JP2020026811A - Shift control device for continuously variable transmission - Google Patents

Abstract

To prevent a vehicle behavior from becoming unstable without causing a sudden change of a vehicle longitudinal acceleration generated in association with gear shift when there is unexpected intervention of the gear shift during travel.SOLUTION: A shift control device for a belt type continuously variable transmission CVT includes a variator 4, and a CVT control unit 8, the CVT control unit 8 having a shift speed criteria setting part 8a, and a shift speed control part 8b. The shift speed criteria setting part 8a sets shift speed criteria B for restricting the upper limit speed of a shift speed where the gear ratio of the variator 4 changes so that the vehicle longitudinal acceleration generated in association with the gear shift does not exceed a predetermined value. The shift speed control part 8b controls the upper limit speed of the shift speed to be equal to or lower than the shift speed criteria B during shift control to control the gear ratio of the variator 4.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a shift control device for a continuously variable transmission mounted on a vehicle.

  BACKGROUND ART Conventionally, a belt-type continuously variable transmission that can improve the reliability of a product by effectively performing a fail-safe operation of a hydraulic oil supply / discharge valve has been known (for example, see Patent Literature 1). In this belt-type continuously variable transmission, the hydraulic oil supply / discharge valve opens and the hydraulic control device supplies hydraulic oil of a predetermined supply hydraulic pressure Pin to the movable sheave at the time of a change in the gear ratio. Thereby, the movable sheave is driven to control the clamping force of the belt. Further, when there is a high possibility that the operation of holding the open state of the hydraulic oil supply / discharge valve fails, the upper limit value of the speed change speed of the gear ratio is set.

JP 2013-137105 A

  In the above-mentioned conventional belt-type continuously variable transmission, since the upper limit of the shift speed is set after a sign of abnormality has occurred in the hydraulic oil supply / discharge valve, the shift speed is restricted by setting the upper limit. There is a possibility that the shift speed may exceed the regulation value in time. As a result, there is a problem in that if a shift is suddenly intervened during traveling, the vehicle behavior becomes unstable due to a sudden change in the longitudinal acceleration of the vehicle caused by the shift.

  The present invention has been made in view of the above problem, and when a shift is unexpectedly intervened during traveling, the vehicle longitudinal acceleration caused by the shift does not suddenly change, and the vehicle behavior becomes unstable. The purpose is to prevent.

In order to achieve the above object, the present invention includes a continuously variable transmission mechanism interposed between a driving source for traveling and drive wheels, and a transmission controller for controlling a speed ratio of the continuously variable transmission mechanism.
In the transmission control device for a continuously variable transmission, the transmission controller includes a transmission speed criterion setting unit and a transmission speed control unit.
The shift speed criterion setting unit sets a shift speed criterion that regulates the upper limit speed of the shift speed at which the speed ratio of the continuously variable transmission mechanism changes so that the longitudinal acceleration of the vehicle generated by the shift does not exceed a predetermined value.
The shift speed control unit controls the upper limit speed of the shift speed to be equal to or less than the shift speed criterion during the shift control for controlling the shift ratio of the continuously variable transmission mechanism.

  In this way, the control is performed such that the shift speed does not always exceed the shift speed criterion during the shift control. As a result, when a shift is suddenly intervened during traveling, the longitudinal acceleration of the vehicle caused by the shift does not exceed a predetermined value, and the vehicle behavior can be prevented from becoming unstable.

1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which a shift control device for a continuously variable transmission according to a first embodiment is applied. FIG. 9 is a shift schedule diagram illustrating an example of a D-range continuously variable shift schedule used when a continuously variable shift control in an automatic shift mode is performed by a variator. FIG. 1 is a schematic configuration diagram illustrating a transmission control device according to a first embodiment. 4 is a flowchart illustrating a flow of a shift control process by a shift speed restriction executed by a shift speed criterion setting unit and a shift speed control unit of the CVT control unit according to the first embodiment. It is a map figure showing an example of a shift speed criteria map used for calculation of a difference thrust regulation value in shift control processing which controls a shift speed. It is explanatory drawing which shows the coast deceleration turning scene. 4 is a time chart illustrating characteristics of a gear ratio, an engine torque, a drive shaft torque, and an acceleration for explaining a mechanism of a sudden deceleration caused by a downshift. Hierarchy explanatory diagram showing that a series of parameters of vehicle deceleration → speed change ratio → differential thrust → oil pressure change → current change is established in a proportional / inverse proportion relationship in the vehicle hierarchy, unit hierarchy, variator system hierarchy and subsystem hierarchy. It is. 4 is a time chart illustrating characteristics of a gear ratio, an engine torque, a drive shaft torque, and an acceleration for explaining a shift speed limiting operation in the first embodiment.

  Hereinafter, an embodiment of a shift control device for a continuously variable transmission according to the present invention will be described based on a first embodiment shown in the drawings.

  The shift control device according to the first embodiment is applied to an engine vehicle equipped with a belt-type continuously variable transmission (an example of an automatic transmission) including a torque converter, a forward / reverse switching mechanism, a variator, and a final reduction mechanism. . Hereinafter, the configuration of the first embodiment will be described by dividing it into an “overall system configuration”, a “configuration of a shift control device”, and a “shift control process configuration based on shift speed regulation”.

[Overall system configuration]
FIG. 1 shows a drive system and a control system of an engine vehicle to which a shift control device for a continuously variable transmission according to a first embodiment is applied. Hereinafter, the overall system configuration will be described with reference to FIG.

As shown in FIG. 1, the drive system of the engine vehicle includes an engine 1, a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, a final reduction mechanism 5, and drive wheels 6, 6. I have.
Here, the belt-type continuously variable transmission CVT is configured by incorporating a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, and a final reduction mechanism 5 in a transmission case (not shown).

  The engine 1 can control the output torque by an engine control signal from outside, in addition to controlling the output torque by operating the accelerator by the driver. The engine 1 has an output torque control actuator 10 that performs torque control by a throttle valve opening / closing operation, a fuel cut operation, and the like. For example, during coast running by an accelerator foot release operation, fuel cut control is executed.

  The torque converter 2 is a starting element formed by a fluid coupling having a torque amplifying function and a torque fluctuation absorbing function. When a torque amplification function and a torque fluctuation absorbing function are not required, a lock-up clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 is provided. The torque converter 2 includes a pump impeller 23, a turbine runner 24, and a stator 26 as constituent elements. The pump impeller 23 is connected to the engine output shaft 11 via the converter housing 22. The turbine runner 24 is connected to the torque converter output shaft 21. Stator 26 is provided on the transmission case via one-way clutch 25.

  The forward / reverse switching mechanism 3 is a mechanism that switches the input rotation direction to the variator 4 between a forward rotation direction when traveling forward and a reverse rotation direction when traveling backward. The forward / reverse switching mechanism 3 includes a double pinion type planetary gear 30, a forward clutch 31 having a plurality of clutch plates, and a reverse brake 32 having a plurality of brake plates. The forward clutch 31 is hydraulically engaged by the forward clutch pressure Pfc when a forward travel range such as the D range is selected. The reverse brake 32 is hydraulically engaged by the reverse brake pressure Prb when selecting a reverse travel range such as the R range. Note that, when the N range (neutral range) is selected, the forward clutch 31 and the reverse brake 32 are both released by draining the forward clutch pressure Pfc and the reverse brake pressure Prb.

  The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44, and continuously changes a speed ratio (a ratio between variator input rotation and variator output rotation) by changing a belt contact diameter. It has a speed change mechanism. The primary pulley 42 includes a fixed pulley 42 a and a slide pulley 42 b disposed coaxially with the variator input shaft 40, and the slide pulley 42 b slides by a primary pressure Ppri guided to a primary pressure chamber 45. The secondary pulley 43 is composed of a fixed pulley 43a and a slide pulley 43b arranged coaxially with the variator output shaft 41. The slide pulley 43b slides by a secondary pressure Psec guided to a secondary pressure chamber 46. The pulley belt 44 is stretched over the sheave surface of the primary pulley 42 having a V shape and the sheave surface of the secondary pulley 43 having a V shape. The pulley belt 44 is formed of two sets of laminated rings in which a large number of annular rings are superimposed from inside to outside, and a punched plate material, and is provided with a large number of annularly laminated and attached by being sandwiched along the two sets of laminated rings. It is composed of elements. In addition, the pulley belt 44 may be a chain type belt in which a number of chain elements arranged in the pulley traveling direction are connected by a pin penetrating in the pulley axial direction.

  The final deceleration mechanism 5 is a mechanism that reduces the variator output rotation from the variator output shaft 41, provides a differential function, and transmits the differential function to the left and right drive wheels 6, 6. The final reduction mechanism 5 includes, as reduction gear mechanisms, an output gear 52 provided on a variator output shaft 41, an idler gear 53 and a reduction gear 54 provided on an idler shaft 50, and a final gear provided on an outer peripheral position of a differential case. And a gear 55. Further, as a differential gear mechanism, a differential gear 56 interposed between the left and right drive shafts 51, 51 is provided.

  As shown in FIG. 1, the control system of the engine vehicle includes a hydraulic control unit 7, a CVT control unit 8 (abbreviation "CVTCU"), and an engine control unit 9 (abbreviation "ECU"). The CVT control unit 8 and the engine control unit 9, which are electronic control systems, are connected by a CAN communication line 13 capable of exchanging information with each other.

  The hydraulic control unit 7 controls the primary pressure Ppri guided to the primary pressure chamber 45, the secondary pressure Psec guided to the secondary pressure chamber 46, the forward clutch pressure Pfc to the forward clutch 31, the reverse brake pressure Prb to the reverse brake 32, and the like. It is a unit that regulates pressure. The hydraulic control unit 7 includes an oil pump 70 that is rotationally driven by the engine 1 that is a driving source for traveling, and a hydraulic control circuit 71 that adjusts various control pressures based on a discharge pressure from the oil pump 70. . The oil pump may be used in combination with the oil pump 70 and the electric oil pump. The hydraulic control circuit 71 includes a line pressure solenoid valve 72, a primary pressure solenoid valve 73, a secondary pressure solenoid valve 74, a select solenoid valve 75, and a lock-up pressure solenoid valve 76. Each of the solenoid valves 72, 73, 74, 75, and 76 performs a pressure regulation operation based on a control command value (instruction current) output from the CVT control unit 8.

  The line pressure solenoid valve 72 regulates the discharge pressure from the oil pump 70 to the commanded line pressure PL according to the line pressure command value output from the CVT control unit 8. The line pressure PL is a base pressure for adjusting various control pressures, and is a hydraulic pressure that suppresses belt slip and clutch slip against torque transmitted to the drive system.

  The primary pressure solenoid valve 73 reduces and adjusts to the commanded primary pressure Ppri using the line pressure PL as the original pressure in accordance with the primary pressure command value output from the CVT control unit 8. The secondary pressure solenoid valve 74 adjusts the pressure to the secondary pressure Psec commanded using the line pressure PL as the original pressure in accordance with the secondary pressure command value output from the CVT control unit 8.

  The select solenoid valve 75 adjusts the pressure to the forward clutch pressure Pfc or the reverse brake pressure Prb commanded by using the line pressure PL as the original pressure in accordance with the forward clutch pressure command value or the reverse brake pressure command value output from the CVT control unit 8. I do.

  The lock-up pressure solenoid valve 76 regulates the lock-up clutch 20 to the LU command pressure Plu for engaging / slip engaging / releasing according to the command current Alu output from the CVT control unit 8.

The CVT control unit 8 performs line pressure control, shift control, forward / reverse switching control, lockup control, and the like. In the line pressure control, a command value for obtaining a target line pressure corresponding to the accelerator opening and the like is output to the line pressure solenoid valve 72. In the shift control, when the target gear ratio (target primary rotation Npri ^* ) is determined, a command value for obtaining the determined target gear ratio (target primary rotation Npri ^* ) is output to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. In the forward / reverse switching control, a command value for controlling engagement / disengagement of the forward clutch 31 and the reverse brake 32 is output to the select solenoid valve 75 in accordance with the selected range position. In the lockup control, an instruction current Alu for controlling the LU instruction pressure Plu for engaging / slipping / releasing the lockup clutch 20 is output to the lockup pressure solenoid valve 76.

  Sensor information and switch information from a primary rotation sensor 90, a vehicle speed sensor 91, a secondary pressure sensor 92, an oil temperature sensor 93, an inhibitor switch 94, a brake switch 95, and a turbine rotation sensor 96 are input to the CVT control unit 8. Further, sensor information from the secondary rotation sensor 97, the primary pressure sensor 98, the wheel speed sensor 99, and the like is input.

  The engine control unit 9 receives sensor information from the engine rotation sensor 12, the accelerator opening sensor 14, and the like. When requesting engine rotation information and accelerator opening information to the engine control unit 9, the CVT control unit 8 receives information on the engine rotation speed Ne and the accelerator opening APO via the CAN communication line 13. Further, when requesting engine torque information to the engine control unit 9, it receives, via the CAN communication line 13, information on the actual engine torque Te estimated and calculated in the engine control unit 9.

  FIG. 2 shows an example of the D-range continuously variable shift schedule used when the variator 4 executes the continuously variable shift control in the automatic shift mode when the D range is selected.

The “D-range shift mode” is an automatic shift mode in which the gear ratio is automatically and continuously changed according to the vehicle driving state. The shift control in the “D-range shift mode” is performed based on the operating point (DSP) in the D-range continuously variable shift schedule shown in FIG. VSP, APO) to determine the target primary rotational speed Npri ^* . Then, the control is performed by feedback control of the pulley hydraulic pressure to make the actual primary rotation speed Npri from the primary rotation sensor 90 coincide with the target primary rotation speed Npri ^* . The speed ratio is represented by the slope of the speed ratio line drawn from the zero operating point, as is apparent from the lowest speed ratio line and the highest speed ratio line of the D-range continuously variable transmission schedule. Therefore, determining the target primary rotational speed Npri ^{* based} on the operating point (VSP, APO) determines the target speed ratio of the variator 4.

That is, as shown in FIG. 2, the D-range continuously variable shift schedule used in the "D-range shift mode" includes a gear ratio width based on the lowest gear ratio and the highest gear ratio according to the operating point (VSP, APO). The gear ratio is set to be continuously changed within the range. For example, when the vehicle speed VSP is constant, when the accelerator pedal is depressed, the target primary rotational speed Npri ^* increases and shifts in the downshift direction, and when the accelerator return operation is performed, the target primary rotational speed Npri ^* decreases and increases. Shift in the shift direction. When the accelerator opening APO is constant, the vehicle shifts in the upshift direction when the vehicle speed VSP increases, and shifts in the downshift direction when the vehicle speed VSP decreases.

  The continuously variable shift during coast deceleration by the accelerator release operation is performed by downshifting to the lowest gear ratio as indicated by arrow A along the coast speed line (APO = 0) of the D range continuously variable shift schedule. This is performed by changing the vehicle speed VSP in the deceleration direction.

[Configuration of transmission control device]
FIG. 3 illustrates a shift control device according to the first embodiment. Hereinafter, a schematic configuration of the shift control device will be described with reference to FIG.

  As shown in FIG. 3, the drive system to which the shift control device is applied includes an engine 1 (driving drive source), a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, a final reduction mechanism 5, A drive wheel 6. The engine 1 drives an oil pump 70. The torque converter 2 has a lock-up clutch 20. The forward / reverse switching mechanism 3 has a forward clutch 31 and a reverse brake 32. The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44.

  As shown in FIG. 3, the control system to which the shift control device is applied includes a CVT control unit 8, an engine control unit 9, a primary pressure solenoid valve 73, and a secondary pressure solenoid valve 74. The CVT control unit 8 and the engine control unit 9 are connected by a CAN communication line 13. Information from a vehicle speed sensor 91, an inhibitor switch 94, a turbine rotation sensor 96, a wheel speed sensor 99, and the like is input to the CVT control unit 8. Information from the engine rotation sensor 12, the accelerator opening sensor 14, and the like is input to the engine control unit 9.

  The CVT control unit 8 has a shift speed criterion setting unit 8a and a shift speed control unit 8b.

  The shift speed criterion setting unit 8a regulates the upper limit speed of the shift speed at which the speed ratio of the variator 4 changes so that the vehicle longitudinal acceleration (vehicle deceleration) generated with the shift (downshift) does not exceed a predetermined value. The speed change criterion B is set.

  The shift speed criterion B (see the solid line characteristic in FIG. 5) is set to a value larger than the maximum value of the shift speed used during the normal shift (see the broken line characteristic in FIG. 5).

  The shift speed criterion B is set to a shift speed value of a downshift that suppresses vehicle deceleration that does not lead to lane departure behavior of the own vehicle when the variator 4 suddenly downshifts during deceleration turning and suddenly decelerates.

  As shown in FIG. 5, the shift speed criterion setting unit 8 a sets the relationship between the vehicle speed VSP and the shift speed criterion B by changing the transmission input rotation speed (primary rotation speed Npri) of the variator 4 in advance. It has a speed criteria map. Then, using the shift speed criterion map, the shift speed criterion B is set according to the vehicle speed VSP and the transmission input rotation speed (primary rotation speed Npri) at that time.

  The shift speed control unit 8b controls the upper limit speed of the shift speed to be equal to or lower than the shift speed criterion B during the shift control for controlling the shift ratio of the variator 4.

  Here, a difference thrust actual value ΔFact between the actual thrust of the primary pulley 42 and the actual thrust of the secondary pulley 43 is calculated. In parallel with the calculation of the actual difference thrust value ΔFact, the difference thrust regulation value ΔFcri between the primary pulley 42 and the secondary pulley 43 is calculated based on the speed change criteria B. Then, the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74, which are shift control valves, are controlled such that the actual difference thrust value ΔFact becomes equal to or less than the difference thrust regulation value ΔFcri.

  The primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74 are valves that control the pulley hydraulic pressure according to the magnitude of the current value. Accordingly, the actual current of the primary pressure solenoid valve 73 and the actual current of the secondary pressure solenoid valve 74 are monitored, and the actual difference thrust actual value ΔFact is estimated from the primary solenoid actual current and the secondary solenoid actual current. When the actual difference thrust value ΔFact exceeds the difference thrust regulation value ΔFcri, the command current to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve are adjusted so that the difference thrust actual value ΔFact becomes equal to or less than the difference thrust regulation value ΔFcri. The command current to 74 is corrected.

[Shift control processing configuration based on shift speed regulation]
FIG. 4 shows a flow of the shift control process by the shift speed regulation executed by the shift speed criterion setting unit 8a and the shift speed control unit 8b of the CVT control unit 8 of the first embodiment. Hereinafter, each step of FIG. 4 will be described. This processing is repeatedly performed in a predetermined control cycle.

  In step S1, following the start, the actual current of the primary pressure solenoid valve 73 and the actual current of the secondary pressure solenoid valve 74 are monitored, and the process proceeds to step S2.

  Here, information on the actual current of the primary pressure solenoid valve 73 is obtained by the primary pressure solenoid valve drive circuit. Similarly, information on the actual current of the secondary pressure solenoid valve 74 is obtained by a secondary pressure solenoid valve drive circuit.

  In step S2, following the monitoring of the PRISOL real current and the SECSOL real current in S1, a difference thrust actual value ΔFact is estimated from the PRISOL real current and the SECSOL real current, and the process proceeds to step S6.

  In step S3, following the start, the vehicle speed VSP and the primary rotation speed Npri are calculated, and the process proceeds to step S4. The processing in steps S3, S4, and S5 is performed in parallel with the processing in steps S1 and S2.

  Here, the primary rotation sensor 90 and the secondary rotation sensor 97 cannot be used if a sensor failure occurs. Therefore, the vehicle speed VSP uses the rotation speed estimated from the wheel speed sensor 99 (VDC vehicle speed) without using the secondary rotation speed Nsec from the secondary rotation sensor 97. The primary rotation speed Npri uses the turbine rotation speed Nt from the turbine rotation sensor 96 and the output from the inhibitor switch 94 without using the primary rotation speed Npri from the primary rotation sensor 90.

  In step S4, following the calculation of the vehicle speed VSP and the primary rotation speed Npri in S3, the transmission speed criterion map shown in FIG. 5 and the vehicle speed VSP and the primary rotation speed Npri are used to set the transmission speed criterion B at that time. Proceed to step S5.

  Here, as shown in FIG. 5, the "shift speed criterion map" is set such that the value of the shift speed criterion B decreases as the vehicle speed VSP increases. The primary speed Npri is set such that the lower the primary speed Npri, the smaller the value of the shift speed criterion B.

  In step S5, following the setting of the shift speed criterion B in S4, a difference thrust regulation value ΔFcri is calculated from the shift speed criterion B, and the process proceeds to step S6.

  Here, the calculation of the differential thrust regulation value ΔFcri from the shift speed criterion B uses the characteristic of the relationship between the shift ratio change speed and the differential thrust shown in FIG. , And the difference thrust regulation value ΔFcri.

  In step S6, following the estimation of the actual difference thrust value ΔFact in S2 and the calculation of the difference thrust regulation value ΔFcri in S5, it is determined whether or not the difference thrust actual value ΔFact exceeds the difference thrust regulation value ΔFcri. If YES (ΔFact> ΔFcri), the process proceeds to step S7, and if NO (ΔFact ≦ ΔFcri), the process proceeds to the end.

  In step S7, following the determination in step S6 that ΔFact> ΔFcri, the command current to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74 are set so that the actual differential thrust value ΔFact becomes equal to or less than the differential thrust regulation value ΔFcri. Correct the command current to, and proceed to the end.

  Next, the operation of the first embodiment is described as "background technology", "problem solving method", "shift control operation based on shift speed regulation", "reason for performing shift speed regulation control using differential thrust and current", "shift Speed limiting action "will be described separately.

[Background Art]
If the vehicle suddenly downshifts and suddenly decelerates during traveling in a coastal deceleration turning scene on a flat suburban road as shown in FIG. 6, the vehicle may deviate from the lane. In response to such an event, there is a demand to suppress a lane departure.

  As an analysis of the current situation, a mechanism in which a sudden deceleration occurs due to a downshift during a coast deceleration turning by an accelerator foot release operation will be described based on a time chart of FIG.

  It is assumed that there is a downshift in which the speed ratio change speed is high (downshift in which the gradient angle of the speed ratio characteristic is large) in a short time section between time t1 and time t2 shown in FIG. In this case, the engine torque decreases in the section between time t1 and time t2, and in the section between time t1 and time t2, a deceleration torque that is the sum of the course torque and the inertia torque is generated as the drive shaft torque. At this time, due to a downshift with a high speed ratio change speed, the input speed of the transmission sharply increases, and an inertia torque generated in proportion to the mass and the angular speed increases.

  Accordingly, the drive wheels start slipping (= braking lock) at the deceleration G (negative acceleration) due to the deceleration torque from time t1 caused by the downshift, and thereafter, the section until time t2 while gradually increasing the deceleration G Slip continues. In other words, during the period from time t1 to time t2, rapid deceleration occurs due to an increase in deceleration torque due to an inertia torque associated with a downshift with a high shift speed. Note that rapid deceleration does not occur with a deceleration torque corresponding to the course torque.

  On the other hand, the criterion definition of “rapid deceleration” can be defined by the lane departure amount determined by the timing at which the vehicle starts slipping due to the deceleration G caused by the downshift and the slip duration.

  However, unlike the stepped transmission mechanism, the variator has a variable transmission profile, and therefore cannot define the profile of the deceleration G. In other words, the criteria for “sudden deceleration” cannot be defined by uniform deceleration G.

  Issues will be clarified based on the above analysis of the current situation. An object of the present invention is to secure the stability of vehicle behavior even in a coast turning scene with an accelerator foot released in a variator system in which criteria cannot be defined by a uniform deceleration G.

[Problem solving measures]
(Criteria)
First, as for the criteria, as shown in FIG. 5, a shift speed at which the lane departure amount does not exceed the threshold is set for each of the vehicle speed and the PRI rotation speed. Since the differential thrust that generates the shift speed is all caused by the current of the PRI pressure SOL and the SEC pressure SOL, monitoring and regulating the actual current of the SOL can prevent lane departure.

(Detection)
The actual current of the PRI pressure SOL and the SEC pressure SOL is monitored, and the actual difference thrust that can be generated from the actual current is estimated. An abnormality is detected by comparing the actual difference thrust value with the difference thrust regulation value calculated from the shift speed criteria defined by the vehicle speed and the PRI rotation speed. Since the PRI rotation sensor and the SEC rotation sensor are SPF (Single Point of Failure), the PRI rotation speed uses the output of the TBN rotation sensor and INHSW, and the SEC rotation speed uses the rotation speed estimated from the VDC vehicle speed.

(treatment)
The command currents of the PRI pressure SOL and the SEC pressure SOL are corrected so that the actual value of the differential thrust estimated from the actual current is equal to or less than the differential thrust regulation value calculated from the shift speed criteria.

[Shift control action by shifting speed regulation]
The present invention employs the following means as means for solving the above problems.
The CVT control unit 8 includes a shift speed criterion setting unit 8a and a shift speed control unit 8b. The shift speed criterion setting unit 8a sets a shift speed criterion B that regulates the upper limit speed of the shift speed at which the speed ratio of the variator 4 changes so that the longitudinal acceleration of the vehicle caused by the shift does not exceed a predetermined value. The shift speed control unit 8b controls the upper limit speed of the shift speed to be equal to or lower than the shift speed criterion B during the shift control for controlling the shift ratio of the variator 4.

  Thus, instead of performing control to regulate the shift speed when there is a sign that the shift speed exceeds the shift speed criterion B or when the shift speed exceeds the shift speed criterion B, the shift speed does not always exceed the shift speed criterion B during the shift control. Is controlled as follows. As a result, when a shift is suddenly intervened during traveling, the longitudinal acceleration of the vehicle caused by the shift does not exceed a predetermined value, and the vehicle behavior can be prevented from becoming unstable.

  That is, when the shift control of the variator 4 is executed, the process proceeds from S1 to S2 in the flowchart of FIG. 4, and in S2, the actual difference thrust actual value ΔFact is estimated from the PRISOL actual current and the SECSOL actual current. In the flowchart of FIG. 4, the process proceeds from S3 to S4 to S5 in parallel with the process of proceeding from S1 to S2, and in S5, the differential thrust regulation value ΔFcri is calculated from the shift speed criterion B.

  In the next S6, following the estimation of the actual difference thrust value ΔFact in S2 and the calculation of the difference thrust regulation value ΔFcri in S5, it is determined whether the difference thrust actual value ΔFact exceeds the difference thrust regulation value ΔFcri. . If ΔFact> ΔFcri is determined in step S6, the process proceeds to step S7. In step S7, the command current to the primary pressure solenoid valve 73 and the secondary pressure solenoid are set so that the actual difference thrust value ΔFact becomes equal to or smaller than the difference thrust regulation value ΔFcri. The command current to the valve 74 is corrected. On the other hand, if ΔFact ≦ ΔFcri in the determination of S6, the process proceeds to the end, and returns to the start without correcting the command current to the primary pressure solenoid valve 73 and the command current to the secondary pressure solenoid valve 74.

[Why the speed regulation control can be performed using differential thrust and current]
As described above, during the shift control for controlling the speed ratio of the variator 4, when the upper limit speed of the shift speed is controlled to be equal to or less than the shift speed criterion B, the "shift speed" or "shift speed criterion B" is directly used. Instead, they use "differential thrust" and "current". The control output is also "command current correction" for the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. Hereinafter, the reason why the shift speed regulation control can be performed using “difference thrust” and “current” will be described with reference to FIG.

  First, in the vehicle hierarchy, the vehicle deceleration is proportional to the speed ratio change speed (= speed speed) of the variator 4. Therefore, the OK / NG area of the vehicle deceleration can be rewritten as the OK / NG area of the speed ratio change speed of the variator 4.

  Next, in the unit hierarchy, the speed ratio change speed of the variator 4 is proportional to the differential thrust between the primary pulley 42 and the secondary pulley 43 (thrust difference in the direction in which the pulley belt 44 is restrained). Therefore, the OK / NG area of the speed ratio change speed of the variator 4 can be rewritten as the OK / NG area of the differential thrust.

  Next, in the variator system hierarchy, the differential thrust between the primary pulley 42 and the secondary pulley 43 and the change in hydraulic pressure applied to the primary pulley 42 and the secondary pulley 43 are in a proportional relationship. Therefore, the OK / NG area of the differential thrust of the variator 4 can be rewritten as the OK / NG area of the hydraulic pressure change of the variator 4.

  Next, in the subsystem hierarchy, the hydraulic pressure change to the primary pulley 42 and the secondary pulley 43 and the current change to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74 are in inverse proportion. Therefore, the OK / NG area of the hydraulic pressure change of the variator 4 can be rewritten as the OK / NG area of the current change to the two solenoid valves 73 and 74.

  In particular, when the variator unit is a small unit, the variation is small, and the relationship shown in FIG. 8 is established in each layer as the variator unit characteristics. As described above, when the variator unit characteristic is a unit that satisfies the relationship shown in FIG. 8, control using the variator unit characteristic can be performed.

  That is, the fact that the speed ratio change speed of the variator 4 is proportional to the differential thrust between the primary pulley 42 and the secondary pulley 43 is used. In this case, the actual speed change information of the variator 4 can be obtained by estimating the actual difference thrust force value ΔFact. Further, by calculating the difference thrust regulation value ΔFcri, information on the shift speed limit value based on the shift speed criteria B can be obtained.

  Also, the fact that the difference between the difference in thrust between the primary pulley 42 and the secondary pulley 43 and the change in hydraulic pressure has a proportional relationship and the change in hydraulic pressure and the change in current have an inverse proportional relationship is used. In this case, by monitoring the primary solenoid actual current and the secondary solenoid actual current, the actual difference thrust actual value ΔFact can be estimated. If the actual difference thrust value ΔFact exceeds the difference thrust regulation value ΔFcri, the command current to both solenoid valves 73 and 74 is corrected so that the difference thrust actual value ΔFact becomes equal to or less than the difference thrust regulation value ΔFcri. Thus, control equivalent to controlling the upper limit speed of the shift speed of the variator 4 to be equal to or lower than the shift speed criteria B is executed.

[Shift speed limiting action]
A shift speed limiting operation for preventing sudden deceleration due to a downshift during an accelerator-release coast turning will be described with reference to a time chart of FIG.

  It is assumed that there is a downshift request with a high speed ratio change speed in a short time section between time t1 and time t2 shown in FIG. In this case, if the downshift is executed in accordance with the downshift request and the shift speed exceeds the shift speed criterion B, the shift speed is restricted to the shift speed based on the shift speed criterion B regardless of the downshift request.

  For this reason, the execution section of the downshift is extended from the time t1 to the section of the time t3, and the decreasing gradient of the engine torque in the section of the time t1 and the time t2 decreases more gradually than that in FIG. In the section of t3, a deceleration torque that is the sum of the course torque and the inertia torque is generated as the drive shaft torque, but the inertia torque decreases with the regulation of the shift speed.

  Therefore, the deceleration G due to the deceleration torque from the start time t1 of the downshift decreases, and the start of the slip of the drive wheel 6 (= brake lock) is prevented, and the slip of the drive wheel 6 is also prevented from continuing. . As a result, during the period from time t1 to time t3 during the turning of the accelerator foot while the coast is turning, the speed change is restricted to the speed change by the speed change criteria B, so that no rapid deceleration occurs, and the vehicle behavior of the own vehicle is also changed. Stable vehicle behavior without departing from the lane.

  As described above, the shift control device of the belt-type continuously variable transmission CVT according to the first embodiment has the following effects.

(1) A continuously variable transmission mechanism (variator 4) interposed between the driving source for driving (engine 1) and the driving wheels 6, and a transmission controller for controlling the speed ratio of the continuously variable transmission mechanism (variator 4). (CVT control unit 8) and a continuously variable transmission mechanism (belt-type continuously variable transmission CVT).
The transmission controller (CVT control unit 8) includes a shift speed criterion setting unit 8a and a shift speed control unit 8b,
The shift speed criterion setting unit 8a controls the upper limit speed of the shift speed at which the speed ratio of the continuously variable transmission mechanism (variator 4) changes so that the vehicle longitudinal acceleration generated with the shift does not exceed a predetermined value. Set criteria B,
The shift speed control unit 8b controls the upper limit speed of the shift speed to be equal to or lower than the shift speed criterion B during the shift control for controlling the shift ratio of the continuously variable transmission mechanism (variator 4).
For this reason, when a speed change suddenly intervenes during traveling, the vehicle longitudinal acceleration generated due to the speed change does not suddenly change, and the vehicle behavior can be prevented from becoming unstable.
That is, during the shift control, the shift speed is controlled not to always exceed the shift speed criterion B, and there is no delay in the control response due to the shift speed limiting control.

(2) The shift speed criterion setting unit 8a sets the shift speed criterion B to a value larger than the maximum value of the shift speed used during the normal shift.
Therefore, it is possible to prevent the shift speed from being limited during the normal operation.

(3) The speed change criterion setting unit 8a sets the speed change criterion B to a vehicle that does not reach the lane departure behavior of the own vehicle when the continuously variable transmission mechanism (variator 4) suddenly downshifts and decelerates during deceleration turning. Set the downshift speed value to suppress deceleration.
For this reason, when the continuously variable transmission mechanism (variator 4) suddenly downshifts and decelerates during deceleration turning, it is possible to prevent the lane departure behavior of the own vehicle.

(4) The transmission speed criterion setting unit 8a presets the relationship between the vehicle speed VSP and the transmission speed criterion B according to the magnitude of the transmission input rotation speed (primary rotation speed Npri) of the continuously variable transmission mechanism (variator 4). It has a shift speed criteria map (FIG. 5),
Using the shift speed criterion map, the shift speed criterion B is set in accordance with the vehicle speed VSP and the magnitude of the transmission input rotation speed (primary rotation speed Npri) at that time.
For this reason, it is possible to set an appropriate shift speed criterion B in accordance with a change in running conditions depending on the vehicle speed VSP and the magnitude of the transmission input rotation speed (primary rotation speed Npri).

(5) The continuously variable transmission mechanism (variator 4) has a primary pulley 42, a secondary pulley 43, and a pulley belt 44 stretched over both pulleys 42, 43.
The shift speed control unit 8b calculates a difference thrust actual value ΔFact between the actual thrust of the primary pulley 42 and the actual thrust of the secondary pulley 43 during the shift control for controlling the speed ratio of the continuously variable transmission mechanism (variator 4), The differential thrust regulation value ΔFcri between the primary pulley 42 and the secondary pulley 43 is calculated based on the speed criteria B, and the transmission control valve (the primary pressure solenoid valve 73 and the secondary The pressure solenoid valve 74) is controlled.
For this reason, in the case of a continuously variable transmission mechanism unit (variator unit) having a characteristic in which the speed change speed (speed ratio change speed) and the differential thrust are in a proportional relationship, the speed change speed is controlled by controlling the differential thrust between the primary pulley 42 and the secondary pulley 43. Regulation control can be performed.

(6) as a shift control valve, a primary pressure solenoid valve 73 and a secondary pressure solenoid valve 74 for controlling the pulley oil pressure according to the magnitude of the current value,
The speed change control unit 8b controls the speed ratio of the continuously variable transmission mechanism (variator 4).
The actual current of the primary pressure solenoid valve 73 and the actual current of the secondary pressure solenoid valve 74 are monitored, and an actual difference thrust actual value ΔFact is estimated from the primary solenoid actual current and the secondary solenoid actual current,
When the actual difference thrust value ΔFact exceeds the difference thrust regulation value ΔFcri, the command current to the primary pressure solenoid valve 73 and the secondary current solenoid valve 74 are controlled so that the difference thrust actual value ΔFact becomes equal to or less than the difference thrust regulation value ΔFcri. Is corrected.
Therefore, in the case of a continuously variable transmission mechanism unit (variator unit) having a characteristic in which the differential thrust and the current change are in inverse proportion or proportional relationship, the actual current thrust can be estimated by monitoring the actual current, and the instruction current can be estimated. Can be corrected to the shift speed limited output.

  The shift control device for a continuously variable transmission according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and changes and additions of the design are allowed without departing from the gist of the invention according to each claim of the claims.

  In the first embodiment, the shift speed criterion setting unit 8a sets the shift speed criterion B that regulates the upper limit speed of the downshift speed of the variator 4 so that the vehicle deceleration generated by the downshift does not exceed a predetermined value. I do. The example in which the shift speed control unit 8b controls the upper limit speed of the downshift speed to be equal to or less than the shift speed criterion B during the downshift control for controlling the speed ratio of the variator 4 has been described. However, the shift speed criterion setting section sets a shift speed criterion that regulates the upper limit speed of the variator upshift speed so that the vehicle acceleration generated by the upshift does not exceed a predetermined value. The shift speed control unit may be an example in which, during the upshift control for controlling the speed ratio of the variator 4, the upper limit speed of the upshift speed is controlled to be equal to or less than the shift speed criteria. In this case, for example, during traveling on a downhill, abrupt acceleration due to an upshift having a high shift speed as the vehicle speed increases can be suppressed, and the vehicle behavior can be stabilized.

  In the first embodiment, an example is shown in which the shift control device of the present invention is applied to an engine vehicle equipped with a belt-type continuously variable transmission CVT as an automatic transmission. However, the shift control device of the present invention may be applied to a vehicle equipped with a stepped transmission called Step AT, a vehicle equipped with a continuously variable transmission mechanism with a sub-transmission, or the like as an automatic transmission. The vehicle to which the present invention is applied is not limited to an engine vehicle, but may be applied to a hybrid vehicle having an engine and a motor as a driving source for driving, an electric vehicle having a motor as a driving source for driving, and the like.

1 engine (drive source for traveling)
CVT belt type continuously variable transmission 2 torque converter 3 forward / reverse switching mechanism 4 variator (continuously variable transmission mechanism)
5 Final deceleration mechanism 6 Drive wheel 7 Hydraulic control unit 73 Primary pressure solenoid valve 74 Secondary pressure solenoid valve 8 CVT control unit (transmission controller)
80a Gear speed criterion setting unit 80b Gear speed control unit 9 Engine control unit 12 Engine rotation sensor 14 Accelerator opening sensor 91 Vehicle speed sensor 94 Inhibitor switch 96 Turbine rotation sensor 99 Wheel speed sensor

Claims (6)

A continuously variable transmission mechanism interposed between the drive source for driving and the drive wheels, and a transmission controller for controlling a speed ratio of the continuously variable transmission mechanism;
The transmission controller has a shift speed criterion setting unit and a shift speed control unit,
The shift speed criterion setting unit sets a shift speed criterion that regulates an upper limit speed of a shift speed at which a speed ratio of the continuously variable transmission mechanism changes so that a vehicle longitudinal acceleration generated with the shift does not exceed a predetermined value. And
The shift speed control unit controls the upper limit speed of the shift speed to be equal to or less than the shift speed criterion during the shift control for controlling the speed ratio of the continuously variable transmission mechanism. Control device. The shift control device for a continuously variable transmission according to claim 1,
The shift control device for a continuously variable transmission, wherein the shift speed criterion setting unit sets the shift speed criterion to a value larger than a maximum value of a shift speed used during a normal shift. The shift control device for a continuously variable transmission according to claim 1 or 2,
The shift speed criterion setting unit is configured to reduce the shift speed criterion to a vehicle deceleration that does not lead to a lane departure behavior of the own vehicle when the continuously variable transmission mechanism suddenly downshifts and decelerates during deceleration turning. A speed change control device for a continuously variable transmission, wherein the speed change speed value is set to a predetermined speed value. The shift control device for a continuously variable transmission according to any one of claims 1 to 3,
The shift speed criterion setting unit has a shift speed criterion map in which a relationship characteristic between a vehicle speed and a shift speed criterion is preset according to a magnitude of a transmission input rotation speed of the continuously variable transmission mechanism.
A shift control device for a continuously variable transmission, wherein the shift speed criterion is set in accordance with the vehicle speed and the transmission input rotation speed at that time using the shift speed criterion map. The shift control device for a continuously variable transmission according to any one of claims 1 to 4,
The continuously variable transmission mechanism has a primary pulley, a secondary pulley, and a pulley belt stretched over both pulleys,
The shift speed control unit calculates a difference thrust actual value between an actual thrust of the primary pulley and an actual thrust of the secondary pulley during a shift control that controls a speed ratio of the continuously variable transmission mechanism, and the shift speed criterion is calculated. Calculating a differential thrust regulation value between the primary pulley and the secondary pulley based on the transmission, and controlling a shift control valve so that the actual differential thrust value is equal to or less than the differential thrust regulation value. Transmission control device. The shift control device for a continuously variable transmission according to claim 5,
The shift control valve includes a primary pressure solenoid valve and a secondary pressure solenoid valve that control a pulley hydraulic pressure according to a magnitude of a current value,
The speed change control unit controls the speed ratio of the continuously variable transmission mechanism during speed change control,
Monitor the actual current of the primary pressure solenoid valve and the actual current of the secondary pressure solenoid valve, estimate the actual thrust difference value from the primary solenoid actual current and the secondary solenoid actual current,
When the actual value of the differential thrust exceeds the regulated value of the differential thrust, the command current to the primary pressure solenoid valve and the command current to the secondary pressure solenoid valve are controlled so that the actual value of the differential thrust is equal to or less than the regulated value of the differential thrust. A shift control device for a continuously variable transmission, wherein the shift control device corrects an instruction current of the vehicle.