JP2008196581A - Transmission control device of belt-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent slippage of a belt in a range where the degree of return failure of the belt is large, and simultaneously to improve a transmission following property in a range where the degree of the return failure of the belt is small. <P>SOLUTION: The belt-type continuously variable transmission includes the belt 37 passing between a primary pulley 36 and a secondary pulley 37, and changes a transmission gear ratio by changing a pulley width of the primary pulley 36 for transmission by feed and discharge of operating oil to a hydraulic actuator 41. When an actual transmission gear ratio in starting deviates beyond a predetermined range to a speed increase side with respect to a target transmission gear ratio normally set in the starting, the transmission gear ratio is changed to a speed reduction side in the starting. At that time, in a range of a large degree of deviation in the starting, a discharge flow rate of the operating oil to the hydraulic actuator 41 is set to be small, and in a range of a small degree of deviation in the starting, the discharge flow rate of the operating oil to the hydraulic actuator 41 is set to be large. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling a shift in a belt type continuously variable transmission mounted on a vehicle such as an automobile.

  BACKGROUND ART Conventionally, a belt-type continuously variable transmission (CVT) is known as a transmission mounted on the output side of an automobile engine. This belt-type continuously variable transmission includes a primary shaft (drive side shaft) and a secondary shaft (driven side shaft) that are arranged in parallel to each other, and a primary pulley (drive side pulley) and a secondary shaft that are individually provided on each shaft. And a pulley (driven pulley).

  Both the primary pulley and the secondary pulley have a combination of a fixed sheave and a movable sheave. Each movable sheave is configured to be able to contact and separate from the fixed sheave by a hydraulic actuator. V-shaped grooves are formed between the opposed surfaces of the fixed sheave and the movable sheave of the primary pulley and the secondary pulley, respectively. A belt is wound around the V groove of the primary pulley and the V groove of the secondary pulley.

  Then, while increasing the groove width (pulley width) of the V-groove of one pulley and narrowing the pulley width of the V-groove of the other pulley, the belt winding radius (effective diameter) for each pulley is continuously increased. To change the gear ratio steplessly. Further, the torque transmitted in the belt type continuously variable transmission is a torque corresponding to a load acting in a direction in which the belt and the pulley are brought into contact with each other. For this reason, the belt is sandwiched by pulleys so as to apply tension to the belt.

  As described above, in the belt type continuously variable transmission, the belt is clamped by the pulley in order to apply tension to the belt, and the belt clamping state by the pulley is changed in order to change the gear ratio (shift). . For this reason, conventionally, as described in Patent Document 1, for example, in a belt-type continuously variable transmission, a hydraulic pressure corresponding to a required torque represented by an engine load or the like is supplied to a hydraulic actuator on the secondary pulley side. The required transmission torque capacity is secured, and the hydraulic pressure for shifting is supplied to the hydraulic actuator on the primary pulley side, and the pulley width of the secondary pulley is changed at the same time the pulley width of the primary pulley is changed. .

  By the way, in a belt-type continuously variable transmission, when the vehicle stops suddenly, a so-called belt return failure state may occur. In other words, when the belt type continuously variable transmission stops as the vehicle stops, it becomes impossible to perform gear shifting. For this reason, for example, when the time until the stop is short, such as when the vehicle suddenly stops, the speed ratio is not returned to the speed ratio (maximum speed ratio γmax) that is normally set at the time of starting. There may not be. In other words, the belt winding position may return only to a position on the speed ratio side (speed increasing side, upshift side) that is smaller than the position corresponding to the maximum speed ratio γmax.

  When the vehicle starts in such a belt return failure state, the belt type continuously variable transmission performs feedback control so as to rapidly set the speed ratio to the maximum speed ratio γmax. Specifically, this shift control is executed by rapidly expanding the pulley width of the primary pulley to a state corresponding to the maximum gear ratio γmax. At this time, the hydraulic pressure supplied to the hydraulic actuator on the primary pulley side is executed. Decreases rapidly. Accordingly, the hydraulic oil is rapidly discharged from the hydraulic actuator on the primary pulley side. As a result, the belt may loosen and slip may occur between the belt and the pulley.

Conventionally, in order to prevent such belt slipping, for example, as shown in Patent Document 1, when starting in a state where the belt return is poor, a shift gain different from that in the normal feedback control described above is used. I am trying to set it. At this time, as shown in FIG. 6, the set shift gain is a predetermined value that is set in advance, and is smaller than that in the case of normal feedback control. The shift gain is an amount associated with the supply / discharge flow rate of the hydraulic oil to the hydraulic actuator for performing a shift, and for example, calculates the duty ratio of the control signal for the solenoid valve connected to the hydraulic actuator on the primary pulley side. For the coefficient. In this case, the larger the shift gain, the greater the discharge flow rate from the hydraulic actuator on the primary pulley side. Along with this, the changing speed at which the pulley width of the primary pulley expands increases, and the changing speed of the gear ratio toward the deceleration side (downshift side) increases. Conversely, the smaller the shift gain, the smaller the discharge flow rate from the hydraulic actuator on the primary pulley side. Along with this, the changing speed at which the pulley width of the primary pulley increases is reduced, and the changing speed of the gear ratio toward the deceleration side (downshift side) is reduced. Note that the range indicated by Z1 in FIG. 6 (range of γz to γmax) is a range in which belt slip does not occur even when normal shift control is performed at the start of the vehicle, that is, even if the shift gain is not set separately. And is in the vicinity of the target gear ratio (maximum gear ratio γmax) that is normally set when the vehicle starts.
JP 2001-330122 A

  Conventionally, when starting in a belt return failure state, the transmission gain that is set separately has a predetermined value, and thus has the following problems.

  As the shift gain, a small value is set in order to prevent the occurrence of belt slip even in a range where the degree of belt return failure is large (for example, a range indicated by Z3 in FIG. 6). However, in this case, since the discharge flow rate from the hydraulic actuator on the primary pulley side is set small, the pulley width of the primary pulley gradually increases, and the gear ratio gradually changes toward the downshift side. As a result, there is a problem that the speed change cannot be performed quickly in a range where the degree of belt return failure is small (for example, a range indicated by Z2 in FIG. 6), and the speed change tracking performance is deteriorated.

  Note that if a large value is set as the shift gain, the discharge flow rate from the hydraulic actuator on the primary pulley side is set large, so that it is possible to ensure shift-following performance in a range where the degree of belt return failure is small, but the primary pulley As a result of the rapid expansion of the pulley width, belt slippage cannot be prevented in a range where the degree of belt return failure is large.

  Therefore, in the past, it has been difficult to achieve both the prevention of belt slip in a range where the degree of belt return failure is large and the improvement of shift tracking performance in a range where the degree of belt return failure is small. .

  The present invention has been made in view of such problems, and prevents the occurrence of belt slip in a range where the degree of belt return failure is large, and improves shift tracking performance in a range where the degree of belt return failure is small. It is an object of the present invention to provide a shift control device for a belt-type continuously variable transmission that can be compatible with the above.

  In the present invention, means for solving the above-described problems are configured as follows. That is, according to the present invention, a belt is stretched between a driving pulley provided on the driving shaft and a driven pulley provided on the driven shaft so as to be able to transmit power, and the pulley width of both pulleys is changed. When configured so as to change the gear ratio, and the actual gear ratio at the start of the vehicle deviates beyond the predetermined range to the speed increase side with respect to the target gear ratio normally set at the start of the vehicle, In a shift control device for a belt-type continuously variable transmission configured to change the gear ratio to the deceleration side when the vehicle starts, when the gear ratio is changed to the deceleration side when the vehicle starts, the degree of deviation at the start In the range where the pulley width is large, the pulley width change speed is set to be small, and in the range where the departure deviation is small, speed setting means is provided to set the pulley width change speed to be large. It is.

  According to the above configuration, in the range where the deviation degree at the start is large, that is, in the range where the degree of belt return failure is large, the speed of change of the pulley width is set to be small. Can be prevented. On the other hand, in the range where the degree of deviation at the start is small, that is, in the range where the degree of belt return failure is small, the pulley width change speed is set to be large. Becomes larger. As a result, the shift can be performed quickly, and the shift tracking performance can be improved.

  Further, according to the present invention, a belt is stretched between a driving side pulley provided on the driving side shaft and a driven side pulley provided on the driven side shaft so that power can be transmitted, and a pulley width of the driving side pulley is increased by a hydraulic actuator. It is configured to change the speed ratio by changing the actual speed ratio at the start of the vehicle and deviates beyond the predetermined range to the speed increase side with respect to the target speed ratio normally set at the start of the vehicle. In the shift control device for a belt-type continuously variable transmission configured to change the gear ratio to the deceleration side when the vehicle starts, the start is performed when the gear ratio is changed to the deceleration side when the vehicle starts. In a range where the degree of deviation in time is large, the hydraulic oil discharge flow rate to the hydraulic actuator is set small, while in a range where the degree of deviation in starting is small, the hydraulic actuator It is characterized in that it comprises a flow rate setting means to set a large discharge flow rate of the hydraulic oil.

  According to the above configuration, the hydraulic oil discharge flow rate to the hydraulic actuator is set small in a range where the deviation degree at the start is large, that is, in a range where the degree of belt return failure is large, so that the pulley width changes gently. become. As a result, it is possible to prevent the belt from loosening and the belt slippage resulting therefrom. On the other hand, in a range where the degree of deviation at the time of starting is small, that is, a range where the degree of belt return failure is small, the hydraulic oil discharge flow rate to the hydraulic actuator is set to be large. The rate of change increases. As a result, the shift can be performed quickly, and the shift tracking performance can be improved.

  In the present invention, the flow rate setting means sets a shift gain for calculating a duty ratio of a signal to a solenoid valve connected to the hydraulic actuator to be small in a range where the deviation degree at the start is large, The discharge flow rate of the hydraulic oil to the hydraulic actuator is controlled by setting it large within a range where the deviation degree at the start is small.

  Further, in the present invention, the flow rate setting means is configured so that the actual speed ratio after the start of the vehicle deviates beyond the predetermined range to the speed increasing side with respect to the target speed ratio, even after the start of the vehicle. Preferably, the shift gain is set based on a relationship in which the shift gain increases as the degree of deviation after the start decreases.

  Here, if the shift gain set at the start of the vehicle does not change, if the degree of divergence at the start is large (when the degree of belt return failure is large), if the shift gain is set small, the discharge to the hydraulic actuator The flow rate is kept small. In this case, it takes a considerable amount of time to change the gear ratio to the deceleration side until the degree of deviation after the start does not exceed the predetermined range.

  On the other hand, according to the above configuration, the discharge flow rate from the hydraulic actuator is set to be larger as the gear ratio is changed to the deceleration side. Therefore, the speed of change of the speed ratio increases as the speed ratio changes to the deceleration side. As a result, it is possible to reduce the time required to change the speed ratio to the deceleration side to the extent that the deviation after starting does not exceed the predetermined range. As a result, even when the degree of belt return failure when the vehicle is stopped is large, it is possible to improve the shift following ability. Further, even when the degree of belt return failure when the vehicle is stopped is small, the shift tracking performance can be improved more effectively.

  According to the present invention, in the range where the degree of belt return failure is large, the speed of change of the pulley width is small, so that loosening of the belt and slippage of the belt resulting therefrom can be prevented. On the other hand, in the range where the degree of belt return failure is small, the speed of change of the pulley width increases, and accordingly, the speed of change of the gear ratio toward the deceleration side increases. As a result, the shift can be performed quickly, and the shift tracking performance can be improved.

  The best mode for carrying out the present invention will be described with reference to the accompanying drawings. Below, the example which applied this invention to the belt-type continuously variable transmission mounted in vehicles, such as a motor vehicle, is demonstrated. A belt type continuously variable transmission mounted on a front engine / front drive (FF) type vehicle will be described as an example.

  First, the overall configuration of a transaxle equipped with a belt type continuously variable transmission will be described.

  FIG. 1 is a skeleton diagram of a transaxle when a belt type continuously variable transmission is applied to an FF vehicle. In the example shown in FIG. 1, the engine 1 is used as a drive source of the vehicle. The type of the engine 1 is not particularly limited. In the following, as the engine 1, so-called direct injection capable of homogeneous combustion and stratified combustion is performed by directly injecting fuel into the cylinder and controlling the injection amount and timing. An example will be described in which a gasoline engine or a gasoline engine equipped with an electronic throttle valve that can electrically freely control the throttle opening is employed. That is, the engine 1 is configured to be electrically controllable, and an electronic control unit (E / G • ECU) 400 for executing the control is provided. The E / G • ECU 400 is configured by a microcomputer mainly including an arithmetic processing unit (CPU or MPU), a storage device (RAM and ROM), and an input / output interface.

  A transaxle 3 is provided on the output side of the engine 1. The transaxle 3 includes a transaxle housing 4 attached to the output side (side of the vehicle) of the engine 1, and the engine in the transaxle housing 4. 1 has a transaxle case 5 attached to the opening end opposite to 1 and a transaxle rear cover 6 attached to the opening end opposite to the transaxle housing 4 in the transaxle case 5 in this order. . A torque converter (T / C) 7 is provided inside the transaxle housing 4, and a forward / reverse switching mechanism 8, a belt type continuously variable transmission (inside the transaxle case 5 and the transaxle rear cover 6). CVT) 9, a final reduction gear 10 having a differential mechanism, and the like are provided.

  An input shaft 11 is provided on the same axis as the crankshaft 2 inside the transaxle housing 4, and a turbine runner 13 is attached to an end of the input shaft 11 on the engine 1 side. On the other hand, a front cover 15 is connected to the end of the crankshaft 2 via a drive plate 14, and a pump impeller 16 is connected to the front cover 15. The turbine runner 13 and the pump impeller 16 are arranged to face each other, and a stator 17 is provided inside the turbine runner 13 and the pump impeller 16. An oil pump 20 is provided between the torque converter 7 and the forward / reverse switching mechanism 8.

  As the operation of the torque converter 7, the pump impeller 16 rotates through the drive plate 14 and the front cover 15 as the crankshaft 2 is rotated by driving the engine 1, and the hydraulic fluid (hydraulic oil supplied from the oil pump 20 is driven. ) Starts to rotate as the turbine runner 13 is dragged. When the rotational speed difference between the pump impeller 16 and the turbine runner 13 is large, the stator 17 converts the flow of hydraulic fluid into a direction that assists the rotation of the pump impeller 16.

  When the vehicle speed reaches a predetermined speed after the vehicle starts, the lockup clutch 18 is operated so that the power transmitted from the engine 1 to the front cover 15 is mechanically and directly transmitted to the input shaft 11. Become. Further, the fluctuation of the torque transmitted from the front cover 15 to the input shaft 11 is absorbed by the damper mechanism 19.

  The forward / reverse switching mechanism 8 is provided in a power transmission path between the input shaft 11 and the belt type continuously variable transmission 9. The forward / reverse switching mechanism 8 has a double pinion type planetary gear mechanism 24. The planetary gear mechanism 24 includes a sun gear 25 provided on the input shaft 11, a ring gear 26 disposed concentrically with the sun gear 25 on the outer peripheral side of the sun gear 25, and an inner pinion gear 27 meshed with the sun gear 25. The inner pinion gear 27 and the outer pinion gear 28 meshed with the ring gear 26, the pinion gears 27 and 28 are supported so as to be able to rotate, and the pinion gears 27 and 28 can revolve integrally around the sun gear 25. And a carrier 29 held in a state.

  The carrier 29 is connected to a primary shaft (transmission input shaft) 30 described later of the belt type continuously variable transmission 9. A forward clutch CL for connecting / disconnecting the power transmission path between the carrier 29 and the input shaft 11 and a reverse brake BR for controlling rotation / fixation of the ring gear 26 are provided. The power transmission path is changed by controlling the forward clutch CL and the reverse brake BR so that the forward rotation power (forward rotation direction) and the reverse rotation power (reverse rotation direction) can be switched.

  The belt type continuously variable transmission 9 includes a primary shaft (driving side shaft) 30 disposed on the same axis as the input shaft 11 and a secondary shaft (driven shaft) 31 disposed in parallel to the primary shaft 30. Have. The primary shaft 30 is rotatably supported by bearings 32 and 33. The secondary shaft 31 is rotatably supported by bearings 34 and 35.

  A primary pulley (driving side pulley) 36 is provided on the primary shaft 30 side, and a secondary pulley (driven pulley) 37 is provided on the secondary shaft 31 side. In addition, rotation speed sensors 71 and 72 are provided for detecting the rotation speeds of the primary shaft 30 and the secondary shaft 31 every predetermined time.

  The primary pulley 36 has a fixed sheave 38 formed integrally with the primary shaft 30 and a movable sheave 39 configured to be movable in the axial direction of the primary shaft 30. A V-shaped groove 40 is formed between the opposed surfaces of the fixed sheave 38 and the movable sheave 39. In addition, a hydraulic actuator 41 that moves the movable sheave 39 in the axial direction of the primary shaft 30 to move the movable sheave 39 and the fixed sheave 38 closer to or away from each other is provided. In other words, the movable sheave 39 is moved forward and backward with respect to the fixed sheave 38 by applying a predetermined hydraulic pressure to the working hydraulic chamber formed in the hydraulic actuator 41.

  On the other hand, the secondary pulley 37 similarly has a fixed sheave 42 formed integrally with the secondary shaft 31 and a movable sheave 43 configured to be movable in the axial direction of the secondary shaft 31. A V-shaped groove 44 is formed between the surfaces facing the movable sheave 43. In addition, a hydraulic actuator 45 that moves the movable sheave 43 and the fixed sheave 42 closer to and away from each other by moving the movable sheave 43 in the axial direction of the secondary shaft 31 is provided. That is, the movable sheave 43 is moved forward and backward with respect to the fixed sheave 42 by applying a predetermined hydraulic pressure to a working hydraulic chamber formed in the hydraulic actuator 45.

  A belt 46 is wound around the groove 40 of the primary pulley 36 and the groove 44 of the secondary pulley 37. The belt 46 is configured as a so-called push-type metal belt, and has a number of metal pieces and a plurality of rings made of steel or the like.

  And in the belt type continuously variable transmission 9, by increasing the groove width (pulley width) of the groove of one pulley of the primary pulley 36 and the secondary pulley 37 and reducing the pulley width of the groove of the other pulley, The gear ratio is continuously changed by continuously changing the winding radius (effective diameter) of the belt 46 with respect to each pulley.

  Further, a counter drive gear 47 is fixed to the secondary shaft 31, and this counter drive gear 47 is supported by bearings 48 and 49. A parking gear PG is provided between one bearing 35 (the bearing on the transaxle rear cover 6 side) that supports the secondary shaft 31 and the secondary pulley 37.

  The intermediate shaft 50 parallel to the secondary shaft 31 is supported by bearings 51 and 52 in the power transmission path between the counter drive gear 47 and the final reduction gear 10 of the belt type continuously variable transmission 9. It is arranged. The intermediate shaft 50 is provided with a counter driven gear 53 that meshes with the counter drive gear 47 and a final drive gear 54.

  The final reduction gear 10 has a hollow differential case 55 that is rotatably supported by bearings 56 and 57, and a final ring gear 58 that meshes with the final drive gear 54 is provided on the outer periphery of the differential case 55. Inside the differential case 55, a pinion shaft 59 to which two pinion gears 60, 60 are attached is disposed. Two side gears 61 and 61 are meshed with the pinion gear 60 and are connected to wheels 63 via left and right drive shafts 62 and 62, respectively.

  The hydraulic pressure generated by the oil pump 20 is supplied to the hydraulic actuator 41 on the primary pulley 36 side and the hydraulic actuator 45 on the secondary pulley 37 side of the belt-type continuously variable transmission 9 via the hydraulic control circuit 200, respectively. Is done. The hydraulic control circuit 200 draws the hydraulic oil sucked from the oil pan 21 and discharged by the oil pump 20 from the primary pulley 36 (the movable sheave 39 is moved forward and backward) and the secondary pulley 37 is controlled (the movable sheave 43 is moved). The hydraulic pressure supplied to the primary hydraulic actuator 41 and the hydraulic pressure supplied to the secondary hydraulic actuator 45 are independently controlled so that the hydraulic pressure is suitable for the forward / backward movement operation.

  Specifically, the hydraulic actuator 45 on the secondary pulley 37 side is supplied with a hydraulic pressure corresponding to a required torque obtained based on an output request typified by the accelerator opening, and presses the movable sheave 43 toward the fixed sheave 42 side. By sandwiching the belt 46, tension necessary to transmit torque is applied to the belt 46.

  Further, hydraulic pressure is supplied to the hydraulic actuator 41 on the primary pulley 36 side so as to have a gear ratio that matches the actual rotational speed of the primary shaft 30 with the target rotational speed. That is, by changing the pulley width of the primary pulley 36 and the pulley width of the secondary pulley 37, the wrapping radius of the belt 46 around the pulleys 36 and 37 is changed to be large and small so that the speed change is executed. More specifically, the shift is executed by feedback-controlling the hydraulic pressure supplied to the hydraulic actuator 41 on the primary pulley 36 side based on the rotational speed deviation between the actual rotational speed of the primary shaft 30 and the target rotational speed. It has become. The gear ratio is changed steplessly between the maximum gear ratio γmax and the minimum gear ratio γmin.

  Here, when increasing the gear ratio, that is, when downshifting, the hydraulic oil is discharged from the hydraulic actuator 41 on the primary pulley 36 side to increase the pulley width of the primary pulley 36. The hydraulic actuator 41 is connected to a flow control valve (flow control valve for executing a downshift) connected to the drain, and a control signal input from a CVT / ECU 300 described later is connected to the flow control valve. A solenoid valve whose output pressure increases according to the duty ratio is connected. In this case, the hydraulic oil discharge flow rate to the hydraulic actuator 41 is controlled by controlling the duty ratio of the control signal for the solenoid valve. At this time, by increasing the discharge flow rate of the hydraulic oil, the transmission speed of the transmission ratio increases.

  Further, in the case of reducing the gear ratio, that is, in the case of an upshift, the hydraulic oil is supplied to the hydraulic actuator 41 on the primary pulley 36 side to reduce the pulley width of the primary pulley 36. The hydraulic actuator 41 is connected to a flow rate control valve (flow rate control valve for performing upshift) to which line pressure is supplied, and the solenoid valve is connected to the flow rate control valve. In this case, the supply flow rate of hydraulic oil to the hydraulic actuator 41 is controlled by controlling the duty ratio of the control signal for the solenoid valve. At this time, by increasing the supply flow rate of the hydraulic oil, the transmission speed of the transmission ratio increases.

  The shift control of the belt type continuously variable transmission 9 is executed by an electronic control unit (CVT / ECU) 300. The CVT / ECU 300 is configured by a microcomputer mainly including an arithmetic processing unit (CPU or MPU), a storage device (RAM and ROM), and an input / output interface.

  In addition to the signals from the rotation speed sensors 71 and 72, various parameters indicating the state of the transaxle 3, such as the torque ratio of the torque converter 7 and the vehicle speed, are input to the CVT / ECU 300. . On the other hand, the E / G • ECU 400 is input with various parameters indicating the operating state of the engine 1, such as engine speed, accelerator opening, throttle opening sensor signal, etc., and information on the calculation result is required. Is input to the CVT / ECU 300 accordingly.

  In this way, information such as the rotational speed Np of the primary shaft 30 and the rotational speed Ns of the secondary shaft 31 by the rotational speed sensors 71 and 72, and the vehicle speed, etc., to the CVT / ECU 300, as well as various sensors and calculation result signals Is input, the shift control of the belt-type continuously variable transmission 9 is performed so as to obtain a required gear ratio and the like based on a map or the like obtained in advance through experiments or the like. In this case, a control signal is sent from the CVT / ECU 300 to the hydraulic control circuit 200 to control the supply / discharge flow rate of hydraulic oil to the hydraulic actuators 41 and 45.

  As a feature of the present embodiment, the belt-type continuously variable transmission 9 has a belt return failure state. When the vehicle starts with the belt return failure state, the shift control of the belt-type continuously variable transmission 9 is performed. In the apparatus, a shift gain different from that in the case of normal feedback control is set.

  Specifically, when the vehicle starts, the gear ratio is normally set to the gear ratio in the most decelerated state (maximum gear ratio γmax). However, in the state where the belt return is poor, the gear ratio is the maximum gear ratio that is the target gear ratio. It is smaller than the ratio γmax. That is, the speed ratio is on the speed increasing side (upshift side) compared to the maximum speed ratio γmax, which is the target speed ratio. For this reason, when starting the vehicle in a state where the belt return is poor, gear shift control is performed so as to increase the gear ratio. That is, at the time of start, gear shift control is performed such that the gear ratio is close to the maximum gear ratio γmax that is the target gear ratio. At this time, the shift gain is set with reference to a map as shown in FIG.

  The shift gain is an amount corresponding to the supply / discharge flow rate of the hydraulic oil to the hydraulic actuator for performing a shift. In this embodiment, the shift gain is a coefficient for calculating the duty ratio of the control signal input to the solenoid valve of the hydraulic control circuit 200. In the case of downshifting, the larger the speed change gain, the larger the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side, and the pulley width of the primary pulley 36 quickly increases. Along with this, the speed of change of the gear ratio toward the deceleration side (downshift side) increases. On the contrary, the smaller the shift gain, the smaller the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side, and the pulley width of the primary pulley 36 gradually increases. Accordingly, the speed of change of the gear ratio toward the downshift side is reduced.

  The horizontal axis of FIG. 3 represents the actual speed ratio at the time of stop (actual speed ratio at the time of start). As shown in FIG. 3, the speed change gain to be set has a linear relationship with the actual speed ratio at the start in the range indicated by X2 and X3 (range of γmin to γx). Specifically, the speed change gain is set to be smaller as the actual speed ratio at the start is smaller, and conversely, the speed gain is set to be larger as the actual speed ratio at the time of start is larger. In other words, the shift gain is set so as to decrease as the degree of deviation (gear ratio deviation) between the actual speed ratio at the start and the target speed ratio at the start increases. Is set to be The degree of divergence represents the degree of belt return failure. The greater the degree of divergence, the greater the degree of belt return failure. Conversely, the smaller the degree of divergence, the smaller the degree of belt return failure.

  In the range where the deviation at the time of starting is large as indicated by X3 in FIG. 3, if the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side is increased, the belt 46 may be slipped. Is set to a small value. On the other hand, in the range where the departure degree is small as indicated by X2 in FIG. 3, even if the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side is increased, the belt 46 can slip. Therefore, the shift gain is set to be large.

  Next, with reference to the flowchart of FIG. 2, the shift control of the belt-type continuously variable transmission that is performed when the vehicle starts with a bad belt return state will be described.

  First, in step ST1, it is determined whether or not a belt return failure state has occurred in the belt-type continuously variable transmission 9 when the vehicle is stopped. Here, whether or not the actual speed ratio at the start of the vehicle deviates beyond a predetermined range set in advance to the upshift side with respect to the target speed ratio (maximum speed ratio γmax) that is normally set at the time of start of the vehicle. Is determined. In other words, it is determined whether or not the actual gear ratio at the start of the vehicle is less than a predetermined value set in advance. The predetermined range means a range in which belt slip does not occur even when normal shift control is performed at the start of the vehicle, and a range in the vicinity of a target speed ratio (maximum speed ratio γmax) that is normally set at the start of the vehicle. It is. For example, the predetermined range is set to a range indicated by X1 in FIG. 3 (range of γx to γmax), and the predetermined value is set to γx in FIG.

  In the belt type continuously variable transmission 9, the gear ratio (Np / Ns) is calculated based on the rotation speed Np of the primary shaft 30 and the rotation speed Ns of the secondary shaft 31 detected by the rotation speed sensors 71 and 72. . In this embodiment, based on the rotation speed Np of the primary shaft 30 and the rotation speed Ns of the secondary shaft 31 detected by the rotation speed sensors 71 and 72 at the time of stop, the actual speed ratio at the time of stop (actual speed ratio at the time of start) Further, the degree of deviation at the time of starting described above is obtained to determine whether or not a belt return failure state occurs when the vehicle is stopped, and the degree of the belt return failure is detected.

  If the deviation at the start does not exceed the predetermined range (when the actual gear ratio at the start of the vehicle is greater than or equal to a predetermined value), it is determined that no belt return failure has occurred. Then, this shift control is terminated. On the other hand, when the deviation degree at the time of starting exceeds a predetermined range (when the actual gear ratio at the time of starting of the vehicle is less than a predetermined value), the belt return failure state has occurred. The determination is made and the process proceeds to step ST2.

  If the start of the vehicle is detected in step ST2, next, a shift gain is set in step ST3. In step ST3, a map (FIG. 3) is referred to, and a shift gain corresponding to the degree of deviation at the start is acquired. In other words, the gear gain corresponding to the actual gear ratio at the time of stop (actual gear ratio at the time of start) is acquired. In this manner, the duty ratio of the control signal input to the solenoid valve of the hydraulic control circuit 200 is calculated based on the set shift gain, and the hydraulic oil discharge flow rate to the hydraulic actuator 41 is calculated based on the duty ratio. Be controlled. As a result, the gear ratio changes to the downshift side, and the degree of deviation from the target gear ratio gradually decreases.

  Specifically, the shift gain is set to be smaller as the deviation degree at the time of starting is larger (as the actual gear ratio at the time of starting is smaller). For this reason, the larger the degree of deviation at the time of starting, the smaller the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side, and the smaller the moving speed of the movable sheave 39 of the primary pulley 36 is set. That is, the speed at which the pulley width of the primary pulley 36 increases is set small. As a result, the speed of change of the gear ratio toward the downshift side is set to be small. Therefore, in a range where the degree of deviation at the time of starting is large (for example, a range indicated by X3 in FIG. 3), the gear ratio gradually changes to the downshift side.

  On the other hand, the shift gain is set to be larger as the deviation degree at the time of starting is smaller (as the actual gear ratio at the time of starting is larger). For this reason, as the degree of deviation at the time of starting is smaller, the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side is set higher, and the moving speed of the movable sheave 39 of the primary pulley 36 is set higher. That is, the speed at which the pulley width of the primary pulley 36 is increased is set large. As a result, the speed of change of the gear ratio toward the downshift side is set to be large. Therefore, in a range where the degree of deviation at the time of starting is small (for example, a range indicated by X2 in FIG. 3), the gear ratio is rapidly changed to the downshift side.

  In step ST4, it is determined whether or not the belt return failure state has been resolved after the vehicle has started. Here, the degree of divergence (the degree of divergence after start) between the gear ratio changed to the downshift side by the flow control (speed control) in step ST3 and the target gear ratio is within the predetermined range (gamma x to γmax in FIG. 3). It is determined whether or not the range is exceeded. In other words, it is determined whether or not the gear ratio changed to the downshift side (actual gear ratio after starting) after the start of the vehicle is greater than or equal to the predetermined value (γx in FIG. 3).

  If the deviation after starting does not exceed the predetermined range (when the actual gear ratio after starting is greater than or equal to the predetermined value), it is determined that the belt return failure state has been resolved. The shift control is terminated. On the other hand, when the deviation after starting exceeds the predetermined range (when the actual gear ratio after starting is less than the predetermined value), the deviation after starting exceeds the predetermined range. Until this happens, the flow rate control based on the shift gain set in step ST3 is continued.

  According to the shift control device for a belt-type continuously variable transmission according to the present embodiment, the shift gain is set according to the degree of belt return failure, not a predetermined value, unlike the conventional example. Therefore, the following effects can be obtained.

  As described above, the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side is set small in a range where the degree of deviation at the time of starting is large (a range where the degree of belt return failure is large). Along with this, the pulley width of the primary pulley 36 is gradually increased, so that it is possible to prevent the belt 46 from being loosened and slipping of the belt 46 resulting therefrom.

  On the other hand, in the range where the degree of deviation at the time of starting is small (the range where the degree of belt return failure is small), the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side is set to be large, and the gear ratio is downshifted accordingly. The rate of change to the side increases. As a result, the shift can be performed quickly, and the shift tracking performance can be improved.

  As described above, it is possible to achieve both the prevention of the occurrence of belt slip in the range where the degree of belt return failure is large and the improvement of the shift tracking performance in the range where the degree of belt return failure is small.

  The embodiment of the present invention has been described above. However, the embodiment shown here is an example and can be variously modified.

  The configuration of the hydraulic control circuit for performing the shift control described above is an example, and other configurations may be adopted.

  In the above-described embodiment, the case where the actual speed ratio and the degree of deviation when the vehicle is stopped is used as it is as the actual speed ratio and the degree of deviation when the vehicle is started, but when the vehicle is started, the rotational speed sensors 71 and 72 are used. Based on the detected rotation speed Np of the primary shaft 30 and the rotation speed Ns of the secondary shaft 31, the actual gear ratio at the start and the deviation degree at the start are obtained, and the actual transmission ratio at the start and the deviation degree at the start. It is also possible to set the shift gain based on the above.

  The map of FIG. 3 referred to when setting the shift gain is an example, and the relationship between the set shift gain and the actual gear ratio at the start may be a relationship other than linear. Instead of the map, it is also possible to set the shift gain by referring to the table. In short, it is sufficient that the shift gain can be set small in a range where the degree of belt return failure is large and large in a range where the degree of belt return failure is small.

  In the above embodiment, the case where the shift gain is set at the start of the vehicle has been described. However, the shift gain may be set not only at the start of the vehicle but also after the start. That is, after the vehicle starts, the transmission gain is set as needed. In this case, it is preferable to set the transmission gain by following the transmission ratio that changes to the downshift side after the vehicle starts. For example, as shown in FIGS. 4 and 5, the shift gain can be set according to the current actual gear ratio after the vehicle starts.

  In the flowchart of FIG. 4, Step ST11 and Step ST12 are the same as Step ST1 and Step ST2 of the above embodiment, but Step ST13 and Step ST14 are different from Step ST3 and Step ST4 of the above embodiment. Here, different points will be briefly described.

  In step ST13, the map (FIG. 5) is referred to, and the point corresponding to the current actual speed ratio (including the actual speed ratio at the time of start) is acquired as the speed change gain. Here, the horizontal axis of FIG. 5 represents the current actual gear ratio. The current actual gear ratio can be obtained based on the rotation speed Np of the primary shaft 30 and the rotation speed Ns of the secondary shaft 31 by the rotation speed sensors 71 and 72 detected every predetermined time. As shown in FIG. 5, the speed change gain to be set has a linear relationship with the current actual speed ratio in the range indicated by Y2 and Y3 (range of γmin to γy). Note that the map in FIG. 5 is an example, and the relationship between the set shift gain and the current actual gear ratio may be a relationship other than linear, but as the current actual gear ratio becomes larger (the divergence after the start) It is preferable that the shift gain to be set increases as the degree decreases. That is, it is preferable that the transmission gain be in a relationship that increases following the transmission ratio that changes to the downshift side after the vehicle starts.

  In step ST14, when the gear ratio (current actual gear ratio) after changing to the downshift side by the flow rate control (speed control) in step ST13 is less than a predetermined value (for example, γy in FIG. 5). Is different from the above embodiment in that the process proceeds to step ST13. Therefore, steps ST13 and ST14 are repeatedly executed until the current actual gear ratio becomes equal to or greater than a predetermined value.

  According to this shift control, the following effects are also obtained.

  Here, if the shift gain set at the start of the vehicle does not change, if the deviation at the start is large (the degree of belt return failure is large), if the shift gain is set small, the primary pulley 36 side The discharge flow rate from the hydraulic actuator 41 is maintained in a state where it is set small. In this case, it takes a considerable amount of time to change the gear ratio until it exceeds the predetermined value.

  On the other hand, as described above, if the transmission gain is set based on the relationship that the transmission gain increases as the current actual transmission ratio increases even after the vehicle starts, the transmission ratio can be increased. The greater the change to the downshift side, the greater the discharge flow rate from the hydraulic actuator 41 on the primary pulley 36 side. Therefore, the speed of change of the speed ratio increases as the speed ratio changes to the downshift side. As a result, it is possible to shorten the time required to change the gear ratio until it exceeds the predetermined value. As a result, even when the degree of belt return failure when the vehicle is stopped is large, it is possible to improve the shift following ability. Further, even when the degree of belt return failure when the vehicle is stopped is small, the shift tracking performance can be improved more effectively.

  The vehicle on which the belt type continuously variable transmission is mounted is not limited to the FF method, and may be a vehicle of a front engine / rear drive (FR) method or another drive method, for example.

  The gasoline engine cited as the drive source of the vehicle is an example, and the present invention can be applied to a vehicle using a diesel engine as a drive source and a hybrid vehicle.

It is a skeleton figure which shows the transaxle provided with the belt-type continuously variable transmission. It is a flowchart which shows an example of the shift control of the belt-type continuously variable transmission performed when starting in the state of a belt return defect. It is a figure which shows an example of the transmission gain set in the transmission control apparatus of a belt-type continuously variable transmission, when starting in the state of a belt return defect. 7 is a flowchart showing another example of the shift control of the belt type continuously variable transmission performed when starting in a state where the belt return is poor. It is a figure which shows the other example of the transmission gain set in the transmission control apparatus of a belt-type continuously variable transmission, when starting in the state of a belt return defect. It is a figure which shows the transmission gain set in the transmission control apparatus of the conventional belt-type continuously variable transmission, when starting in the state of a belt return defect.

Explanation of symbols

9 Belt type continuously variable transmission 30 Primary shaft 31 Secondary shaft 36 Primary pulley 37 Secondary pulley 40, 44 Groove 41, 45 Hydraulic actuator 46 Belt 71, 72 Speed sensor 200 Hydraulic control circuit 300 CVT / ECU

Claims (4)

A belt is stretched between a driving pulley provided on the driving shaft and a driven pulley provided on the driven shaft so that power can be transmitted, and the gear ratio is changed by changing the pulley width of both pulleys. And
If the actual gear ratio at the start of the vehicle deviates beyond the predetermined range to the speed increase side with respect to the target gear ratio that is normally set at the start of the vehicle, the gear ratio is changed to the deceleration side when the vehicle starts In a shift control device for a belt-type continuously variable transmission configured to:
When changing the gear ratio to the deceleration side at the start of the vehicle, the pulley width change speed is set small in a range where the deviation degree at the start is large, while the pulley is set in a range where the deviation degree at the start is small. A speed change control device for a belt-type continuously variable transmission, comprising speed setting means for setting a change speed of a width large. A belt is stretched between a driving pulley provided on the driving side shaft and a driven pulley provided on the driven side shaft so as to be able to transmit power, and a pulley ratio of the driving side pulley is changed by a hydraulic actuator to change the transmission ratio. And is configured to change
If the actual gear ratio at the start of the vehicle deviates beyond the predetermined range to the speed increase side with respect to the target gear ratio that is normally set at the start of the vehicle, the gear ratio is changed to the deceleration side when the vehicle starts In a shift control device for a belt-type continuously variable transmission configured to:
When changing the gear ratio to the deceleration side when the vehicle starts, the hydraulic oil discharge flow rate with respect to the hydraulic actuator is set small in a range where the deviation degree at the start is large, while in the range where the deviation degree at the start is small. A shift control device for a belt-type continuously variable transmission, comprising flow rate setting means for setting a large discharge flow rate of hydraulic oil to the hydraulic actuator.   The flow rate setting means sets a shift gain for calculating a duty ratio of a signal to a solenoid valve connected to the hydraulic actuator to be small in a range where the deviation degree at the start is large, while the deviation at the start time 3. The shift control device for a belt-type continuously variable transmission according to claim 2, wherein the discharge flow rate of the hydraulic oil to the hydraulic actuator is controlled by setting a large value in a small range.   When the actual speed ratio after starting the vehicle deviates beyond the predetermined range to the speed increase side with respect to the target speed ratio, the flow rate setting means determines the divergence after the starting even after the vehicle starts. 4. The shift control device for a belt-type continuously variable transmission according to claim 3, wherein the shift gain is set based on a relationship in which the shift gain increases as the degree decreases.

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