JP2019116955A - Route changeover control device - Google Patents

Abstract

To minimize downshift control which cannot control engagement pressure taking into consideration of a rotation number, to secure a drive force at a succeeding start, and to secure startability.SOLUTION: In a route changeover control device, a continuously variable transmission for continuously changing a gear change ratio, and a gear gear-change mechanism for charging the gear change ratio are arranged in parallel with each other, and a stepless gear change mode for transmitting torque from an input shaft to an output shaft via the continuously variable transmission, and a gear mode for transmitting the torque to the output shaft via the gear gear-change mechanism are selectively switchable by a combination of engagement and release of a plurality of advance clutches. When a vehicle speed is not higher than a prescribed vehicle speed during stepless gear change mode traveling, when the gear change ratio of the continuously variable transmission is not lower than a prescribed gear change ratio, and when a rotation number of the output shaft is not smaller than a prescribed rotation number, the control device performs a downshift while determining a progress degree of a gear change of the continuously variable transmission on the basis of the rotation number of the output shaft, and when the rotation number of the output shaft is smaller than the prescribed rotation number, the control device performs the downshift without taking into consideration the progress degree of the gear change based on the rotation number of the output shaft.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a route switching control device.

  Patent Document 1 discloses a torque transmission path between a first torque transmission path by a stepped transmission mechanism, a second torque transmission path by a continuously variable transmission (CVT), and the driven wheels of the stepped transmission mechanism and a vehicle. A synchro mechanism is engaged when in gear mode travel, and a synchro mechanism is released during belt mode travel, so that a torque transmission path is established between the first torque transmission path and the second torque transmission path. A vehicle is described which comprises a belt-type continuously variable transmission (WCVT) with start-up gear switching. In the technique described in Patent Document 1, when downshifting from the CVT path to the gear path at the time of a stop, progress of clutch-to-clutch shift from the rotation speed of the output shaft or input shaft of the WCVT detected by the rotation speed sensor Down shift control is performed while judging the situation.

JP, 2015-105708, A

  However, when the vehicle speed of the vehicle is low and the vehicle speed is low, detection of the rotation speed by the rotation speed sensor may be difficult. If it is difficult to detect the rotational speed by the rotational speed sensor, it is difficult to detect the rotational speed of the input shaft or the output shaft of the belt-type continuously variable transmission, which makes it difficult to properly control the engagement pressure of the clutch. On the other hand, when the downshift control is not performed, it becomes difficult to secure the driving force at the time of starting when starting next, that is, the starting performance.

  The present invention has been made in view of the above problems, and an object thereof is to minimize the downshift control which can not execute the control of the engagement pressure in consideration of the rotational speed, and to drive the vehicle at the next start. An object of the present invention is to provide a route switching control device capable of securing a starting force by securing a force.

  In order to solve the problems described above and achieve the above object, a path switching control device according to an aspect of the present invention continuously changes the transmission ratio to a power transmission path between an input shaft and an output shaft. A continuously variable transmission mode, in which a continuously variable transmission and a gear transmission mechanism that changes a gear ratio are provided in parallel, and transmits torque input from the input shaft to the output shaft via the continuously variable transmission. And a combination of engagement and disengagement of a plurality of forward clutches provided corresponding to the continuously variable transmission and the gear transmission mechanism, respectively, and a gear mode for transmitting the output shaft through the gear transmission mechanism. A path switching control device configured to be selectively switchable, wherein a vehicle speed is less than a predetermined vehicle speed during traveling in the continuously variable transmission mode, and a gear ratio in the continuously variable transmission is greater than a predetermined gear ratio, And of the output shaft When the number of revolutions is equal to or greater than a predetermined number of revolutions, downshifting is performed while determining the degree of progress of the shift in the continuously variable transmission based on the number of revolutions of the output shaft And a controller for performing the downshift without determining the degree of progress of the shift in the continuously variable transmission based on the number of rotations of the output shaft when the number of rotations is less than the number of rotations.

  According to the path switching control device according to the present invention, when the belt transmission ratio of the continuously variable transmission is equal to or greater than the predetermined transmission ratio, downshift control is performed even if the number of revolutions of the output shaft or the input shaft is small. By doing this, it is possible to minimize the downshift control that can not execute the control of the engagement pressure in consideration of the rotational speed, and secure the starting performance by securing the driving force at the time of starting next.

FIG. 1 is a configuration diagram showing a vehicle and an essential part of a hydraulic system and a control system according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining a control method according to an embodiment of the present invention. FIG. 3 is a timing chart for explaining the case where the condition of the rotational speed is established before the inertia phase start determination in the coast down control method according to the embodiment of the present invention. FIG. 4 is a timing chart for explaining the case where the condition of the rotational speed is satisfied after the inertia phase start determination in the coast down control method according to the embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following one embodiment, the same or corresponding parts are denoted by the same reference numerals. Further, the present invention is not limited by the embodiment described below.

  First, a route switching control device for a vehicle according to an embodiment of the present invention will be described. FIG. 1 is a configuration diagram showing a vehicle and a main part of a hydraulic system and a control system in this embodiment. In FIG. 1, a plurality of axes parallel to one another are developed and shown in one plane. As shown in FIG. 1, the power transmission device 10 is suitably adopted for a front engine / front drive (FF) type vehicle. In the power transmission device 10, the output of the engine 12 as a power source for traveling is transmitted from the torque converter 14 to the differential gear unit 18 via the automatic transmission 16 and distributed to the left and right drive wheels 20L and 20R. . The torque converter 14 includes a pump impeller 14 p coupled to a crankshaft of the engine 12 and a turbine impeller 14 t coupled to an input shaft 22 of the automatic transmission 16. The torque converter 14 is configured to transmit power via fluid and to be directly connectable via the lockup clutch 15. A mechanical oil pump 74 is provided on the pump impeller 14p. The mechanical oil pump 74 is rotationally driven by the engine 12 to output an oil pressure, and is used as an oil pressure source of the oil pressure control circuit 70 indicated by a broken line.

  The automatic transmission 16 includes an input shaft 22, a belt-type continuously variable transmission 24, a forward / reverse switching device 26, a gear transmission mechanism 28, an output shaft 30, and a reduction gear device 32. The input shaft 22 is integrally provided with a turbine shaft which is an output rotation member of the torque converter 14. The belt-type continuously variable transmission 24 is connected to the input shaft 22. The forward / reverse switching device 26 and the gear transmission mechanism 28 are connected to the input shaft 22 and provided in parallel with the belt type continuously variable transmission 24. The output shaft 30 and the reduction gear device 32 are common output rotary members of the belt type continuously variable transmission 24 and the gear transmission mechanism 28. The small diameter gear 34 of the reduction gear 32 meshes with the ring gear 36 of the differential gear 18. The gear transmission mechanism 28 corresponds to a gear transmission mechanism. In the automatic transmission 16 configured as described above, the output of the engine 12 is transmitted from the torque converter 14 to the output shaft 30 via the belt type continuously variable transmission 24. Alternatively, the output of the engine 12 is transmitted to the output shaft 30 via the forward and reverse switching device 26 and the gear transmission mechanism 28 without passing through the belt type continuously variable transmission 24. The driving force transmitted to the output shaft 30 is transmitted to the left and right drive wheels 20L and 20R via the reduction gear device 32 and the differential gear device 18.

  The automatic transmission 16 according to this embodiment includes a first power transmission path TP1 and a second power transmission path TP2. The first power transmission path TPl transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the forward and reverse switching device 26 and the gear transmission mechanism 28. The second power transmission path TP2 transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the belt type continuously variable transmission 24. The first power transmission path TP1 and the second power transmission path TP2 are switched according to the traveling state of the vehicle. The automatic transmission 16 disconnects the power transmission in the second power transmission path TP2 and the forward clutch Cl as a first disconnecting device for connecting and disconnecting (hereinafter referred to as disconnection) power transmission in the first power transmission path TP1. A clutch C2 for CVT travelling is provided as a second connection / disconnection device in contact. The first power transmission path TPl is further provided with a meshing type clutch Cs as a meshing type transmission device in series with the forward movement clutch C1 and the gear transmission mechanism 28, specifically, on the downstream side thereof. There is.

  The forward / reverse switching device 26 is mainly configured of a double pinion type planetary gear device. In the forward / reverse switching device 26, a carrier 26c is integrally connected to the input shaft 22, and a sun gear 26s is connected to a small diameter gear 42 coaxially rotatably disposed relative to the input shaft 22. On the other hand, while the ring gear 26r is selectively stopped by rotation via the reverse brake B1, the carrier 26c and the sun gear 26s are selectively connected via the forward clutch C1. When the forward clutch Cl is engaged and the reverse brake B1 is released, the input shaft 22 is directly connected to the small diameter gear 42, and a forward power transmission state is established. On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the small diameter gear 42 rotates in the reverse direction with respect to the input shaft 22, and a reverse power transmission state is established. When the forward clutch C1 and the reverse brake B1 are both released, a neutral state is established in which the power transmission is shut off. The forward clutch C1 and the reverse brake B1 are each a multi-plate friction engagement device in which a plurality of friction members are frictionally engaged by a hydraulic cylinder. In the friction engagement device, the C1 engagement hydraulic pressure Pc1 and B1 engagement hydraulic pressure Pb1 supplied to the hydraulic cylinders are respectively controlled in pressure by a linear solenoid valve or the like provided in the hydraulic operation control unit 72, and are engagement forces. The transfer torque capacity is continuously adjusted.

  The gear transmission mechanism 28 is provided coaxially with the small diameter gear 42, the large diameter gear 46 provided non-rotatably on the counter shaft 44 and engaged with the small diameter gear 42, and coaxially relative to the counter shaft 44 A small diameter idler gear 48 is provided. A meshing type clutch Cs is provided between the counter shaft 44 and the idler gear 48 so that power transmission between the counter shaft 44 and the idler gear 48 is disconnected. The meshed clutch Cs includes a synchromesh mechanism (synchronization mechanism) such as a synchronizer ring. When the clutch hub sleeve 50 is moved by the Cs switching hydraulic actuator 52 in the connecting direction which is the left direction in the drawing, the idler gear 48 can synchronously rotate with the counter shaft 44 via the synchronizer ring. When the clutch hub sleeve 50 is further moved, the idler gear 48 is connected to the countershaft 44 via spline teeth provided on the inner peripheral surface of the clutch hub sleeve 50. Although the Cs switching hydraulic actuator 52 is a hydraulic cylinder, the clutch hub sleeve 50 can also be moved using a feed screw mechanism or the like that is rotationally driven by an electric motor.

  The idler gear 48 described above meshes with a large diameter gear 58 provided on the output shaft 30. In the idler gear 48, when one of the forward clutch C1 and the reverse brake B1 is engaged and the meshing type clutch Cs is connected, the output of the engine 12 is switched from the input shaft 22 to the forward / reverse switching device 26, gear change mechanism 28, the idler gear 48, and the large diameter gear 58 sequentially transmit to the output shaft 30, and the first power transmission path TP1 is established. A gear change (speed reduction) is also performed between the small diameter idler gear 48 and the large diameter gear 58, and it can be considered that the gear transmission mechanism 28 is configured including the idler gear 48 and the large diameter gear 58.

  The belt type continuously variable transmission 24 includes a primary pulley 60 having a variable effective diameter provided on the input shaft 22, and a secondary pulley 64 having a variable effective diameter provided on a pulley rotation shaft 62 coaxial with the output shaft 30. And a transmission belt 66 wound between a pair of variable pulleys 60, 64. Power transmission is performed via friction between the pair of variable pulleys 60, 64 and the transmission belt 66. The pair of variable pulleys 60 and 64 respectively include hydraulic cylinders 60 c and 64 c as hydraulic actuators that apply a thrust for changing the V-groove width. For example, the primary hydraulic pressure Ppri supplied to the hydraulic cylinder 60c is controlled by the hydraulic operation control unit 72 of the hydraulic control circuit 70, and the V groove widths of the variable pulleys 60 and 64 are both changed. The effective diameter is changed, and the gear ratio γ2 is continuously changed. Further, the secondary hydraulic pressure Psec supplied to the hydraulic cylinder 64c is pressure-controlled by the hydraulic operation control unit 72, and the belt clamping pressure is adjusted so that the transmission belt 66 does not slip.

  The gear ratio γ1 of the first power transmission path TP1 determined by the gear ratio of the gear transmission mechanism 28 and the like is larger than the maximum value (maximum gear ratio γ2 max) of the gear ratio γ2 of the second power transmission path TP2. For example, the first power transmission path TP1 is used at the time of vehicle start or high load traveling, and is switched to the second power transmission path TP2 in accordance with the increase of the vehicle speed V, the decrease of the required driving force, and the like. When the vehicle is stopped, coast down control is performed to switch to the first power transmission path TP1 in preparation for the next start. The gear ratios γ1 and γ2 are ratios (Nt / No) of the turbine rotational speed Nt to the rotational speed (output rotational speed) No of the output shaft 30, and the gear ratios γ1 and γ2max are respectively greater than 1.0 and On the other hand, the output shaft 30 is decelerated and rotated. The turbine rotational speed Nt matches the rotational speed of the input shaft 22 (input rotational speed).

  The output shaft 30 is disposed so as to be relatively rotatable coaxially with the pulley rotation shaft 62, and the CVT travel clutch C2 provided between the output shaft 30 and the secondary pulley 64 prevents the output shaft 30 from rotating. Power transmission between the output shaft 30 and the secondary pulley 64 is disconnected. When the CVT travel clutch C2 is engaged, the output of the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the belt type continuously variable transmission 24, and the second power transmission path TP2 Is established. The CVT travel clutch C2 provided on the output side of the belt-type continuously variable transmission 24 is a multi-plate friction engagement device in which a plurality of friction members are frictionally engaged by a hydraulic cylinder, and supplied to the hydraulic cylinder The C2 engagement hydraulic pressure Pc2 is pressure-controlled by a linear solenoid valve or the like provided in the hydraulic operation control unit 72, whereby the engagement force, that is, the transfer torque capacity is continuously adjusted.

  The hydraulic operation control unit 72 is a valve body provided with an electromagnetic switching valve for switching an oil passage, an electromagnetic hydraulic control valve such as a linear solenoid valve for controlling hydraulic pressure, etc. The valve is electrically controlled. As a result, the primary hydraulic pressure Ppri, the secondary hydraulic pressure Psec, the C1 engagement hydraulic pressure Pc1, the C2 engagement hydraulic pressure Pc2, the B1 engagement hydraulic pressure Pb1, etc. are pressure controlled. The clutch hub sleeve 50 is axially moved via the Cs switching hydraulic actuator 52, and the meshing clutch Cs is engaged and disengaged. In addition to the mechanical oil pump 74, the hydraulic control circuit 70 is provided with an electric oil pump as needed. Alternatively, without providing the mechanical oil pump 74, the hydraulic pressure can be secured only by the electric oil pump.

  Such a power transmission device 10 for a vehicle is a controller that performs output control of the engine 12, shift control of the belt-type continuously variable transmission 24, switching control of the first power transmission path TP1 and the second power transmission path TP2, etc. An electronic control unit (ECU) 80 is provided. The electronic control unit 80 includes a so-called microcomputer having a CPU, a ROM, a RAM, an input / output interface and the like. The electronic control unit 80 executes signal processing in accordance with a program stored in advance in the ROM while utilizing the temporary storage function of the RAM, and divides it into a plurality of electronics for engine control, gear change control, etc. as necessary. It is configured using a controller.

  The electronic control unit 80 is connected to an engine speed sensor 82, a turbine speed sensor 84, an output speed sensor 86, an accelerator operation amount sensor 88, and the like. The electronic control unit 80 is a signal representing an engine rotational speed Ne, a turbine rotational speed Nt which is an input rotational speed, a rotational speed No of the output shaft 30 corresponding to the vehicle speed V, and an operation amount (acceleration operation amount) Acc of an accelerator pedal. And so on, various information necessary for various controls are provided. The engine rotation number sensor 82, the turbine rotation number sensor 84, and the output rotation number sensor 86 are, for example, electromagnetic pickups that generate a pulse by an electromotive force due to an electromagnetic induction action, and the electromotive force decreases when the rotation number decreases. It becomes difficult to occur. As rotation speed sensors 82, 84, and 86, other rotation speed sensors such as Hall element type and photoelectric type may be adopted. The output rotational speed sensor 86 measures the rotational speeds of other parts corresponding to the rotational speed of the output shaft 30 (output rotational speed No), such as the small diameter gear 34 of the reduction gear device 32 and the ring gear 36 of the differential gear device 18. You may detect as an output rotation speed.

  The electronic control unit 80 functionally includes a path switching control unit 90 for path switching control of the first power transmission path TP1 and the second power transmission path TP2. The path switching control unit 90 engages the first power transmission according to a predetermined switching condition by the clutch-to-clutch shift that engages one of the forward clutch C1 and the CVT travel clutch C2 during forward travel and releases the other. The path TP1 and the second power transmission path TP2 are switched. The switching conditions are determined in advance using, for example, operating conditions such as the vehicle speed V and the accelerator operation amount Acc. In this embodiment, the second power transmission path TP2 is used when the vehicle speed V of the vehicle is high or when the required driving force is small, and the vehicle is switched to the first power transmission path TP1 at the time of vehicle start or high load traveling. The route switching control unit 90 as a route switching control device functionally includes a coast down control unit 92. The coast down control unit 92 performs control processing according to the flowchart shown in FIG.

  Next, a control method by the route switching control device in the vehicle configured as described above will be described. FIG. 2 is a flowchart showing a control method of the route switching control device. In the control method of the path switching control device according to this embodiment, the vehicle travels from the continuously variable transmission mode traveling (belt mode traveling) by the second power transmission path TP2 to the gear transmission mechanism 28 by the first power transmission path TP1 (gear mode Can be switched to That is, while the vehicle is traveling in the belt mode, it is assumed that the vehicle speed V becomes equal to or lower than the predetermined vehicle speed for entering coast down control, and switching to gear mode traveling or stopping in belt mode is performed by coast down control. . The flowchart shown in FIG. 2 is started at a stage where the vehicle speed V becomes equal to or less than the predetermined vehicle speed for entering coast down control.

  As shown in FIG. 2, in step ST1, the path switching control unit 90 determines whether the gear ratio γ2 of the belt-type continuously variable transmission 24, that is, the gear ratio γ2 of the second power transmission path TP2 is equal to or greater than a predetermined value A. Determine Here, the predetermined value A to be compared may be the maximum gear ratio γ2max of the belt-type continuously variable transmission 24 or a predetermined gear ratio γ2t (γ2t <γ2max) less than the maximum gear ratio γ2max. When the path switching control unit 90 determines that the transmission ratio of the belt-type continuously variable transmission 24 is equal to or greater than the predetermined value A (step ST1: Yes), the process proceeds to step ST2.

  In step ST2, the path switching control unit 90 determines whether the number of rotations of the output shaft 30 is equal to or greater than a predetermined value B. When the path switching control unit 90 determines that the rotation speed of the output shaft 30 is equal to or more than the predetermined value B (step ST2: Yes), the process proceeds to step ST3.

  Coast down control is performed in step ST3. The coast down control in step ST3 is a coast down control known in the prior art. That is, the path switching control unit 90 performs downshift control by clutch-to-clutch shift while determining the progress degree of the shift in the belt-type continuously variable transmission 24 based on the rotation speed No of the output shaft 30. Specifically, based on the rotation speed of the output shaft 30 detected by the output rotation speed sensor 86, the path switching control unit 90 determines the progress of the clutch-to-clutch shift, and transmits the second power transmission to the power transmission path. The downshift control is performed to switch from the path TP2 to the first power transmission path TP1. Thereafter, the process proceeds to step ST4, and in the state switched to the first power transmission path TP1, the vehicle stops and the gear mode traveling is ended. In this case, when the vehicle restarts, it can be started by the gear mode traveling.

  On the other hand, when the path switching control unit 90 determines that the rotation number of the output shaft 30 is less than the predetermined value B in step ST2 (step ST2: No), the process proceeds to step ST5. Coast down control is performed in step ST5. The coast down control in step ST5 is a coast down control method according to an embodiment of the present invention. FIG. 3 is a timing chart for explaining the case where the condition of the rotational speed is satisfied before the inertia phase start determination in the coast down control according to this embodiment. FIG. 4 is a timing chart for explaining the case where the condition of the rotational speed is satisfied after the inertia phase start determination in the coast down control method according to the one embodiment.

  First, as shown in FIG. 3, when the shift sftoutex is switched from the second speed to the first speed (at the time of 2 → 1 shift output), switching from the second power transmission path TP2 to the first power transmission path TP1 Control, that is, coast down control is started. At this time, the C2 engagement hydraulic pressure Pc2 of the CVT travel clutch C2 decreases. Here, in order to make the CVT travel clutch C2 capable of being released, the C2 engagement hydraulic pressure Pc2 is corrected by the gear ratio at the 2 → 1 shift output time point. Thereafter, the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 temporarily increases. The engine speed Ne is assumed to be constant. Further, as the vehicle speed V decreases, the turbine rotational speed Nt decreases while substantially coinciding with the belt mode rotational speed Nogear [CV] in the belt mode traveling. Similarly, the gear mode rotational speed Nogear [1ST] in the gear mode traveling also decreases as the vehicle speed V decreases. The belt mode rotational speed Nogear [CV] is calculated by the product of the rotational speed No of the output shaft 30 and the belt gear ratio, and the gear mode rotational speed Nogear [1ST] is the product of the rotational speed No of the output shaft 30 and the gear mode gear ratio Calculated by

  After that, at the time when the negative condition is satisfied in the above-mentioned step ST2 (rotational speed condition time), the rotational speed No of the output shaft 30 is not detected and becomes 0 rpm. Accordingly, the belt mode rotational speed Nogear [CV] and The gear mode rotational speed Nogear [1ST] is also 0 rpm. Here, the rotational speed condition is a negative condition in step ST2, and is a condition under which the rotational speed No of the output shaft 30 is less than the predetermined value B (No <B). Here, the degree of progress of the shift based on the rotational speed No of the output shaft 30 is not considered.

  On the other hand, after the rotational speed condition time point, the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 is swept up after a surge is performed at a predetermined time point (time condition time point) where a constant pressure state is continued for a predetermined time or longer. Increase. Further, after the time condition time point, when the pressure condition (1) is satisfied (pressure condition (1) time point), the C2 engagement hydraulic pressure Pc2 of the CVT traveling clutch C2 starts the sweep-down. The pressure condition (1) is a condition under which the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 is equal to or higher than a first predetermined hydraulic pressure P1. Thereafter, when the pressure condition (2) is satisfied (pressure condition (2) time point), the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 outputs the maximum hydraulic pressure P1max. The pressure condition (2) is a condition under which the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 is equal to or higher than a second predetermined hydraulic pressure P2 which is larger than the first predetermined hydraulic pressure P1. Thus, the coast down control ends when the forward clutch C1 is engaged. Thus, the coast down control according to the embodiment at step ST5 ends.

  Also, unlike the case shown in FIG. 3, there are cases where the rotational speed condition is satisfied after the inertia phase start determination. As shown in FIG. 4, first, coast down control is started at the 2 → 1 shift output time point, and the C2 engagement hydraulic pressure Pc2 decreases. After the 2 → 1 shift output time point, the C2 engagement hydraulic pressure Pc2 is corrected by the gear ratio at the 2 → 1 shift output time point. On the other hand, the C1 engagement hydraulic pressure Pc1 temporarily increases. The engine speed Ne is assumed to be constant. Further, as the vehicle speed V decreases, the turbine rotational speed Nt decreases while substantially coinciding with the belt mode rotational speed Nogear [CV] in the belt mode traveling. Similarly, the gear mode rotational speed Nogear [1ST] in the gear mode traveling also decreases as the vehicle speed V decreases.

  After the inertia phase start determination is made (at the inertia phase start determination time), the turbine rotational speed Nt of the torque converter 14 increases. Here, the degree of progress of the shift based on the rotational speed No of the output shaft 30 is not considered. Further, the C2 engagement hydraulic pressure Pc2 is maintained at a predetermined hydraulic pressure from the rotational speed condition time point to the pressure condition (1) time point. The subsequent steps are the same as in the case shown in FIG. That is, at the time of pressure condition (1), the C2 engagement hydraulic pressure Pc2 starts to decrease. Thereafter, at the time of pressure condition (2), the C1 engagement hydraulic pressure Pc1 outputs the maximum hydraulic pressure P1max, the forward clutch C1 is engaged, and the coast down control is finished. Thus, the coast down control according to the embodiment at step ST5 ends.

  When the path switching control unit 90 determines in step ST1 that the transmission ratio of the belt-type continuously variable transmission 24 is less than the predetermined value A (step ST1: No), the process proceeds to step ST6. In step ST6, control to stop the belt mode traveling is performed. Specifically, the path switching control unit 90 prohibits the downshift to switch from the second power transmission path TP2 to the first power transmission path TP1, and causes the vehicle to stop in the belt mode. That is, when the vehicle traveling by the belt mode traveling suddenly decelerates, etc., the transmission ratio γ of the belt type continuously variable transmission 24 when the vehicle is stopped can not be returned to a size larger than the predetermined transmission ratio γt. When it is likely to stop, the coast down control unit 92 does not output various signals for executing the coast down control, prohibits the down shift, and stops in the belt mode. Thereafter, when the vehicle is stopped, the route switching control unit 90 cancels the downshift prohibition when the predetermined condition for the downshift control is satisfied, and the first power transmission from the second power transmission path TP2 is performed. A downshift to switch to path TP1 is performed. Thus, when the vehicle restarts, it can be started by the gear mode traveling.

  According to the embodiment of the present invention described above, the downshift control that can not execute the control of the engagement pressure in consideration of the rotational speed is minimized, and the driving force at the time of starting next is ensured to improve the starting performance It is possible to secure

  As mentioned above, although one Embodiment of this invention was described concretely, this invention is not limited to one above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention are possible. For example, the vehicle configurations described in the above-described embodiment are merely examples, and different vehicle configurations may be used as needed.

DESCRIPTION OF SYMBOLS 10 Power transmission device 80 Electronic control device 86 Output rotation speed sensor 90 Path switching control part (path switching control device)
92 Coast down control unit C1 Forward clutch C2 CVT travel clutch (second disconnection device)
TP1 1st power transmission path TP2 2nd power transmission path Nt Turbine rotational speed (input speed)
No Output RPM (vehicle speed)

Claims (1)

In the power transmission path between the input shaft and the output shaft, a continuously variable transmission for continuously changing the gear ratio and a gear transmission mechanism for changing the gear ratio are provided in parallel, and input from the input shaft A continuously variable transmission mode for transmitting the torque to the output shaft via the continuously variable transmission, and a gear mode for transmitting the output shaft to the output shaft via the gear transmission mechanism What is claimed is: 1. A path switching control device configured to be selectively switchable by a combination of engagement and release of a plurality of forward clutches provided corresponding to each mechanism.
When the vehicle speed is less than a predetermined vehicle speed during traveling in the continuously variable transmission mode, the gear ratio in the continuously variable transmission is a predetermined gear ratio or more, and the rotation speed of the output shaft is a predetermined rotation speed or more The downshift is performed while judging the progress of the shift in the continuously variable transmission based on the rotation speed of the output shaft, and when the rotation speed of the output shaft is less than a predetermined rotation speed, the rotation of the output shaft A control unit for performing the downshift without determining the degree of progress of the shift in the continuously variable transmission based on a number.

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