JP7670541B2 - Automatic transmission control device - Google Patents

Description

The present invention relates to a control device for an automatic transmission.

An automatic transmission, which is provided in a drive force transmission system between the output shaft of an internal combustion engine and the drive wheels of a vehicle, is configured to form multiple gears with different gear ratios by selectively engaging multiple hydraulically operated friction engagement elements.

When a vehicle equipped with such an automatic transmission is traveling and an operation that reduces the amount of accelerator pedal operation, such as releasing the accelerator, an upshift is performed to prevent a decrease in vehicle speed, etc.

During this upshift, a process is performed to reduce the hydraulic pressure of the disengagement side frictional engagement element that was engaged in the low-speed gear before the upshift and that is released in the high-speed gear after the upshift. In addition, when the upshift is performed, a process is also performed to supply hydraulic pressure to the engagement side frictional engagement element that is engaged in the high-speed gear after the upshift to engage the engagement side frictional engagement element.

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 when the accelerator pedal is decreased, but decreases gradually, resulting in a so-called residual torque.

If there is such residual torque 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 release side frictional engagement element is gradually reduced to suppress the occurrence of shift shock caused by the torque capacity of the release side frictional engagement element being insufficient relative to the remaining torque.

JP 2008-155773 A

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 delays the release of the release side frictional engagement element, which may result in a longer time required for gear shifting.

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

According to this configuration, when it is determined that an upshift is not in progress, the oil pressure of the engaging frictional engagement element is increased until it is determined that an upshift is in progress, thereby increasing the torque capacity of the engaging frictional engagement element. Therefore, the occurrence of shift shock is suppressed by suppressing the shortage of torque capacity relative to the remaining torque. 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 engaging frictional engagement element. Therefore, it is possible to suppress the occurrence of shift shock while preventing the time required for shifting from becoming longer.

In addition, when the control device determines in the determination process 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.

If the oil pressure, which had been increased up until that point, 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 suddenly, which could cause a shock if there was still residual torque. In this regard, the increased oil pressure is gradually reduced to the oil pressure before the increase, which prevents such a sudden drop in 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.

In addition, in the above control device, the determination process may calculate a target value and an actual value for 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 may execute a process to determine 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."

In addition, in the above control device, the determination process may execute a process of determining that an upshift is in progress if the actual value is equal to or greater than a specified threshold value.

FIG. 1 is a diagram showing a configuration of a vehicle according to an embodiment. FIG. 2 is a block diagram showing a process executed by the control device according to the embodiment. 1A is a time chart showing the execution state of an upshift in the same embodiment, FIG. 1B is a time chart showing the change in turbine rotation speed during an upshift, FIG. 1C is a time chart showing the change in hydraulic pressure command value of an engaging side frictional engagement element during an upshift, FIG. 1D is a time chart showing the change in hydraulic pressure command value of a releasing side frictional engagement element during an upshift, FIG. 1E is a time chart showing the change in target shift progress degree during an upshift, and FIG. 1F is a time chart showing the change in actual shift progress degree during an upshift.

<Vehicle configuration>
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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 below with reference to FIGS.

As shown in FIG. 1, the internal combustion engine 10 of the 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 the cylinders. In the 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.

The crankshaft 18, which is the output shaft of the internal combustion engine 10, is connected to the 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 the input shaft 410 of the automatic transmission 400.

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

The automatic transmission 400 is a planetary gear type multi-speed transmission with a well-known structure, and has multiple planetary gear mechanisms and multiple hydraulically operated friction engagement elements 430, which are clutches and brakes. By selectively engaging these friction engagement elements 430, multiple gear stages with different gear ratios are formed.

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 the vehicle 500 are connected.
The friction engagement elements 430 of the automatic transmission 400 and the lock-up clutch 45 are operated 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).

<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.

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

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 ratio 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.

The control device 100 includes a central processing unit (hereafter 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.

When the control device 100 starts supplying hydraulic pressure to the friction 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 friction engagement element 430. By executing this quick apply control, hydraulic oil is quickly supplied to the friction engagement element 430.

In addition, when the accelerator operation amount ACCP decreases to a specified amount or more, the control device 100 suppresses a sudden change in engine torque by executing dashpod control that gradually reduces the opening of the throttle valve 12.

In addition, the control device 100 suppresses a decrease in vehicle speed 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.

The calculation of the hydraulic command value P for the engaging frictional engagement element during an accelerator-off upshift is described below. Note that the engaging frictional engagement element during an accelerator-off upshift is a frictional engagement element that is disengaged in the low-speed gear before the upshift and engaged in the high-speed gear after the upshift.

<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".

When this process is started, first, the CPU 110 judges whether the current upshift is an accelerator-off upshift (S100). Then, when it is judged that the upshift is an accelerator-off upshift (S100: YES), the CPU 110 calculates the target shift progress Rt (S110). The shift progress 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 is calculated as the inertia phase progress, and the shift progress is "0" until the inertia phase starts. When the inertia phase ends, the shift progress is "1". Then, from the start of the inertia phase to the end of it, the shift progress gradually increases from "0" to "1". The target shift progress Rt, which is a control target value for the inertia phase progress, is calculated based on the elapsed time since the start of the upshift, the oil temperature Toil, the output rotation speed Nout, etc.

Next, the CPU 110 calculates the actual progress rate Rr of the gear shift 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 completed (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 if the target shift progress rate Rt calculated in S110 is equal to or greater than a specified threshold value Rtref and the actual shift progress rate 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.

When it is determined in S130 that an upshift is not in progress (S130: YES), the CPU 110 calculates the hydraulic correction amount Pad for the engaging friction engagement element (S150). For example, the CPU 110 calculates the hydraulic correction amount Pad based on the target shift progress rate Rt calculated in S110 such that the value of the hydraulic correction amount Pad increases as the value of the target shift progress rate Rt increases.

Next, the CPU 110 calculates the hydraulic command value Pr for the engaging frictional engagement element (S180). The CPU 110 calculates the hydraulic command value Pr by adding the hydraulic correction amount Pad to the basic hydraulic command value Pb. 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 for 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, etc. Then, the solenoid valve 90a is operated based on this calculated hydraulic command value Pr, thereby controlling the hydraulic pressure of the engaging frictional engagement element. The processes of S150 and S180 constitute a hydraulic pressure increase process that increases the hydraulic pressure of the engaging frictional engagement element.

On the other hand, if a negative judgment is made in S130 (S130: NO), it is judged whether the actual shift progress rate Rr calculated in S120 is equal to or greater than a specified threshold value Rrref (S140). The threshold value Rrref is set to a value that allows accurate judgment that an upshift is in progress based on the actual shift progress rate 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 judgment that an inertia phase has actually started. The processing in S140 also constitutes a judgment process that judges whether an upshift is in progress.

When it is determined that the actual shift progress rate 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 correction amount Pad (S170). In this S170, the CPU 110 calculates a new hydraulic correction amount Pad by subtracting the specified reduction amount Padsw from the current hydraulic correction amount Pad. After executing the process of reducing the hydraulic correction amount Pad in this way, the CPU 110 adds the new hydraulic correction amount Pad to the basic hydraulic command value Pb to calculate the hydraulic command value Pr (S180). The process of S170 and S180, which calculates the hydraulic command value Pr using the hydraulic correction amount Pad calculated in S170, constitutes a hydraulic pressure reduction process that gradually reduces the hydraulic pressure that has been increased until it is determined that an upshift is in progress to the hydraulic pressure before the increase.

When the process of S180 is completed or when a negative determination is made in S100, CPU 110 temporarily ends the series of processes shown in FIG.
<Action>
The operation of this embodiment will now be described.

Figure 3 shows the changes in various values when accelerator off upshift control is executed. Note that 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 hydraulic command value for the engaging frictional engagement element during an upshift, Figure 3(d) shows the change in 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.

When an upshift is started at time t1, the hydraulic command value Pc for the release-side frictional engagement element is first lowered, thereby releasing the release-side frictional engagement element. Note that the release-side frictional engagement element is a frictional engagement element that is engaged in the low-speed gear before the upshift and is released in the high-speed gear after the upshift.

When the release-side frictional engagement element is released, quick apply control is executed between time t2 and time t3. 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 Figure 2 are started.

The target shift progress rate Rt is "0" from the start of the upshift until a specified time has elapsed, and then gradually increases toward "1" after the specified time has elapsed. The actual shift progress rate Rr also gradually changes from "0" to "1" in response to changes in the actual turbine rotation speed NT.

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 increase process is started. This causes the hydraulic pressure command value Pr to gradually increase.

Then, at time t5, when the actual shift progress degree Rr becomes equal to or greater than the threshold value Rrref and it is determined that an upshift is in progress, the hydraulic pressure reduction process is started. As a result, the hydraulic pressure command value Pr gradually decreases toward the basic hydraulic pressure command value Pb, which is the hydraulic pressure before the increase.

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 fully engage the engaging friction engagement element. Then, the upshift ends.

＜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.

(2) If the oil pressure that has been increased up until that point is quickly reduced to the oil pressure before the increase when it is determined that an upshift is in progress, the torque capacity will drop suddenly, which may cause a shock if there is still residual torque. 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 sudden drop in 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.

<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.

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.

The hydraulic pressure reduction process may be omitted. Even in this case, the effects and advantages other than those described above in (2) can be obtained.
The shift progress degree is the progress degree of the inertia phase. However, other progress degrees indicating the progress degree of the shift, for example, the progress degree from the start to the end of the shift, may be used.

The control device 100 is not limited to a device equipped with a CPU 110 and memory 120 and executing software processing. For example, it may be equipped with a dedicated hardware circuit such as an ASIC that performs hardware processing of at least a portion 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) It includes 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) It includes a processing device and program storage device that executes a portion of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices equipped with a processing device and program storage device, and multiple dedicated hardware circuits.

REFERENCE SIGNS LIST 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 wheels 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 (3)

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. 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. 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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