JP2009275777A - Control device of continuously variable transmission and control method of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a continuously variable transmission and a control method of the continuously variable transmission wherein, in the case of slipping, shock on recovering grip after slipping is reduced. <P>SOLUTION: The control device of a continuously variable transmission is provided with a slip detection part for detecting slip of driving wheels (a vehicle wheel speed sensor 440, a G sensor 442) and a control part 1000 for, when slip of the driving wheels is detected by the detection part, changing a speed ratio to an acceleration side compared to a case in which slip is not detected. Preferably, the control device is provided with a vehicle body speed detection part (a vehicle wheel speed sensor 441) for detecting a vehicle body speed. When slip of the driving wheels is detected, the control part 1000 changes the speed change ratio so that the speed change ratio becomes closer to a target speed change ratio corresponding to the vehicle body speed detected by the vehicle body speed detection part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a continuously variable transmission and a control method for a continuously variable transmission, and more particularly to control when a drive wheel slips.

  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. The automatic transmission is configured to automatically switch the gear ratio (travel speed stage) based on, for example, the accelerator opening and the vehicle speed.

  The torque converter is convenient because it has a torque increasing action at the time of starting, but it causes some slipping during normal driving, resulting in poor fuel consumption. Therefore, the torque converter includes a lockup clutch that directly connects the input shaft and the output shaft during normal traveling.

Japanese Patent Laid-Open No. 2001-132828 (Patent Document 1) discloses that when a slip of a drive wheel is detected, the line pressure is increased and corrected, and the lockup clutch is released while maintaining the gear ratio immediately before the slip. Has been.
JP 2001-132828 A JP 2003-48462 A

  By the way, at the time of slip, there is no reaction force from the road surface, and the rotational speed of the drive wheels increases. If the gear ratio is constant, the engine speed also increases. If the grip recovers in this state, a shock due to the inertia torque of the engine may occur in the vehicle body.

  An object of the present invention is to provide a control device for a continuously variable transmission and a control method for the continuously variable transmission in which a shock at the time of grip recovery after the occurrence of slip is reduced.

  In summary, the present invention is a control device for a continuously variable transmission, in which a slip detection unit that detects slip of a drive wheel, and when the detection unit detects slip of a drive wheel, slip is detected. And a control unit that changes the gear ratio to the speed-increasing side as compared with the case where there is not.

  Preferably, the control device further includes a vehicle body speed detection unit that detects the vehicle body speed. The control unit includes a storage unit that stores a target gear ratio corresponding to the vehicle body speed. When the slip of the drive wheel is detected, the control unit changes the speed ratio so that the speed ratio approaches the target speed ratio corresponding to the vehicle speed detected by the vehicle speed detection unit.

  More preferably, the control unit does not change the gear ratio to the speed increasing side when the vehicle speed detected by the vehicle speed detecting unit is higher than the target speed ratio.

  More preferably, the storage unit further stores a shift map for determining a gear ratio based on the vehicle speed. The target gear ratio is a gear ratio that is on the highest speed side in the range of gear ratios that can be obtained on the gear map when the vehicle speed detected by the vehicle speed detector is the vehicle speed.

  More preferably, the target gear ratio is a gear ratio that is set when steady running is performed at the vehicle speed detected by the vehicle speed detector.

  Preferably, the continuously variable transmission is connected to the internal combustion engine by a torque converter with a lock-up clutch. When the slip of the drive wheel is detected, the control unit changes the engagement state of the lockup clutch to the release side.

  In another aspect, the present invention provides a control method for a continuously variable transmission, in which a slip is detected when a slip of the drive wheel is detected by the step of detecting the slip of the drive wheel and the detection unit. And a step of changing the gear ratio to the speed increasing side as compared with the case where the gear ratio is not set.

  Preferably, the vehicle on which the continuously variable transmission is mounted includes a vehicle body speed detection unit that detects the vehicle body speed and a storage unit that stores a target gear ratio corresponding to the vehicle body speed. The step of changing the speed ratio to the speed increasing side is to change the speed ratio so that the speed ratio becomes close to the target speed ratio corresponding to the vehicle speed detected by the vehicle speed detecting unit when the slip of the driving wheel is detected. To change.

  More preferably, the control method further includes a step of not changing the gear ratio to the speed increasing side when the vehicle speed detected by the vehicle speed detecting unit is higher than the target speed ratio.

  More preferably, the storage unit further stores a shift map for determining a gear ratio based on the vehicle speed. The target gear ratio is a gear ratio that is on the highest speed side in the range of gear ratios that can be obtained on the gear map when the vehicle speed detected by the vehicle speed detector is the vehicle speed.

  More preferably, the target gear ratio is a gear ratio that is set when steady running is performed at the vehicle speed detected by the vehicle speed detector.

  Preferably, the continuously variable transmission is connected to the internal combustion engine by a torque converter with a lock-up clutch. The control method further includes a step of changing the engagement state of the lockup clutch to the disengagement side when slipping of the drive wheel is detected.

  According to the present invention, when slip occurs, a shock at the time of grip recovery thereafter is reduced, and driving comfort is improved.

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

[Vehicle powertrain configuration]
FIG. 1 is a diagram showing a configuration of a power train of a vehicle according to the present embodiment.

  Referring to FIG. 1, the power train of this vehicle includes an engine 100, a torque converter 200, a forward / reverse switching device 290, a belt-type continuously variable transmission mechanism 300, a differential gear 800, a control unit 1000, a hydraulic pressure And a control unit 1100.

  The continuously variable transmission includes a torque converter 200, a forward / reverse switching device 290, a belt-type continuously variable transmission mechanism 300, 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, the output shaft rotational speed Ne (engine rotational speed Ne) of the engine 100 detected by the engine rotational speed sensor 430 and the input shaft rotational speed (pump rotational speed) of the torque converter 200 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. And a stator 240 for amplification. Torque converter 200 and belt type continuously variable transmission mechanism 300 are connected by a rotating shaft. The output shaft rotation speed Nt (turbine rotation speed Nt) of the torque converter 200 is detected by the turbine rotation 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 when the pump impeller 220 on the input shaft side rotates. The oil pump 260 supplies hydraulic pressure to various solenoids of the hydraulic control unit 1100.

  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 an input-side primary pulley 500, an output-side secondary pulley 600, and a metal belt 700 wound around the primary pulley 500 and the secondary pulley 600.

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

  Hydraulic oil is supplied to and discharged from hydraulic actuators (both not shown) of the primary pulley 500 and the secondary pulley 600, respectively. 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 controls the hydraulic pressure supplied to the hydraulic actuator of the primary pulley 500 so that the transmission gear ratio becomes a gear ratio that matches the rotational speed of the primary pulley 500 with the target rotational speed. Further, the hydraulic control unit 1100 is supplied to the hydraulic actuator of the secondary pulley 600 so as to obtain a tension necessary for transmitting the torque by pressing the movable sheave of the secondary pulley 600 toward the fixed sheave to sandwich the belt. Control the hydraulic pressure.

  The rotation speed NIN of the primary pulley 500 of the belt type continuously variable transmission mechanism 300 is detected by the primary pulley rotation speed sensor 410, and the rotation speed NOUT of the secondary pulley 600 is detected by the secondary pulley rotation speed sensor 420.

  These rotational speed sensors are provided to face the rotation detection gear teeth 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 detect slight rotations of the primary pulley 500 as an input shaft and the secondary pulley 600 as 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. The planetary gear has a sun gear connected to the input shaft, a carrier supporting the first and second pinions connected to the primary fixed sheave, and a reverse brake B1 in which the ring gear serves as a reverse friction engagement element. The input clutch C1 is interposed between the carrier and the ring gear. The input clutch C1 is also referred to as a forward clutch or a forward clutch, and the position of the shift lever detected by the shift position sensor 448 is a position other than the parking (P) position, reverse (R) position, and neutral (N) position. Thus, the vehicle is used in an engaged state at a forward position where the vehicle moves forward.

  The control unit 1000 and the hydraulic control unit 1100 that control these power trains will be described. The control unit 1000 is realized by an ECU (electronic control unit). Control unit 1000 may be realized by a single ECU, or may be realized by a plurality of ECUs.

  The controller 1000 receives a signal representing the turbine rotational speed Nt from the turbine rotational speed sensor 400, a signal representing the primary pulley rotational speed NIN from the primary pulley rotational speed sensor 410, and a secondary pulley rotational speed NOUT from the secondary pulley rotational speed sensor 420. A signal representing is input.

  The hydraulic control unit 1100 includes a shift 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. The control unit 1000 includes a shift control duty solenoid 1200 of the hydraulic control unit 1100, a shift control duty solenoid 1210, a belt clamping pressure control linear solenoid 1220, a line pressure control linear solenoid 1230, and a lockup engagement pressure. A control signal is output to the control duty solenoid 1240.

  The shift speed control unit 1110 controls the shift speed on the acceleration side by controlling the amount of hydraulic oil flowing into the hydraulic actuator of the primary pulley 500 in accordance with the output hydraulic pressure of the shift control duty solenoid 1200. Further, the shift speed control unit 1110 controls the shift speed on the deceleration side by controlling the outflow amount of hydraulic oil from the hydraulic actuator of the primary pulley 500 according to the output hydraulic pressure of the shift control duty solenoid 1210. Control unit 1000 controls shift control duty solenoids 1200 and 1210 according to the wheel speed and the accelerator opening. Shift control is performed by controlling the inflow and outflow of hydraulic oil to the hydraulic actuator 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 of the secondary pulley 600 by the output hydraulic pressure of the belt clamping pressure control linear solenoid 1220 that changes according to the input shaft torque of the primary pulley 500 and the gear ratio. Thus, the belt clamping pressure is controlled. The input shaft torque may be estimated from, for example, the output torque of the engine 100 based on the rotational speed of the engine 100, the intake air amount, and the like, and the torque ratio in the torque converter 200, or may be directly detected.

  The line pressure control unit 1130 controls the line pressure according to the output hydraulic pressure of the line pressure control linear solenoid 1230. The hydraulic pressure of the actuator of the primary pulley 500 is estimated based on the inflow amount and the outflow amount of hydraulic oil to the hydraulic actuator of the primary pulley 500. Here, the line pressure is a hydraulic pressure obtained by adjusting the hydraulic pressure supplied by the oil pump 260 by a regulator valve (not shown).

  The lockup engagement pressure control unit 1132 switches between engagement and disengagement of the lockup clutch 210 and gradually increases and decreases the engagement pressure of the lockup clutch 210 by the output hydraulic pressure of the lockup engagement pressure control duty solenoid 1240. To control.

  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 supplies the manual valve with 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.

  The control unit 1000 further includes a signal Acc indicating the opening degree of the accelerator pedaled by the driver from the accelerator position sensor 444, a signal indicating the opening degree of the electromagnetic throttle from the throttle position sensor (not shown), and the engine speed. A signal indicating the rotational speed (Ne) of the engine 100 from the sensor 430, a signal indicating whether or not the vehicle is in the forward travel position from the shift position sensor 448, and a signal indicating whether or not the foot brake is in an operating state from the foot brake switch 446. , Respectively.

  Wheel speed sensor 440 detects the rotational speed of a driving wheel (not shown) to which driving force is transmitted by differential gear 800. The wheel speed sensor 440 transmits a wheel speed signal indicating the detected rotation speed of the driving wheel to the control unit 1000. If the vehicle speed can be detected, the present invention is not particularly limited to detecting the rotational speed of the wheel. For example, the vehicle speed is calculated based on the secondary pulley rotational speed and the reduction ratio from the continuously variable transmission to the drive wheels. You may do it.

  Wheel speed sensor 441 detects the rotational speed of a driven wheel (not shown) to which the driving force from engine 100 is not transmitted. The wheel speed sensor 441 transmits a wheel speed signal indicating the detected rotational speed of the driven wheel to the control unit 1000.

  The G sensor 442 is an acceleration sensor attached to the vehicle. For example, it is possible to detect uphill or the like and use it for control that does not perform neutral control on the uphill.

  The control unit 1000 can detect the slip of the driving wheel by comparing the outputs of the wheel speed sensors 440 and 441 or by comparing the output of the wheel speed sensor 440 and the output of the G sensor 442.

FIG. 2 is an example of a shift diagram of the belt type continuously variable transmission mechanism 300.
Referring to FIG. 2, the horizontal axis indicates the vehicle speed proportional to the rotational speed NOUT of the output shaft of continuously variable transmission mechanism 300, and the vertical axis indicates the rotational speed NIN of the input shaft of continuously variable transmission mechanism 300. ing. The rotational speed NIN is substantially equal to the engine rotational speed Ne when the torque converter lock-up clutch is engaged.

  The gear ratio γ is a ratio of the input rotational speed NIN to the vehicle speed V1, and is represented by a slope of a straight line passing through the origin in FIG. The gear ratio corresponding to the low gear has a large straight line slope, and the gear ratio corresponding to the high gear has a small straight line slope.

  Shift lines are determined in advance for a plurality of accelerator openings such as an accelerator opening Acc of 0, 10, 20, 50, 70%. The shift map shown in FIG. 2 is stored in the memory 1010. Then, the vehicle speed and the accelerator opening are detected by the sensor, and the control unit 1000 controls the shift speed control unit 1110 in the hydraulic control unit 1100 based on the map in the memory 1010 so that the speed ratio γ is realized. Take control.

  FIG. 3 is a diagram illustrating a study example for explaining the movement of the operating point on the shift diagram when a slip occurs.

  Referring to FIG. 3, belt type continuously variable transmission mechanism 300 can change the speed ratio between speed ratios γmin to γmax. When the accelerator opening Acc = α1 and the vehicle is traveling at the vehicle speed V1, the operating point is P1.

  In this state, it is assumed that slip occurs on the drive wheels due to road surface unevenness. Then, although the speed at which the vehicle body moves (hereinafter referred to as the vehicle speed) remains at the speed V1, the vehicle speed obtained from the rotational speed of the drive wheels and the rotational speed (NOUT) of the output shaft apparently increases to V2. Then, the operating point moves to the operating point P2. The gear ratio also changes to a value corresponding to the slope connecting the origin and the operating point P2 accordingly.

  Since the slip has occurred, the driver returns the accelerator pedal and the accelerator opening Acc = 0. However, since this change is abrupt, the belt-type continuously variable transmission mechanism 300 recovers the tire grip while not changing the gear ratio. The operating point at this time is P3B. Thereafter, the gear ratio is changed so that the operating point is directed toward the operating point P4 determined by the accelerator opening Acc = 0 and the vehicle speed V1.

  Here, the movement from the occurrence of the slip at the operating point P2 to the grip recovery at the operating point P3B occurs in a very short time. If the change amount ΔNB of the engine rotation speed Ne at this time is large, a shock due to inertia of the engine rotation is transmitted to the vehicle body. If the change amount ΔNB can be controlled to be small, there is an effect of reducing the shock generated in the vehicle body.

[Embodiment 1]
FIG. 4 is a flowchart for illustrating control executed by control unit 1000 of FIG. 1 in Embodiment 1 when slip occurs. The process of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  FIG. 5 is a diagram showing the movement of the operating point on the shift diagram when a slip occurs when the control of the flowchart of FIG. 4 is executed.

  4 and 5, first, when the process is started, control unit 1000 in FIG. 1 determines whether or not the drive wheels are slipping in step S <b> 1. The determination of slip is made when the difference between the detected value of the wheel speed sensor 440 that detects the rotational speed of the driving wheel and the detected value of the wheel speed sensor 441 that detects the rotational speed of the driven wheel is equal to or greater than a predetermined value. be able to. In addition, the determination of slip is made by observing a change in the detection value of the wheel speed sensor 440 and detecting that the acceleration becomes a value that cannot be in a non-slip state, or based on the detection value of the wheel speed sensor 440. The acceleration calculated in this way may be compared with the detection value of the G sensor 442.

  If no slip of the drive wheel is detected in step S1, the operating point on the shift diagram remains at P1, for example. In this case, the process proceeds from step S1 to step S5, and control is transferred to the main routine.

  If slip of the drive wheel is detected in step S1, the operating point on the shift map moves from P1 to P2, for example. In this case, the process proceeds from step S1 to step S2.

  In step S2, control unit 1000 calculates a lower limit value of the gear ratio that can be set from the vehicle body speed of the vehicle and the shift line map. Here, in FIG. 5, the vehicle speed is V1, which can be obtained from the output of the wheel speed sensor 441 of the driven wheel. At this time, the intersection P4 between the shift line of the accelerator opening Acc = 0 and the line of the vehicle speed V1 is an operating point that gives the lower limit value γ2 of the speed ratio that can be set by the vehicle speed.

  In step S3, it is determined whether or not the current speed ratio (the speed ratio γ1 because it is the operating point P2) is larger than the lower limit value γ2 (low side). If the gear ratio> lower limit value is not satisfied, the process proceeds from step S3 to step S5, and the control is moved to the main routine. However, at the time of slip, in most cases, gear ratio> lower limit value is established. In that case, the process proceeds from step S3 to step S4.

  In step S4, control unit 1000 controls transmission speed control unit 1110 of the hydraulic control unit so as to set the transmission ratio to the lower limit value. In the case of the operating point P2 shown in FIG. 5, since the speed ratio is changed from the current speed ratio γ1 to the lower limit speed ratio γ2, the operating point moves from P2 to P3A. When the process of step S4 ends, the process proceeds to step S5, and control is transferred to the main routine.

  Thereafter, the operating point in FIG. 5 moves from P3A (slip state) to P4 (grip state). The amount of change ΔNA in the rotational speed at this time affects the shock during gripping. Compared with the change amount ΔNB in the case of FIG. 3, the engine rotation speed is lowered by changing the gear ratio during the slip, so the change amount ΔNA becomes smaller and the shock is improved.

  That is, in the case of FIG. 3, since the gear ratio was maintained at γ1 during the slip, the operating point basically changed from the point P2 to P3B along the line of the gear ratio γ1 during gripping. In contrast, in the case of FIG. 5, the gear ratio is changed from γ1 to γ2 during the slip and the operating point is changed from the point P2 to the point P3A, so the operating point changes from the point P3A to the point P4 during gripping. To do. Therefore, the change in the engine rotation speed during gripping is reduced from ΔNB to ΔNA, and the shock during gripping due to engine inertia is improved.

FIG. 6 is a diagram specifically illustrating an example of a change in the gear ratio.
Referring to FIG. 6, it is assumed that at the operating point P1, the engine rotation speed is 4000 rpm, the vehicle speed calculated based on the rotation speed of the drive wheels is 40 km / h, and the gear ratio is γ = 2.0.

  At the operating point P2 where the slip has occurred, the engine rotational speed is 5000 rpm, the vehicle speed calculated based on the rotational speed of the drive wheels is 60 km / h, and the gear ratio is changed to γ = 1.67.

  Here, if the gear ratio is not changed toward the lower limit value, the engine speed is 3000 rpm and the vehicle speed is 40 km / h at the operating point P3B at the time of gripping. Slightly smaller than .67. Here, the change amount of the engine rotation speed when the operating point P2 is changed to P3B is ΔNB = 2000 rpm. Since the driver has released the accelerator pedal, the operating point thereafter moves to a point P4 where the lower limit gear ratio γ = 0.5.

  When the control according to the present embodiment is performed, the gear ratio is changed to γ = 0.5 which is the lower limit value at the vehicle speed of 40 km / h during the slip at the operating point P2, so that the operating point moves to P3A. At the operating point P3A, the engine speed is 1500 rpm, the vehicle speed is 60 km / h, and the gear ratio is γ = 0.5. When gripping, the operating point moves from the point P3A to P4. The operating point P4 is an engine speed of 1000 rpm, a vehicle speed of 40 km / h, and a gear ratio γ = 0.5. Here, the amount of change in the engine rotation speed when the operating point P3A is changed to P4 is ΔNA = 500 rpm.

FIG. 7 is an operation waveform diagram for explaining the operation at the time of slip.
Referring to FIG. 7, it is assumed that the accelerator opening is increased at time t1, and the occurrence of slip is started at time t2. Then, although the vehicle body speed has not changed to 40 km / h, the wheel speed of the driving wheel starts to increase, and the vehicle body speed and the wheel speed deviate. From time t2 to t3, a shift based on the shift diagram is executed, and the gear ratio γ slightly decreases while the input rotation speed NIN of the transmission mechanism increases.

  At time t3 to t4, when the speed ratio γ is maintained as it is with a broken line, the input shaft rotation speed NIN is also maintained at a high state, and the rotation speed does not change when the grip is returned at time t4 after the accelerator opening decreases. The amount of change is ΔNB.

  When the control according to the present embodiment is executed, the speed ratio γ is lowered as shown by the solid line at time t3 to t4, and the input shaft rotational speed NIN is also lowered to some extent by time t4. Therefore, when the grip is returned at time t4, the amount of change in the rotational speed NIN can be ΔNA which is smaller than ΔNB.

Therefore, a shock caused by engine inertia during gripping is reduced.
[Embodiment 2]
In the second embodiment, in addition to the control of the first embodiment, when the lockup clutch is engaged when a slip occurs, the engagement is released.

  FIG. 8 is a flowchart for illustrating control executed by control unit 1000 in FIG. 1 in the second embodiment when a slip occurs.

  The control shown in FIG. 8 is different from the control of the first embodiment in that the processes of steps S11 and S12 are executed in addition to the control of the flowchart executed in the first embodiment described in FIG. Since the processing of other parts is described in FIG. 4, the description will not be repeated.

  When the process of setting the gear ratio to the lower limit value at the vehicle body speed is executed in step S4, the control unit 1000 determines in step S11 whether or not the lockup clutch 210 is in the ON state (engaged state). This determination is made based on, for example, the content of the control signal output to the lockup engagement pressure control duty solenoid 1240.

  If it is determined in step S11 that the lockup is not in the ON state, the process proceeds to step S5 and the control is moved to the main routine.

  On the other hand, if it is determined in step S11 that the lockup is in the ON state, the process proceeds to step S12, and the lockup state is released. That is, the control unit 1000 outputs a control signal so that the lockup clutch 210 is released to the lockup engagement pressure control duty solenoid 1240. Then, the process proceeds to step S5, and the control is moved to the main routine.

  In the second embodiment, the lock-up clutch is released when a slip occurs. In addition to the effect of reducing the shock at gripping by changing the gear ratio in the first embodiment, the change in the rotational speed at the torque converter is changed. The effect of further shock reduction of absorbing by the fluid is exhibited. Instead of completely releasing the lock-up clutch, it may be half-engaged in the slip state.

[Embodiment 3]
In the first and second embodiments, when the slip occurs, the speed ratio is changed to the lower limit of the speed ratio at the vehicle speed at that time, thereby reducing the amount of change in the engine speed and reducing the shock. However, the target value of the gear ratio to be changed when slip occurs does not necessarily have to be the lower limit value.

  FIG. 9 is a flowchart for illustrating control executed by control unit 1000 of FIG. 1 in Embodiment 3 when slip occurs.

  FIG. 10 is a diagram showing the movement of the operating point on the shift diagram when slip occurs when the control of the flowchart of FIG. 9 is executed.

  Referring to FIGS. 9 and 10, first, when the process is started, control unit 1000 in FIG. 1 determines whether or not the drive wheels are slipping in step S <b> 21. The determination of slip is made when the difference between the detected value of the wheel speed sensor 440 that detects the rotational speed of the driving wheel and the detected value of the wheel speed sensor 441 that detects the rotational speed of the driven wheel is equal to or greater than a predetermined value. be able to. In addition, the determination of slip is made by observing a change in the detection value of the wheel speed sensor 440 and detecting that the acceleration becomes a value that cannot be in a non-slip state, or based on the detection value of the wheel speed sensor 440. The acceleration calculated in this way may be compared with the detection value of the G sensor 442.

  If no slip of the driving wheel is detected in step S21, the operating point on the shift diagram of FIG. 10 remains, for example, P1. In this case, the process proceeds from step S21 to step S25, and control is transferred to the main routine.

  If slip of the drive wheel is detected in step S21, the operating point on the shift diagram of FIG. 10 moves from P1 to P2, for example. In this case, the process proceeds from step S21 to step S22.

  In step S22, the control unit 1000 obtains a gear ratio for steady running at the vehicle body speed of the vehicle from a predetermined map or the like.

FIG. 11 is a diagram illustrating an example of a map for determining a gear ratio during constant speed traveling.
As shown in FIG. 11, an optimum speed ratio γ is determined in the case where the vehicle runs at a constant speed for each vehicle type.

  Referring again to FIG. 9 and FIG. 10, it is assumed that the optimum gear ratio when traveling at a constant speed at the vehicle speed V1 is calculated to be γ3.

  Then, in step S23, it is determined whether or not the current gear ratio (the gear ratio γ1 because it is the operating point P2) is greater than γ3 (low side). If transmission ratio> calculated value is not satisfied, the process proceeds from step S23 to step S25, and the control is moved to the main routine. However, at the time of slip, in most cases, gear ratio> calculated value is established. In that case, the process proceeds from step S23 to step S24.

  In step S24, control unit 1000 controls shift speed control unit 1110 of the hydraulic control unit so as to set the transmission ratio to calculated value γ3. In the case of the operating point P2 shown in FIG. 10, since the speed ratio is changed from the current speed ratio γ1 to the calculated value γ3, the operating point moves from P2 to P3C. When the process of step S24 ends, the process proceeds to step S25, and control is transferred to the main routine.

  Thus, by setting the gear ratio to the optimum gear ratio for performing constant speed traveling at the vehicle speed at the time of slip occurrence, the control after grip recovery is more stable.

  Finally, the present embodiment will be generally described with reference to FIG. The control device for the continuously variable transmission detects a slip when the slip of the drive wheel is detected by the slip detector (wheel speed sensor 440, G sensor 442) that detects the slip of the drive wheel. Compared with the case where it is not, the control part 1000 which changes a gear ratio to the acceleration side is provided.

  Preferably, the control device further includes a vehicle body speed detection unit (wheel speed sensor 441) that detects the vehicle body speed. Control unit 1000 includes a storage unit (memory 1010) that stores a target gear ratio corresponding to the vehicle speed. When the slip of the drive wheel is detected, the control unit 1000 causes the transmission ratio to approach the target transmission ratio (γ2 in FIG. 5 and γ3 in FIG. 10) corresponding to the vehicle speed detected by the vehicle speed detection unit. Next, the gear ratio is changed.

  More preferably, control unit 1000 does not change the gear ratio to the speed increase side when the vehicle speed detected by the vehicle speed detection unit is higher than the target speed ratio.

  More preferably, the storage unit (memory 1010) further stores a shift map for determining a gear ratio based on the vehicle speed, for example, as shown in FIG. The target gear ratio is the highest speed side of the gear ratio range (between the operating point P1 and the operating point P4 in FIG. 5) that can be obtained on the speed map when the vehicle speed detected by the vehicle speed detector is the vehicle speed. (The speed ratio γ2 if the vehicle speed is V1 in FIG. 5).

  More preferably, the target gear ratio is a gear ratio that is set when steady running is performed at the vehicle speed detected by the vehicle speed detector, as shown in FIG. 11, for example.

  Preferably, the continuously variable transmission is connected to the internal combustion engine (engine 100) by a torque converter 200 with a lock-up clutch 210. When the slip of the drive wheel is detected, the control unit changes the engagement state of the lockup clutch 210 to the release side.

  In another aspect, the present invention is a method for controlling a continuously variable transmission, in which a slip is detected when the slip of the drive wheel is detected by step S1 of detecting the slip of the drive wheel and the detection unit. Compared with the case where it is not performed, step S4 which changes a gear ratio to the acceleration side is provided.

  Preferably, a vehicle equipped with a continuously variable transmission includes a vehicle body speed detection unit (wheel speed sensor 441) that detects a vehicle body speed and a storage unit (memory 1010) that stores a target gear ratio corresponding to the vehicle body speed. Including. In step S4 for changing the gear ratio to the speed increasing side, when slipping of the driving wheel is detected, the gear ratio is changed so as to approach the target gear ratio corresponding to the vehicle speed detected by the vehicle speed detecting unit. Change the ratio.

  More preferably, the control method further includes step S3 in which the gear ratio is not changed to the speed increasing side when the vehicle speed detected by the vehicle speed detecting unit is higher than the target speed ratio. .

  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 figure which shows the structure of the power train of the vehicle which concerns on this Embodiment. 4 is an example of a shift diagram of a belt type continuously variable transmission mechanism 300. FIG. It is a figure which shows the example of examination explaining the movement of the operating point on the shift map at the time of slip generation | occurrence | production. 3 is a flowchart for illustrating control executed by control unit 1000 of FIG. 1 in Embodiment 1 when slip occurs. FIG. 5 is a diagram illustrating movement of operating points on a shift diagram when slipping occurs when the control of the flowchart of FIG. 4 is executed. It is the figure which showed the example of the change of a gear ratio specifically. It is an operation | movement waveform diagram for demonstrating the operation | movement at the time of a slip. 6 is a flowchart for illustrating control executed by control unit 1000 of FIG. 1 in Embodiment 2 when a slip occurs. 10 is a flowchart for illustrating control executed by control unit 1000 of FIG. 1 in Embodiment 3 when slip occurs. FIG. 10 is a diagram illustrating movement of operating points on a shift diagram when slipping occurs when the control of the flowchart of FIG. 9 is executed. It is a figure which shows an example of the map for determining the gear ratio at the time of constant speed driving | running | working.

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, 400 turbine rotation Speed sensor, 410 Primary pulley rotation speed sensor, 420 Secondary pulley rotation speed sensor, 430 Engine rotation speed sensor, 440, 441 Wheel speed sensor, 442 G sensor, 444 Accelerator position sensor, 446 Foot brake switch, 448 Shift position sensor, 500 Primary pulley, 600 Secondary pulley, 700 belt, 800 differential gear, 1000 control unit, 1010 memory, 1100 hydraulic control , 1110 shift speed 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 duty control duty solenoid, 1220 Linear solenoid for belt clamping pressure control, 1230 linear solenoid for line pressure control, 1240 duty solenoid for control of lock-up engagement pressure, B1 reverse brake, C1 input clutch.

Claims (12)

A slip detector for detecting slip of the drive wheel;
A control of a continuously variable transmission, comprising: a control unit that changes a gear ratio to a speed increasing side when a slip of the drive wheel is detected by the detection unit as compared to a case where no slip is detected. apparatus. A vehicle speed detector for detecting the vehicle speed;
The control unit includes a storage unit that stores a target gear ratio corresponding to the vehicle speed,
When the slip of the driving wheel is detected, the control unit changes the speed ratio so that the speed ratio approaches the target speed ratio corresponding to the vehicle speed detected by the vehicle speed detection unit. The control device for a continuously variable transmission according to claim 1.   3. The control unit according to claim 2, wherein the control unit does not change the gear ratio to the speed increasing side when the vehicle speed detected by the vehicle speed detecting unit is higher than the target speed ratio. Control device for continuously variable transmission. The storage unit further stores a shift map for determining a gear ratio based on the vehicle speed,
The target speed ratio is a speed ratio that is on the highest speed side of a range of speed ratios that can be taken on the speed map when the vehicle speed detected by the vehicle speed detector is a vehicle speed. 4. The continuously variable transmission control device according to 3.   The control device for a continuously variable transmission according to claim 2 or 3, wherein the target gear ratio is a gear ratio set when steady running is performed at a vehicle speed detected by the vehicle speed detector. The continuously variable transmission is connected to the internal combustion engine by a torque converter with a lock-up clutch,
The control device for a continuously variable transmission according to claim 1, wherein when the slip of the drive wheel is detected, the control unit changes the engagement state of the lockup clutch to a disengagement side. Detecting slippage of the drive wheel;
A step of changing the transmission gear ratio to the speed-increasing side when the detection unit detects a slip of the drive wheel, compared to a case where no slip is detected, and a control method for a continuously variable transmission . Vehicles equipped with the continuously variable transmission are
A vehicle speed detector for detecting the vehicle speed;
A storage unit storing a target gear ratio corresponding to the vehicle speed,
The step of changing the transmission gear ratio to the speed increasing side brings the transmission gear ratio close to the target transmission gear ratio corresponding to the vehicle body speed detected by the vehicle body speed detection unit when slipping of the drive wheel is detected. As described above, the continuously variable transmission control method according to claim 7, wherein the speed ratio is changed.   9. The method according to claim 8, further comprising a step of not changing the gear ratio to the speed increasing side when the vehicle speed detected by the vehicle speed detecting unit is on the speed increasing side with respect to the target speed ratio. Control method for continuously variable transmission. The storage unit further stores a shift map for determining a gear ratio based on the vehicle speed,
9. The target gear ratio is a gear ratio that is on the highest speed side of a range of gear ratios that can be taken on the gearshift map when the vehicle speed detected by the vehicle speed detector is a vehicle speed. A control method for a continuously variable transmission according to claim 9.   10. The continuously variable transmission control method according to claim 8, wherein the target gear ratio is a gear ratio that is set when steady running is performed at a vehicle speed detected by the vehicle speed detector. 10. The continuously variable transmission is connected to the internal combustion engine by a torque converter with a lock-up clutch,
The control method is:
The continuously variable transmission control method according to any one of claims 7 to 11, further comprising a step of changing an engagement state of the lockup clutch to a disengagement side when slipping of the drive wheel is detected.

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