JP2008069878A - Shift control device for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the worsening of startability due to erroneous determination by determining the start after towing with high accuracy. <P>SOLUTION: A transmission controller 12 sets the target position of a step motor 27 to be located corresponding to a speed ratio closer to a Hi-side a transmission oil temperature TMP is lower. It feeds the step motor 27 to the target position after starting an engine. It feeds the step motor 27 to be located corresponding to the speed ratio from the target position further closer to the Hi-side when primary pressure Ppri does not reach predetermined pressure before a predetermined waiting time passes after feeding the step motor 27 to the target position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a shift control device for a belt-type continuously variable transmission, and more particularly to a technique for preventing belt slippage when an engine is started after being towed.

  The belt type continuously variable transmission changes the primary pulley's groove width by changing the primary pressure supplied to the primary pulley by the speed change control valve, and changes the diameter ratio between the primary pulley and the secondary pulley, thereby reducing the gear ratio. Change to stage. The speed change control valve is connected to the center of the speed change link, and the movable flange of the primary pulley and the step motor are connected to both ends of the speed change link, thereby constituting a mechanical feedback mechanism of the speed change ratio.

  In addition, a return spring is arranged on the primary pulley side so that the gear ratio at the time of towing is higher than the lowest Lo to prevent the pulley from being damaged due to non-lubricating high rotation during towing.

  However, in the continuously variable transmission configured as described above, when starting the engine after being towed, the pulley is not in the lowest position, while the step motor is in the lowest position by the initialization operation. This is the position where the drain port and primary port communicate. For this reason, the primary pressure is not supplied until the vehicle travels and the step motor is sent to the Hi side, and belt slip due to insufficient primary pressure may occur.

Therefore, in Patent Document 1, when the primary pressure does not reach the predetermined pressure within a predetermined time after the engine is started, it is determined that the engine is started after being towed, and the process proceeds to the Hi side until the primary pressure reaches the predetermined pressure. It is moved. As a result, even if the primary pulley is located on the Hi side with respect to the maximum Lo position due to being towed, etc., the primary pressure is not supplied until the vehicle starts and the step motor is sent to the Hi side. Slip is suppressed.
JP 2004-125037 A

  However, although the method disclosed in Patent Document 1 can suppress belt slip, the determination accuracy of whether or not the engine is started after being towed at a low temperature is not sufficient. If the stepping motor is sent to the Hi side because it is erroneously determined that the engine has started after being pulled, even though it is not after being towed, the gear ratio is changed to the Hi side and the startability is deteriorated. This is because, when the outside air temperature is low, the viscosity of the hydraulic fluid of the transmission is high, so that the increase in the primary pressure is delayed. It is because it will judge.

  Further, in the above method, when it is determined that the engine is started after being towed, the target position of the step motor is set to the Hi side with respect to the current position and the step motor is sent to the Hi side, and the primary pressure rises to a predetermined value. The step motor is stopped when the pressure is reached. However, since the drive speed is fast, the step motor is eventually sent to the target position, which causes the startability to deteriorate. Even if it is going to return the step motor sent to the target position to the Lo side, it interferes with another control that regulates the upper limit of the change speed, and cannot be returned quickly.

  The present invention has been made in view of such a conventional technical problem, and it is an object of the present invention to determine engine start after towing with high accuracy and prevent deterioration of startability due to erroneous determination. Furthermore, when it is determined that the engine is started after being towed and the speed change actuator is moved to the Hi side, it is an object to minimize the amount of movement and suppress the deterioration of startability.

  The present invention relates to a position corresponding to a target gear ratio by connecting a shift control valve for controlling a primary pressure supplied to the primary pulley to the center of the shift link, and connecting a movable flange of the primary pulley to one end of the shift link. By connecting a speed change actuator that moves to the other end of the speed change link, a mechanical feedback mechanism that controls the speed change ratio to the target speed change ratio and the movable flange is urged toward the opposite fixed flange, and the towed object And an urging means for setting the current gear ratio to the Hi side from the maximum Lo, and a position corresponding to the gear ratio on the Hi side as the oil temperature of the transmission decreases. Means for setting the shift actuator to a target position; means for moving the shift actuator to the target position after engine startup; and the shift actuator When the primary pressure does not reach the predetermined pressure before the predetermined waiting time elapses after moving the motor to the target position, the position corresponding to the Hi-side gear ratio from the target position is further increased. And a means for moving toward

  According to the present invention, when the engine of the vehicle is started (when the key is turned on), the shift actuator is fed to the Hi side by a predetermined amount according to the oil temperature of the transmission so that the shift actuator is on the Hi side when performing the pulling determination. As a result, the primary pressure easily rises even at low temperatures, and it is possible to prevent erroneous determination that the primary pressure rise delay at low temperatures is due to traction.

  If post-traction control is performed due to an erroneous determination, the speed change actuator moves to the Hi side and the startability deteriorates. According to the present invention, it is possible to avoid the adverse effects caused by the erroneous determination.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the small gear ratio side or the high speed side is expressed as “Hi side”, and the large gear ratio side or the low speed side is expressed as “Lo side”.

  FIG. 1 shows a schematic configuration of a belt type continuously variable transmission 1 provided with a shift control device according to the present invention.

  The belt-type continuously variable transmission 1 includes a primary pulley 2 and a secondary pulley 3 that are arranged so that their V-grooves are aligned, and a belt 4 is stretched between the pulleys 2 and 3. The engine 5 is disposed coaxially with the primary pulley 2, and a lockup torque converter 6 and a forward / reverse switching mechanism 7 are sequentially provided between the engine 5 and the primary pulley 2 from the engine 5 side.

  The forward / reverse switching mechanism 7 includes a double pinion planetary gear set 7 a as a main component, a sun gear is coupled to the engine 5 via the torque converter 6, and a carrier is coupled to the primary pulley 2. The forward / reverse switching mechanism 7 further includes a forward clutch 7b that directly connects the sun gear and the carrier of the double pinion planetary gear set 7a, and a reverse brake 7c that fixes the ring gear. , And the rotation input from the engine 5 via the torque converter 6 is reversely decelerated and transmitted to the primary pulley 2 when the reverse brake 7c is engaged.

  The rotation to the primary pulley 2 is transmitted to the secondary pulley 3 via the belt 4. The rotation of the secondary pulley 3 is then transmitted to drive wheels (not shown) via the output shaft 8, the gear set 9, and the differential gear device 10. In order to make it possible to change the rotational transmission ratio (transmission ratio) between the primary pulley 2 and the secondary pulley 3 during the power transmission described above, one of the flanges forming the grooves of the primary pulley 2 and the secondary pulley 3 is fixed. The flanges 2a and 3a are used, and the other flanges 2b and 3b are movable flanges that can be displaced in the axial direction. These movable flanges 2b and 3b are respectively urged toward the fixed flanges 2a and 3a by supplying the primary pressure Ppri and the secondary pressure Psec created using the line pressure as the original pressure to the primary pulley chamber 2c and the secondary pulley chamber 3c. Thus, the belt 4 is frictionally engaged with the pulley flange to enable the power transmission between the primary pulley 2 and the secondary pulley 3.

  Further, the return spring 2d (biasing means) is arranged in the primary pulley chamber 2c, and the return spring 3d is arranged in the secondary pulley chamber 3c, so that the movable flanges 2b and 3b face the fixed flanges 2a and 3a facing each other. The return spring 2d is energized to prevent fluctuations in the groove width due to fluctuations in hydraulic pressure, slipping out, etc., and to maintain the gear ratio at the time of towing at a speed ratio on the Hi side from the maximum Lo. It is set to be larger than the urging force of the spring 3d.

  At the time of shifting, the groove width of the pulleys 2 and 3 is changed by the differential pressure between the primary pressure Ppri and the secondary pressure Psec generated corresponding to the target gear ratio, as will be described later, and the belt 4 is wound around the pulleys 2 and 3. The target gear ratio is realized by continuously changing the diameter.

  The primary pressure Ppri and the secondary pressure Psec are controlled by the shift control hydraulic circuit 11 together with the hydraulic pressure supplied to the forward clutch 7b that is engaged when the forward travel range is selected and the reverse brake 7c that is engaged when the reverse travel range is selected.

  The transmission controller 12 detects a signal from the primary pulley rotation speed sensor 13 that detects the primary pulley rotation speed Npri, a signal from the secondary pulley rotation speed sensor 14 that detects the secondary pulley rotation speed Nsec, and the primary pressure Ppri. A signal from the primary pressure sensor 15 that performs detection, a signal from the secondary pressure sensor 16 that detects the secondary pressure Psec, a signal from the accelerator pedal position sensor 17 that detects the accelerator pedal position APP, and a selection range signal from the inhibitor switch 18 And a signal from the oil temperature sensor 19 that detects the transmission oil temperature TMP, and a signal (engine speed and fuel injection time) related to the transmission input torque from the engine controller 20 that controls the engine 5 are input. .

  As shown in FIG. 2, the transmission control hydraulic circuit 11 includes an oil pump 21 that is driven by the engine 5. The hydraulic oil pressure-fed from the oil pump 21 to the oil passage 22 is adjusted to the line pressure PL by the pressure regulator valve 23. The line pressure PL of the oil passage 22 is adjusted to the secondary pressure Psec by the pressure reducing valve 24 on the one hand and supplied to the secondary pulley chamber 3c, and is adjusted to the primary pressure Ppri by the speed change control valve 25 on the other hand to the primary pulley chamber 2c. To be supplied. The pressure regulator valve 23 controls the line pressure PL by the driving duty to the solenoid 23a, and the pressure reducing valve 24 controls the secondary pressure Psec by the driving duty to the solenoid 24a.

  The speed change control valve 25 has a neutral position 25 a, a pressure increase position 25 b, and a pressure reduction position 25 c, and is connected to the center of the speed change link 26. A step motor 27 as a speed change actuator is connected to one end of the speed change link 26, and the movable flange 2 b of the primary pulley 2 is connected to the other end. When the step motor 27 is sent to a position corresponding to the target gear ratio, the speed change link 26 swings around the connecting portion with the movable flange 2b as a fulcrum, and the speed change control valve 25 is changed from the neutral position 25a to the pressure increasing position 25b or the pressure reducing position. Displace to position 25c.

  As a result, when the target speed ratio is higher than the current speed ratio, the line pressure port communicates with the primary pressure port, and when the target speed ratio is Lo, the primary pressure port communicates with the drain port. As a result, the primary pressure Ppri is increased with the line pressure PL as the original pressure, or is reduced by the drain, and the differential pressure with respect to the secondary pressure Psec is changed, whereby the shift to the Hi side or the shift to the Lo side is performed. .

  The progress of the speed change is fed back to the speed change link 26 via the movable flange 2b of the primary pulley 2, and the speed change link 26 swings with a connecting portion with the step motor 27 as a fulcrum, and the speed change control valve 25 is moved to the pressure increasing position. 25b or the pressure reducing position 25c is displaced toward the neutral position 25a. Thus, when the target speed ratio is achieved, the speed change control valve 25 is returned to the neutral position 25a, and the target speed ratio is maintained.

  Commands according to the solenoid drive duty of the pressure regulator valve 23, the solenoid drive duty of the pressure reducing valve 24, and the target gear ratio to the step motor 27 are controlled along with the control of the hydraulic pressure supplied to the forward clutch 7b and the reverse brake 7c shown in FIG. It is determined by the transmission controller 12.

  As shown in FIG. 2, the transmission controller 12 includes a pressure control unit 12a and a transmission control unit 12b.

  The pressure control unit 12 a determines the solenoid driving duty of the pressure regulator valve 23 and the solenoid driving duty of the pressure reducing valve 24.

  The shift control unit 12b obtains a target input rotation speed by referring to a predetermined shift map based on the secondary pulley rotation speed Nsec and the accelerator pedal position APP, and divides this by the secondary pulley rotation speed Nsec, thereby changing the gear ratio. The final transmission ratio that is the final target value is obtained. Then, a target transmission ratio for making the transmission ratio close to the ultimate transmission ratio with a desired response is calculated, and the position (number of steps) of the step motor 27 for realizing the target transmission ratio is obtained. To

  After engine 5 is started (after key-on), transmission controller 12 initializes step motor 27 (initialization operation). In general, in this initialization operation, the step motor 27 is sent to the lowest position, but in this embodiment, in addition to this, in order to prevent belt slip at the time of engine start after being towed, the control described below is performed. Do.

  FIG. 3 is a flowchart showing the contents of control performed by the transmission controller 12 when the engine is started.

  According to this, first, in step S11, it is determined whether the engine rotation speed is equal to or higher than a predetermined value (for example, 450 rpm or higher). If it is equal to or higher than the predetermined value, it is determined that the engine 5 is started, and the process proceeds to step S12. Otherwise, the process is terminated.

  In step S12, the transmission oil temperature TMP detected by the oil temperature sensor 19 is read.

  In step S13, the target position (first target position) of the step motor 27 in the precharge operation performed after the initialization operation of the step motor 27 is set. The first target position is set according to the transmission oil temperature TMP, and the position corresponding to the Hi-side gear ratio is set as the transmission oil temperature TMP is lower. The first target position is set, for example, in two stages according to the transmission oil temperature TMP. When the transmission oil temperature TMP is at an extremely low temperature (−20 ° C. or lower), the first target position corresponds to the transmission ratio on the Hi side. The position to perform is set.

  In step S14, the step motor 27 is sent to the first target position, and a precharge operation for increasing the primary pressure Ppri is started.

  In step S15, a timer value T is set. This timer value T measures the elapsed time from the start of the precharge operation. The timer value T is set with reference to the table shown in FIG. The timer value T is set to a large value when the transmission oil temperature TMP is in a low temperature range, and is gradually set to a small value as the transmission oil temperature TMP becomes high, and is constant after the transmission oil temperature TMP reaches a predetermined temperature. Value is set.

  In step S16, it is determined whether the primary pressure Ppri has reached a predetermined pressure. The predetermined pressure is set to 0.3 MPa, for example. If the primary pressure Ppri has not reached the predetermined pressure, the process proceeds to step S17. On the other hand, if the primary pressure Ppri has reached the predetermined pressure, it is determined that there is no shift control valve 25 at the pressure reducing position 25c where the primary port and the drain port communicate with each other, and it is not after towing, so the processing is ended as it is.

  In step S17, the timer value T is decreased from the current value by ΔT.

  In step S18, it is determined whether the timer value T has become zero or less, that is, whether a predetermined waiting time has elapsed since the start of the precharge operation. When the timer value T is smaller than zero, a predetermined waiting time has elapsed since the start of the precharge operation, and the primary pressure Ppri has not risen to the predetermined pressure. It is determined that it is after being towed, and the process proceeds to step S19 to execute post-towed control for sending the step motor 27 to a position on the Hi side until the primary pressure Ppri reaches a predetermined pressure. Details of the control after tow will be described later.

  If the timer value T is not less than or equal to zero, since the predetermined waiting time has not yet elapsed since the start of the precharge operation, the process returns to step S16.

  FIG. 5 is a flowchart showing details of post-towed control executed in step S19 of FIG.

  First, in step S21, the target position of the step motor 27 is set to a predetermined position (second target position) corresponding to the gear ratio on the Hi side with respect to the current position (first target position), and directed toward the second target position. Then, the step motor 27 is sent. The second target position is a position corresponding to a speed ratio that does not impair the startability of the vehicle, and corresponds to a speed ratio of about 1.5, for example.

  In step S22, it is determined whether the current position of the step motor 27 is on the Hi side with respect to the second target position. If it is on the Hi side, if the step motor 27 is further sent to the Hi side, the starting performance is deteriorated, so the process proceeds to step S24 and the step motor 2 is stopped at the current position. In order to stop the step motor 27 at the current position, in step S24, the target position of the step motor 27 is updated to the current position, that is, the deviation between the target position and the current position is made zero, thereby causing the step motor 27 to instantaneously Stop in position.

  If the current position of the step motor 27 is not on the Hi side with respect to the second target position, the process proceeds to step S23 to determine whether the primary pressure Ppri has reached a predetermined pressure. If the primary pressure Ppri has reached the predetermined pressure, it is determined that the line pressure port and the primary pressure port are in communication with each other, so the routine proceeds to step S24, where the step motor 27 is stopped at the current position. The method of stopping the step motor 27 at the current position is as described above. If the primary pressure Ppri has not reached the predetermined pressure, the process returns to step S21, and the step motor 27 is further sent to the Hi side.

  Thus, when the engine is started after being towed, the step motor 27 is sent to the Hi side until the primary pressure Ppri reaches a predetermined pressure, and when the primary pressure Ppri reaches the predetermined pressure, the position at that time is reached. The step motor 27 stops.

  FIG. 6 is a time chart showing a state when the engine 5 is started after being towed. For comparison, the case where it is not after towing is also shown by a broken line.

  When the ignition key is turned from OFF to ON at time t1, the engine 5 is started, and an initialization operation for sending the step motor 27 to the lowest position is performed.

  After completion of the initialization operation of the step motor 27, the step motor 27 is sent to the first target position set according to the transmission oil temperature TMP (time t2), and the precharge of the hydraulic pressure to the primary pulley chamber 2c is started. .

  When not being towed, the primary pressure Ppri rises to a predetermined pressure until a predetermined waiting time (timer value T) elapses as indicated by a broken line, but after being towed, the drain port and the primary pressure port communicate with each other. Since the shift control valve 25 is at the position, the primary pressure is drained even if the precharge operation is performed, and the primary pressure Ppri does not rise to the predetermined pressure even if a predetermined waiting time elapses as shown in FIG.

  In this example, it is determined that the vehicle has been towed at time t3 when a predetermined waiting time has elapsed, and post-towed control is executed. In the post-towed control, the target position of the step motor 27 is set to a second target position that corresponds to the gear ratio on the Hi side further than the current position, and the step motor 27 is sent toward the second target position.

  When the step motor 27 is sent to the Hi side, the speed change link 26 swings about the connection point with the movable flange 2b to displace the speed change control valve 25, and the line pressure port and the primary pressure port are in communication with each other. Displace to the pressure position 25b. When the shift control valve 25 is displaced to the pressure increasing position 25b until the primary pressure Ppri starts to increase, the current position of the step motor 27 is set to the target position at time t4 when the primary pressure Ppri reaches the predetermined pressure, and the step motor 27 Stop immediately. As a result, the step motor 27 is sent to the Hi side more than necessary, and it is avoided that the gear ratio at the time of starting becomes the Hi side and the startability is deteriorated.

  The effects of performing the above control are summarized as follows.

  The transmission controller 12 sets the position corresponding to the gear ratio on the Hi side as the first target position as the transmission oil temperature TMP is lower (S13), and after starting the engine, sets the step motor 27 to the target position (first target position). (Position) (S14). If the primary pressure Ppri does not reach the predetermined pressure before the predetermined waiting time elapses after the step motor 27 is sent to the target position, the step motor 27 is further adapted to the gear ratio on the Hi side from the target position. It sends it to the position to perform (S21).

  The step motor 27 is sent to the Hi side by a predetermined amount according to the transmission oil temperature TMP when the vehicle engine is started (when the key is turned on), and the step motor 27 is on the Hi side when performing the towing determination. Even during the time, the primary pressure Ppri is likely to rise during the precharge operation, and it can be prevented that the primary pressure Ppri is erroneously determined as being after being towed but not being towed. If control after towing is performed due to erroneous determination, the step motor 27 is unnecessarily sent to the Hi side and the startability deteriorates. However, according to the present invention, deterioration of the startability due to such erroneous determination can be avoided. (Effect of invention of Claim 1).

  Since the predetermined waiting time is set longer as the transmission oil temperature TMP is lower (S15, FIG. 4), even if the rise of the primary pressure Ppri is somewhat delayed at a low temperature, the predetermined waiting time is not obtained after being pulled. The primary pressure Ppri rises until the time elapses, and it is possible to further prevent erroneous determination that it is after towing but not after towing (the effect of the invention of claim 2).

  Further, when the primary pressure Ppri reaches a predetermined pressure by sending the step motor 27 further to the position corresponding to the gear ratio on the Hi side in the post-traction control, the primary pressure Ppri is set to the predetermined pressure. It stops at the position when it reached (S24). Thereby, the position of the step motor 27 is not sent to the Hi side more than necessary, and the deterioration of the startability due to the control after being pulled can be minimized (the effect of the invention according to claim 3).

  At this time, when the primary pressure Ppri reaches a predetermined pressure, the step motor 27 is stopped by setting the position of the step motor 27 to the target position. Therefore, the step motor 27 is moved when the primary pressure Ppri reaches the predetermined pressure. It is possible to immediately stop at the position (effect of the invention according to claim 4).

  The embodiment of the present invention has been described above, but the above embodiment is merely an example of application of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configuration of the above embodiment.

1 is a schematic configuration diagram of a belt-type continuously variable transmission including a transmission control device according to the present invention. It is a block diagram of a transmission controller and a shift control hydraulic circuit. It is the flowchart which showed the content of the control which a transmission controller performs at the time of engine starting. It is the flowchart which showed the content of the control after tow which a transmission controller performs. It is a table for setting a timer value from transmission oil temperature. It is the time chart which showed a mode when an engine is started after towed.

Explanation of symbols

2 Primary pulley 2a Fixed flange 2b Movable flange 12 Transmission controller 25 Shift control valve 26 Shift link 27 Step motor (shift actuator)

Claims (4)

A shift control valve for controlling the primary pressure supplied to the primary pulley is connected to the center of the shift link, a movable flange of the primary pulley is connected to one end of the shift link, and the shift shifts to a position corresponding to the target gear ratio. By connecting an actuator to the other end of the speed change link, a mechanical feedback mechanism for controlling the speed change ratio to the target speed change ratio, and the movable flange is urged toward the opposite fixed flange, and the speed change ratio at the time of towing And an urging means for making the Hi side higher than the maximum Lo, and a transmission control device for a continuously variable transmission,
Means for setting the position corresponding to the gear ratio on the Hi side as the oil temperature of the transmission as the target position of the transmission actuator;
Means for moving the variable speed actuator to the target position after starting the engine;
When the primary pressure does not reach the predetermined pressure before the predetermined waiting time elapses after the shift actuator is moved to the target position, the shift actuator is further adapted to the gear ratio on the Hi side from the target position. Means for moving toward the position to be
A transmission control device for a continuously variable transmission.   The shift control device for a continuously variable transmission according to claim 1, wherein the predetermined waiting time is set longer as the oil temperature of the transmission is lower.   When the primary pressure reaches the predetermined pressure by moving the speed change actuator further toward a position corresponding to the gear ratio on the Hi side, the primary pressure reaches the predetermined pressure when the primary pressure reaches the predetermined pressure. The shift control device for a continuously variable transmission according to claim 1 or 2, further comprising a shift actuator stop means for stopping at the position.   The speed change actuator stop means stops the speed change actuator by setting the position of the speed change actuator when the primary pressure reaches the predetermined pressure as a target position of the speed change actuator. A transmission control device for a continuously variable transmission.