JPH0735230A - Line pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To improve transmission performance at the time of throttle returning speed change by limiting a line pressure during the speed change controlled by a line pressure control means to be the lowest limit value or more when change of a throttle opening to be a specified opening or less is detected during the speed change. CONSTITUTION:A device is provided with a throttle sensor, a vehicle sensor 18, and a turbine sensor 19 to take a rotation signal from an input shaft of a gear type transmission 4, and their output signals are inputted to a control unit 13. Various solenoid valves are controlled to achieve a specified gear shift position based on information of a car speed, a throttle valve opening, a select lever position, etc., and a solenoid valve 10 is duty-controlled to control a line pressure at the time of speed change. The line pressure during the speed change is set in accordance with an input side rotation speed at the time of completion of the speed change, and in this case, when change of the throttle opening to be a specified opening or less is detected, the line pressure during the speed change is limited to be a specified lowest limit value or more, thereby speed change responsiveness is secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line pressure control device for an automatic transmission, and more specifically, it predicts a rotational speed of an input side at the end of a shift and calculates the input torque of the transmission based on the prediction result. Accordingly, the present invention relates to a device for controlling the line pressure during shifting.

[0002]

2. Description of the Related Art In an automatic transmission mounted on a vehicle, it is desirable to adjust the line pressure according to the input torque to the transmission. Therefore, JP-A-3-24946
In the line pressure control device disclosed in Japanese Patent Publication No. 8, the output torque of the engine is obtained in accordance with the intake air amount, while at the time of gear shift, the amount of energy (hereinafter referred to as inertia torque) generated by the change in rotation speed accompanying gear shift is described above. The input torque to the transmission is calculated in addition to the output torque of the engine, and the line pressure control according to the input torque is performed.

In the calculation process of the inertia torque, first, at the end of the gear shift, based on the input side rotation speed (engine rotation speed or turbine rotation speed of the torque converter) at the start of the gear shift and the gear ratio before and after the gear shift. The input side rotational speed is predicted, and then the inertia torque is calculated from the change in the rotational speed obtained based on the prediction result and the shift time.

[0004]

By the way, in the calculation of the inertia torque as described above, when gear shifting is performed with the throttle opening substantially constant, gear shifting is performed by assuming that the vehicle speed during gear shifting is constant. The rotation speed on the input side at the end can be obtained according to the gear ratio, but when a shift (shift up) is performed in accordance with a throttle return operation (hereinafter, simply referred to as throttle return shift), a shift is performed. The prediction result of the input side rotation speed at the time of termination was very different from the actual value, and the inertia torque could not be obtained accurately, and the line pressure to be set was different from the request and the gear shifting performance was sometimes deteriorated.

That is, for example, at the time of throttle full-close return shift-up gear shift, and under the condition that the engine brake is not operated, the input side rotation speed at the end of gear shift is reduced to idle rotation, but the rotation speed at the start of gear shift is In the control that predicts the input side rotation speed at the end of the shift from the gear ratio and the gear ratio, a rotation speed higher than the idle rotation is predicted, so a torque lower than the inertia torque actually generated is set, and Therefore, a line pressure lower than required will be set. Then, by controlling the line pressure to be lower than the request, there arises a problem that the response of the gear shifting operation is deteriorated.

The present invention has been made in view of the above problems, and even when throttle return gear shifting is performed,
It is an object of the present invention to be able to accurately calculate the inertia torque, and thus to appropriately control the line pressure during shifting.

[0007]

Therefore, a line pressure control device for an automatic transmission according to the present invention is provided with a line pressure supplied to a hydraulic circuit for controlling each shift element of the automatic transmission that constitutes a power transmission system of an engine. Is a line pressure control device for an automatic transmission, which is configured as shown in FIG. 1 or 2.

In FIG. 1, the rotation speed detecting means detects the rotation speed on the input side of the transmission, and the line pressure setting means is
The input side rotation speed at the end of the gear shift is calculated based on the input side rotation speed detected by the rotation speed detection means at the start of the gear shift and the gear ratio of the transmission before and after the gear shift, and the gear shift based on the calculation result. Set the inside line pressure. Then, the line pressure control means controls the line pressure supplied to the hydraulic circuit according to the set line pressure.

On the other hand, the throttle opening detecting means detects the throttle opening of the engine, and the line pressure limiting means detects that the throttle opening has been changed to a predetermined opening or less by the throttle opening detecting means during shifting. When detected,
The line pressure during the shift controlled by the line pressure control means is limited to a predetermined lower limit value or more. In FIG. 2, the rotation speed detecting means detects the input side rotation speed of the transmission, and the line pressure setting means detects the input side rotation speed detected by the rotation speed detecting means at the start of the shift and before and after the shift. The rotational speed of the input side at the end of the shift is calculated based on the gear ratio of the transmission and the line pressure during the shift is set based on the calculation result.

On the other hand, the throttle opening detection means detects the throttle opening of the engine, and the throttle change time line pressure setting means changes the throttle opening to a predetermined opening or less by the throttle opening detection means during shifting. When it is detected, the rotational speed of the input side at the end of the shift is updated and set, and instead of the line pressure setting means, the line pressure during the shift is changed based on the updated rotational speed of the input side. To set.

The line pressure control means controls the line pressure supplied to the hydraulic circuit according to the set line pressure. Here, when the transmission includes a friction element that applies an engine brake by being engaged during deceleration, the rotation of the input side at the end of the shift that is updated and set by the throttle change time line pressure setting means. It is preferable to provide speed change setting means at the end of gear shift for changing the speed according to the operating state of the friction element.

[0012]

According to this structure, the input side rotational speed at the end of the shift is predicted and calculated based on the input side rotational speed and the gear ratio at the start of the shift, and the predicted rotational speed at the end of the shift is calculated. Knowing the change in rotation speed (the amount of energy generated by rotation change) associated with gear shifting,
The line pressure during shifting is set accordingly.

Here, when it is detected that the throttle opening becomes equal to or less than a predetermined opening during gear shifting, that is, when the throttle return gear shifting is performed, the rotational speed of the input side at the end of the actual gear shifting is Since the line pressure that is lower than the predicted value and set based on the predicted and calculated rotation speed may be lower than the required level, a limit is added so that the line pressure that is at least lower than the predetermined lower limit value is not set. The line pressure is not controlled to be much lower than the required level even during throttle return gear shifting.

Further, when the throttle opening degree changes to a predetermined opening degree or less during gear shifting, the accuracy of the input side rotational speed at the end of gear shifting estimated based on the input side rotational speed at the start of gear shifting is If the change in the throttle opening is detected during the shift, the rotational speed at the end of the shift is updated and set, and the line pressure is newly set according to the updated set rotational speed.

Here, in the case where a friction element for operating the engine brake is provided, the rotational speed at the end of the gear shift differs depending on the operating state of the friction element even if the throttle opening changes the same. Therefore, the rotational speed at the end of the shift to be updated and set is changed depending on the operating state of the friction element.

[0016]

EXAMPLES Examples of the present invention will be described below. In FIG. 3, which schematically shows the system configuration of one embodiment, an automatic transmission 2 is provided on the output side of an engine 1 mounted on a vehicle (not shown). The automatic transmission 2 includes a fluid type torque converter 3 interposed on the output side of the engine 1, a gear type transmission 4 connected via the fluid type torque converter 3, and various types of gears in the gear type transmission 4. And a hydraulic actuator 5 for connecting / disengaging the speed change element. The operating oil pressure for the hydraulic actuator 5 is controlled via various electromagnetic valves, but only the electromagnetic valves 6A and 6B for shifting for automatic shifting are shown here. Reference numeral 7 is an output shaft of the automatic transmission 2.

Here, in order to obtain a line pressure, which is an operating oil pressure for the hydraulic torque converter 3 and the hydraulic actuator 5, an oil pump 8 driven by an input shaft of the gear type transmission 4 is used, and a pilot valve 9 is used. ， Electromagnetic valve 10 ， Pressure modifier valve 11
And a pressure regulator valve 12 are provided.

The pilot valve 9 regulates the discharge pressure of the oil pump 8 to the pilot pressure acting on the electromagnetic valve 10. The electromagnetic valve 10 is a control unit as described later.
The duty is controlled by 13, and the pilot pressure is adjusted to the throttle pressure according to the operating condition.The pressure modifier valve 11 adjusts the pilot pressure to the pressure modifier pressure according to the throttle pressure and acts on the pressure regulator valve 12. To do. The pressure regulator valve 12 regulates the oil pump discharge pressure to a line pressure proportional to the pressure modifier pressure, and sends it to a hydraulic circuit such as the hydraulic torque converter 3 and the hydraulic actuator 5.

Signals from various sensors are input to the control unit 13. The various sensors include the opening degree TVO of the throttle valve 14 of the intake system of the engine 1.
Potentiometer-type throttle sensor 15 for detecting
(Throttle opening detection means) is provided. Also,
A crank angle sensor 16 is provided on a crank shaft of the engine 1 or a shaft (cam shaft) that rotates in synchronization with the crank shaft. The signal from the crank angle sensor 16 is, for example, a pulse signal for each reference crank angle, and the engine rotation speed Ne is calculated by the generation period thereof.

Further, an air flow meter 17 for detecting the intake air flow rate Q is provided in the intake system of the engine 1. Further, the output shaft 7 of the automatic transmission 2 is provided with a vehicle speed sensor 18 for detecting the vehicle speed VSP, and a rotation signal (turbine rotation speed) from the turbine liner of the torque converter 3 or the input shaft of the gear type transmission 4 is provided. ) A turbine sensor 19 (rotational speed detecting means) for extracting Nt is provided.

The control unit 13 controls the vehicle speed VS.
P and throttle valve opening TVO, and further, based on information such as the position of the select lever operated by the driver, various solenoid valves are controlled so as to reach a predetermined shift position, and are supplied to a hydraulic circuit as described later. Line pressure PL
It has a function to control. Here, the state of the line pressure PL control at the time of shifting performed by the control unit 13 performing duty control of the electromagnetic valve 10 will be described with reference to the flowchart of FIG. In the present embodiment, the functions of the line pressure setting means, the line pressure control means, and the line pressure limiting means are provided in software by the control unit 13 as shown in the flow chart of FIG.

In the flowchart of FIG. 4, first, in step 1 (denoted as S1 in the figure, the same applies hereinafter),
The input torque TQSEN for the gear type transmission 4 is calculated. The input torque TQSEN is obtained as the sum of the output torque TQENG of the engine 1 and the energy component (inert torque) TQINS generated by the change in rotation speed associated with the gear shifting operation (TQSEN ← TQENG + T
QINS).

Output torque TQENG of the engine 1
Is the intake air flow rate Q detected by the air flow meter 17 and the engine speed Ne detected by the crank angle sensor 16.
Is calculated as a value proportional to the cylinder intake air amount (TQENG ← k × Q / Ne: k is a constant). On the other hand, the inertia torque TQINS has an equivalent inertia moment of the turbine It, a gear ratio before the shift is G ₁ , a gear ratio after the shift is G ₂ , a target shift time is T, and the turbine sensor 19 detects the shift at the start of the shift. When the turbine rotation speed (rotation speed on the input side) is Nts,

[0024]

[Equation 1]

Assuming that the turbine rotation speed at the end of the shift is Nt _E and the vehicle speed VSP is constant, Nt _E =
Since Nts × G ₂ / G ₁ , the above equation ₁ can be rewritten as the following equation 2.

[0026]

[Equation 2]

That is, the inertia torque TQINS calculated by the above equation 1 determines the turbine rotation speed Nt _E at the end of the gear shift based on the turbine rotation speed Nts at the start of the gear shift and the gear ratios G ₁ and G ₂ before and after the gear shift. It is obtained as a value proportional to the change of the turbine rotation speed Nt obtained by the prediction. In step 2, the line pressure PL is set based on the input torque TQSEN obtained as described above.

In step 3, it is determined whether or not gear shifting is in progress. When the gear change is not in progress, the line pressure control based on the line pressure PL for steady time, which is separately set, is performed, but in the flowchart of FIG. 4, steps corresponding to such processing are omitted. On the other hand, if it is determined that the gear is being changed, the control based on the line pressure PL set in step 2 is performed, and the process proceeds to step 4 to determine whether the engine 1 is in the idle operation state. Determine. The throttle sensor is used to determine the idle operation state.
The opening degree TVO of the throttle valve 14 detected at 15 is performed depending on whether or not it is at the idle position.

When it is determined in step 4 that the engine is not in the idle operation state, the line pressure P set in step 2 is set.
To control according to L, this program is terminated as it is. On the other hand, when it is determined that the engine is in the idle operation state, the routine proceeds to step 5, where the lower limit value of the line pressure is set according to the type of gear shift and the like.

Then, in the next step 6, it is judged whether or not the line pressure PL set in the step 2 is lower than the lower limit value set in the step 5. If the line pressure PL set in step 2 is below the lower limit value, the process proceeds to step 7 and the line pressure PL
The lower limit value is set as, and the line pressure PL is restricted so as not to fall below the lower limit value.

The control unit 13 controls the electromagnetic valve 10 with a duty corresponding to the set line pressure PL to adjust the line pressure PL. If an idle operation state is detected during a gear shift, it can be considered that the throttle is being returned to a shift (when the throttle is fully closed and the gear is up), and the engine brake is activated during that gear shift. when non like, the input rotational speed at the shift end (turbine speed Nt) decreases to an idle rotational speed Nt _I.

However, the prediction of the turbine rotational speed Nt _E at the end of the shift based on the turbine rotational speed Nts at the start of the shift and the gear ratios G ₁ and G ₂ before and after the shift is performed with the throttle valve opening TVO kept constant. Is performed (see FIG. 7), and when the throttle return shift is performed as described above (see FIG. 8), the turbine rotation speed Nt _E at the end of the shift is predicted to be higher than the actual speed. Rotational changes (inert torque TQINS) will be underestimated. Therefore, if the line pressure PL set in step 2 is used as it is during the throttle return shift, the line pressure PL is controlled to be lower than the required level.
The gear shift response will deteriorate.

Therefore, when the idle operation state is detected during the shift, it is considered that the throttle return shift is being performed, and the line pressure PL at least below the lower limit value is not set. The minimum line pressure PL is limited to the lower limit value. As a result, even during the throttle return gear shift, the line pressure PL is not controlled to be much lower than the required level, and it is possible to prevent the gear shift response from being significantly deteriorated.

In step 4 of the above embodiment, it is determined whether the throttle valve 14 is fully closed (idle position). However, the opening TVO is determined according to the vehicle speed VSP. You may make it discriminate | determine whether it is below the value (TVORL shown in FIG. 9) corresponding to load: R / L). By the way, in the above embodiment, when the throttle return shift is performed, the input torque TQS is
Since the accuracy of the line pressure PL set according to EN is deteriorated, the line pressure PL is controlled so as not to fall below a predetermined lower limit value, and is controlled to a line pressure PL that is significantly below the required level. However, the turbine rotation speed Nt _E at the end of the shift may be updated and set to a value corresponding to the throttle return shift, and the line pressure PL corresponding to the throttle return shift may be newly calculated. A second embodiment for performing such processing will be described below with reference to the flowchart of FIG.

In the second embodiment, the functions of the line pressure setting means, the line pressure control means, and the line pressure setting means during throttle change are provided by the control unit 13 as software, as shown in the flowchart of FIG. ing. In the flowchart of FIG. 5 showing the control contents of the second embodiment, first, at step 11, the engine output torque TQENG is calculated.

Then, in the next step 12, it is determined whether or not the shift is in progress, and the line pressure PL is controlled in accordance with the difference between the turbine rotation speed Nt at the start and end of the shift. To proceed to step 13. In step 13,
Throttle valve opening TV detected by the throttle sensor 15
O is a predetermined opening (Fig. 9) corresponding to the flat road running resistance (load / load: R / L) determined according to the vehicle speed VSP.
(TVORL) shown in (4) or less is determined.

Here, when a change in the opening TVO below the predetermined opening is detected, the turbine rotation speed N at the end of the shift, during the throttle return shift-up shift.
It is determined that t _E is the idling speed, and the routine proceeds to step 14. Note that the step 13 may be configured to detect idle. In step 14, the turbine rotation speed N detected by the turbine sensor 19 at the start of gear shifting
ts and the turbine rotation speed Nt in the idle operation state
_The inertia torque TQINS is calculated according to the equation (3) based on _I and.

[0038]

[Equation 3]

On the other hand, if there is no change in the opening TVO below the predetermined opening, the routine proceeds to step 15, where the inertia torque TQINS is calculated in accordance with the equation (1). That is, when the opening TVO changes to a predetermined opening or less corresponding to the flat road running resistance, assuming that the engine brake does not operate, the turbine rotation speed Nt _E at the end of the shift is determined.
Is not a value predicted based on the turbine rotation speed Nts and the gear ratio at the start of gear shift, but is predicted to be a lower idle rotation speed Nt _I. Therefore, the value predicted based on the turbine rotation speed Nts and the gear ratio at the start of gear shifting is
The idle rotation speed Nt _I is updated and set, and the inertia torque TQINS is newly calculated in accordance with the updated setting.

Therefore, the inertia torque TQINS can be calculated to a value commensurate with the actual change in the rotational speed at the time of the throttle return shift, and thus the input torque TQSEN.
Can be set with high precision and the line pressure can be adjusted to meet the demand during the shift, and the shift responsiveness can be ensured. As described above, when the inertia torque TQINS is calculated according to the determination as to whether or not the throttle return shift is performed, in step 16, the engine output torque TQENG calculated in step 11 and the inertia torque TQINS are calculated. Then, the result of the addition is used as the input torque TQSEN for the transmission.

Then, in the next step 17, the line pressure PL is set on the basis of the input torque TQSEN, and the electromagnetic valve 10 is controlled with a duty corresponding to the line pressure PL to set the set line pressure PL. adjust. By the way, in the above-described embodiment, at the time of the throttle return shift-up shift, the turbine rotation speed (rotation speed on the input side) Nt at the end of the shift becomes the idle rotation speed Nt _I when the engine brake is not operated. Calculated inertia torque TQINS.

However, in the case of a transmission having a friction element (hereinafter referred to as an overrun clutch) for selectively activating the engine brake, the engagement is controlled through engagement control of the overrun clutch (not shown). Depending on the engine brake control, the turbine rotation speed Nt _E at the end of the shift at the time of the throttle return shift is different,
Rotational speed changes depending on the engine brake control status,
Consequently, the required line pressure PL during shifting is different.

Therefore, the third embodiment in which the setting characteristic of the line pressure PL (setting of the turbine rotational speed Nt _E at the end of the shift) at the time of the throttle return shift is made different according to the state of the engine brake control will be described. Follow the instructions below. In the third embodiment, the functions of the control unit 13 as the line pressure setting means, the line pressure control means, the throttle changing line pressure setting means, and the speed change ending speed switching setting means are shown in the flow chart of FIG. .

In the flowchart of FIG. 6, first, in step 21, the engine output torque TQENG is calculated,
If the throttle opening TVO is not changing below the predetermined opening corresponding to the flat road running resistance during shifting (steps 22 and 23), the turbine rotation speed Nts and the gear ratio at the start of shifting are changed. Based on the above, the turbine speed Nt _E at the end of the shift is predicted to calculate the inertia torque TQINS (see equation 1) (step 24).

On the other hand, when the throttle opening TVO changes to the predetermined opening or less during the gear shift, it is considered that the throttle return gear is being shifted, and the routine proceeds to step 25, where the overrun clutch is engaged (engine braking). It is determined whether or not it is the operating state of. When the overrun clutch is in the non-engaged state (OFF) and the engine brake does not operate, the routine proceeds to step 26, where the idle rotation speed Nt _I is set to the turbine rotation speed Nt _E at the end of the shift.

On the other hand, when the engine brake is actuated when the overrun clutch is engaged (ON), the routine proceeds to step 27, where the turbine speed Nt _E at the end of the shift is the vehicle speed VSP, the gear ratio Gr after the shift, and the constant k. The rotation speed calculated based on and is set (Nt _E ← k ×
VSP x Gr). That is, when the engine brake is not applied, the reverse driving force from the drive wheels is not transmitted to the engine 1 side, and therefore the rotation is reduced to the idle rotation speed Nt _I during the throttle return shift-up gear shifting. When the vehicle speed VSP is constant, the turbine rotation speed Nt _E at the end of the gear shift can be obtained by the vehicle speed VSP, the gear ratio after the gear shift, and the slip of the torque converter 3. Yes, the constant k is a correction coefficient for dealing with the slip.

As described above, the turbine rotation speed Nt at the end of the shift is determined according to the operating state of the overrun clutch.
_{When E} is updated and set with each characteristic, in step 28, the inertia torque TQINS is calculated in accordance with the above equation 2 based on the set turbine rotation speed Nt _E at the end of gear shift. Then, in step 29, the input torque TQSEN is obtained based on the inertia torque TQINS and the engine output torque TQENG, and in the next step 29,
The input torque TQSEN is converted into the line pressure PL.

As described above, if the turbine rotation speed Nt _E at the end of the shift is updated and set depending on whether the overrun clutch is operating during the throttle return shift, regardless of the operating state of the engine brake. In addition, the inertia torque TQINS generated by the rotation change due to the gear shift can be set with high accuracy, and thus the line pressure PL during the gear shift can be controlled to the required level.

In each of the above embodiments, the turbine rotation speed Nt detected by the turbine sensor 19 is used as the rotation speed on the input side of the transmission. However, in a system without the turbine sensor 19, the turbine rotation speed Nt. Instead of, the engine rotation speed Ne detected by the crank angle sensor 16 may be used.

[0050]

As described above, according to the present invention, in the structure in which the rotational speed of the input side at the end of the gear shift is predicted and the line pressure during the gear shift is controlled according to the energy generated by the rotation fluctuation accompanying the gear shift, The accuracy of the predictive control based on the input side rotation speed and gear ratio at the start of gear shift deteriorates.Through throttle return gear shift, it is possible to avoid the line pressure being controlled far below the required level and the gear shift responsiveness deteriorated. As a result, there is an effect that the gear shifting property at the time of throttle return gear shifting can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention.

FIG. 2 is a block diagram showing the basic configuration of the present invention.

FIG. 3 is a system schematic diagram showing an embodiment of the present invention.

FIG. 4 is a flowchart showing line pressure control in the first embodiment.

FIG. 5 is a flowchart showing line pressure control in the second embodiment.

FIG. 6 is a flowchart showing line pressure control in the third embodiment.

FIG. 7 is a time chart showing characteristics at the time of gear shifting with a constant throttle opening.

FIG. 8 is a time chart showing characteristics during throttle return gear shifting.

FIG. 9 is a diagram showing a determination value of a throttle opening in the embodiment.

[Explanation of symbols]

 1 Engine 2 Automatic Transmission 3 Fluid Torque Converter 4 Gear Transmission 5 Hydraulic Actuator 7 Output Shaft 8 Oil Pump 9 Pilot Valve 10 Electromagnetic Valve 11 Pressure Modifier Valve 12 Pressure Regulator Valve 13 Control Unit 14 Throttle Valve 15 Throttle Sensor 16 Crank angle sensor 17 Air flow meter 18 Vehicle speed sensor 19 Turbine sensor

Claims (3)

[Claims] 1. A line pressure control device for an automatic transmission that controls a line pressure supplied to a hydraulic circuit that controls each shift element of an automatic transmission that constitutes a power transmission system of an engine, the input of the transmission. Rotation speed detecting means for detecting the rotation speed of the input side, and a rotation speed detecting means for detecting the rotation speed of the input side at the end of the shift based on the rotation speed of the input side detected by the rotation speed detecting means at the start of the shift and the gear ratio of the transmission before and after the shift. Line pressure setting means for calculating the rotational speed and setting the line pressure during shifting based on the calculation result, and line pressure control for controlling the line pressure supplied to the hydraulic circuit according to the set line pressure. Means, throttle opening detecting means for detecting the throttle opening of the engine, and when the throttle opening detecting means detects that the throttle opening has changed to a predetermined opening or less during gear shifting. , The line pressure control device for an automatic transmission, characterized in that it is configured to include a, a line pressure limitation means for limiting the line pressure during shifting than a predetermined lower limit value to be controlled by the line pressure control means. 2. A line pressure control device for an automatic transmission, which controls a line pressure supplied to a hydraulic circuit for controlling each shift element of an automatic transmission that constitutes a power transmission system of an engine, wherein an input of the transmission is provided. Rotation speed detecting means for detecting the rotation speed of the input side, and a rotation speed detecting means for detecting the rotation speed of the input side at the end of the shift based on the rotation speed of the input side detected by the rotation speed detecting means at the start of the shift and the gear ratio of the transmission before and after the shift. Line pressure setting means for calculating the rotational speed and setting the line pressure during shifting based on the calculation result, throttle opening detecting means for detecting the throttle opening of the engine, and the throttle opening detecting means during shifting When it is detected that the throttle opening has changed to a predetermined opening or less, the rotational speed of the input side at the end of the shift is updated and set, and the line pressure setting means is replaced by the update setting. A throttle changing line pressure setting means for setting a line pressure during shifting based on a fixed input side rotation speed, and a line for controlling the line pressure supplied to the hydraulic circuit according to the set line pressure. A line pressure control device for an automatic transmission, comprising: a pressure control means. 3. The input transmission is rotated at the end of gear shift, which is updated and set by the throttle change time line pressure setting means, while the transmission is provided with a friction element for operating an engine brake by being engaged during deceleration. 3. The line pressure control device for an automatic transmission according to claim 2, further comprising speed change setting means at the end of gear change for changing the speed according to the operating state of the friction element.