Automatic transmission control device

Abstract

To keep a time necessary for a gear change from being long.SOLUTION: When a gear change command for an up-gear change is issued when an accelerator operation amount of a vehicle has decreased, a control device 100 performs gear change control for supplying hydraulic pressure to an engagement-side friction engagement element which is engaged at a high-speed side gear stage after an up-gear change out of friction engagement elements included in an automatic transmission 400 so as to engage the engagement-side friction engagement element. The control device 100 also performs determination processing for determining whether or not an up-gear change is in progress during the execution of the gear change control, and when it is determined in the determination processing that an up-gear change is not in progress, performs hydraulic pressure increment processing for increasing the hydraulic pressure of the engagement-side friction engagement element until it is determined that an up-gear change is in progress.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] An automatic transmission provided in a driving force transmission system between the output shaft of an internal combustion engine and the drive wheels of a vehicle is configured to form a number of gear stages with different gear ratios by selectively engaging a number of hydraulically operated friction engagement elements.

[0003] When a vehicle equipped with such an automatic transmission is traveling and an operation that reduces the amount of accelerator pedal depression, such as releasing the accelerator, an upshift is performed in order to suppress a decrease in vehicle speed, for example.

[0004] During this upshift, a process is performed to reduce the hydraulic pressure of the release-side frictional engagement element that was engaged in the lower gear before the upshift and that will be released in the higher gear after the upshift. When the upshift is performed, a process is also performed to supply hydraulic pressure to the engagement-side frictional engagement element that will be engaged in the higher gear after the upshift to engage the engagement-side frictional engagement element.

[0005] Generally, when the accelerator pedal is operated to reduce its depression amount, a so-called dashpod control is performed to gradually reduce the opening of the throttle valve. When such dashpod control is performed, the engine torque does not decrease immediately but decreases gradually when the accelerator pedal is decreased, resulting in a so-called residual torque.

[0006] If such residual torque remains during the above-mentioned upshift, there is a risk of shift shock occurring. Therefore, for example, in the device described in Patent Document 1, the hydraulic pressure of the releasing side frictional engagement element is gradually reduced to suppress the occurrence of shift shock caused by the torque capacity of the releasing side frictional engagement element being insufficient relative to the residual torque. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-155773 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, if the oil pressure of the release side frictional engagement element is gradually reduced, the time that oil pressure is supplied to the release side frictional engagement element becomes longer, which may delay the release of the release side frictional engagement element and increase the time required for gear shifting. [Means for solving the problem]

[0009] The control device for an automatic transmission that solves the above problem is provided in a drive force transmission system between an output shaft of an internal combustion engine and drive wheels of a vehicle, and controls an automatic transmission that forms a plurality of gear stages with different gear ratios by selectively engaging a plurality of friction engagement elements that are hydraulically operated. When an upshift command is issued when an accelerator operation amount of the vehicle is reduced, the control device executes a shift control for supplying hydraulic pressure to an engaging-side friction engagement element that is engaged in a higher gear stage after an upshift among the friction engagement elements to engage the engaging-side friction engagement element, and executes a determination process for determining whether an upshift is in progress during the execution of the shift control, and a hydraulic pressure increase process for increasing the hydraulic pressure of the engaging-side friction engagement element until it is determined that an upshift is in progress when the determination process determines that an upshift is not in progress.

[0010] According to this configuration, when it is determined that an upshift is not in progress, the oil pressure of the on-coming frictional engagement element is increased until it is determined that an upshift is in progress, thereby increasing the torque capacity of the on-coming frictional engagement element. Therefore, the shortage of torque capacity relative to the remaining torque is suppressed, thereby suppressing the occurrence of shift shock. Here, in this configuration, the torque capacity is adjusted by changing the magnitude of the oil pressure, rather than lengthening the time that oil pressure is supplied to the on-coming frictional engagement element. Therefore, it is possible to suppress the occurrence of shift shock while preventing the time required for shifting from becoming longer.

[0011] In addition, in the above control device, when the judgment process determines that an upshift is in progress, a hydraulic pressure reduction process may be executed to gradually reduce the hydraulic pressure that was increased until it was determined that an upshift is in progress to the hydraulic pressure before the increase.

[0012] If the oil pressure, which had been increased until then, were to be quickly reduced to the oil pressure before the increase when it was determined that an upshift is in progress, the torque capacity would drop sharply, and if there was still torque remaining, a shock could occur. In this regard, the increased oil pressure is gradually reduced to the oil pressure before the increase, which prevents such a sharp drop in the torque capacity. Therefore, even if there is still torque remaining after it is determined that an upshift is in progress, it is possible to prevent the occurrence of a shift shock.

[0013] In addition, in the above control device, the judgment process may calculate a target value and an actual value for the degree of progress of up-shifting, which indicates the degree of progress of up-shifting and whose value increases according to the elapsed time after the start of up-shifting, and execute a process to determine that up-shifting is not progressing when the target value is equal to or greater than a specified threshold value and the actual value is "0."

[0014] In the above control device, the determination process may execute a process of determining that an upshift is in progress when the actual value is equal to or greater than a specified threshold value. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a configuration of a vehicle according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a process executed by a control device according to the embodiment. [Diagram 3] FIG. 1 is a time chart showing (a) the execution state of an upshift in the same embodiment, (b) the change in turbine rotation speed during an upshift, (c) the change in hydraulic pressure command value of an engaging side frictional engagement element during an upshift, (d) the change in hydraulic pressure command value of a releasing side frictional engagement element during an upshift, (e) the change in target shift progress rate during an upshift, and (f) the change in actual shift progress rate during an upshift. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Vehicle configuration> Hereinafter, one embodiment of a control device for an automatic transmission provided in a driving force transmission system between an output shaft of an internal combustion engine and driving wheels of a vehicle will be described with reference to Figs. 1 to 3.

[0017] 1, an internal combustion engine 10 installed in a vehicle 500 includes an intake passage 11, a throttle valve 12 provided in the intake passage 11, and a fuel injection valve 13 that supplies fuel to a cylinder. In a combustion chamber of the internal combustion engine 10, a mixture of intake air and fuel injected from the fuel injection valve 13 is combusted to obtain engine output.

[0018] The crankshaft 18, which is the output shaft of the internal combustion engine 10, is connected to an input shaft 41 of a torque converter 42 having a lock-up clutch 45. The output shaft of the torque converter 42 is connected to an input shaft 410 of an automatic transmission 400.

[0019] The torque converter 42 includes a pump impeller 42P connected to the input shaft 41, and a turbine impeller 42T connected to an input shaft 410 of the automatic transmission 400. In the torque converter 42, torque is transmitted between the pump impeller 42P and the turbine impeller 42T via an ATF (Automatic Transmission Fluid), thereby transmitting torque between the input shaft 41 and the output shaft of the torque converter 42.

[0020] The automatic transmission 400 is a planetary gear type multi-stage transmission having a well-known structure, and has a plurality of planetary gear mechanisms and a plurality of hydraulically operated friction engagement elements 430, which are clutches and brakes. A plurality of gear stages with different gear ratios are formed by selectively engaging these friction engagement elements 430.

[0021] An output shaft 420 of the automatic transmission 400 is connected to a differential gear 60. To the output shaft of the differential gear 60, driving wheels 65 of a vehicle 500 are connected. The operation of the friction engagement element 430 of the automatic transmission 400 and the operation of the lock-up clutch 45 are performed by controlling a plurality of solenoid valves 90a provided in a hydraulic control circuit 90 to which hydraulic oil is supplied from an oil pump (not shown).

[0022] <Regarding the control device 100> The control device 100 controls the internal combustion engine 10 and operates various operating parts of the internal combustion engine 10 to control the torque, exhaust component ratio, and other controlled variables. The control device 100 also controls the hydraulic control circuit 90 that controls the lock-up clutch 45 and the automatic transmission 400 and operates a solenoid valve 90a to control the hydraulic pressure, which is a controlled variable.

[0023] When controlling the above-mentioned controlled variables, the control device 100 refers to an output signal Scr of a crank angle sensor 70 that detects a rotation angle of the crankshaft 18. The control device 100 also refers to an intake air amount GA of the internal combustion engine 10 that is detected by an air flow meter 71, and an accelerator operation amount ACCP that is an amount of depression of an accelerator pedal that is detected by an accelerator position sensor 72. The control device 100 also refers to an oil temperature Toil that is the temperature of the above-mentioned hydraulic oil that is detected by an oil temperature sensor 73, and an output rotation speed Nout that is the rotation speed of an output shaft 420 of the automatic transmission 400 that is detected by a rotation speed sensor 74. The control device 100 also refers to a turbine rotation speed NT that is the rotation speed of a turbine impeller 42T that is detected by a rotation speed sensor 75.

[0024] The control device 100 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 70. The control device 100 also calculates the engine load factor KL based on the engine speed NE and the intake air amount GA. The control device 100 also calculates the vehicle speed SP of the vehicle 500 based on the output rotation speed Nout.

[0025] The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110 and a memory 120 in which control programs and data are stored. The CPU 110 executes the programs stored in the memory 120 to control various control variables.

[0026] When starting hydraulic pressure supply to the frictional engagement element 430 of the automatic transmission 400 to which hydraulic pressure supply has been stopped, the control device 100 executes a well-known quick apply control that temporarily increases the hydraulic pressure supplied to the frictional engagement element 430. By executing this quick apply control, the hydraulic oil is quickly supplied to the frictional engagement element 430.

[0027] Furthermore, when the accelerator operation amount ACCP decreases to a specified amount or more, the control device 100 executes dashpod control for gradually decreasing the opening of the throttle valve 12, thereby suppressing a sudden change in engine torque.

[0028] Moreover, the control device 100 suppresses a decrease in vehicle speed, etc., by performing an upshift in response to a decrease in the accelerator operation amount ACCP. Hereinafter, an upshift in response to a decrease in the accelerator operation amount ACCP is referred to as an accelerator-off upshift.

[0029] The calculation of the hydraulic pressure command value P for the on-coming frictional engagement element during an accelerator-off upshift will be described below. Note that the on-coming frictional engagement element during an accelerator-off upshift is a frictional engagement element that is disengaged in a lower gear before the upshift and is engaged in a higher gear after the upshift.

[0030] <About the flowchart> Fig. 2 shows the process executed by the control device 100. The process shown in Fig. 2 is realized by the CPU 110 repeatedly executing a program stored in the memory 120, for example, at a predetermined cycle. This process is started when a shift command for upshifting is issued and the quick apply control is completed. In the following, the step number of each process is represented by a number preceded by "S".

[0031] When this process is started, first, the CPU 110 judges whether or not the current upshift is an accelerator-off upshift (S100). When it is judged that the upshift is an accelerator-off upshift (S100: YES), the CPU 110 calculates a target shift progress degree Rt (S110). The shift progress degree is a value indicating the degree of progress of the upshift, and is a value that increases according to the elapsed time after the start of the upshift. More specifically, in this embodiment, the shift progress degree is calculated as the inertia phase progress degree, and the shift progress degree is "0" until the inertia phase starts. When the inertia phase ends, the shift progress degree is "1". Then, the shift progress degree gradually increases from "0" to "1" from the start to the end of the inertia phase. The target shift progress degree Rt, which is a control target value related to the inertia phase progress degree, is calculated based on the elapsed time from the start of the upshift, the oil temperature Toil, the output rotation speed Nout, and the like.

[0032] Next, the CPU 110 calculates the actual shift progress rate Rr based on the following equation (1) (S120). Rr = (NTbf - NT) / ( NTbf -NTtg)…(1) Rr: Actual shift progress NTbf: Turbine rotation speed before upshift starts NT NT: Current turbine rotation speed NTtg: Turbine rotation speed NT after upshifting is complete (synchronous rotation speed) Next, the CPU 110 executes a determination process to determine whether or not an upshift is in progress (S130). In the determination process of S130, the CPU 110 determines that an upshift is not in progress when the target shift progress degree Rt calculated in S110 is equal to or greater than a specified threshold value Rtref and the actual shift progress degree Rr calculated in S120 is "0". Note that the threshold value Rtref is a value greater than "0" and is set to a value suitable for determining that an upshift is not in progress.

[0033] When it is determined in S130 that an upshift is not in progress (S130: YES), the CPU 110 calculates a hydraulic pressure correction amount Pad for the on-coming frictional engagement element (S150). For example, the CPU 110 calculates the hydraulic pressure correction amount Pad based on the target shift progress degree Rt calculated in S110 such that the value of the hydraulic pressure correction amount Pad increases as the value of the target shift progress degree Rt increases.

[0034] Next, the CPU 110 calculates the hydraulic command value Pr of the on-coming frictional engagement element (S180). The CPU 110 calculates a value obtained by adding the hydraulic correction amount Pad to the basic hydraulic command value Pb as the hydraulic command value Pr. The basic hydraulic command value Pb is calculated based on the drive torque command value Trq* and the oil temperature Toil. The drive torque command value Trq* is a command value of the torque to be applied to the driving wheels 65, and is calculated separately by the control device 100 based on the accelerator operation amount ACCP and the like. The solenoid valve 90a is operated based on the calculated hydraulic command value Pr to control the hydraulic pressure of the on-coming frictional engagement element. The processes of S150 and S180 constitute a hydraulic pressure increasing process for increasing the hydraulic pressure of the on-coming frictional engagement element.

[0035] On the other hand, when a negative determination is made in S130 (S130: NO), it is determined whether or not the actual shift progress degree Rr calculated in S120 is equal to or greater than a prescribed threshold value Rrref (S140). The threshold value Rrref is set to a value that allows accurate determination that an upshift is in progress based on the actual shift progress degree Rr being equal to or greater than the threshold value Rrref. More specifically, in this embodiment, the threshold value Rrref is set to a value that allows accurate determination that an inertia phase has actually started. The process of S140 also constitutes a determination process that determines whether or not an upshift is in progress.

[0036] Then, when it is determined that the actual shift progress degree Rr is less than the threshold value Rrref (S140: YNO), the CPU 110 executes the processes of S150 and S180 described above. On the other hand, when it is determined in S140 that the actual shift progress degree Rr is equal to or greater than the specified threshold value Rrref (S140: YES), the CPU 110 executes a process of reducing the hydraulic pressure correction amount Pad (S170). In this S170, the CPU 110 calculates a new hydraulic pressure correction amount Pad by subtracting the specified reduction amount Padsw from the current hydraulic pressure correction amount Pad. After executing the process of reducing the hydraulic pressure correction amount Pad in this way, the CPU 110 adds the new hydraulic pressure correction amount Pad to the basic hydraulic pressure command value Pb to calculate the hydraulic pressure command value Pr (S180). The process of S170 and S180 for calculating the hydraulic pressure command value Pr using the hydraulic pressure correction amount Pad calculated in S170 constitutes a hydraulic pressure reduction process for gradually reducing the hydraulic pressure that has been increased until it is determined that an upshift is progressing to the hydraulic pressure before the increase.

[0037] Then, when CPU 110 has finished the process of S180 or when a negative determination is made in S100, CPU 110 temporarily ends the series of processes shown in FIG. <effect> The operation of this embodiment will now be described.

[0038] Figure 3 shows the changes in various values ​​when accelerator-off upshift control is executed. Figure 3(a) shows the execution state of an upshift, Figure 3(b) shows the change in turbine rotation speed during an upshift, Figure 3(c) shows the change in the hydraulic command value for the engaging frictional engagement element during an upshift, Figure 3(d) shows the change in the hydraulic command value for the releasing frictional engagement element during an upshift, Figure 3(e) shows the change in the target degree of shift progress during an upshift, and Figure 3(f) shows the change in the actual degree of shift progress during an upshift.

[0039] When the upshift is started at time t1, first, the hydraulic command value Pc of the release-side frictional engagement element is reduced to release the release-side frictional engagement element. Note that the release-side frictional engagement element is a frictional engagement element that is engaged in a lower gear before the upshift and is released in a higher gear after the upshift.

[0040] When the releasing-side frictional engagement element is released, the quick apply control is executed between time t2 and time t3. Then, when this quick apply control ends, the hydraulic pressure command value Pr becomes the basic hydraulic pressure command value Pb, and the series of processes shown in FIG. 2 is started.

[0041] The target shift progress degree Rt is "0" from the start of upshifting until a specified time has elapsed, and after the specified time has elapsed, it gradually increases toward "1." The actual shift progress degree Rr gradually changes from "0" to "1" in accordance with changes in the actual turbine rotation speed NT.

[0042] At time t4, when it is determined that an upshift is not in progress because the target shift progress degree Rt is equal to or greater than the threshold value Rtref and the actual shift progress degree Rr is "0", the hydraulic pressure correction amount Pad is calculated and the hydraulic pressure increasing process is started, whereby the hydraulic pressure command value Pr gradually increases.

[0043] Then, at time t5, when it is determined that an upshift is in progress because the actual shift progress degree Rr is equal to or greater than the threshold value Rrref, a hydraulic pressure reduction process is started, whereby the hydraulic pressure command value Pr is gradually reduced toward the basic hydraulic pressure command value Pb, which is the hydraulic pressure before the increase.

[0044] At time t6, when the turbine rotation speed NT reaches the synchronous rotation speed NTtg, the hydraulic pressure command value Pr is increased toward the specified hydraulic pressure Pk in order to completely engage the on-coming frictional engagement element, and the upshift is then completed.

[0045] <Effects> The effects of this embodiment will be described. (1) When it is determined that an upshift is not in progress, a hydraulic pressure increase process is executed to increase the hydraulic pressure of the on-coming frictional engagement element until it is determined that an upshift is in progress, thereby increasing the torque capacity of the on-coming frictional engagement element. This reduces the shortage of torque capacity relative to the remaining torque, thereby reducing the occurrence of shift shock. Here, the torque capacity is adjusted by changing the magnitude of hydraulic pressure, rather than lengthening the time that hydraulic pressure is supplied to the on-coming frictional engagement element. This makes it possible to reduce the occurrence of shift shock while preventing the time required for shifting from becoming longer.

[0046] (2) If the oil pressure that has been increased up until that point is quickly reduced to the oil pressure before the increase due to a determination that an upshift is in progress, the torque capacity will drop sharply, and if there is still residual torque, a shock may occur. In this regard, in this embodiment, the oil pressure reduction process described above is executed to gradually reduce the increased oil pressure to the oil pressure before the increase. This prevents such a sharp drop in the torque capacity. Therefore, even if there is still residual torque after it is determined that an upshift is in progress, it is possible to prevent the occurrence of a shift shock.

[0047] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0048] The target shift progress rate Rt and the actual shift progress rate Rr may be calculated in other ways. The hydraulic correction amount Pad may be calculated in another manner. Whether or not an upshift is in progress may be determined in another manner.

[0049] The above-described hydraulic pressure reduction process may be omitted. Even in this case, the effects and advantages other than those described in (2) above can be obtained. The degree of shift progress was the degree of progress of the inertia phase, but it may be another degree of progress indicating the degree of shift progress, for example, the degree of progress from the start of shifting to the end of shifting.

[0050] The control device 100 is not limited to a device equipped with a CPU 110 and a memory 120 and executing software processing. For example, a dedicated hardware circuit such as an ASIC may be provided for performing hardware processing of at least a part of what was processed by software in the above embodiment. That is, the execution device may have any of the following configurations (a) to (c). (a) A processing device that executes all of the above processing according to a program, and a program storage device such as a ROM that stores the program. (b) A processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices equipped with a processing device and a program storage device, and a dedicated hardware circuit. [Explanation of symbols]

[0051] 10. Internal combustion engine 11...Intake passage 12...Throttle valve 13...Fuel injection valve 18…Crankshaft 41...Input shaft 42...Torque converter 42P…Pump impeller 42T...Turbine impeller 45…Lock-up clutch 60…Differential gear 65…Drive wheel 70...Crank angle sensor 71...Air flow meter 72...Accelerator position sensor 73...Oil temperature sensor 74, 75...Rotational speed sensor 90...Hydraulic control circuit 90a…Solenoid valve 100...Control device 400…Automatic transmission 430...Friction engagement element 500…Vehicle

Claims

1. A device for controlling an automatic transmission that is provided in a driving force transmission system between an output shaft of an internal combustion engine and drive wheels of a vehicle, and that forms a plurality of gear stages with different gear ratios by selectively engaging a plurality of hydraulically operated friction engagement elements, When an upshift command is issued when an accelerator operation amount of the vehicle is decreased, a shift control is executed to supply hydraulic pressure to an engagement side friction engagement element that is engaged in a higher gear stage after an upshift among the friction engagement elements, thereby engaging the engagement side friction engagement element, and a determination process for determining whether or not an upshift is in progress during execution of the shift control; when it is determined in the determination process that an upshift is not in progress, a hydraulic pressure increase process is executed to increase the hydraulic pressure of the engaging side friction engagement element until it is determined that an upshift is in progress; When it is determined in the determination process that an upshift is in progress, a hydraulic pressure reduction process is executed to gradually reduce the hydraulic pressure that was increased until it was determined that an upshift is in progress to the hydraulic pressure before the increase. An automatic transmission control device.

2. A device for controlling an automatic transmission that is provided in a driving force transmission system between an output shaft of an internal combustion engine and drive wheels of a vehicle, and that forms a plurality of gear stages with different gear ratios by selectively engaging a plurality of hydraulically operated friction engagement elements, When an upshift command is issued when an accelerator operation amount of the vehicle is decreased, a shift control is executed to supply hydraulic pressure to an engagement side friction engagement element that is engaged in a higher gear stage after an upshift among the friction engagement elements, thereby engaging the engagement side friction engagement element, and a determination process for determining whether or not an upshift is in progress during execution of the shift control; when it is determined in the determination process that an upshift is not in progress, a hydraulic pressure increase process is executed to increase the hydraulic pressure of the engaging side friction engagement element until it is determined that an upshift is in progress; The determination process calculates a target value and an actual value of the degree of progress of upshifting, which is a value indicating the degree of progress of upshifting and increases according to the elapsed time after the start of upshifting, and executes a process of determining that upshifting is not progressing when the target value is equal to or greater than a specified threshold value and the actual value is "0." An automatic transmission control device.

3. The determination process executes a process of determining that an upshift is in progress when the actual value is equal to or greater than a specified threshold value. The control device for an automatic transmission according to claim 2.

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