JPH0631246Y2 - Hydraulic control of automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic control device for an automatic transmission, which controls the operation of an automatic transmission provided in a vehicle or the like using hydraulic pressure.

(Prior Art) As an automatic transmission provided in a vehicle, an automatic transmission configured by combining a torque converter and a multi-gear type speed change mechanism is widely used. Such an automatic transmission is usually equipped with a hydraulic control device having a hydraulic circuit section as a main component.

In a hydraulic circuit unit of a hydraulic control device, a line pressure forming unit usually composed of a regulator valve or the like for adjusting a hydraulic pressure from an oil pump to form a line pressure, and a manually operated valve which is manually operated to switch a shift range, A plurality of shift valves that form an operating oil pressure based on the line pressure from the line pressure forming unit, and selectively supply the operating oil pressure to a plurality of hydraulically controlled friction engagement elements such as clutches and brakes in a speed change mechanism, And a working hydraulic pressure supply unit including a plurality of solenoid valves for switching the operating state of the shift valve. In the shift control of the automatic transmission, the control unit provided in the hydraulic control device compares the shift line in the shift pattern diagram stored in the built-in memory with the load of the engine and the vehicle speed. It is determined whether or not the shift condition is satisfied, and when it is determined that the shift condition is satisfied,
A drive signal is supplied from the control unit to a predetermined solenoid valve provided in the hydraulic pressure supply section to switch the operation state of the shift valve, whereby a selected one of the plurality of friction engagement elements is engaged, Alternatively, the gears are released and the shift range and shift stage of the automatic transmission are switched.

In such a hydraulic control device, in order to perform finer control, a solenoid valve is provided in the line pressure forming unit, and the line pressure is controlled by controlling the opening period of this solenoid valve. The one which is designed to be changed according to the opening degree of the throttle valve arranged in the intake passage is known as disclosed in, for example, Japanese Patent Publication No. 54-2349. Further, in the hydraulic control device that is configured to change the line pressure, when the shift range and the shift stage of the automatic transmission are changed, the line pressure is changed in order to suppress the shift shock accompanying the change. It is also conceivable to change the range and the gear according to the switching mode.

(Problems to be solved by the invention) However, as described above, in the hydraulic control device that is configured to perform control to change the line pressure, the hydraulic oil that causes the line pressure has a higher viscosity as the temperature decreases. Therefore, when the temperature of the hydraulic oil is relatively low, the line pressure does not correspond to the opening period even if the opening period of the solenoid valve provided in the line pressure forming unit is changed. The line pressure is no longer properly controlled, and the hydraulic pressure supplied to the speed change mechanism becomes too low or too high.
There is a possibility that a situation may occur in which the frictional engagement element built into the speed change mechanism causes undesired slippage or a situation in which a large speed change shock occurs. Therefore, when the temperature of the hydraulic oil is relatively low, the control for changing the line pressure is not performed,
It can be considered that the maximum line pressure is formed in the line pressure forming portion, but when the temperature of the hydraulic oil is relatively low,
When the line pressure forming portion is configured to form the maximum line pressure, undesired slippage of the friction engagement element is avoided, but when the gear range and the gear position are changed. There is a risk that the shift shock cannot be sufficiently suppressed.

In view of such a point, the present invention provides the following advantages even when the temperature of the hydraulic oil that causes the line pressure supplied to the speed change mechanism is relatively low.
To provide a hydraulic control device for an automatic transmission capable of adjusting a line pressure so as not to cause a situation in which an undesired slip occurs in a friction engagement element and a situation in which a large shift shock occurs. With the goal.

(Means for Solving the Problems) In order to achieve the above-mentioned object, a hydraulic control device for an automatic transmission according to the present invention has a hydraulic pressure generation source provided in the automatic transmission, as its basic configuration is shown in FIG. Hydraulic pressure obtained by adjusting the line pressure from the line pressure forming unit so that the line pressure forming unit that adjusts the hydraulic pressure from the line pressure forming unit and the transmission mechanism provided in the automatic transmission perform the gear shifting operation. To
An operating hydraulic pressure supply unit that selectively supplies a plurality of friction engagement elements built into a speed change mechanism, an oil temperature detecting unit that detects a temperature of hydraulic oil that causes a line pressure, and an engine connected to an automatic transmission. Load detecting means for detecting the load of the load and the control means, and the control means detects the load in the line pressure forming part when the temperature of the hydraulic oil detected by the oil temperature detecting means is below a predetermined value. A maximum line pressure is formed when the load detected by the means is greater than a predetermined value, and a minimum line pressure is formed when the load detected by the load detection means is equal to or less than the predetermined value. Be configured.

(Embodiment) FIG. 2 shows an example of a hydraulic control device for an automatic transmission according to the present invention, together with an automatic transmission for a vehicle to which the hydraulic control device is applied.

In FIG. 2, the automatic transmission 10 includes a torque converter 14 and a multi-stage gear type speed change mechanism 20, and is additionally provided with a hydraulic circuit section 40 that generates a hydraulic pressure used for operation control of these. .

The torque converter 14 includes a pump impeller 14a, a turbine runner 14b, a stator 14c, and a case 11.
An oil pump 15 is connected via a pump drive shaft 16 to the output shaft 12 of the engine to which the pump impeller 14a is connected. Turbine runner 14b
Is coupled to the speed change mechanism 20 via the hollow turbine shaft 17 and to the output shaft 12 via the lockup clutch 19, and the stator 14c and the case 11 are connected together.
A one-way clutch 18 is interposed between and, and the stator 14c is configured to rotate in the same direction as the pump impeller 14a and the turbine runner 14b.

The speed change mechanism 20 includes a planetary gear unit 21 for obtaining four forward gears and one reverse gear. The planetary gear unit 21 includes a small-diameter sun gear 22, a large-diameter sun gear 23,
Long pinion gear 24, short pinion gear 25,
And a ring gear 26. A forward clutch 27 for forward traveling and a coasting clutch 28 are provided in parallel between the small-diameter sun gear 22 and the turbine shaft 17, and the small-diameter sun gear 22 and the forward clutch 2 are arranged.
A one-way clutch 29 is interposed between the two and seven. A reverse clutch 30 for reverse traveling is provided between the large-diameter sun gear 23 and the turbine shaft 17, a 2-4 brake 31 is provided, and between the long pinion gear 24 and the turbine shaft 17. Is provided with a 3-4 clutch 32. The long pinion gear 24 is connected to a transmission case 35 via a carrier 33 and a one-way clutch 34, and the carrier 33 and the transmission case 35 are disengaged by a low reverse brake 36. The ring gear 26 is connected to the output gear 38 via the output shaft 37 of the automatic transmission 10.
The torque obtained by the output shaft 37 is transmitted to the front wheels, which are driving wheels of the vehicle, via a differential gear unit (not shown) or the like.

In the multi-stage gear type speed change mechanism 20 having such a configuration, the forward clutch 27, the coasting clutch 28, the reverse clutch 30, 2- which are friction engagement elements.
The 4 brake 31, the 3-4 clutch 32, and the low reverse brake 36 are appropriately selected and operated, so that the P range (parking range), the R range (reverse range), the N range (neutral range), and
It is possible to obtain each range of the D range, the S range (2 ranges), and the L range (1 range) that configure the forward range, and the first to fourth speeds in the forward range. The clutches 27, 28, 32 and 30, and the brake 3 for obtaining the respective ranges and gears
The table shows the operating relationship between 1 and 36 and the operating states of the one-way clutches 29 and 34 when the respective ranges and shift speeds are obtained.

The clutches 27,
The hydraulic pressures for operating the respective brakes 28, 32 and 30 and the brakes 31 and 36 are formed in the hydraulic circuit section 40, and the control unit 100 for controlling the operation of the hydraulic circuit section 40 is provided.

The control unit 100 includes a detection signal St obtained from a throttle opening sensor 51 for detecting the throttle opening in the intake passage of the engine and a turbine rotation speed sensor 52 for detecting the rotation speed (turbine rotation speed) of the turbine runner 14b. A detection signal Sr obtained and a detection signal Sv obtained from a vehicle speed sensor 53 for detecting the vehicle speed,
The detection signal Ss obtained from the shift position sensor 54 detecting the operation position of the shift lever 55 and the detection signal Su obtained from the oil temperature sensor 56 detecting the temperature of the hydraulic oil in the hydraulic circuit unit 40 are supplied, and Other signals Sx necessary for controlling the automatic transmission 10 are also supplied.

The control unit 100 performs shift control and lockup control in the automatic transmission 10 based on the above detection signals.

When the shift control and the lockup control are performed by the control unit 100, the control unit 1
In the shift pattern diagram as shown in FIG. 3, which is represented by mapping the throttle opening TH on the vertical axis and the vehicle speed V on the horizontal axis, which is mapped and stored in the built-in memory of 00, Lines La, Lb, Lc, Ld,
Le and Lf are collated with the throttle opening degree represented by the detection signal St and the vehicle speed represented by the detection signal Sv to determine whether or not the shift-up condition or the shift-down condition is satisfied, and the lock-up operation line Lg. And L
i, and the lockup release lines Lh and Lj are compared with the throttle opening represented by the detection signal St and the vehicle speed represented by the detection signal Sv to determine whether the lockup operation condition or the lockup release condition is satisfied. To be judged.

The shift lines La, Lb and L shown in FIG.
c is an upshift from 1st speed to 2nd speed, 2nd speed to 3rd speed, 3rd speed to 4th speed, and shift lines Ld, Le and Lf are 2nd speed to 1st speed, respectively. From 3rd to 2nd, 4
The present invention relates to downshifting from the third speed to the third speed. Further, the lockup operation lines Lg and Li are for lockup operation in the third speed and fourth speed states, and the lockup release lines Lh and Lj are for the lockup operation lines. The present invention relates to release of lockup in the 3rd and 4th speeds.

The control unit 100 then shifts the shift lines La and L in the shift pattern diagram as shown in FIG.
b, Lc, Ld, Le and Lf, and detection signals St and S
If it is determined that the up-shift condition or the down-shift condition is satisfied based on the comparison result between the throttle opening degree represented by v and the vehicle speed, the drive signal Ca,
Cb, Cc and Cd are formed, and they are connected to the hydraulic circuit unit 4
Solenoid valve 6 provided in the operating hydraulic pressure supply unit at 0
1, 62, 63 and 64 are supplied selectively. As a result, the operating states of the various shift valves and the like provided in the hydraulic pressure supply unit are changed, and the hydraulic pressure supply / discharge control for each of the plurality of friction engagement elements is performed. As shown, it is selectively engaged or disengaged to achieve the desired gear.

Further, the control unit 100 has lockup operation lines Lg and Li and lockup release lines Lh and L in the shift pattern diagram as shown in FIG.
When it is determined that the lock-up operation condition is satisfied based on the result of the comparison between j and the throttle opening and vehicle speed represented by the detection signals St and Sv, the drive signal Ce is formed and the drive signal Ce is formed. The hydraulic pressure is supplied to the solenoid valve 65 provided in the operating hydraulic pressure supply unit in the section 40, and when it is determined that the lockup release condition is satisfied, the supply of the drive signal Ce to the solenoid valve 65 is stopped. It As a result, the lockup clutch 19 of the plurality of friction engagement elements is locked by the lockup operation line Lg.
, Li, and lock-up release lines Lh and j, the engagement state and the release state are selectively set.

Further, the control unit 100 includes the hydraulic circuit unit 4
In order to change the line pressure at 0 as described later, the solenoid valve 66 built in the line pressure forming section of the hydraulic circuit section 40 is driven with a pulse width according to the duty set as described later. The signal Cf is supplied to perform control for adjusting the line pressure which is the basis of the operating hydraulic pressure formed in the hydraulic circuit section 40.

An example of the hydraulic control device for an automatic transmission according to the present invention having such a configuration is particularly characterized by control for adjusting the line pressure, and the hydraulic pressure control device as shown in FIG. Line pressure forming unit 44 in the circuit unit 40
It will be described based on the specific configuration of. In FIG. 4, the line pressure forming portion 44 is connected to the oil pump 15 via an oil passage 71.
Regulator valve 72 and reducing valve 73 connected to the regulator valve 72 and reducing valve 7
3 and a modulator valve 75 disposed between the valve 3 and a normally closed solenoid valve 66 for controlling the operation of the modulator valve 75.
It is assumed to have and.

In the line pressure forming unit 44, the hydraulic pressure discharged from the oil pump 15 is supplied to the reducing valve 73 through the oil passage 71 and is reduced by the reducing valve 73 to have a predetermined value. The hydraulic pressure reduced by the reducing valve 73 is supplied to the port a of the modulator valve 75 through the oil passage 77a to which the oil passage 76 and the solenoid valve 66 are connected, and the oil passage 7a
Ports b and c in modulator valve 75 are also supplied through 6 and 77b. At this time, the hydraulic pressure supplied to the port a of the modulator valve 75 is the drive signal C
Solenoid valve 6 according to the pulse width of f
It can be changed according to the valve opening period of 6. Thereby,
The effective opening area of the ports b and c in the modulator valve 75 changes, and the reducing valve 73 moves to the port b.
And the hydraulic pressure supplied to c is adjusted. Then, the adjusted hydraulic pressure is guided to the port d and supplied to the port e, and is also supplied as a pilot pressure to the port f of the regulator valve 72 through the oil passage 80 to which the damper 78 is connected.

The regulator valve 72 includes two spools 72a and 72a.
b and a spring 72c arranged between them,
In addition to the port f, ports g and h and ports i, j, and k connected to the oil passages 81, 82, and 83 communicating with the hydraulic pressure supply unit 42 are provided. In the regulator valve 72, the effective opening areas of the ports g and h are changed in accordance with the pilot pressure adjusted according to the pulse width of the drive signal Cf and supplied to the port f through the oil passage 80. The hydraulic pressure available to them is adjusted to form the line pressure. Then, the line pressure is supplied from the ports g and h through the oil passage 85 and the branch passage thereof to the working hydraulic pressure supply unit 42, and the working hydraulic pressure supply unit 4
2 is adjusted according to the operating state of a shift valve or the like provided therein, or is selectively supplied as it is as operating hydraulic pressure to a plurality of friction engagement elements, whereby a shift operation in the automatic transmission 10 is performed. And the lockup operation is performed.

With such a configuration, in the line pressure control performed by the control unit 100, the temperature (oil temperature) of the hydraulic oil in the hydraulic circuit section 40 represented by the detection signal Su.
Is higher than a predetermined value W ₁ , for example, −10 ° C., the steady line pressure control is performed during the steady state in which the automatic transmission 10 does not perform the shift operation, and the automatic transmission 10 performs the shift operation. During the gear shift, the shift line pressure control is performed.

In the steady line pressure control, the basic line pressure is set based on the throttle opening and the vehicle speed represented by the detection signals St and Sv, and the set basic line pressure and the detection signal Su are set.
The duty Dp that determines the pulse width of the drive signal Cf is set based on the oil temperature represented by the above. In that case, the duty Dp is set to take a larger value as the basic line pressure is lower and the oil temperature is higher.

In the shift line pressure control, the throttle opening and the vehicle speed V represented by the detection signals St and Sv, and the shift line in the shift pattern diagram as shown in FIG. 3 stored in the built-in memory of the control unit 100. La, L
b, Lc, Ld, Le and Lf are collated with each other to determine whether the up-shift condition or the down-shift condition is satisfied. When it is determined that the shift-up condition is satisfied, the mode of the shift operation to be performed according to the satisfied shift-up condition is 1st speed to 2nd speed, 1st speed to 3rd speed, 1st speed to 4th speed. To the second speed, the second speed to the third speed, the second speed to the fourth speed, and the third speed to the fourth speed, and the throttle opening indicated by the detection signal St. A basic line pressure is set for each mode of gear shifting operation. In that case, the basic line pressure is
The larger the throttle opening represented by the detection signal St, the larger the value set.

Further, when it is determined that the downshift condition is satisfied, the mode of the shift operation to be performed according to the established downshift condition is from the 4th speed to the 3rd speed, from the 4th speed to the 2nd speed, or from the 4th speed to the 1st speed. To the third speed, the third speed to the second speed, the third speed to the first speed, and the second speed to the first speed, and the turbine speed represented by the detection signal Sr. A basic line pressure is set for each mode of gear shifting operation. In that case, the basic line pressure is set to a larger value as the turbine rotation speed represented by the detection signal Sr is larger.
Then, with respect to the set basic line pressure, the change rate ΔTH of the throttle opening as shown in FIG. 5 has a predetermined value Δa ₁
Below, the larger the change rate ΔTH, the larger the value,
When the rate of change ΔTH is equal to or greater than the value Δa ₁ , the correction coefficient K having a constant value is multiplied to set a new basic line pressure. In this way, after the basic line pressure during shifting is set under the condition that the oil temperature is higher than the value W ₁ , the set basic line pressure and the oil represented by the detection signal Su are the same as in the steady state. The duty Dp that determines the pulse width of the drive signal Cf is set based on the temperature. In that case, the duty Dp
Is set to a larger value as the basic line pressure and the oil temperature are higher.

The duty Dp set in this way depends on the time t from the time t ₁ when the ignition key is turned on to the time t ₂ when a predetermined period Ta elapses, as shown in FIG. Is set to a different value, and after the period Ta has elapsed, the correction coefficient Hk set to 1 is multiplied to perform correction. Such a correction is caused because air is mixed in the hydraulic oil in the hydraulic circuit unit 40 immediately after the ignition key is switched from the off state to the on state, and therefore air is mixed. In order to prevent the line pressure and the operating hydraulic pressure in the hydraulic circuit unit 40 from becoming lower than required values. Next, the drive signal Cf having a pulse width corresponding to the duty DF obtained by correcting the duty Dp is formed, and is supplied to the solenoid valve 66, and the solenoid valve 66 responds to the pulse width of the drive signal Cf. The valve is opened only for a certain period, and the pilot pressure supplied to the port a of the modulator valve 75 through the oil passage 77a is reduced. Thereby, the line pressures obtained at the ports g and h of the regulator valve 72 are adjusted.

On the other hand, when the oil temperature represented by the detection signal Su is equal to or lower than the value W ₁ , the low oil temperature line pressure control is performed. In the low oil temperature line pressure control, as shown in FIG. 7, the throttle opening TH has a predetermined value ha such that the throttle opening TH is relatively small, for example,
When it takes a value equal to or less than 1/16 of the opening degree when fully opened, the drive signal Cf which is a constant level non-pulse signal is supplied to the solenoid valve 66, whereby the line pressure PL.
Is set to the minimum value Pmin, and when the throttle opening TH is larger than the value ha, the supply of the drive signal Cf to the solenoid valve 66 is stopped, which causes the line pressure PL to reach the maximum value. It is assumed to take Pmax.
In that case, when the throttle opening TH frequently changes near the value ha, the line pressure PL is the minimum value Pmin and the maximum value m.
Since there is a possibility that a so-called hunting phenomenon, which alternately takes ax and ax, may occur, the throttle opening TH is larger than the value ha and the value hb.
When the drive signal Cf, which is a constant level non-pulse signal, is supplied to the solenoid valve 66 immediately before when the following value, for example, a value that is 1/8 or less of the opening when fully opened is taken. Is continuously supplied to the solenoid valve 66, and the line pressure PL is the maximum value Pmax.
On the other hand, when the drive signal Cf which is a pulse signal immediately before that is sent to the solenoid valve 66 and when the drive signal Cf is not sent to the solenoid valve 66, the drive signal Cf is prevented from being sent to the solenoid valve 66, and the line pressure PL
Takes the minimum value Pmin.

By doing so, when the hydraulic oil used in the hydraulic circuit unit 40 is at a relatively low temperature and the load on the engine is relatively small, that is, when the throttle opening is relatively small. Since the line pressure is set to the minimum value, it is possible to reduce the shift shock due to the increase in the viscosity of the hydraulic oil, and to compare the torque generated by the engine when the engine load is relatively small. Since it is relatively small, the situation in which an undesired slippage occurs in each of the plurality of friction engagement elements is avoided, and when the engine load is relatively large, that is, the throttle opening is relatively large. At times, since the line pressure is set to the maximum value, the shortage of the working hydraulic pressure supplied to each of the plurality of friction engagement elements is resolved, and each of these friction engagement elements causes an undesired slip. That situation is avoided, the switching of the shift range and shift stage is to be ensured.

Control unit 10 that performs the control operation as described above
0 is configured by using a microcomputer, but in such a case, an example of a program for executing the line pressure control executed by the microcomputer,
This will be described with reference to the flowcharts of FIGS.

In the main program shown in the flowchart of FIG. 8, after start, initialization is performed in process 101, various detection signals are captured in process 102, and an ignition switch (IG switch) is turned from an off state to an on state in decision 103. If it is determined that the ignition switch has changed from the off state to the on state, the built-in timer is started in process 104, the process proceeds to decision 105, and the decision in decision 103 is made. As a result, if it is determined that the state of the ignition switch has not changed, so that it is already in the on state, the process proceeds to decision 105 as it is.

In the decision 105, it is determined whether the oil temperature W represented by the detection signal Su is less than or equal to the value W ₁ , and when it is determined that the oil temperature W is higher than the value W ₁ , in the decision 106, If it is determined that the flag F is 1, and if it is determined that the flag F is 1, the flag F is set to zero in the process 107, and the process proceeds to the decision 108. Further, in the decision 106, the flag F is set. If it is determined that F is not 1, the process proceeds directly to decision 108. And decision 1
At 08, it is determined whether or not the gear shifting operation is being performed. If it is determined that the gear shifting operation is not being performed, at process 109, the steady line pressure control program as shown in the flowchart of FIG. 9 is executed to execute the process. Back to 102,
When it is determined that the gear shifting operation is being performed, the gear shift line pressure control program as shown in the flowchart of FIG. 10 is executed in process 110, and the process returns to process 102. On the other hand, if the decision 105 determines that the oil temperature W is less than or equal to the value W ₁ , the process 112 executes the low oil temperature line pressure control program as shown in FIG. 11 to execute the process 102. Return to.

In the steady line pressure control program shown in the flowchart of FIG. 9, after the start, in process 121, the basic line pressure BL is set based on the throttle opening Th and the vehicle speed V represented by the detection signals St and Sv.
In the process 122, the basic line pressure BL and the oil temperature W
The duty Dp is set based on the
In 3, it is determined whether the period Tx that has passed since the ignition switch was started is longer than a predetermined period Ta, and if it is determined that the elapsed period Tx is less than or equal to the predetermined period Ta, In process 125,
When the correction coefficient Hk is set to a value smaller than 1 as shown in FIG. 6, the process proceeds to the process 128, and when it is determined that the elapsed period Tx is larger than the predetermined period Ta, , The timer is stopped in process 126, the correction coefficient Hk is set to 1 in process 127, and the process proceeds to process 128. In the process 128, the duty DF that determines the pulse width of the drive signal Cf
Is set to a value obtained by multiplying the duty Dp set in the process 122 by the correction coefficient Hk, and in a process 129, a drive signal Cf having a pulse width corresponding to the duty DF is formed and sent to the solenoid valve 66. Quit this program.

In the shift line pressure control program shown in the flowchart of FIG. 10, after the start, the decision 14
In step 1, it is determined whether the shift operation is the upshift operation. If it is determined that the upshift operation is the upshift operation, in process 142, based on the mode of the upshift operation and the throttle opening Th represented by the detection signal St. After setting the basic line pressure BL, the process proceeds to the process 147. On the other hand, if the decision 141 determines that the shift-up operation is not performed, that is, if the shift operation is the shift-down operation, the process 144 is performed.
, The basic line pressure B based on the mode of shift-down operation and the turbine speed Nt represented by the detection signal Sr.
L is set, and in the process 145, the correction coefficient K is set to
As shown in FIG. 5, a new basic line pressure BL is set by setting in accordance with the rate of change ΔTH of the throttle opening TH and proceeding to process 146, in which the basic line pressure BL is multiplied by the correction coefficient K. Is set and the process proceeds to process 147. Then, the steps from the process 147 to the process 153 are executed in the same manner as the steps from the process 122 to the process 129 in the steady line pressure control shown in FIG. 9, and the program is ended.

In the low oil temperature line pressure control program shown in the flowchart of FIG. 11, after the start, in the decision 161, it is determined whether the throttle opening Th represented by the detection signal St is equal to or less than the value ha, and the throttle opening is performed. When it is determined that the degree Th is less than or equal to the value ha, the decision 162 determines whether or not the flag F is 1, and when it is determined that the flag F is not 1, the flag is set in the process 163. When F is set to 1, the process proceeds to the process 164, and when it is determined in the decision 162 that the flag F is 1, the process proceeds to the process 164 as it is. And process 164
Drive signal Cf which is a constant level non-pulse signal in
And sends it to solenoid valve 66 to end the program. On the other hand, in the decision 161, the throttle opening Th represented by the detection signal St is the value h.
If it is determined to be greater than a, the decision 1
At 65, it is determined whether or not the throttle opening Th represented by the detection signal St is equal to or less than the value hb. If it is determined that the throttle opening Th is equal to or less than the value ha, the flag F is changed in the process 166. If it is determined that the flag F is 1, the process 164 is executed in the same manner as described above, and the program is terminated. When it is determined in the decision 165 that the throttle opening Th represented by the detection signal St is larger than the value hb, it is determined in the decision 167 whether or not the flag F is 1, and the flag F is 1 If the flag F is determined to be zero in process 168, and the program is terminated in decision 167, and if the flag F is determined to be zero in decision 167, and decision 166 is performed.
If it is determined that the flag F is not 1,
This program ends as it is.

(Effect of the Invention) As is apparent from the above description, according to the hydraulic control device for an automatic transmission according to the present invention, the load of the engine is relatively small while the oil temperature is below a predetermined value. Sometimes, the line pressure is set to the minimum value, so it is possible to reduce the shift shock due to the increase in the viscosity of the hydraulic oil, and when the engine load is relatively small, the engine is generated. Since the torque to perform is relatively small,
It is possible to avoid a situation in which undesired slippage occurs in each of the plurality of friction engagement elements incorporated in the speed change mechanism. Also,
When the engine temperature is lower than a predetermined value and the engine load is relatively large, the line pressure is set to the maximum value, so the operation supplied to each of the plurality of friction engagement elements is performed. It is possible to effectively avoid a situation in which the insufficient hydraulic pressure is eliminated and undesired slippage occurs in each of the friction engagement elements.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a hydraulic control device for an automatic transmission according to the present invention corresponding to the scope of claims for utility model registration, and FIG. 2 is a main example of a hydraulic control device for an automatic transmission according to the present invention. FIG. 3 is a diagram schematically showing the parts, FIG. 3 is a shift pattern diagram used for explaining the operation of the example shown in FIG. 2, and FIG. 4 is a main part of the hydraulic circuit part in the example shown in FIG. 5 to 7 are characteristic diagrams for explaining the operation of the example shown in FIG. 2, and FIGS. 8 to 11 are microcomputers in the control unit of the example shown in FIG. It is a flow chart which shows an example of a program which such a microcomputer runs when used. In the figure, 10 is an automatic transmission, 14 is a torque converter, and 2
Reference numeral 0 is a speed change mechanism, 40 is a hydraulic circuit portion, 42 is an operating hydraulic pressure supply portion, 44 is a line pressure forming portion, 51 is a throttle opening sensor, 56 is an oil temperature sensor, 66 is a solenoid valve, 72 is a regulator valve, and 75 is a regulator valve. A modulator valve, 100 is a control unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Takemoto 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) Bibliography Sho 61-133150 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A line pressure forming portion for adjusting a hydraulic pressure from a hydraulic pressure source provided in an automatic transmission to form a line pressure, and a transmission mechanism provided in the automatic transmission for performing a shift operation. An operating hydraulic pressure supply unit that selectively supplies an operating hydraulic pressure obtained by adjusting the line pressure from the line pressure forming unit to a plurality of friction engagement elements built in the transmission mechanism, and an operation that generates the line pressure. An oil temperature detecting means for detecting the temperature of the oil; a load detecting means for detecting the load of the engine connected to the automatic transmission; and a line pressure forming part for detecting the operating oil detected by the oil temperature detecting means. When the temperature detected is below a predetermined value and the load detected by the load detection means is higher than a predetermined value, the maximum line pressure is formed, and the load detected by the load detection means is set to the predetermined value. Is less than or equal to And a control means for forming a minimum line pressure, and a hydraulic control device for an automatic transmission, comprising: