JP5102244B2 - Power transmission device - Google Patents

Description

  The present invention relates to a power transmission device, and more particularly to a power transmission device having a belt-type continuously variable transmission and a fluid pressure clutch capable of transmitting power from a power generation source mounted on the vehicle to the continuously variable transmission. .

  Conventionally, as a power transmission device connected to an engine as a power source mounted on a vehicle, a belt-type continuously variable transmission, and a forward / reverse switching mechanism disposed between the continuously variable transmission and the engine, So-called neutral control that lowers the torque transmitted from the engine to the continuously variable transmission by lowering the engagement pressure of the input clutch of the forward / reverse switching mechanism when the vehicle is stopped with the travel range selected. What can be executed is known (for example, see Patent Document 1). In this power transmission device, when the vehicle is traveling with the travel range selected, the working fluid (range pressure) regulated by the clutch modulator valve is approximately constant, and the forward / reverse switching mechanism is operated via the relay valve. Working fluid is supplied to the secondary cylinder from the secondary sheave control valve, which is supplied to the input clutch or reverse brake side, and adjusts the line pressure using the working fluid from the linear solenoid valve. The pressure is adjusted. Then, when the vehicle stops with the travel range selected, the relay valve is switched, and the garage shift control valve that regulates the working fluid (range pressure) from the clutch modulator valve using the working fluid from the linear solenoid valve. Is supplied to the input clutch or reverse brake side of the forward / reverse switching mechanism through the relay valve. Thereby, the engagement pressure of the input clutch of the forward / reverse switching mechanism can be reduced, and the torque transmitted from the engine to the continuously variable transmission can be reduced. Also, in this power transmission device, when the shift range is switched from the neutral range to the driving range by the driver for starting the vehicle in order to reduce fuel consumption and start shock, the working fluid from the garage shift control valve is moved back and forth. The relay valve is controlled so that it is supplied to the input clutch or reverse brake side of the advance switching mechanism, and then the working fluid regulated by the clutch modulator valve is supplied to the input clutch or reverse brake side at a predetermined timing. The relay valve is controlled.

JP 2004-183715 A

  By the way, during traveling of a vehicle equipped with the power transmission device as described above, the shift range may be switched from the traveling range to the neutral range by the driver and then switched to the traveling range again. Here, when the vehicle is running, the gear ratio set by the continuously variable transmission is smaller than that when the vehicle is stopped (on the high gear side), and the groove width of the secondary pulley is relatively narrow. In order to reduce the belt as much as possible, it is necessary to reduce the belt clamping pressure to some extent. However, when the linear solenoid valve is controlled so that the belt clamping pressure set by the secondary sheave control valve is reduced when switching from the neutral range to the driving range, the garage is controlled by the linear solenoid valve together with the secondary sheave control valve. The pressure of the working fluid supplied from the shift control valve to the input clutch or the like of the forward / reverse switching mechanism decreases, and the torque capacity may be insufficient, causing slippage in the input clutch or the like. On the other hand, if the working fluid regulated by the clutch modulator valve is supplied to the input clutch or the like at a relatively early stage after the shift range is switched from the neutral range to the travel range during vehicle travel, the clutch A large amount of working fluid is supplied to the fluid pressure clutch due to piston deformation, etc., and the flow rate of the working fluid supplied from the secondary sheave control valve to the secondary cylinder is insufficient, causing belt slippage in the continuously variable transmission. There is also a risk of it occurring.

  Accordingly, the present invention provides a power transmission device having a belt-type continuously variable transmission and a fluid pressure clutch capable of transmitting power from a power generation source mounted on the vehicle to the continuously variable transmission. The main purpose is to more appropriately control the continuously variable transmission and the fluid pressure clutch when the shift range is switched from the neutral range to the travel range.

  The power transmission device according to the present invention employs the following means in order to achieve the main object.

The power transmission device according to the present invention includes:
A first pulley provided on the drive-side rotary shaft, a second pulley provided on the driven-side rotary shaft, a belt spanned between the first and second pulleys, and the first pulley A continuously variable transmission having a first fluid pressure cylinder capable of changing the groove width and a second fluid pressure cylinder capable of changing the groove width of the second pulley, and a power generation source mounted on the vehicle. A pump that is driven and capable of sucking and discharging the working fluid from the working fluid reservoir, and a drive side of the continuously variable transmission from the power generation source when engaged by receiving the supply of the working fluid from the pump side A power transmission device having a fluid pressure clutch capable of transmitting power to a rotating shaft,
A solenoid valve capable of regulating and outputting the working fluid;
In order to adjust the clamping pressure of the belt of the continuously variable transmission, the working fluid from the pump side is regulated using the working fluid from the solenoid valve to adjust the first and second of the continuously variable transmission. A clamping pressure control valve capable of outputting to one of the fluid pressure cylinders;
A first pressure regulator that regulates the working fluid from the pump using the working fluid from the solenoid valve to generate the original pressure of the working fluid supplied to the first and second cylinders and the fluid pressure clutch. A valve,
A second pressure regulating valve capable of regulating the working fluid from the pump side using the working fluid from the solenoid valve and outputting it to the fluid pressure clutch side;
A first communication state in which working fluid can be supplied from the first pressure regulating valve to the fluid pressure clutch, and a second communication state in which working fluid can be supplied from the second pressure regulating valve to the fluid pressure clutch. A switching valve capable of setting the communication state;
When the shift range is switched from the neutral range to the travel shift range, the switching valve is controlled to set the second communication state, and the working fluid is supplied from the second pressure regulating valve. The target pressure of the working fluid output from the second pressure regulating valve so that the pressure of the working fluid supplied from the second pressure regulating valve to the fluid pressure clutch is increased while the fluid pressure clutch is engaged. Is set within a range of an upper limit value based on an upper limit clamping pressure allowed for the belt of the continuously variable transmission, the solenoid valve is controlled based on the target pressure, and the target pressure is set to the upper limit value or a predetermined value. Control means for controlling the switching valve so as to set the first communication state when the pressure is reached;
Is provided.

  In this power transmission device, the switching valve is controlled to set the second communication state when the shift range is switched from the neutral range to the travel shift range. Next, the hydraulic fluid is supplied from the second pressure regulating valve to engage the fluid pressure clutch, and at the same time, the pressure of the working fluid supplied from the second pressure regulating valve to the fluid pressure clutch is increased. The target pressure of the working fluid output from the pressure regulating valve is set within the upper limit range based on the upper limit clamping pressure allowed for the belt of the continuously variable transmission, and the solenoid valve is controlled based on the set target pressure Is done. As a result, the fluid pressure clutch is engaged and the pressure of the working fluid supplied to the fluid pressure clutch is reduced so that the durability of the belt is not impaired by a large stress acting on the belt of the continuously variable transmission. It can be raised. In this power transmission device, the target pressure of the working fluid output from the second pressure regulating valve is set to the upper limit after the second communication state is set by the switching valve in accordance with the switching from the neutral range to the traveling range. The switching valve is controlled so as to set the first communication state when the upper limit value based on the clamping pressure or the predetermined pressure is reached. As a result, the solenoid valve is controlled so that the pressure of the working fluid output from the second pressure regulating valve increases until the target pressure reaches the upper limit value based on the upper limit clamping pressure or a predetermined pressure. By increasing the engagement pressure of the fluid pressure clutch before switching from the two communication state to the first communication state, the pressure is reduced when the supply of the working fluid from the first pressure regulating valve to the fluid pressure clutch is started. It is possible to suppress the occurrence of belt slip in the continuously variable transmission due to the insufficient flow rate of the working fluid supplied from the control valve to the second fluid pressure cylinder. Further, even if the target pressure reaches the upper limit value based on the upper limit clamping pressure and the pressure of the working fluid output from the second pressure regulating valve cannot be increased, the first communication is changed from the second communication state at that stage. Since it is switched to the state, it is possible to suppress the occurrence of slipping in the fluid pressure clutch due to the lack of torque capacity. As a result, in this power transmission device, even if the shift range is switched from the neutral range to the driving range by the driver, the continuously variable transmission and the fluid pressure clutch are controlled more appropriately, and the belt of the continuously variable transmission. Therefore, it is possible to prevent the fluid pressure clutch and the belt from slipping well.

  Further, the control means, when the shift range is switched from the neutral range to the travel shift range while the vehicle is traveling in the state where the travel shift range is selected, The switching valve may be controlled so as to set the second communication state.

  Further, the control means limits the output to the power generation source until the fluid pressure clutch is engaged after the accelerator pedal is depressed in a state where the second communication state is set by the switching valve. May be required. Thereby, it is possible to satisfactorily prevent the fluid pressure clutch from slipping between the time when the accelerator pedal is depressed and the fluid pressure clutch is engaged while the second communication state is set. In this power transmission device, even if the restriction on the output from the power generation source is released when the second communication state is switched to the first communication state, the fluid pressure clutch has the first pressure regulating valve. Since the working fluid is sufficiently supplied, the occurrence of slippage of the fluid pressure clutch can be suppressed.

  Further, the upper limit value based on the upper limit clamping pressure may be set so as to decrease as the gear ratio of the continuously variable transmission decreases. In other words, the stress acting on the belt of the continuously variable transmission increases as the winding diameter decreases, that is, as the gear ratio is smaller (on the high gear side) if the force sandwiching the belt is the same. Therefore, if the upper limit value based on the upper limit clamping pressure (the upper limit value of the pressure of the working fluid output from the second pressure regulating valve) is set to be smaller as the speed ratio of the continuously variable transmission is smaller, the second While the working fluid is being supplied from the pressure regulating valve to the fluid pressure clutch, it is possible to suppress a large stress from acting on the belt of the continuously variable transmission, and to maintain good durability of the belt. Further, by setting the upper limit value in this way, it is possible to prevent the pressure rise of the working fluid from the second pressure regulating valve controlled simultaneously with the clamping pressure control valve by the linear solenoid valve from being restricted more than necessary. it can.

  Further, the control means controls the switching valve so as to set the second communication state in accordance with the switching from the neutral range to the traveling range, and then the input shaft of the fluid pressure clutch and the continuously variable The target pressure is set so that there is no difference in rotational speed from the drive side rotational shaft of the transmission, and the rotational speed of the input shaft of the fluid pressure clutch and the rotational speed of the drive side rotational shaft of the continuously variable transmission are The target pressure is set so that the pressure of the working fluid output from the second pressure regulating valve gradually increases from the substantially matched stage, and the accelerator is operated in the state where the second communication state is set by the switching valve. Requests that the power generation source limit the output until the rotation speed of the input shaft of the fluid pressure clutch and the rotation speed of the drive side rotation shaft substantially coincide with each other after the pedal is depressed. It may be. Thus, the engagement of the fluid pressure clutch and the increase of the engagement pressure can be more appropriately executed, and the output from the power generation source can be more appropriately limited.

  The travel range may include a forward travel range and a reverse travel range, and the fluid pressure clutch is arranged before and after being disposed between the power generation source and the continuously variable transmission. A forward clutch and a reverse clutch included in the advance switching mechanism may be used.

It is a schematic block diagram of the motor vehicle 10 which is a vehicle carrying the power transmission device 20 which concerns on one Example of this invention. 2 is a schematic configuration diagram of a power transmission device 20. FIG. FIG. 2 is a system diagram showing an outline of a hydraulic control unit 50 included in the power transmission device 20. 3 is a flowchart illustrating an example of an ND switching control routine executed by a shift ECU 21. It is explanatory drawing which shows an example of the map for an upper limit clamping pressure setting. The shift range, the accelerator opening, the control mode of the linear solenoid valve SLT, the target pressure P *, and the torque limiting state that limits the output torque of the engine 12 when the control routine at the time of ND switching is executed are the time. It is a time chart which shows a mode that it changes with progress.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a schematic configuration diagram of an automobile which is a vehicle equipped with a power transmission device according to an embodiment of the present invention. The automobile 10 of the embodiment shown in the figure is an engine 12 that is an internal combustion engine that outputs power by an explosion combustion of a mixture of hydrocarbon fuel such as gasoline or light oil and air, and an engine for controlling the operation of the engine 12. An electronic control unit (hereinafter referred to as “engine ECU”) 14, a brake electronic control unit (hereinafter referred to as “brake ECU”) 16 for controlling an electronically controlled hydraulic brake unit (not shown), a torque converter 23 and a belt type A step transmission (hereinafter referred to as “CVT”) 40 and a shift electronic control unit (hereinafter referred to as “shift ECU”) 21 for controlling these are connected to the crankshaft of the engine 12 and from the engine 12. And a power transmission device 20 for transmitting the power to the left and right drive wheels DW.

  As shown in FIG. 1, the engine ECU 14 includes an accelerator opening Acc from an accelerator pedal position sensor 92 that detects a depression amount (operation amount) of an accelerator pedal 91, a vehicle speed V from a vehicle speed sensor 99, and a rotation speed of a crankshaft. A signal from various sensors such as a rotational speed sensor (not shown) for detecting the engine, a signal from the brake ECU 16 and the shift ECU 21 and the like are input, and based on these signals, the engine ECU 14 Controls fuel injection valves, spark plugs, etc. The brake ECU 16 includes a master cylinder pressure detected by the master cylinder pressure sensor 94 when the brake pedal 93 is depressed, a vehicle speed V from the vehicle speed sensor 99, signals from various sensors (not shown), an engine ECU 14 and a shift ECU 21. The brake ECU 16 controls a brake actuator (hydraulic actuator) (not shown) and the like based on these signals.

  The transmission ECU 21 of the power transmission device 20 is housed inside the transmission case. The shift ECU 21 includes a shift range SR from the shift range sensor 96 that detects an operation position of the shift lever 95 included in a shift unit that allows selection of a desired shift range from a plurality of shift ranges, and a vehicle speed sensor 99. Vehicle speed V, signals from various sensors (not shown), signals from the engine ECU 14 and brake ECU 16, and the like are input, and the shift ECU 21 controls the torque converter 23, the CVT 40, and the like based on these signals. Here, in the automobile 10 of the embodiment, as a shift range of the shift lever 95, a parking range (P range) selected at the time of parking, a reverse range for reverse travel (R range), a neutral range (N range), In addition to the normal forward drive range (D range), the sports range (S range) that allows the driver to select any gear from a plurality of gears that are set in advance, upshift instruction position And downshift instruction position is prepared.

  The engine ECU 14, the brake ECU 16, and the shift ECU 21 are configured as a microprocessor centered on a CPU (not shown). In addition to the CPU, a ROM that stores a processing program, a RAM that temporarily stores data, an input / output A port and a communication port (both not shown). The engine ECU 14, the brake ECU 16 and the speed change ECU 21 are connected to each other via a bus line or the like, and exchange of data necessary for control is executed at any time between these ECUs.

  FIG. 2 is a schematic configuration diagram of the power transmission device 20 mounted on the automobile 10. The power transmission device 20 shown in the figure is configured as a transaxle that is connected to the engine 12 that is disposed horizontally so that the crankshaft is substantially parallel to the left and right axles 84 connected to the drive wheels DW. , A converter housing 22a, a transaxle case 22b and a rear cover 22c coupled together, a torque converter 23 housed in the case 22, an oil pump 24, a forward / reverse switching mechanism 30, a CVT 40, and a gear mechanism. 80, a differential mechanism (differential gear) 82, and the like.

  The torque converter 23 includes an input-side pump impeller 23a connected to the crankshaft of the engine 12 and an output-side turbine runner 23b fixed to the input shaft 41 of the CVT 40, and further has a lock-up clutch function. is there. As shown in FIG. 2, the oil pump 24 includes a pump assembly 25 including a pump body 25a and a pump cover 25b, and an external gear 27 connected to the pump impeller 23a of the torque converter 23 via a hub. By rotating the external gear 27 with the power from the engine 12, the hydraulic oil (ATF) stored in the oil pan 29 (both see FIG. 3) is sucked through the strainer 28. The hydraulic pressure required by the CVT 40 and the forward / reverse switching mechanism 30 is generated, and hydraulic oil is supplied to lubricated parts such as various bearings.

  The forward / reverse switching mechanism 30 includes a double-pinion planetary gear mechanism 31, a brake (reverse clutch) B1 and a clutch (forward clutch) C1, which are hydraulic clutches. The planetary gear mechanism 31 includes a sun gear fixed to the input shaft 41 of the CVT 40, a ring gear, a pinion gear that meshes with the sun gear, and a carrier that supports the pinion gear meshed with the ring gear and is coupled to the primary shaft 42 of the CVT 40. The brake B1 can fix the ring gear of the planetary gear mechanism 31 to the transaxle case 22b and can be freely released. The clutch C1 can fix the carrier of the planetary gear mechanism 31 to the input shaft 41 (sun gear) and can be freely released. As a result, by disengaging the brake B1 and engaging the clutch C1, the power transmitted from the engine 12 to the input shaft 41 via the torque converter 23 is directly transmitted to the primary shaft 42 of the CVT 40 to It is possible to move forward. Further, by engaging the brake B1 and disengaging the clutch C1, it is possible to transmit power from the input shaft 41 to the primary shaft 42 of the CVT 40 while reversing the direction of rotation and to reverse the vehicle. Become. Further, it is possible to release the connection between the input shaft 41 (engine 12) and the primary shaft 42 (CVT 40) by releasing the engagement of both the brake B1 and the clutch C1.

  The CVT 40 includes a primary pulley 43 provided on a primary shaft 42 serving as a drive side rotation shaft, a secondary pulley 45 provided on a secondary shaft 44 serving as a driven side rotation shaft disposed in parallel with the primary shaft 42, and a primary pulley. 43, a belt 46 stretched between the groove of the secondary pulley 45 and the groove of the secondary pulley 45, a primary cylinder (first fluid pressure cylinder) 47 as a hydraulic actuator for changing the groove width of the primary pulley 43, and a secondary pulley And a secondary cylinder (second fluid pressure cylinder) 48 as a hydraulic actuator for changing the groove width of 45. The primary pulley 43 includes a fixed sheave 43a formed integrally with the primary shaft 42, and a movable sheave 43b supported by the primary shaft 42 so as to be slidable in the axial direction via a ball spline. 45 is urged in the axial direction by a fixed sheave 45a formed integrally with the secondary shaft 44, and supported by the secondary shaft 44 through a ball spline so as to be slidable in the axial direction and a return spring 49 as a compression spring. And a movable sheave 45b. The primary cylinder 47 is formed behind the movable sheave 43 b of the primary pulley 43, and the secondary cylinder 48 is formed behind the movable sheave 45 b of the secondary pulley 45. 3 is supplied to the primary cylinder 47 and the secondary cylinder 48 from the hydraulic control unit 50 illustrated in FIG. 3 so as to change the groove width between the primary pulley 43 and the secondary pulley 45. 23 and the power input to the primary shaft 42 via the forward / reverse switching mechanism 30 can be steplessly shifted and output to the secondary shaft 44. The power output to the secondary shaft 44 is transmitted to the left and right drive wheels DW via the gear mechanism 80 and the differential gear 82.

  As shown in FIG. 3, the hydraulic control unit 50 is connected to the oil pump 24 that is driven by the power from the engine 12 and sucks and discharges hydraulic oil from the oil pan 29. The hydraulic pressure required for the forward / reverse switching mechanism 30 can be generated and hydraulic oil can be supplied to and discharged from the brake B1 and the clutch C1. That is, the hydraulic control unit 50 is controlled based on the input torque of the CVT 40 estimated mainly from the accelerator opening Acc and the like, and regulates and outputs the hydraulic oil from the oil pump 24 side (pressure regulating valve not shown). Linear solenoid valve SLT, and the hydraulic oil driven by the linear solenoid valve SLT to adjust the pressure of the hydraulic oil from the oil pump 24 and supplied to the primary cylinder 47, the secondary cylinder 48, the clutch C1, the brake B1, etc. The primary regulator valve 51 that generates the line pressure PL, which is a pressure, and the brake pressure B1 and C1 of the forward / reverse switching mechanism 30 are adjusted (reduced) to generate a predetermined clutch holding pressure Pch. The line pressure PL is applied to the line pressure adjusting valve 52 and the movable sheave 43b. Further, the clutch supply pressure generated by the first shift control valve 53 and the line pressure adjusting valve 52 that can supply the hydraulic oil to the primary cylinder 47 and cut off the supply of the hydraulic oil to the primary cylinder 47 is further regulated. A duty solenoid valve DS1 that drives the first speed change control valve 53 using a modulator pressure Pmod from a pressure regulating valve (not shown) and hydraulic oil can be discharged from the primary cylinder 47 and drainage from the primary cylinder 47 can be shut off. A second shift control valve 54 and a duty solenoid valve DS2 that drives the second shift control valve 54 using the modulator pressure Pmod.

  Further, the hydraulic control unit 50 is driven by the linear solenoid valve SLT to adjust the hydraulic oil (line pressure PL) from the primary regulator valve 51 and supply it to the secondary cylinder 48 to adjust the clamping pressure of the belt 46 of the CVT 40. A belt clamping pressure control valve 55, a manual valve 56 that operates in conjunction with the shift lever 95, a switching valve (relay valve) 57 having first and second input ports 57a, 57b and an output port 57o, and a switching valve 57, a duty solenoid valve DSC and a solenoid valve SL for driving 57, an input port 58i and an output port 58o connected to the output port 52o of the line pressure adjusting valve 52, and a line pressure driven by the linear solenoid valve SLT. From adjustment valve 52 Hydraulic fluid control pressure by including a clutch pressure control valve 58 to be output. Electronic components such as the linear solenoid valve SLT, the duty solenoid valves DS1, DS2, DSC, and the solenoid valve SL included in the hydraulic control unit 50 are controlled by the shift electronic control unit 21.

  The manual valve 56 includes an input port 56i connected to the output port 57o of the switching valve 57, a D-range output port 56d connected to the hydraulic oil introduction portion of the clutch C1 of the forward / reverse switching mechanism 30, and a forward / reverse switching mechanism. 30 has an R range output port 56r connected to the hydraulic oil introduction portion of the brake B1, and a spool 56S that is slidable in the axial direction in conjunction with the shift lever 95. When the driver selects the P range or N range as the shift range, the spool 56S blocks communication between the input port 56i, the D range output port 56d, and the R range output port 56r. Further, when the driver selects the D range or the S range for sports driving as the shift range, the input port 56i is communicated only with the D range output port 56d by the spool 56S. The hydraulic oil can be supplied to the clutch (forward clutch) C1. Further, when the driver selects the R range as the shift range, the spool 56S causes the input port 56i to communicate with only the R range output port 56r, whereby the brake (reverse clutch) B1 of the forward / reverse switching mechanism 30 is connected. It becomes possible to supply hydraulic oil. As described above, the manual valve 56 can switch the supply destination of the hydraulic oil from the switching valve 57 in conjunction with the shift lever 95 according to the shift range selected by the driver. The flow path connecting the D-range output port 56d and the clutch C1 is connected to the drain port of the manual valve via a check valve.

  In addition to the first and second input ports 57a and 57b and the output port 57o, the switching valve 57 includes a signal pressure input port 57y connected to the duty solenoid valve DSC and a signal pressure input port 57y connected to the solenoid valve SL. The spool 57S is slidable in the axial direction, and includes a spring that urges the spool 57S in the axial direction. The first input port 57 a of the switching valve 57 is connected to the output port 52 o of the line pressure adjustment valve 52, and the second input port 57 b is connected to the output port 58 o of the clutch pressure control valve 58. In such a switching valve 57, if the duty solenoid valve DSC and the solenoid valve SL are controlled to move the spool 57S to the position shown in the right half of the figure, the first input port 57a and the output port 57o are connected. At the same time, the communication between the second input port 57 b and the output port 57 o is blocked (first communication state), whereby the hydraulic oil (clutch holding pressure Pch) from the line pressure adjusting valve 52 is manually transmitted via the switching valve 57. Supply to the input port 56i of the valve 56 becomes possible. Further, if the duty solenoid valve DSC and the solenoid valve SL are controlled to move the spool 57S to the position shown in the left half of the figure, the second input port 57b and the output port 57o are communicated with each other and the first input port. The communication between the output port 57o and the output port 57o is cut off (second communication state), so that the hydraulic oil from the clutch pressure control valve 58 (hereinafter referred to as the hydraulic oil pressure output from the clutch pressure control valve 58 is appropriately changed to “clutch”. The engagement pressure Pce ”) can be supplied to the input port 56i of the manual valve 56 via the switching valve 57.

  Next, referring to FIGS. 4 to 6, the shift range is switched from the D range to the N range by the driver while the automobile 10 is running while the D range is selected as the shift range. The operation of the power transmission device 20 when it is switched again to the D range after being performed will be described. FIG. 4 shows a predetermined state when the shift range is changed from the D range to the N range by the driver while the automobile 10 is running with the D range selected as the shift range. It is a flowchart which shows an example of the control routine at the time of ND switching performed repeatedly every time. In the embodiment, when the automobile 10 is traveling with the D range selected as the shift range, the switching valve 57 connects the first input port 57a and the output port 57o on the line pressure adjustment valve 52 side. The hydraulic fluid from the line pressure adjusting valve 52 is supplied to the input port 56i of the manual valve 56 in a communicating state, and the shift range is switched from the D range to the N range by the driver while the automobile 10 is running. Even if it is, the state of the switching valve 57 is maintained as it is. Further, when the driver switches the shift range from the D range to the N range while the vehicle 10 is traveling, the hydraulic oil in the clutch C1 is discharged through the check valve and the drain port, thereby engaging the clutch C1. The match is released.

  At the start of the ND switching control routine of FIG. 4, the CPU (not shown) of the shift ECU 21 selects the accelerator opening Acc from the engine ECU 14, the shift range SR from the shift range sensor 96, and the N range during travel. Estimated input torque Test separately calculated as torque input to the primary shaft 42 of the CVT 40, the rotational speed Nt of the turbine runner 23b of the torque converter 23, the rotational speed Np of the primary shaft 42 of the CVT 40, and the secondary shaft 44 of the CVT 40 Input processing of data necessary for the control such as the rotation speed Ns of is performed (step S100). The rotational speeds Nt, Np, and Ns are separately calculated based on detection values of rotational position sensors (not shown) provided for the turbine runner 23b, the primary shaft 42, and the secondary shaft 44, respectively.

After the data input process of step S100, it is determined whether or not a predetermined flag Fnd set to the value 1 is 0 when the shift range is switched from the N range to the D range while the automobile 10 is traveling. If the flag Fnd is 0 (step S110), it is further determined whether or not the shift range SR input in step S100 is the D range (step S120). When the shift range remains the N range, it is required for the hydraulic fluid supplied from the belt clamping pressure control valve 55 to the secondary cylinder 48 in order to suppress slippage of the belt 46 of the CVT 40. The pressure (required belt clamping pressure) is set as the required pressure Preq (step S180). In the embodiment, the relationship between the transmission ratio based on the estimated input torque Test, the rotation speed Np of the primary shaft 42 and the rotation speed Ns of the secondary shaft 44, and the required belt clamping pressure for suppressing the slip of the belt 46 is determined in advance. A belt clamping pressure setting map (not shown) is stored in a ROM (not shown) of the speed change ECU 21. In step S180, a map corresponding to the estimated input torque Test and the rotational speeds Np and Ns input in step S100 is obtained. The derived required belt clamping pressure is set as the required pressure Preq.

  Next, the belt 46 of the CVT 40 is allowed using the transmission ratio of the CVT 40 based on the rotational speeds Np and Ns input in step S100 and the upper limit clamping pressure setting map stored in the ROM (not shown) of the transmission ECU 21. The upper limit clamping pressure is set as the upper limit value Plim (step S190). FIG. 5 shows an example of the upper limit clamping pressure setting map. Here, the stress acting on the belt 46 of the CVT 40 is such that if the force sandwiching the belt 46 is the same, the smaller the winding diameter, that is, the smaller the gear ratio, as indicated by the two-dot chain line in FIG. The bigger it is). Based on this, the upper limit clamping pressure setting map of the embodiment keeps the durability of the belt 46 good by suppressing the large stress from acting on the belt 46 of the CVT 40 as shown by the solid line in FIG. Accordingly, the upper limit clamping pressure is set so as to decrease as the gear ratio of the CVT 40 decreases. In step S190, the upper limit clamping pressure derived from the upper limit clamping pressure setting map corresponding to the rotational speeds Np and Ns input in step S100 is set as the upper limit value Plim. If the required pressure Preq and the upper limit value Plim are thus set, the smaller of the required pressure Preq and the upper limit value Plim is set as the target pressure P * (step S200), and the current value corresponding to the target pressure P * is linear. A drive circuit (not shown) is controlled so as to be applied to the electromagnetic part of the solenoid valve SLT (step S210). Then, it is determined whether or not the above-mentioned flag Fnd is a value 1 (step S220). If the flag Fnd is a value 0 and the shift range is left at the N range, the processing after step S100 is performed again. Execute.

  On the other hand, if it is determined in step S110 that the flag Fnd is 0 and the shift range SR is determined to be the D range in step S120, the driver changes the shift range from the N range to the D range. It has been switched. In this case, after setting the above-mentioned flag Fnd to 1 (step S130), the switching valve 57 causes the second input port 57b and the output port 57o on the clutch pressure control valve 58 side to communicate with each other. The solenoid valve DSC and the solenoid valve SL are controlled (step S140). As a result, the hydraulic oil (clutch engagement pressure Pce) from the clutch pressure control valve 58 can be supplied to the input port 56i of the manual valve 56, that is, the clutch C1 via the switching valve 57. Next, it is determined whether or not the accelerator opening Acc input in step S100 is larger than 0, that is, whether or not the accelerator pedal 91 is depressed (step S150). If the accelerator pedal 91 is depressed, Then, it is determined whether or not the rotational speed Nt and the rotational speed Np input in step S100 do not match and the clutch C1 is in an unengaged state (step S160). If the clutch C1 is not engaged, an upper limit value of the throttle opening is set and transmitted to the engine ECU 14 to request the engine 12 to limit the torque output (step S170). In the embodiment, the upper limit value of the throttle opening is set using a map (not shown) according to a predetermined constant value or a gear ratio based on the rotation speed Np of the primary shaft 42 and the rotation speed Ns of the secondary shaft 44. Values are used. The engine ECU 14 that has received the upper limit value of the throttle opening controls the throttle valve so that the throttle opening is within the range of the received upper limit value. If it is determined in step S150 that the accelerator pedal 91 is not depressed, the processes in steps S160 and S170 are skipped.

  Subsequently, the pressure required for the hydraulic fluid output from the clutch pressure control valve 58 to engage the clutch C1 of the forward / reverse switching mechanism 30 is set as the required pressure Preq (step S182). In step S182 of the embodiment, the required pressure Preq is set so that relatively high hydraulic fluid is supplied from the clutch pressure control valve 58 to the clutch C1 in a short time immediately after the switching of the switching valve 57, and thereafter, the clutch The required pressure Preq is set using a relational expression for feedback control that eliminates the difference between the rotational speed Nt of the turbine runner 23b and the rotational speed Np of the primary shaft 42 that coincides with the rotational speed of the input shaft 41 connected to C1. Is done. Further, the clutch pressure control valve derived using the transmission ratio of the CVT 40 based on the rotational speeds Np and Ns input in step S100 and the upper limit pressure setting map (not shown) stored in the ROM (not shown) of the transmission ECU 21. The upper limit pressure of the hydraulic oil output from 58 is set as the upper limit value Plim (step S192). Here, in the upper limit pressure setting map (not shown), the pressure of the hydraulic fluid output from the belt clamping pressure control valve 55 driven by the hydraulic fluid from the linear solenoid valve SLT is the upper limit clamping pressure allowed for the belt 46. 5 is created in advance so as to define the relationship between the hydraulic oil pressure (clutch engagement pressure Pce) output from the clutch pressure control valve 58 and the transmission ratio of the CVT 40. It has the same tendency as the setting map. If the required pressure Preq and the upper limit value Plim are thus set, the smaller of the required pressure Preq and the upper limit value Plim is set as the target pressure P * of the clutch engagement pressure Pce (step S200), and the target pressure P * is set. A drive circuit (not shown) is controlled so that the corresponding current value is applied to the electromagnetic part of the linear solenoid valve SLT (step S210).

  After the process of step S210, it is determined whether or not the flag Fnd is 1 (step S220). If the flag Fnd is set to the value 1 in the previous step S130, an affirmative determination is made in step S220, and the target pressure P * set in step S200 is set by the clutch pressure control valve 58. It is determined whether it is less than the maximum possible pressure (the maximum value of the clutch engagement pressure Pce) or a switching pressure Pchg that is a constant value close to it (step S230), and if the target pressure P * is less than the switching pressure Pchg. Further, it is determined whether or not the target pressure P * set in step S200 is equal to or higher than the upper limit value Plim set in step S192 (step S240). If the target pressure P * is less than the upper limit value Plim, the processes after step S100 are executed again.

  When this routine is executed after the flag Fnd is set to the value 1 in step S130 as described above, it is determined that the flag Fnd is the value 1 in step S110. The process of S140 is skipped and the process of step S150 is executed. Then, an affirmative determination is made in step S150, and in step S160, the rotational speed Nt of the turbine runner 23b matches the rotational speed Np of the primary shaft 42, or the rotational speed difference between both falls within a predetermined range. When it is considered that the clutch C1 is engaged, the sum of the target pressure P * set at the previous execution of this routine and a predetermined rate value ΔP (positive value) is set as the required pressure Preq (step). S184). If it is assumed in step S160 that the clutch C1 is engaged and the process of step S184 is executed, the process of step S170 described above is not executed, so the output torque from the engine 12 at this stage is reduced. The restriction (torque limitation) is released. After the process of step S184, the processes of steps S192 to S230 described above are executed. If it is determined in step S230 that the target pressure P * is greater than or equal to the switching pressure Pchg, or if it is determined in step S240 that the target pressure P * is greater than or equal to the upper limit value Plim, the switching valve 57 Thus, the duty solenoid valve DSC and the solenoid valve SL are controlled so that the first input port 57a and the output port 57o on the line pressure adjusting valve 52 side are communicated with each other (step S250). As a result, the hydraulic oil (clutch holding pressure Pch) from the line pressure adjusting valve 52 can be supplied to the input port 56i of the manual valve 56, that is, the clutch C1 via the switching valve 57. Then, the above-mentioned flag Fnd is set to 0 (step S260), and this routine ends.

  FIG. 6 is a torque limit that limits the shift range, the accelerator opening, the control mode of the linear solenoid valve SLT, the target pressure P *, and the output torque of the engine 12 when the above-described ND switching control routine is executed. It is a time chart which shows a mode that the execution condition of changes with time progress. Here, the shift range is changed from the D range to the N range by the driver at time t0 in the figure while the automobile 10 is running with the D range selected as the shift range. Assume that the shift range is switched to the D range at time t1. When the shift range is switched from the N range to the D range at time t1, the duty solenoid valve DSC is connected so that the second input port 57b and the output port 57o on the clutch pressure control valve 58 side are communicated by the switching valve 57. The solenoid valve SL is controlled, and the hydraulic oil pressure (clutch engagement pressure Pce) output from the clutch pressure control valve 58 is within the range of the upper limit value Plim based on the upper limit clamping pressure allowed for the belt 46 of the CVT 40. The linear solenoid valve SLT is controlled so as to achieve the set target pressure P *, and hydraulic oil from the clutch pressure control valve 58 is supplied to the input port 56i of the manual valve 56, that is, the clutch C1 via the switching valve 57. It becomes like this. Further, when the driver depresses the accelerator pedal 91 after a short time from time t1 (time t2), execution of torque limitation for limiting the output torque from the engine 12 is started. Further, at the time t3 after the hydraulic oil is supplied from the clutch pressure control valve 58 to the clutch C1, the rotational speed Nt of the turbine runner 23b and the rotational speed Np of the primary shaft 42 substantially coincide with each other. When the clutch C1 is considered to be engaged, the target pressure P * of the clutch engagement pressure Pce is set so as to gradually increase at a constant rate value ΔP from that stage, and the output torque from the engine 12 is limited ( Torque limit) is released. When the target pressure P * reaches the upper limit value Plim at time t4, the duty solenoid valve DSC is connected so that the first input port 57a and the output port 57o on the line pressure adjustment valve 52 side are communicated by the switching valve 57. The solenoid valve SL is controlled so that the hydraulic oil (clutch holding pressure Pch) from the line pressure adjusting valve 52 is supplied to the input port 56i of the manual valve 56, that is, the clutch C1 via the switching valve 57. Become. If the upper limit value Plim is relatively large and the target pressure P * changes below the upper limit value Plim, when the target pressure P * reaches the switching pressure Pchg, the switching valve 57 causes the first pressure on the line pressure adjustment valve 52 side. Duty solenoid valve DSC and solenoid valve SL are controlled so that input port 57a and output port 57o communicate with each other.

  As described above, in the power transmission device 20 of the embodiment, after the shift range is switched to the N range while the automobile 10 is traveling with the D range selected, the N range to the D range is selected. When the switching is made again, the switching valve 57 is controlled so as to connect the second input port 57b and the output port 57o on the clutch pressure control valve 58 side (step S140). Next, when the hydraulic oil is supplied from the clutch pressure control valve 58, the clutch C1 of the forward / reverse switching mechanism 30 is engaged and output from the clutch pressure control valve 58 so that the pressure of the hydraulic oil supplied to the clutch C1 increases. The hydraulic oil target pressure P * is set within the range of the upper limit value Plim based on the upper limit clamping pressure allowed for the belt 46 of the CVT 40 (steps S182, S192, S200), and based on the set target pressure P *. Then, the linear solenoid valve SLT is controlled (step S210). As a result, the hydraulic oil supplied to the clutch C1 while engaging the clutch C1 of the forward / reverse switching mechanism 30 while preventing the durability of the belt 46 from being impaired by a large stress acting on the belt 46 of the CVT 40. It becomes possible to raise the pressure of the. Further, a request from the shifting ECU 21 until the clutch C1 is engaged after the accelerator pedal 91 is depressed in a state where the second input port 57b and the output port 57o on the clutch pressure control valve 58 side are communicated by the switching valve 57. The torque output from the engine 12 is limited according to (Step S170). As a result, the clutch C1 of the forward / reverse switching mechanism 30 is engaged between the time when the accelerator pedal 91 is depressed and the clutch C1 is engaged while the second input port 57b and the output port 57o are in communication with each other by the switching valve 57. It is possible to satisfactorily suppress the occurrence of slipping.

  In the power transmission device 20, the clutch pressure control valve is connected after the second input port 57 b and the output port 57 o on the clutch pressure control valve 58 side are communicated with each other by the switching valve 57 when switching from the N range to the D range. The first input port 57a and the output port 57o on the side of the line pressure adjustment valve 52 are at the stage when the target pressure P * of the hydraulic fluid output from 58 reaches the upper limit value Plim based on the upper limit clamping pressure or a predetermined switching pressure Pchg. Switching valve 57 (duty solenoid valve DSC and solenoid valve SL) is controlled so as to communicate with each other (steps S230 to S250). Thus, the linear solenoid valve SLT is controlled such that the hydraulic oil pressure (clutch engagement pressure Pce) output from the clutch pressure control valve 58 increases until the target pressure P * reaches the upper limit value Plim or the switching pressure Pchg. Therefore, the first input port 57a and the output port 57o on the line pressure adjusting valve 52 side are communicated from the state where the second input port 57b and the output port 57o on the clutch pressure control valve 58 side are communicated. By increasing the engagement pressure of the clutch C1 before switching to the state, the belt clamping pressure control valve 55 is started when the supply of hydraulic oil from the primary regulator valve 51 side, that is, the line pressure adjustment valve 52, to the clutch C1 is started. Belt in CVT 40 due to insufficient flow rate of hydraulic oil supplied to secondary cylinder 48 from Slip 6 can be prevented from being generated. Even if the target pressure P * reaches the upper limit value Plim based on the upper limit clamping pressure and the pressure of the hydraulic oil output from the clutch pressure control valve 58 cannot be increased, the line pressure is changed by the switching valve 57 at that stage. Since the first input port 57a and the output port 57o on the adjustment valve 52 side communicate with each other, it is possible to suppress the occurrence of slipping in the clutch C1 of the forward / reverse switching mechanism 30 due to insufficient torque capacity. Further, the state is switched from the state in which the second input port 57b and the output port 57o on the clutch pressure control valve 58 side communicate with each other to the state in which the first input port 57a and the output port 57o on the line pressure adjustment valve 52 side communicate with each other. Even when the restriction (torque limitation) of the output from the engine 12 is released, the hydraulic oil from the primary regulator valve 51 side, that is, the line pressure adjustment valve 52 is sufficiently supplied to the clutch C1 of the forward / reverse switching mechanism 30. Since it is supplied, the occurrence of slippage of the clutch C1 can be suppressed. As a result, in the power transmission device 20 of the embodiment, even if the shift range is switched from the D range to the N range by the driver while the automobile 10 is traveling, the CVT 40 and the forward / reverse switching are performed. It is possible to control the clutch C1 of the mechanism 30 more appropriately to prevent a large stress from acting on the belt 46 of the CVT 40 and to satisfactorily suppress slippage of the clutch C1 and the belt 46 of the forward / reverse switching mechanism 30. .

  Further, in the power transmission device 20 of the embodiment, the upper limit value Plim of the clutch engagement pressure Pce based on the upper limit clamping pressure is set so as to decrease as the gear ratio of the CVT 40 decreases (step S192). That is, the stress acting on the belt 46 of the CVT 40 increases as the winding diameter is smaller, that is, as the gear ratio is smaller (on the high gear side) if the force sandwiching the belt 46 is the same. Therefore, if the upper limit value Plim based on the upper limit clamping pressure is set to be smaller as the transmission ratio of the CVT 40 is smaller, the hydraulic oil is supplied to the belt 46 of the CVT 40 from the clutch pressure control valve 58 to the clutch C1. It is possible to keep the durability of the belt 46 good by suppressing the application of a large stress. Further, by setting the upper limit value Plim in this way, the pressure increase of the hydraulic oil from the clutch pressure control valve 58 controlled simultaneously with the belt clamping pressure control valve 55 by the linear solenoid valve SLT is not restricted more than necessary. can do.

  Further, in the power transmission device 20 according to the embodiment, the switching valve 57 is controlled so that the second input port 57b and the output port 57o on the clutch pressure control valve 58 side communicate with each other when switching from the N range to the D range. After that, the rotational speed difference between the rotational speed Nt of the turbine runner 23b that matches the rotational speed of the input shaft 41 connected to the clutch C1 of the forward / reverse switching mechanism 30 and the rotational speed Np of the primary shaft 42 of the CVT 40 is eliminated. Is set to the target pressure P * (step S182), and the pressure of the hydraulic oil output from the clutch pressure control valve 58 is constant from the stage where the rotational speed Nt of the turbine runner 23b and the rotational speed Np of the primary shaft 42 substantially coincide. The target pressure P * is set so as to gradually increase at the rate value (step S184). Further, after the accelerator pedal 91 is depressed in a state where the second input port 57b and the output port 57o on the clutch pressure control valve 58 side are communicated by the switching valve 57, the rotational speed Nt of the turbine runner 23b and the rotation of the primary shaft 42 are detected. The transmission ECU 21 requests the engine ECU 14 to limit the torque output of the engine 12 until the number Np substantially matches (steps S150 to S170). Thereby, the engagement of the clutch C1 and the increase of the engagement pressure of the forward / reverse switching mechanism 30 can be more appropriately executed, and the output from the engine 12 can be more appropriately limited.

  In addition, until now, when the above-mentioned car 10 is running with the D range selected as the shift range, the driver has switched to the D range after the shift range has been switched to the N range. As an example, the operation of the power transmission device 20 of the embodiment has been described. However, when the vehicle 10 is traveling in the D range selection state, the shift range is switched to D range-N range-R range. When the shift range is switched to R range-N range-R range while the vehicle 10 is traveling in the R range selected state, the vehicle 10 is traveling in the R range selected state. When the shift range is switched to R range-N range-D range, etc., processing similar to the processing described with reference to FIGS. And it may be line. The S range that can be selected in the shift unit can be handled in the same manner as the D range.

  Here, the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. That is, in the above embodiment, the primary pulley 43 provided on the primary shaft 42, the secondary pulley 45 provided on the secondary shaft 44, the belt 46 spanned between the primary pulley 43 and the secondary pulley 45, and the primary pulley 43 A CVT 40 having a primary cylinder 47 that can change the groove width of the secondary pulley 45 and a secondary cylinder 48 that can change the groove width of the secondary pulley 45 corresponds to a “continuously variable transmission”, and is driven by the engine 12 mounted on the automobile 10. The oil pump 24 capable of sucking and discharging the hydraulic oil from the oil pan 29 corresponds to a “pump”, and is mounted on the automobile 10 when the hydraulic oil is supplied from the oil pump 24 side and engaged. Power is transmitted from the engine 12 to the primary shaft 42 of the CVT 40 The clutch C1 and the brake B1 of the forward / reverse switching mechanism 30 to be capable of functioning correspond to a “fluid pressure clutch”, a linear solenoid valve SLT capable of regulating and outputting hydraulic oil corresponds to a “solenoid valve”, and a belt 46 of the CVT 40 Belt pressure control capable of adjusting the hydraulic oil from the oil pump 24 (primary regulator valve 51) side using hydraulic oil from the linear solenoid valve SLT to output to the secondary cylinder 48 of the CVT 40 in order to adjust the clamping pressure of the CVT 40 The valve 55 corresponds to a “nip pressure control valve”, and the working fluid from the oil pump 24 is regulated by using the working oil from the linear solenoid valve SLT to the primary cylinder 47, the secondary cylinder 48, the clutch C1, the brake B1, and the like. Primary regulator that generates the original pressure of the supplied hydraulic fluid The valve 51 corresponds to a “first pressure regulating valve”, and hydraulic oil from the linear solenoid valve SLT is used to regulate hydraulic oil from the oil pump 24 (line pressure regulating valve 52) side so that the clutch C1 and the brake B1. The clutch pressure control valve 58 that can output to the side corresponds to the “second pressure regulating valve”, and hydraulic oil can be supplied from the primary regulator valve 51 side (line pressure adjustment valve 52) to the clutch C1 or brake B1 side. The switching valve 57 that can set the state to be set and the state in which hydraulic oil can be supplied from the clutch pressure control valve 58 to the clutch C1 or the brake B1 side corresponds to the “switching valve”. The shifting ECU 21 that executes the switching control routine corresponds to a “control unit”. The “first pressure regulating valve” may be a line pressure regulating valve 52 that can regulate hydraulic oil from the oil pump 24 (primary regulator valve 51) side and output it to the clutch C1 or the brake B1 side. Good. However, the correspondence between the main elements of these embodiments and modifications and the main elements of the invention described in the column of means for solving the problem is described in the column of means for the embodiment to solve the problem. This is an example for specifically describing the best mode for carrying out the invention, and does not limit the elements of the invention described in the column of means for solving the problem. In other words, the examples are merely specific examples of the invention described in the column of means for solving the problem, and the interpretation of the invention described in the column of means for solving the problem is described in the description of that column. Should be done on the basis.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  The present invention can be used in the power transmission device manufacturing industry.

  10 automobiles, 12 engines, 14 electronic control units for engines (engine ECUs), 16 electronic control units for brakes (brake ECUs), 20 power transmission devices, 21 electronic control units for transmissions (transmission ECUs), 22 cases, 23 torques Converter, 23a Pump impeller, 23b Turbine runner, 24 Oil pump, 25 Pump assembly, 25a Pump body, 25b Pump cover, 27 External gear, 28 Strainer, 29 Oil pan, 30 Forward / reverse switching mechanism, 31 Planetary gear mechanism, 40 Continuously variable transmission (CVT), 41 Input shaft, 42 Primary shaft, 43 Primary pulley, 44 Secondary shaft, 45 Secondary pulley, 46 Belt, 47 Primary cylinder, 48 Secondary serial 50, hydraulic control unit, 51 primary regulator valve, 52 line pressure adjustment valve, 53 first shift control valve, 54 second shift control valve, 55 belt clamping pressure control valve, 56 manual valve, 57 switching valve, 58 clutch pressure Control valve, 80 gear mechanism, 82 differential gear, 84 axle, 91 accelerator pedal, 92 accelerator pedal position sensor, 93 brake pedal, 94 master cylinder pressure sensor, 95 shift lever, 96 shift range sensor, 99 vehicle speed sensor, B1 brake, C1 Clutch, DS1, DS2, DSC Duty solenoid valve, SL solenoid valve.

Claims (6)

A first pulley provided on the drive-side rotary shaft, a second pulley provided on the driven-side rotary shaft, a belt spanned between the first and second pulleys, and the first pulley A continuously variable transmission having a first fluid pressure cylinder capable of changing the groove width and a second fluid pressure cylinder capable of changing the groove width of the second pulley, and a power generation source mounted on the vehicle. A pump that is driven and capable of sucking and discharging the working fluid from the working fluid reservoir, and a drive side of the continuously variable transmission from the power generation source when engaged by receiving the supply of the working fluid from the pump side A power transmission device having a fluid pressure clutch capable of transmitting power to a rotating shaft,
A solenoid valve capable of regulating and outputting the working fluid;
In order to adjust the clamping pressure of the belt of the continuously variable transmission, the working fluid from the pump side is regulated using the working fluid from the solenoid valve to adjust the first and second of the continuously variable transmission. A clamping pressure control valve capable of outputting to one of the fluid pressure cylinders;
A first pressure regulator that regulates the working fluid from the pump using the working fluid from the solenoid valve to generate the original pressure of the working fluid supplied to the first and second cylinders and the fluid pressure clutch. A valve,
A second pressure regulating valve capable of regulating the working fluid from the pump side using the working fluid from the solenoid valve and outputting it to the fluid pressure clutch side;
A first communication state in which working fluid can be supplied from the first pressure regulating valve to the fluid pressure clutch, and a second communication state in which working fluid can be supplied from the second pressure regulating valve to the fluid pressure clutch. A switching valve capable of setting the communication state;
When the shift range is switched from the neutral range to the travel shift range, the switching valve is controlled to set the second communication state, and the working fluid is supplied from the second pressure regulating valve. The target pressure of the working fluid output from the second pressure regulating valve so that the pressure of the working fluid supplied from the second pressure regulating valve to the fluid pressure clutch is increased while the fluid pressure clutch is engaged. Is set within a range of an upper limit value based on an upper limit clamping pressure allowed for the belt of the continuously variable transmission, the solenoid valve is controlled based on the target pressure, and the target pressure is set to the upper limit value or a predetermined value. Control means for controlling the switching valve so as to set the first communication state when the pressure is reached;
A power transmission device comprising: The power transmission device according to claim 1,
When the shift range is switched from the neutral range to the travel shift range while the vehicle is traveling with the travel shift range selected, the control means A power transmission device that controls the switching valve so as to set a communication state. In the power transmission device according to claim 1 or 2,
The control means requests the power generation source to limit the output until the fluid pressure clutch is engaged after the accelerator pedal is depressed in a state where the second communication state is set by the switching valve. Power transmission device. In the power transmission device according to any one of claims 1 to 3,
The power transmission device in which the upper limit value based on the upper limit clamping pressure is set to be smaller as the gear ratio of the continuously variable transmission is smaller. In the power transmission device according to any one of claims 1 to 4,
The control means controls the switching valve so as to set the second communication state in accordance with switching from the neutral range to the travel range, and then inputs the input shaft of the fluid pressure clutch and the continuously variable transmission. The target pressure is set so that there is no difference in rotational speed with the drive side rotational shaft of the hydraulic pressure clutch, and the rotational speed of the input shaft of the fluid pressure clutch substantially coincides with the rotational speed of the drive side rotational shaft of the continuously variable transmission. In this state, the target pressure is set so that the pressure of the working fluid output from the second pressure regulating valve gradually increases, and the accelerator pedal is operated in the state where the second communication state is set by the switching valve. A power transmission device that requests the power generation source to limit the output until the rotation speed of the input shaft of the fluid pressure clutch and the rotation speed of the drive-side rotation shaft substantially coincide with each other after being depressed. In the power transmission device according to any one of claims 1 to 5,
The traveling range includes a forward traveling range and a backward traveling range,
The power transmission device, wherein the fluid pressure clutch is a forward clutch and a reverse clutch included in a forward / reverse switching mechanism disposed between the power generation source and the continuously variable transmission.

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