple clutches or brakes that selectively engage the rotating elements of the first planetary gear mechanism 1 and the second planetary gear mechanism 2. Specifically, it includes a first clutch C1 to connect the first ring gear 9 and the third sun gear 13, a second clutch C2 to connect the input shaft 10 or the first wheel carrier 11 and the second wheel carrier 16, a third clutch C3 to connect the first ring gear 9 and the second sun gear 12, and a fourth clutch C4 to connect the first wheel carrier 11 and the second sun gear 12. These clutches C1, C2, C3, and C4 are friction-type engagement mechanisms operated by conventionally known hydraulic actuators. These hydraulic actuators house a piston portion that can move back and forth inside a cylinder, and are configured to change the torque capacity according to hydraulic pressure.

[0023] Furthermore, a first brake B1 is provided to stop the second sun gear 12 by connecting the fixed part 5 (such as the housing) and the second sun gear 12. Similarly, a second brake B2 is provided to stop the second wheel carrier 16 by connecting the fixed part 5 and the second wheel carrier 16. Additionally, in Figure 1 In the example shown, the first brake B1 can be a friction brake that can control the braking force acting on the second sun gear 12 by changing the friction force, i.e., changing the torque capacity, and the second brake B2 can be configured to stop the second wheel carrier 16 by engaging the second wheel carrier 16 with the fixing part 5.

[0024] Furthermore, an electronic control unit (hereinafter referred to as ECU18) for controlling the engine 3 or its various engagement mechanisms is provided. Similar to conventionally known units, the ECU18 is primarily composed of a microcomputer. It is configured to take input signals from sensors (not shown), calculate the control quantity for the engine 3 or its various engagement mechanisms based on the input signals and pre-stored mappings or formulas, and output the calculated control quantity as a control command signal. For example, signals of vehicle speed detected by a vehicle speed sensor and throttle opening detected by a throttle opening sensor are input to the ECU18. The vehicle speed sensor detects the rotational speed or rotational velocity of the output shaft of the automatic transmission, or the rotational speed or rotational velocity of the wheels, as the vehicle speed. The throttle opening sensor detects the amount or angle of the accelerator pedal (not shown) used for vehicle acceleration and deceleration, and its detected value represents the required driving force for the vehicle.

[0025] Furthermore, as is known previously, the ECU18 pre-prepared and stores a gear shift mapping with vehicle speed and throttle opening as parameters, and determines the gear based on the input signals and the gear shift mapping. Then, signals are output to each clutch or brake in the manner of the determined gear shift. At this time, in order to suppress shocks caused by gear shifting, the torque capacity of the engagement mechanism can be controlled according to various conditions.

[0026] A gear shift mapping is a line graph that determines the regions of gear shifts using vehicle speed and throttle opening as parameters. The boundaries of each gear shift region are called shift points, and the lines connecting these shift points are called shift lines. During gear shifting, upshift lines are set to enable upshifts and downshift lines to enable downshifts. These shift points or shift lines are set to meet the vehicle's required driving force or fuel consumption rate (energy efficiency). For example, if the upshift line (the first shift point in this invention) is set on a relatively low vehicle speed side or a low throttle opening side, driving is performed with the engine speed, which serves as the driving force source, suppressed at a low speed, resulting in less fuel consumption. Conversely, if the upshift line (the second shift point in this invention) is set on a relatively high vehicle speed side or a high throttle opening side, driving is performed with the engine speed, which serves as the driving force source, increased, resulting in greater driving force, but also increased fuel consumption. As a gear shift mapping, it is possible to have these mappings for driving at low fuel consumption rates and mappings for driving at high driving force / high fuel consumption rates. The control mode that maps the driving under low fuel consumption based on the former is called Normal Mode (Driving Mode 1), and the control mode that maps the driving under high driving force / high fuel consumption based on the latter is called Sport (or Track) Mode (Driving Mode 2).

[0027] The engagement or disengagement states of each engagement mechanism used to set each gear are summarized in the following table. Figure 2 In the combined worksheet. Additionally, in Figure 2 In this context, "○" indicates that the clutch or brake is engaged, and "-" indicates that the clutch or brake is disengaged. For example... Figure 2As shown, each gear is set by engaging two engagement mechanisms, and shifting between adjacent gears is achieved by releasing one of the engaged engagement mechanisms while the other is engaged, and then engaging the other engagement mechanism. This alternation of engagement and release of engagement mechanisms is accomplished by supplying or releasing hydraulic pressure to each engagement mechanism. In this case, if both engagement and release mechanisms have a certain torque capacity, a so-called gear train lock-up occurs, resulting in a shock. Conversely, if the torque capacity of both engagement and release mechanisms is reduced, the input speed (engine speed) increases when power is on, or decreases excessively when power is off. Furthermore, if a sharp shift occurs due to the engagement and release of the two engagement mechanisms, the drive torque changes drastically, resulting in a shock; conversely, if the engagement and release of the two engagement mechanisms are performed slowly, although a shock is less likely, the shift takes time, resulting in decreased shift responsiveness.

[0028] Here, if we describe the hydraulic device that controls the engagement and disengagement of each engagement mechanism, the hydraulic device can be the same as the hydraulic control device for automatic transmissions in vehicles known in the past. It uses a linear solenoid valve or the like to adjust the hydraulic pressure generated by the hydraulic pump to a linear pressure corresponding to the required driving force, represented by the throttle opening, and supplies or discharges this linear pressure to or from the engagement mechanism at a predetermined time and gradient. The fluid (hydraulic pressure) supplied or discharged to the engagement mechanism is essentially an incompressible fluid; however, during the supply and discharge to the actuator in the engagement mechanism, air inevitably mixes in, and the fluid operates as a compressible fluid, which sometimes causes a deterioration in transmission responsiveness. The control device according to the present invention is configured to perform hydraulic control for discharging air mixed in with the fluid via the aforementioned ECU 18.

[0029] The ECU18 used for this control is equivalent to the controller in the embodiment of the present invention, and the functional structure is illustrated in a block diagram. Figure 3 In the case of air removal from the fluid, the control is performed when a predetermined engagement mechanism is released and a gear shift is possible that engages the predetermined engagement mechanism. Therefore, the ECU 18 includes a gear shift determination unit 18a that determines the set gear. This determination can be performed by inputting a gear shift signal from the transmission control computer that controls the automatic transmission, or it can be performed based on vehicle speed, throttle opening, and gear mapping.

[0030] Furthermore, the ECU 18 includes a driving mode selection unit 18b that selects between a normal mode (or the first driving mode) used during normal driving, which is the vehicle's driving mode or the automatic transmission's control mode, and a sport (or track) mode (or the second driving mode) that generates higher driving force. This driving mode selection can be based on a signal from a selection switch (not shown) or as a result of learning from throttle or brake operations. Therefore, the ECU 18 can be configured to acquire these signals.

[0031] Furthermore, the ECU 18 includes a high-responsiveness shift determination unit 18c to determine if the conditions for hydraulic control, which involves discharging air from the fluid (hydraulic pressure), are met. High-responsiveness shifting refers to shifting gears quickly to improve control responsiveness; for example, it is used when vehicle occupants require agile driving. Therefore, the high-responsiveness shift determination unit 18c can determine if a high-responsiveness shift is required based on the selection of the aforementioned sport (or track) mode (or the second driving mode).

[0032] As another condition, a determination is made that the torque capacity required by the engagement mechanism is below a predetermined reference torque; more specifically, that the hydraulic pressure supplied to the engagement mechanism is low. Therefore, a low-load determination unit 18d is provided in the ECU18 as a determination unit for this determination. This determination can be made, for example, based on the throttle opening, and the determination that the hydraulic pressure supplied to the engagement mechanism is low is established when the throttle opening is below a predetermined value.

[0033] Furthermore, the ECU18 also includes an air discharge hydraulic control indicator 18e. The air discharge hydraulic control is a control that increases hydraulic pressure to discharge air (or air bubbles) mixed in with the fluid, and can be the same control described in Patent Document 1 or Patent Document 2 above. That is, it is a control that, while the engagement mechanism is released, increases the engagement pressure supplied to the engagement mechanism until the engagement mechanism is about to have torque capacity. In the embodiment described here, it is preferable to suppress the impact when downshifting to third gear in a forward gear, therefore, in the presence of... Figure 1 In the automatic transmission with the gear system shown, when any one of the 4th to 6th and 8th gears is set to have the 3rd clutch C3 released and the determinations of the high-responsiveness shift determination unit 18c and the low-load determination unit 18d are met, the air exhaust hydraulic control indicator unit 18e outputs a control command signal to execute the air exhaust hydraulic control.

[0034] refer to Figure 4 and Figure 5 An example of control performed by the aforementioned ECU18 will be described. Figure 4 This is a flowchart used to illustrate an example of control. Figure 5 It is performed during the coasting downshift from 4th to 3rd gear when the 3rd clutch C3 is engaged. Figure 4 The timing diagram is shown under the control conditions. Figure 4 The illustrated process is repeatedly executed at predetermined short intervals when the vehicle is in motion or when the ignition switch is turned on and the vehicle is in a so-called "started" state. First, in step S1, it is determined whether a high-response shift will be performed. This determination can be based on whether the aforementioned Sport (or Track) mode (or the second driving mode) has been selected as the driving mode, or on whether a signal indicating a predetermined high-response shift implementation has been received from the shift control computer not shown in the figure. Figure 5 In the timing diagram, at time t1, when the normal mode (driving mode 1) is selected as the driving mode and the vehicle is in second gear with the throttle engaged, the result of step S1 is "no". In this case, no special control is performed, and the process is temporarily terminated. Figure 4 The process is shown below.

[0035] exist Figure 5 In the example shown, at time t2, while driving in second gear, the driving mode switches to track mode, which requires highly responsive gear shifting. In this case, Figure 4 If the result of the judgment in step S1 is "yes", proceed to step S2 to determine whether the throttle opening is below the specified value. Figure 5 In the example shown, because the so-called throttle is engaged and the throttle opening is greater than the specified value, therefore in Figure 5 At time t2, Figure 4 The result of step S2 is "no". Therefore, at this moment, no special control is implemented, and the process is temporarily terminated. Figure 4 The process is shown below.

[0036] Then, if the vehicle speed increases as... Figure 5 As the engine speed increases as shown, the gear shifts from 2nd to 3rd gear, and control for shifting to 3rd gear begins at a predetermined time t3. For example, control known as initial filling is performed to temporarily increase the hydraulic pressure (indicating pressure) of the 3rd clutch C3 to tighten the clutch clearance, and control is performed to gradually increase the hydraulic pressure to bring the hydraulic actuator stroke to a state just before engagement. Furthermore, when the determination to shift to 3rd gear is established, the engagement pressure (indicating pressure) of the 3rd clutch C3 increases along with the release of the 1st brake B1, which is set to 2nd gear. The 3rd clutch C3 engages without slippage at time t4, thus setting 3rd gear.

[0037] If the vehicle speed (engine speed) gradually increases by pressing the accelerator pedal (not shown), then the judgment of shifting from 3rd to 4th gear is valid. Simultaneously, the hydraulic pressure (indicated pressure) is reduced to release the 3rd clutch C3, and its engagement pressure is gradually increased to engage the 4th clutch C4. Thus, the 3rd clutch C3 is almost completely released at time t5, completing the shift to 4th gear. In this case, the hydraulic pressure (indicated pressure) of the 3rd clutch C3 is almost completely discharged, essentially "0". Therefore, even when shifting to 4th gear, because the throttle is engaged and the throttle opening is greater than the specified value, therefore... Figure 4 The result of step S2 is "no". Therefore, at this moment, no special control is implemented, and the process is temporarily terminated. Figure 4 The process is shown below.

[0038] Then, release the accelerator pedal (not shown), as follows: Figure 5 As shown, the throttle opening decreases towards "0%". At time t6 in this process, the throttle opening falls below a predetermined value, therefore... Figure 4 The result of the judgment in step S2 is "yes". In this case, Figure 4 The process shown proceeds to step S3, which determines whether the vehicle is currently in 4th gear. Figure 5 In the example shown, since the accelerator pedal is pressed back while driving in 4th gear, the result of step S3 is "yes". Since the vehicle speed (engine speed) gradually decreases by releasing the accelerator pedal, a coasting downshift to 3rd gear is predicted.

[0039] If the result of step S3 is "yes", then the prediction is a coasting downshift from 4th to 3rd gear in track mode with the 3rd clutch C3 released. Therefore, in Figure 4 In the process shown, step S4 is initiated, where a command signal is output to implement hydraulic control for air venting, and then the process is temporarily terminated. Figure 4 The process is shown. The air exhaust hydraulic control is as described above. Additionally, if the throttle opening is below a predetermined value while driving in a gear other than 4th gear, the result of the judgment in step S3 is "No," therefore, in this case, no special control is performed, and the process is temporarily terminated. Figure 4 The process.

[0040] exist Figure 5In the example shown, air bleed hydraulic control is executed until the judgment is fulfilled at time t7, indicating a downshift from 4th gear to 3rd gear in track mode. Upon fulfilling the downshift to 3rd gear judgment, a temporarily high hydraulic pressure, known as the initial fill of the 3rd clutch C3, is supplied. Then, after restoring the engagement pressure to the standby pressure, the engagement pressure (indicated pressure) of the 3rd clutch C3 is rapidly increased to the fully engaged hydraulic pressure. In this case, air in the fluid is expelled through the previous air bleed hydraulic control, thus the engagement pressure of the 3rd clutch C3 changes as indicated, achieving rapid gear shifting.

[0041] The aforementioned air exhaust hydraulic control is performed by applying a low hydraulic pressure to a degree where the engagement mechanism has no torque capacity. Furthermore, it is performed when the driving force (engine load) is low, such as when the throttle opening is "0", and the hydraulic pressure (e.g., linear pressure) of the automatic transmission is low. Therefore, the opening of valves such as linear solenoid valves for pressure regulation becomes smaller, potentially leading to foreign matter (contamination) in the valve engagement fluid. However, in the embodiments of the present invention described above, high responsiveness to gear shifting is required, and air exhaust hydraulic control is performed only under low loads. Therefore, it is possible to avoid or suppress valve engagement with foreign matter (contamination) or the resulting abnormal engagement / release of the hydraulic or engagement mechanism.

[0042] Furthermore, the present invention is not limited to the above-described embodiments. The gear that performs the air discharge hydraulic control can be any gear in the engagement mechanism of the release object, and can be a gear on the higher speed side than the fourth gear described above. In other words, it can be a gear that may produce shifting speeds requiring high shifting responsiveness. In the above embodiments, it can be at least any one of the fourth to sixth gears and the eighth gear that may downshift to the third gear. Therefore, in the aforementioned step S4, determining whether any one of the fourth to sixth gears and the eighth gear is set can be used instead of determining whether the fourth gear is set.

[0043] Symbol Explanation

[0044] 1-First planetary gear mechanism, 2-Second planetary gear mechanism, 3-Engine, 4-Output shaft, 5-Fixed part, 6-First sun gear, 7-First internal pinion, 8-First external pinion, 9-First ring gear, 10-Input shaft, 11-First wheel carrier, 12-Second sun gear, 13-Third sun gear, 14-Second internal pinion, 15-Second external pinion, 16-Second wheel carrier, 17-Second ring gear, 18-ECU (controller), 18a-Gear shift determination unit, 18b-Driving mode selection unit, 18c-High responsiveness gear shift determination unit, 18d-Low load determination unit, 18e-Air exhaust hydraulic control indicator unit, B1-First brake, B2-Second brake, C1-First clutch, C2-Second clutch, C3-Third clutch, C4-Fourth clutch.

Claims

1. A control device for an automatic transmission, comprising an engagement mechanism and performing air venting hydraulic control, wherein the engagement mechanism is engaged by supplying hydraulic pressure to set a predetermined gear, and the air venting hydraulic control applies hydraulic pressure to vent air mixed in with a fluid supplied to the engagement mechanism when a gear is set that would release the engagement mechanism, the control device for the automatic transmission being characterized in that it includes a controller for controlling the gear shifting of the automatic transmission. The controller has: The high-response shift determination unit determines that the specified shift to the specified shift gear is a shift that requires high responsiveness; The low-load determination unit determines that the torque capacity required for the engagement mechanism is below a predetermined reference torque. The gear selection unit determines which gear is set to potentially produce the specified gear shift. and The air discharge hydraulic control indicator instructs the air discharge hydraulic control when the high-response shift determination unit determines that shifting to the specified shift gear requires high responsiveness, the low-load determination unit determines that the torque capacity required for the engagement mechanism is below a predetermined reference torque, and the shift gear determination unit determines that the specified shift is possible and a shift gear for releasing the engagement mechanism is set.

2. The control device for an automatic transmission according to claim 1, characterized in that, The controller also includes a driving mode selection unit that selects a first driving mode and a second driving mode. The first driving mode executes the gear shift based on a first shift point predetermined according to the required driving force and vehicle speed of the vehicle equipped with the automatic transmission. The second driving mode executes the gear shift based on a second shift point set on the side of required driving force or high vehicle speed, which is larger than the first shift point. The high-responsiveness shift determination unit determines whether the shift to the specified gear is a high-responsiveness shift based on the selection of the second driving mode.

3. The control device for an automatic transmission according to claim 1 or 2, characterized in that, The low-load determination unit determines that the torque capacity required by the engagement mechanism is below a predetermined reference torque when the throttle opening, which is the amount of throttle pedal depressed during acceleration and deceleration of a vehicle equipped with the automatic transmission, is below a predetermined value.

4. The control device for an automatic transmission according to claim 1 or 2, characterized in that, The specified gear shift refers to downshifting to the specified gear range. The gear determined by the gear selection unit that may produce the specified gear shift is any gear that is closer to the high-speed side than the specified gear shift.

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