JP4857005B2 - Control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission mounted on a vehicle.

  A continuously variable transmission (CVT) mounted on a vehicle includes a primary pulley provided on an input shaft and a secondary pulley provided on an output shaft, and a drive belt or the like is wound around these pulleys. The primary pulley and the secondary pulley are each provided with a fixed sheave and a movable sheave facing the sheave, and the gear ratio is controlled steplessly by changing the winding diameter of the drive belt. In such a continuously variable transmission, the wrapping diameter of the drive belt is controlled by one pulley (for example, a primary pulley), while slippage of the drive belt is suppressed by the other pulley (for example, a secondary pulley). ing. When executing gear shift control, after setting the target gear ratio with reference to the characteristic map based on the throttle opening and the vehicle speed, the primary pressure regulated based on this target gear ratio is supplied to the primary pulley. become.

  Further, a primary pressure control valve is provided between the oil pump and the primary pulley in order to adjust the hydraulic oil to the primary pressure (see, for example, Patent Document 1). This primary pressure control valve is a pilot operated valve. According to the pilot pressure, the supply state of supplying hydraulic oil to the primary pulley, the discharge state of discharging the hydraulic oil from the primary pulley, the primary pulley It can be switched to a neutral state that holds hydraulic fluid. That is, it is possible to regulate the primary pressure by controlling the operating state of the primary pressure control valve by controlling the energization amount to the electromagnetic pilot valve to regulate the pilot pressure.

  By the way, the relationship between the energization amount for the electromagnetic pilot valve and the operating state of the primary pressure control valve controlled in accordance with the energization amount changes depending on component accuracy, secular change, operating environment, and the like. That is, even when the electromagnetic pilot valve is controlled with the same energization amount, the primary pressure to be regulated varies. Therefore, the control device for the continuously variable transmission described in Patent Document 1 estimates the operating state of the primary pressure control valve based on the primary pressure estimated from the gear ratio and the line pressure, and then the estimated operating state. And learning the relationship between the energization amount of the electromagnetic pilot valve.

  Further, in the control device for a continuously variable transmission described in Patent Document 1, the primary pressure is regulated by one primary pressure control valve. However, the primary pressure is not limited to this, and the primary pulley Control of a continuously variable transmission in which an upshift valve and a downshift valve are connected to each other and the hydraulic oil supply state is controlled by the upshift valve while the hydraulic oil discharge state is controlled by the downshift valve Devices have also been proposed.

Thus, in a control device including an upshift valve and a downshift valve, it is particularly important to learn the relationship between the energization amount for the shift valve and the operating state of the shift valve. That is, in a continuously variable transmission having an upshift valve and a downshift valve, it is necessary to control the upshift valve and the downshift valve at the boundary between the communication state and the cutoff state in order to improve the response of the shift control. However, if the upshift valve or downshift valve is shifted to the shut-off side, the supply and discharge of hydraulic oil will be delayed, and the response of the shift control will be reduced. If it shifts to the communication side, the hydraulic oil discharged from the oil pump is discharged wastefully. In order to avoid such a situation, it is extremely important to learn the relationship between the energization amount for the upshift valve and the downshift valve and the corresponding operating state.
Japanese Patent No. 3141193

  However, the learning method described in Patent Document 1 is applied when controlling the supply and discharge of hydraulic oil with one primary pressure control valve, and this learning method is used as an upshift valve and a downshift. It is difficult to apply to a control device including a valve. Moreover, in the control apparatus described in Patent Document 1, after estimating the primary pressure from the transmission ratio and the line pressure, the operating state of the primary pressure control valve is estimated from the estimated primary pressure and line pressure. It is. That is, since the relationship between the energization amount and the operating state is learned including the estimation error, it is difficult to adjust the primary pressure with high accuracy.

  An object of the present invention is to improve the responsiveness of the shift control while suppressing unnecessary supply and discharge of hydraulic oil by improving the control accuracy of the upshift valve and the downshift valve.

  A control device for a continuously variable transmission according to the present invention includes a speed change pulley and a tightening pulley around which a power transmission element is wound, and controls the winding diameter of the power transmission element using the speed change pulley. A control device for a continuously variable transmission that controls the tension of the power transmission element using a communication state provided between a hydraulic pressure supply source and the transmission pulley, and supplying hydraulic oil to the transmission pulley; A first shift valve that is switched to a shut-off state that stops supply; a communication state that is provided between the transmission pulley and the oil pan and that discharges hydraulic oil from the shift pulley; and a shut-off state that stops discharging. The second shift valve to be switched, and the operation state of the other shift valve is switched from the shut-off state to the communication state while maintaining the operation state of one of the first and second shift valves, A valve driving means for changing the hydraulic oil state in the speed pulley, and a switching operation of the other shift valve based on the change in the hydraulic oil state, and switching the other shift valve from the shut-off state to the communication state And learning control means for learning the driving signal.

  The control device for a continuously variable transmission according to the present invention is characterized in that the learning control means determines a switching operation of the other shift valve based on a change in a gear ratio or a hydraulic pressure.

  The control device for a continuously variable transmission according to the present invention is characterized in that the valve driving means switches the other shift valve from the shut-off state to the communication state while holding the one shift valve in the shut-off state.

  The control device for a continuously variable transmission according to the present invention is characterized in that the valve driving means switches the other shift valve from a shut-off state to a communication state while holding the one shift valve in a communication state.

  The control device for a continuously variable transmission according to the present invention is characterized in that the learning control means learns a drive signal for each predetermined vehicle state.

  According to the present invention, while the operating state of one shift valve is maintained, the operating state of the other shift valve is switched from the shut-off state to the communication state, and the hydraulic oil state in the speed change pulley generated at this time is shifted based on the change. Since the switching operation of the valve is determined and the drive signal for switching the other shift valve from the shut-off state to the communication state is learned, the control accuracy of the shift valve can be improved.

  This makes it possible to control the shift valve at the boundary between the shut-off state and the communication state, so that hydraulic oil can be quickly supplied to the transmission pulley and hydraulic oil can be quickly discharged from the transmission pulley. This makes it possible to improve the responsiveness of the shift control. Moreover, even when the shift valve is controlled at the boundary between the shut-off state and the communication state, unnecessary supply and discharge of hydraulic oil can be avoided, so that unnecessary driving of the hydraulic supply source is avoided and the vehicle is avoided. It becomes possible to improve the fuel efficiency performance.

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

  FIG. 1 is a skeleton diagram showing a continuously variable transmission 10, and this continuously variable transmission 10 is controlled by a control device for a continuously variable transmission according to an embodiment of the present invention. As shown in FIG. 1, the continuously variable transmission 10 includes a primary shaft 12 that is driven by an engine 11 and a secondary shaft 13 that is parallel to the primary shaft 12. A transmission mechanism 14 is provided between the primary shaft 12 and the secondary shaft 13. The rotation of the primary shaft 12 is transmitted to the secondary shaft 13 via the transmission mechanism 14, and the rotation of the secondary shaft 13 is transmitted to the speed reduction mechanism 15 or the like. It is transmitted to the left and right drive wheels 17 via the differential mechanism 16.

  The primary shaft 12 is provided with a primary pulley 20 as a speed change pulley. The primary pulley 20 slides in the axial direction on the primary shaft 12 opposite to the fixed sheave 20a integrated with the primary shaft 12. A movable sheave 20b is provided. Further, the secondary shaft 13 is provided with a secondary pulley 21 as a tightening pulley. The secondary pulley 21 is fixed to the secondary shaft 13 in the axial direction, and a fixed sheave 21a integrated with the secondary shaft 13 is opposed thereto. The movable sheave 21b is slidable. A drive belt 22 as a power transmission element is wound around the primary pulley 20 and the secondary pulley 21, and the winding diameter of the drive belt 22 is stepless by changing the pulley groove width between the primary pulley 20 and the secondary pulley 21. It becomes possible to change to. If the winding diameter of the drive belt 22 around the primary pulley 20 is Rp and the winding diameter around the secondary pulley 21 is Rs, the transmission ratio of the transmission mechanism 14 is Rs / Rp.

  In order to change the pulley groove width of the primary pulley 20, the plunger 23 is fixed to the primary shaft 12, and the movable sheave 20 b is fixed to the cylinder 24 slidably contacting the outer peripheral surface of the plunger 23, A hydraulic oil chamber 25 is defined by the plunger 23 and the cylinder 24. Similarly, in order to change the pulley groove width of the secondary pulley 21, a plunger 26 is fixed to the secondary shaft 13, and a cylinder 27 that slidably contacts the outer peripheral surface of the plunger 26 is fixed to the movable sheave 21b. The hydraulic oil chamber 28 is partitioned by the plunger 26 and the cylinder 27. Each pulley groove width is controlled by adjusting the primary pressure supplied to the primary hydraulic fluid chamber 25 and the secondary pressure supplied to the secondary hydraulic fluid chamber 28.

  A torque converter 30 and a forward / reverse switching mechanism 31 are provided between the crankshaft 11a and the primary shaft 12. The torque converter 30 includes a pump impeller 30a connected to the crankshaft 11a and a turbine runner 30b facing the pump impeller 30a. A turbine shaft 32 is connected to the turbine runner 30b. Furthermore, a lock-up clutch 33 for fastening the crankshaft 11a and the turbine shaft 32 is incorporated in the torque converter 30 according to the running state. On the other hand, the forward / reverse switching mechanism 31 includes a double-pinion planetary gear train 34, a forward clutch 35, and a reverse brake 36. The forward clutch 35 and the reverse brake 36 are operated to transmit an engine power transmission path. Is switched. When both the forward clutch 35 and the reverse brake 36 are released, the turbine shaft 32 and the primary shaft 12 are disconnected, and the forward / reverse switching mechanism 31 is switched to a neutral state in which power is not transmitted to the primary shaft 12. When the reverse brake 36 is released and the forward clutch 35 is engaged, the rotation of the turbine shaft 32 is transmitted to the primary pulley 20 as it is, and when the forward clutch 35 is released and the reverse brake 36 is engaged, The rotated rotation of the turbine shaft 32 is transmitted to the primary pulley 20.

  The secondary shaft 13 is provided with a fuse clutch 37. The fuse clutch 37 is a friction clutch whose torque capacity changes according to the clutch pressure. Further, the torque capacity of the fuse clutch 37 is controlled to be slightly smaller than the torque capacity of the transmission mechanism 14, and even when excessive input torque, braking torque, or the like is input to the continuously variable transmission 10, By first sliding the fuse clutch 37, transmission of input torque and the like can be limited, and the transmission mechanism 14 can be protected by suppressing the slippage of the drive belt 22. That is, the fuse clutch 37 functions as a torque limiter for the transmission mechanism 14.

  FIG. 2 is a schematic diagram showing a hydraulic control system and an electronic control system of the continuously variable transmission 10. As shown in FIG. 2, in order to supply hydraulic oil to the primary pulley 20 and the secondary pulley 21, the continuously variable transmission 10 is provided with an oil pump 40 as a hydraulic supply source driven by the engine 11. . A line pressure control valve 42 is connected to the line pressure path 41 connected to the discharge port of the oil pump 40, and the line pressure control valve 42 regulates the line pressure PL that is the basic hydraulic pressure of the hydraulic control circuit. . Further, the line pressure path 41 is branched, and the secondary pressure control valve 43 is connected to one line pressure path 41 a extending toward the secondary pulley 21, and the other line pressure extending toward the primary pulley 20. An upshift valve (first shift valve) 44 that supplies hydraulic oil to the primary pulley 20 is connected to the path 41b. Further, a branch oil passage 46 is provided in the primary pressure passage 45 extending from the upshift valve 44 toward the hydraulic oil chamber 25, and an oil pan 48 is provided in the branch oil passage 46 via a discharge oil passage 47 from the primary pulley 20. A downshift valve (second shift valve) 49 for discharging the hydraulic oil is connected to the main body. The secondary pressure control valve 43 connected to the secondary pulley 21 via the secondary pressure path 50 is controlled based on a target gear ratio and input torque described later, and regulates the secondary pressure Ps to drive belt. The tension of 22 can be controlled. Further, the upshift valve 44 and the downshift valve 49 connected to the primary pulley 20 are controlled based on the target gear ratio, and the primary pressure Pp is adjusted to reduce the winding diameter of the drive belt 22. It is possible to control.

  The line pressure control valve 42, the secondary pressure control valve 43, the upshift valve 44, and the downshift valve 49 are pilot operation valves whose operating states are switched by a pilot fluid. The line pressure control valve 42 is supplied with the pilot pressure P1 from the pilot valve 51, and the line pressure PL can be adjusted according to the magnitude of the pilot pressure P1. The secondary pressure control valve 43 is supplied with a pilot pressure P2 from the pilot valve 52, and the secondary pressure Ps can be regulated according to the magnitude of the pilot pressure P2. Further, the pilot pressure P3 is supplied from the pilot valve 53 to the upshift valve 44, and the primary pressure Pp can be increased according to the magnitude of the pilot pressure P3, while the pilot signal is supplied to the downshift valve 49. A pilot pressure P4 is supplied from the valve 54, and the primary pressure Pp can be reduced according to the magnitude of the pilot pressure P4.

  The pilot valves 51 to 54 for controlling the line pressure control valve 42, the secondary pressure control valve 43, the upshift valve 44, and the downshift valve 49 control the current values for the solenoids 51a to 54a to control the pilot pressures P1 to P4. It is a linear solenoid valve that regulates pressure. The pilot valves 51 to 54 are not limited to linear solenoid valves, and may be duty solenoid valves that adjust the pilot pressures P1 to P4 by controlling the duty ratio with respect to the solenoids 51a to 54a. .

  A CVT control unit 60 that outputs a drive current (drive signal) toward the pilot valves 51 to 54 and executes the shift control of the continuously variable transmission 10 includes a microprocessor (CPU) (not shown). ROM, RAM and I / O ports are connected to the CPU via a bus line. The ROM stores a control program, various map data, and the like, and the RAM temporarily stores data processed by the CPU. Also, detection signals indicating the running state of the vehicle are input from various sensors to the CPU via the I / O port.

  Various sensors for inputting a detection signal to the CVT control unit 60 include a primary rotational speed sensor 61 that detects the rotational speed of the primary pulley 20, a secondary rotational speed sensor 62 that detects the rotational speed of the secondary pulley 21, and a shift range. There are an inhibitor switch 63, a hydraulic oil temperature sensor 64 that detects the temperature of the hydraulic oil, an accelerator pedal sensor 65 that detects the amount of depression of the accelerator pedal, a vehicle speed sensor 66 that detects the vehicle speed, and the like. An engine control unit 67 is connected to the CVT control unit 60, and engine information such as the throttle opening and the engine speed is input from the engine control unit 67.

  Subsequently, a calculation procedure of the target primary pressure Pp and the target secondary pressure Ps by the CVT control unit 60 will be described. FIG. 3 is a block diagram showing a shift control system of the CVT control unit 60. As shown in FIG. 3, in order to set the target primary pressure Pp, the target primary rotation speed calculation unit 70 calculates the target primary rotation speed Np by referring to a predetermined shift map based on the vehicle speed V and the throttle opening degree To. The target gear ratio calculation unit 71 calculates the target gear ratio i based on the target primary rotation speed Np and the actual secondary rotation speed Ns ′. Next, the hydraulic ratio calculation unit 72 calculates a hydraulic ratio (Pp / Ps) between the target primary pressure Pp and the target secondary pressure Ps corresponding to the target speed ratio i, and the target primary pressure calculation unit 73 calculates the hydraulic ratio. A target primary pressure Pp is calculated by multiplying a target secondary pressure Ps described later. Further, the actual speed ratio calculating unit 74 calculates the actual speed ratio i ′ based on the actual primary speed Np ′ and the actual secondary speed Ns ′, and the feedback value calculating part 75 calculates the actual speed ratio i ′ and the target speed ratio. A feedback value f is calculated based on the ratio i. The CVT control unit 60 sets the drive current based on the target primary pressure Pp subjected to feedback control, and then outputs this drive current to the pilot valves 52 to 54 so that the primary pulley 20 is directed to the target gear ratio i. Control.

  In addition, in order to calculate the target secondary pressure Ps, the input torque calculation unit 76 calculates the engine torque based on the engine speed Ne and the throttle opening degree To, and then adds the amplified torque of the torque converter 30 to the engine torque. An input torque Ti input to the primary pulley 20 is calculated. Then, the necessary secondary pressure calculation unit 77 refers to a predetermined characteristic map based on the target gear ratio i, and calculates the necessary secondary pressure Psn per unit torque. Then, the target secondary pressure calculation unit 78 calculates the target secondary pressure Ps supplied to the secondary pulley 21 by multiplying the required secondary pressure Psn per unit torque by the input torque Ti. Subsequently, after setting the drive current based on the target secondary pressure Ps, the CVT control unit 60 can output the drive current to the pilot valves 51 and 52 to cause the secondary pulley 21 to be tightened. It becomes possible to suppress the slip of the drive belt 22.

  Hereinafter, a method for regulating the primary pressure Pp by the upshift valve 44 and the downshift valve 49 will be described. 4 (A) to 4 (C) are explanatory views showing the process of switching the upshift valve 44 from the shut-off state to the communication state, and FIGS. 5 (A) to 5 (C) show the downshift valve 49 from the shut-off state. It is explanatory drawing which shows the process at the time of switching to a communication state. The same members as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 4A to 4C, the upshift valve 44 includes a housing 80 in which a valve accommodating hole is formed, and a spool valve shaft 81 that is movably accommodated in the valve accommodating hole. . The housing 80 is formed with an input port 80a that communicates with the line pressure path 41b and an output port 80b that communicates with the primary pressure path 45. The spool valve shaft 81 accommodated in the housing 80 has an input port 80a. 4A, which shuts off the output port 80b, and the communication position shown in FIG. 4C, which connects the input port 80a and the output port 80b. A pilot pressure chamber 80c to which a pilot pressure P3 is supplied is defined on one end side of the spool valve shaft 81, and a spring chamber 80d in which a spring member 82 is incorporated is defined on the other end side of the spool valve shaft 81. . As shown in FIG. 4A, the spool valve shaft 81 urged by the spring member 82 moves in the direction of the arrow a toward the shut-off position by lowering the pilot pressure P3 by lowering the drive current to the solenoid 53a. On the other hand, as shown in FIGS. 4B and 4C, the spool valve shaft 81 moves toward the communicating position while compressing the spring member 82 by increasing the pilot current P3 by increasing the drive current to the solenoid 53a. It moves in the b direction. FIG. 4B shows the spool valve shaft 81 moved to the boundary position. By moving the spool valve shaft 81 in the direction of arrow a from this boundary position, the operating state of the upshift valve 44 is switched to a shut-off state in which the supply of hydraulic oil to the primary pulley 20 is stopped, while the spool valve shaft is switched from the boundary position. By moving 81 in the direction of arrow b, the operating state of the upshift valve 44 is switched to a communicating state in which operating oil is supplied to the primary pulley 20.

  Subsequently, as shown in FIGS. 5A to 5C, the downshift valve 49 includes a housing 85 in which a valve accommodating hole is formed, and a spool valve shaft 86 that is movably accommodated in the valve accommodating hole. I have. The housing 85 is formed with an input port 85a connected to the branch oil passage 46 and a discharge port 85b connected to the discharge oil passage 47. The spool valve shaft 86 accommodated in the housing 85 has an input It is freely movable between the blocking position of FIG. 5A where the port 85a and the discharge port 85b are blocked and the communication position of FIG. 5C where the input port 85a and the discharge port 85b are connected. A pilot pressure chamber 85c to which a pilot pressure P4 is supplied is defined on one end side of the spool valve shaft 86, and a spring chamber 85d in which a spring member 87 is incorporated is defined on the other end side of the spool valve shaft 86. . As shown in FIG. 5A, the spool valve shaft 86 biased by the spring member 87 moves in the direction of the arrow a toward the shut-off position by lowering the pilot pressure P4 by lowering the drive current to the solenoid 54a. On the other hand, as shown in FIGS. 5B and 5C, the spool valve shaft 86 moves toward the communicating position while compressing the spring member 87 by increasing the pilot current P4 by increasing the drive current to the solenoid 54a. It moves in the b direction. FIG. 5B shows the spool valve shaft 86 moved to the boundary position. By moving the spool valve shaft 86 in the direction of the arrow a from this boundary position, the operating state of the downshift valve 49 is switched to a shut-off state in which the discharge of hydraulic oil from the primary pulley 20 is stopped. By moving 81 in the direction of arrow b, the operating state of the upshift valve 44 is switched to a communication state in which hydraulic oil is discharged from the primary pulley 20.

  Subsequently, learning control for learning the drive current when the upshift valve 44 and the downshift valve 49 are switched from the shut-off state to the communication state, that is, the drive current necessary for moving the spool valve shafts 81 and 86 to the boundary position. explain. FIG. 6 is a flowchart showing a procedure when the learning control is executed, and FIGS. 7A and 7B are explanatory diagrams showing a change state of the gear ratio accompanying the learning control. This learning control is executed based on a control signal from the CVT control unit 60 that functions as a valve driving means and a learning control means.

  As shown in FIG. 6, in step S1, it is determined whether a learning condition is satisfied. If it is determined in step S1 that the select range is the neutral range (N range) and the temperature of the hydraulic oil exceeds a predetermined value, the process proceeds to the subsequent step S2, where the upshift valve 44 and the downshift valve 49 are Switch to the shut-off state. Thus, when the learning condition is satisfied, both shift valves 44 and 49 are switched to the shut-off state, and the speed ratio of the speed change mechanism 14 is kept constant (reference a in FIG. 7A). Although the learning control is executed when the vehicle is stopped, the drive wheel 17 and the transmission mechanism 14 are disconnected by releasing the fuse clutch 37 when the N range is selected, so that the primary pulley 20 and the secondary pulley 21 rotate slowly. The state is maintained, and the gear ratio changes according to the increase or decrease of the primary pressure Pp.

  Subsequently, in step S3, the spool valve shaft 81 of the upshift valve 44 is gradually moved toward the communication position by gradually increasing the drive current for the pilot valve 53 (sweep operation). In this way, by gradually increasing the pilot pressure P3 and moving the spool valve shaft 81, when the spool valve shaft 81 moves in the direction of the arrow b past the boundary position shown in FIG. Supply of hydraulic oil is started via 80a (reference symbol b in FIG. 7A). The pulley groove width of the primary pulley 20 is narrowed by the hydraulic oil supplied through the upshift valve 44, and the gear ratio is controlled to the overdrive side.

  Next, in step S4, it is determined whether or not the speed ratio change amount exceeds a predetermined value α. When the gear ratio change amount is less than the predetermined value α, the sweep operation of the spool valve shaft 81 is continued, whereas when the gear ratio change amount is more than the predetermined value α (see symbol c in FIG. 7A), In step S5, the current value of the drive current supplied to the solenoid 53a of the pilot valve 53 is read. Since the current value read in step S5 is the current value when the spool valve shaft 81 moves past the boundary position, the current value when the spool valve shaft 81 is operated to the boundary position in the subsequent step S6. The read current value is corrected after being corrected based on test data or the like so that the current value is obtained. Note that the gear ratio is calculated based on the primary rotational speed and the secondary rotational speed.

  In step S7, it is determined whether or not to continue the learning control. When it is determined that the learning is to be continued, that is, when the learning control of the downshift valve 49 is executed, the learning control is started again from step S2. In step S2, both shift valves 44 and 49 are switched to the shut-off state, and the speed ratio of the speed change mechanism 14 is kept constant (reference a in FIG. 7B). In the subsequent step S3, the spool valve shaft 86 of the downshift valve 49 starts the sweep operation toward the communication position by gradually increasing the drive current of the pilot valve 54. Then, when the spool valve shaft 86 moves past the boundary position shown in FIG. 5B in the direction of the arrow b, the discharge of the hydraulic oil is started through the open discharge port 85b (see FIG. 7B). b) The pulley groove width of the primary pulley 20 is widened, and the gear ratio is controlled to the low side. In subsequent step S4, it is determined whether or not the speed ratio change amount exceeds a predetermined value α. When the gear ratio change amount is less than the predetermined value α, the sweep operation of the spool valve shaft 86 is continued, while when the gear ratio change amount exceeds the predetermined value α (see symbol c in FIG. 7B), In step S5, the current value of the drive current for the solenoid 54a is read, and in the subsequent step S6, the current value is corrected and recorded.

  In this way, the spool valve shafts 81 and 86 of the upshift valve 44 and the downshift valve 49 are swept, and the switching operation of the upshift valve 44 and the downshift valve 49 is performed based on the amount of change in the gear ratio accompanying the sweep operation. Since the driving current necessary for controlling the spool valve shafts 81 and 86 to the boundary position is learned, the spool valve shafts 81 and 86 are not affected by individual variations or aging. It is possible to accurately hold the boundary position. Thereby, since supply and discharge | emission of hydraulic fluid can be started quickly, it becomes possible to improve the responsiveness of transmission control. In addition, since the spool valve shafts 81 and 86 are accurately controlled to the boundary positions, unnecessary supply and discharge of hydraulic oil can be avoided, so that unnecessary oil pump drive is avoided and the fuel consumption of the engine 11 is reduced. Can be suppressed.

  FIG. 8 is a flowchart showing a learning control procedure executed by the control apparatus according to another embodiment of the present invention. FIGS. 9A and 9B show the change ratio of the gear ratio associated with the learning control. It is explanatory drawing shown. In the flowchart of FIG. 8, the same steps as those shown in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 8, when the learning condition is satisfied in step S1, the upshift valve 44 is switched to a shut-off state in step S11, and the downshift valve 49 is switched to a predetermined communication state in step S12. Here, the predetermined communication state is a state in which the spool valve shaft 86 has moved to the communication side past the boundary position, and the gear ratio changes by a predetermined gear ratio by holding the downshift valve 49 in the predetermined communication state. It is controlled to the low side at a rate (shift speed) (reference a in FIG. 9A). In step S3, the spool valve shaft 81 of the upshift valve 44 starts the sweep operation toward the communication position. When the spool valve shaft 81 moves past the boundary position shown in FIG. 4B in the direction of the arrow b, the supply of hydraulic oil is started via the input port 80a that opens (reference numeral b in FIG. 9A). The transmission speed of the transmission mechanism 14 gradually decreases. In the subsequent step S13, it is determined whether or not the absolute value of the speed change ratio is less than a predetermined value β. In this step S13, when the absolute value of the speed ratio change rate exceeds the predetermined value β, the sweep operation of the spool valve shaft 81 is continued, whereas when the absolute value of the speed ratio change rate is lower than the predetermined value β ( In FIG. 9A, reference numeral c) proceeds to step S5, and the current value of the driving current supplied to the solenoid 53a of the pilot valve 53 is read. Since the current value read in step S5 is the current value when the spool valve shaft 81 moves past the boundary position, the current value when the spool valve shaft 81 is operated to the boundary position in the subsequent step S6. The read current value is corrected and recorded so as to be the current value.

  Similarly, when the learning control of the downshift valve 49 is executed, the downshift valve 49 is switched to the shut-off state in step S11, and the upshift valve 44 is switched to a predetermined communication state in the subsequent step S12. Here, the predetermined communication state is a state in which the spool valve shaft 81 has moved to the communication side past the boundary position, and a predetermined gear ratio change rate (gear shift) is controlled by controlling the upshift valve 44 to a predetermined communication state. The speed ratio is controlled to the overdrive side (reference numeral a in FIG. 9B). In step S3, the spool valve shaft 86 of the downshift valve 49 starts a sweep operation toward the communication position. When the spool valve shaft 86 moves past the boundary position shown in FIG. 5B and moves in the direction of the arrow b, the hydraulic oil starts to be discharged through the open discharge port 85b (reference numeral b in FIG. 9B). The transmission speed of the transmission mechanism 14 gradually decreases. In the subsequent step S13, it is determined whether or not the absolute value of the speed change ratio is less than a predetermined value β. In this step S13, when the absolute value of the gear ratio change rate exceeds the predetermined value β, the sweep operation of the spool valve shaft 86 is continued, whereas when the absolute value of the gear ratio change rate is less than the predetermined value β ( In FIG. 9B, reference symbol b) proceeds to step S5, and the current value of the drive current supplied to the solenoid 54a of the pilot valve 54 is read. Since the current value read in step S5 is the current value when the spool valve shaft 86 moves past the boundary position, the current value when the spool valve shaft 86 is operated to the boundary position in the subsequent step S6. The read current value is corrected and recorded so as to be the current value.

  In this manner, the downshift valve 49 is swept while holding the upshift valve 44 in a predetermined communication state, or the upshift valve 44 is swept while holding the downshift valve 49 in a predetermined communication state. Even in this case, it is possible to learn the current value for controlling the spool valve shafts 81 and 86 to the boundary position by detecting the change rate of the transmission gear ratio accompanying the sweep operation.

  In the learning control shown in the flowcharts of FIGS. 6 and 8, the spool valve shafts 81 and 86 are separated from each other by reading the change of the hydraulic oil state from the change ratio of the transmission mechanism 14 and the change ratio of the transmission ratio. The driving current for controlling the position is learned. However, the present invention is not limited to this, and the learning control of the driving current is executed by directly detecting the fluctuation of the primary pressure Pp accompanying the sweep operation. Anyway. For example, by assembling a primary pressure sensor in the primary pressure path 45 or the like, the switching operation of the shift valves 44 and 49 may be determined from the change amount or change rate of the primary pressure Pp, and the drive current may be learned. Further, when the primary pressure sensor is assembled, there is no need to operate the transmission mechanism 14 to change the transmission gear ratio, so a clutch mechanism such as a fuse clutch 37 is provided between the transmission mechanism 14 and the drive wheel 17. Even if there is no continuously variable transmission, the present invention can be effectively applied.

  Further, since the relationship between the current value of the drive current supplied to the solenoids 53a and 54a and the control position of the spool valve shafts 81 and 86 driven by this drive current varies depending on various conditions, the battery voltage and the alternator power generation The learning control may be executed by dividing the amount (engine speed), hydraulic oil temperature, and the like for each predetermined condition. In this way, by learning the drive current for each of various vehicle conditions, it is possible to improve the response of shift control while avoiding unnecessary supply and discharge of hydraulic oil in any driving situation. It becomes.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the illustrated upshift valve 44 and downshift valve 49 are pilot operation valves whose operation state is controlled by the pilot fluid, but the present invention is not limited to this, and the upshift valve 44 or By incorporating solenoids 51a to 54a into the downshift valve 49, the upshift valve 44 and the downshift valve 49 may be configured as electromagnetic valves.

  In the learning control described above, the current value of the drive current is learned. However, when the pilot valves 53 and 54 are duty solenoid valves, the duty ratio for the solenoids 53a and 54a is learned. Needless to say. Furthermore, when determining the switching operation of the upshift valve 44 and the downshift valve 49, the upshift valve 44 and the downshift valve 49 are determined based on the same predetermined values α and β. Instead, a predetermined value for determining the switching operation of the upshift valve 44 and a predetermined value for determining the switching operation of the downshift valve 49 may be set separately.

  In the illustrated case, the primary pulley 20 functions as a transmission pulley and the secondary pulley 21 functions as a tightening pulley. However, the present invention is not limited to this, and the primary pulley 20 is used as a tightening pulley. The secondary pulley 21 may function as a speed change pulley. In this case, the upshift valve 44 and the downshift valve 49 are connected to the secondary pulley 21.

It is a skeleton figure which shows a continuously variable transmission. It is the schematic which shows the hydraulic control system and electronic control system of a continuously variable transmission. It is a block diagram which shows the transmission control system of a CVT control unit. (A)-(C) are explanatory drawings which show the process at the time of switching an upshift valve from a cutoff state to a communication state. (A)-(C) are explanatory drawings which show the process at the time of switching a downshift valve from the interruption | blocking state to a communication state. It is a flowchart which shows the procedure at the time of performing learning control. (A) And (B) is explanatory drawing which shows the fluctuation | variation state of the gear ratio accompanying learning control. It is a flowchart which shows the procedure of the learning control performed by the control apparatus which is other embodiment of this invention. (A) And (B) is explanatory drawing which shows the fluctuation | variation state of the gear ratio accompanying learning control.

Explanation of symbols

10 continuously variable transmission 20 primary pulley (transmission pulley)
21 Secondary pulley (clamping pulley)
22 Drive belt (power transmission element)
40 Oil pump (hydraulic supply source)
44 Upshift valve (first shift valve)
48 Oil pan 49 Downshift valve (second shift valve)
60 CVT control unit (valve driving means, learning control means)

Claims (5)

A transmission pulley and a tightening pulley around which the power transmission element is wound, a winding diameter of the power transmission element is controlled using the transmission pulley, and a tension of the power transmission element is controlled using the tightening pulley. A control device for a step transmission,
A first shift valve provided between a hydraulic pressure supply source and the transmission pulley, wherein the first shift valve is switched between a communication state for supplying hydraulic oil to the transmission pulley and a shut-off state for stopping the supply;
A second shift valve provided between the transmission pulley and the oil pan, wherein the second shift valve is switched between a communication state for discharging the hydraulic oil from the transmission pulley and a shut-off state for stopping the discharge;
A valve that changes the operating oil state in the transmission pulley by switching the operating state of the other shift valve from the shut-off state to the communicating state while maintaining the operating state of one of the first and second shift valves. Driving means;
Learning control means for determining a switching operation of the other shift valve based on the change in the hydraulic oil state, and learning a drive signal when the other shift valve is switched from the shut-off state to the communication state. A control device for a continuously variable transmission. The control device for a continuously variable transmission according to claim 1,
The learning control means determines a switching operation of the other shift valve based on a change in gear ratio or hydraulic pressure, and a control device for a continuously variable transmission. The control device for a continuously variable transmission according to claim 1 or 2,
The control device for a continuously variable transmission, wherein the valve driving means switches the other shift valve from a shut-off state to a communication state while holding the one shift valve in a shut-off state. The control device for a continuously variable transmission according to claim 1 or 2,
The control device for a continuously variable transmission, wherein the valve driving means switches the other shift valve from a shut-off state to a communication state while holding the one shift valve in a communication state. The control device for a continuously variable transmission according to any one of claims 1 to 4,
The learning control means learns a drive signal for each predetermined vehicle state, and is a control device for a continuously variable transmission.

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