JP2005344860A - Slide detecting device of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for properly detecting a slide while avoiding influence of erroneous detection of a rotation speed in a continuously variable transmission. <P>SOLUTION: This slide detecting device of the continuously variable transmission detects the slide on the basis of a correlation coefficient between an input rotating speed and an output rotating speed; and is characterized by having a detecting abnormal value determining means (Step S203 and S403) for determining whether or not a detecting value of any rotating speed is an abnormal value, a detecting value correcting means (Step S204) for correcting the detecting value determined as abnormal on the basis of a detecting value in a period before being determined as abnormal, and a slide detecting means (Step S105, S306 and S609) for detecting the slide on the basis of the determined correlation coefficient by determining the correlation coefficient on the basis of the corrected detecting value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a slip detection device for a continuously variable transmission whose torque capacity changes in accordance with a clamping pressure.

  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 a capacity 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 that purpose, it is necessary to detect the pressure at which slipping starts (that is, the slip limit pressure). Conventionally, slip is detected by various methods, and the slip limit pressure is detected.

As an example, Patent Document 1 discloses a control device that sets a belt clamping pressure in a continuously variable transmission, calculates a correlation coefficient between an input rotation speed and an output rotation speed, and calculates the calculated correlation. An invention is described that is configured to detect belt slipping when the number falls below a threshold.
JP 2003-106442 A

  By the way, the correlation coefficient is obtained by detecting the input rotation speed and the output rotation speed with a rotation speed sensor. However, a detection error occurs due to an error in mechanical dimensions of the rotation speed sensor, disturbance at the time of detection, Numbers may be misdetected. Therefore, the calculation result of the correlation coefficient may change. As a result, when the correlation coefficient falls below a threshold value, this result may be detected as a belt slip. That is, even when the correlation coefficient fluctuates due to factors other than belt slip, there is a problem that results in detection that belt slip has occurred.

  This invention is characterized by providing a control device for a continuously variable transmission that accurately detects belt slip while eliminating the influence even if the correlation coefficient changes due to causes other than belt slip.

  In order to solve the above technical problem, even if a detected value is abnormal, it is configured to prevent erroneous detection of slippage. More specifically, the invention of claim 1 is a slip detection device for a continuously variable transmission that detects slip based on a correlation coefficient between an input rotational speed and an output rotational speed. A detected abnormal value determining means for determining whether or not the value is an abnormal value; and when the detected abnormal value determining means determines that the value is abnormal, the detected value determined to be abnormal is determined before the abnormal value is determined. Detection value correcting means for correcting based on the detected value, and slip detecting means for obtaining the correlation coefficient based on the corrected detection value and detecting slip based on the obtained correlation coefficient. It is the detection apparatus characterized by this.

  According to a second aspect of the present invention, in the first aspect of the present invention, the detected value correction means detects the detected value determined to be abnormal based on a tendency of increase or decrease of the detected value in a period before the abnormal is determined. It is the detection apparatus characterized by including the means to correct | amend.

  According to a third aspect of the present invention, in the slip detection device for a continuously variable transmission that detects slip based on the correlation coefficient between the input rotational speed and the output rotational speed, the detected value of any one of the rotational speeds is abnormal. A detection abnormal value determination unit that determines whether the value is a value, and a slip detection prohibiting unit that prohibits the detection of slip by the correlation coefficient when the detection abnormal value determination unit determines that the value is abnormal. It is the detection apparatus characterized by this.

  Furthermore, the invention of claim 4 is a slip detection device for a continuously variable transmission that detects slip on the basis of a correlation coefficient between an input rotational speed and an output rotational speed. A detection abnormal value determination means for determining whether or not a value is detected; and a determination reference value change means for changing a detection determination reference value for detection of slip by the correlation coefficient when the detection abnormal value determination means determines that there is an abnormality It is a detection apparatus characterized by comprising.

  According to the first aspect of the present invention, if the detected value of the rotational speed is an abnormal value, the detected value at the time when it is determined to be abnormal is corrected with a correction value based on the previous detected value. Then, a correlation coefficient is calculated based on the correction value, and slip determination is performed based on the change in the correlation coefficient. Therefore, even if the detection of the rotational speed is erroneously detected and the detected value becomes an abnormal value, the detected value determined to be abnormal is corrected based on the increase or decrease of the previous rotational speed change. The change of the correlation coefficient during false detection is suppressed, and slip can be detected accurately.

  According to the second aspect of the present invention, if the detected value of the rotational speed is an abnormal value, the detected value at the time when it is determined to be abnormal is corrected with a correction value based on the tendency of increase or decrease of the previous detected value. . Then, a correlation coefficient is calculated based on the correction value, and slip determination is performed based on the change in the correlation coefficient. Therefore, even if the detection of the rotational speed is erroneously detected and the detected value becomes an abnormal value, the detected value determined to be abnormal is corrected based on the increase or decrease of the previous rotational speed change. The change of the correlation coefficient during false detection is suppressed, and slip can be detected accurately.

  According to the third aspect of the present invention, if the detected value of the rotational speed is an abnormal value, the detection of slip by the correlation coefficient from the time when it is determined to be abnormal is prohibited. That is, slip detection during a period when the detected value is an abnormal value is prohibited. Therefore, it is possible to avoid the influence that the detected value becomes an abnormal value.

  Further, according to the invention of claim 4, if the detected value of the rotational speed is an abnormal value, the detection determination reference value for the detection of the slip by the correlation coefficient is changed from the time when it is determined to be abnormal. Therefore, even when the detected value becomes abnormal due to the slip and when the detected value becomes abnormal due to other than the slip, the slip can be accurately detected.

  Next, the present invention will be described based on specific examples. First, an example of a drive system including a power source and a continuously variable transmission targeted by the present invention will be described. FIG. 7 schematically shows an example of a drive system including a belt type continuously variable transmission 1. The continuously variable transmission 1 is connected to a power source 5 via a forward / reverse switching mechanism 2 and a fluid transmission mechanism 4 with a lock-up clutch 3.

  The power source 5 is composed of an internal combustion engine, or an internal combustion engine and an electric motor, or an electric motor. In the following description, the power source 5 is referred to as the engine 5. The fluid transmission mechanism 4 has a configuration similar to that of, for example, a conventional torque converter, and includes a pump impeller rotated by the engine 5, a turbine runner disposed to face the pump impeller, and a stator disposed therebetween. The turbine runner is rotated by supplying a spiral flow of fluid generated by a pump impeller to the turbine runner, and torque is transmitted.

  In such torque transmission via the fluid, inevitable slip occurs between the pump impeller and the turbine runner, and this causes a reduction in power transmission efficiency. Therefore, the input member such as the pump impeller and the turbine runner A lock-up clutch 3 that directly connects an output side member such as the above is provided. The lock-up clutch 3 is configured to be controlled by hydraulic pressure, and is controlled to a fully engaged state, a fully released state, and a slip state that is an intermediate state between them, and the slip rotation speed can be appropriately controlled. It has become.

  The forward / reverse switching mechanism 2 is a mechanism that is employed when the rotational direction of the engine 5 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. 4, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2. That is, a ring gear 7 is arranged concentrically with the sun gear 6, and a pinion gear 8 meshed with the sun gear 6 and the pinion gear 8 and another pinion gear 9 meshed with the ring gear 7 are arranged between the sun gear 6 and the ring gear 7. The pinion gears 8 and 9 are held by the carrier 10 so as to rotate and revolve freely. A forward clutch 11 that integrally connects two rotating elements (specifically, the sun gear 6 and the carrier 10) is provided, and the direction of the torque that is output by selectively fixing the ring gear 7 There is provided a reverse brake 12 that reverses.

  The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and each of a driving pulley 13 and a driven pulley 14 arranged in parallel to each other includes a fixed sheave, a hydraulic type The movable sheave is moved back and forth in the axial direction by the actuators 15 and 16. Therefore, the groove width of each pulley 13 and 14 is changed by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 17 wound around each pulley 13 and 14 (the effective diameter of the pulleys 13 and 14). ) Changes continuously, and the gear ratio changes steplessly. The drive pulley 13 is connected to a carrier 10 that is an output element in the forward / reverse switching mechanism 2.

  The hydraulic actuator 16 in the driven pulley 14 is supplied with 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 14 holds the belt 17 so that tension is applied to the belt 17, and a holding pressure (contact pressure) between the pulleys 13, 14 and the belt 17 is ensured. . On the other hand, the hydraulic actuator 15 in the drive pulley 13 is supplied with pressure oil corresponding to the speed ratio to be set, and is set to a groove width (effective diameter) corresponding to the target speed ratio. .

  The driven pulley 14 is connected to a differential 19 through a gear pair 18, and torque is output from the differential 19 to driving wheels 20. Therefore, in the above drive mechanism, the lockup clutch 3 and the continuously variable transmission 1 are arranged in series between the engine 5 and the drive wheels 20.

  Various sensors are provided to detect the operating state (running state) of the vehicle on which the continuously variable transmission 1 and the engine 5 are mounted. That is, a turbine rotation speed sensor 21 that detects an input rotation speed (rotation speed of the turbine runner) to the continuously variable transmission 1 and outputs a signal, and an input rotation speed that detects the rotation speed of the drive pulley 13 and outputs a signal. A sensor 22, an output rotation speed sensor 23 that detects the rotation speed of the driven pulley 14 and outputs a signal, and a hydraulic pressure sensor 24 that detects the pressure of the hydraulic actuator 16 on the driven pulley 14 side for setting the belt clamping pressure are provided. ing. Although not specifically shown, an accelerator opening sensor that detects a depression amount of the accelerator pedal and outputs a signal, a throttle opening sensor that detects a throttle valve opening and outputs a signal, and a brake pedal are depressed. In this case, a brake sensor for outputting a signal is provided.

  A transmission is used to control the engagement / release of the forward clutch 11 and the reverse brake 12, the control of the clamping force of the belt 17, the control of the transmission ratio, and the control of the lockup clutch 3. An electronic control device (CVT-ECU) 25 is provided. The transmission electronic control unit 25 is configured mainly by a microcomputer as an example, and performs calculations according to a predetermined program based on input data and data stored in advance, and performs various operations such as forward, reverse, or neutral. And the required clamping pressure setting, the gear ratio setting, the engagement / release of the lock-up clutch 3, the slip rotation speed, and the like are executed.

  Here, an example of data (signal) input to the transmission electronic control unit 25 is as follows: a signal of the input rotation speed (input rotation speed) Nin of the continuously variable transmission 1 and an output of the continuously variable transmission 1. A signal of the rotational speed (output rotational speed) No is input from the corresponding sensor. Further, an engine electronic control unit (E / G-ECU) 26 that controls the engine 5 receives a signal of an engine speed Ne, an engine (E / G) load signal, a throttle opening signal, an accelerator pedal (not shown). )), The accelerator opening signal is input.

  According to the continuously variable transmission 1, the engine speed, which is the input speed, can be controlled steplessly (in other words, continuously), so that the fuel efficiency of a vehicle equipped with the engine speed can be improved. For example, the target driving force is obtained based on the required driving amount represented by the accelerator opening and the vehicle speed, and the target output necessary to obtain the target driving force is obtained based on the target driving force and the vehicle speed. The engine speed for obtaining the target output with the optimum fuel consumption is obtained based on a map prepared in advance, and the gear ratio is controlled so as to be the engine speed.

  In order not to impair such an improvement in fuel consumption, the power transmission efficiency in the continuously variable transmission 1 is controlled to a good state. Specifically, the torque capacity of the continuously variable transmission 1, that is, the belt clamping pressure, can transmit the target torque determined based on the engine torque, and the belt clamping pressure is as low as possible without causing the belt 17 to slip. It is controlled to become. For example, the belt clamping pressure controls the continuously variable transmission 1 in a so-called unsteady traveling state such as when acceleration / deceleration is performed relatively frequently or when traveling on a rough road with uneven or uneven road surfaces. It is set to a relatively high pressure such as the line pressure that is the total source pressure in the hydraulic system or its correction pressure.

  On the other hand, in steady running conditions such as running on a flat road at a certain speed or above, or in a quasi-steady running condition equivalent to this, the lowest pressure that can transmit input torque without slipping, that is, the limit clamping pressure In order to detect this, the belt clamping pressure is gradually reduced. The belt clamping pressure is set to a belt clamping pressure obtained by adding a predetermined safety factor or a pressure for setting a margin transmission torque for slipping to the detected limit clamping pressure. The belt clamping pressure in the continuously variable transmission is preferably as low as possible within a range where torque can be transmitted without causing slippage. Therefore, it is necessary to detect belt slip in order to obtain the limit clamping pressure.

  As an example of detecting belt slip, when the belt slips, the ratio of the input rotation speed and the output rotation speed changes, so the change in the rotation speed ratio changes the correlation coefficient between the input rotation speed and the output rotation speed. You may ask as The belt clamping pressure is set as low as possible within a range in which the change in the correlation coefficient does not become larger than a preset value. However, the rotational speed sensor that obtains the input rotational speed or output rotational speed may be erroneously detected due to the influence of disturbance, etc., and if the rotational speed sensor detects it incorrectly, the correlation coefficient changes due to factors other than belt slippage. Will do. Therefore, even if the belt does not slip, the correlation coefficient changes, and it may be determined that the belt has slipped. Therefore, the following control is performed in order to avoid the influence due to the change of the correlation coefficient when the erroneous detection of the rotation speed sensor occurs.

  Note that a routine for executing the following control is periodically executed at predetermined time intervals. The “false detection” described here means that the detection value by the rotation speed sensor does not reflect the actual rotation speed due to the influence of factors other than slip such as disturbance, that is, the detection value indicates an abnormal value. Specifically, it appears as a phenomenon such as a rapid fluctuation of the detected value. Therefore, it is possible to determine whether or not it is “false detection” by detecting a sudden change in these detection values.

  FIG. 1 is a flowchart showing an example of belt slip detection control that avoids the influence of a change in correlation coefficient when erroneous detection of the rotation speed sensor occurs. First, it is determined whether a start condition is satisfied (step S101). This start condition is that the vehicle speed is within a predetermined range, the shift command value is within a predetermined range, and a sufficient time has passed to detect the number of rotation speed data necessary for calculation associated with the control. This is established when all the conditions such as the normality of the rotation speed sensor are satisfied at the start of the control.

  When the start condition is satisfied, the input rotational speed Nin (i) and the output rotational speed Nout (i) at the current time are detected (step S102). Then, predetermined control 1 is executed (step S103). The predetermined control 1 is a routine for determining whether or not there is an erroneous detection in the rotational speed detection and correcting the detected value when there is an erroneous detection. Details will be described later.

  When the detection value is corrected in step S103, a correlation coefficient k (i) is obtained using a series of detection values including the detection value corrected in step S103 (step S104). Then, it is determined whether or not the correlation coefficient k (i) is smaller than the threshold value kslp (step S105). The threshold value kslp is a map value obtained from the gear ratio and the vehicle speed.

  If the determination in step S105 is affirmative, that is, if the correlation coefficient k (i) is smaller than the threshold kslp, it is determined that belt slip has occurred (step S106). Control corresponding to the occurrence of belt slip is performed (step S107).

  On the other hand, when a negative determination is made in step S101, that is, when the start condition is not yet satisfied, or when a negative determination is made in step S105, that is, the correlation coefficient k (i) is a threshold value. If it is smaller than kslp, normal clamping pressure control is performed (step S108).

  Next, the predetermined control 1 will be described with reference to FIG. First, an output correction value Noutave (i) is obtained from the previous detection value detected at the time of execution of the previous routine and the moving average value of the change gradient before a predetermined time (step S201). Specifically, a value obtained by adding the previous detection value to the moving average value of the change gradient is the output correction value Noutave (i). Therefore, the current correction value reflecting the change tendency of the output rotational speed can be obtained by adding the moving average of the change gradient of the output rotational speed Nout up to a predetermined time to the previous value. In step S201, the average value of the change gradient is obtained based on the detected value from the present four cycles before, but the length of the section for obtaining the average value of the change gradient can be arbitrarily set. it can.

  When the output correction value Noutave (i) is obtained in step S201, an upper limit threshold value Nplsmax (i) and a lower limit threshold value Nplsmin (i) based on the output correction value Noutave (i) are obtained (step S202). . The upper threshold value Nplsmax (i) and the lower threshold value Nplsmin (i) are map values obtained from the output correction value Noutave (i).

  When the upper threshold value Nplsmax (i) and the lower threshold value Nplsmin (i) are obtained, the amount of change in the output speed exceeds the upper threshold value Nplsmax (i), or the lower threshold value Nplsmin It is determined whether it is below (i) (step S203). Specifically, is the difference between the current detection value Nout (i) and the previous value Nout (i-1) higher than the upper threshold Nplsmax (i) or lower than the lower threshold Nplsmin (i)? Judging. This is because if the detection value changes due to erroneous detection of the rotational speed sensor, a rapid change occurs in a short time, so if the change during the latest one cycle time exceeds a predetermined value, the erroneous detection of the rotational speed sensor It is because it can be considered.

  If the determination in step S203 is affirmative, that is, the difference between the current detection value Nout (i) and the previous value Nout (i-1) exceeds the upper threshold value Nplsmax (i), or the lower limit threshold value. If the value is lower than the value Nplsmin (i), the output correction value Noutave (i) is set as the current detection value Nout (i) (step S204), and the process returns. If the determination in step S203 is negative, the process returns without performing any particular processing.

  Therefore, if the detected value Nout of the output rotation number is an abnormal value, the detected value Nout (i) at the time when it is determined to be abnormal is changed from the previous detected value Nout (i-1) to Nout (i-4). It is corrected with the correction value Noutave (i) obtained from the increase / decrease tendency. Then, the correlation coefficient k (i) is calculated based on the correction value Noutave (i), and the slip determination is performed based on the change in the correlation coefficient k (i). Therefore, even if the detection of the rotational speed is erroneously detected and the detected value becomes an abnormal value, the rotational speed Nout (i) during the erroneous detection period is equal to the rotational speed detected value Nout (i) during the previous period. Since the correction is performed based on the increase / decrease of the change from -1) to Nout (i-4), the change of the correlation coefficient k (i) during the false detection is suppressed, and the slip can be accurately detected.

  In the above-described embodiment, the present invention can be applied when erroneous detection occurs in a single shot, but it can also be configured to stop slip detection during the erroneous detection occurrence period when erroneous detection occurs continuously. . FIG. 3 is a flowchart showing the control.

  First, the input rotation speed Nin (i) and the output rotation speed Nout (i) at the current time are detected (step S301). Then, it is determined whether or not the start condition is satisfied (step S302). This start condition is that the vehicle speed is within a predetermined range, the shift command value is within a predetermined range, and a sufficient time has passed to detect the number of rotation speed data necessary for calculation associated with the control. This is established when all the conditions such as the normality of the rotation speed sensor are satisfied at the start of the control.

  When the start condition is satisfied in step S302, predetermined control 2 is executed (step S303). This predetermined control 2 is a routine for determining whether or not there has been a false detection in the rotational speed detection. Details will be described later.

  If an erroneous detection is determined in step S303, it is determined whether or not the counter cnt (i) is smaller than a preset set value start_cnt (step S304). The counter cnt (i) is a counter that continues to be counted when the rotational speed is normally detected by the predetermined control 2. That is, in this step S304, it is determined whether or not the period during which the rotation speed is normally detected continues to some extent.

  If the determination in step S304 is affirmative, that is, if it is determined that the counter cnt (i) is smaller than the set value start_cnt, it is considered that sufficient data is not accumulated to obtain the correlation coefficient. Therefore, normal clamping pressure control is performed (step S308), and then predetermined control 3 is performed (step S309). Predetermined control 3 is a routine that determines whether or not erroneous detection has continued, and determines whether or not to stop slip detection control when it is determined that erroneous detection has continued. Details of the predetermined control 3 will be described later.

  On the other hand, when a negative determination is made in step S304, that is, when it is determined that the counter cnt (i) is larger than the set value start_cnt, data sufficient to obtain the correlation coefficient is accumulated. Therefore, a correlation coefficient is obtained from the detected value data of the latest N (N is an arbitrary number) input rotation speed and output rotation speed (step S305). Then, it is determined whether or not the obtained correlation coefficient is smaller than the threshold value kslp (step S306). The threshold value kslp is a map value obtained from the gear ratio and the vehicle speed.

  If the determination in step S306 is affirmative, that is, if the correlation coefficient k (i) is smaller than the threshold kslp, it is determined that belt slip has occurred, and belt slip such as an increase in pinching pressure has occurred. Corresponding control is performed (step S307), and then predetermined control 3 is performed (step S309). Then, after the predetermined control 3 is performed, the routine is exited.

  On the other hand, when a negative determination is made in step S302, that is, when the start condition is not yet satisfied, or when a negative determination is made in step S306, that is, the correlation coefficient k (i) is a threshold value. If it is smaller than kslp, normal clamping pressure control is performed (step S308), and then predetermined control 3 is performed (step S309). Then, after the predetermined control 3 is performed, the routine is exited.

  Next, the predetermined control 2 will be described. A flowchart of the predetermined control 2 is shown in FIG. Predetermined control 2 is basically the same as predetermined control 1, and the processes for steps S401, S402, and S403 are the same as steps S201, S202, and S203 in predetermined control 1, respectively.

  The processing after step S403 is different between the predetermined control 1 and the predetermined control 2. If the determination in step S403 is negative, that is, if it is determined that there is no false detection, the counter cnt (i) is incremented (step S405). Then, the routine of the predetermined control 2 is exited. If the determination in step S403 is affirmative, that is, if it is determined that there is a false detection, the counter cnt (i) is set to zero and the routine of predetermined control 2 is exited.

  Thereby, in the routine executed following the predetermined control 2, it is possible to determine whether or not it is a false detection based on the value of the counter cnt (i). That is, when it is determined that the counter cnt (i) is smaller than the set value start_cnt, it is determined that sufficient normal data for obtaining the correlation coefficient is not accumulated (determination in step S304). . On the other hand, if it is determined that the counter cnt (i) is greater than or equal to the set value start_cnt, it is determined that sufficient normal data is stored to obtain the correlation coefficient (determination in step S304).

  Next, the predetermined control 3 will be described using the flowchart of FIG. Predetermined control 3 is a routine that determines whether or not erroneous detection has continued, and determines whether or not to stop slip detection control when it is determined that erroneous detection has continued. First, it is determined whether or not the counter cnt (i) is zero (step S501). That is, it is determined whether or not the rotational speed is erroneously detected. If the rotational speed sensor is not erroneously detected at the beginning of control, the counter cnt (i) is “1” in step S405, and thus a negative determination is made in step S501. Then, it is determined whether or not the error counter error_cnt is zero (step S505). Since the error counter error_cnt indicating the number of erroneous detections is zero at the beginning of the control, the determination in step S505 is affirmative. If an affirmative determination is made in step S505, this routine is exited without performing any particular processing.

  If the time has elapsed and the rotational speed sensor is erroneously detected, an affirmative determination is made in step S403, and the counter cnt (i) is set to zero in step S404. Therefore, an affirmative determination is made in step S501, and an error counter error_cnt indicating the number of erroneous detections is incremented (step S502). Then, it is determined whether or not the error counter error_cnt is larger than the predetermined value errormax and the time counter time_cnt indicating the length of the erroneous detection period is smaller than the predetermined value timemax (step S503). Since the error counter error_cnt is naturally smaller than errormax at the time of execution of the first routine in which erroneous detection occurs, a negative determination is made in step S503.

  If a negative determination is made in step S503, the error counter error_cnt is greater than zero, so a negative determination is made in step S505. Then, it is determined whether or not the time counter time_cnt is greater than a predetermined value timemax (step S506). Since the initial time counter time_cnt is smaller than the predetermined value timemax, a negative determination is made in step S506, and the time counter time_cnt is incremented (step S508). Then, this routine is exited. Thereafter, this routine is continued until the error counter error_cnt exceeds a predetermined value errormax, that is, until the erroneous detection period exceeds a predetermined time. That is, the time counter time_cnt and the error counter error_cnt are continuously incremented in step S508 until the determination in step S503 or step S506 is positively established.

  If erroneous detection continues and the error counter error_cnt exceeds the predetermined value errormax, an affirmative determination is made in step S503, and slip detection control is stopped (step S504). Then, this routine is exited. Thereafter, when there is no false detection, a negative determination is made in step S403, and the counter cnt (i) is incremented in step S405. Then, a negative determination is made in step S501, but since the error counter error_cnt is not zero, a negative determination is made in step S505. Since the time counter time_cnt does not exceed the predetermined value timemax, a negative determination is made in step S506, the time counter time_cnt is incremented in step S508, and the routine is exited.

  Thereafter, when time elapses and the time counter time_cnt reaches or exceeds the predetermined value timemax, an affirmative determination is made in step S506, the error counter error_cnt and the time counter time_cnt are cleared to zero (step S507), and the routine Exit.

  Accordingly, whether or not the detected value of the rotational speed is abnormal is determined in step S403, and if it is an abnormal value, it is determined that the detection is false, and if false detection continues, that is, positively in step S503. When it is determined, slip detection control from the time point when it is determined that the detection error is detected is prohibited. That is, slip detection during erroneous detection is prohibited. Therefore, slip detection can be performed without being affected by erroneous detection.

  By the way, when erroneous detection and slip occur at the same time, in addition to a decrease in correlation coefficient due to erroneous detection, a decrease in correlation coefficient due to slip is added. Therefore, it is necessary to use a threshold value that is lower than the threshold value when no false detection is performed for slip detection determination. However, if the threshold value is kept low, false detection and slip occur simultaneously. If not, slip determination may not be performed properly. Therefore, when such erroneous detection and slip occur at the same time, the threshold value may be switched. That is, in the above embodiment, only one threshold value for detecting belt slip is set, but a plurality of threshold values may be set. FIG. 6 is a flowchart showing a control example in which two threshold values are set.

  First, it is determined whether a start condition is satisfied (step S601). The starting conditions are that the vehicle speed is within a predetermined range, that the shift command value is within a predetermined range, and that a sufficient amount of time has elapsed to detect the number of rotation speed data necessary for calculation associated with the control. And the fact that the rotational speed sensor is all normal at the start of the control.

  When the start condition is satisfied, the current input rotational speed Nin (i) and the output rotational speed Nout (i) are detected (step S602). Then, predetermined control 2 is executed (step S603). The predetermined control 2 is the same control as the above-described steps S401 to S405. Then, a correlation coefficient is obtained from the detected value data of the latest N (N is an arbitrary number) input rotation speed and output rotation speed (step S604). Further, it is determined whether or not the counter cnt (i) is smaller than a preset set value start_cnt (step S605). The counter cnt (i) is a counter that continues to be counted when the rotational speed is normally detected by the predetermined control 2. That is, in this step S605, it is determined whether or not the period during which the rotation speed is normally detected continues to some extent.

  If the determination in step S605 is affirmative, that is, if it is determined that the counter cnt (i) is smaller than the set value start_cnt, that is, whether a false detection has occurred or even after recovery from the false detection. If it is determined that there is no threshold value, the threshold value kslp is set to a predetermined value kslp2 (step S607). The predetermined value kslp2 is a map value obtained from the correction value Noutave calculated in the predetermined control 2, and is smaller than the predetermined value kslp1 selected in the normal state.

  On the other hand, if a negative determination is made in step S304, that is, if it is determined that the counter cnt (i) is larger than the set value start_cnt, in other words, whether a false detection has occurred or the false detection has occurred. If it is determined that sufficient time has passed since the recovery, the threshold value kslp is set to a predetermined value kslp1 (step S608). The predetermined value kslp1 is a map value obtained from the gear ratio and the vehicle speed.

  Then, it is determined whether or not the obtained correlation coefficient is smaller than the threshold value kslp (step S609). If the determination in step S609 is affirmative, that is, if the correlation coefficient k (i) is smaller than the threshold value kslp, it is determined that belt slip has occurred, and belt slip such as increase in pinching pressure has occurred. Corresponding control is performed (step S610), and this routine is exited. On the other hand, if a negative determination is made in step S609, the routine is exited after normal clamping pressure control is performed (step S611).

  Therefore, if the detected value of the rotational speed is an abnormal value, the detection determination reference value serving as the threshold for detecting slip is changed from the time when it is determined as abnormal. Therefore, even when slipping and erroneous detection occur at the same time, it is possible to accurately detect slipping.

  Here, the relationship between each of the above specific examples and the present invention will be briefly described. The functional means of step S203 and step S403 correspond to the “detected abnormal value determining means” in the present invention, and the functional means of step S204. Corresponds to “detected value correcting means” in the present invention. Further, the functional means of step S105, step S306, and step S609 correspond to the “slip detection means” in the present invention, and the functional means of step S504 corresponds to the “slip detection prohibition means” in the present invention. The functional means in step S607 and step S608 correspond to the “judgment reference value changing means” in the present invention, and the functional means in step S201 and step S202 correspond to the “increase / decrease tendency correcting means” in the present invention. Further, any one of the threshold value kslp, the predetermined value kslp1, and the predetermined value kslp2 corresponds to the “detection judgment reference value” in the present invention.

  In addition, this invention is not limited to the said Example. That is, in the above embodiment, the belt type continuously variable transmission has been described. However, this may be applied to a traction type continuously variable transmission. In short, the present invention can be applied to a continuously variable transmission in which the torque capacity to be transmitted can be made variable by controlling the clamping pressure.

It is a flowchart for demonstrating an example of control by the control apparatus of this invention. 3 is a flowchart for explaining a predetermined control 1; It is a flowchart for demonstrating the other example of control by the control apparatus of this invention. 5 is a flowchart for explaining predetermined control 2; 5 is a flowchart for explaining predetermined control 3; It is a flowchart for demonstrating the 3rd example of control by the control apparatus of this invention. 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, 5 ... Engine (power source), 13 ... Drive pulley, 14 ... Driven pulley, 15, 16 ... Hydraulic actuator, 17 ... Belt, 25 ... Electronic control unit for transmission (CVT-ECU).

Claims (4)

In a continuously variable transmission slip detection device that detects slip based on a correlation coefficient between an input rotational speed and an output rotational speed,
A detection abnormal value determination means for determining whether or not the detection value of any of the rotation speeds is an abnormal value;
A detection value correction unit that corrects the detection value determined to be abnormal based on the detection value in a period before the abnormality is determined when the detection abnormal value determination unit determines that the abnormality has occurred;
A slip detection device for a continuously variable transmission, comprising: a slip detection unit that calculates the correlation coefficient based on the corrected detection value and detects a slip based on the calculated correlation coefficient.   The detection value correction means includes means for correcting the detection value determined to be abnormal based on a tendency of increase / decrease of the detection value in a period before it is determined to be abnormal. The slip detection device for a continuously variable transmission according to claim 1. In a continuously variable transmission slip detection device that detects slip based on a correlation coefficient between an input rotational speed and an output rotational speed,
A detection abnormal value determination means for determining whether or not the detection value of any of the rotation speeds is an abnormal value;
A slip detection device for a continuously variable transmission, comprising: slip detection prohibiting means for prohibiting detection of slip based on the correlation coefficient when the detected abnormal value determining means determines an abnormality. In a continuously variable transmission slip detection device that detects slip based on a correlation coefficient between an input rotational speed and an output rotational speed,
A detection abnormal value determination means for determining whether or not the detection value of any of the rotation speeds is an abnormal value;
A continuously variable transmission comprising: a determination reference value changing means for changing a detection determination reference value for detecting slip by the correlation coefficient when the detection abnormal value determination means determines an abnormality. Slip detection device.

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