JP2004332878A - Control device of continuously variable transmission - Google Patents

Control device of continuously variable transmission Download PDF

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Publication number
JP2004332878A
JP2004332878A JP2003132222A JP2003132222A JP2004332878A JP 2004332878 A JP2004332878 A JP 2004332878A JP 2003132222 A JP2003132222 A JP 2003132222A JP 2003132222 A JP2003132222 A JP 2003132222A JP 2004332878 A JP2004332878 A JP 2004332878A
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Japan
Prior art keywords
change rate
speed ratio
continuously variable
variable transmission
ratio change
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Pending
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JP2003132222A
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Japanese (ja)
Inventor
Kazumi Hoshiya
Kunihiro Iwatsuki
Yasunori Nakawaki
康則 中脇
邦裕 岩月
一美 星屋
Original Assignee
Toyota Motor Corp
トヨタ自動車株式会社
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Priority to JP2003132222A priority Critical patent/JP2004332878A/en
Publication of JP2004332878A publication Critical patent/JP2004332878A/en
Pending legal-status Critical Current

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of enhancing the detection accuracy of a slip of a continuously variable transmission using the theoretical rate of change of the gear ratio. <P>SOLUTION: In the control device of a continuously variable transmission, a belt stretched over a drive pulley and a driven pulley is held by applying the thrust in the axial direction of the pulleys, and a slip to either pulley of the belt is detected based on the theoretical rate of change of the gear ratio and the actual rate of change of the gear ratio obtained from the input rotational speed and the output rotational speed. The control device has a means for calculating the theoretical rate of change of the gear ratio (Steps S1-S15) to calculate the theoretical rate of change of the gear ratio based on a calculation model in which the theoretical rate of change of the gear ratio is proportional to the change in the thrust. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a continuously variable transmission capable of continuously changing a gear ratio, and more particularly to a device for detecting slippage of a continuously variable transmission.
[0002]
[Prior art]
Belt-type continuously variable transmissions and traction-type continuously variable transmissions transmit torque using a frictional force between a belt and a pulley and a shearing force of traction oil between a disk and a roller. Therefore, when a torque exceeding the torque capacity acts, slippage occurs between the belt and the pulley or between the disk and the roller. If slippage occurs in the continuously variable transmission, it is necessary to perform an operation to eliminate the slippage, and to reduce the clamping force for setting the torque capacity as much as possible with respect to the input torque. When detecting the so-called limit clamping pressure at which slippage occurs, slippage may occur.
[0003]
As described above, slip detection in the continuously variable transmission must be always detected in controlling the continuously variable transmission. Since the slip in the continuously variable transmission appears as a change in the rotational speed of any member, the slip can be detected by a change in the gear ratio or the shift speed. That is, a value that is a so-called reference representing a state in which no slip occurs is determined, and the slip of the continuously variable transmission can be detected by comparing the value that is constantly detected with the so-called reference value.
[0004]
Conventionally, a theoretical gear ratio change rate is set as a so-called reference value, and the actual gear ratio change rate obtained based on the input rotational speed and the output rotational speed is compared with the theoretical gear ratio change rate. Patent Document 1 describes that slip is detected based on the result. The device described in Patent Document 1 is configured to learn the line pressure based on the detection of slip. Further, conventionally, a device that determines a slip limit by a change in a belt pressing force in a belt-type continuously variable transmission and adjusts the pressing force so as not to exceed a detected slip limit in order to prevent a slip from occurring. Is described in Patent Document 2.
[0005]
[Patent Document 1]
JP-A-6-11022 (paragraphs (0126) to (0131))
[Patent Document 2]
JP 2001-12593 A (Abstract, Claims 1, 2, Paragraph (0013), FIG. 4)
[0006]
[Problems to be solved by the invention]
In the invention described in Patent Document 1, the change ratio of the speed ratio per unit time is determined by utilizing the fact that the speed ratio is controlled by the flow ratio control valve flow rate and the circumference of the belt is constant. I'm asking. More specifically, the gear ratio is differentiated by the volume of the hydraulic actuator on the drive pulley side (that is, the ratio between the minute change amount of the gear ratio and the minute change amount of the volume is obtained). The theoretical flow ratio change rate per unit time is calculated by multiplying the flow rate. Therefore, the theoretical gear ratio change rate during the predetermined time is calculated by integrating the value per unit time.
[0007]
Therefore, conventionally, as described in Patent Literature 1, the calculation for obtaining the theoretical speed ratio change rate is complicated, which may cause a delay or an error in the slip detection control. In addition, since the integration operation is performed in order to obtain the theoretical gear ratio change rate, if the calculation is continued or repeated, errors inevitably intervening in the integration operation accumulate, and the slip detection accuracy is reduced. May decrease. Furthermore, since the theoretical speed ratio change rate is calculated using the flow rate at the speed ratio control valve, an error in the flow rate at the speed ratio control valve affects the calculation accuracy of the theoretical speed ratio change rate and, consequently, the slip detection accuracy. , The detection accuracy may be reduced.
[0008]
The present invention has been made in view of the above technical problem, and has as its object to provide a control device that can easily and accurately detect slippage by using a theoretical gear ratio change rate. It is.
[0009]
Means for Solving the Problems and Their Functions
In order to achieve the above object, the invention of claim 1 provides a method in which a belt wound around a driving pulley and a driven pulley is pinched by applying an axial thrust to each pulley, In a control device for a continuously variable transmission that detects slippage based on a theoretical gear ratio change rate and an actual gear ratio change rate obtained from an input rotational speed and an output rotational speed, the theoretical gear ratio change rate is determined by the change amount of the thrust. A control device comprising a theoretical speed ratio change rate calculating means for calculating the theoretical speed ratio change rate based on a proportional calculation model.
[0010]
Therefore, in the first aspect of the present invention, the theoretical speed ratio change rate is determined based on a calculation model in which the theoretical speed ratio change rate is proportional to the change in the thrust in one of the pulleys that sets the speed ratio. Then, the actual speed ratio change rate obtained from the input rotation speed and the output rotation speed is compared with the above-described theoretical speed ratio change rate, and slippage in the continuously variable transmission is detected. Therefore, the calculation of the theoretical gear ratio change rate becomes easy, and slippage in the continuously variable transmission is quickly and accurately detected.
[0011]
According to a second aspect of the present invention, there is provided a control device for a continuously variable transmission which detects slip based on a comparison result between a theoretical speed ratio change rate and an actual speed ratio change rate obtained from an input rotation speed and an output rotation speed. Learning means for learning the operating characteristics of the speed ratio control valve for controlling the ratio, and a criterion for judging slippage based on a comparison result between the theoretical speed ratio change rate and the actual speed ratio change rate. And a slip determination criterion setting unit that changes before and after the control.
[0012]
Therefore, according to the second aspect of the present invention, the operating characteristics of the speed ratio control valve are learned, and before and after the learning, the slip determination criterion is changed. Therefore, the operating characteristics of the speed ratio control valve are reflected in the determination of slippage by comparing the theoretical speed ratio change rate and the actual speed ratio change rate. That is, while the theoretical gear ratio change rate, which is affected by the operating characteristics of the gear ratio control valve, is used for determining slip, the operating characteristics of the gear ratio control valve are reflected in the slip determination criterion. The accuracy of slip determination or detection is improved.
[0013]
Further, according to the third aspect of the invention, slip is detected by comparing the theoretical speed ratio change rate of the continuously variable transmission whose torque capacity changes due to the pinching force with the actual speed ratio change rate obtained from the input rotation speed and the output rotation speed. In the control device for a continuously variable transmission, learning means for learning the operating characteristics of the speed ratio control valve for controlling the speed ratio, and after the learning by the learning means is completed, the clamping pressure is reduced, and the clamping pressure is reduced. And a slip detecting means for detecting slip caused by the decrease.
[0014]
Therefore, according to the third aspect of the invention, after the operating characteristics of the speed ratio control valve are learned, that is, after the operating characteristics of the speed ratio control valve can be taken in as control data, the squeezing pressure is reduced and the squeezing pressure is reduced. Is executed to detect slippage due to the decrease in the vehicle speed. Therefore, by reflecting the operating characteristics of the speed ratio control valve, it is possible to perform control in a state in which an error caused by the operating characteristics of the speed ratio control valve is eliminated, and as a result, slippage in the continuously variable transmission is reduced. Detection is performed quickly and accurately.
[0015]
According to a fourth aspect of the present invention, there is provided a stepless continuously detecting slip based on a comparison result between a theoretical speed ratio change rate obtained by an operation including an integration operation and an actual speed ratio change rate obtained from an input rotation speed and an output rotation speed. The transmission control device includes an initialization unit that updates an initial value of the calculation of the theoretical gear ratio change rate in a predetermined state where the torque acting on the continuously variable transmission is stable. A control device characterized in that:
[0016]
Therefore, according to the fourth aspect of the present invention, the initial value for calculating the theoretical gear ratio change rate is updated in a predetermined state in which the torque is stable. Factors are suppressed, and as a result, slip detection accuracy using the theoretical speed ratio change rate is improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described based on specific examples. First, an example of a drive system including a continuously variable transmission according to the present invention will be described. FIG. 5 schematically illustrates a drive mechanism including a belt-type continuously variable transmission 1 and the continuously variable transmission. Reference numeral 1 is connected to a power source 5 via a forward / backward switching mechanism 2 and a fluid transmission mechanism 4 having a lock-up clutch 3.
[0018]
The power source 5 includes an internal combustion engine, an internal combustion engine and an electric motor, or an electric motor. In the following description, the power source 5 is referred to as an engine 5. The fluid transmission mechanism 4 has, for example, a configuration similar to that of a conventional torque converter, and includes a pump impeller rotated by an engine 5, a turbine runner disposed opposite to the pump impeller, and a stator disposed therebetween. It is configured to supply a spiral flow of fluid generated by a pump impeller to the turbine runner to rotate the turbine runner and transmit torque.
[0019]
In the transmission of torque through such a fluid, inevitable slippage occurs between the pump impeller and the turbine runner, which causes a reduction in power transmission efficiency. And a lock-up clutch 3 for directly connecting to an output-side member such as The lock-up clutch 3 is configured to be controlled by hydraulic pressure, is controlled to a fully engaged state, a completely released state, and a slip state that is an intermediate state between these states, and can appropriately control the slip rotation speed. It has become.
[0020]
The forward / reverse switching mechanism 2 is a mechanism that is employed in accordance with the fact that the rotation direction of the engine 5 is limited to one direction, and outputs the input torque as it is, and outputs it in reverse. 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, the ring gear 7 is arranged concentrically with the sun gear 6, and between the sun gear 6 and the ring gear 7, a pinion gear 8 meshed with the sun gear 6 and another pinion gear 9 meshed with the pinion gear 8 and the ring gear 7 are arranged. The pinion gears 8 and 9 are held by the carrier 10 so as to rotate and revolve. Further, a forward clutch 11 for integrally connecting the two rotating elements (specifically, the sun gear 6 and the carrier 10) is provided, and by selectively fixing the ring gear 7, the direction of the output torque is provided. Is provided.
[0021]
The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and each of a drive pulley 13 and a driven pulley 14 arranged in parallel with each other includes a fixed sheave and a hydraulic pulley. And a movable sheave that is moved back and forth in the axial direction by actuators 15 and 16. Therefore, the groove width of each of the pulleys 13 and 14 changes by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 17 wound around each of the pulleys 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 the carrier 10 which is an output element of the forward / reverse switching mechanism 2.
[0022]
A hydraulic pressure (line pressure or its correction pressure) corresponding to the torque input to the continuously variable transmission 1 is supplied to the hydraulic actuator 16 of the driven pulley 14 via a hydraulic pump and a hydraulic control device (not shown). I have. Therefore, when each sheave of the driven pulley 14 sandwiches the belt 17, tension is applied to the belt 17, and a clamping pressure (contact pressure) between each pulley 13, 14 and the belt 17 is secured. .
[0023]
On the other hand, the hydraulic actuator 15 of the drive pulley 13 is connected to a speed ratio control valve for upshift and a speed ratio control valve for downshift (each not shown). Then, by performing duty control on one of the speed ratio control valves by feedback control that matches the input speed to the target speed, pressure oil is supplied to and discharged from the hydraulic actuator 15, and a groove width (corresponding to a predetermined speed ratio) is formed. (Effective diameter or winding diameter). The force pressing the movable sheave in each of the pulleys 13 and 14 in the axial direction is the thrust. Therefore, the thrust is the elasticity of the pressure oil and centrifugal force supplied to the hydraulic actuators 15 and 16 and the return spring and the like. Produced by force.
[0024]
The driven pulley 14 is connected to a differential 19 via a gear pair 18, and outputs torque from the differential 19 to driving wheels 20. Therefore, in the above drive mechanism, the lock-up clutch 3 and the continuously variable transmission 1 are arranged in series between the engine 5 and the drive wheels 20.
[0025]
Various sensors are provided to detect the operation state (running state) of the vehicle equipped with the above-described continuously variable transmission 1 and the engine 5. That is, a turbine speed sensor 21 that detects an input speed (speed of the turbine runner) to the continuously variable transmission 1 and outputs a signal, and an input speed that detects a 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 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 particularly shown, an accelerator opening sensor that detects the amount of depression of the accelerator pedal and outputs a signal, a throttle opening sensor that detects the opening of the throttle valve and outputs a signal, and a brake pedal are depressed. A brake sensor or the like that outputs a signal in the case is provided.
[0026]
In order to control the engagement / disengagement of the forward clutch 11 and the reverse brake 12, control the squeezing force of the belt 17, control the gear ratio, and control the lock-up clutch 3, the transmission Electronic control unit (CVT-ECU) 25 is provided. The electronic control unit 25 is configured mainly by a microcomputer as an example, performs calculations in accordance with a predetermined program based on input data and data stored in advance, and various states such as forward, reverse or neutral, It is configured to execute setting of a required clamping force, setting of a gear ratio, engagement / disengagement of the lock-up clutch 3, and control of a slip rotation speed and the like.
[0027]
Here, as an example of data (signal) input to the transmission electronic control unit 25, a signal of an input rotation speed (input rotation speed) Nin of the continuously variable transmission 1 and an output of the continuously variable transmission 1 will be described. The signal of the rotation speed (output rotation speed) No is input from the corresponding sensor. An engine electronic control unit (E / G-ECU) 26 for controlling the engine 5 outputs a signal of an engine speed Ne, a signal of an engine (E / G) load, and a depression amount of an accelerator pedal (not shown). Is input.
[0028]
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 same can be improved. For example, a target driving force is determined based on a required driving amount and a vehicle speed represented by an accelerator opening, and a target output required to obtain the target driving force is determined based on the target driving force and the vehicle speed. The engine speed for obtaining the target output at the optimum fuel efficiency is obtained based on a prepared map, and the gear ratio is controlled so as to become the engine speed.
[0029]
In the above-described continuously variable transmission 1, a clamping force is set according to an input torque, a running state of a vehicle, and the like in order to maintain a power transmission efficiency as good as possible. However, since the torque exceeding the torque capacity due to the actually set clamping force may act on the continuously variable transmission 1 and cause slippage in the continuously variable transmission 1, the control device according to the present invention employs the following: The slip is detected as described in (1).
[0030]
FIG. 1 is a flowchart for explaining an example of the control. First, the thrust WOUT of the output driven pulley 14 is calculated (step S1). In particular,
WOUT = (Pd + Psch) * Aout
Is calculated by the following equation. That is, the hydraulic actuator 16 is added to the pressure obtained by adding the hydraulic pressure Pd acting on the hydraulic actuator 16 on the driven pulley 14 side and the sum Psch of the centrifugal hydraulic pressure generated by the hydraulic actuator 16 and the elastic force generated by a return spring or the like. Is multiplied by the pressure receiving area Aout to calculate the output-side thrust WOUT. Since this thrust is based on the hydraulic pressure actually acting, it can be said to be an actual thrust.
[0031]
On the other hand, the thrust (hereinafter, tentatively required thrust) WOUTSLP at the driven pulley 14 corresponding to the input torque is calculated (step S2). That is, it is a thrust that generates the minimum clamping force that can transmit the input torque without causing slip, and is a thrust corresponding to the state where the safety factor SF is “1”. This is for example
WOUTSLP = Tt * cosα / (2 * μ * Rin)
Is calculated. Here, Tt is an input torque, α is a skew angle of the belt 17 between the pulleys 13 and 14, μ is a coefficient of friction between the pulleys 13 and 14, and the belt 17, and Rin is a winding radius of the belt 17 around the driving pulley 13. is there.
[0032]
The input torque Tt is determined based on the engine speed Ne and the engine load (eg, throttle opening) (step S2A), and is determined based on the estimated torque Te and the inertia torque (step S2B). be able to.
[0033]
The actual thrust WOUT is generally higher than the required thrust WOUTSLP in a state where the continuously variable transmission 1 is operated without slipping, and the excess (or a margin) is used as the safety factor SF. Equivalent. Therefore, the safety factor SF is calculated (step S3). Specifically, the safety factor SF is calculated as a ratio (WOUT / WOUTSLP) between the actual thrust WOUT and the required thrust WOUTSLP.
[0034]
The thrust ratio τ is obtained from the safety factor SF thus obtained and the gear ratio γ at that time (step S4). Specifically, the thrust ratio τ is obtained from a previously prepared map based on the safety factor SF and the gear ratio γ.
[0035]
On the other hand, the position (position in the axial direction) WDx of the movable sheave on the drive pulley 13 is determined (step S5). Since the speed ratio γ is equal to the ratio of the winding radius of the belt 17 to each of the pulleys 13 and 14, in step S5, the position WDx of the movable sheave is obtained based on a map based on the speed ratio γ.
[0036]
The routine shown in the flowchart of FIG. 1 is repeatedly executed at predetermined intervals, and therefore, the position WDx of the movable sheave is also determined at predetermined intervals. Therefore, in step S6, the position change amount dx for each routine is obtained. This can be obtained as the difference between the position WDx (i) of the movable sheave obtained this time and the previous value WDx (i-1).
[0037]
The belt 17 in the specific example described here has a structure in which a large number of blocks made of thin metal pieces are arranged in close contact with each other in an annular shape, and the blocks are bound by metal hoops (each not shown). It is. Each of the pulleys 13 and 14 transmits torque by sandwiching the block and pressing and moving the block in the circumferential direction. The number dN of the blocks wound around the driving pulley 13 is calculated (step S7). This is determined based on a map based on the speed ratio γ and the input rotation speed of the continuously variable transmission 1, that is, the rotation speed NIN of the drive pulley 13.
[0038]
Next, the axial movement amount dx / dN of the movable sheave per block is calculated (step S8). In the speed change in the continuously variable transmission 1, the pressure oil is supplied to or discharged from the hydraulic actuator 15 on the driving pulley 13 side, and accordingly, the belt 17 is pulled or loosened. This is caused by an increase or decrease in the interval (ie, groove width) between the fixed sheave and the movable sheave in 14. Since such a change is caused by a change in the thrust in one of the pulleys 13 and 14, the amount of change in thrust VKVALLDX at the drive pulley 13 is obtained based on the amount of axial movement dx / dN obtained at step S8. (Step S9). Specifically, the thrust change amount VKVALDX is obtained based on a map based on the axial movement amount dx / dN of the movable sheave per block. The map is set separately for upshifts and downshifts.
[0039]
The pressure Pin of the hydraulic actuator 15 on the driving pulley 13 side is calculated using the thrust change amount VKVALDX (step S10). this is,
Pin = (VKVALDX + WOUT / τ-mechanical thrust) / Ain
Can be calculated by the following equation. Here, the mechanical thrust is a total sum of a thrust based on centrifugal hydraulic pressure and a thrust corresponding to a mechanical element such as a return spring, and Ain is a pressure receiving area of the hydraulic actuator 15 on the drive pulley 13 side. By transforming this equation,
Pin * Ain + Mechanical thrust-WOUT / τ = VKVALDX
It becomes. The first and second terms on the left side of this equation are the thrust WIN generated by the hydraulic actuator 15 on the driving pulley 13 side.
WIN−WOUT / τ = VKVALDX
Can be transformed into
[0040]
It is assumed that this is proportional to the above-described axial movement amount dx / dN of the movable sheave per block.
dx / dN = K * (WIN−WOUT / τ)
Holds. This relationship is schematically shown in FIG. 2 by a diagram. The proportionality constant K is determined depending on the operating state of the continuously variable transmission 1. Therefore, the operating state can be predetermined as a map using the operating state as a parameter. In the case of a steady running state in which no shift occurs, the proportionality constant K is “0”. The map is set separately for upshifts and downshifts.
[0041]
On the other hand, the line pressure PL, which is the original pressure of the pressure oil supplied to the hydraulic actuator 15 on the driving pulley 13 side, is calculated (step S11). Since the hydraulic pressure Pd in the hydraulic actuator 16 on the driven pulley 14 side for setting the squeezing pressure is set using the line pressure PL 1 as the original pressure, it can be used.
PL = Pd * A + B (A and B are constants)
Can be calculated as
[0042]
The transmission ratio control valve flow rate q is calculated using the line pressure PL thus calculated (step S12). That is, when the speed ratio control valve (not shown) is constituted by a duty solenoid valve, the flow rate is determined based on the difference between the pressure on the input side and the pressure on the output side and the duty ratio. The pressure on the input side becomes the line pressure in the case of an upshift for supplying the pressure oil, and the pressure on the output side becomes the hydraulic pressure Pin in the hydraulic actuator 15 on the drive pulley 13 side. Therefore, in the case of an upshift, the flow rate q can be obtained based on the map from the differential pressure (PL-Pin) and the shift command duty ratio DDS1. On the other hand, in the case of a downshift in which the pressure oil is discharged, the pressure on the input side becomes the pressure Pin of the hydraulic actuator 15 and the pressure on the output side becomes the atmospheric pressure, that is, “0”. 0) and the downshift command duty ratio DDS2, the flow rate q can be obtained based on the map.
[0043]
Since the gear ratio γ is subjected to feedback control (step S12A) using the difference between the input rotational speed NIN and its target rotational speed NINT as a feedback deviation, the duty ratios DDS1 and DDS2 for the gear change are read (step S12B). ), This may be used in step S12.
[0044]
Since the gear ratio control valve flow rate q is essentially the amount of pressure oil supplied to and discharged from the hydraulic actuator 15 on the drive pulley 13 side, this is used as the cross-sectional area of the piston in the hydraulic actuator 15 (the pressure receiving area Ain). By this, the amount of movement dx1 of the movable sheave in the driving pulley 13 in the axial direction is obtained (step S13). When the movable sheave of the drive pulley 13 moves in the axial direction, the groove width of the drive pulley 13, that is, the winding radius of the belt 17 changes, thereby causing a speed change. Therefore, the axial movement amount dx1 of the movable sheave and the speed ratio The theoretical speed ratio γ1 is determined based on γ (step S14). For example, the theoretical gear ratio γ1 (i + 1) at the next time point (one routine ahead) is obtained from a map of the current theoretical gear ratio γ1 (i) and the axial movement amount dx1 of the movable sheave.
[0045]
The amount of change in the theoretical speed ratio γ1 thus calculated per unit time is the theoretical speed ratio change rate Δγ1. For example, the change amount (γ1 (i) −γ1 (i−1)) of the theoretical speed ratio γ1 during the time Δt of one routine of the flowchart shown in FIG. 1 is divided by the time Δt ({γ1 (i)). −γ1 (i−1)} / Δt).
[0046]
Similarly, the actual speed ratio change rate Δγ (i) is calculated (step S16). The actual speed ratio γ (i) is a value calculated as a ratio between the input rotation speed NIN and the output rotation speed NOUT of the continuously variable transmission 1. Therefore, the actual speed ratio change rate Δγ (i) is calculated by the unit time The amount of change per hit. Ie
Δγ (i) = {γ (i) −γ (i−1)} / Δt
Can be calculated as
[0047]
Therefore, the theoretical speed ratio change rate Δγ1 is theoretically calculated based on the amount q of the pressure oil supplied / discharged to / from the hydraulic actuator 15 on the driving pulley 13 side. This is a value that does not include the slip between the two. On the other hand, the actual transmission ratio change rate Δγ is calculated based on the actual rotation speed of each of the pulleys 13 and 14, and therefore, when the continuously variable transmission 1 slips, This includes the change in the gear ratio resulting from the change.
[0048]
Therefore, the slip of the continuously variable transmission 1 is detected by comparing the theoretical speed ratio change rate Δγ1 with the actual speed ratio change rate Δγ (step S17). Specifically, the absolute value of the difference between the actual speed ratio change rate Δγ and the theoretical speed ratio change rate Δγ1 is calculated, and it is determined whether the absolute value is equal to or greater than a predetermined threshold value Δγh.
[0049]
If a negative determination is made in step S17, it means that the actual speed ratio change rate Δγ is close to the theoretical speed ratio change rate Δγ1, and no slippage has occurred in the continuously variable transmission 1. Conversely, if the determination in step S17 is affirmative, the actual speed ratio change rate Δγ deviates greatly from the theoretical speed ratio change rate Δγ1, which indicates that the belt speed of the continuously variable transmission 1 is low. Since it is clear that this is caused by the slip of No. 17, the determination of the belt slip is established, and a corresponding process for suppressing or converging the slip is executed (step S18). The corresponding processing is, for example, control for increasing the clamping pressure or control for decreasing the engine torque.
[0050]
Therefore, in the device of the present invention configured to execute the control shown in FIG. 1 described above, utilizing the relationship in which the thrust change amount at the drive pulley 13 for setting the shift and the theoretical speed ratio change rate Δγ1 are proportional. The theoretical speed ratio change rate Δγ1 is calculated. In other words, the theoretical gear ratio change rate Δγ1 is calculated based on a calculation model in which the thrust change amount is proportional to the theoretical gear ratio change rate Δγ1, so that the calculation can be performed easily, quickly, and accurately. Therefore, according to the control device of the present invention, when slip is detected based on the comparison result between the theoretical speed ratio change rate Δγ1 and the actual speed ratio change rate Δγ, the detection control can be performed easily, quickly, and accurately. Can be.
[0051]
The control device according to the present invention calculates the theoretical speed ratio change rate Δγ1 using the flow rate q of the speed ratio control valve, and the speed ratio control valve flow rate q is based on a duty command value for the speed ratio control valve. I'm asking. Although the relationship between the flow rate control valve flow rate q and the duty ratio is constant for each speed ratio control valve, there is variation among the speed ratio control valves due to individual differences. Therefore, an error may occur between the flow rate calculated in step S12 in FIG. 1 described above and the actual flow rate. The flow rate obtained by the former calculation is used to calculate the theoretical speed ratio change rate Δγ1, and the actual flow rate of the latter is reflected in the actual speed ratio change rate Δγ. Therefore, an error between the calculated value of the speed ratio control valve flow rate and the actual value appears as a difference between the theoretical speed ratio change rate Δγ1 and the actual speed ratio change rate Δγ or a difference between the theoretical speed ratio γ1 and the actual speed ratio γ.
[0052]
If the threshold value Δγh for the slip determination described above is the same for all the speed ratio control valves or the continuously variable transmission 1, slip is determined including the above-described error. The accuracy of slip determination may be reduced. Therefore, the control device of the present invention is configured to perform control in consideration of the characteristics of the speed ratio control valve in order to improve the accuracy of slip determination. One example is shown in a flowchart in FIG.
[0053]
In FIG. 3, first, it is determined whether learning correction of a command value according to valve characteristics has been completed (step S21). The valve characteristics are characteristics of a speed ratio control valve (not shown) for supplying and discharging pressure oil to and from the hydraulic actuator 15 on the drive pulley 13 side shown in FIG. 4 shows a relationship between a duty command value and a flow rate for a downshift gear ratio control valve. The learning correction of the command value is to correct the duty command value by learning so that the flow rate obtained at a predetermined duty command value for the speed ratio control valve matches the flow rate actually generated at the speed ratio control valve. It is.
[0054]
As described above, the flow rate obtained by calculation from the duty command value appears as the theoretical gear ratio γ1, and the actual flow rate appears as the actual gear ratio γ. By comparing these gear ratios γ1, γ, the gear ratio is calculated. An error between the theoretical value and the actual value of the flow rate at the control valve can be obtained. The duty command value is changed so that the error becomes zero, or a correction coefficient for the duty command value is obtained by actually setting a predetermined gear ratio, thereby obtaining a command value for the gear ratio control valve. Can learn.
[0055]
In the above step S21, it is determined whether or not such learning correction has been completed. If the determination is affirmative, the threshold value Δγh for slip determination (that is, the slip determination criterion) is used. Is adopted (step S22). Conversely, if the determination in step S21 is negative, a value corresponding to the state before the learning correction of the command value of the speed ratio control valve is completed is set (step S23).
[0056]
The threshold value Δγh set in accordance with the presence or absence of the learning correction for the command value of the speed ratio control valve may be a predetermined constant value or may be a variable corresponding to the correction amount. The threshold value Δγh used before the learning correction for the command value of the gear ratio control valve is completed is set to a value larger than the threshold value Δγh used after the learning correction is completed. The slip determination in a state where the learning correction for the command value of the speed ratio control valve has not been completed may include a relatively large error, and conversely, the learning correction is terminated. In this case, the possibility of making an erroneous determination is small even if the threshold value Δγh is reduced, and accurate determination can be made.
[0057]
After setting the threshold value for slip determination in this way, the theoretical gear ratio change rate Δγ1 is calculated (step S24), the actual gear ratio change rate Δγ is calculated (step S25), and these change rates Δγ1 are further calculated. , Δγ are determined to be greater than or equal to a threshold value Δγh (step S26). If a negative determination is made in step S26, the routine of FIG. 3 is terminated once without performing any particular control. Conversely, if a positive determination is made in step S26, the slippage is stopped. Is established, and a predetermined corresponding process is executed (step S27). Each control from step S24 to step S27 is as shown from step S1 to step S18 shown in FIG.
[0058]
Accordingly, when the control shown in FIG. 3 is configured to execute, the individual difference in the characteristics of the speed ratio control valve or the individual difference of the continuously variable transmission 1 can be reflected in the slip determination, and thus the slip determination is performed. Can be performed easily and quickly, and the determination accuracy can be improved.
[0059]
As described with reference to FIG. 1, the axial movement amount of the movable sheave per block constituting the belt 17 is obtained, and the theoretical gear ratio γ1 and The rate of change Δγ1 is calculated, and the slip is determined. The routine shown in the flowchart of FIG. 1 is repeatedly executed at predetermined short intervals. Therefore, the theoretical gear ratio change rate Δγ1 and the actual gear ratio change rate Δγ actually used for slip determination are integrated (integrated) values each time the routine of FIG. 1 is repeated. That is, the calculation for obtaining the theoretical speed ratio change rate Δγ1 includes an integration operation. Therefore, if each integration process includes a slight error, the error is also integrated, which affects the accuracy of the slip determination. The control device of the present invention performs the following control in order to minimize the influence of such an integration operation.
[0060]
FIG. 4 is a flowchart showing an example of the control. First, the theoretical speed ratio change rate Δγ1 is calculated (step S31). The calculation method or procedure is as described with reference to FIG. Next, it is determined whether learning correction of the command value according to the valve characteristics has been completed (step S32). This is the same determination as in step S21 shown in FIG. If an affirmative determination is made in step S32, a value corresponding to the completion of the learning correction has been set as the threshold Δγh for slip determination (step S33). This is the same control as in step S22 shown in FIG.
[0061]
It is determined whether the condition for detecting the necessary clamping pressure is satisfied (step S34). Here, the required squeezing pressure is a squeezing pressure obtained by adding a pressure that allows for a predetermined safety such as a portion corresponding to a road surface input to a limit squeezing pressure for setting a so-called torque capacity that is balanced with the input torque from the engine 5 side. In order to detect the required pinching pressure, conditions such as a stable torque such as an input torque acting on the continuously variable transmission 1 and a normal execution of the control are required. It is determined whether or not is established. Specifically, the running state of the vehicle equipped with the continuously variable transmission 1 is in a steady state or a quasi-steady state, and the necessary clamping pressure for the input torque at that time has not been set or corrected. This is a necessary clamping pressure detection condition, and it is determined in step S34 whether or not this condition is satisfied.
[0062]
If the determination in step S34 is affirmative, it is determined whether or not the detection operation has been started, that is, whether or not the detection operation has already been started (step S35). If the determination in step S35 is affirmative, the initial value of the calculation of the theoretical speed ratio change rate Δγ1 is updated (step S36). That is, when the vehicle is in a stable running state such as a steady running state or a quasi-steady running state, the torque acting on the continuously variable transmission 1 is stable, and the theoretical speed ratio γ1 and the rate of change Δγ1 are calculated. Since the factors causing disturbance are reduced, the value in that state (for example, the gear ratio determined from the input / output rotation speed) is adopted as the initial value to reduce the error.
[0063]
Thereafter, the operation of detecting the required clamping pressure is executed (step S37). Specifically, the clamping pressure is gradually reduced so as not to overshoot. In the process, the theoretical speed ratio γ1 and its change rate Δγ1 are sequentially calculated. At the same time, the actual speed ratio change rate Δγ is calculated (step S38). If the detection operation has already been started and a negative determination is made in step S35, the process immediately proceeds to step S37 to continue the detection control of the necessary clamping pressure.
[0064]
On the other hand, if a negative determination is made in step S34 because the detection condition of the necessary clamping pressure is not satisfied, the clamping pressure is changed to the pressure or the line pressure (or its correction pressure) corresponding to the input torque at that time. After executing the corresponding process I such as setting (step S39), the process proceeds to step S38. If a negative determination is made in step S32 because the learning correction of the command value in accordance with the valve characteristics has not been completed, the value before correction is set as the threshold value Δγh (step S40), and thereafter The process proceeds to step S38. The control in step S40 is similar to the control in step S23 shown in FIG.
[0065]
Since the theoretical speed ratio change rate Δγ1 is calculated in step S31 and the actual speed ratio change rate Δγ is calculated in step S38, it is determined whether or not the absolute value of these differences is equal to or larger than the threshold value Δγh ( Step S41). If a negative determination is made in step S41, since no slippage has occurred, the routine returns without performing any particular control. Conversely, if the determination is affirmative in step S41, the corresponding processing II similar to step S18 in FIG. 1 or step S27 in FIG. 3 described above, such as the establishment of a slip determination, is executed (step S42). ).
[0066]
Therefore, according to the control device according to the present invention configured to execute the control shown in FIG. 4, before the start of the detection control of the necessary clamping pressure, the steady state or the quasi-stationary state in which the start condition of the detection control is satisfied Then, the initial value of the calculation of the theoretical speed ratio change rate Δγ1 including the integration operation is updated, so that the error with respect to the theoretical speed ratio change rate Δγ1 can be suppressed. Accordingly, it is possible to accurately detect the required clamping pressure and the limit clamping pressure.
[0067]
Here, the relationship between each of the above specific examples and the present invention will be briefly described. The functional means of the above-described steps S1 to S15 correspond to the theoretical gear ratio change rate calculating means of the present invention, The functional means of S32 corresponds to the learning means of the present invention, and the functional means of steps S22, S23, S33, and S40 correspond to the slip determination criterion setting means of the present invention. Further, the functional means of steps S34 to S438 and S41 correspond to the slip detecting means of the present invention, and the functional means of step S36 corresponds to the initializing means of the present invention.
[0068]
It should be noted that the present invention is not limited to the specific example described above, and the procedure or arithmetic expression for calculating the theoretical speed change ratio can be appropriately adopted other than that described in the above specific example. What is necessary is just to be based on the calculation model proportional to the amount of change. The speed ratio control valve may be a linear solenoid valve that operates in proportion to current or voltage, other than the so-called duty control valve.
[0069]
【The invention's effect】
As described above, according to the first aspect of the invention, the theoretical gear ratio change rate is calculated based on the calculation model in which the theoretical gear ratio change rate is proportional to the change in thrust in one of the pulleys for setting the gear ratio. The slip ratio of the continuously variable transmission is detected by comparing the theoretical speed ratio change rate and the actual speed ratio change rate obtained from the input rotation speed and the output rotation speed. The ratio can be easily calculated, and slippage in the continuously variable transmission can be quickly and accurately detected.
[0070]
According to the second aspect of the present invention, the operating characteristics of the speed ratio control valve are learned, and before and after the learning, the slip determination criterion is changed. The change rate and the actual gear ratio change rate can be reflected in the determination of slip, and as a result, the theoretical gear ratio change rate, which is affected by the operation characteristics of the gear ratio control valve, is used for slip determination. On the other hand, since the operating characteristics of the speed ratio control valve are reflected in the slip determination criteria, the accuracy of slip determination or detection can be improved.
[0071]
Further, according to the invention of claim 3, after the operating characteristics of the speed ratio control valve are learned, that is, after the operating characteristics of the speed ratio control valve can be taken in as control data, the clamping pressure is reduced and In order to execute control to detect slippage due to a decrease in clamping pressure, by reflecting the operation characteristics of the speed ratio control valve, control in a state in which an error caused by the operation characteristics of the speed ratio control valve is eliminated is performed. As a result, it is possible to quickly and accurately detect slippage in the continuously variable transmission.
[0072]
According to the fourth aspect of the present invention, the initial value for calculating the rate of change of the theoretical gear ratio is updated in a predetermined state where the torque is stable. Error factors such as the above can be suppressed, and the accuracy of slip detection using the theoretical gear ratio change rate can be improved.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating an example of control by a control device according to the present invention.
FIG. 2 is a diagram schematically illustrating a proportional relationship between a thrust change amount and an axial movement amount of a movable sheave.
FIG. 3 is a flowchart for explaining another control example by the control device of the present invention.
FIG. 4 is a flowchart for explaining still another control example by the control device of the present invention.
FIG. 5 is a diagram schematically illustrating an example of a drive mechanism including a continuously variable transmission targeted by the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 5 ... Engine (power source), 13 ... Driving pulley, 14 ... Driven pulley, 17 ... Belt, 25 ... Electronic control unit for transmission (CVT-ECU), 26 ... Electronic control unit for engine (E / G-ECU).

Claims (4)

  1. A belt wound around a driving pulley and a driven pulley is pinched by applying an axial thrust to each pulley, and the slip of any of the belts on one of the pulleys is calculated based on a theoretical speed ratio change rate, an input rotation speed, and an output rotation speed. In the control device of the continuously variable transmission that detects based on the actual speed ratio change rate obtained from
    Control of a continuously variable transmission, comprising: theoretical speed ratio change rate calculating means for calculating the theoretical speed ratio change rate based on a calculation model in which the theoretical speed ratio change rate is proportional to the thrust change amount. apparatus.
  2. In the control device of the continuously variable transmission that detects slip based on a comparison result between the theoretical speed ratio change rate and the actual speed ratio change rate obtained from the input rotation speed and the output rotation speed,
    Learning means for learning operating characteristics of a speed ratio control valve for controlling a speed ratio;
    And a slip criterion setting means for changing a criterion for judging slippage based on a comparison result between the theoretical gear ratio change rate and the actual gear ratio change rate before and after learning by the learning means. Control device for a continuously variable transmission.
  3. A control device for a continuously variable transmission that detects slippage by comparing the theoretical gear ratio change rate of a continuously variable transmission whose torque capacity changes due to pinching pressure with the actual gear ratio change rate obtained from an input rotation speed and an output rotation speed. ,
    Learning means for learning operating characteristics of a speed ratio control valve for controlling a speed ratio;
    A control device for a continuously variable transmission, comprising: a slip detecting means for reducing the clamping force after the learning by the learning means is completed and detecting a slip caused by the decrease in the clamping force.
  4. A control device for a continuously variable transmission that detects slip based on a comparison result between a theoretical speed ratio change rate obtained by an operation including an integration operation and an actual speed ratio change rate obtained from an input rotation speed and an output rotation speed,
    And a step of updating the initial value of the calculation of the rate of change of the theoretical transmission ratio in a predetermined state in which the torque acting on the continuously variable transmission is stable. Transmission control device.
JP2003132222A 2003-05-09 2003-05-09 Control device of continuously variable transmission Pending JP2004332878A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010180995A (en) * 2009-02-07 2010-08-19 Nissan Motor Co Ltd Belt slip state determination device of v-belt type continuously variable transmission
KR20110021684A (en) * 2009-08-26 2011-03-04 쟈트코 가부시키가이샤 Continuously variable transmission and control method for the same
KR20180066756A (en) * 2016-12-09 2018-06-19 현대오트론 주식회사 Kick down Gear ratio studying device and method of Continuously Variable Transmission vehicle

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010180995A (en) * 2009-02-07 2010-08-19 Nissan Motor Co Ltd Belt slip state determination device of v-belt type continuously variable transmission
KR20110021684A (en) * 2009-08-26 2011-03-04 쟈트코 가부시키가이샤 Continuously variable transmission and control method for the same
JP2011047459A (en) * 2009-08-26 2011-03-10 Jatco Ltd Continuously variable transmission and method for controlling the same
US8414453B2 (en) 2009-08-26 2013-04-09 Jatco Ltd Continuously variable transmission and control method thereof
KR101691664B1 (en) 2009-08-26 2016-12-30 쟈트코 가부시키가이샤 Continuously variable transmission and control method for the same
KR20180066756A (en) * 2016-12-09 2018-06-19 현대오트론 주식회사 Kick down Gear ratio studying device and method of Continuously Variable Transmission vehicle
KR101917376B1 (en) 2016-12-09 2018-11-09 현대오트론 주식회사 Kick down Gear ratio studying device and method of Continuously Variable Transmission vehicle

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