JP3007646B2 - Hydraulic control device for continuously variable transmission - Google Patents

Description

The present invention relates to a hydraulic system for supplying a predetermined hydraulic pressure to a primary cylinder and a secondary cylinder, a forward / reverse switching device, a torque converter, and the like in a belt-type continuously variable transmission for a vehicle. More specifically, the present invention relates to variable control of an oil pump oil amount.

[Conventional technology]

Generally, a vehicle equipped with a continuously variable transmission includes an oil pump driven by an engine and a hydraulic pressure source. The pump discharge pressure is regulated to generate a secondary pressure, and the secondary pressure is used to generate a primary pressure. The hydraulic control device is configured to obtain the lubrication pressure and various operating pressures. Here, the secondary pressure is controlled in a wide range, and a large amount of oil is required at a time during a sudden upshift and downshift. Therefore, a high-pressure high-discharge-type oil pump is used. By the way, during steady running with a constant gear ratio, a large amount of oil is drained by the control valve due to the small amount of oil used, so that the pump load becomes large in a high-pressure, high-discharge oil pump, which has an adverse effect on fuel efficiency and the like. ing. For this reason, it has been considered to variably control the oil pump oil amount to reduce the pump loss when the used oil amount is small.

Conventionally, there is a prior art in Japanese Patent Application Laid-Open No. 61-215853, for example, regarding variable control of the oil pump oil amount of the continuously variable transmission. Here, the first, driven by the engine
It has a second hydraulic pump, and the discharge side of the second hydraulic pump communicates with the discharge side of the first hydraulic pump via a check valve and recirculates to the hydraulic tank via an electromagnetic switching valve. When the speed ratio changes rapidly at low engine speeds, the controller closes the electromagnetic switching valve to operate the second hydraulic pump under load, and otherwise opens the electromagnetic switching valve to recirculate oil. This indicates that the vehicle is operated without load.

[Problems to be solved by the invention]

By the way, in the above-mentioned prior art, since there are two hydraulic pumps, a mounting place, a drive system and the like are complicated. In addition, since only the shortage of hydraulic oil on the side of the continuously variable transmission is detected and controlled, sufficient oil management cannot be performed. That is, other devices that use oil, such as a torque converter, a lock-up clutch, and a forward / reverse switching device, are also disposed in the drive system of the continuously variable transmission, and the hydraulic control system controls the hydraulic pressure including these components. Therefore, the required oil amount needs to be determined in consideration of all the components such as the continuously variable transmission and the torque converter, and it is necessary to control the oil pump oil amount so as not to be insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the number of oil pumps and control the hydraulic pressure of a continuously variable transmission capable of optimally variably controlling the oil pump oil amount. It is to provide a device.

[Means for solving the problem]

In order to achieve the above object, a hydraulic control device for a continuously variable transmission according to the present invention is a hydraulic device for a drive system combining a continuously variable transmission with a torque converter and a hydraulic forward / reverse switching device,
The oil pump device of the hydraulic device has a plurality of discharge ports,
In a hydraulic control device of a continuously variable transmission in which a discharge port other than one of the discharge ports is controllably connected to a load and a no-load operation by a check valve and a solenoid valve, the control unit of the hydraulic control device includes: A continuously variable transmission required oil amount calculating means for calculating a required oil amount on the continuously variable transmission side of the drive system, and a torque converter side required oil amount calculation for calculating a required oil amount on the torque converter side excluding the above continuously variable transmission. Means, a pump oil amount calculating means for calculating the discharge oil amount of the entire oil pump, and all necessary oil of the drive system calculated by the continuously variable transmission necessary oil amount calculating means and the torque converter side necessary oil amount calculating means. Comparing means for comparing the oil amount of the oil pump with the entire oil pump and judging the discharge port of the oil pump for load operation, and inputting the output of the comparing and judging means to the solenoid valve. It is characterized by having a configuration.

[Action]

Based on the above configuration, the oil pump is constantly driven to rotate during the operation of the engine to generate a discharge hydraulic pressure. The discharge hydraulic pressure is guided to a hydraulic control system such as a continuously variable transmission or a torque converter to perform various controls. In this case, the control unit calculates not only the shift control of the continuously variable transmission but also the required oil amount of the torque converter and the like, and further calculates the total pump oil amount according to the engine speed and the like. The plurality of discharge ports are selectively operated under load, so that the pump oil amount is always controlled to an appropriate value substantially matching the required oil amount.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2, an outline of the drive system of the continuously variable transmission with a lock-up torque converter will be described. Reference numeral 1 denotes an engine, and a crankshaft 2 is sequentially transmitted to a torque converter device 3, a forward / reverse switching device, a continuously variable transmission 5, and a differential device 6.

In the torque converter device 3, the crankshaft 2 is connected to the converter cover 11 and the pump impeller 12 a of the torque converter 12 via the drive plate 10. A turbine runner 12b of the torque converter 12 is connected to a turbine shaft 13, and a stator 12c is guided by a one-way clutch 14. A lock-up clutch 15 integrated with the turbine runner 12b is provided so as to be engaged with or released from the drive plate 10, and transmits engine power via the torque converter 12 or the lock-up clutch 15.

The forward / reverse switching device 4 includes a double pinion type planetary gear 16. The turbine shaft 13 is input to the sun gear 16 a and output from the carrier 16 b to the primary shaft 20. A forward clutch 17 is provided between the sun gear 16a and the carrier 16b.
The reverse brake 1 between the ring gear 16c and the case.
The planetary gear 16 is integrated with the forward shaft 17 to directly connect the turbine shaft 13 and the primary shaft 20. Also, the reverse power is output to the primary shaft 20 by the engagement of the reverse brake 18, and the forward clutch 17 is output.
And the release of the reverse brake 18 makes the planetary gear 16 free.

The continuously variable transmission 5 includes a primary pulley 22 having a hydraulic cylinder 21 on a primary shaft 20 and a variable pulley interval, and a secondary pulley 25 having a hydraulic cylinder 24 on a secondary shaft 23. A drive belt 26 is wound around the pulley 25. Here, the pressure receiving area of the primary cylinder 21 is set larger, and the ratio of the winding diameter of the drive belt 26 to the primary pulley 22 and the secondary pulley 25 is changed by the primary pressure to perform stepless transmission.

In the differential device 6, an output shaft 28 is connected to the secondary shaft 23 via a pair of reduction gears 27, and a drive gear 29 of the output shaft 28 meshes with the final gear 30. A differential gear 31 of the final gear 30 is connected to left and right wheels 33 via an axle 32.

On the other hand, an oil pump 34 is provided adjacent to the torque converter 12 in order to obtain a hydraulic source for controlling the continuously variable transmission, and the oil pump 34 is connected to the converter cover 11 by a pump drive shaft 35 so that the engine power To be driven.

 In FIG. 1, the hydraulic control system will be described.

First, regarding the hydraulic control system of the continuously variable transmission, an oil passage 51 from an oil pump device 46 communicating with an oil pan 50 will be described.
Communicates with the secondary pressure control valve 52 to
Ps is generated, and the secondary pressure Ps is always supplied to the secondary cylinder 24 through the oil passage 53. Secondary pressure Ps
Is guided to the primary pressure control valve 56 through an oil passage 55,
57 is configured to supply and discharge oil to the primary cylinder 21 to generate a primary pressure Pp.

The oil pump 34 of the oil pump device 46 is of a variable displacement type having a plurality of sets of suction and discharge ports of a roller vane type.
A case where three sets of suction and discharge ports are provided will be described. In this case, the cam ring 36 has a triangular hydraulic chamber 36a.
And a rotor 37 connected to the drive shaft 35 at the center of the inside of the hydraulic chamber 36a. A plurality of vanes 38 are provided around the rotor 37. In three bulging portions of the hydraulic chamber 36a, suction ports 39a, 39b, and 39c are provided on the leading side in the rotation direction of the rotor, and discharge ports 40a, 40b, and 40c are provided on the lagging side. It is possible to vary the amount of oil within about two or three times.

Each of the suction ports 39a, 39b, and 39c communicates with the oil pan 50 via the oil path 41, and one discharge port 40a communicates with the oil path 51, so that load operation is always performed. On the other hand, the other discharge ports 40b and 40c
2a and 42b communicate with the oil passage 51 through the check valves 43a and 43b, and at the same time, the oil pan 50 through the solenoid valves 44a and 44b.
Side, so that load or no-load operation can be selected.

The secondary pressure control valve 52 is a proportional solenoid relief valve, and the control unit 90 supplies a solenoid current Is to the proportional solenoid 52a. Then, the electromagnetic force due to the solenoid current Is, the hydraulic reaction force of the secondary pressure Ps, and the spring force act on the spool so as to balance them. That is, the set pressure is made variable by the solenoid current Is, and the secondary pressure Ps is controlled in a one-to-one proportional relationship with the solenoid current Is.

The primary pressure control valve 56 is a proportional electromagnetic relief valve, and like the secondary pressure control valve 52, the control unit 90 controls the proportional solenoid solenoid 56a by the solenoid current Ip.
Is supplied. Then, the electromagnetic force by the solenoid current Ip, the hydraulic reaction force of the primary pressure Pp, and the spring force act on the spool so that the set pressure is made variable by the solenoid current Ip, and the one-to-one proportionality to the solenoid current Ip is obtained. The primary pressure Pp is controlled by the relationship. Here, the hydraulic pressure of the drain-side oil passage 58 of the secondary pressure control valve 52 is relatively high, and can be used not only for lubrication but also for a torque converter, an operating pressure for switching between forward and backward, and a control pressure. Therefore, the lubricating pressure oil passage 58 communicates with the hydraulic relief valve 59 to provide a predetermined lubricating pressure.
Pl is generated, and an oil passage 60 branched from the lubrication pressure oil passage 58 communicates with a nozzle 62 via a check valve 61 to supply oil to the belt 26.

Next, a hydraulic control system such as a torque converter will be described.

The lubrication pressure oil passage 58 communicates with the two input sides of the lock-up control valve 63 and one control side, and the oil passage 65 of the control pressure Pc of the lock-up control solenoid valve 64 that uses the lubrication pressure as the base pressure is The lock-up control valve 63 communicates with the other control side. The oil passage 66 on one outlet side of the lock-up control valve 63 communicates with the release chamber 15a of the lock-up clutch 15, and the oil passage 67 on the other outlet side has a relief valve 68, Apply room 15b for lock-up clutch 15
Communicate with Also, when the torque converter 12 operates, the oil passage
A drain side oil passage 69 communicating with 67 is in communication with an oil cooler 70, and a control pressure oil passage 65 of the solenoid valve 64 is further in communication with a hydraulic relief valve 59, and when a control pressure Pc is generated during lock-up, the hydraulic relief valve 59 Is set to a lower pressure.

On the other hand, the secondary pressure oil passage 51 and the lubrication pressure oil passage 58 communicate with the forward clutch 17 and the reverse brake 18 via the safety lock valve 71, the oil passages 72 and 73, the manual valve 74, and the oil passages 75 and 76. . The control side of the Deposit lock valve 71, the control pressure P _SL solenoid valve 77 to source pressure lubrication pressure is led through the oil passage 78, to force the oil passage 72 or 73 so as to drain I have. The manual valve 74 switches the oil passage according to each shift operation. In the parking (P) and neutral (N) ranges, the oil passages 75 and 76 are drained together.
In the D range, the forward clutch is connected by communication between the oil passages 72 and 75.
Supply lubrication pressure Pl to 17. On the other hand, in the R range,
High secondary pressure Ps for reverse brake 18 through communication with 76
To increase the torque capacity, and to engage and fix both the input and output torque reaction forces acting on the ring gear side.

In the middle of the oil passage 75 to the forward clutch 17, an accumulator 83 communicates via an oil passage 82 in which an orifice 80 and a check valve 81 are arranged in parallel.
The accumulator acts so as to gradually engage when refueling. Further, an accumulator 85 communicates with an oil passage 76 to the reverse brake 18 via an oil passage 84 having a similar orifice 80 and a check valve 81, and also acts as an accumulator.

Further, the drain side of the hydraulic relief valve 59 has an orifice 86
The oil passage 87 communicates with the suction side of the oil pump 34 via an oil passage 87, and communicates with the oil cooler 70 via an oil passage 89 having an oil cooler valve 88. And torque converter 12
When the lock-up is inoperative, a large amount of oil drained from the hydraulic relief valve 59 can be guided to the oil cooler 70 to be cooled.

Note that a lock-up signal based on the ratio of the input and output rotational speeds of the torque converter 12 and the like is input from the control unit 90 to the solenoid valve 64. A power transmission cutoff signal at the time of an incorrect shift operation is input to the solenoid valve 77.

In FIG. 3, an oil pump control system in the control unit 90 will be described.

First, the required oil amount on the continuously variable transmission 5 side will be described.
Oil is constantly supplied to the secondary cylinder 24, and during shift control, oil is supplied to and discharged from the primary cylinder 21 during an upshift.
What is necessary is just to obtain the required oil amount from the state of oil supply and discharge to 21. Also,
At the time of the downshift, the oil is supplied to the secondary cylinder 24, so the required oil amount may be obtained from the state of the oil supplied to the secondary cylinder 24. The supply and discharge of oil to and from the primary cylinder 21 depends on the shift speed di / dt of the shift control system and the target speed ratio change speed di.
s / dt and the primary pressure when converting to flow rate
Pp and secondary pressure Ps are used. Therefore, there is provided a continuously variable transmission required oil amount calculation unit 95 to which the shift speed di / dt of the shift control system, the target gear ratio change speed dis / dt, the primary pressure Pp, and the secondary pressure Ps are input. The required oil amount Qc is calculated based on the cylinder pressure receiving area and the like. Secondary cylinder 24
The amount of refueling is calculated in the same manner.

Next, the required oil amount of the torque converter 12 and the like will be described. The torque converter-side required oil amount calculation unit 96 receives the lock-up signal, the shift position signal, and the lubricating pressure Pl of the lubricating pressure sensor 91. The amount of oil according to the presence or absence of the lockup, the oil amount required for clutch or brake of the forward-reverse switching, the amount of lubricating oil by the lubricant pressure Pl, calculates the required oil amount Q _L by the oil cooler oil amount, etc..

On the other hand, the amount of oil generated in the oil pump 34 is determined by the engine speed Ne, the discharge pressure P ₀ , and the oil temperature T ₀ , so that the engine speed Ne, the discharge pressure P _0, and the oil temperature T ₀ of the oil temperature sensor 92 are determined. Has a pump oil amount calculation unit 97 to which the input is performed. And the engine speed Ne,
The total oil amount Qn on the pump side is calculated from the discharge pressure P ₀ and the oil temperature T _{0. In} this case, the oil amounts to the three sets of discharge ports are Q ₁ , Q ₂ ,
For the Q _3, it becomes _{Qn = Q 1 + Q 2 +} Q 3.

And these oil amount Qc, Q _L, Qn is input to the comparison determination unit 98,
Total required oil amount Qc + Q _L and the pump oil amount Qn is compared. Here, as for the pump oil amount Qn, as shown in FIG. 4, Q ₁ in the case of one discharge port 40a and Q ₁ + in the case of two discharge ports 40a, 40b.
Q _2, 3 two discharge ports 40a, 40b, 40c Q ₁ + characteristics of Q ₂ + Q ₃ is set in the case of, sufficient only total required oil amount Qn = Qc + Q _L is the discharge port 40a point C _1. At point C ₂ , two discharge ports 4
0a, refueled at 40b, point C ₃ at three discharge ports 40a, 40b, it is determined that it is sufficient lubrication at 40c. The selection signal is output to the solenoid valves 44a and 44b via the output unit 99.

Next, the operation of the hydraulic control device for a continuously variable transmission having such a configuration will be described.

First, the operation of the engine 1 causes the torque converter 12
The oil pump 34 is driven to rotate via the converter cover 11 and the drive shaft 35. When the vane 38 moves in and out together with the rotor 37 by the oil pump 34, the oil is sucked in from three suction ports 39a, 39b, and 39c, and is pressurized by the vane 38 to be discharged in three discharge ports 40a, 40b. , 40
Discharged from c. The hydraulic pressure discharged from one discharge port 40a is directly guided to a secondary pressure control valve 52 via an oil passage 51, while the hydraulic pressure discharged from the other two discharge ports 40b and 40c is changed by the continuously variable transmission. 5, is selectively supplied according to the required oil amount of the torque converter 12 and the like.

By the oil pump device 46, the pump discharge oil pressure supplied to the oil passage 51 is guided to the secondary pressure control valve 52 to regulate the pressure, and a predetermined high secondary pressure Ps is generated. Further, the hydraulic pressure in the drain-side oil passage 58 of the secondary pressure control valve 52 is guided to a hydraulic relief valve 59 to generate a constant lubricating pressure Pl, and this lubricating pressure Pl is supplied to each of the solenoid valves 64 and 77 for control. It is possible to generate a pressure Pc. Further, the secondary pressure Ps is always supplied to the secondary cylinder 54 to apply a necessary minimum pulley pressing force according to the transmission torque. The secondary pressure Ps is applied to the primary pressure control valve 56 and the manual valve 74.
Is led to. The lubricating pressure Pl is used for lubricating the belt 26, and is guided to the control side and the refueling side of the lock-up control valve 63, and to the manual valve 74.

Therefore, at the time of stopping and starting, the secondary pressure Ps is reduced most by the primary pressure control valve 56, and the primary pressure Pp of the primary cylinder 21 is controlled to the lowest level.
The belt 26 is the most secondary pulley in the continuously variable transmission 5.
It becomes the low speed stage with the maximum gear ratio shifted to 25. At this time, since the lock-up / off signal is input to the solenoid valve 64 and the control pressure Pc is controlled so as not to be generated, the lock-up control valve 63 operates to one side by the lubrication pressure Pl, as shown in the figure. The lubrication pressure Pl is led to the oil passage 66. Therefore, the lubricating pressure Pl enters the release chamber 15a of the lock-up clutch 15 via the oil passage 66 to turn off the lock-up clutch 15,
Circulation returns to the oil pan 50 via the torque converter 12, the oil passages 67 and 69, and the oil cooler 70, whereby the torque converter 12 is in an operating state.

The safety lock valve 71 guides the lubricating pressure Pl and the secondary pressure Ps to the oil passages 72 and 73 in a normal state.

Here, in the ranges P and N, the forward clutch 17 and the reverse brake 18 of the forward / reverse switching device 4 are both drained and released by the manual valve 74. As a result, the planetary gear 16 becomes free, and power transmission from the engine 1 to the continuously variable transmission 5 is cut off.

Then, when shifting to the D range, the lubricating pressure Pl of the oil passage 72 is supplied to the forward clutch 17 via the oil passage 75, and at this time, the accumulator 83 increases the volume and controls the rise of the oil pressure slowly. Forward clutch
17 smoothly engages the sun gear 16a and the carrier 16b to reach the forward position. As a result, the engine power is input to the primary shaft 20 via the torque converter 12 and the turbine shaft 13, and the fluctuating power is output to the secondary shaft 23 by the primary pulley 22, the secondary pulley 25, and the belt 26. The vehicle travels by transmitting it to the wheels 33 via the vehicle.

When the primary pressure control valve 56 increases the primary pressure Pp due to various driving and running conditions after the start, the belt
26 shifts to the direction in which the winding diameter of the primary pulley 22 becomes larger and shifts up, and conversely, shifts down by decreasing the primary pressure Pp. Thus, the shift control is performed. The secondary pressure control valve 52 variably controls the secondary pressure Ps based on the gear ratio, the engine torque, the torque ratio of the torque converter 12, and the like.

When the torque converter 12 enters the coupling region after the start of the shift, a lock-up / on signal is input to the solenoid valve 64 to generate a control pressure Pc, and the lock-up control valve 63
Is switched to guide the lubricating pressure Pl to the oil passage 67. Therefore, the lubricating pressure Pl acts on the apply chamber 15b of the lock-up clutch 15 via the torque converter 12, and the lock-up clutch 15 is engaged to enter the lock-up state. Therefore, in this case, the engine power is
, Which will be transmitted efficiently. On the other hand, the control pressure Pc is guided to the hydraulic relief valve 59, and by reducing the set pressure, a large amount of oil flows from the hydraulic relief valve 59 to the oil cooler 70 via the oil cooler valve 88 and is cooled.

Next, when shifting to the R range, the secondary pressure Ps is changed by the manual valve 74 to the reverse brake 1 by the oil passages 73 and 76.
The ring gear 16c of the planetary gear 16 of the forward / reverse switching device 4 is firmly fixed to the case side. For this reason, the reverse power is output to the primary shaft 20 via the carrier 16b to be in the reverse position, and the continuously variable transmission 5 and the subsequent components reversely rotate and travel backward. Also in this case, reverse brake
The rise of the secondary pressure Ps to 18 is made gentle by the accumulator 85, and the secondary pressure Ps is smoothly engaged so that the switching shock does not occur.

On the other hand, in the case of each control such as the above-mentioned shift control, lock-up, and forward / reverse switching, each of the calculation units 95 to
In 97, the CVT 5 and the required oil amount Qc of the torque converter 12 or the like, Q _L, and pump oil amount Qn is calculated, the comparison determination unit 98
Then, both are compared and judged. So when idling stop, required oil quantity Qc, Q _L is small, the engine speed N
When the pump oil amount Qn is also small due to e, the two solenoid valves 44a and 44b of the oil pump device 46 are closed by the output unit 99 based on the map of FIG. Therefore, three outlets 4
The discharge hydraulic pressure of 0a, 40b, 40c is supplied via check valves 43a, 43b. Next, when the pump oil amount Qn increases due to an increase in the engine speed Ne at the time of starting, for example, the solenoid valve 44b is opened, the discharge oil pressure of the discharge port 40c is recirculated, and no load is applied, and the two discharge ports 40a, 40b Refueled. On the other hand, when the shift is started and a large amount of oil is supplied to the primary cylinder 21 by the shift speed di / dt of the shift control system, the oil amount Qc increases,
When oil is discharged during a downshift will be the oil amount Qc is reduced further when the lock-up reduces the amount of oil Q _L. Accordingly, these oil required amount Qc, in relation to the pump oil amount Qn corresponding to the Q _L and the engine rotational speed Ne, the solenoid valve 44a, one or both of 44b are refueling closed. Here, in particular, in the steady running of the overdrive, necessary oil quantity Qc, that Q _L is the smallest pump oil amount Qn is large, it becomes possible to refueling only one outlet 40a.

Thus, three sets of discharge ports 40a, 40b, 40 of the oil pump 34
The discharge oil pressure c is selected and used, and optimal control is performed so that the required oil amount of the continuously variable transmission 5 and the torque converter 12 and the like is satisfied without excess or deficiency in relation to the pump oil amount.

The embodiments of the present invention have been described above. However, the present invention can be applied to a case having two sets of suction and discharge ports and a case having a plurality of oil pumps.

〔The invention's effect〕

As described above, according to the present invention, in the oil pump device of the hydraulic control system of the continuously variable transmission, the required oil amount of not only the continuously variable transmission but also the entire drive system such as the torque converter is obtained. Since the pump oil amount is variably controlled by comparing with the entire pump oil amount, the pump oil amount can be optimized most and the pump load can be effectively reduced.

Further, when a plurality of sets of suction and discharge ports are provided in the oil pump and disposed adjacent to the torque converter, the number of pumps is reduced, and the mounting space and the drive system are simplified, which is preferable.

Further, by using the signal of the shift control system for calculating the required oil amount and the pump oil amount, the control is also facilitated.

[Brief description of the drawings]

1 is a circuit diagram showing an embodiment of a hydraulic control device for a continuously variable transmission according to the present invention, FIG. 2 is a skeleton diagram showing a drive system of the continuously variable transmission, FIG. 3 is a block diagram of an electronic control system, FIG. 4 is a diagram showing the relationship between the required oil amount and the pump oil amount. 4. Forward / reverse switching device, 5 ... Continuously variable transmission, 12 ... Torque converter, 34 ... Oil pump, 39a, 39b, 39c ...
Suction port, 40a, 40b, 40c ... discharge port, 43a, 43b ... check valve, 44a, 44b ... solenoid valve, 46 ... oil pump device

Claims (1)

(57) [Claims] 1. A hydraulic system for a drive system in which a continuously variable transmission is combined with a torque converter and a hydraulic forward / reverse switching device.
The oil pump device of the hydraulic device has a plurality of discharge ports,
In a hydraulic control device of a continuously variable transmission in which a discharge port other than one of the discharge ports is controllably connected to a load and a no-load operation by a check valve and a solenoid valve, the control unit of the hydraulic control device includes: A continuously variable transmission required oil amount calculating means for calculating a required oil amount on the continuously variable transmission side of the drive system, and a torque converter side required oil amount calculation for calculating a required oil amount on the torque converter side excluding the above continuously variable transmission. Means, a pump oil amount calculating means for calculating a discharge oil amount of the entire oil pump, and a total oil required for the drive system calculated by the continuously variable transmission required oil amount calculating means and the torque converter side required oil amount calculating means. Comparing means for comparing the oil amount of the oil pump with the total amount of oil discharged from the oil pump to determine the discharge port of the oil pump that performs the load operation. The output of the comparing and judging means is input to the solenoid valve. A hydraulic control device for a continuously variable transmission, wherein