JP2005042884A - Control device of infinitely variable speed transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the sliding start timing and limit clamping force balanced with the input torque in an infinitely variable speed transmission with good accuracy. <P>SOLUTION: This control device of the infinitely variable speed transmission detects slippage between an input/output member and a transmission member in the infinitely variable speed transmission in which the change gear ratio is continuously varied by changing the torque transmission part among the input member, the output member and the transmission member interposed between the input and output members. The control device includes: a slippage determination means for determining slippage; and a slippage starting timing determination means for determining the start timing of slippage from that a deviation between the actual change gear ratio change rate actually measured at a point of time before the slippage and an estimated gear change ratio or the actual gear change ratio change rate is equal to or larger than a predetermined value on the positive side or on the negative side when the slippage is determined by the slippage determination means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device that controls the pinching pressure of a continuously variable transmission, and more particularly to a control device that detects or determines a limit pinching pressure that is commensurate with a slip start time and input torque.

  The belt-type continuously variable transmission and the traction-type continuously variable transmission transmit torque using the frictional force between the belt and the pulley and the shearing force of the traction oil between the disk and the roller. Therefore, the torque capacity of these continuously variable transmissions is set according to the pressure acting on the location where the torque is transmitted.

  The above-mentioned pressure in a continuously variable transmission is referred to as pinching pressure. Increasing the pinching pressure can increase the torque capacity and avoid slipping, but on the other hand, more power than necessary to generate high pressure. There are inconveniences such as consumption or reduction in power transmission efficiency. Therefore, in general, the clamping pressure is set as low as possible within a range in which unintended slip does not occur.

  For example, in a vehicle equipped with a continuously variable transmission, the engine speed can be controlled by the continuously variable transmission to improve fuel efficiency. In order to improve the transmission efficiency as much as possible, the clamping pressure is controlled to be set as low as possible within a range where no slip occurs. For this purpose, it is necessary to detect the pressure at which slip starts (that is, the slip limit pressure or the limit clamping pressure). Conventionally, slip is detected by various methods, and the slip limit pressure is detected.

  For example, Patent Document 1 discloses a transmission having a conical disk pair and a winding transmission node, and the conical disk pair slips by changing a pressing force for sandwiching the winding transmission node. A transmission is described that is configured to determine a limit and adjust the crimping force so as not to exceed the slip limit.

Further, Patent Document 2 describes a control device configured to detect the occurrence of slipping when the absolute value of the actual gear ratio change rate exceeds the absolute value of the theoretical gear ratio change rate.
JP 2001-12593 A JP-A-6-11022

  The friction efficiency described in Patent Document 1 is, for example, oil temperature, and therefore, a time delay from the occurrence of slipping to its detection becomes large, which affects the accuracy of the slip limit of the crimping force. In order to avoid such inconvenience, it is conceivable to detect the occurrence of slip using an actual gear ratio change rate as described in Patent Document 2, for example.

  However, since the slip in the continuously variable transmission is a so-called stick slip in which the slip rotation speed pulsates, the actual gear ratio change rate also changes in magnitude. Therefore, if the occurrence of slip is determined by comparing a relatively small threshold value with the actual gear ratio change rate, there is a high possibility that a temporary rotational fluctuation that does not reach a so-called macro slip is erroneously determined as slip. Become. On the other hand, if the threshold value is increased, the possibility of erroneous determination of slippage is reduced, but after the actual slippage occurs, the slippage determination is established when the slippage becomes large enough to exist. As a result, there is a delay in slip detection. Therefore, if the pressure at the time of slip determination is set to the slip limit, the detection accuracy of the slip limit may be lowered.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a control device that can accurately detect the occurrence of slippage and the limit clamping pressure in a continuously variable transmission. Is.

  In order to achieve the above object, the invention according to claim 1 is characterized in that the transmission ratio is changed by changing the torque transmission portion between the input member and the output member and the transmission member interposed between these input / output members. In a control device for a continuously variable transmission that detects slip between the input / output member and a transmission member in a continuously variable continuously variable transmission, the slip determination means that determines the slip, and the slip determination means When a slip is determined, the deviation between the actual change ratio of the actual speed ratio and the estimated change ratio of the estimated speed ratio before the slip or the actual change ratio of the estimated speed ratio is a predetermined value on the positive or negative side. And a slip start time determining means for determining the slip start time based on being equal to or greater than a value.

  Further, the invention of claim 2 is a continuously variable transmission that continuously changes the speed ratio by changing a torque transmission portion between the input member and the output member and the transmission member interposed between the input / output members. In a control device for a continuously variable transmission that detects slip between the input / output member and a transmission member in a transmission, processing at least one detection signal of a rotational speed and a gear ratio of the input member or output member A slip determining means for determining the slip based on a comparison between the processing value obtained in this way and the first threshold value, and a predetermined prior to the slip when the slip determination by the slip determining means is established. A slip start time determination means for determining, as the start time of the slip, a time point when the processing value first exceeds a second threshold value smaller than the first threshold value within a time width of Characteristic system It is a device.

  Further, the invention of claim 3 is the invention of claim 1 or 2, wherein the clamping pressure gradual reduction means for gradually reducing the clamping pressure for setting the torque capacity between the input / output member and the transmission member to cause the slip. And a limit clamping pressure detecting means for detecting a limit clamping pressure for setting the torque capacity in proportion to the input torque based on the clamping pressure at the slip start timing determined by the slip start timing determining means. It is the control apparatus characterized by having.

  Therefore, according to the first aspect of the present invention, first, slip is determined. This can be determined based on the degree of change in the gear ratio, the magnitude of the gear ratio change rate, the rotational speed of the input member, the rotational speed of the output member, or the rate of change thereof. When the judgment of slip is established, the deviation between the actual gear ratio change rate and the estimated gear ratio change rate or the gear ratio change rate at a time earlier than that is greater than a predetermined value on the positive side or a predetermined value on the negative side. The time point is determined as the slip start time. That is, the behavior leading to the slip is detected retroactively from the slip determination time based on the speed ratio change rate and the start of the slip is determined, so that the slip start timing can be accurately determined.

  According to the second aspect of the present invention, a processed value obtained by processing a detection signal of the rotational speed or the gear ratio of the input / output member is obtained. This processing value is, for example, a differential value of the gear ratio (that is, a gear ratio change rate) or a bandpass filter processing value of the rotation speed of the input member or the output member. The processed value is compared with the first threshold value to determine slippage. For example, when the processing value exceeds the first threshold value, the determination of slip is established. In this case, the processing value in the predetermined time width before the slip determination time is compared with the second threshold value smaller than the first threshold value, and the flow of time from the past toward the slip determination time is compared. Thus, the slip start time is determined based on the time when the processing value exceeds the second threshold value for the first time. As a result, since the start time of the behavior leading to the slip is determined retroactively from the slip determination time, the slip start time can be accurately determined.

  Furthermore, in the invention of claim 3, the slip is caused by gradually decreasing the clamping pressure, and the critical clamping pressure is set based on the clamping pressure at the slip start timing determined from the judgment of the slip and the slip determination timing. Since it is detected, the detection accuracy of the limit clamping pressure can be improved in combination with the accurate determination of the slip start time.

  Next, the present invention will be described based on specific examples. First, a drive mechanism including a continuously variable transmission targeted by the present invention will be described. The present invention can be directed to a continuously variable transmission mounted on a vehicle, and the continuously variable transmission includes a belt. A belt-type continuously variable transmission that uses a torque transmission member, or a toroidal type (traction-type) continuously variable transmission that uses a power roller as a torque transmission member and uses the shearing force of oil (traction oil). is there. FIG. 5 schematically shows an example of a vehicle drive mechanism including a belt-type continuously variable transmission 1, and the continuously variable transmission 1 is connected to a power by a forward / reverse switching mechanism 2 and a torque converter 3. Connected to source 4.

  The power source 4 is the same as a power source mounted on a general vehicle, and is an internal combustion engine such as a gasoline engine, a diesel engine or a natural gas engine, an electric motor, or a combination of an internal combustion engine and an electric motor. A mechanism or the like can be employed. In the following description, the power source 4 is referred to as the engine 4.

  The torque converter 3 connected to the output shaft of the engine 4 has the same structure as that of a conventional torque converter used in general vehicles, and a pump impeller 6 is connected to a front cover 5 to which the output shaft of the engine 4 is connected. A turbine runner 7 that is integrated and faces the pump impeller 6 is disposed adjacent to the inner surface of the front cover 5. The pump impeller 6 and the turbine runner 7 are provided with a large number of blades (not shown). The pump impeller 6 rotates to generate a fluid spiral flow. The spiral runner 7 The turbine runner 7 is rotated by applying torque to the turbine runner 7.

  Further, a stator 8 that selectively changes the flow direction of the fluid fed from the turbine runner 7 and flows into the pump impeller 6 between the pump impeller 6 and the turbine runner 7 on the inner peripheral side thereof. Is arranged. The stator 8 is connected to a predetermined fixing portion 10 via a one-way clutch 9.

  The torque converter 3 includes a lockup clutch 11. The lock-up clutch 11 is arranged in parallel with a substantial torque converter including the pump impeller 6, the turbine runner 7, and the stator 8, and is in a state facing the inner surface of the front cover 5. 7 and is pressed against the inner surface of the front cover 5 by hydraulic pressure, so that torque is directly transmitted from the front cover 5 as an input member to the turbine runner 7 as an output member. The torque capacity of the lockup clutch 11 can be controlled by controlling the hydraulic pressure.

  The forward / reverse switching mechanism 2 is a mechanism that is employed when the rotational direction of the engine 4 is limited to one direction, and outputs the input torque as it is or reversely outputs it. It is configured. In the example shown in FIG. 5, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2.

  That is, a ring gear 13 is arranged concentrically with the sun gear 12, and a pinion gear 14 meshed with the sun gear 12 and the pinion gear 14 and another pinion gear 15 meshed with the ring gear 13 are arranged between the sun gear 12 and the ring gear 13. These pinion gears 14 and 15 are held by a carrier 16 so as to rotate and revolve freely. A forward clutch 17 that integrally connects the two rotating elements (specifically, the sun gear 12 and the carrier 16) is provided, and the direction of the torque that is output by selectively fixing the ring gear 13 A reverse brake 18 for reversing is provided.

  The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and includes a drive pulley 19 as an input member and a driven pulley 20 as an output member that are arranged in parallel to each other. The fixed sheave and the movable sheave that is moved back and forth in the axial direction by the hydraulic actuators 21 and 22 are configured. Therefore, the groove width of each pulley 19 and 20 is changed by moving the movable sheave in the axial direction, and accordingly, the winding radius (pulley 19, pulley) of the belt 23 as a transmission member wound around each pulley 19, 20 is changed. 20 effective diameter) changes continuously, and the gear ratio changes steplessly. The drive pulley 19 is connected to a carrier 16 that is an output element in the forward / reverse switching mechanism 2. These pulleys 19 and 20 and the belt 23 constitute a continuously variable transmission.

  The hydraulic actuator 22 in the driven pulley 20 is supplied with a hydraulic pressure (line pressure or its correction pressure) according to the torque input to the continuously variable transmission 1 via a hydraulic pump and a hydraulic control device (not shown). Yes. Therefore, each sheave in the driven pulley 20 pinches the belt 23, whereby tension is applied to the belt 23, and a clamping pressure (contact pressure) between the pulleys 19, 20 and the belt 23 is ensured. . In other words, the torque capacity corresponding to the clamping pressure is set. On the other hand, the hydraulic actuator 21 in the drive pulley 19 is supplied with pressure oil corresponding to the gear ratio to be set, and is set to a groove width (effective diameter) corresponding to the target gear ratio. .

  A driven pulley 20 that is an output member of the continuously variable transmission 1 is connected to a gear pair 24 and a differential 25, and the differential 25 is connected to left and right drive wheels 26.

  Various sensors are provided in order to detect the operation state (running state) of a vehicle on which the continuously variable transmission 1 and the engine 4 are mounted. That is, the engine rotational speed sensor 27 that detects the output shaft rotational speed Ne of the engine 4 (the input shaft rotational speed of the lockup clutch 11) Ne and outputs a signal, and the turbine that detects the rotational speed of the turbine runner 7 and outputs the signal. A rotational speed sensor 28, an input shaft rotational speed sensor 29 that detects the rotational speed Nin of the driving pulley 19 and outputs a signal, an output shaft rotational speed sensor 30 that detects the rotational speed Nout of the driven pulley 20 and outputs a signal, and the like. Is provided.

  Control of engagement / release of the forward clutch 17 and reverse brake 18, control of the clamping force of the belt 23, control of torque capacity including engagement / release of the lockup clutch 11, and gear ratio In order to perform this control, a transmission electronic control unit (CVT-ECU) 31 is provided. The electronic control device 31 is configured mainly by a microcomputer as an example, performs calculations according to a predetermined program based on input data and data stored in advance, and various states such as forward, reverse or neutral, Further, control such as setting of the required clamping pressure and setting of the gear ratio is executed. In addition, an engine electronic control unit (E-ECU) 32 for controlling the engine 4 is provided, and data is communicated between the electronic control units 31 and 32.

  As described above, the clamping pressure in the continuously variable transmission is preferably as low as possible within a range where torque can be transmitted without causing slipping. Therefore, the control device of the present invention for the continuously variable transmission 1 reduces the clamping pressure based on the hydraulic pressure supplied to the actuator 22 on the driven pulley 20 side, detects the resulting slip, and detects the slip. A slip start time before the detection time is estimated, and the pinching pressure at that point is determined as a limit pinching pressure (that is, a pinching pressure commensurate with the input torque). A specific example of the control will be described below.

  1 and 2 are flowcharts showing an example thereof, and FIGS. 3 and 4 are time charts when the control shown in the flowchart is performed. In FIG. 1, it is first determined whether or not a control start condition is satisfied (step S101). The specific example described here is an example in which the clamping pressure of the continuously variable transmission 1 is reduced, the slip at that time is detected, and the limit clamping pressure is detected based on the detection result. The torque acting on the transmission 1 needs to be stable. Step S102 is for determining the stable state of such torque. Therefore, the control start conditions are, for example, that the vehicle is cruising at medium and high vehicle speeds, that the road surface is a good road with a substantially flat surface, The operating state (traveling state) at that time belongs to the operating region (traveling region) where the learning of the limit clamping pressure has not been completed, there is no abnormality in the control device, and the warm-up is completed Etc.

  If all of these conditions are satisfied, an affirmative determination is made in step S101. In that case, it is determined whether or not this flag F1 is set to "1" (step S102). This flag F1 is a so-called limit pin that is set to "1" when it is detected that the slip in the continuously variable transmission 1, that is, the slip between the belt 23 and one of the pulleys 19 and 20 is detected. This is a pressure detection flag and is initially set to “0”. Accordingly, at the beginning of the control, a negative determination is made in step S102. In this case, the process proceeds to step S103, and the input rotation speed Nin (i) and the output rotation speed Nout (i) of the continuously variable transmission 1 are measured by the sensors 29 and 30 described above. Further, the actual hydraulic pressure Pdact (i) of the hydraulic actuator 22 on the driven pulley 20 side at that time is measured. This can be measured by connecting a sensor (not shown) to a predetermined portion of the hydraulic circuit communicating with the hydraulic actuator 22.

  Next, the actual speed ratio γ (i) and the speed ratio change rate (speed ratio differential value) Δγ (i) at that time are calculated from the measured input speed Nin and output speed Nout (step S104). . Further, an instruction to decrease the hydraulic pressure is given (step S105). The hydraulic pressure is a hydraulic pressure for setting the clamping pressure, which is the time t1 in FIGS. Specifically, in this hydraulic pressure decrease control, a value obtained by subtracting a value ΔPdswp corresponding to a predetermined decrease gradient from the previous hydraulic pressure command value Pdtgt (i-1) of the clamping pressure is used as the current clamping pressure hydraulic command value Pdtgt ( i).

  In the process of gradually decreasing the clamping pressure in this way, the gear ratio change rate Δγ (i) exceeds a predetermined threshold value Ta + on the positive side or a predetermined threshold value Ta− on the negative side. It is determined whether it has been exceeded (below) (step S106). This step S106 is a step for determining slippage in the continuously variable transmission 1. Therefore, each of the threshold values Ta + and Ta- is determined by the change in the speed ratio change rate Δγ (i) due to the slip and the slip. It is a value that can be distinguished from an unaffected change. The absolute values of the threshold values Ta + and Ta− may be different from each other. However, when the absolute values are the same, the absolute value of the speed change ratio Δγ (i) is the positive threshold. It may be determined whether or not the value Ta + is exceeded.

  When the hydraulic pressure is not sufficiently reduced, the clamping pressure is relatively high with respect to the input torque, so that the continuously variable transmission 1 does not slip. Therefore, the gear ratio change rate Δγ (i) is almost zero or a small value close to zero. Therefore, a negative determination is made in step S106. In that case, the gear ratio γ (i), the gear ratio change rate Δγ (i), the actual oil pressure Pdact (i), and the oil pressure command value Pdtgt (i) at that time are stored (step S108), and the process returns.

  On the other hand, when the gear ratio change rate Δγ (i) exceeds any one of the threshold values Ta + and Ta−, an affirmative determination is made in step S106, and a slip determination is established. This is the time t4 in FIGS. At the same time, the flag F1 is set to "1" (step S107). Then, control for detecting the slip start time and the limit clamping pressure is executed.

  That is, as shown in FIG. 2, the number of data Nlimt in the limit clamping pressure detection section is obtained as a function of the speed ratio change rate Δγ (i) at the time of slip detection (step S201). If this is shown in a time chart, it is the time interval Tpreslp from the time t4 to the time t2 before that in FIG. As a general tendency, this time interval Tpreslp (data number Nlimt) is set longer as the gear ratio change rate Δγ (i) at the time of slip detection is larger. This is to lengthen the limit clamping pressure detection period.

  Next, the limit clamping pressure detection variable B is set to the past time point in the time interval Tpreslp (step S202). That is, B = i−Nlimt. Then, the gear ratio change rate Δγ (B) at time B is obtained as a variable A (step S203). It is determined whether or not the variable A (that is, the gear ratio change rate Δγ (B)) exceeds the positive and negative second threshold values Tb + and Tb− (step S204). This step S204 is for determining the start time of the slip. Therefore, the absolute values of the second threshold values Tb + and Tb- are smaller than the first threshold values Ta + and Ta- described above. is there.

  Since the time interval Tpreslp is set to be sufficiently long, slipping has not started at the most past point in the time interval Tpreslp, and therefore a negative determination is made in step S204. In that case, the limit clamping pressure detection variable B is incremented (step S205), and it is determined whether or not the resulting value has reached a value i indicating the time point when the slip determination is established (step S206). If a negative determination is made in step S206, the process returns to step S203. That is, a predetermined time Tpreslp is established from the time when the slip determination is established, and the time is sequentially advanced from the retroactive time t2 to the current time. Whether the speed ratio change rate Δγ (B) at each time exceeds the threshold values Tb + and Tb−. Is determined. This determination may be made by determining whether or not the absolute value of the gear ratio change rate Δγ (B) exceeds the positive threshold value Tb +.

  The slip in the continuously variable transmission 1 is a so-called stick slip in which the gear ratio γ and the gear ratio change rate Δγ pulsate. Therefore, the change in the behavior of the continuously variable transmission 1 reaching the slip determined at the time t4 starts before the time t4. Therefore, the speed ratio change rate Δγ is changed from the past to the present. When sequentially compared with the threshold values Tb + and Tb−, the gear ratio change rate Δγ (B) exceeds the threshold values Tb + and Tb− at a predetermined time point. That is, a positive determination is made in step S204. Since that time (time t3 in FIGS. 3 and 4) is the slip start time, the actual holding pressure Pdact (B) at that time is set to the limit holding pressure Pdlim (step S207).

  The limit clamping pressure detection variable B may reach the value i indicating the current time point (slip determination establishment time) without detecting the start of slipping. To be judged. In this case, the predetermined hydraulic pressure Pdact (Nff) determined based on the actual hydraulic pressure Pdact (i) at the slip determination establishment time t4 or the hydraulic pressure at a predetermined time before that is set to the limit clamping pressure. Pdlim is set (step S208).

  When the slip start time and the limit clamping pressure are detected as described above, since the slip determination has already been established, control for converging the slip is executed. That is, after step S207 or step S208 described above, the process proceeds to step S109 shown in FIG. 1, and it is determined whether or not the slip (slip of the belt 23 in the continuously variable transmission 1) has converged. If a negative determination is made in step S109 because the slip is continuing, a control for preventing a macro slip that is a predetermined slip or more is executed (step S110). As an example, this is control for changing (retarding) the ignition timing in the engine 4 in order to reduce the input torque of the continuously variable transmission 1, and control for increasing the clamping pressure.

  An example is shown in FIG. 4, and the ignition timing of the engine 4 is retarded by a predetermined amount ΔCA simultaneously with the establishment of the slip determination, and is continued for a predetermined time Tdelay. The retardation amount ΔCA and the duration Tdelay can be set based on the time interval Tpredet from the slip start time t3 to the slip determination establishment time t4. The retardation amount ΔCA is feedback-controlled based on the deviation between the estimated value of the gear ratio γ and the actual gear ratio. On the other hand, the clamping pressure is stepped up by a predetermined amount Pdup at a time t5 (see FIG. 4) when a predetermined time Tdelay has elapsed from the slip determination establishment time t4.

  After executing the above macro slip prevention control, the routine returns and is executed again at predetermined time intervals. In that case, since the flag F1 has already been set to "1", an affirmative determination is made in step S102 described above. In that case, the process immediately proceeds to step S109, and it is determined whether or not the belt slip has converged. When the slip continues, the macro slip prevention control is continued. On the contrary, if the belt slip decreases with time, a positive determination is made in step S109. An affirmative determination in step S109 is, for example, the time t6 shown in FIG. 4, which is determined when the deviation between the estimated gear ratio and the actual gear ratio is less than or equal to a predetermined value Δγend. This is because the time point t7 when the engine torque is restored coincides with the time point t7 when the slip becomes almost zero.

  Therefore, when a positive determination is made in step S109, the macro slip prevention control is stopped (step S111). As described above, since the clamping pressure has already been increased, control for returning the ignition timing of the engine 4 to the original is executed in this step S111. Thereafter, correction of the clamping pressure map such as writing or rewriting a value obtained by adding the pressure corresponding to the road surface input to the limit clamping pressure is executed (step S112). Further, control for returning to the normal clamping pressure is executed, the flag is reset, and the stored value is cleared (step S113). That is, a series of control of detection of slipping by reducing the clamping pressure and detection of the limit clamping pressure accompanying it are completed.

  If the control start condition is not satisfied or is no longer satisfied, a negative determination is made in step S101 described above. In this case, it is determined whether macro slip prevention control is being executed (step S114). If a positive determination is made in step S114, the macro slip prevention control is stopped (step S115), and if a negative determination is made in step S114, the process immediately proceeds to step S116 and the normal clamping pressure is determined. Control to return to is executed, the flag is reset, and the store value is cleared.

  As described above, in the control device according to the present invention, the slip in the continuously variable transmission 1 is a so-called stick slip, and the detection signal of the gear ratio and the gear ratio change rate vibrates or pulsates, and therefore the slip determination is performed. Is delayed from the start of slipping, but the start of slipping is detected when the speed ratio change rate in the time width before the predetermined time exceeds a threshold value that is smaller than the threshold value for slip determination. Since the determination is made, it is possible to accurately determine the start time of the slip. Therefore, the detection accuracy of the so-called limit clamping pressure that balances the input torque is improved.

  Here, the relationship between the above-described specific example and the present invention will be briefly described. The functional means in step S106 corresponds to the slip determination means of the present invention, and the functional means in step S204 is the present invention. The functional means of step S105 corresponds to the squeezing pressure gradually decreasing means of the present invention, and the functional means of steps S207 and S208 are the limit squeezing pressure detecting means of the present invention. Equivalent to.

  In the example shown in the above figure, the configuration is such that the slip in the continuously variable transmission is determined when the speed ratio change rate exceeds a predetermined threshold value. In addition to the change rate, the determination may be made based on the deviation between the actual speed ratio and the estimated speed ratio, the input rotational speed or the output rotational speed, or their bandpass filter processing values. In the above example, the configuration is such that the slip start time is detected when the speed ratio change rate exceeds the second threshold. However, the present invention is not limited to this, and the actual speed ratio change is measured. The slip start time may be detected when the deviation between the rate and the estimated gear ratio change rate exceeds a predetermined positive threshold value or negative threshold value. The estimated speed change ratio can be obtained as a value obtained by differentiating the estimated speed ratio. Furthermore, it is configured such that slip is determined based on a processing value such as a bandpass filter processing value of an input rotational speed or an output rotational speed or a bandpass filter processing value of a gear ratio, and the start time of the slip is detected. Also good.

It is a figure which shows a part of flowchart for demonstrating an example of control by the control apparatus of this invention. It is a figure which shows the part following the flowchart shown in FIG. 5 is a time chart schematically showing a relationship between an actual transmission ratio, a change ratio of a transmission ratio, and a threshold value at the time of slip determination and detection of a slip start time. It is a time chart which shows typically an example of the detection process of the limit clamping pressure by reducing clamping pressure. It is a figure which shows typically an example of the drive system containing the continuously variable transmission made into object by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 4 ... Engine (power source), 19 ... Drive pulley, 20 ... Driven pulley, 23 ... Belt, 29 ... Input shaft rotational speed sensor, 30 ... Output shaft rotational speed sensor, 31 ... For transmission Electronic control unit (CVT-ECU).

Claims (3)

The input / output member and the transmission in the continuously variable transmission that continuously changes the speed ratio by changing the torque transmission portion between the input member and the output member and the transmission member interposed between the input / output members. In a control device for a continuously variable transmission that detects slippage between members,
Slip judging means for judging the slip;
When the slip is determined by the slip determination means, the deviation between the actual change ratio of the actual speed ratio and the estimated change ratio of the estimated speed ratio before the slip or the actual change ratio of the speed ratio is positive. A control device for a continuously variable transmission, comprising: a slip start timing determining means for determining the slip start timing based on being greater than a predetermined value on the side or the negative side. The input / output member and the transmission in the continuously variable transmission that continuously changes the speed ratio by changing the torque transmission portion between the input member and the output member and the transmission member interposed between the input / output members. In a control device for a continuously variable transmission that detects slippage between members,
Slip determination means for determining the slip based on a comparison between a processing value obtained by processing at least one detection signal of a rotation speed and a gear ratio of the input member or output member and a first threshold value. When,
When the determination of the slip by the slip determination means is established, the time when the processing value first exceeds the second threshold value smaller than the first threshold value within a predetermined time width before the slip A control device for a continuously variable transmission, further comprising a slip start time determination means for determining the slip start time as the slip start time. A clamping pressure gradual decreasing means for gradually reducing a clamping pressure for setting a torque capacity between the input / output member and the transmission member and causing the slip;
Limit clamping pressure detection means for detecting a limit clamping pressure for setting the torque capacity that matches the input torque based on the clamping pressure at the slip start timing determined by the slip start timing determination means. The control device for a continuously variable transmission according to claim 1 or 2.

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