JP4317116B2 - Hydraulic control device for belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a hydraulic control device for a belt-type continuously variable transmission (CVT) that transmits torque by pressing a belt against a pulley, and in particular, a primary and a secondary pulley each have a piston chamber for shifting and a piston chamber for clamping. The present invention relates to a hydraulic control device for a double piston type CVT.

In a belt-type continuously variable transmission, a belt is held by a pulley capable of generating hydraulic thrust, and power is transmitted by a frictional force between the pulley and the belt. At this time, if the frictional force between the pulley and the belt is smaller than the belt driving force, belt slip may occur and the durability may be lowered. Therefore, in the double piston type CVT, a thrust generation chamber (piston chamber) for shifting and a thrust generation chamber (clamp chamber) for preventing belt slip are provided on the primary side and the secondary side, respectively, to avoid belt slip at the time of shifting. (For example, refer to Patent Document 1.)
JP 2002-327814 A

  However, in the above prior art, since the primary and secondary clamp chambers communicate with each other, the same clamping pressure always acts on each pulley. Therefore, when the higher hydraulic pressure of the primary side and secondary side pulley pressure is used as the clamp pressure, if the higher hydraulic pressure is not sufficiently secured due to the problem of the hydraulic response limit, the lower pressure is reduced as the clamp pressure decreases. There was a problem that the piston chamber hydraulic pressure was lowered beyond the slip limit, which could cause belt slip.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to prevent belt slipping and achieve stable gear shifting even when sufficient clamping pressure is not ensured due to the hydraulic response limit. It is an object of the present invention to provide an achievable hydraulic control device for a belt-type continuously variable transmission.

In order to achieve the above-mentioned object, in the present invention, a primary pulley having a primary piston chamber, a secondary pulley having a secondary piston chamber, a belt for transmitting power between the primary pulley and the secondary pulley by friction force, and the primary respectively provided on the pulley and the secondary pulley, introduced into the communicating path and primary clamp chamber and a secondary clamp chamber connected by communication paths from one another, the hydraulic of the higher oil pressure of the hydraulic and the secondary piston chamber of the primary piston chamber as a clamp pressure High pressure side selective introducing means, hydraulic pressure calculating means for calculating a target primary hydraulic pressure and a target secondary hydraulic pressure based on each target thrust of the primary pulley and the secondary pulley, and actual oil in the primary piston chamber and the secondary piston chamber If the actual hydraulic pressure detecting means for detecting the actual hydraulic pressure of the higher pressure side pulley of the target primary hydraulic and the target secondary hydraulic pressure is lower than the target hydraulic pressure of the high-pressure side pulley, due to the target hydraulic pressure of the high-pressure side pulley And a hydraulic pressure correction control means for calculating a difference between the thrust and the thrust due to the actual hydraulic pressure of the high-pressure pulley, and adding a hydraulic pressure corresponding to the difference to a target hydraulic pressure of the other low-pressure pulley .

  Therefore, it is possible to provide a hydraulic control device for a belt-type continuously variable transmission that can prevent a belt slip and achieve a stable shift even when a sufficient clamp pressure is not secured due to a hydraulic response limit.

  Hereinafter, the best mode for carrying out the present invention will be described based on Example 1 shown in the drawings.

[System configuration of vehicle equipped with double piston type CVT hydraulic control device]
FIG. 1 is a system configuration diagram of a vehicle equipped with a double piston type CVT hydraulic control device. The power of the engine 10 is transmitted to the CVT 300 via the torque converter 20 and the forward / reverse clutch 30. The CVT 300 includes a primary pulley 310 on the driving side and a secondary pulley 320 on the driven side, and transmits power by a belt 90 interposed therebetween.

  The primary pulley 310 has a primary piston chamber 312 that generates thrust for shifting and a primary clamp chamber 313 that generates thrust for preventing belt slip, and the secondary pulley 320 similarly has a secondary piston chamber 322 and a secondary clamp chamber 323.

  The thrust in each of the pulleys 310 and 320 is a resultant force of the thrust based on the hydraulic pressure in the piston chambers 312 and 322 and the thrust based on the hydraulic pressure in the clamp chambers 313 and 323, and the resultant force of the thrust on the primary side and the secondary side is the primary slide pulley 311 and By acting on the secondary slide pulley 321, the slide pulleys 311 and 321 slide to achieve speed change.

  The piston chambers 312 and 322 are respectively connected to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72, and the clamp chambers 313 and 323 are connected to each other and to the select high valve 80. The select high valve 80 is connected to the primary and secondary pressure regulating valves 71 and 72, selects the high hydraulic pressure side, and introduces pressure into the primary and secondary clamp chambers 313 and 323. Selection is performed mechanically without electrical control, and the higher pressure selected here becomes the clamp pressure. In addition, it is good also as selecting the high voltage | pressure side electrically using a solenoid etc., It does not specifically limit.

  In the present embodiment, since the high pressure side of the hydraulic pressure of the primary piston chamber 312 and the secondary piston chamber 322 is introduced into the clamp chambers 313 and 323, the actual clamp pressure is the primary, the primary provided in the secondary piston chambers 312 and 322, Of the detection values of the secondary pressure sensors 314 and 324, the high pressure side is used. The actual clamp pressure Pcl may be detected by providing a pressure sensor in each of the clamp chambers 313 and 323, and is not particularly limited.

  The oil pump 40 supplies oil to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72 via the first pressure regulating valve 51 and supplies oil to the primary solenoid 61 and the secondary solenoid 62 via the second pressure regulating valve 52. It is. Further, the primary solenoid 61 and the secondary solenoid 62 are solenoid valves controlled by the CVT control unit 100, and are controlled by being connected to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72, respectively, and sending a signal pressure.

(Hydraulic control of CVT pulley)
The hydraulic pressure generated by the oil pump 40 is regulated to the line pressure by the first pressure regulating valve 51 and supplied to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72. Further, the pilot pressure is set by the second pressure regulating valve 52 and supplied to the primary solenoid 61 and the secondary solenoid 62. The CVT control unit 100 controls the primary solenoid 61 and the secondary solenoid 62, regulates the supplied pilot pressure to a desired signal pressure, and supplies it to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72.

  The primary pressure regulating valve 71 and the secondary pressure regulating valve 72 regulate the line pressure based on the supplied signal pressure, and supply the hydraulic pressure to the primary piston chamber 312 and the secondary piston chamber 322, respectively. Further, the hydraulic oil regulated by the primary pressure regulating valve 71 and the secondary pressure regulating valve 72 is also introduced into the select high valve 80, and the higher hydraulic pressure is selected and introduced into the primary and secondary clamp chambers 313 and 323.

If the pressure receiving areas of the piston chambers 312 and 322 and the clamp chambers 313 and 323 are Ap, As and Acl, the hydraulic pressure in each of the piston chambers 312 and 32 is Pp and Ps, and the clamp pressure is Pcl, the primary slide pulley 311 and the secondary slide The thrust Fp, Fs applied to the pulley 323 is
Fp = Ap ・ Pp + Acl ・ Pcl ... (1)
Fs = As ・ Ps + Acl ・ Pcl ... (2)
It becomes.

Here, for example, when the working hydraulic pressure on the secondary side is high, the secondary high pressure Ps is introduced into the primary and secondary clamp chambers 313 and 323 by the select high valve 80, and Pcl = Ps. Therefore, the thrust of each pulley 310, 320 is
Fp = Ap ・ Pp + Acl ・ Ps ・ ・ ・ (3)
Fs = As ・ Ps + Acl ・ Ps ... (4)
Thus, the slide pulleys 311 and 321 are slid on the basis of the thrusts Fp and Fs to achieve speed change.

At this time, the target oil pressure
P * s = P * cl
It becomes. When the working hydraulic pressure on the primary side is high, the clamp pressure Pcl = Pp. At this time, the target oil pressure
P * p = P * cl
It becomes.

[Belt slip avoidance control]
FIG. 2 is a graph showing temporal changes in pulley pressure and thrust of a double piston CVT during normal gear shifting, and FIG. 3 is a case where the actual secondary pressure Ps is lower than the secondary target hydraulic pressure P * s due to problems such as hydraulic response. It is a figure which shows a time-dependent change. Here, it is assumed that the secondary pulley pressure Ps is higher than the primary pulley pressure Pp, and the actual secondary pressure Ps is used as the actual clamp pressure.

  At this time, if the secondary target oil pressure P * s does not increase sufficiently due to the oil pressure response limit as shown in FIG. 3, the clamp pressure Pcl will similarly fall below the target value. Therefore, the thrust due to the clamping pressure of the primary pulley 310 is reduced, the thrust of the primary pulley 310 falls below the belt slip limit, and belt slip may occur in the primary slide pulley 311.

  FIG. 4 is a diagram showing temporal changes in pulley pressures and thrusts that have been subjected to hydraulic pressure correction to avoid belt slip. In order to avoid belt slip as described above, in the hydraulic control device of the belt type continuously variable transmission of the present application, the actual hydraulic pressure Ps on the secondary side does not sufficiently respond to the target hydraulic pressure P * s due to problems such as hydraulic response. If not reached, the target clamp pressure P * cl is compared with the actual clamp pressure Pcl. If this actual clamp pressure Pcl is lower than the target clamp pressure P * cl, the target clamp pressure P * cl and the actual clamp pressure Pcl are The difference ΔPcl = P * cl−Pcl is calculated.

  A difference equivalent thrust ΔF = AclΔP corresponding to the difference ΔPcl = is obtained. At this time, since the actual secondary pressure Ps, which is the high-pressure side actual pulley pressure, is introduced as the actual clamp pressure, Pcl = Ps. The hydraulic pressure ΔPp corresponding to the differential equivalent thrust ΔF is added to at least the low-pressure side target hydraulic pressure to calculate the primary-side corrected hydraulic pressure Ppmin. From the relationship of the pressure receiving area, ΔPp = Acl / Ap (P * s−Ps). This primary-side corrected hydraulic pressure Ppmin is set as a primary-side final target hydraulic pressure Ppt. For the secondary side, the secondary target hydraulic pressure P * s is output as it is as the secondary final target hydraulic pressure Pst.

  The above is the control for the case where the actual secondary pressure Ps is higher than the actual primary pressure Pp and the secondary target oil pressure P * s is the target clamp pressure P * cl, but conversely the actual primary pressure Pp is higher and the primary The same applies to the control when the target hydraulic pressure P * p is set to the target clamp pressure P * cl.

[Hydraulic hunting avoidance]
FIG. 5 is a diagram showing temporal changes of the pulley thrusts Fp and Fs when the secondary target hydraulic pressure P * s does not increase due to a physical limit. Although FIG. 5 shows the case where the secondary side is high voltage, the same applies to the case where the primary side is high voltage, so only the case of the secondary side high voltage will be described.

  If there is a physical limit such as a hydraulic response limit, even if the secondary target hydraulic pressure P * s is set high, the pressure does not increase beyond the limit value, and the control error with the target hydraulic pressure P * s becomes uselessly large. . At this time, if feedback control of the secondary target oil pressure P * s is performed by PI control or the like, the integral value accumulates with an increase in control error between the actual oil pressure Ps and the target oil pressure P * s, which may cause control hunting. .

  In the embodiment of the present application, as shown in FIG. 5, even if the actual hydraulic pressure Ps on the secondary side does not reach the target hydraulic pressure P * s, the secondary target hydraulic pressure P * s is not changed and is controlled as the final target hydraulic pressure Pst. To do. Therefore, the secondary target hydraulic pressure P * s on the high pressure side is not increased unnecessarily, and control hunting associated with an increase in the control error of the secondary target hydraulic pressure P * s is avoided.

  Hereinafter, a control configuration and control processing for performing the above-described belt slip avoidance control will be described.

[Control block diagram of CVT control unit]
FIG. 6 is a control block diagram of the CVT control unit 100. The CVT control unit 100 includes a target thrust calculation unit 110, a thrust correction unit 120, a hydraulic pressure conversion unit 130, a final hydraulic pressure determination ECU 140, and a hydraulic pressure command unit 150.

  In addition, a vehicle equipped with a hydraulic control device for a belt type continuously variable transmission of the present application is provided with a rotation speed sensor that detects the rotation speeds Np and Ns of the primary pulley 310 and the secondary pulley 320. Further, a throttle opening sensor, an engine speed sensor, a vehicle speed sensor, and the like are provided, and the detected value is output to the CVT control unit 100.

  The target thrust calculation unit 110 is configured to detect the target thrust of the pulleys 310 and 320 corresponding to the target gear ratio based on the detected primary and secondary rotational speeds Np and Ns, the throttle opening TVO, the engine rotational speed Ne, the vehicle speed VSP, and the like. F * p and F * s are calculated and output to the thrust correction unit 120.

  The thrust correcting unit 120 calculates the centrifugal hydraulic pressure based on the primary and secondary rotational speeds Np and Ns, and based on the centrifugal hydraulic pressure and the elastic force of the springs provided on the slide pulleys 311 and 321, the inputted target thrust F * p and F * s are corrected, and correction values Fpt and Fst are output to the hydraulic pressure conversion unit 130.

  Based on the input target thrust correction values Fpt and Fst, the hydraulic pressure conversion unit 130 converts the target hydraulic pressures P * p and P * s in the piston chambers 311 and 321 of the primary and secondary pulleys 310 and 320 to determine the final hydraulic pressure. Output to ECU 140.

  The final hydraulic pressure determination ECU 140 corrects the input target hydraulic pressures P * p and P * s so as not to fall below the belt slip lower limit value based on the actual pulley pressures Pp and Ps in the primary piston chamber 312 and the secondary piston chamber 322. The final target hydraulic pressures Ppt and Pst are output to the hydraulic pressure command unit 150.

  The hydraulic pressure command unit 150 feedback-controls the input final target hydraulic pressures Ppt and Pst based on the actual pulley pressures Pp and Ps, converts them into control currents i * p and i * s for the solenoids 61 and 62, and outputs them. .

[Control block diagram of final hydraulic pressure decision ECU]
FIG. 7 is a control block diagram in final hydraulic pressure determination ECU 140. The final hydraulic pressure determination ECU 140 includes an actual clamp pressure estimation unit 141, a corrected hydraulic pressure calculation unit 142, a low pressure selection unit 143, and a final target hydraulic pressure determination unit 144.

  The actual clamp pressure estimation unit 141 estimates the actual clamp pressure Pcl based on the actual pulley pressures Pp and Ps in the primary piston chamber 312 and the secondary piston chamber 322, and outputs them to the corrected hydraulic pressure calculation unit 142. In the CVT hydraulic control device of the present application, the higher one of the actual pulley pressures Pp and Ps is actually clamped in order to introduce the primary and secondary pulley pressures Pp and Ps into the respective clamp chambers 313 and 323 as the clamping pressure. Estimated as pressure Pcl.

  The corrected hydraulic pressure calculation unit 142 calculates corrected hydraulic pressures Ppmin and Psmin that are lower hydraulic pressures necessary to achieve the target thrust based on the input parameters P * p, P * s, P * cl, and Pcl. Output to the low-pressure selector 143.

  The low pressure selector 143 compares the input correction hydraulic pressures Ppmin and Psmin, and selects the low pressure side hydraulic pressure, that is, min (Ppmin, Psmin). When Ppmin is selected, the value of Ppmin is output to the final target hydraulic pressure determination unit 144. When Psmin is selected, the value of Psmin is output to the final target hydraulic pressure determination unit 144.

[CVT hydraulic control process]
FIG. 8 is a flowchart showing the flow of pulley thrust calculation control processing executed in the CVT control unit 100. Hereinafter, each step S will be described.

  In step S101, the target thrust calculation unit 110 calculates the target thrust F * p in the primary piston chamber 312 and the secondary piston chamber 322 from the primary rotational speed Np, secondary rotational speed Ns, engine rotational speed Ne, throttle opening TVO, vehicle speed VSP, and the like. F * s is calculated, and the process proceeds to step S102.

  In step S102, based on the actual pulley pressures Pp and Ps of the primary and secondary piston chambers 312 and 322 and the spring force and centrifugal oil pressure that hold the slide pulleys 311 and 321, the thrust correction unit 120 uses the target thrusts F * p and F *. s is corrected, target thrust correction values Fpt and Fst are calculated, and the process proceeds to step S103.

  In step S103, the target hydraulic pressures P * p and P * s and the target clamp pressure P * cl corresponding to the target thrust correction values Fpt and Fst input in the hydraulic pressure conversion unit 130 are calculated, and the process proceeds to step S104.

  In step S104, final target oil pressures Ppt and Pst are calculated in the final oil pressure determination ECU 140 so as to avoid belt slip, and the process proceeds to step S105.

In step S105, the hydraulic pressure command unit 150 performs feedback control on the input final target hydraulic pressures Ppt and Pst, converts them into control currents ip _FB and is _FB for the solenoids 61 and 62, and ends the control. .

[Final oil pressure determination (belt slip avoidance) control processing]
FIG. 9 is a flowchart showing a flow of control processing in step S104 in the flowchart of FIG. 8, that is, a flow of hydraulic pressure conversion control processing executed by the final hydraulic pressure determination ECU 140. Hereinafter, each step S will be described.

  In step S201, actual pulley pressures Pp and Ps are read by the actual clamp pressure estimation unit 141, and the process proceeds to step S202.

  In step S202, the clamp pressure determination unit 142 determines whether the actual primary pressure Pp is greater than the actual secondary pressure Ps. If YES, the process proceeds to step S203, and if NO, the process proceeds to step S204.

  In step S203, Pcl = Pp is set, and the process proceeds to step S205.

  In step S204, Pcl = Ps is set, and the process proceeds to step S206.

  In step S205, it is determined whether P * cl is equal to or less than Pp. If YES, the process proceeds to step S209, and if NO, the process proceeds to step S207.

  In step S206, it is determined whether P * cl is equal to or less than Pp. If YES, the process proceeds to step S212, and if NO, the process proceeds to step S208.

  In step S207, Psmin is calculated, and the process proceeds to step S210.

  In step S208, Ppmin is calculated, and the process proceeds to step S211.

  In step S209, the final target oil pressures Ppt and Pst are output as the target oil pressures P * p and P * s, and the process proceeds to step S105 in FIG.

  In step S210, the final target hydraulic pressures Ppt and Pst are output as corrected hydraulic pressures P * p and Psmin, and the process proceeds to step S105 in FIG.

  In step S211, the final target hydraulic pressures Ppt and Pst are output as corrected hydraulic pressures Ppmin and P * s, and the process proceeds to step S105 in FIG.

  In step S212, the final target oil pressures Ppt and Pst are output as the target oil pressures P * p and P * s, and the process proceeds to step S105 in FIG.

[Contrast between the effects of the prior art and the embodiment of the present application]
Conventionally, in the double piston type CVT, a thrust generating chamber (piston chamber) for shifting and a thrust generating chamber (clamp chamber) for preventing belt slip are provided on the primary side and the secondary side, respectively, to avoid belt slip at the time of shifting. (For example, see Patent Document 1)

  However, in the above prior art, since the primary and secondary clamp chambers communicate with each other, the same clamping pressure always acts on each pulley. Therefore, when the higher hydraulic pressure of the pulley pressures on the primary side and the secondary side is used as the clamp pressure, it is necessary to lower the lower piston chamber hydraulic pressure in order to secure the differential thrust in the shift. At this time, if the higher hydraulic pressure is not sufficiently ensured due to the problem of the hydraulic response limit, the lower piston chamber hydraulic pressure falls below the slip limit, which may cause belt slip. It was.

  On the other hand, in the embodiment of the present invention, the actual hydraulic pressure on the secondary side is higher than the primary, and the actual secondary pressure Ps is used as the actual clamp pressure Pcl, and the actual hydraulic pressure Ps on the secondary side does not respond sufficiently and the target hydraulic pressure P If * s is not reached, the target clamp pressure P * cl is compared with the actual clamp pressure Pcl. If this actual clamp pressure Pcl is lower than the target clamp pressure P * cl, the target clamp pressure P * cl and the actual clamp pressure are compared. Difference ΔPcl = P * cl-Pcl from Pcl is calculated. A difference equivalent thrust ΔF = AclΔP corresponding to the difference ΔPcl is obtained. Since Pcl = Ps at this time, the hydraulic pressure ΔPp = Acl / Ap (P * s−Ps) corresponding to this differential equivalent thrust ΔF is added to the primary side to calculate the primary side corrected hydraulic pressure Ppmin, and the final target hydraulic pressure Ppt , Pst is corrected hydraulic pressure Ppmin, P * s.

  On the other hand, when the actual primary pressure Pp is used as the actual clamp pressure Pcl and the actual hydraulic pressure Pp on the primary primary side does not reach the target hydraulic pressure P * p, the target clamp pressure P * cl and the actual The clamp pressure Pcl is compared. If the actual clamp pressure Pcl is lower than the target clamp pressure P * cl, a difference ΔPcl = P * cl−Pcl between the target clamp pressure P * cl and the actual clamp pressure Pcl is calculated. A difference equivalent thrust ΔF = AclΔP corresponding to the difference ΔPcl is obtained. At this time, since Pcl = Pp, the hydraulic pressure ΔPs = Acl / Ap (P * p-Pp) corresponding to this differential equivalent thrust ΔF is added to the secondary side to calculate the secondary side corrected hydraulic pressure Psmin, and the final target hydraulic pressure Ppt , Pst is corrected hydraulic pressure P * p, Psmin.

  As a result, it is possible to provide a hydraulic control device for a belt-type continuously variable transmission that can prevent a belt slip and achieve a stable shift even when a sufficient pulley pressure is not ensured due to a hydraulic response limit. . Further, by correcting the oil pressure command value and calculating the final target oil pressures Ppt and Pst, an existing oil pressure feedback system (in this embodiment, feedback using the actual pulley pressures Pp and Ps in the oil pressure command unit 150 shown in FIG. 6). Control) stability can be maintained.

  In addition, when calculating the correction oil pressures Ppmin and Psmin, the lower one of the primary and secondary correction oil pressures is selected, and control is performed without inadvertently increasing the accumulated error value in the existing oil pressure feedback control. And the stability of the hydraulic feedback can be ensured.

  Also, by setting the higher of the primary and secondary actual hydraulic pressures Pp, Ps to the actual clamp pressure Pcl, it is possible to keep the hydraulic pressure of the entire system low, and to improve fuel efficiency by reducing the load on the oil pump. Can do. Further, by setting the higher one of the primary and secondary actual hydraulic pressures Pp and Ps as the actual clamp pressure Pcl, the pressure sensor for detecting the clamp pressure Pcl can be omitted, and the cost can be reduced.

(Other examples)
As described above, the best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to each embodiment and does not depart from the gist of the present invention. Such design changes are included in the present invention.

1 is a system configuration diagram of a vehicle equipped with a CVT hydraulic control device. It is a figure which shows the time-dependent change of each pulley pressure and thrust of double piston type CVT at the time of normal gear shifting. It is a figure which shows a time-dependent change in case actual secondary pressure is low with respect to secondary target oil_pressure | hydraulic by problems, such as a hydraulic response. It is a figure which shows the time-dependent change of each pulley pressure and thrust which performed oil pressure correction | amendment in order to avoid a belt slip. It is a figure which shows the time-dependent change of each pulley thrust in case the secondary target hydraulic pressure does not increase by a physical limit. It is a control block diagram of a CVT control unit. It is a control block diagram in the final oil pressure determination ECU. It is a flowchart which shows the flow of the pulley thrust calculation control process performed in a CVT control unit. It is a flowchart which shows the flow of the hydraulic pressure conversion control process performed by final hydraulic pressure determination ECU.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 20 Torque converter 30 Forward / reverse clutch 40 Oil pump 51 1st pressure regulation valve 52 2nd pressure regulation valve 61 Primary solenoid 62 Secondary solenoid 71 Primary pressure regulation valve 72 Secondary pressure regulation valve 100 Control unit 110 Target thrust calculation part 120 Thrust correction part 130 Hydraulic pressure Conversion unit 140 Final hydraulic pressure determination ECU
150 Hydraulic command section 160 Shift control section 170 Hydraulic conversion section 180 Current conversion section 310 Primary pulley 311 Primary slide pulley 312 Primary piston chamber 313 Primary clamp chamber 320 Secondary pulley 321 Secondary slide pulley 322 Secondary piston chamber 323 Secondary clamp chamber

Claims (2)

A primary pulley having a primary piston chamber;
A secondary pulley having a secondary piston chamber;
A belt for transmitting power between the primary pulley and the secondary pulley by friction force;
Wherein each is provided on the primary pulley and the secondary pulley, and a primary clamp chamber and a secondary clamp chamber connected by communication paths with each other,
High pressure side selective introduction means for introducing the higher hydraulic pressure of the primary piston chamber and the secondary piston chamber into the communication passage as a clamp pressure;
Oil pressure calculating means for calculating a target primary oil pressure and a target secondary oil pressure based on each target thrust of the primary pulley and the secondary pulley;
Actual hydraulic pressure detecting means for detecting actual hydraulic pressure of the primary piston chamber and the secondary piston chamber;
When the actual hydraulic pressure of the higher high-pressure pulley of the target primary hydraulic pressure and the target secondary hydraulic pressure is lower than the target hydraulic pressure of the high-pressure pulley, the thrust by the target hydraulic pressure of the high-pressure pulley and the actual hydraulic pressure of the high-pressure pulley Hydraulic pressure correction control means for calculating the difference between the thrust and the hydraulic pressure corresponding to the difference to the target hydraulic pressure of the other low-pressure pulley ;
Characterized by comprising a belt type continuously variable transmission. The belt-type continuously variable transmission according to claim 1,
The deviation between the target hydraulic pressure of the high pressure pulley calculated by the hydraulic pressure calculation means and the actual hydraulic pressure of the high pressure pulley, the target hydraulic pressure of the low pressure pulley corrected by the correction control means, and the actual hydraulic pressure of the low pressure pulley. A belt-type continuously variable transmission comprising a hydraulic control means for controlling the primary hydraulic pressure and the secondary hydraulic pressure by feedback control based on the deviation of the above .

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