JP2014043914A - Lock-up control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lock-up control device for learning and correcting the characteristic dispersion of a solenoid valve for controlling the engagement/disengagement of a lock-up clutch by using a hydraulic sensor to measure a belt clamping pressure.SOLUTION: At a stopping and idling time, the duty ratio to be inputted to a lockup controlling solenoid valve 76 is changed at a constant time gradient, and the duty ratio at the rising time of the oil pressure of a secondary pulley is detected from the detected value of a hydraulic sensor 108 for detecting the oil pressure of a secondary pulley at that time, so that a duty ratio of an instruction to the solenoid valve 76 is corrected by using a difference between the detected value and a standard value.

Description

  The present invention relates to a lockup control device for a vehicle equipped with a belt type continuously variable transmission, and more particularly to a device for suppressing variations in lockup control.

  2. Description of the Related Art Conventionally, there is known a belt type continuously variable transmission that includes a primary pulley and a secondary pulley around which a belt is wound, and has an oil chamber that operates a movable sheave on each pulley. By combining this continuously variable transmission with a torque converter with a lock-up clutch, a configuration suitable for a vehicle transmission can be realized.

  As a hydraulic control device for a torque converter with a lockup clutch, as described in Patent Document 1, a slip control valve is operated by a signal pressure generated by a linear solenoid valve, and an engagement side oil chamber and a release pressure of the lockup clutch An apparatus for slip control by controlling the differential pressure is disclosed.

  In the case of the hydraulic control apparatus having the above-described configuration, there is a problem that the behavior of the lock-up clutch engagement / disengagement differs even when the user performs the same operation due to variations in characteristics of the linear solenoid valve. That is, the linear solenoid valve has a characteristic variation between the command current and the signal pressure due to individual differences, and the characteristic variation also occurs due to secular change of the solenoid valve. For this reason, when such a solenoid valve is used in a hydraulic circuit of a lockup clutch, there is a variation in engagement timing and release timing of the lockup clutch, which causes a problem of shock and uncomfortable feeling.

  In Patent Document 2, in a belt-type continuously variable transmission that controls a shift control valve using a duty solenoid valve and controls a flow rate of hydraulic oil supplied to a primary pulley, variation in shift characteristics is reduced, a shift feeling, A shift control device that can improve fuel consumption has been proposed. This speed change control device includes a speed change control valve, a duty solenoid valve that generates a signal pressure for controlling the speed change control valve, a constant pressure valve that supplies a constant pressure to the duty solenoid valve, and a constant pressure from the constant pressure valve. And a pressure control valve for controlling the pressure of the hydraulic oil supplied to the oil chamber of the secondary pulley, and a hydraulic pressure sensor for detecting the oil pressure of the oil chamber of the secondary pulley. When the vehicle is idling, it outputs a sweep that changes the duty ratio input to the duty solenoid valve at a constant time gradient, detects the duty ratio when the secondary pulley starts to rise from the detected value of the hydraulic sensor, and detects it. The shift instruction duty ratio to the duty solenoid valve is corrected using the difference between the duty ratio and the standard duty ratio.

  If the indicated duty ratio to the duty solenoid valve is changed at a constant time gradient in a stable state, such as when the vehicle is idling, the flow rate of the duty solenoid valve increases as the duty ratio increases. The output pressure of the pressure valve also changes. Since the output pressure of the constant pressure valve is also supplied as a signal pressure to the clamping pressure control valve, when the output pressure of the constant pressure valve changes, the hydraulic pressure of the secondary pulley, which is the output pressure of the clamping pressure control valve, also changes. Since the hydraulic pressure of the secondary pulley rises when the duty ratio indicated to the duty solenoid valve exceeds a certain point, the deviation from the standard characteristic can be detected by detecting the duty ratio at the time of the rise. If this deviation is used to learn and correct the duty ratio indicated to the duty solenoid valve, variations in hydraulic characteristics due to individual differences and changes over time can be suppressed.

  In the above-described learning control, the instruction duty ratio of the solenoid valve for controlling the shift control valve is learned and corrected, but this can also be applied to the hydraulic circuit of the lockup clutch. However, because the solenoid valve has the property that the output hydraulic pressure characteristics are different (has hysteresis) when the duty ratio is increased and when the duty ratio is decreased, the lock-up control has a characteristic different from the shift control. A problem occurs.

  That is, in the case of shift control, since two up-shift side and down-shift side solenoid valves are used and the shift control is performed using the rising characteristics of each solenoid valve, hysteresis hardly poses a problem. Therefore, it is only necessary to detect the rise in hydraulic pressure of the secondary pulley when the duty ratio of the solenoid valve is increased. However, in the case of a lock-up clutch, one solenoid valve is used to control engagement (increase the duty ratio from 0% to 100%) and release control (from 100% to 0%). Therefore, the characteristic at the time of releasing the lockup clutch cannot be understood only by detecting the hydraulic pressure rising of the secondary pulley when the duty ratio of the solenoid valve is increased.

Japanese Patent Laid-Open No. 5-180332 JP 2012-72800 A

  An object of the present invention is to provide a lockup control device capable of learning and correcting characteristic variations and hysteresis of a solenoid valve for lockup control using a hydraulic sensor used in a belt type continuously variable transmission. There is.

  In order to achieve the above object, the present invention provides a belt type continuously variable transmission having a primary pulley and a secondary pulley around which a belt is wound, and an oil chamber for operating a movable sheave on each of the pulleys. A vehicle having a torque converter with a lock-up clutch that transmits engine power to the belt-type continuously variable transmission, and a lock-up control valve that controls hydraulic oil supplied to an oil chamber of the lock-up clutch; A solenoid valve that generates a signal pressure for controlling the lock-up control valve in response to an input control signal, a constant pressure valve that supplies a constant pressure to the solenoid valve, and a constant pressure from the constant pressure valve And a clamping pressure control valve that controls the pressure of hydraulic oil supplied to the oil chamber of the secondary pulley, and oil in the oil chamber of the secondary pulley And an electronic control unit that receives a detection signal from the hydraulic sensor and outputs a control signal to the solenoid valve, and the electronic control unit is input to the solenoid valve when the vehicle is idling. A first sweep output means for increasing the control signal at a constant time gradient; a second sweep output means for decreasing the control signal input to the solenoid valve at a constant time gradient when the vehicle is idling; and the first sweep. A first control signal detecting means for detecting a control signal at the time of rising of the hydraulic pressure of the secondary pulley from a detection value of the hydraulic sensor when the control signal is increased by a constant time gradient by the output means, and the second sweep output means From the detection value of the hydraulic sensor when the control signal is decreased at a constant time gradient, Lock-up to the solenoid valve using a second control signal detecting means for detecting a control signal, and a difference between the control signal detected by the first control signal detecting means and a preset first standard control signal Using the difference between the first correction means for correcting the engagement command control signal, the control signal detected by the second control signal detection means and the preset second standard control signal, the lock to the solenoid valve is performed. There is provided a lockup control device comprising a second correction means for correcting an up release command control signal.

  Due to individual variations of solenoid valves used for lockup control and changes over time, variations in lockup characteristics occur. Therefore, in the present invention, learning correction is performed when the vehicle is idling. This is because when the vehicle is idling, the vehicle speed and the throttle opening are almost zero, and the engine torque and the belt clamping pressure do not change. The correction is preferably performed in a stable state of the vehicle. The stable state of the vehicle refers to a state where the oil temperature, water temperature, voltage, engine speed, etc. are stable. This is because learning in an unstable state promotes variations in lockup characteristics. Furthermore, learning is preferably performed in a non-traveling range such as the P and N ranges. Although learning may be performed in a travel range such as the D range, the signal pressure and line pressure input to the pinching control valve may change, so correction is preferably performed in the non-travel range. In this state, the control signal to the solenoid valve is increased with a constant time gradient. That is, it sweeps out slowly. Since the flow rate of the solenoid valve increases as the control signal changes, the output pressure of the constant pressure valve that supplies the original pressure also changes. Since the output pressure of the constant pressure valve is also supplied as a signal pressure to the clamping pressure control valve, the hydraulic pressure of the secondary pulley, which is the output pressure of the clamping pressure control valve, changes. When the control signal to the solenoid valve exceeds a certain point, the oil pressure of the secondary pulley rises, and the rise can be detected by the oil pressure sensor, so if the control signal value at this rise is detected, the deviation from the standard characteristic is detected it can. In other words, if the difference between the detected control signal and the first standard control signal set in advance is obtained, and the lock-up engagement command control signal to the solenoid valve is learned and corrected using the difference, the individual variation or change over time The variation in the lock-up engagement characteristic due to can be suppressed.

  The solenoid valve has a characteristic that the hydraulic characteristics are different (has hysteresis) when the control signal is increased and when the control signal is decreased. When this is applied to a lockup clutch, the hydraulic characteristics differ between when the lockup clutch is engaged and when it is released. Therefore, in the present invention, at the time of stop idling, not only the rise of the hydraulic pressure of the secondary pulley when the control signal to the solenoid valve is increased with a constant time gradient but also the control signal is decreased from the maximum state with a constant time gradient. The rise of the hydraulic pressure of the secondary pulley at this time is detected by a hydraulic pressure sensor. Then, when the control signal value at the time of rising is detected, the difference from the second standard characteristic is obtained, and the lockup release command control signal to the solenoid valve is learned and corrected using the difference, the variation in the lockup release characteristic is reduced. Can be resolved.

  Solenoid valves include linear solenoid valves and duty solenoid valves. In the former case, the command current and the output hydraulic pressure have a linear relationship, and in the latter case, the command duty ratio and the output hydraulic pressure have a linear relationship. In the case of a solenoid valve, the consumption flow rate changes according to the control signal (command current or command duty ratio). The consumption flow rate is the total flow rate of oil flowing through the solenoid valve. When the control signal is changed from the minimum to the maximum, there is a dead zone until the change in the consumption flow rate of the solenoid valve appears as the hydraulic pressure of the secondary pulley, and this dead zone varies depending on the individual continuously variable transmission. . By learning this dead zone and always aligning it to the standard value, characteristic variations can be suppressed.

  The oil pressure sensor used in the present invention can be shared with the oil pressure sensor used for feedback control of the oil pressure of the secondary pulley, that is, the belt clamping pressure, so that no special oil pressure sensor is required and can be realized at low cost.

  When the control signal is increased or decreased by the first sweep output means or the second sweep output means, it is preferable to have a line pressure increasing means for increasing the line pressure that is the original pressure of the clamping pressure control valve. Since the line pressure is generally low during idling, the change in the secondary pulley hydraulic pressure when the solenoid valve is swept is small, and the hydraulic sensor may be erroneously detected. Therefore, by temporarily increasing the line pressure only at the time of learning, the change in the secondary pulley hydraulic pressure at the time of sweeping becomes large, and erroneous learning can be prevented.

  As described above, when the line pressure is increased during sweeping, it is desirable to increase the engine speed. However, increasing the engine speed deteriorates fuel efficiency. Therefore, by performing learning according to the present invention when the engine is idling up due to another requirement (for example, air conditioner operation or the like), it is possible to prevent deterioration in fuel consumption during learning. It should be noted that the engine load state should be kept constant during learning. In other words, it is desirable to perform control so that there is no disturbance even during idle up (ie, the air conditioner clutch is not turned ON / OFF or the amount of power generation is not changed). If there is a disturbance during learning, erroneous learning can be prevented by discarding the learning result.

  As described above, according to the present invention, the fluctuation and hysteresis of the hydraulic characteristics of the solenoid valve for lockup control are learned and corrected, and the lockup engagement characteristic and the release characteristic are made uniform, so that the shock and the uncomfortable feeling are suppressed or Can be resolved. Further, it is not necessary to add a special sensor or the like, and the existing hydraulic circuit can be used as it is, so that it can be configured simply and inexpensively.

1 is a skeleton diagram showing a configuration of a vehicle equipped with a continuously variable transmission according to the present invention. It is a circuit diagram showing an example of a hydraulic control device of a continuously variable transmission according to the present invention. It is an enlarged view of the principal part of the hydraulic control apparatus shown in FIG. It is a figure which shows the relationship between the duty ratio of a solenoid valve, and consumption flow volume. It is a figure which shows the relationship between the duty ratio of a solenoid valve, and a secondary pulley pressure. It is a figure which shows the relationship between the duty ratio of three types of solenoid valves of a characteristic center, a characteristic upper limit, and a characteristic lower limit, and a consumption flow rate. It is a figure which shows the relationship between the duty ratio of three types of solenoid valves of characteristic center, characteristic upper limit, and characteristic lower limit, and control pressure (output hydraulic pressure). FIG. 3 is a flowchart showing a first embodiment of a learning correction method according to the present invention. It is a flowchart figure which shows 2nd Example of the learning correction method concerning this invention. It is a flowchart figure which shows 3rd Example of the learning correction method concerning this invention.

  FIG. 1 shows an example of the configuration of a vehicle equipped with a belt type continuously variable transmission and a torque converter with a lock-up clutch according to the present invention. An output shaft 1 a of the engine 1 is connected to a continuously variable transmission 2 via a torque converter 3, and the continuously variable transmission 2 is further connected to a drive shaft (output shaft) 32.

  The torque converter 3 is equipped with a lock-up clutch 3a. By engaging the lockup clutch 3a, the pump impeller 3b and the turbine runner 3c are directly connected (locked up). The pump impeller 3b is connected to the engine output shaft 1a, and the turbine runner 3c is connected to the turbine shaft 5. An engagement-side oil chamber 3d is provided on the left side of the lock-up clutch 3a in the drawing, and a release-side oil chamber 3e is provided on the right side, and the differential pressure between these oil chambers 3d, 3e is controlled by the hydraulic control device 7.

  The continuously variable transmission 2 includes a turbine shaft 5 of a torque converter 3 that is an input shaft, and a forward / reverse switching device 8 that transmits the rotation of the turbine shaft 5 to the primary shaft 10 by switching between forward and reverse, a primary pulley 11, A transmission 4 having a secondary pulley 21 and a V-belt 15 wound between both pulleys, and a differential device 30 for transmitting the power of the secondary shaft 20 to a drive shaft 32 are provided.

  The forward / reverse switching device 8 includes a planetary gear mechanism 80, a reverse brake B1, and a direct coupling clutch C1. The reverse brake B1 and the direct coupling clutch C1 are wet multi-plate brakes and clutches, respectively. A sun gear 81 of the planetary gear mechanism 80 is connected to the turbine shaft 5, and a ring gear 82 is connected to the primary shaft 10. The planetary gear mechanism 80 is a single pinion system, the reverse brake B1 is provided between the carrier 84 supporting the pinion gear 83 and the transmission case, and the direct coupling clutch C1 is provided between the carrier 84 and the sun gear 81. When the direct clutch C1 is released and the reverse brake B1 is engaged, the rotation of the turbine shaft 5 is reversed, decelerated and transmitted to the primary shaft 10, and the drive shaft 32 passes through the secondary shaft 20 in the same direction as the engine rotation direction. Since it rotates, it will be in a forward running state. Conversely, when the reverse brake B1 is released and the direct clutch C1 is engaged, the carrier 84 and the sun gear 81 rotate together, so that the turbine shaft 5 and the primary shaft 10 are directly connected, and the drive shaft 32 passes through the secondary shaft 20. Rotates in the direction opposite to the engine rotation direction, so that the vehicle travels backward.

  The primary pulley 11 includes a fixed sheave 11a fixed to the primary shaft 10 and a movable sheave 11b supported on the primary shaft 10 so as to be axially movable and integrally rotatable. A cylinder 12 fixed to the primary shaft 10 is provided behind the movable sheave 11 b, and an oil chamber 13 is formed between the movable sheave 11 b and the cylinder 12. Shift control is performed by controlling the flow rate of the hydraulic oil supplied to the oil chamber 13 with a control valve (not shown).

  The secondary pulley 21 includes a fixed sheave 21a formed on the secondary shaft 20, and a movable sheave 21b supported on the secondary shaft 20 so as to be axially movable and integrally rotatable. A piston 22 fixed to the secondary shaft 20 is provided behind the movable sheave 21 b, and an oil chamber 23 is formed between the movable sheave 21 b and the piston 22. By controlling the hydraulic pressure (secondary pulley pressure) supplied to the oil chamber 23, a belt clamping pressure necessary for torque transmission is applied. In addition, a bias spring 24 for providing an initial clamping pressure is disposed in the oil chamber 23. In the supply oil passage in the vicinity of the oil chamber 23 of the secondary pulley 21, a hydraulic sensor 108 (see FIG. 2) that detects the secondary pulley pressure is provided.

  One end portion of the secondary shaft 20 extends toward the engine side, and the output gear 27 is fixed to this end portion. The output gear 27 meshes with the ring gear 31 of the differential device 30, and power is transmitted from the differential device 30 to the drive shaft 32 extending left and right to drive the wheels.

  The continuously variable transmission 2 is controlled by an electronic control unit 100 (see FIG. 1). The electronic control device 100 includes an engine speed, a vehicle speed (secondary pulley speed), a throttle opening (accelerator opening), a shift position, a primary pulley speed, (vehicle speed), a brake signal, a CVT from the sensors 101 to 103, respectively. The hydraulic oil temperature, secondary pulley pressure, and other signals are input. Of course, other signals may be input as the input signal. The pulley ratio can be detected based on detection signals from the primary pulley rotation speed sensor 105 and the vehicle speed sensor 102.

  The electronic control unit 100 controls a plurality of solenoid valves built in the hydraulic control unit 7 so that the hydraulic pressure of the primary pulley 11, the hydraulic pressure of the secondary pulley 21, the hydraulic pressure of the reverse brake B1 and the direct coupling clutch C1, and further lock-up. The hydraulic pressure of the clutch 3a is controlled. Specifically, the electronic control unit 100 determines the target primary rotational speed according to a shift map set in advance according to the vehicle speed and the throttle opening, and controls the solenoid valve in the hydraulic control unit 7 to thereby The amount of oil supplied to the oil chamber 13 of the primary pulley 11 of the step transmission 2 is controlled, and the primary rotational speed is feedback-controlled to the target value. Further, the belt transmission torque is obtained from the engine torque and the gear ratio, and the supply hydraulic pressure (secondary pulley pressure) to the oil chamber 23 of the secondary pulley 21 is set to the target value so that the minimum belt clamping pressure that does not cause belt slippage is obtained. Feedback control. At this time, the actual secondary pulley pressure is detected by the hydraulic pressure sensor 108.

  FIG. 2 is a hydraulic circuit diagram of an example of the hydraulic control device 7. In FIG. 2, 71 is a primary regulator valve, 72 is a secondary regulator valve, 73 is a clutch modulator valve, 74 is a linear solenoid valve (SLS), 75 is a solenoid modulator valve, 76 is a solenoid valve for lockup control (DSU), 77 Is a lock-up control valve, and 79 is a clamping pressure control valve. In FIG. 2, only the hydraulic circuit related to the secondary pulley 21 and the lockup clutch 3a is shown, but the hydraulic circuit related to the primary pulley 11, the reverse brake B1, and the direct coupling clutch C1 is omitted because it is not directly related to the present invention. To do.

  The primary regulator valve 71 is a valve that regulates the discharge pressure of the oil pump 6 to a predetermined line pressure PL. The primary regulator valve 71 regulates the line pressure PL according to the linear solenoid pressure Psls input to the signal port 71a. The secondary regulator valve 72 regulates the excess oil discharged from the primary regulator valve 71 according to a spring load and a clutch modulator pressure Pcm described later, and outputs a secondary regulator pressure Po that is an original pressure of the lockup control valve 77. doing. The clutch modulator valve 73 is a valve that regulates the line pressure PL to a constant clutch modulator pressure Pcm corresponding to the spring load.

  The linear solenoid valve (SLS) 74 outputs the linear solenoid pressure Psls proportional to the command current value using the clutch modulator pressure Pcm as a source pressure. The linear solenoid pressure Psls is used for line pressure control and pressure control of the oil chamber 23 of the secondary pulley 21. Here, a normally open type linear solenoid valve 74 is used.

  The solenoid modulator valve 75 is a valve that regulates the clutch modulator pressure Pcm and generates a constant solenoid modulator pressure Psm corresponding to the spring load. The solenoid modulator pressure Psm serves as a source pressure for the lock-up control solenoid valve 76 and a shift control solenoid valve (not shown), and is also supplied to the clamping pressure control valve 79 as a signal pressure.

  The lock-up control solenoid valve 76 is a duty solenoid valve that regulates the solenoid modulator pressure Psm and regulates the solenoid pressure Ps according to the duty ratio (control signal) input from the electronic control device 100. Here, a normally closed duty solenoid valve 76 is used. A linear solenoid valve may be used instead of the duty solenoid valve.

  The lockup control valve 77 is a valve that controls the hydraulic pressure of the engagement side oil chamber 3d and the release side oil chamber 3e of the lockup clutch 3a. As shown in FIG. 3, the spool 77a, the spring 77b, the signal port 77c, An input port 77d, a first output port 77e, a second output port 77f, and the like are provided. The spool 77a is biased in one direction by a spring 77b, and a solenoid pressure Ps is input to a signal port 77c formed at a position facing the spring 77b. A secondary regulator pressure Po, which is a source pressure, is supplied to the input port 77d. The first output port 77e is connected to the release side oil chamber 3e of the lockup clutch 3a, and the second output port 77e is connected to the engagement side oil chamber 3d. The output pressure of the first output port 77e is fed back to the feedback port 77g, and the output pressure of the second output port 77f is also fed back to the additional signal port 77h in which the spring 77b is accommodated. A communication port 77i is formed at a position facing the input port 77d, and this communication port 77i is connected to a communication port 77j adjacent to the second output port 77f. 77k is a drain port.

  When the signal pressure Ps input from the solenoid valve 76 to the signal port 77c of the lockup control valve 77 is less than a predetermined value, the spool 77a is pushed by the spring force of the spring 77b and is in the left position in FIG. The pressure Po is supplied to the release side oil chamber 3e via the input port 77d and the first output port 77e, and the lockup clutch 3c is released. On the other hand, when the signal pressure Ps input from the solenoid valve 76 to the signal port 77c of the lock-up control valve 77 becomes equal to or higher than a predetermined value, the spool 77a moves against the spring 77b and reaches the right position in FIG. Therefore, the original pressure Po is supplied to the engagement side oil chamber 3d via the input port 77d, the communication ports 77i, 77j, and the second output port 77f, and the hydraulic pressure in the release side oil chamber 3e is the first output port 77e, drain port. Drain through 77k. As a result, the lock-up clutch 3c enters a lock-up (engaged) state.

  The clamping pressure control valve 79 is a pressure control valve for controlling the hydraulic pressure of the secondary pulley oil chamber 23, and a constant pressure Psm is supplied from the solenoid modulator valve 75 to the signal port 79a on one end side facing the spring load. . A line pressure PL is supplied to the input port 79b, the output port 79c is connected to the secondary pulley oil chamber 23, and the output pressure is fed back to the port 79d. The linear solenoid pressure Psls is supplied to the signal port 79e on the other end side in which the spring is accommodated. Therefore, the hydraulic pressure obtained by amplifying the linear solenoid pressure Psls input to the signal port 79e with a predetermined amplification degree can be supplied to the secondary pulley oil chamber 23. The oil pressure (secondary pulley pressure) in the secondary pulley oil chamber 23 is detected by the oil pressure sensor 108.

  FIG. 4 shows the relationship between the duty ratio and the consumption flow rate in the solenoid valve 76 at the characteristic center (standard product). The consumption flow rate is the total flow rate of oil flowing through the output port and the drain port of the solenoid valve 76. When the duty ratio is increased from 0% with a constant time gradient, the consumption flow rate increases from the point when the duty ratio exceeds D1, as shown by the arrow in FIG. 4, and after the maximum flow rate is reached at the duty ratio D2, the duty ratio is increased. When the ratio is near 100%, the consumed flow rate is stabilized at a predetermined value. The range from 0% to D1 is the dead zone. On the other hand, when the duty ratio is decreased from 100%, the consumption flow rate starts to increase at the duty ratio D3, reaches the maximum flow rate at D4 (D4 <D2), and then decreases to 0 as the duty ratio decreases. As described above, the consumption flow rate characteristic differs (has hysteresis) when the duty ratio increases and decreases.

  FIG. 5 shows changes in the secondary pulley pressure with respect to the duty ratio when the solenoid valve 76 at the characteristic center (standard product) is used. The linear solenoid valve 74 is held in a constant state (for example, an OFF state). When the duty ratio is increased from 0% with a constant time gradient, the consumption flow rate of the solenoid valve 76 is increased from the duty ratio D1, so that the output hydraulic pressure Psm of the solenoid modulator valve 75 is decreased and the signal port 79a of the pinching control valve 79 is decreased. The hydraulic pressure input to the valve also decreases. Therefore, the secondary pulley pressure that is the output pressure of the clamping pressure control valve 79 increases. That is, the secondary pulley pressure rises when the duty ratio to the solenoid valve 76 exceeds a certain point D1. Since the secondary pulley pressure can be detected by the hydraulic pressure sensor 108, the duty ratio D1 at the time of rising can be detected. If the duty ratio is further increased, the secondary pulley pressure decreases to a predetermined value as the duty ratio increases after the secondary pulley pressure reaches the maximum hydraulic pressure at the duty ratio D2.

  On the other hand, when the duty ratio is decreased from 100% with a constant time gradient, the consumption flow rate of the solenoid valve 76 is increased from the duty ratio D3, and the output hydraulic pressure Psm of the solenoid modulator valve 75 is decreased. The secondary pulley pressure, which is the pressure, increases. The oil pressure sensor 108 can detect the duty ratio D3 at the time of rising. When the duty ratio is further decreased, the secondary pulley pressure becomes maximum at the duty ratio D4 and then decreases to a predetermined pressure. As described above, there is a correlation between the consumption flow rate of the solenoid valve and the secondary pulley pressure.

  FIG. 6 shows the relationship between the duty ratio and the consumption flow rate in each solenoid valve at the characteristic center (standard product), the characteristic upper limit, and the characteristic lower limit. In the case of the characteristic upper limit, the characteristic is shifted to the left side (small duty ratio side) compared to the characteristic center, and in the case of the characteristic lower limit, the characteristic is shifted to the right side (large duty ratio side). That is, in the case of the upper limit of the characteristic, the consumption flow rate increases with a smaller duty ratio in the process of increasing the duty ratio, and the consumption flow rate increases with a smaller duty ratio than in the characteristic center in the process of decreasing the duty ratio. . On the other hand, in the case of the characteristic lower limit, in the process of increasing the duty ratio, the consumption flow rate increases at a larger duty ratio than in the center of the characteristic, and in the process of decreasing the duty ratio, the consumption flow rate increases at a higher duty ratio than in the center of the characteristic. . As described above, since the secondary pulley pressure is correlated with the consumption flow rate of the solenoid valve, the secondary pulley pressure also has hysteresis corresponding to the characteristic variation of the solenoid valve.

  FIG. 7 shows the relationship between the duty ratio of the solenoid valve 76 and the output hydraulic pressure. The horizontal axis represents the duty ratio (%), the vertical axis represents the output hydraulic pressure, the solid line represents the characteristic center (standard product), the broken line represents the characteristic upper limit, and the alternate long and short dash line represents the characteristic lower limit. In the case of the characteristic upper limit, the characteristic is shifted to the left side (small duty ratio side) compared to the characteristic center, and in the case of the characteristic lower limit, the characteristic is shifted to the right side (large duty ratio side). Taking the case of the characteristic center as an example, when the duty ratio is increased from 0%, as shown by the arrow, the output hydraulic pressure increases from the predetermined duty ratio D1, and the output hydraulic pressure increases almost in proportion to the duty ratio. Then, the maximum hydraulic pressure is reached at a duty ratio Da in the vicinity of a duty ratio of 100%. On the other hand, when the duty ratio is decreased from 100%, the output hydraulic pressure starts to drop from the duty ratio D3 lower than Da as indicated by the arrow, and the output hydraulic pressure becomes almost zero at the duty ratio Db lower than the duty ratio D1.

  As described above, the hydraulic characteristics of the solenoid valve 76 also have hysteresis and have characteristic variations due to individual differences among the solenoid valves. Since the output hydraulic pressure of the solenoid valve 76 is input as the signal pressure of the lockup control valve 77, individual differences and hysteresis of the solenoid valve 76 affect the engagement / release characteristics of the lockup clutch. In particular, due to the hysteresis of the solenoid valve 76, the engagement / release characteristics of the lockup clutch differ between when the duty ratio is increased (when lockup is engaged) and when it is decreased (when lockup is released). . The hydraulic pressure rise duty ratio D1 when the duty ratio increases corresponds to the duty ratio D1 when the secondary pulley pressure rises as shown in FIG. 5, and the hydraulic pressure fall duty ratio D3 when the duty ratio decreases decreases as shown in FIG. This corresponds to the duty ratio D3 when the pulley pressure rises. By detecting these duty ratios D1 and D3, individual differences and hysteresis of the solenoid valve 76 can be known.

Next, the learning correction method for the lockup clutch according to the present invention will be described.
(1) When the duty ratio of the solenoid valve 76 is changed from 0% to 100% in the stop idling state, the consumption flow rate changes as shown in FIG. Since the solenoid valve 76 uses the solenoid modulator pressure Psm, a decrease in the solenoid modulator pressure Psm corresponding to the drive amount occurs. The solenoid modulator pressure Psm is used not only for the solenoid valve 76 but also for the signal pressure of the clamping pressure control valve 79, but is only supplied to each closed signal port. Therefore, the solenoid modulator pressure Psm does not decrease.

(2) Since the solenoid modulator pressure Psm is input as a signal pressure to the port 79a of the clamping pressure control valve 79, the decrease in the solenoid modulator pressure Psm shifts the pressure regulation position of the clamping pressure control valve 79, as shown in FIG. The change of the secondary pulley pressure is brought about. Changes in the secondary pulley pressure can be detected by the hydraulic sensor 108. However, if the duty ratio of the solenoid valve 76 changes abruptly, the solenoid modulator pressure Psm also changes abruptly and the clamping pressure control valve 79 hunts, so the duty ratio of the solenoid valve 76 changes slowly with a constant time gradient ( Sweep)

(3) If the duty ratio when the hydraulic pressure sensor 108 starts to change the hydraulic pressure is detected, the duty ratios D1 and D3 at the time of rising in FIG. 5 can be obtained. Specifically, the duty ratio D1 at the rise of the secondary pulley pressure when the duty ratio is increased from 0% with a constant time gradient is detected, the duty ratio D1 is compared with the standard duty ratio, and the differential duty By using the ratio as the correction duty ratio and correcting the entire duty ratio output, variations in lockup engagement characteristics can be suppressed. On the other hand, the duty ratio D3 at the rise of the secondary pulley pressure when the duty ratio is decreased from 100% with a constant time gradient is detected, the duty ratio D3 is compared with the standard standard duty ratio, and the differential duty ratio is calculated. If the correction duty ratio is corrected for the entire duty ratio output, variations in the lockup release characteristics can be suppressed.

[First embodiment]
Next, a specific learning correction method will be described with reference to FIG.
(1) First, it is determined whether or not the vehicle is idling (step S1). Specifically, it is determined whether the vehicle is in a neutral state such as the P and N ranges and the vehicle is in a stable idling state. The stable state of the vehicle is a state in which the oil temperature, water temperature, voltage, and the like are stable. When idling is stopped, the vehicle speed and the throttle opening are equal to or less than predetermined values near 0, and the engine speed is idle speed. A state that is stable in the vicinity. In this state, the continuously variable transmission is in the closed state at the lowest level, the linear solenoid pressure Psls is maintained at a constant pressure, and the line pressure PL is also maintained at a constant pressure.

(2) Next, the indicated duty ratio to the solenoid valve 76 is increased from 0% to 100% with a constant time gradient (step S2). That is, in order to detect the rising duty ratio D1 of the secondary pulley pressure, the sweep output is performed slowly. As a result, the valve opening degree of the solenoid valve 76 changes, and an increase in the consumption flow rate of the solenoid valve causes a decrease in the solenoid modulator pressure Psm.

(3) Next, since the secondary pulley pressure also rises due to the decrease in the solenoid modulator pressure Psm, the hydraulic pressure fluctuation is detected by the hydraulic pressure sensor 108. Thereby, the duty ratio D1 at the time of hydraulic pressure rise is detected (step S3). In addition, when the duty ratio to the solenoid valve 76 is increased, the hydraulic pressure of the engagement side oil chamber 3d of the lockup clutch 3a is increased and locked up, but the learning of the present invention is similar to the P and N ranges. Since it is performed temporarily in the neutral state, there is no fear of the vehicle jumping out.

(4) Next, a differential duty ratio ΔD1 between the detected duty ratio D1 and the standard value is obtained, and this differential value is stored in the memory (step S4).

(5) Next, the indicated duty ratio to the solenoid valve 76 is lowered from 100% to 0% with a constant time gradient (step S5), and the hydraulic pressure fluctuation of the secondary pulley pressure at that time is detected by the hydraulic sensor 108, and the hydraulic pressure A duty ratio D3 at the time of rising is detected (step S6). Then, a difference duty ratio ΔD3 between the detected duty ratio D3 and the standard value is obtained, and this difference value is stored in the memory (step S7).

(6) Finally, the lockup engagement instruction value and the release instruction value are corrected (updated) using the stored difference values ΔD1 and ΔD3 (step S8). By using this corrected engagement instruction value or release instruction value to control the lockup control solenoid valve 76, variations in the engagement characteristics and release characteristics of the lockup clutch 3a can be eliminated. For example, when the value of the detected duty ratio D1 is 5% larger than the standard value (difference value = + 5%), it means that the characteristic is shifted to the lower limit side by 5%. As a result, the value obtained by adding 5% can be output, so that the engagement characteristic can be adapted to the standard value.

(7) If only the individual variation of the solenoid valve 76 is eliminated, the above-described learning correction may be performed once. However, by periodically performing the above-described learning correction and updating the correction value, It is also possible to suppress variations in lockup characteristics that accompany changes.

[Second Embodiment]
When learning the lock-up clutch of the present invention, an operation for increasing the line pressure may be performed. As described above, when the duty ratio of the solenoid valve 76 is swept, the linear solenoid pressure Psls is kept constant, but usually the linear solenoid pressure Psls is set to the minimum pressure and the line pressure PL is also kept to the minimum pressure. . However, if the line pressure PL, which is the original pressure of the clamping pressure control valve 79, is low, the change in the secondary pulley pressure, which is the output pressure of the clamping pressure control valve 79, is reduced during sweeping, and the hydraulic sensor 108 detects the rise of the secondary pulley pressure. There are concerns about false detection.

  Therefore, when the solenoid valve 76 is swept, the line pressure PL is increased by a predetermined value (the linear solenoid pressure Psls is increased by a predetermined value), and the change in the secondary pulley pressure during the sweep is increased, so that the hydraulic sensor 108 It becomes possible to prevent erroneous detection and, consequently, erroneous learning.

  FIG. 9 shows an example of a learning correction method in the second embodiment. First, as in FIG. 8, it is determined whether or not the vehicle is idling (step S1). If the vehicle is idling, the line pressure PL is increased by a predetermined value and held (step S10). Specifically, the line current PL is increased by a predetermined pressure by increasing the command current of the linear solenoid valve 74 by a predetermined value and increasing the linear solenoid pressure Psls by a predetermined value. The operation after step S2 in FIG. 8 is performed in a state where the line pressure PL is increased. The operations after step S2 are the same as in FIG.

[Third embodiment]
The learning of the lock-up clutch of the present invention is preferably performed while the idle-up control is being performed. Idle-up is an operation that automatically increases the idling speed when the engine load increases due to air conditioner operation during idling. In order to increase the line pressure as in the second embodiment, since it is necessary to increase the engine speed, there is a concern that the fuel consumption will deteriorate. However, during idle-up, the engine speed increases due to another requirement. Therefore, by performing the learning of the present invention during the idle-up, it is possible to prevent deterioration in fuel consumption for performing the learning.

  FIG. 10 shows an example of a learning correction method in the third embodiment. First, as in FIG. 8, it is determined whether or not the vehicle is idling (step S1). If the vehicle is idling, it is next determined whether or not idle up is being performed (step S11). If the idle-up is not being performed, the learning correction is stopped. If the idle-up is being performed, the operations after step S2 in FIG. 8 are performed.

  The present invention is not limited to the above embodiment. In the above embodiment, the duty solenoid valve is used as the solenoid valve for lock-up control, but a linear solenoid valve may be used. In this case, a current value may be used as the control signal instead of the duty ratio.

DESCRIPTION OF SYMBOLS 1 Engine 2 Continuously variable transmission 3 Torque converter 3a Lock-up clutch 3d Engagement side oil chamber 3e Release side oil chamber 7 Hydraulic controller 11 Primary pulley 13 Primary oil chamber 21 Secondary pulley 23 Secondary oil chamber 71 Primary regulator valve 72 Secondary regulator Valve 73 Clutch modulator valve 74 Linear solenoid valve 75 Solenoid modulator valve (constant pressure valve)
76 Solenoid valve for lockup control 77 Lockup control valve 79 Nipping pressure control valve 100 Electronic control unit 108 Hydraulic sensor

Claims (3)

A belt-type continuously variable transmission having a primary pulley and a secondary pulley around which a belt is wound, each of which is provided with an oil chamber for operating a movable sheave, and the engine power for the belt-type continuously variable transmission A torque converter with a lock-up clutch that transmits to the vehicle,
A lock-up control valve that controls hydraulic oil supplied to the oil chamber of the lock-up clutch;
A solenoid valve that generates a signal pressure for controlling the lock-up control valve in accordance with an input control signal;
A constant pressure valve for supplying a constant pressure to the solenoid valve;
A constant pressure control valve that controls the hydraulic oil supplied to the oil chamber of the secondary pulley by supplying a constant pressure as a signal pressure from the constant pressure valve;
A hydraulic sensor for detecting the hydraulic pressure of the oil chamber of the secondary pulley;
An electronic control device that receives a detection signal from the hydraulic sensor and outputs a control signal to the solenoid valve;
The electronic control device
A first sweep output means for increasing a control signal input to the solenoid valve at a constant time gradient when the vehicle is idling;
A second sweep output means for reducing a control signal input to the solenoid valve at a constant time gradient when the vehicle is idling;
First control signal detection means for detecting a control signal at the time of rising of the hydraulic pressure of the secondary pulley from a detection value of the hydraulic sensor when the control signal is increased at a constant time gradient by the first sweep output means;
Second control signal detection means for detecting a control signal at the time of hydraulic pressure rise of the secondary pulley from a detection value of the hydraulic pressure sensor when the control signal is decreased by a constant time gradient by the second sweep output means;
First correction means for correcting a lockup engagement command control signal to the solenoid valve using a difference between the control signal detected by the first control signal detection means and a first standard control signal set in advance; ,
Second correction means for correcting a lockup release command control signal to the solenoid valve using a difference between the control signal detected by the second control signal detection means and a preset second standard control signal; A lockup control device comprising:   The apparatus further comprises line pressure increasing means for increasing a line pressure, which is an original pressure of the pinching control valve, when the control signal is increased or decreased by the first sweep output means or the second sweep output means. Item 2. The lockup control device according to Item 1.   The vehicle performs engine idle-up control when a predetermined idle-up condition is satisfied, and is controlled by the first sweep output means or the second sweep output means when the idle-up control is being performed. The lockup control device according to claim 2, wherein the lockup engagement command control signal or the lockup release command control signal to the solenoid valve is corrected by increasing or decreasing the signal.

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