JP2005048854A - Controller for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller capable of determining a slide start point of a continuously variable transmission by tracing back in the past from slide detection time and by taking an operation condition of a vehicle into account to detect slide or slide limit nipping pressure precisely. <P>SOLUTION: This controller for the continuously variable transmission detects relative slide among an input member and an output member and a transmission member for transmitting power between these input and output members and determines a predetermined point as the slide start point by tracing back in the past from the slide detection point. This controller is provided with a plurality of kinds of slide start point determining means for determining the slide start point by tracing back in the past from the slide detection point (steps S106, S107, S109, S110), operation condition detection means for detecting an operation condition of the vehicle on which the continuously variable transmission is mounted (steps S104, S105, S108), and selection means for selecting the slide start point determining means based on the detected operation condition (steps S108 to S110). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for a continuously variable transmission whose torque capacity changes in accordance with the clamping pressure, and more particularly to a control device configured to detect a slip limit pressure by reducing the 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 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 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.

  One example is a slip detection method for a continuously variable transmission that transmits power through frictional contact or its transmission system, and it is accompanied by a reduction in pressure-bonding force (ie, pinching pressure or engagement pressure). Patent Document 1 describes a method of determining slip by detecting an increase in friction efficiency (specifically, an increase in oil temperature). In the method described in Patent Document 1, the slip limit is determined by gradually reducing the pressure-bonding force in a state where the transmission force, speed, or transmission ratio is substantially constant, and then the slip limit does not exist or is specified in advance. The crimping force is adjusted so that the slip limit value is not exceeded.

Further, Patent Document 2 detects the presence or absence of belt slip by comparing the actual gear ratio change rate and the theoretical gear change rate in a belt type continuously variable transmission, and if belt slip is detected, the line pressure is detected. An apparatus configured to increase the is described.
JP 2001-12593 A JP-A-6-11022

  In the invention of the above-mentioned Patent Document 1, slip detection is performed based on an increase in friction efficiency. The friction efficiency is, for example, oil temperature, and therefore, until slip is actually detected until slip is detected. It takes time and not only the detection accuracy of slip is low, but also the detection accuracy of the slip limit clamping pressure is deteriorated. Further, as described in Patent Document 2, if slip is detected based on the speed change rate, detection delay can be eliminated to some extent. However, since the actual transmission ratio detection value varies due to various factors other than slipping, the deviation from the theoretical gear change rate becomes large to some extent, and the judgment of slipping is established. In addition, the detection accuracy may be reduced.

  The present invention has been made paying attention to the above technical problem, and by determining the slip start time of the continuously variable transmission retroactively from the time of slip detection and taking into consideration the driving state of the vehicle. An object of the present invention is to provide a control device that can accurately detect slippage or slip limit clamping pressure.

  In order to achieve the above object, the present invention sets a plurality of slip start time determination means for determining a slip start time retroactively from the time of slip detection, and determines the slip start time determination means according to the driving state of the vehicle. Is selected to determine the slip start time. That is, the invention according to claim 1 detects relative slip between the input / output member and the transmission member that transmits power between these input / output members, and from the time when the slip is detected to the past. A control device for a continuously variable transmission that determines a predetermined point in time as a slip start point, and a plurality of types of slip start point determination means for determining a slip start point retroactively from the slip detection point, A control apparatus comprising: a driving state detection unit that detects a driving state of a vehicle equipped with a step transmission; and a selection unit that selects the slip start time determination unit based on the detected driving state. It is.

  According to the first aspect of the present invention, when the start time of the slip of the continuously variable transmission is determined retroactively from the time when the slip is detected, a plurality of types of slip start are determined according to the running state of the vehicle. An appropriate determination means is selected from the time determination means and determined. Therefore, it is possible to accurately determine the start point of the slip, reflecting various driving states of the vehicle such as a slip occurrence state in the continuously variable transmission.

  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 in the present invention will be described. FIG. 4 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 through the fluid, inevitable slip occurs between the pump impeller and the turbine runner, which 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 in order to detect the operation state (running state) of the vehicle on which the continuously variable transmission 1 and the engine 5 are mounted. That is, the turbine speed sensor 21 that detects the input speed (the speed of the turbine runner) to the continuously variable transmission 1 and outputs a signal, and the input speed that detects the speed of the drive pulley 13 and outputs the 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. A brake sensor or the like that outputs a signal in case 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 electronic control unit 25 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, it is configured to execute control such as setting of a required clamping pressure, setting of a gear ratio, engagement / release of the lock-up clutch 3, and slip rotation speed.

  Here, an example of data (signals) input to the transmission electronic control unit 25 is shown. A signal of the input rotational speed (input rotational speed) Nin of the continuously variable transmission 1, an output of the continuously variable transmission 1. A signal of the rotational speed (output rotational speed) No is inputted from the corresponding sensor. An engine electronic control unit (E / G-ECU) 26 for controlling 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.

  Thus, 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, the control device of the present invention reduces the belt clamping pressure, detects the resulting slip, obtains the critical clamping pressure, sets the clamping pressure based on the critical clamping pressure, and converges the slip. The input torque is configured to decrease in cooperation with the clamping pressure control.

  The slip in the present invention is, for example, a comparison between an actual transmission ratio that represents an actual change in the transmission ratio of the continuously variable transmission and an estimated transmission ratio that is estimated from the actual transmission ratio in a state without slippage before the slip is detected. Thus, the detection determination is performed, and the slip start time is specified retroactively from the slip detection time based on the slip detection result, the estimated gear ratio, and the like. Further, the limit clamping pressure is obtained by setting the clamping pressure at the start of the slip as the limit clamping pressure. Therefore, whether or not the estimated speed ratio is estimated accurately affects the detection of slip and determination of the start time of slip, that is, the setting of the limit clamping pressure or the setting of the input torque to be reduced. Therefore, the control device of the present invention is configured to improve the estimation accuracy of the estimated gear ratio. A specific example of the control will be described below.

FIG. 1 is a flowchart showing an example. In FIG. 1, first, the current input / output shaft rotational speeds Nin (i) and Nout (i) are measured. From these Nin (i) and Nout (i), the actual speed ratio which is the current actual speed ratio. γ and an actual shift speed Δγ (i), which is a change amount of the actual gear ratio γ (i), are calculated (step S101). That is, the actual transmission ratio γ (i) and the actual transmission speed Δγ (i) are calculated from the rotational speeds Nin (i) and Nout (i) and the previous actual transmission ratio γ (i-1), respectively.
γ (i) = Nin (i) / Nout (i)
Δγ (i) = γ (i) −γ (i-1)
Can be calculated as

  Subsequently, it is determined whether or not the limit clamping pressure detection control is being executed (step S102). The limit clamping pressure detection control is control for reducing the clamping pressure of the continuously variable transmission 1 and detecting the slip at that time, and specifying the slip start time based on the detection result to obtain the limit clamping pressure. . If it is determined negative in step S102 because the limit clamping pressure detection control is not being executed, the process proceeds to step S112, where the state counter value C1 before limit clamping pressure detection is reset to zero, and the limit clamping pressure detection flag F1. Is set to “0” (step S113). Thereafter, this routine is once terminated.

  On the other hand, if the determination in step S102 is affirmative because the limit clamping pressure detection control is being executed, the process proceeds to step S103, and whether or not the previous value of the limit clamping pressure detection flag F1 is “0”. Is judged. The limit clamping pressure detection flag F1 is set to “0” when the limit clamping pressure detection control is not being executed as described above, and is set to “1” when the limit clamping pressure detection control is being executed. Initially set to “0”. Therefore, if the previous value of the limit clamping pressure detection flag F1 is initially “0” and a positive determination is made in step S103, the process proceeds to step S104, and the actual transmission speed Δγ ( It is determined whether or not the absolute value of i) is greater than a limit clamping pressure pre-detection state determination threshold value Δγt1.

  The limit clamping pressure pre-detection state determination threshold value Δγt1 represents an actual transmission speed Δγ as shown in “in the case of the estimated transmission ratio calculation method 1” and “in the case of the estimated transmission ratio calculation method 2” in the time chart of FIG. This is a threshold value that serves as a reference for identifying various slippage occurrence states of the continuously variable transmission 1 before the limit clamping pressure detection determination by comparing the states of the vibrational changes in the diagrams.

  If the absolute value of the actual shift speed Δγ (i) is greater than the limit clamping pressure pre-detection state determination threshold value Δγt1 and the determination is affirmative in step S104, the process proceeds to step S105, and the limit clamping pressure pre-detection state counter is reached. After the value C1 is incremented, the process proceeds to step S106. Further, if the absolute value of the actual shift speed Δγ (i) is equal to or less than the limit clamping pressure pre-detection state determination threshold value Δγt1, if a negative determination is made in step S104, step S105 is skipped, that is, the limit clamping is performed. The pre-pressure detection state counter value C1 is not incremented, and the process proceeds to step S106.

  In step S106, it is determined whether or not the absolute value of the actual shift speed Δγ (i) is greater than the limit clamping pressure detection determination threshold value Δγt2. That is, it is determined whether or not the limit clamping pressure detection determination is established based on whether or not the absolute value of the actual shift speed Δγ (i) exceeds the limit clamping pressure detection determination threshold value Δγt2.

  If the absolute value of the actual shift speed Δγ (i) is less than or equal to the limit clamping pressure detection determination threshold Δγt2 and is negatively determined in step S106, that is, if the limit clamping pressure has not yet been detected, step Proceeding to S113, the limit clamping pressure detection flag F1 is set to “0”. Thereafter, this routine is once terminated. On the other hand, if the absolute value of the actual shift speed Δγ (i) is greater than the limit clamping pressure detection determination threshold Δγt2 and is affirmed in step S106, that is, if the limit clamping pressure is detected, step Proceeding to S107, the limit clamping pressure detection flag F1 is set to “1”.

  On the other hand, if the previous value of the limit clamping pressure detection flag F1 is not “0” and a negative determination is made in step S103, the subsequent steps S104 to S106 are skipped and the process proceeds to step S107. The current limit clamping pressure detection flag F1 is set to “1”. That is, if the limit clamping pressure detection control is being executed continuously from the previous time, the state counter value C1 before the limit clamping pressure detection is not incremented, and the determination of the absolute value of the actual shift speed Δγ (i) is not made. Without proceeding to step S107, the current limit clamping pressure detection flag F1 is set to "1".

  When the current limit clamping pressure detection flag F1 is set to “1” in step S107, the process proceeds to step S108, and it is determined whether or not the state counter value C1 before detection of the limit clamping pressure is greater than the estimated speed ratio selection threshold Ct. Is done. This counts the frequency at which the absolute value of the actual shift speed Δγ (i) does not exceed the limit clamping pressure detection determination threshold Δγt2 but exceeds the pre-limit clamping pressure detection condition determination threshold Δγt1, and the frequency (that is, limit clamping pressure detection) This is control for selecting an appropriate one of a plurality of estimated speed ratio calculation methods according to the previous state counter value C1).

  Therefore, if the state counter value C1 before the limit clamping pressure detection is equal to or less than the estimated transmission ratio selection threshold Ct, the negative value is determined in step S108, that is, the absolute value of the actual transmission speed Δγ (i) is the limit. When the frequency of exceeding the pre-clamping pressure detection state determination threshold Δγt1 is low, the process proceeds to step S109, and the routine of the estimated speed ratio calculation method 2 shown in FIG. Further, when the state counter value C1 before the limit clamping pressure detection is larger than the estimated transmission ratio selection threshold Ct, if the determination in step S108 is affirmative, that is, the absolute value of the actual transmission speed Δγ (i) is the limit. If the clamping pressure detection determination threshold Δγt2 does not exceed the limit clamping pressure pre-detection state determination threshold Δγt1, the routine proceeds to step S110, and the routine of the estimated gear ratio calculation method 1 shown in FIG. Is done.

  Here, the case where the frequency at which the absolute value of the actual speed change Δγ (i) exceeds the limit clamping pressure pre-detection state determination threshold value Δγt1 is low is shown in “time of estimated speed ratio calculation method 2” in the time chart of FIG. In such a state, there is a period in which the actual shift speed Δγ (i) exhibits a fine slip or a sign of a slip that is expressed as a small amplitude that does not exceed the limit clamping pressure pre-detection state determination threshold Δγt1. This is a case where the state is short and thereafter the amplitude becomes large at a stroke and starts to slide. In such a case, a period for obtaining an estimated speed ratio calculation gradient for calculating an estimated speed ratio, which will be described later, is traced back a predetermined time from the time when the limit clamping pressure detection determination is established (in this case, periods A and B in FIG. 3). ) Can calculate the estimated gear ratio calculation gradient with higher accuracy when set shorter.

  In addition, when the absolute value of the actual shift speed Δγ (i) does not exceed the limit clamping pressure detection determination threshold Δγt2 but frequently exceeds the limit clamping pressure detection state determination threshold Δγt1, the time chart of FIG. In the state shown in “In the case of the estimated transmission ratio calculation method 1”, the actual transmission speed Δγ (i) does not exceed the limit clamping pressure detection determination threshold Δγt2, but exceeds the limit clamping pressure pre-detection state determination threshold Δγt1. This is a case in which a period of slipping or a sign of slipping, which is expressed as an amplitude of, continues for a relatively long period of time, and then the amplitude becomes large and starts to slip. In such a case, periods (in this case, periods α and β in FIG. 3) for obtaining an estimated gear ratio calculation gradient, which are traced back a predetermined time from when the limit clamping pressure detection determination is established, are the periods A and B described above. The estimated speed ratio calculation gradient can be calculated with higher accuracy by setting a longer time.

  As described above, the state determination threshold value Δγt1 before the limit clamping pressure is provided, the operation state of the continuously variable transmission 1 before the limit clamping pressure is detected is determined, and the estimated speed ratio is determined based on the determination result. By appropriately selecting the calculation method and calculating the estimated gear ratio, the estimated gear ratio is calculated by an appropriate calculation method corresponding to various operating states of the continuously variable transmission 1 in accordance with changes in the driving state and the running state of the vehicle. It is possible to calculate, and the estimation accuracy of the estimated gear ratio can be improved.

  When the engine retard amount is calculated in the routine of the estimated speed ratio calculating method 2 or the estimated speed ratio calculating method 1 in step S109 or S110, the process proceeds to step S111, and the slip is calculated based on the engine retard amount. In order to converge, the engine torque reduction control is performed in cooperation with the increase control of the clamping pressure. Thereafter, this routine is once terminated.

  Next, estimated speed ratio calculation methods 1 and 2 illustrated in the flowchart of FIG. 2 will be described. In the flowchart of the estimated gear ratio calculation method 1 in FIG. 2, it is first determined whether or not the current limit clamping pressure detection flag F1 is “0” (step S201). If the current limit clamping pressure detection flag F1 is “0”, and if the determination in step S201 is affirmative, the process proceeds to step S202, where the estimated speed ratio calculation gradient Δγ′1 and the speed ratio immediately before the limit clamping pressure are determined. γp is calculated. The estimated speed ratio calculation gradient Δγ′1 and the speed ratio γp immediately before the limit clamping pressure can be calculated by the following equations, respectively.

Δγ′1 = {γ (i-α-β) −γ (i-α)} / β
γp = γ (i-1)
Here, α and β are predetermined periods set for each estimated gear ratio calculation method, and specifically, as shown in “in the case of the estimated gear ratio calculation method 1” in the time chart of FIG. In addition, there are a period (α) from the time when the detection determination of the limit clamping pressure is established to a time point that goes back for a predetermined time, and a period (β) from that point to a time point that goes back a predetermined time.

  Subsequently, the estimated speed ratio γ′1 (i) is calculated from the estimated speed ratio calculation gradient Δγ′1 calculated in step S202 and the speed ratio γp immediately before the limit clamping pressure (step S203). This estimated speed change ratio γ′1 can be calculated by the following equation.

γ′1 (i) = γp + Δγ′1 × n
Here, n is a predetermined value, and specifically, as shown in the time chart of FIG. 3, the aforementioned limit is traced back a predetermined time from the time when the limit clamping pressure detection determination is performed. This is the time for setting the gear ratio γp immediately before the clamping pressure.

  On the other hand, if the current limit clamping pressure detection flag F1 is “1” and a negative determination is made in step S201 described above, the process proceeds to step S204, where the estimated speed ratio calculation gradient Δγ′1 and the previous estimation are performed. The estimated speed ratio γ′1 (i) is calculated from the speed ratio γ′1 (i−1).

  When the estimated speed ratio γ′1 (i) is calculated in step S203 or step S204, the process proceeds to step S205, and the engine retard amount is determined by the actual speed ratio γ (i) and the estimated speed ratio γ′1 (i). After that, the process returns to step S111 in the flowchart of FIG. 1 to execute engine torque reduction control.

  2, the third digit “2” of each step number in the flowchart of the above-described estimated transmission ratio calculation method 1 is set to “3”, and the estimated transmission ratio calculation gradient. “Δγ′1” is set to “Δγ′2”, the estimated gear ratio “γ′1” is set to “γ′2”, “α” is set to “A”, and “β” is set to “B” for a predetermined period. The description will be omitted here because it can be explained by replacing it with "."

  As described above, according to the control device of the present invention configured to execute the control shown in FIGS. 1 to 3, when the limit clamping pressure detection control is executed in the continuously variable transmission 1, the continuously variable transmission. The change state of the actual transmission ratio γ and the actual transmission speed Δγ of 1, that is, the occurrence state of slip is identified and determined. Then, an appropriate calculation method corresponding to the state of occurrence of the slip is selected from a plurality of estimated transmission ratio calculation methods with different periods in which data is used retroactively, and the estimated transmission ratio γ ′ is calculated. Is done. As a result, it is possible to accurately estimate the estimated speed ratio used when detecting slip and specifying the slip start time, and it is possible to improve the detection accuracy of the slip start time and the limit clamping pressure.

  Here, the relationship between each of the above specific examples and the present invention will be briefly described. Each of the functional means in steps S106, S107, S109, and S110 described above corresponds to the slip start time determining means in the invention of claim 1. And each functional means of step S104, S105, S108 is equivalent to the driving | running state detection means in this invention of Claim 1. Each functional means of steps S108 to S110 corresponds to the selecting means in the invention of claim 1.

  Note that the present invention is not limited to the above specific example, and can be applied to a control device for a traction type continuously variable transmission in addition to a belt type continuously variable transmission. Further, in the above specific example, as a plurality of types of slip start time determination means in the present invention, the predetermined periods retroactive from the time when the detection determination of the limit clamping pressure is established are the periods α and β and the periods A and B As an example, an estimated transmission ratio calculation method in which the length of a period for collecting data used to calculate the estimated transmission ratio is varied has been described as an example. , A calculation method using multiple types of data with different amounts of data to be used, a calculation method using multiple types of data that has been changed by smoothing or filtering the data used, or A plurality of types of calculation methods with different thresholds used as criteria when determining data can be used. In addition, although two types of estimated gear ratio calculation methods have been described as examples of the plurality of types of slip start time determination means, three or more types of calculation methods may be used. That is, the plurality of types of slip start time determination means in the present invention may be determination means in which the type of data used for the determination, the amount of data to be used, the determination threshold value corresponding to the data, and the like are different from each other.

  Further, in the above specific example, as the plurality of types of slip start time determination means, an example in which the slip start time is determined by a plurality of types of estimated gear ratio calculation methods is shown, but the present invention is not limited to this. In order to accurately determine the start time of the slip reflecting the various driving conditions of the vehicle, a plurality of types of determination means are provided so that an appropriate slip start time determining means can be selected and the slip start time can be determined. I just need it.

  Furthermore, the driving state detected and determined by the driving state detecting means in the present invention is, for example, the behavior of the continuously variable transmission such as a slipping state for a predetermined period retroactive to the past from the slip detection time as in the above specific example. Or a state that can be determined by a physical quantity representing it. In addition, depending on the state that changes according to the accelerator opening and the throttle opening, the state that changes depending on the warm-up state of the engine, continuously variable transmission, or other drive system, the vehicle speed and the road surface condition that is running State that changes according to the engine combustion state (for example, combustion near the stoichiometric or lean region), such as a running state or a driving state In other words.

  Still further, the parameter for selecting the slip start time determination means based on the above operating state by the selection means in the present invention is a counter value such as the limit clamping pressure pre-detection state counter value C1 in the above specific example. In addition to the above, for example, the deviation between the actual transmission ratio and the estimated transmission ratio, the physical quantity calculated based on them, or the actual transmission speed calculated from the actual transmission ratio and the estimated transmission ratio. It may be a deviation from the estimated shift speed, or a physical quantity calculated based on the deviation. In addition, as described above, the selection method for selecting the slip start time determination unit by the selection unit is other than the method of selecting based on the result of comparing and determining the parameter for selection and the threshold value as the determination criterion. For example, a method of selecting based on the result of analyzing the behavior of the actual transmission ratio and the actual transmission speed may be used.

It is a flowchart for demonstrating an example of control by the control apparatus of this invention. It is a flowchart for demonstrating the example of the estimated gear ratio calculation method among the control by the control apparatus of this invention. It is a time chart for demonstrating an 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, 3 ... Lock-up clutch, 5 ... Engine (power source), 13 ... Drive pulley, 14 ... Drive pulley, 15, 16 ... Actuator, 17 ... Belt, 20 ... Drive wheel, 25 ... Transmission Electronic control unit (CVT-ECU).

Claims (1)

The relative slip between the input / output member and the transmission member that transmits power between these input / output members is detected, and a predetermined time point that goes back to the past from the time when the slip is detected is the slip start time. A continuously variable transmission control device for determining
A plurality of types of slip start time determination means for determining a slip start time retroactively from the slip detection time;
Driving state detecting means for detecting a driving state of a vehicle equipped with the continuously variable transmission;
A control device for a continuously variable transmission, comprising: a selection unit that selects the slip start time determination unit based on the detected driving state.

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