JPH04366063A - Controller for automatic transmission - Google Patents

Abstract

PURPOSE:To reduce shift shock by detecting a friction element coupling start point at the time of shift action accompanying vehicle starting, conducting oil flow control at a hydraulic piston inoperative stroke action sphere before coupling start, and conducting hydraulic control at a torque coupling sphere after coupling start. CONSTITUTION:During vehicle operation, a control unit 5 inputs a torque converter 2 pump impeller rotation pulse 51, a turbine rotation pulse 52, an auxiliary transmission 3 output shaft rotation pulse 53, a shift range signal 54 and a throttle opening signal 55. And on the basis of these input information pieces, a shift step suitable for a vehicle travel condition is decided, and a hydraulic control signal 56 necessary for shift step transfer is outputted to a solenoid valve in a hydraulic control device 4. In this instance, the coupling start point of the torque converter 2 is detected at the time of shift action accompanying vehicle starting, and arrangement is made so that oil flow control may be conducted at a hydraulic piston inoperative stroke action sphere before detection start and hydraulic control may be conducted at a torque coupling sphere after coupling start.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a hydraulic automatic transmission that quickly and smoothly connects hydraulic friction elements.

0002

[Prior Art] A generally known automatic transmission for automobiles is equipped with a shift lever (shift switching means) operated by a driver, a vehicle speed detection sensor, and a throttle opening (engine load) sensor. Depending on the position, the gear stage is automatically switched in relation to the vehicle speed, throttle opening, etc.

Conventionally, in the automatic transmission for automobiles as described above, when the shift lever is operated from the neutral to the drive position (N-D shift) by the driver, the planetary gear transmission mechanism of the transmission is shifted to the first position. It is known that the transmission is temporarily caused to go through a gear other than the first gear, which has a smaller gear ratio, before shifting to the second gear, thereby preventing the occurrence of shock due to sudden transmission of torque.

[0004] Furthermore, this shift control was further improved, and one friction element was connected in advance when the shift lever was in the neutral position so that gears other than first gear could be smoothly obtained. This method is already known (Japanese Patent Application Laid-open No. 78845/1983).

[0005]

[Problems to be Solved by the Invention] Since the conventional automatic transmission control device is configured as described above, during an N-D shift, it is necessary to shift gears other than the first gear before achieving the first gear. The shift time will be longer, as the
This may impair responsiveness when starting.

[0006] In order to avoid this, if one attempts to directly achieve the first gear during the N-D shift, it is possible to minimize the time required to fill the oil into the hydraulic piston cylinder during the preparation period for coupling the hydraulic friction elements. It is necessary to control with high precision the oil flow rate control to perform this and the hydraulic control to prevent the occurrence of shock due to the rapid transmission of torque during connection.

[0007] If these controls are inappropriate, there are problems such as prolongation of shift time and occurrence of abnormal shock during coupling.

[0008] This invention was made to solve the above-mentioned problems, and it is possible to directly shift the gear position of the transmission to first gear when shifting from N-D when starting a car, and The object of the present invention is to obtain a control device for an automatic transmission that can quickly and smoothly transmit torque.

[0009]

[Means for Solving the Problems] A control device for an automatic transmission according to the invention of claim 1 calculates a speed ratio between an input shaft rotational speed and an output shaft rotational speed of a torque converter, and based on this speed ratio. A control unit is provided that detects the coupling start point of the hydraulic friction elements and controls the oil flow rate into the hydraulic piston cylinder and the hydraulic pressure during the preparation period for coupling the hydraulic friction elements.

[0010] The automatic transmission control device according to the invention of claim 2 determines the speed ratio and difference between the input shaft rotational speed and the output shaft rotational speed of the torque converter, calculates acceleration from this difference, and calculates the speed. A control unit is provided that detects the start of coupling of the hydraulic friction elements when the ratio is below a predetermined value and the acceleration is negative, and controls the oil flow rate to the hydraulic piston cylinder and the hydraulic pressure during the preparation period for coupling the hydraulic friction elements. It is something that

The automatic transmission control device according to the third aspect of the invention calculates the discharge flow rate of the electro-hydraulic conversion valve during a hydraulic piston stroke accompanying the coupling operation of the hydraulic friction elements from the drive signal of the electro-hydraulic conversion valve. This system is equipped with a control unit that corrects the oil amount in response to changes in line pressure and oil temperature.

[0012] The control device for an automatic transmission according to the invention of claim 4 provides a hydraulic piston cylinder volume necessary for stroke and coupling operation of the hydraulic piston of the hydraulic friction element. A control unit is provided that learns the piston cylinder volume by calculating from the integrated value of the flow rate discharged by the electrohydraulic conversion valve from the start of filling until the start of coupling of the hydraulic friction is detected.

[0013] The automatic transmission control device according to the invention of claim 5 provides an electric transmission based on a learned value of the hydraulic piston cylinder volume when starting to fill oil into the hydraulic piston cylinder when the hydraulic friction elements are coupled. A control unit is provided that controls the oil pressure conversion valve to set the discharge time at the maximum flow rate and start filling the oil.

The control device for an automatic transmission according to the sixth aspect of the invention is such that the hydraulic control device controls the hydraulic pressure so that the rotational acceleration of the torque converter output shaft coincides with a predetermined target value after the start of coupling of the hydraulic friction elements is detected. It is equipped with a control unit that feeds back control signals.

[0015]

[Operation] The control unit according to the invention of claim 1 controls the torque when controlling the coupling operation of the hydraulic friction elements according to the range selected for the N-D shift by the shift switching means operated by the driver. The input shaft rotational speed and output shaft rotational speed of the converter are detected and the speed ratio between the two is determined. Based on this speed ratio, the coupling start point of the hydraulic friction element is detected, and the coupling start point of the hydraulic friction element is determined. Controls the oil flow rate and oil pressure supplied to the hydraulic piston cylinder during the preparation period.

[0016] The control unit in the invention of claim 2 includes:
When the shift switching means operated by the driver controls the coupling operation of the hydraulic friction element according to the range selected for the N-D shift, the speed between the input shaft rotation speed and the output shaft rotation speed of the torque converter is determined. In addition to finding the ratio, find the difference between the input shaft rotational speed and the output shaft rotational speed, calculate the acceleration from this difference, and when the speed ratio is less than a predetermined value and the acceleration is negative, the hydraulic friction element The start of coupling is detected and the oil flow rate and oil pressure supplied to the hydraulic piston cylinder are controlled during the preparation period for coupling of the hydraulic friction elements.

[0017] The control unit according to the invention of claim 3 includes:
The discharge flow rate of the electro-hydraulic conversion valve during the hydraulic piston stroke associated with the coupling operation of the hydraulic friction elements is calculated from the drive signal of the electro-hydraulic conversion valve, and the calculated discharge flow rate adjusts the hydraulic pressure in response to changes in line pressure and oil temperature. Controls the oil flow to the piston.

[0018] The control unit in the invention of claim 4 includes:
Calculate the integrated value of the flow rate discharged by the electro-hydraulic conversion valve from the time oil starts filling into the piston cylinder of the hydraulic friction element until the start of coupling of the hydraulic friction element is detected, and calculate the piston cylinder volume. By learning, the volume of the hydraulic piston cylinder required to stroke and engage the hydraulic piston of the hydraulic friction element is known.

[0019] The control unit in the invention of claim 5 includes:
Between the start of filling the hydraulic friction element into the hydraulic piston cylinder and the detection of the start of coupling of the hydraulic friction element,
The piston cylinder volume is learned from the integrated flow rate discharged by the electro-hydraulic conversion valve, and based on the learned value, the discharge time at the maximum flow rate of the electro-hydraulic conversion valve is set, and filling of oil into the hydraulic piston cylinder is started. and controls the hydraulic friction elements to perform a coupled operation.

[0020] The control unit according to the invention of claim 6 includes:
After detecting the start of engagement of the hydraulic friction elements, a hydraulic control signal is fed back to the hydraulic control device so that the rotational acceleration of the output shaft of the torque converter matches a predetermined target value.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a control device for an automatic transmission according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of essential parts of one embodiment. In FIG. 1, 1 is an engine, and 2 is an input element (
This is a torque converter that rotates internal hydraulic oil with a pump impeller (hereinafter referred to as a pump impeller) 21, and uses this hydraulic oil to rotate an output element (hereinafter referred to as a turbine runner) 22 while increasing torque under a reaction force from a stator (not shown).

3, the shaft connected to the turbine runner 22 of the torque converter 2 is used as a converter input shaft 31, and the shaft that transmits power to the tires is used as a converter output shaft 32, providing a gear ratio according to the running condition of the vehicle. It is an auxiliary transmission.

Reference numeral 4 denotes a hydraulic control device for controlling the hydraulic pressure supplied to a hydraulic friction element (not shown) within the auxiliary transmission 3.

5 is an input signal to the torque converter 2.
Pump impeller rotation pulse 51, turbine runner rotation pulse 52, and auxiliary transmission output shaft rotation pulse 53 signals detected from gears and electromagnetic pickups (not shown), and a plurality of switches that close at selected positions of the shift lever. A shift range signal 54 for detecting the open/closed position of the accelerator pedal, and a throttle opening that is connected to the accelerator pedal and converts the engine throttle opening amount, which changes depending on the amount of pedal depression, into a voltage value using a potentiometer, and detects the throttle opening. A signal 55 is input, a gear stage suitable for the driving condition of the vehicle is determined based on this information, and a hydraulic control signal 56 necessary for shifting the gear stage is outputted to a hydraulic control signal 56 (not shown) in the hydraulic control device 4. This is a control unit whose main component is a microcomputer that outputs output to a solenoid valve as an electro-hydraulic conversion valve.

FIG. 2 is a schematic diagram of an auxiliary transmission 3 with three forward speeds using a double pinion planetary gear set.

In FIG. 2, reference numeral 20 indicates an engine crankshaft (hereinafter referred to as an input shaft) which is driven by the engine and rotates integrally with the pump impeller 21 of the torque converter 2, and 31 indicates a turbine runner 22 of the torque converter 2.
It is also the output shaft of the torque converter that rotates integrally with the auxiliary transmission 3 and transmits the driving force to the auxiliary transmission 3, and is also the input shaft of the auxiliary transmission, and is hereinafter referred to as the output shaft.

33 is a double pinion type planetary gear set, and this planetary gear set 33 includes a forward sun gear 34, a reverse sun gear 35, and a ring gear 3.
6, a short pinion 37, a long pinion 38, and a carrier 39.

The forward sun gear 34 is connected to the output shaft 31 of the torque converter 2 through a rear clutch C2, and the reverse sun gear 35 is connected to an output shaft 31 of the torque converter 2 through a front clutch C1.

[0029] B1 is a low reverse brake; B1 is a low reverse brake;
2 is the second brake, 3C is the transmission case, the low reverse brake B1 fixes and releases the carrier 39 to the case 3C, and the second brake B2
fixes and releases the reverse sun gear 35 to and from the case 3C. The ring gear 36 is coupled to the output shaft 32 of the auxiliary transmission 3.

FIG. 3 is a block diagram of the hydraulic control circuit of this automatic transmission, and 40 in the figure is an oil pump provided on the crankshaft 20 of the engine 1.

41 is a pressure regulator valve for regulating the oil pressure generated by the oil pump 40 to a constant line pressure; 42 is a shift control valve that is directly connected to the shift lever; 43 to 45 are low reverse brakes B1; This is a duty solenoid valve for controlling the hydraulic pressure supplied to the second brake B2 and the front clutch C1, for example, by duty control.

C2 is the rear clutch described in FIG. 2 above,
When moving forward, hydraulic pressure is supplied through the shift control valve and the vehicle is in the engaged state.

The combination of engagement operations of the friction elements in each gear stage is such that the rear clutch C2 is engaged when moving forward, the low reverse brake B1 is engaged in 1st gear, the second brake B2 is in 2nd gear, and the front clutch C1 is engaged in 3rd gear.
becomes a connected state.

Furthermore, when reversing the vehicle, the front clutch C1 and the low reverse brake B1 are engaged.

Next, the operation of the N-D shift will be explained with reference to the flowcharts of FIGS. 4 and 5 and the time chart of FIG. 6.

FIG. 4 is a main flowchart of the processing of the control unit 5. In step S1, the shift lever position operated by the driver is determined by the shift range signal 54.
In step S2, the throttle opening amount is read, and in step S3, gears (not shown) provided on the input shaft 20, output shaft 31 of the torque converter 2, and output shaft 32 of the auxiliary transmission 3 are detected. Each axis rotation pulse 5 detected from the configuration with the electromagnetic pickup
1 to 53, the control unit 5 measures the average pulse period at each fixed sampling period, and calculates the engine rotation speed (input shaft rotation speed of the torque converter 2) NE, turbine rotation speed (output shaft rotation speed of the torque converter 2) NT,
The output shaft rotational speed (corresponding to vehicle speed) NO of the auxiliary transmission 3 is calculated.

Next, in step S4, the input shaft rotational speed NE of the torque converter 2 obtained in step S3,
A speed ratio E (=NT/NE) of the torque converter 2 is calculated based on the output shaft rotational speed NT.

In step S5, it is determined based on the shift lever position whether the drive shaft of the transmission is in the neutral state or in the running state. For example, the vehicle is stopped and the shift lever is moved to N or P (parking). When the range is set, the process advances to step S6, and in step S6, the solenoid valves 43 to 45 are kept fully closed.

When the shift lever is in the N or P range, the shift control valve 42, which operates by being directly connected to the shift lever, cuts off the supply of hydraulic pressure to each friction element, so the drive shaft is in the neutral state. Become.

On the other hand, if the driver operates the shift lever to a position other than the N or P range in order to start the car, the process proceeds to step S7, in which it is determined whether the type of shift is an N-D shift, If it is not an ND shift, processing related to other shifts is performed in step S8.

Further, if the N-D shift is selected in step S7, step S
The process advances to step S9, and an ND shift is executed in step S9.

FIG. 5 shows an execution flowchart for directly achieving the first speed during the N-D shift. In FIG. 5, in step S10, the shift process is determined based on the phase value, and processing is performed for each phase. When the N-D shift command is issued, the phase is 0, and steps S11 to S
Processing No. 14 is performed only once.

In step S11, in preparation for the engagement of the low reverse brake B1, the discharge flow rate QLR of the valve is set to the maximum flow rate Q1 to fill oil into the brake piston cylinder. Based on the learned value Vr of the piston cylinder volume, the filling time tf of oil into the piston cylinder when the valve is fully open during the current shift is calculated as tf = Vr ・α/Q1
... (1) α: Calculate and set as the oil filling volume ratio when the valve is fully open. Also, prior to measuring the piston cylinder volume, the measurement register VLRn is cleared and initialized.

In step S12, the solenoid valve 4
The duty ratio DLR of 3 is set to D1 (valve fully open), and the output is output, and filling of oil into the cylinder is started.

In step S13, the timer is cleared and started in order to set the oil filling time to the set value tf.

In step S14, the initial setting is completed, and the shift process is set to phase=1 as shown in FIG. 6(h), and the process proceeds to step S15 and step S16.

In step S15, the current valve drive n
Solenoid valve output duty ratio DLR during cycle
The oil flow rate QLRn flowing from n into the piston cylinder of the low reverse brake B1 is expressed as: QLRn = QO ・DLRn ・K1
...Calculated as (2).

[0048] Here, QO is the reference value of the discharge flow rate when the valve is fully open under the specified line pressure and oil temperature, and K1 is the correction coefficient for the line pressure and oil temperature. For example, the oil temperature is detected as a function of the engine rotational speed NE and the oil temperature is detected by an oil temperature sensor (not shown), and a correction coefficient is determined.

In step S16, the piston cylinder volume VLRn during n cycles of valve driving is determined as VLRn=
VLRn-1 +QLRn...
(3) and is measured every valve drive cycle.

Here, VLRn-1 is the cylinder volume determined from the integrated value of the flow rate that has flowed into the piston cylinder up to the previous drive cycle (n-1).

Next, when the shift process moves to phase 1, the process proceeds from step S10 to step S17, and step S1
7, the turbine rotational acceleration (dNt/dt) obtained from the difference value between the latest turbine rotational speed Ntn obtained in step S3 and the previous sampling value Ntn-1 is in a negative state, and the turbine rotational acceleration (dNt/dt) obtained in step S4 is negative. As shown in FIG. 6(f), the start of engagement of the low reverse brake B1 is determined based on whether or not the speed ratio E of the torque converter 2 has become equal to or less than a predetermined value Er.

If it is determined that this combination has started, the process proceeds from step S17 to step S20; if not, the process branches from the N side of step S17 and proceeds to step S18.

In step S18, the timer value t is low.
Set value tf of oil filling time for reverse brake B1 (
It is determined whether the state shown in FIG. 6(a)) has been reached, and if t<tf, the valve is kept fully open and the piston cylinder is filled with oil at the maximum flow rate. After processing, the process returns to the main routine, and if t>tf, the process advances from step S18 to step S19.

In this step S19, in preparation for the start of engagement of the low reverse brake B1, the discharge flow rate of the valve is throttled, and oil is gradually filled into the piston cylinder (flow rate = Q2 shown in FIG. 6(b)). In order to stroke the piston at a low speed, the duty ratio DLR (FIG. 6(a)) of the solenoid valve 43 is set to a predetermined value D2 and output, and then the process proceeds to step S15 and step S16, and the same process as described above is performed. and return to the main routine.

On the other hand, when the start of engagement of the low reverse brake B1 is detected, steps S17 to S20 are performed.
In step S20, the shift process is changed to phase=
2 to set the shift process transition, and step S21
Proceed to.

[0056] In this step S21, the step S21
The piston cylinder volume VLRn obtained in step 16 (Fig. 6
(c) ) obtained by this shift operation.
The learned value Vr of the piston cylinder volume from the start of oil filling into the piston cylinder of the reverse brake B1 to the start of coupling is stored in the memory.

In step S22, the connection of the low reverse brake B1 is determined based on the turbine rotational speed Nt (FIG. 6(e)
)) The duty ratio DLR of the solenoid valve 43 is set to a duty value D3 calculated by, for example, a well-known P-I control formula so that the turbine rotational acceleration calculated from the difference value of (Figure 6(a))
It is output as a hydraulic control signal 56 to perform feedback control.

When the shift process shown in FIG. 6(h) moves to the coupling area of the low reverse brake B1 of phase=2, the process proceeds from step S10 to step S23, and in step S23, the completion of coupling of the low reverse brake B1 is determined. For example, the determination is made based on whether the turbine rotational speed Nt obtained in step S3 has become less than or equal to a predetermined value,
If it is equal to or greater than the predetermined value, the above-described feedback control is performed in step S22.

When the turbine rotational speed Nt becomes less than the predetermined value, the process proceeds to step S24, where the duty ratio of the solenoid valve 43 is outputted as DLR=D1 (fully open), the low reverse brake B1 is kept in the engaged state, and the process proceeds to step S24. In S25, the phase is cleared and the N-D shift control is ended.

The above-mentioned FIG. 6 shows a time chart of the above-mentioned N-D shift process, and further explanation will be added here. FIG. 6(a) shows the duty ratio D of the solenoid valve 43.
LR, FIG. 6(b) shows the oil flow rate QLR flowing into the piston cylinder of the low reverse brake B1 calculated based on the output duty ratio DLR of the solenoid valve 43,
Fig. 6(c) shows the piston cylinder volume VLR of the low reverse brake B1 obtained by integrating the oil flow rate QLR in Fig. 6(b), and Fig. 6(d) shows the oil pressure PLR supplied to the low reverse brake B1. 6(e) is the engine rotation speed NE
and turbine rotational speed NT, FIG. 6(f) shows the speed ratio E of the torque converter, FIG. 6(g) shows the shaft torque TO, and FIG. 6(h) shows the shift control phase.

[0061]

As described above, according to the invention of claim 1, the connection start point of the hydraulic friction element is detected from the speed ratio of the torque converter during the shift operation accompanying the start of the vehicle, and the connection start point of the hydraulic friction element is detected before the start of connection. The oil flow rate control in the invalid stroke operation region of the hydraulic piston and the hydraulic control in the torque coupling region after the start of coupling are controlled with high precision to directly achieve the first speed, so the drive shaft torque change can be controlled smoothly, the shift shock is small, and the N
- When shifting to D, the 1st gear position is directly obtained, which has the effect of improving the responsiveness of starting.

Further, according to the second aspect of the invention, the coupling start point of the hydraulic friction element is detected from the speed ratio of the torque converter and the acceleration state of the output shaft of the torque converter during a shift operation accompanying the start of the vehicle. , oil flow rate control in the invalid stroke operation region of the hydraulic piston before the start of coupling;
Since the hydraulic control in the torque coupling region after the start of coupling is controlled with high precision to directly achieve the first gear, it is possible to control the drive torque change smoothly, and the shift shock is small. , during N-D shifting, the 1st gear position is directly obtained, which has the effect of improving the responsiveness of starting.

According to the third aspect of the invention, the discharge flow rate of the solenoid valve during the hydraulic piston stroke associated with the coupling operation of the hydraulic friction elements is calculated from the drive signal of the solenoid valve, and Since the flow rate is determined by correcting the flow rate, it is possible to shorten the time required to start the coupling operation of the hydraulic friction elements.

According to the fourth aspect of the invention, the volume of the hydraulic piston cylinder necessary for stroke and coupling operation of the hydraulic piston of the hydraulic friction element is controlled from the start of filling oil into the piston cylinder of the hydraulic friction element. Since the piston cylinder volume is calculated from the integrated value of the flow rate discharged by the solenoid valve until the start of connection is detected, and the piston cylinder volume is learned, the time for connecting the hydraulic friction elements can be substantially shortened. It has the effect of

According to the fifth aspect of the invention, when starting to fill oil into the hydraulic piston cylinder during the next shift, the discharge time with the solenoid valve fully open is set based on the learned value of the hydraulic piston cylinder volume. By filling with oil, there is an effect that a quick and smooth coupling operation of the hydraulic friction elements can be obtained, even against operating conditions during shifting, aging of parts, individual differences, etc.

According to the sixth aspect of the invention, after the detection of the start of coupling of the hydraulic friction elements, feedback control is performed by the solenoid valve control means so that the rotational acceleration of the torque converter output shaft matches a predetermined target value. This configuration has the effect of being able to control changes in drive shaft torque smoothly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of main parts of a control device for an automatic transmission according to an embodiment of the present invention.

2 is a schematic diagram of an auxiliary transmission with three forward speeds using a double pinion planetary gear set applied to the embodiment of FIG. 1; FIG.

FIG. 3 is a block diagram of a hydraulic control circuit for an automatic transmission applied to the embodiment of FIG. 1;

FIG. 4 is a flowchart showing the main flow of the embodiment of FIG. 1;

FIG. 5 is a flowchart showing an ND shift execution flow in the embodiment of FIG. 1;

FIG. 6 is a time chart when performing an ND shift in the embodiment of FIG. 1;

[Explanation of symbols]

1 Engine 2 Torque converter 3 Auxiliary transmission 4 Hydraulic control section 5 Control unit 40 Oil pump 41 Pressure regulator valve 42 Shift control valve 43 Solenoid valve 44 Solenoid valve 45 Solenoid valve B1 Low reverse brake B2 Second brake C1 Front clutch C2 Rear clutch

Claims (6)

[Claims] 1. A torque converter that rotates internal hydraulic oil using an input element driven by an engine and rotates an output element while increasing torque by reaction force from a stator;
An auxiliary transmission that is connected to the output element of this torque converter to transmit power to the tires and provide a gear ratio according to the vehicle's driving condition, and a hydraulic pressure that controls the oil pressure supplied to the hydraulic friction element within this auxiliary transmission. When the control device and the shift switching means operated by the driver control the coupling operation of the hydraulic friction element according to the range selected from the neutral range to the drive range, the input shaft rotational speed and output of the torque converter are controlled. The speed ratio with the shaft rotational speed is calculated, and the connection start point of the hydraulic friction element is detected based on this speed ratio, and the oil flow rate into the hydraulic piston cylinder and the hydraulic pressure are controlled during the preparation period for the connection of the hydraulic friction element. A control device for an automatic transmission equipped with a control unit that performs control. 2. The control unit controls the torque converter when the shift switching means operated by the driver controls the coupling operation of the hydraulic friction element according to the range selected from the neutral range to the drive range. The speed ratio and difference between the input shaft rotational speed and the output shaft rotational speed are determined, and the acceleration is calculated from this difference, and when the speed ratio is below a predetermined value and the acceleration is negative, the hydraulic friction element is coupled. 2. The automatic transmission control device according to claim 1, wherein the automatic transmission control device detects the start and performs oil flow control and oil pressure control into the hydraulic piston cylinder during a preparation period for coupling the hydraulic friction element. 3. The control unit calculates the discharge flow rate of the electrohydraulic conversion valve during the hydraulic piston stroke associated with the coupling operation of the hydraulic friction element from the drive signal of the electrohydraulic conversion valve, and calculates the discharge flow rate of the electrohydraulic conversion valve from the drive signal of the electrohydraulic conversion valve, and 2. The control device for an automatic transmission according to claim 1, wherein the flow rate is corrected for temperature changes. 4. The control unit controls the hydraulic piston cylinder volume necessary for stroke and coupling operation of the hydraulic piston of the hydraulic friction element from the start of filling oil into the hydraulic piston cylinder of the hydraulic friction element. Claim 1 characterized in that the piston cylinder volume is learned by calculating from the integrated value of the flow rate discharged by the electrohydraulic conversion valve until the start of coupling of the hydraulic friction element is detected.
A control device for the automatic transmission described above. 5. The control unit is configured to perform hydraulic control from the start of filling oil into the hydraulic piston cylinder of the hydraulic friction element at the time of starting filling oil into the hydraulic piston cylinder when the hydraulic friction element is coupled. The discharge time at the maximum flow rate of the electro-hydraulic conversion valve is set based on the learned value of the hydraulic piston cylinder volume, which is calculated from the integrated value of the flow rate discharged by the electro-hydraulic conversion valve until the start of coupling of the friction elements is detected. 2. The control device for an automatic transmission according to claim 1, wherein control is performed to start filling the hydraulic piston cylinder with oil. 6. The control unit feeds back a hydraulic control signal to the hydraulic control device so that the rotational acceleration of the torque converter output shaft matches a predetermined target value after detection of the start of coupling of the hydraulic friction element. The automatic transmission control device according to claim 1, characterized in that: