JP2010112471A - Continuously variable transmission - Google Patents

Abstract

[PROBLEMS] To achieve both suppression of unnecessary upshifts and belt slippage in an extremely low vehicle speed range.
An ECU includes a vehicle traveling at an extremely low vehicle speed (YES in S102), a maximum gear ratio (YES in S104), and an initial start after engine start. If there is (YES in S106), a step of performing a slow duty down control (S112), a step of executing a duty down control (S110) if there is no initial start after engine start (NO in S104), When the vehicle is stopped (YES at S100), a step of executing the closing control (S108), and when not running at an extremely low vehicle speed (NO at S102), a step of executing the shift feedback control (NO at S102) S114) is executed.
[Selection] Figure 8

Description

  The present invention relates to a continuously variable transmission, and more particularly to hydraulic control of a belt type continuously variable transmission.

  An automatic transmission mounted on a vehicle includes a transmission mechanism that is connected to an engine via a torque converter or the like and has a plurality of power transmission paths. One example of an automatic transmission is a belt-type continuously variable transmission (CVT).

  As such a belt-type continuously variable transmission, Japanese Patent Application Laid-Open No. 2006-214555 (Patent Document 1) discloses a continuously variable transmission control device capable of preventing a decrease in driving force due to belt slippage or unnecessary upshift of the continuously variable transmission. Is disclosed. This continuously variable transmission control device is a continuously variable transmission control device that controls a belt-type continuously variable transmission that changes a gear ratio by changing the amount of oil in a primary pulley provided on the drive side. The primary pulley oil amount estimating means for estimating the change in the oil amount in the primary pulley using a physical model, and the oil amount estimated by the primary pulley oil amount estimating means when the vehicle speed becomes a predetermined value or less. A primary pulley oil amount control means for performing control to change the oil amount in the primary pulley so as to compensate for the change is provided.

  According to the continuously variable transmission control device disclosed in the above publication, when the vehicle speed becomes a predetermined value or less, the oil amount is compensated for the change in the oil amount in the primary pulley estimated using the physical model. Is changed. For this reason, it is possible to prevent a decrease in driving force due to an unnecessary upshift in the vehicle. As a result, the belt slippage of the continuously variable transmission can be prevented without causing a sudden downshift when the vehicle is started.

Further, the continuously variable transmission control device disclosed in the above publication drives the up-shift valve and the down-shift valve when the vehicle speed is extremely low with the vehicle gear ratio being maximum (low gear). The closing control is disclosed in which both the duty ratios of the actuators to be operated are set to zero and the shift control is stopped.
JP 2006-214555 A

  In the continuously variable transmission control device disclosed in the above-mentioned publication, the amount of hydraulic oil flowing into the primary pulley by adding a correction amount to the shift command value when a moderate upshift is performed by the closing control. By reducing, unnecessary upshifts are suppressed.

  However, there is a problem that the fluctuation of the hydraulic pressure has an indefinite response delay with respect to the output of the shift command value due to the influence of the oil temperature and the like. In particular, when the vehicle is traveling at an extremely low vehicle speed with low detection accuracy of the vehicle speed, or when a correction amount is added based on the estimated hydraulic pressure of the primary hydraulic pressure, there may be a significant response delay of the hydraulic pressure. Therefore, there are cases where it is not possible to achieve both suppression of unnecessary upshifting and suppression of belt slippage.

  The present invention has been made to solve the above-described problems, and its object is to provide a continuously variable transmission that achieves both suppression of unnecessary upshifting and belt slippage in an extremely low vehicle speed range. Is to provide a machine.

  A continuously variable transmission according to a first invention is a continuously variable transmission mounted on a vehicle having at least an engine as a drive source. This continuously variable transmission generates a driving pulley, a driven pulley, a belt wound around the driving pulley and the driven pulley, an actuator that changes the groove width of the driving pulley with the operating hydraulic pressure, and an operating hydraulic pressure. Hydraulic pressure source, speed detecting means for detecting the speed of the vehicle, speed ratio detecting means for detecting the gear ratio of the continuously variable transmission, supply amount of hydraulic oil to the actuator, and hydraulic oil from the actuator An adjusting means for adjusting at least one of the discharge amount and the vehicle is in a stopped state, or the speed of the vehicle is equal to or lower than a predetermined speed and the speed ratio is the vehicle When the first condition that the gear ratio does not correspond to when the vehicle starts is satisfied, the discharge of the hydraulic fluid from the actuator is stopped, and the first hydraulic pressure at which the belt does not slip is A first control means for controlling the adjusting means so that the supplied amount is held, and the detected vehicle speed is equal to or lower than a predetermined speed, and the detected gear ratio is determined when the vehicle starts. Supply in which a second operating hydraulic pressure that is lower than the first operating hydraulic pressure is maintained when the second condition of the corresponding gear ratio and the first start after the engine is started is satisfied. And a second control means for controlling the adjusting means so as to be the amount and the discharge amount.

  According to the first invention, the speed of the vehicle is equal to or lower than a predetermined speed, the detected gear ratio is a gear ratio corresponding to the start of the vehicle, and the first start after the engine is started. Upshift by controlling the adjusting means so that the second operating hydraulic pressure lower than the first operating hydraulic pressure is maintained to be the supply amount and the discharge amount when the second condition is satisfied Therefore, it is possible to continuously generate the hydraulic pressure that can achieve both suppression of belt slippage and belt slippage. In particular, by performing control in which the second operating oil pressure is maintained while in the extremely low vehicle speed region, fluctuations in the oil pressure are suppressed, so that it is possible to avoid the influence caused by a delay in response of the oil pressure or the like. . Further, the vehicle may move due to disturbance while the engine is stopped, and the detection accuracy of the gear ratio may deteriorate. Therefore, the occurrence of belt slip can be reliably suppressed by performing the control that maintains the second hydraulic pressure at the first start after the engine is started. Therefore, it is possible to provide a continuously variable transmission that achieves both suppression of unnecessary upshifting and suppression of belt slippage in an extremely low vehicle speed region.

  In the continuously variable transmission according to the second aspect of the invention, in addition to the configuration of the first aspect of the invention, the adjusting means connects the first oil path connecting the hydraulic power source and the actuator between the communication state and the cutoff state. A first switching valve that switches from either state to the other state, a second oil passage that connects the hydraulic oil discharge passage and the actuator, and a second fluid passage that connects the hydraulic source and the actuator. One state of the 1st state which makes the 3rd oil way shut off state, and the 2nd state which makes the 2nd oil way the shut off state, and makes the 3rd oil way the communication state To the other state through a transition state where both the second oil passage and the third oil passage are in communication, a second oil pressure source of the third oil passage, and a second oil passage The hydraulic pressure supplied from the hydraulic pressure source is set at a position between the switching valve and a predetermined hydraulic pressure. Further comprising a control pressure regulating valve. The second control means controls the first and second switching valves so that the first oil passage is shut off and the transition state continues when the second condition is satisfied.

  According to the second invention, when the vehicle speed is equal to or less than a predetermined value, the gear ratio is a gear ratio corresponding to the start of the vehicle, and is the first start after the engine is started. In addition, by continuing the transition state, the hydraulic oil is discharged from the actuator while the supply of the hydraulic oil to the actuator via the pressure regulating valve is continued. Therefore, it is possible to achieve a balance between the amount of hydraulic oil supplied to the actuator and the amount of hydraulic oil discharged from the actuator. Therefore, the operating hydraulic pressure in the actuator can be held at the second operating hydraulic pressure. By keeping the operating hydraulic pressure of the actuator constant at the second operating hydraulic pressure, it is possible to continuously generate an operating hydraulic pressure that can achieve both suppression of upshifting and suppression of belt slip. Therefore, it is possible to suppress the occurrence of belt slip while suppressing an unnecessary upshift. In particular, since the fluctuation of the hydraulic pressure is suppressed by performing the control that continues the transition state while the vehicle is in the extremely low vehicle speed region, it is possible to avoid the influence caused by the response delay of the hydraulic pressure. Furthermore, since the vehicle may move due to a disturbance while the engine is stopped and the detection accuracy of the gear ratio may deteriorate, by performing control to continue the transition state at the first start after the engine is started, Generation | occurrence | production can be suppressed reliably.

  In the continuously variable transmission according to the third invention, in addition to the configuration of the second invention, the second control means includes the flow rate of the hydraulic oil in the second oil passage and the third oil passage in the transition state. The second switching valve is controlled so that the flow rate of the hydraulic oil is a flow rate that suppresses both shifting to the speed increasing side of the continuously variable transmission and slipping of the belt.

  According to the third invention, by continuing the transition state, the hydraulic oil is discharged from the actuator while the supply of the hydraulic oil to the actuator via the pressure regulating valve is continued. By controlling the flow rate of hydraulic oil in the second and third oil passages so as to suppress shifting to the speed increasing side of the continuously variable transmission and belt slip, the amount of hydraulic oil supplied to the actuator and It is possible to balance the amount of hydraulic oil discharged. Therefore, the working hydraulic pressure in the actuator can be made constant. By making the hydraulic pressure of the actuator constant, it is possible to continuously generate hydraulic pressure that achieves both suppression of upshifting and suppression of belt slip. Therefore, it is possible to suppress the occurrence of belt slip while suppressing an unnecessary upshift.

  In the continuously variable transmission according to the fourth invention, in addition to the configuration of the second or third invention, the first control means shuts off the first oil passage when the first condition is satisfied. And the first and second switching valves are controlled so that the third oil passage is in a communicating state.

  According to the fourth aspect of the present invention, when the vehicle is in a stopped state, or the speed of the vehicle is equal to or lower than a predetermined speed, and the speed ratio is not a speed ratio corresponding to the start of the vehicle (that is, the belt is When the vehicle has not moved to the corresponding position at the time of starting), the hydraulic pressure generated in the hydraulic power source passes through the pressure regulating valve by closing the first oil passage and connecting the third oil passage. Thus, it is supplied to the actuator. Therefore, it is possible to secure the first hydraulic pressure that suppresses belt slip in the actuator.

  A continuously variable transmission according to a fifth aspect of the invention includes a first control valve for controlling a switching operation of the first switching valve using hydraulic pressure, in addition to the configuration of any one of the second to fourth aspects of the invention. And a second control valve for controlling the switching operation of the second switching valve using hydraulic pressure. The first and second control means control the first switching valve using the first control valve, and control the second switching valve using the second control valve.

  According to the fifth aspect, by using the first control valve and the second control valve, a desired switching operation can be realized in the first switching valve and the second switching valve.

  A continuously variable transmission according to a sixth aspect of the present invention is the continuously variable transmission according to any one of the second to fifth aspects, wherein the detected vehicle speed is equal to or lower than a predetermined speed, and the detected gear ratio is When the third condition that the gear ratio corresponds to when the vehicle starts and is not the first time after starting the engine is satisfied, the first oil passage is shut off, and the second It further includes third control means for controlling the first and second switching valves so as to bring the oil passage into a communication state.

  According to the sixth aspect of the invention, when the start is not the first start after the engine is started and the detected speed change ratio is the speed change ratio corresponding to the start of the vehicle, the belt is adapted for the start time. It can be said that it has moved to the position to be. For this reason, when the vehicle speed is equal to or lower than a predetermined speed, the first oil passage is shut off and the second oil passage is brought into communication so that the gear ratio corresponding to the start of the vehicle can be achieved. Can be held. Therefore, it is possible to suppress a decrease in driving force.

  The continuously variable transmission according to the seventh aspect of the invention further includes oil temperature detection means for detecting the temperature of the hydraulic oil in addition to the configuration of any one of the first to sixth aspects of the invention. The second control means is more than the hydraulic pressure in the actuator when the hydraulic pressure in the actuator is a second temperature higher than the first temperature when the detected temperature of the hydraulic oil is the first temperature. The adjustment means is controlled so as to be higher.

  According to the seventh invention, the hydraulic pressure in the actuator when the temperature of the hydraulic oil is the first temperature is higher than the hydraulic pressure in the actuator when the temperature is the second temperature higher than the first temperature. By controlling the adjusting means as described above, the amount of hydraulic oil supplied to the actuator and the amount of hydraulic oil discharged from the actuator can be made to correspond to characteristics such as viscosity with respect to the temperature of the hydraulic oil. Therefore, the balance between the supply amount and discharge amount of the hydraulic oil in the actuator can be achieved with high accuracy.

  In the continuously variable transmission according to the eighth aspect of the invention, in addition to the configuration of any one of the first to seventh aspects, the predetermined speed is a speed that cannot be detected with an accuracy greater than or equal to a predetermined degree by the speed detecting means. It is.

  According to the eighth invention, since it is difficult to perform a shift corresponding to the speed of the vehicle while in the extremely low vehicle speed region below the speed that cannot be detected with the accuracy more than the predetermined degree by the speed detecting means, By controlling the first switching valve and the second switching valve in accordance with whether the vehicle is stopped, the engine starting state, and the belt state based on the gear ratio, unnecessary upshifts and belt slips can be suppressed. Can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a power train of a vehicle on which a continuously variable transmission according to the present embodiment is mounted will be described. The continuously variable transmission according to the present embodiment is a belt type continuously variable transmission.

  As shown in FIG. 1, the power train of the vehicle includes an engine 100, a continuously variable transmission 350, and a differential gear 800.

  The continuously variable transmission 350 includes a torque converter 200, a forward / reverse switching device 290, a belt-type continuously variable transmission mechanism 300, an ECU (Electronic Control Unit) 1000, and a hydraulic control unit 1100.

  The output shaft of engine 100 is connected to the input shaft of torque converter 200. Engine 100 and torque converter 200 are connected by a rotating shaft. Therefore, engine 100 output shaft rotational speed NE (engine rotational speed NE) detected by engine rotational speed sensor 432 and torque converter 200 input shaft rotational speed (pump rotational speed) are the same.

  The torque converter 200 includes a lock-up clutch 210 that directly connects the input shaft and the output shaft, a pump impeller 220 on the input shaft side, a turbine impeller 230 on the output shaft side, and a one-way clutch 250. It is comprised from the stator 240 which expresses an amplification function. Torque converter 200 and belt type continuously variable transmission mechanism 300 are connected by a rotating shaft. The output shaft rotational speed NT (turbine rotational speed NT) of the torque converter 200 is detected by the turbine rotational speed sensor 400.

  An oil pump 260 is provided between the torque converter 200 and the belt type continuously variable transmission mechanism 300. The oil pump 260 is a gear pump, for example, and operates as the pump impeller 220 on the input shaft side rotates. The oil pump 260 supplies hydraulic pressure to the line pressure control unit 1130.

  Belt type continuously variable transmission mechanism 300 is connected to torque converter 200 with forward / reverse switching device 290 interposed. The belt-type continuously variable transmission mechanism 300 includes a primary pulley 500 on the input side (drive side), a secondary pulley 600 on the output side (driven side), and a metal circle wound around the primary pulley 500 and the secondary pulley 600. And an annular belt 700.

  The belt 700 is formed by annularly arranging a plurality of elements having contact surfaces with the primary pulley 500 and the secondary pulley 600.

  Primary pulley 500 includes a fixed sheave fixed to primary shaft 502 and a movable sheave supported on primary shaft 502 so as to be slidable only. The secondary pulley 600 includes a fixed sheave fixed to the secondary shaft 602 and a movable sheave supported on the secondary shaft 602 so as to be slidable only.

  Hydraulic oil is supplied to and discharged from the hydraulic actuator (1) 550 of the primary pulley 500. In addition, hydraulic oil is supplied to and discharged from the hydraulic actuator (2) 650 of the secondary pulley 600. The speed change is performed by continuously changing the groove width between the fixed sheave and the movable sheave of each of the pulleys 500 and 600 so that the belt winding radius is changed to a large or small size.

  The hydraulic control unit 1100 supplies the hydraulic pressure (hereinafter, referred to as primary hydraulic pressure) supplied to the hydraulic actuator (1) 550 of the primary pulley 500 so that the speed ratio of the primary pulley 500 matches the target rotational speed. To control. Further, the hydraulic control unit 1100 presses the movable sheave of the secondary pulley 600 toward the fixed sheave side to pinch the belt so as to develop a tension necessary for transmitting torque, so that the hydraulic actuator (2) of the secondary pulley 600 is obtained. The hydraulic pressure supplied to 650 (hereinafter referred to as secondary hydraulic pressure) is controlled.

  The rotation speed NIN of the primary pulley 500 of the belt-type continuously variable transmission mechanism 300 (hereinafter referred to as primary pulley rotation speed NIN) is detected by the primary pulley rotation speed sensor 410 and the rotation speed NOUT of the secondary pulley 600 (hereinafter referred to as secondary). The pulley rotation speed NOUT) is detected by the secondary pulley rotation speed sensor 420.

  These rotation speed sensors are provided to face the teeth of the rotation detection gear attached to the rotation shafts of the primary pulley 500 and the secondary pulley 600 and the drive shaft connected thereto. These rotational speed sensors are sensors that can also detect slight rotations of the primary pulley 500 that is an input shaft and the secondary pulley 600 that is an output shaft of the belt-type continuously variable transmission mechanism 300. It is a sensor using a magnetoresistive element called a type sensor.

  The forward / reverse switching device 290 includes a double pinion planetary gear, a reverse (reverse) brake B1 and an input clutch C1. In the planetary gear, its sun gear is connected to the input shaft, the carrier CR supporting the first and second pinions P1, P2 is connected to the primary side fixed sheave, and the ring gear R is a reverse friction engagement element. The reverse brake B1 is connected, and an input clutch C1 is interposed between the carrier CR and the ring gear R. This input clutch C1 is also called a forward clutch or a forward clutch, and is always used in an engaged state when a vehicle other than the parking (P) position, the R position, and the N position moves forward.

  The ECU 1000 and the hydraulic control unit 1100 that control the continuously variable transmission 350 will be described. ECU 1000 has a signal representing turbine speed NT from turbine speed sensor 400, a signal representing primary pulley speed NIN from primary pulley speed sensor 410, and a secondary pulley speed NOUT from secondary pulley speed sensor 420. Each signal is input. ECU 1000 calculates the gear ratio from gear ratio = primary pulley rotation speed NIN / secondary pulley rotation speed NOUT.

  The hydraulic control unit 1100 includes a transmission speed control unit 1110, a belt clamping pressure control unit 1120, a line pressure control unit 1130, a lockup engagement pressure control unit 1132, a clutch pressure control unit 1140, and a manual valve 1150. Including. ECU 1000 includes a shift control duty solenoid (1) 1200 (hereinafter referred to as DS (1) 1200) and a shift control duty solenoid (2) 1210 (hereinafter referred to as DS (2) 1210) of hydraulic control unit 1100. Control signals are output to the belt clamping pressure control linear solenoid 1220, the line pressure control linear solenoid 1230, and the lockup engagement pressure control duty solenoid 1240.

  The shift speed control unit 1110 controls the inflow amount of the hydraulic oil into the hydraulic actuator (1) 550 of the primary pulley 500 by the DS (1) 1200 according to the vehicle speed based on the wheel speed and the accelerator opening, and increases the speed. Side shift speed is controlled. Further, the shift speed control unit 1110 controls the amount of hydraulic oil flowing out from the hydraulic actuator (1) 550 of the primary pulley 500 by the DS (2) 1210 according to the wheel speed and the accelerator opening, Control the shifting speed. Shift control is performed by controlling the inflow and outflow of hydraulic fluid to the hydraulic actuator (1) 550 of the primary pulley 500 by the shift speed control unit 1110.

  The belt clamping pressure control unit 1120 controls the hydraulic pressure supplied to the hydraulic actuator (2) 650 of the secondary pulley 600 by the belt clamping pressure control linear solenoid 1220 according to the input torque of the primary pulley 500 and the gear ratio. Control the belt clamping pressure. The input torque may be estimated from, for example, the output torque of the engine 100 based on the accelerator pedal depression amount, the throttle opening, the engine speed or the intake air amount, and the torque ratio in the torque converter 200, or directly. May be detected automatically.

  The line pressure control unit 1130 controls the line pressure by the line pressure control linear solenoid 1230 from the instruction value for the belt clamping pressure control linear solenoid 1220 corresponding to the belt clamping pressure and the primary hydraulic pressure (estimated value or actual measurement value).

  In this embodiment, the “line pressure” is the hydraulic pressure supplied to the hydraulic actuator (1) 550 and the original pressure of the hydraulic pressure supplied to the hydraulic actuator (2) 650, and the hydraulic pressure supplied by the oil pump 260. Is a hydraulic pressure regulated by a regulator valve (not shown) and a linear solenoid 1230 for line pressure control.

  The line pressure controlled by the line pressure control unit 1130 is supplied to the DS (1) 1200, DS (2) 1210, and the belt clamping pressure control linear solenoid 1220. The primary hydraulic pressure and the secondary hydraulic pressure are controlled using the supplied line pressure.

  The lockup engagement pressure control unit 1132 controls switching between engagement and disengagement of the lockup clutch 210 and gradual increase and decrease of the engagement pressure of the lockup clutch 210 by the lockup engagement pressure control duty solenoid 1240. .

  The manual valve 1150 operates in conjunction with the driver's operation of the shift lever to switch the oil passage. The clutch pressure control unit 1140 controls the hydraulic pressure supplied via the manual valve 1150 by the line pressure control linear solenoid 1230 when the input clutch C1 or the reverse brake B1 is engaged.

  ECU 1000 further includes a signal representing the vehicle speed from wheel speed sensor 440, a signal representing the amount of depression of the accelerator pedal from accelerator position sensor 442, and the temperature of hydraulic oil in continuously variable transmission 350 from oil temperature sensor 444. And a signal representing the engine speed (NE) of the engine 100 are input from the engine speed sensor 432, respectively. ECU 1000 includes a CPU (Central Processing Unit) (not shown) and memory 1002. Various information, programs, threshold values, maps, and the like are stored in the memory 1002, and data is read or stored by the CPU as necessary.

  Wheel speed sensor 440 detects the number of rotations of a wheel (not shown). Wheel speed sensor 440 transmits a wheel speed signal indicating the detected number of rotations of the wheel to ECU 1000. In the present embodiment, as long as the vehicle speed can be detected, the present invention is not particularly limited to detecting the rotational speed of the wheel. For example, the secondary pulley rotational speed and the reduction ratio from the continuously variable transmission to the drive wheel The vehicle speed may be calculated based on the above.

  In this belt type continuously variable transmission, a belt is wound around a driving pulley (input shaft pulley, primary pulley) and a driven pulley (output shaft pulley, secondary pulley) each having a V-groove pulley groove. By enlarging the width of the pulley groove of the pulley and simultaneously reducing the width of the pulley groove of the other pulley, the belt wrapping radius (effective diameter) for each pulley is continuously changed, so that there is no gear ratio. Configured to set stage. The torque transmitted in this belt type continuously variable transmission is a torque corresponding to the load acting in the direction in which the belt and the pulley come into contact with each other. Therefore, the belt is clamped by the pulley so as to apply tension to the belt. Yes.

  Further, as described above, the speed change is performed by enlarging and reducing the width of the pulley groove. Specifically, each pulley is constituted by a fixed sheave and a movable sheave. Is shifted by moving it back and forth in the axial direction by a hydraulic actuator provided on the back side thereof.

  In such a continuously variable transmission, the pulley width of the input shaft pulley is small (the pulley diameter is large), the pulley width of the output shaft pulley is large (the pulley diameter is small), and the rotation speed of the output shaft pulley is the input shaft pulley. When the rotation speed is higher than the rotation speed, the speed increase is called acceleration. The pulley width of the input shaft pulley is large (the pulley diameter is small), the pulley width of the output shaft pulley is small (the pulley diameter is large), and the rotation speed of the output shaft pulley is The case where the rotational speed of the input shaft pulley is lower is called deceleration. The case where the pulley width of the input shaft pulley is the largest (the pulley diameter is the smallest) and the pulley width of the output shaft pulley is the smallest (the pulley diameter is the largest) is referred to as the maximum deceleration state.

  With reference to FIG. 2, shift speed control unit 1110 that performs shift control of continuously variable transmission 350 will be described. The shift speed control unit 1110 adjusts at least one of the amount of hydraulic oil supplied to the hydraulic actuator (1) and the amount of hydraulic oil discharged from the hydraulic actuator (1). The shift speed control means 1110 corresponds to “adjustment means”. Supply and discharge of hydraulic fluid to and from the hydraulic actuator (1) 550 is performed by flow control. The valve mechanism for that purpose is configured as shown in FIG. That is, the shift speed control unit 1110 includes a shift control valve (1) 1500 for supplying the line pressure PL to the hydraulic actuator (1) 550, a shift control valve (2) 1600 connected to the drain, and a pressure regulating valve 1700. Including.

  The shift control valve (1) 1500 is a valve for performing an upshift, and is communicated with an input port 1502 to which a line pressure PL is supplied via an oil passage 1300 and a hydraulic actuator (1) 550. The output port 1504 includes a spool 1508 that opens and closes a flow path between the input port 1502 and the output port 1504. The oil passage 1300 is connected to a line pressure control unit 1130, and the oil passage 1300 is supplied with a hydraulic pressure in which the original pressure generated in the oil pump 260 is adjusted to the line pressure PL by the line pressure control unit 1130.

  A spring 1510 is disposed on one end side of the spool 1508 and a signal pressure port 1506 for applying a signal pressure is formed on the other end side of the spool 1508. A signal pressure port 1512 for applying a signal pressure is formed on one end side of the spool 1508 where the spring 1510 is disposed.

  DS (1) 1200 that adjusts the output pressure in accordance with a signal indicating the duty value received from ECU 1000 is connected to signal pressure port 1506. In addition, DS (2) 1210 that adjusts the output pressure in accordance with a signal indicating the duty value received from ECU 1000 is connected to signal pressure port 1512.

  Therefore, the signal pressure output from the DS (1) 1200 is applied to the signal pressure port 1506 on the other end side of the spool 1508, and the signal pressure output from the DS (2) 1210 is applied to the signal pressure port 1512. The

  That is, the hydraulic oil applied to the signal pressure port 1506 on the other end side of the spool 1508 is increased to switch the input port 1502 and the output port 1504 of the transmission control valve (1) 1500 from the shut-off state to the communication state, so that the hydraulic oil Is supplied from the output port 1504 to the hydraulic actuator (1) 550. By supplying hydraulic pressure to the hydraulic actuator (1) 550, the groove width of the primary pulley 500 becomes narrow, and as a result, the gear ratio decreases. That is, it is upshifted.

  Further, the shift control valve (2) 1600 is a valve for performing a downshift, and is regulated using the first port 1604 communicated with the hydraulic actuator (1) 550 and the line pressure PL as an original pressure. It includes a second port 1602 to which hydraulic pressure is supplied, a drain port 1612, and a spool 1608 that connects the first port 1602 with at least one of the second port 1604 and the drain port 1612.

  The spool 1608 is provided so as to be slidable within the casing of the valve that houses the spool 1608. A plurality of protrusions are formed on the spool 1608 so as to come into contact with the inner wall surface of the valve housing. When the spool 1608 moves so that these protrusions block at least one of the first port 1602, the second port 1604, and the drain port 1612, the first port 1602 and the second port 1604 communicate with each other. Or the second port 1604 and the drain port 1612 are made to communicate with each other. In particular, the protrusion 1616 provided on the spool 1608 is separated from the wall surface inside the casing of the valve so as to be positioned in the downward direction in FIG. 2 (that is, has a gap with the wall surface inside the casing). It is formed.

  A spring 1610 is disposed on one end side of the spool 1608 and a signal pressure port 1606 for applying a signal pressure is formed on the other end side of the spool 1608. A signal pressure port 1614 for applying a signal pressure is formed on one end side of the spool 1608 where the spring 1610 is disposed.

  The DS (2) 1210 is connected to the signal pressure port 1606. The DS (1) 1200 is connected to the signal pressure port 1614.

  Therefore, the signal pressure output from the DS (2) 1210 is applied to the signal pressure port 1606 on the other end side of the spool 1608, and the signal pressure output from the DS (1) 1200 is applied to the signal pressure port 1614. The

  In other words, the hydraulic oil applied to the signal pressure port 1606 on the other end side of the spool 1608 is increased to cause the first port 1604 to communicate with the drain port 1612, whereby hydraulic oil is discharged from the hydraulic actuator (1) 550. As the hydraulic oil is discharged from the hydraulic actuator (1) 550, the groove width of the primary pulley 500 is widened, and as a result, the gear ratio is increased. That is, it is downshifted.

  A pressure regulating valve 1700 is connected to the second port 1602 of the transmission control valve (2) 1600. In the pressure regulating valve 1700, an input port 1706 to which a line pressure PL is supplied is formed on the front side of a piston 1704 pressed by a spring 1702, and an output in which the front side and the back side of the piston 1704 communicate with each other. A valve having a port 1708. The output port 1708 is in communication with the second port 1602 of the transmission control valve (2) 1210. A line pressure PL is supplied to the input port 1706 via an orifice 1710 having a small opening area. That is, the pressure regulating valve 1700 is configured such that a hydraulic pressure obtained by subtracting a pressure corresponding to the elastic force of the spring 1702 from the line pressure PL is generated at the output port 1708, that is, the second port 1602 of the transmission control valve (2) 1210. Yes.

  In the continuously variable transmission 350 having the above-described configuration, the present invention is directed to the vehicle in which the vehicle is in a stopped state, or the vehicle speed is equal to or less than a predetermined speed Va, and the gear ratio is the vehicle. When the first condition that the gear ratio does not correspond to when the vehicle is started is satisfied, the discharge of the hydraulic oil from the hydraulic actuator (1) 550 is stopped, and the first hydraulic pressure at which the belt 700 does not slip The shift speed control unit 1110 is controlled so that the supplied amount is maintained, and the detected vehicle speed is equal to or lower than a predetermined speed Va, and the detected gear ratio corresponds to the time when the vehicle starts. And a second supply hydraulic pressure that is lower than the first hydraulic pressure when the second condition is satisfied, that is, when the engine is started for the first time after the engine 100 is started, Emission amount ECU1000 way has a feature in that to control the shift speed control unit 1110.

  Specifically, when the second condition is satisfied, the oil passage (1) connecting the hydraulic power source to the hydraulic actuator (1) 550 via the transmission control valve (1) 1500 is shut off, and A hydraulic pressure source is connected via an oil passage (2) connecting a hydraulic oil discharge passage to a hydraulic actuator (1) 550 via a transmission control valve (2) 1600, and a pressure regulating valve 1700 and a transmission control valve (2) 550. The ECU 1000 uses the DS (1) 1200 and the DS (2) 1210 so that the oil passage (3) connected to the hydraulic actuator (1) 550 continues to be in the communication state. 1500 and the shift control valve (2) 1600 are controlled.

  The “speed ratio corresponding to the start of the vehicle” is the maximum speed ratio in the continuously variable transmission 350 and the speed ratio at which the winding radius of the belt 700 is minimum in the primary pulley 500. That is, the “transmission ratio corresponding to the start of the vehicle” is the transmission ratio when the continuously variable transmission 350 is in the maximum deceleration state.

  In this embodiment, the oil passage (1) is connected from the oil passage 1300 to the hydraulic actuator (1) 550 via the input port 1502 and the output port 1504 when the input port 1502 and the output port 1504 are in communication. It is an oil passage.

  In the present embodiment, the oil passage (2) is an oil passage from the drain port 1612 to the hydraulic actuator (1) 550 via the second port 1604 when the drain port 1612 and the second port 1604 are in communication. It is.

  In the present embodiment, the oil passage (3) passes through the pressure regulating valve 1700, the first port 1602, and the second port 1604 from the oil passage 1300 when the first port 1602 and the second port 1604 are in communication. This is an oil passage to the hydraulic actuator (1) 550.

  ECU 1000 outputs a signal indicating the duty value to DS (1) 1200, and outputs a signal indicating the duty value to DS (2) 1210.

  In this embodiment, when ECU 1000 outputs a signal indicating a duty value of 0% to DS (1) 1200, shift control valve (1) 1500 is in the state on the left side of FIG. At this time, the input port 1502 and the output port 1504 are cut off. Therefore, the supply of the line pressure PL from the oil passage 1300 to the hydraulic actuator (1) 550 is interrupted.

  In addition, when ECU 1000 outputs a signal indicating a duty value of 100% to DS (1) 1200, transmission control valve (1) 1500 is in the state on the right side of FIG. At this time, the input port 1502 and the output port 1504 are in a communication state. Therefore, the line pressure PL is supplied from the oil passage 1300 to the hydraulic actuator (1) 550.

  When the ECU 1000 changes the output value between 0% and 100% with respect to DS (1) 1200, the spool 1508 of the shift control valve (1) 1500 is in the state shown on the right side of FIG. It becomes a state between the states on the left side.

  Similarly, when ECU 1000 outputs a signal indicating a duty value of 0% to DS (2) 1210, shift control valve (2) 1600 is in the state on the left side of FIG. At this time, the first port 1602 and the second port 1604 are in a communicating state, and the second port 1604 and the drain port 1612 are in a blocking state. Therefore, the line pressure PL is supplied from the oil passage 1300 to the hydraulic actuator (1) 550 via the pressure regulating valve 1700.

  In addition, when ECU 1000 outputs a signal indicating a duty value of 100% to DS (2) 1200, shift control valve (2) 1600 is in the state on the right side of FIG. At this time, the first port 1602 and the second port 1604 are cut off, and the second port 1604 and the drain port 1612 are in communication. Further, the drain port 1612 and the hydraulic actuator (1) 550 are in communication with each other. Therefore, the hydraulic oil of the hydraulic actuator (1) 550 is discharged via the drain port 1612.

  When ECU 1000 changes the output value between 0% and 100% with respect to DS (2) 1200, spool 1608 of transmission control valve (2) 1600 is in the state shown on the right side of FIG. Transition to the state on the left side.

  In particular, when DS (2) 1200 is in the transition state and the protrusion 1616 of the spool 1608 is at the position indicated by the broken line in FIG. 2, the first port 1602 and the second port 1604 are The second port and the drain port 1612 communicate with each other. That is, when DS (2) 1210 is in the transition state, both the oil passage (2) and the oil passage (3) may be in a communication state.

  In the present embodiment, ECU 1000 determines the flow rate of hydraulic oil in oil passage (2) and the flow of hydraulic oil in oil passage (3) in a transition state where both oil passage (2) and oil passage (3) are in communication. The shift control valve (2) 1600 is controlled so that the flow rate is a flow rate at which both the shift to the speed increasing side of the continuously variable transmission 350 and the slip of the belt 700 are suppressed.

  ECU 1000 determines the oil path when the vehicle is in a stopped state or when the vehicle speed is equal to or lower than a predetermined speed Va and the gear ratio is not a gear ratio corresponding to the start of the vehicle. The shift control valve (1) 1500 and the shift control valve (2) 1600 are controlled so that (1) is in a shut-off state and the oil passage (3) is in a communicating state.

  Further, ECU 1000 detects the speed of the vehicle at a predetermined speed Va or less, and the gear ratio is a gear ratio corresponding to the start of the vehicle, and at the first start after engine 100 is started. If not, the transmission control valve (1) 1500 and the transmission control valve (2) 1600 are controlled so that the oil passage (1) is shut off and the oil passage (2) is in communication.

  In the present embodiment, the predetermined speed Va is a speed that cannot be detected with an accuracy equal to or higher than a predetermined degree by the wheel speed sensor 440 or the secondary pulley rotation speed sensor 420, and is, for example, 2 km. However, it is not particularly limited to this.

  FIG. 2 shows a functional block diagram of ECU 1000 of continuously variable transmission 350 according to the present embodiment. ECU 1000 includes a stop determination unit 1400, an extremely low speed travel determination unit 1402, a transmission ratio determination unit 1404, a start determination unit 1406, a transmission feedback control unit (hereinafter referred to as a transmission FB control unit) 1408, and a closed state. A control unit 1410, a duty down control unit 1412, and a slow duty down control unit 1414 are included.

  The stop determination unit 1400 determines whether or not the vehicle is stopped. For example, the stop determination unit 1400 determines whether or not the vehicle is stopped based on the output value of the wheel speed sensor 440 or the secondary pulley rotation speed sensor. For example, when the stop determination unit 1400 does not receive a signal from the wheel speed sensor 440 or the secondary pulley rotation speed sensor 420, the stop determination unit 1400 determines that the vehicle is stopped and receives a signal from the wheel speed sensor 440 or the secondary pulley rotation speed sensor 420. If received, it is determined that the vehicle has not stopped. For example, the stop determination unit 1400 may turn on the stop determination flag when determining that the vehicle is stopped, and turn off the stop determination flag when the vehicle is not stopped.

  The extremely low speed traveling determination unit 1402 determines whether or not the vehicle is traveling at an extremely low speed. Specifically, when the extremely low speed traveling determination unit 1402 can determine that the vehicle speed is equal to or higher than a predetermined speed Va based on a signal from the wheel speed sensor 440 or the secondary pulley rotation speed sensor 420, the vehicle If it is determined that the vehicle is not traveling at an extremely low speed and it cannot be determined that the vehicle speed is equal to or higher than a predetermined speed Va, it is determined that the vehicle is traveling at an extremely low speed. For example, when it is determined that the vehicle is traveling at an extremely low speed, the extremely low speed traveling determination unit 1402 turns on the extremely low speed traveling determination flag, and when it is determined that the vehicle is at or above a predetermined speed Va, the extremely low speed traveling determination unit 1402 turns on. The determination flag may be turned off.

  The gear ratio determination unit 1404 determines whether or not the gear ratio in the continuously variable transmission mechanism 300 is a gear ratio corresponding to the start. That is, the gear ratio determination unit 1404 determines whether or not the gear ratio calculated from the ratio between the primary pulley rotation speed and the secondary pulley rotation speed is the maximum gear ratio (speed ratio corresponding to the most decelerated state). Note that the gear ratio determination unit 1404 is able to detect when the vehicle is stopped or when the secondary pulley rotation speed cannot be detected with an accuracy higher than a predetermined level by the secondary pulley rotation speed sensor 420. It is determined whether or not the most recent gear ratio is the maximum gear ratio. The gear ratio is stored in the memory 1002 every time it is detected. Note that the gear ratio determination unit 1404 may turn on the gear ratio determination flag if the gear ratio is the maximum gear ratio, and turn off the gear ratio determination flag if the gear ratio is not the maximum gear ratio, for example. .

  Start determination unit 1406 determines whether or not the vehicle has started for the first time after engine 100 has started. The start determination unit 1406 turns on the start flag when the vehicle starts, and turns off the start flag when the engine 100 stops. Therefore, start determination unit 1406 determines that the vehicle has started for the first time after engine 100 has started if engine 100 has been started and the start flag is off. For example, if start determination unit 1406 determines that the vehicle is starting for the first time after engine 100 is started, the start determination flag is turned on, and if it is determined that the vehicle is not starting for the first time after engine 100 is started. The start determination flag may be turned off.

  The shift FB control unit 1408 performs shift FB control when the vehicle is not stopped and is not traveling at an extremely low vehicle speed. Specifically, the shift FB control unit 1408 sets the duty values for DS (1) 1200 and DS (2) 1210 so that the primary pulley rotation speed (or transmission gear ratio) becomes the target rotation speed (or target transmission gear ratio). Feedback control. For example, when the accelerator pedal is depressed and the output of engine 100 increases, shift FB control unit 1408 performs duty up control and upshifts continuously variable transmission 350.

  During the upshift, the transmission FB control unit 1408 increases the signal pressure applied from the DS (1) 1200 to the signal pressure port 1506 by setting the duty value output to the DS (1) 1200 to 100%. The spool 1508 is in the state on the right side of FIG.

  Further, the transmission FB control unit 1408 reduces the signal pressure applied from the DS (2) 1210 to the signal pressure port 1606 by setting the duty value output to the DS (2) 1210 to 0%. 1608 becomes the state on the left side of FIG.

  Therefore, the input port 1502 and the output port 1504 are in communication with each other, and the second port 1604 and the drain port 1612 are in a disconnected state, so that the hydraulic actuator (1) 550 has a line pressure as shown in FIG. PL is supplied via the shift control valve (1) 1500. With the supply of the line pressure PL, the hydraulic pressure in the hydraulic actuator (1) 550 is increased, and the groove width of the primary pulley 500 is narrowed. As a result, the wrapping radius of the belt 700 in the primary pulley 500 increases and the gear ratio decreases (changes to the speed increasing side), that is, the continuously variable transmission 350 is upshifted.

  Note that the shift FB control unit 1408 may execute shift FB control when the stop determination flag is off and the extremely low vehicle speed determination flag is off, for example.

  The closing control unit 1410 performs closing control when the vehicle is stopped or when the vehicle is traveling at an extremely low vehicle speed and the speed ratio is not the maximum speed ratio.

  Specifically, the closing control unit 1410 sets the duty values output to the DS (1) 1200 and the DS (2) 1210 to 0%. As a result, the spool 1508 in the shift control valve (1) 1500 and the spool 1608 in the shift control valve (2) 1600 are both in the state on the left side of FIG.

  Therefore, the input port 1502 and the output port 1504 are cut off, and the second port 1604 and the drain port 1612 are cut off, so that the hydraulic actuator (1) 550 has a line pressure as shown in FIG. PL is supplied via the pressure regulating valve 1700 and the shift control valve (2) 1600. The line pressure PL is adjusted to a hydraulic pressure reduced by an amount corresponding to the elastic force of the spring 1702 by the pressure adjusting valve 1700 and supplied to the hydraulic actuator (1) 550. The pressure regulating valve 1700 regulates the line pressure PL to a hydraulic pressure that can secure at least a hydraulic pressure dropout due to hydraulic oil leakage from the hydraulic actuator (1) 550 in the hydraulic actuator (1) 550. Note that the elastic force of the spring 1702 is adapted in advance through experiments or the like. By executing the closing control, the hydraulic actuator (1) 550 is prevented from being released.

  In the continuously variable transmission 350, the speed change for changing the winding position of the belt 700 around the primary pulley 500 and the secondary pulley 600 is executed in a state where the pulleys 500 and 600 are rotating and the belt 700 is running. When the pulleys 500 and 600 and the belt 700 are stopped, the winding position of the belt 700 cannot be changed without shifting the belt 700, that is, the gear cannot be changed. Therefore, in the continuously variable transmission 350 mounted on the vehicle, when the vehicle suddenly stops, the continuously variable transmission 350 stops due to the stop of the vehicle. The continuously variable transmission 350 stops before changing to the belt 700 winding state that sets the normally set speed reduction ratio, and remains smaller than the speed ratio set at the start. Sometimes. The so-called belt return is in a poor state.

  In this way, when the vehicle starts with a bad belt return and performs feedback control of the transmission ratio, since the transmission ratio to be set is the maximum deceleration state, the transmission ( Downshift) occurs. In the continuously variable transmission 350 having the above-described configuration, this is executed by abruptly increasing the groove width of the primary pulley 500. Therefore, the belt 700 is loosened, which causes the belt 700 and the pulleys 500, 600. There is a possibility of slipping between the two.

  Therefore, when the vehicle is stopped or when the vehicle is traveling at an extremely low speed and the transmission gear ratio is not the maximum transmission gear ratio, the groove width in the primary pulley is suddenly increased by performing the closing control (that is, The belt 700 is prevented from slipping due to being downshifted.

  Note that, since the pressure is regulated from the pressure regulating valve 1700 by the closing control so that the oil pressure is surely suppressed, the gear ratio changes to the speed increasing side when the closing control is continuously executed. Go up, that is, upshift.

  Further, the closing control unit 1410 controls the closing when, for example, the stop determination flag is on, or when the extremely low vehicle speed determination flag is on and the speed ratio determination flag is off. May be executed.

  The duty down control unit 1412 is used when the vehicle is not stopped, the vehicle is traveling at an extremely low vehicle speed, the gear ratio is the maximum gear ratio, and not at the first start after the engine is started. Execute duty down control.

  Specifically, the duty-down control unit 1412 reduces the signal pressure applied from the DS (1) 1200 to the signal pressure port 1506 by setting the duty value output to the DS (1) 1200 to 0%. Then, the spool 1508 is in the left side state.

  Further, the duty down control unit 1412 sets the duty value output to the DS (2) 1210 to 100%, thereby increasing the signal pressure applied from the DS (2) 1210 to the signal pressure port 1606, and the spool 1608. Is the state on the right side of FIG.

  Therefore, the input port 1502 and the output port 1504 are cut off, and the second port and the drain port 1612 are in communication with each other, so that the hydraulic oil in the hydraulic actuator (1) 550 is as shown in FIG. The shift control valve (2) 1600 is discharged from the second port 1604 via the drain port 1612. Therefore, the hydraulic pressure of the hydraulic actuator (1) 550 decreases. As the hydraulic pressure of the hydraulic actuator (1) 550 decreases, the groove width of the primary pulley 500 increases, so that the wrapping radius of the belt 700 in the primary pulley 500 decreases and the shift increases (changes to the deceleration side). Downshift will occur.

  Note that the duty-down control unit 1412 has, for example, the stop determination flag is off, the extremely low vehicle speed determination flag is on, the transmission ratio determination flag is on, and the start determination flag is off. In this case, the duty down control may be executed.

  The slow duty down control unit 1414 is when the vehicle is not stopped, the vehicle is traveling at an extremely low vehicle speed, the transmission gear ratio is the maximum, and the first start after the engine is started. In this case, the slow duty down control is executed.

  Specifically, the slow duty down control unit 1414 sets the signal value applied from the DS (1) 1200 to the signal pressure port 1506 by setting the duty value output to the DS (1) 1200 to 0%. The spool 1508 falls to the left side.

  Further, the gradual duty down control unit 1414 sets the duty value output to the DS (2) 1210 to a predetermined value A between 0% and 100%, so that the signal from the DS (2) 1210 is transmitted. The force that pushes up the spool 1608 based on the signal pressure applied to the pressure port 1606 in FIG. 2 and the elastic force generated when the spring 1610 contracts as the spool 1608 is pushed up balances the protrusion 1616 in FIG. It becomes the position of the broken line.

  Therefore, the input port 1502 and the output port 1504 are cut off, the first port 1602 and the second port 1604 are in communication, and the second port 1604 and drain port 1612 are in communication.

  Therefore, as shown in FIG. 7, the line pressure PL is supplied to the hydraulic actuator (1) 550 via the pressure regulating valve 1700 and the shift control valve (2) 1600. The line pressure PL is adjusted to a hydraulic pressure reduced by an amount corresponding to the elastic force of the spring 1702 by the pressure adjusting valve 1700 and supplied to the hydraulic actuator (1) 550.

  Further, as shown in FIG. 7, the hydraulic oil in the hydraulic actuator (1) 550 is discharged from the second port 1604 of the transmission control valve (2) 1600 via the drain port 1612. Therefore, in the hydraulic actuator (1) 550, the supply of the hydraulic oil via the oil passage (2) and the discharge of the hydraulic oil via the oil passage (3) are performed in parallel.

  The predetermined value A indicates the flow rate of the hydraulic oil in the oil passage (2) and the flow rate of the hydraulic oil in the oil passage (3) in the transition state in which both the oil passage (2) and the oil passage (3) are in communication. Are values that are set so that both the shifting to the speed increasing side of the continuously variable transmission 350 and the slipping of the belt 700 are suppressed, and are adapted by experiments or the like.

  Further, in the present embodiment, the stop determination unit 1400, the extremely low speed travel determination unit 1402, the transmission ratio determination unit 1404, the start determination unit 1406, the transmission FB control unit 1408, the closing control unit 1410, the duty Both the down control unit 1412 and the slow duty down control unit 1414 will be described as functioning as software realized by the CPU of the ECU 1000 executing a program stored in the memory 1002. It may be realized. Such a program is recorded on a storage medium.

  With reference to FIG. 8, a control structure of a program executed by ECU 1000 of the continuously variable transmission according to the present embodiment will be described.

  In step (hereinafter, step is referred to as S) 100, ECU 1000 determines whether or not the vehicle is stopped. If the vehicle is stopped (YES in S100), the process proceeds to S108. If not (NO in S100), the process proceeds to S102.

  In S102, ECU 1000 determines whether or not the vehicle is traveling at an extremely low vehicle speed. If the vehicle is traveling at an extremely low vehicle speed (YES in S102), the process proceeds to S104. If not (NO in S102), the process proceeds to S114.

  In S104, ECU 1000 determines whether or not the gear ratio is the maximum gear ratio. If the gear ratio is the maximum gear ratio (YES in S104), the process proceeds to S106. If not (NO in S104), the process proceeds to S108.

  In S106, ECU 1000 determines whether or not it is the first start after engine 100 is started. If it is during the first start after engine 100 is started (YES in S106), the process proceeds to S112. If not (NO in S106), the process proceeds to S110.

  In S108, ECU 1000 executes the closing control. In S110, ECU 1000 executes duty down control. In S112, ECU 1000 executes a slow duty down control. In S114, ECU 1000 executes shift FB control.

  The operation of the continuously variable transmission according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG.

  For example, when the vehicle is stopped (YES in S100), or the vehicle is traveling at a very low speed (NO in S100, YES in S102), and the gear ratio is not the maximum gear ratio. If so (NO in S104), the closing control is executed (S108).

  Therefore, the hydraulic actuator (1) 550 is supplied with the hydraulic pressure in which the line pressure PL is regulated by the regulating valve 1700. At this time, the duty value in DS (2) is 0%. Therefore, as shown in FIG. 9, the hydraulic pressure in the hydraulic actuator (1) 550 is Pin (1) when the closing control is executed. Pin (1) is regulated by a pressure regulating valve 1700 so as to have a hydraulic pressure at which slipping of the belt 700 is reliably suppressed. Pin (1) is an area in which the continuously variable transmission 350 is upshifted when the vehicle starts to travel. Therefore, Pin (1) is increased particularly when the confinement control is continuously executed while the vehicle is traveling. Will shift.

  If the vehicle is not stopped (NO in S100) and is not running at an extremely low speed (NO in S102), that is, if the vehicle speed is greater than a predetermined speed Va, the shift FB control is executed ( S114). Therefore, duty values corresponding to the target rotation speed of the primary pulley rotation speed are output to DS (1) 1200 and DS (2) 1210, respectively, and continuously variable transmission 350 shifts according to the traveling state of the vehicle.

  The vehicle is not stopped (NO in S100), is running at a very low speed (YES in S102), the gear ratio is the maximum gear ratio (YES in S106), and engine 100 is started. If it is not at the time of the next first start (NO in S106), duty down control is executed (S110).

  Therefore, the hydraulic oil in the hydraulic actuator (1) 550 is discharged via the second port 1604 and the drain port 1612, and the hydraulic pressure of the hydraulic actuator (1) 550 decreases. Therefore, the maximum gear ratio of the continuously variable transmission 350 is maintained.

  At this time, the duty value output to DS (2) is 100%. Therefore, as shown in FIG. 9, the hydraulic pressure in the hydraulic actuator (1) 550 is zero when the duty down control is executed. That is, the hydraulic pressure in the hydraulic actuator (1) 550 is an area where belt slip occurs when the speed ratio is not maximum.

  Further, the vehicle is not stopped (NO in S100), is running at an extremely low speed (YES in S102), the transmission gear ratio is the maximum transmission gear ratio (YES in S106), and engine 100 When the vehicle is starting for the first time after starting (YES in S106), a slow duty down control is executed (S112).

  For this reason, the hydraulic actuator (1) 550 is supplied with the hydraulic pressure in which the line pressure PL is regulated by the pressure regulating valve 1700 via the transmission control valve (2) 1600, while the hydraulic oil in the hydraulic actuator (1) is supplied. It is discharged via the second port 1604 and the drain port 1612.

  At this time, the duty value output to DS (2) 1210 is A%. Therefore, as shown in FIG. 9, the hydraulic pressure in the hydraulic actuator (1) 550 is Pin (2) during the execution of the slow duty down control. Pin (2) suppresses upshifting when the vehicle is traveling at an extremely low vehicle speed, and suppresses belt slippage when the hydraulic pressure in the hydraulic actuator (1) 550 is not the maximum. It is an area to do.

  As described above, according to the continuously variable transmission according to the present embodiment, the vehicle speed is equal to or lower than the predetermined speed Va, the speed ratio is the maximum, and the engine is started. In the case of the first start at a later time, by continuing the transition state, the supply of hydraulic oil to the hydraulic actuator (1) via the pressure regulating valve is continued, and the hydraulic oil is discharged from the hydraulic actuator (1). Will be. Therefore, by controlling the flow rate of the hydraulic oil in the second and third oil passages so as to suppress the shift to the speed increasing side of the continuously variable transmission and the slip of the belt, the hydraulic oil to the hydraulic actuator (1) is controlled. It is possible to achieve a balance between the supply amount and the hydraulic oil discharge amount from the hydraulic actuator (1). Therefore, the working hydraulic pressure in the hydraulic actuator (1) can be made constant. By making the hydraulic pressure of the hydraulic actuator (1) constant, it is possible to continuously generate hydraulic pressure that can achieve both suppression of upshifting and suppression of belt slip. Therefore, it is possible to suppress the occurrence of belt slip while suppressing an unnecessary upshift.

  In particular, since the fluctuation of the hydraulic pressure is suppressed by performing the control that continues the transition state while the vehicle is in the extremely low vehicle speed region, it is possible to avoid the influence caused by the response delay of the hydraulic pressure. Furthermore, since the vehicle may move due to a disturbance while the engine is stopped and the detection accuracy of the gear ratio may deteriorate, by performing control to continue the transition state at the first start after the engine is started, Generation | occurrence | production can be suppressed reliably.

  Therefore, it is possible to provide a continuously variable transmission that achieves both suppression of unnecessary upshifting and suppression of belt slippage in an extremely low vehicle speed region.

  Further, when the vehicle is in a stopped state, or when the vehicle speed is equal to or lower than a predetermined speed Va and the speed ratio is not the maximum speed ratio, the oil passage (1) is shut off, In addition, by bringing the oil passage (3) into a communicating state, the line pressure PL is supplied to the hydraulic actuator (1) via the pressure regulating valve. Therefore, the hydraulic pressure that suppresses belt slip in the hydraulic actuator (1) can be secured. In addition, when the start is not the first time after the engine is started and the detected gear ratio is the maximum gear ratio, it can be said that the belt has moved to a position corresponding to the start. Therefore, when the speed of the vehicle is equal to or lower than a predetermined speed Va, the maximum speed ratio is maintained by setting the oil passage (1) to the shut-off state and the oil passage (2) to the communication state. be able to. Therefore, it is possible to suppress a decrease in driving force.

  In the present embodiment, the ECU is the first start after the engine is started, the vehicle is not stopped, is traveling at an extremely low speed, the speed ratio is the maximum, and the engine is started. In this case, it has been described that a predetermined value A is output as a duty value for DS (2). However, the present invention is not limited to outputting a predetermined value.

  For example, ECU 1000 may change the duty value output to DS (2) 1210 during the slow duty down control according to the temperature of the hydraulic oil detected by oil temperature sensor 444.

  ECU 1000 is a case where the flow rate of the hydraulic oil in the oil passage (2) when the temperature of the hydraulic oil detected by the oil temperature sensor 444 is the first temperature is a second temperature higher than the first temperature. The shift control valve (2) 1600 may be controlled so as to be smaller than the flow rate of hydraulic oil in the oil passage (2). If it does in this way, the flow volume of the hydraulic fluid in an oil path (2) can be made into the flow volume corresponding to characteristics, such as a viscosity with respect to the temperature of hydraulic fluid. Therefore, the balance between the supply amount and discharge amount of the hydraulic oil in the actuator can be achieved with high accuracy.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram of a continuously variable transmission. It is a figure which shows a part of hydraulic circuit for the transmission control of a continuously variable transmission. It is a figure which shows the flow path of the hydraulic fluid at the time of duty up control. It is a figure which shows the flow path of the hydraulic fluid at the time of transmission feedback control. It is a figure which shows the flow path of the hydraulic oil at the time of closing control. It is a figure which shows the flow path of the hydraulic fluid at the time of duty down control. It is a figure which shows the flow path of the hydraulic fluid at the time of moderate duty down control. It is a flowchart which shows the control structure of the program performed by ECU of the continuously variable transmission which concerns on this Embodiment. It is a figure which shows the relationship between a primary pulley pressure and the duty value of DS (2).

Explanation of symbols

  100 engine, 200 torque converter, 210 lock-up clutch, 220 pump impeller, 230 turbine impeller, 240 stator, 250 one-way clutch, 260 oil pump, 290 forward / reverse switching device, 300 belt type continuously variable transmission mechanism, 350 continuously variable Transmission, 400 Turbine speed sensor, 410 Primary pulley speed sensor, 420 Secondary pulley speed sensor, 432 Engine speed sensor, 440 Wheel speed sensor, 442 Accelerator position sensor, 444 Oil temperature sensor, 500, 600 Pulley, 502 Primary shaft, 600 secondary pulley, 602 secondary shaft, 700 belt, 800 differential gear, 1002 memory, 1100 hydraulic control unit, 1110 speed change Degree control unit, 1120 belt clamping pressure control unit, 1130 line pressure control unit, 1132 lock-up engagement pressure control unit, 1140 clutch pressure control unit, 1150 manual valve, 1200, 1210 shift control duty solenoid, 1220 belt clamping pressure control Linear solenoid for control, 1230 Linear solenoid for line pressure control, 1240 Duty solenoid for lockup engagement pressure control, 1300 Oil passage, 1400 Stop determination unit, 1402 Extremely low speed travel determination unit, 1404 Gear ratio determination unit, 1406 Start determination unit, 1408 control unit, 1410 control unit, 1412 duty down control unit, 1414 slow duty down control unit, 1502, 1706 input port, 1504, 1708 output port, 1506, 1512, 1606, 1614 Pressure port, 1508,1608 spool, 1510,1610,1702 spring, 1602 first port, 1604 a second port, 1612 a drain port, 1616 projections, 1700 regulating valve, 1704 piston, 1710 orifices.

Claims (8)

A continuously variable transmission mounted on a vehicle having at least an engine as a drive source;
A driving pulley,
A driven pulley,
A belt wound around the driving pulley and the driven pulley;
An actuator for changing the groove width of the driving pulley by hydraulic pressure;
A hydraulic pressure source for generating the hydraulic pressure;
Speed detecting means for detecting the speed of the vehicle;
Gear ratio detecting means for detecting a gear ratio of the continuously variable transmission;
Adjusting means for adjusting at least one of the amount of hydraulic oil supplied to the actuator and the amount of hydraulic oil discharged from the actuator;
The first condition is satisfied when the vehicle is in a stopped state or when the speed of the vehicle is equal to or lower than a predetermined speed and the speed ratio is not a speed ratio corresponding to the start of the vehicle. The first means for controlling the adjusting means to stop the discharge of the hydraulic oil from the actuator and to maintain a supply amount at which the first hydraulic pressure at which the belt does not slip is maintained. Control means,
The detected vehicle speed is equal to or lower than a predetermined speed, the detected gear ratio is a gear ratio corresponding to the start of the vehicle, and the first start after the engine is started When the second condition is satisfied, the adjustment means for controlling the adjustment means so that the supply amount and the discharge amount are maintained at the second operation oil pressure lower than the first operation oil pressure. And a continuously variable transmission. The adjusting means includes
A first switching valve that switches a first oil passage connecting the hydraulic power source and the actuator from one of a communication state and a shut-off state to the other state;
A first state in which a second oil passage connecting the hydraulic oil discharge passage and the actuator is brought into communication, and a third oil passage connecting the hydraulic power source and the actuator is shut off; The second oil passage and the second oil passage and the second state in which the second oil passage is shut off and the third oil passage is in communication with the other state. A second switching valve that switches via a transition state in which all of the third oil passages are in a communication state;
A pressure regulating valve provided at a position between the hydraulic pressure source of the third oil passage and the second switching valve, and for regulating the hydraulic pressure supplied from the hydraulic pressure source to a predetermined hydraulic pressure;
The second control means sets the first and second switching valves so that when the second condition is satisfied, the first oil passage is shut off and the transition state continues. The continuously variable transmission according to claim 1, wherein the continuously variable transmission is controlled.   In the transition state, the second control means is configured so that the flow rate of the hydraulic oil in the second oil passage and the flow rate of the hydraulic oil in the third oil passage are shifted to the speed increasing side of the continuously variable transmission and The continuously variable transmission according to claim 2, wherein the second switching valve is controlled so as to have a flow rate at which any slip of the belt is suppressed.   When the first condition is satisfied, the first control means sets the first and second oil passages in a shut-off state and the third oil passage in a communicating state. The continuously variable transmission of Claim 2 or 3 which controls 2 switching valves. The continuously variable transmission is
A first control valve for controlling the switching operation of the first switching valve using hydraulic pressure;
A second control valve for controlling the switching operation of the second switching valve using hydraulic pressure,
The first and second control means control the first switching valve using the first control valve, and control the second switching valve using the second control valve. Item 5. The continuously variable transmission according to any one of Items 2 to 4.   In the continuously variable transmission, the detected vehicle speed is a predetermined speed or less, the detected gear ratio is a gear ratio corresponding to the start of the vehicle, and the engine When the third condition that it is not the first start after the start is established, the first and second oil passages are shut off and the second oil passage is communicated. The continuously variable transmission according to any one of claims 2 to 5, further comprising third control means for controlling the switching valve. The continuously variable transmission further includes oil temperature detecting means for detecting the temperature of the hydraulic oil,
The second control means is the actuator when the hydraulic pressure in the actuator is a second temperature higher than the first temperature when the detected temperature of the hydraulic oil is a first temperature. The continuously variable transmission according to any one of claims 1 to 6, wherein the adjusting means is controlled to be higher than a working hydraulic pressure inside.   The continuously variable transmission according to any one of claims 1 to 7, wherein the predetermined speed is a speed that cannot be detected with an accuracy greater than or equal to a predetermined degree by the speed detecting means.

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