JP5317824B2 - Control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission mounted on a vehicle such as an automobile.

  A continuously variable transmission (CVT) mounted on a vehicle such as an automobile is provided with a primary pulley provided on the input shaft side and a secondary pulley provided on the output shaft side, and a drive belt that transmits power to each pulley ( A power transmission element) is wound around. The drive belt is sandwiched between a fixed sheave and a movable sheave that form each pulley. For example, when the hydraulic oil is supplied to and discharged from a primary pulley (transmission pulley), the movable sheave approaches or moves away from the fixed sheave. The winding diameter of the drive belt changes, and the gear ratio is controlled steplessly. In addition, by supplying and discharging hydraulic oil to and from the secondary pulley (clamping pulley), the movable sheave moves closer to or away from the fixed sheave, and the drive belt clamping force (clamping force) changes, suppressing slippage of the drive belt. Power transmission efficiency is improved.

  The gear ratio control of the continuously variable transmission is performed by a controller mounted on the vehicle, and the controller sets a target gear ratio based on the throttle opening and the vehicle speed with reference to a control map. The controller supplies hydraulic oil (primary pressure) having a predetermined pressure for obtaining the set target speed ratio to the primary pulley, and thereby the speed ratio is controlled to the target speed ratio.

  As a control device for controlling such a continuously variable transmission, for example, a technique described in Patent Document 1 is known. The control device for a continuously variable transmission described in Patent Document 1 includes a primary control valve and a secondary control valve between a primary pulley and an oil pump (operating oil supply source). The primary control valve is arranged on the primary pulley side, and hydraulic oil is supplied to and discharged from the primary pulley to regulate the primary pressure. The secondary control valve is arranged on the oil pump side, and the secondary pulley has a predetermined pressure of hydraulic oil (secondary pressure). Or the secondary pressure is supplied to the primary control valve.

  The control device for a continuously variable transmission described in Patent Document 1 provides a fail-safe measure in which the gear ratio is an intermediate gear ratio when the primary control valve fails for some reason (such as a power fault or a disconnection fault). ing. As a result, the gear ratio is suddenly downshifted at high speeds, causing wheel locks, etc., and suppressing the behavioral instability of the vehicle. Further, the gear ratio is fixed on the high speed side (small gear ratio), This makes it difficult for the vehicle to restart / re-accelerate.

  In the control device for a continuously variable transmission described in Patent Document 1, hydraulic oil is supplied to and discharged from the primary pulley by one primary control valve. For example, two controls are performed for one primary pulley. Control of a continuously variable transmission that is connected to a valve (supply valve / discharge valve), controls supply of hydraulic oil to the primary pulley by the supply valve, and controls discharge of hydraulic oil from the primary pulley by the discharge valve Devices have also been proposed.

  In such a continuously variable transmission control device having two control valves, a hydraulic circuit of a supply system and a hydraulic circuit of a discharge system can be provided separately. For example, the residual pressure of the hydraulic circuit of the supply system is discharged. Does not affect the hydraulic circuit of the system. Therefore, there is an advantage that the response of switching between the supply control and the discharge control of the hydraulic oil to the primary pulley can be improved, and more accurate gear ratio control can be realized.

Japanese Patent Laid-Open No. 5-106728 (FIG. 1)

  However, the control device for a continuously variable transmission described in Patent Document 1 uses a gear ratio as an intermediate gear ratio when the primary control valve fails. For example, the primary control valve fails at a higher gear ratio. Even in this case, a downshift to an intermediate gear ratio is allowed. Therefore, downshifting when traveling at a higher speed may cause anxiety to the driver, so it is desirable not to cause a downshift if the primary control valve fails during high speed traveling. Moreover, it is desirable to improve the responsiveness of the fail-safe control that prevents downshifting. By applying the control to the continuously variable transmission having the two control valves as described above, the operation is further improved. It becomes possible to realize a control device for a continuously variable transmission that does not give a person anxiety.

  An object of the present invention is a control device for a continuously variable transmission that upshifts / downshifts by a supply valve / discharge valve, and can reliably prevent a downshift even if a discharge solenoid fails during high-speed driving. An object of the present invention is to provide a control device for a step transmission.

A control device for a continuously variable transmission according to the present invention includes a transmission pulley and a tightening pulley around which a power transmission element is wound, and adjusts supply / discharge of hydraulic oil to and from the transmission pulley to control a winding diameter of the power transmission element A control device for a continuously variable transmission that adjusts supply and discharge of hydraulic oil to and from the clamping pulley to control a clamping force with respect to the power transmission element, the hydraulic oil being supplied to the transmission pulley and the clamping pulley; A hydraulic oil supply source for supplying the hydraulic oil; an oil pan for storing the hydraulic oil; and a communication state and a supply for supplying the hydraulic oil to the transmission pulley, provided between the hydraulic oil supply source and the transmission pulley. A supply valve that is switched to a shut-off state that stops, and a communication state that is provided between the speed change pulley and the oil pan and that discharges the hydraulic oil from the speed change pulley, and a shut-off state that stops discharge. A second discharge valve that is provided between the first discharge valve and the oil pan, and is switched between a communication state for discharging the hydraulic oil from the first discharge valve and a cutoff state for stopping the discharge. A supply solenoid having a discharge valve, a supply position in which the supply valve is in a communication state and the second discharge valve is in a shut-off state, and a discharge position in which the supply valve is in a cut-off state and the second discharge valve is in a communication state; A discharge solenoid having a communication position for bringing the first discharge valve into a communication state, a shut-off position for shutting off the first discharge valve, a controller for controlling the supply solenoid and the discharge solenoid, and the controller. receives a failure signal from the exhaust solenoid, a failure detecting means for detecting a fault condition of the discharge solenoid, detects the vehicle speed of the vehicle, the controller And a vehicle speed detecting means for outputting a vehicle speed signal, when the controller having detected the fault signal, switches the discharge solenoid shut-off position, when the vehicle speed signal is above a predetermined value, the supply position of the supply solenoid When the vehicle speed signal is less than a predetermined value, the supply solenoid is switched to the discharge position.

  In the continuously variable transmission control device according to the present invention, the controller sets the discharge position of the supply solenoid even when the vehicle speed signal becomes a predetermined value or more after the supply solenoid is switched to the discharge position. It is characterized by holding.

According to the present invention, a supply valve that supplies hydraulic oil to the transmission pulley, a first discharge valve that discharges hydraulic oil from the transmission pulley, a second discharge valve that discharges hydraulic oil from the first discharge valve, and a supply valve A supply solenoid having a supply position where the second discharge valve is in communication and a supply position where the supply valve is closed and a discharge position where the second discharge valve is in communication; and a communication position where the first discharge valve is in communication And a discharge solenoid having a blocking position for blocking the first discharge valve. When the controller detects a failure signal of the discharge solenoid, the controller switches the discharge solenoid to the shut-off position, switches the supply solenoid to the supply position when the vehicle speed signal is equal to or higher than a predetermined value, and sets the supply solenoid to the discharge position when the vehicle speed signal is lower than the predetermined value. Switch. Therefore, when the discharge solenoid fails at the communication position or the cutoff position and the gear ratio is on the high speed side, the downshift can be prevented by setting the supply valve to the communication state and the second discharge valve to the cutoff state. This prevents downshifting when the gear ratio is on the high speed side, so that the driver does not feel uneasy. Further, when the discharge solenoid breaks down at the communication position or the shut-off position and the gear ratio is on the low speed side, it is possible to prevent the upshift by setting the supply valve in the shut-off state and the second discharge valve in the communication state.

  According to the present invention, the controller maintains the discharge position of the supply solenoid even when the vehicle speed signal becomes a predetermined value or higher after switching the supply solenoid to the discharge position. It is possible to secure a minimum vehicle running performance by fixing.

It is a skeleton figure of a continuously variable transmission. 1 is a hydraulic circuit diagram of a control device for a continuously variable transmission according to the present invention. It is a main flowchart explaining the content of gear ratio control. It is explanatory drawing explaining operation | movement of the control apparatus at the time of making a gear ratio small. It is explanatory drawing explaining operation | movement of the control apparatus at the time of enlarging a gear ratio. (A), (b) is the table | surface which summarized the problem at the time of failure of a discharge solenoid, and the table | surface which summarized the content of the fail safe control which concerns on this invention. It is a sub-flowchart explaining the failure determination processing content of a discharge solenoid. It is explanatory drawing explaining the fail safe operation | movement at the time of the discharge solenoid having an OPEN failure. It is explanatory drawing explaining the fail safe operation | movement at the time of a discharge solenoid having a CLOSE failure.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a skeleton diagram of a continuously variable transmission, and FIG. 2 is a hydraulic circuit diagram of a control device for a continuously variable transmission according to the present invention.

  As shown in FIG. 1, the continuously variable transmission 10 is mounted on a vehicle (not shown) such as an automobile, and is provided in parallel with the primary shaft 12 and a primary shaft (input shaft) 12 driven by the engine 11. A secondary shaft (output shaft) 13 is provided. A transmission mechanism 14 is provided between the primary shaft 12 and the secondary shaft 13, and the rotation of the primary shaft 12 is transmitted to the secondary shaft 13 via the transmission mechanism 14, and the rotation of the secondary shaft 13 is reduced by the speed reduction mechanism 15 and the differential mechanism. 16 to the left and right drive wheels 17.

  A primary pulley (transmission pulley) 20 is provided on the primary shaft 12. The primary pulley 20 includes a fixed sheave 20a provided on the primary shaft 12 so as to be integrally rotatable, and a movable sheave 20b that is opposed to the fixed sheave 20a and slides in the axial direction with respect to the primary shaft 12. A secondary pulley (clamping pulley) 21 is provided on the secondary shaft 13. The secondary pulley 21 includes a fixed sheave 21a provided on the secondary shaft 13 so as to be integrally rotatable, and a movable sheave 21b that faces the fixed sheave 21a and slides in the axial direction with respect to the secondary shaft 13.

  A driving belt (power transmission element) 22 is wound around the primary pulley 20 and the secondary pulley 21. Then, by moving the movable sheaves 20b and 21b close to or away from the fixed sheaves 20a and 21a, the groove widths of the primary pulley 20 and the secondary pulley 21 are changed, and the winding diameter of the drive belt 22 is steplessly changed. It is possible to change (change the gear ratio steplessly). Here, when the winding diameter of the drive belt 22 around the primary pulley 20 is Rp and the winding diameter around the secondary pulley 21 is Rs, the transmission ratio of the transmission mechanism 14 is Rs / Rp.

  The primary pulley 20 includes a plunger 23 fixed to the primary shaft 12 and a cylinder 24 fixed to the movable sheave 20b. The inner peripheral surface of the cylinder 24 is in sliding contact with the outer peripheral surface of the plunger 23, and the plunger 23 and the cylinder 24 define a hydraulic oil chamber 25 through which hydraulic oil enters and exits. The secondary pulley 21 includes a plunger 26 fixed to the secondary shaft 13 and a cylinder 27 fixed to the movable sheave 21b. The inner peripheral surface of the cylinder 27 is in sliding contact with the outer peripheral surface of the plunger 26, and the plunger 26 and the cylinder 27 define a hydraulic oil chamber 28 through which hydraulic oil enters and exits. The groove widths of the pulleys 20 and 21 are controlled by adjusting the primary pressure Pp supplied to the primary hydraulic fluid chamber 25 and the secondary pressure Ps supplied to the secondary hydraulic fluid chamber 28, respectively. .

  Between the crankshaft 11a of the engine 11 and the primary shaft 12, a torque converter 30 and a forward / reverse switching mechanism 31 are provided. The torque converter 30 includes a pump impeller 30a connected to the crankshaft 11a and a turbine runner 30b facing the pump impeller 30a. A turbine shaft 32 is connected to the turbine runner 30b. A lock-up clutch 33 that fastens the crankshaft 11a and the turbine shaft 32 according to the traveling state of the vehicle is provided in the torque converter 30.

  The forward / reverse switching mechanism 31 includes a double-pinion planetary gear train 34, a forward clutch 35, and a reverse brake 36. The forward clutch 35 and the reverse brake 36 are operated to switch the power transmission path of the engine 11. I am doing so. When both the forward clutch 35 and the reverse brake 36 are released, the turbine shaft 32 and the primary shaft 12 are disconnected, and the forward / reverse switching mechanism 31 is switched to a neutral state in which power is not transmitted to the primary shaft 12. When the reverse brake 36 is released and the forward clutch 35 is engaged, the rotation of the turbine shaft 32 is transmitted to the primary pulley 20 as it is. When the forward clutch 35 is released and the reverse brake 36 is engaged, the reverse rotation is reversed. The rotation of the turbine shaft 32 is transmitted to the primary pulley 20.

  As shown in FIG. 2, the control device 40 that performs gear ratio control of the continuously variable transmission 10 supplies and discharges hydraulic oil to and from the hydraulic oil chambers 25 and 28 that form the primary pulley 20 and the secondary pulley 21. It is formed by the hydraulic circuit to perform.

  An oil pump (hydraulic oil supply source) 41 driven by the engine 11 (see FIG. 1) is provided on one side (left side in the figure) of the control device 40. The oil pump 41 supplies hydraulic oil to the primary pulley 20 and the secondary pulley 21 provided on the other side (right side in the drawing) of the control device 40.

  An oil pan 42 that stores hydraulic oil is provided on the upstream side of the oil pump 41, and the hydraulic oil stored in the oil pan 42 is sucked from a suction port of the oil pump 41 through a strainer (filter) 43. One end side of the first line conduit 44 and the second line conduit 45 is connected to the downstream side of the oil pump 41, and the other end side of the first line conduit 44 is connected to the hydraulic oil chamber 28 of the secondary pulley 21. Has been.

  A line pressure control valve 50 is provided in the middle of the first line conduit 44. The line pressure control valve 50 is controlled by the CVT control unit 90 and opens part of the hydraulic oil from the oil pump 41 to the downstream side so as to generate a line pressure PL that becomes the reference hydraulic pressure of the hydraulic circuit. . A part of the hydraulic fluid opened by the line pressure control valve 50 is sent to each hydraulic operating device (not shown) via a lubrication circuit 51 provided on the downstream side of the line pressure control valve 50, and further, a pilot. The pressure PP is sent to the supply solenoid 52 and the discharge solenoid 53 via the lubrication line 46. The surplus hydraulic fluid sent from the lubrication circuit 51 is returned to the oil pan 42.

  A supply valve 60 for supplying hydraulic oil to the hydraulic oil chamber 25 of the primary pulley 20 is connected to the other end side of the second line conduit 45. The supply valve 60 is provided between the oil pump 41 and the primary pulley 20 and is a normally closed (normally closed) pilot-controlled spool valve. The supply valve 60 includes a casing 61 and a spool 62 that slides in the casing 61, and the casing 61 is connected to the inflow port 61 a to which the second line pipe 45 is connected and to the exhaust pipe to which one end side of the primary pipe 47 is connected. A pilot port 61c to which the other end side of the port 61b and the first pilot pipe line 48a is connected is formed. Here, the other end side of the primary pipeline 47 is connected to the hydraulic oil chamber 25 of the primary pulley 20, and one end side of the first pilot pipeline 48 a is connected to the supply solenoid 52.

  The spool 62 includes an open / close land (valve portion) 62a that switches the inflow port 61a and the discharge port 61b to a communication state or a cutoff state. The supply valve 60 is connected by the open / close land 62a by switching the supply solenoid 52 to the supply position, supplies hydraulic oil to the primary pulley 20, and shuts off by the open / close land 62a by switching the supply solenoid 52 to the discharge position. The supply of hydraulic oil to the primary pulley 20 is stopped.

  A spring 63 that moves the spool 62 to shut off the inflow port 61a and the discharge port 61b is provided on one end side of the open / close land 62a. A pressure receiving land 62b that receives the pilot pressure PP from the pilot port 61c is provided on the other end side of the open / close land 62a. As a result, the spool 62 moves due to the balance between the pilot pressure PP from the pilot port 61 c and the biasing force of the spring 63. A plurality of concave grooves 62c extending in the longitudinal direction are formed on the outer periphery of the open / close land 62a, and each concave groove 62c serves to suppress a sudden increase in the pressure of the primary conduit 47 due to the movement of the spool 62. To fulfill.

  A discharge valve (first discharge valve) 70 for discharging hydraulic oil from the hydraulic oil chamber 25 of the primary pulley 20 is connected to the middle of the primary pipeline 47. The discharge valve 70 is provided between the primary pulley 20 and the oil pan 42 and is a normally closed pilot-controlled spool valve similar to the supply valve 60. The discharge valve 70 includes a casing 71 and a spool 72 that slides in the casing 71. The casing 71 has an inflow port 71 a to which the primary pipe 47 is connected and a discharge port to which the other end of the discharge pipe 49 is connected. A pilot port 71c to which the other end of the third pilot pipe line 48c is connected is formed. Here, one end side of the discharge pipe line 49 is connected to the inflow port 81 a of the discharge switch valve 80, and one end side of the third pilot pipe line 48 c is connected to the discharge solenoid 53.

  The spool 72 includes an open / close land 72a that switches the inflow port 71a and the discharge port 71b to a communication state or a cutoff state. The discharge valve 70 is connected to the open / close land 72a by switching the discharge solenoid 53 to the communication position, discharges the hydraulic oil from the primary pulley 20, and is cut off by the open / close land 72a by switching the discharge solenoid 53 to the cut-off position. The discharge of hydraulic oil from the primary pulley 20 is stopped.

  On one end side of the open / close land 72a, a spring 73 is provided that moves the spool 72 to shut off the inflow port 71a and the discharge port 71b. A pressure receiving land 72b that receives the pilot pressure PP from the pilot port 71c is provided on the other end side of the open / close land 72a. As a result, the spool 72 moves due to the balance between the pilot pressure PP from the pilot port 71 c and the biasing force of the spring 73.

  The discharge switch valve 80 is provided between the discharge valve 70 and the oil pan 42. The discharge switch valve 80 is a normally open (normally open) pilot-controlled spool valve, and includes a casing 81 and a spool 82 that slides inside the casing 81. The casing 81 is formed with an inflow port 81a to which one end of the discharge pipe 49 is connected, a drain port 81b for returning hydraulic oil to the oil pan 42, and a pilot port 81c to which the other end of the second pilot pipe 48b is connected. ing. Here, one end side of the second pilot pipeline 48 b is connected to the supply solenoid 52.

  The spool 82 includes an open / close land 82a that switches the inflow port 81a and the drain port 81b to a communication state or a cutoff state. The discharge switch valve 80 is connected to the open / close land 82a by switching the supply solenoid 52 to the discharge position, discharges hydraulic fluid from the discharge valve 70, and switches the supply solenoid 52 to the supply position to switch the supply solenoid 52 to the discharge position. The shut-off state is set, and the discharge of hydraulic oil from the discharge valve 70 is stopped.

  A spring seat land 82b is provided on the other end side of the open / close land 82a, and a spring 83 that moves the spool 82 to bring the inflow port 81a and the drain port 81b into communication with each other on the other end side of the spring seat land 82b. Is provided. The pilot pressure PP from the pilot port 81c acts on one end side of the open / close land 82a, so that the spool 82 balances the pilot pressure PP from the pilot port 81c and the urging force of the spring 83. To move.

  As shown in FIG. 2, the control device 40 includes a CVT control unit (controller) 90 installed in a glove box or the like (not shown) in the vehicle interior. A line pressure control valve 50, a supply solenoid 52, and a discharge solenoid 53 are electrically connected to the CVT control unit 90, respectively. The CVT control unit 90 connects the line pressure control valve 50, the supply solenoid 52, and the discharge solenoid 53 to a predetermined range. Opening and closing control is performed based on the control logic.

  The CVT control unit 90 is electrically connected to an engine control unit 91, a throttle opening sensor 92, a vehicle speed sensor 93, a primary rotational speed sensor 94, and a secondary rotational speed sensor 95 via an interface (not shown). The CVT control unit 90 refers to a control map (not shown) based on vehicle information signals from the engine control unit 91, the throttle opening sensor 92, the vehicle speed sensor 93, the primary rotational speed sensor 94, and the secondary rotational speed sensor 95. Thus, the target speed ratio is set, and the primary pressure Pp and the secondary pressure Ps based on the target speed ratio are calculated.

  The CVT control unit 90 further includes a failure determination unit 96 that determines a failure of the discharge solenoid 53. The failure determination unit 96 receives a failure signal output from the discharge solenoid 53 and detects a failure state of the discharge solenoid 53 based on the input of the failure signal. The CVT control unit 90 performs fail-safe control of the control device 40 based on a predetermined control logic when the failure determination unit 96 determines that the discharge solenoid 53 has failed.

  Next, operation | movement of the control apparatus 40 formed as mentioned above is demonstrated in detail using drawing.

  FIG. 3 is a main flowchart for explaining the contents of the gear ratio control, FIG. 4 is an explanatory diagram for explaining the operation of the control device when the gear ratio is reduced, and FIG. 5 is the operation of the control device when the gear ratio is increased. Explanatory drawing explaining each is represented.

  As shown in FIG. 3, a gear ratio control program is started by turning on an ignition switch (not shown) (step S1). In step S 2, the current vehicle information signal is input to the CVT control unit 90 from the engine control unit 91, the throttle opening sensor 92, the vehicle speed sensor 93, and the like. In step S3, the CVT control unit 90 refers to the control map based on the input various vehicle information signals, and sets the target gear ratio from the control map. Then, the optimal primary pressure Pp and secondary pressure Ps are calculated based on the set target gear ratio. In step S4, the line pressure control valve is set so that the pressure in the hydraulic oil chamber 25 of the primary pulley 20 becomes the primary pressure Pp, and the pressure in the hydraulic oil chamber 28 of the secondary pulley 21 becomes the secondary pressure Ps. 50, the supply solenoid 52 and the discharge solenoid 53 are each opened and closed. Each of the line pressure control valve 50, the supply solenoid 52, and the discharge solenoid 53 has a movable body (not shown). For example, the movable body is vibrated by duty control to thereby fix the movable body. The smooth movement of the movable body and the positional accuracy are improved.

  In step S <b> 5, failure determination processing for the discharge solenoid 53 is executed by the failure determination unit 96 of the CVT control unit 90. If the discharge solenoid 53 is normal, a return process is performed in step S6, the process returns to step S2, and various vehicle information signals are input to the CVT control unit 90 again. When the discharge solenoid 53 is out of order, fail-safe control (see FIG. 7) described later is executed.

  Here, a specific operation of the control device 40 when the gear ratio is changed to the high speed side and when it is changed to the low speed side will be described.

[Speed ratio control to high speed]
In order to change the gear ratio to the high speed side so that the vehicle can travel at high speed, first, the line pressure control valve 50 is opened at a predetermined opening degree, and the first line pipe 44 as shown in FIG. And the 2nd line conduit 45 becomes predetermined line pressure PL. Further, the lubrication pipeline 46 becomes a pilot pressure PP (PP <PL) having a pressure smaller than the line pressure PL via the lubrication circuit 51. The supply solenoid 52 is opened to the supply position (OPEN), and the discharge solenoid 53 is closed to the cutoff position (CLOSE).

  As the supply solenoid 52 is switched to the supply position, the first pilot pipe line 48a and the second pilot pipe line 48b become the pilot pressure PP. The hydraulic oil having the pilot pressure PP flows into the casing 61 of the supply valve 60 through the pilot port 61c, and the pressure receiving land 62b of the spool 62 receives the pilot pressure PP. Due to the pilot pressure PP, the spool 62 moves by pushing and contracting the spring 63 as shown by an arrow (1a) in the figure, whereby the open / close land 62a connects the inflow port 61a and the discharge port 61b, and the supply valve 60 is in communication. Thus, the second line 45 and the primary line 47 communicate with each other.

  The hydraulic oil of the pilot pressure PP flows into the casing 81 of the discharge switch valve 80 through the pilot port 81c, and the open / close land 82a of the spool 82 receives the pilot pressure PP. Due to the pilot pressure PP, the spool 82 moves by pushing and contracting the spring 83 as shown by an arrow (2a) in the figure, whereby the open / close land 82a shuts off the inflow port 81a and the drain port 81b, and the discharge switch valve 80 shuts off. As a result, the discharge pipe 49 and the oil pan 42 are shut off.

  Since the discharge solenoid 53 is in the blocking position, the lubrication pipeline 46 and the third pilot pipeline 48c are blocked. Accordingly, the pilot pressure PP does not act on the discharge valve 70, and the spool 72 is in the cut-off state due to the biasing force of the spring 73, and the discharge valve 70 maintains the cut-off state between the primary pipe line 47 and the discharge pipe line 49.

  As a result, the pressure in the hydraulic oil chamber 25 of the primary pulley 20 is increased to the primary pressure Pp, and the movable sheave 20b moves close to the fixed sheave 20a as indicated by an arrow (3a) in the figure. Therefore, as shown by the arrow (4a) in the figure, the drive belt 22 moves outward in the radial direction of the primary pulley 20, and the winding diameter Rp of the drive belt 22 increases.

  On the other hand, the pressure in the hydraulic oil chamber 28 of the secondary pulley 21 is increased to the secondary pressure Ps substantially equal to the line pressure PL. At this time, the movable sheave 21b moves away from the fixed sheave 21a as shown by an arrow (5a) in the figure as the winding diameter Rp of the drive belt 22 with respect to the primary pulley 20 is increased. Then, the winding diameter Rs of the drive belt 22 with respect to the secondary pulley 21 is reduced, and the transmission gear ratio is reduced (upshift). In addition, the movable sheave 21b applies a clamping force CF in the direction of the broken arrow in the figure due to the increased secondary pressure Ps to the drive belt 22, thereby suppressing the slip of the drive belt 22.

[Speed ratio control to low speed]
In order to change the gear ratio to the low speed side so that the vehicle can travel at a low speed, first, the line pressure control valve 50 is opened at a predetermined opening, and the first line pipe 44 as shown in FIG. And the 2nd line conduit 45 becomes predetermined line pressure PL. Further, the lubrication pipeline 46 becomes a pilot pressure PP (PP <PL) having a pressure smaller than the line pressure PL via the lubrication circuit 51. The supply solenoid 52 is closed to the discharge position (CLOSE), and the discharge solenoid 53 is opened to the communication position (OPEN).

  Since the supply solenoid 52 is in the discharge position, the lubrication pipeline 46, the first pilot pipeline 48a, and the second pilot pipeline 48b are blocked, and the pilot pressure PP does not act on the supply valve 60 and the exhaust switch valve 80. Accordingly, the spool 62 of the supply valve 60 is pressed by the urging force of the spring 63 as shown by the arrow (1b) in the drawing, and the inflow port 61a and the discharge port 61b are blocked by the open / close land 62a. Accordingly, the supply valve 60 is cut off, and the second line conduit 45 and the primary conduit 47 are shut off.

  Further, the spool 82 of the discharge switch valve 80 is pressed by the urging force of the spring 83 as shown by an arrow (2b) in the figure, and the open / close land 82a communicates the inflow port 81a and the drain port 81b. Therefore, the discharge switch valve 80 is in communication, and the discharge pipe 49 and the oil pan 42 are in communication.

  As the discharge solenoid 53 is switched to the communication position, the third pilot line 48c becomes the pilot pressure PP. The hydraulic oil having the pilot pressure PP flows into the casing 71 of the discharge valve 70 via the pilot port 71c, and the pressure receiving land 72b of the spool 72 receives the pilot pressure PP. Due to the pilot pressure PP, the spool 72 moves by pushing and contracting the spring 73 as shown by an arrow (3b) in the figure, whereby the open / close land 72a communicates the inflow port 71a and the exhaust port 71b, and the exhaust valve 70 is in communication. Thus, the primary conduit 47 and the discharge conduit 49 communicate with each other.

  As a result, the hydraulic oil in the hydraulic oil chamber 25 of the primary pulley 20 is returned to the oil pan 42 via the primary conduit 47 and the discharge conduit 49, and the primary pressure Pp decreases. On the other hand, the pressure in the hydraulic oil chamber 28 of the secondary pulley 21 is increased to the secondary pressure Ps substantially equal to the line pressure PL.

  Accordingly, the movable sheave 20b of the primary pulley 20 moves away from the fixed sheave 20a as indicated by an arrow (4b) in the figure, and accordingly, as indicated by an arrow (5b) in the figure, the drive belt 22 for the primary pulley 20 is driven. The winding diameter Rp is reduced. Further, the movable sheave 21b of the secondary pulley 21 moves close to the fixed sheave 21a as indicated by an arrow (6b) in the figure, and the winding diameter Rs of the drive belt 22 with respect to the secondary pulley 21 is increased to increase the gear ratio. (Downshift). In addition, the movable sheave 21b applies a clamping force CF in the direction of the broken arrow in the figure due to the increased secondary pressure Ps to the drive belt 22, thereby suppressing the slip of the drive belt 22.

  Next, the contents of the discharge solenoid failure determination process in step S5 of FIG. 3 will be described in detail with reference to the drawings.

  6A and 6B are a table summarizing problems at the time of failure of the discharge solenoid and a table summarizing the contents of the fail-safe control according to the present invention, and FIG. FIG. 8 is an explanatory diagram for explaining the fail-safe operation when the discharge solenoid has an OPEN failure, and FIG. 9 is an explanatory diagram for explaining the fail-safe operation when the discharge solenoid has a CLOSE failure. .

  Here, prior to describing the operation of fail-safe control, problems that may occur when the discharge solenoid 53 fails are described. As shown in FIG. 6A, for example, when the discharge solenoid 53 fails when the vehicle speed is high, the following problems may occur.

  If the discharge solenoid 53 is fixed in the valve open state due to a power fault (OPEN failure), the discharge valve 70 is in a communication state. As a result, the primary pressure Pp may decrease, causing a sudden downshift, or the secondary pressure Ps may decrease as the line pressure PL decreases. On the other hand, when the discharge solenoid 53 is broken and fixed in the closed state (CLOSE failure), the discharge valve 70 is cut off. As a result, the primary pressure Pp is maintained or increased, and the gear ratio is fixed with the gear ratio being small, or the gear ratio is less than that, and it may be difficult to re-accelerate after the vehicle speed decreases. Therefore, in the present invention, the fail safe control executed after detecting the failure of the discharge solenoid 53 is made different depending on the vehicle speed state, that is, the magnitude of the vehicle speed signal from the vehicle speed sensor 93.

  As shown in FIG. 7, when the failure determination process for the discharge solenoid 53 is executed in step S10, it is determined in the subsequent step S11 whether or not a failure signal from the discharge solenoid 53 is detected. If it is determined in step S11 that a failure signal is not detected (no), the discharge solenoid 53 is assumed to be normal, and the routine returns to step S2 (see FIG. 3) and normal control (normal control) is continued. If it is determined in step S11 that a failure signal has been detected (yes), the process proceeds to step S12, and a failure determination flag for the discharge solenoid 53 is set. Here, a warning light (not shown) on the meter panel may be turned on to inform the driver that the discharge solenoid 53 is broken, that is, the control device 40 (see FIG. 2) is broken.

  The processing content after step S13 indicates the processing content of fail-safe control. In step S13, it is determined whether or not the vehicle speed signal from the vehicle speed sensor 93 has not experienced less than Vakm / h as the first threshold value. Here, the threshold value Va is set to 10 km / h, for example. When it is determined in step S13 that the vehicle speed is less than Vakm / h (yes), the process proceeds to step S14.

  In step S14, it is determined whether or not the vehicle speed is equal to or higher than Vbkm / h as the second threshold value. Here, the threshold value Vb is set to 20 km / h, for example, which is larger than the threshold value Va (Vb> Va). If it is determined in step S14 that the vehicle speed is equal to or higher than Vbkm / h (yes), the process proceeds to step S15.

  In step S15, based on the fact that “the vehicle speed is less than Vakm / h” and “the vehicle speed is Vbkm / h or more”, it is assumed that the vehicle is traveling at high speed, and the supply solenoid 52 is turned on (OPEN) to supply the vehicle. Control to position. In step S15, in consideration of a problem caused by a decrease in the primary pressure Pp, a drive signal for turning the discharge solenoid 53 OFF (CLOSE) to set the cut-off position is sent to the discharge solenoid 53.

  As a result, as shown in FIG. 8, even when the discharge solenoid 53 is OPEN-failed and the discharge valve 70 is held in communication (when the spool 72 cannot move in the direction of the broken line arrow in the figure), The spool 62 of the valve 60 moves in the direction of the arrow (1c) in the figure, and the spool 82 of the discharge switch valve 80 moves in the direction of the arrow (2c) in the figure. Therefore, the primary pressure Pp is maintained or higher, and the current gear ratio is maintained or smaller, so that a sudden downshift is prevented and the driver is not anxious (FIG. 6). (See (b) Top). Since the line pressure PL is held, the clamping force CF against the drive belt 22 by the secondary pulley 21 is held.

  In a succeeding step S16, it is determined whether or not the vehicle speed is less than Vakm / h. If the driver continues the accelerator operation and determines that the vehicle speed is still equal to or higher than Vakm / h (no), the process returns to step S14. On the other hand, if it is determined (yes) that the vehicle speed is less than Vakm / h, for example, when the driver performs a brake operation, the process proceeds to step S17, assuming that the vehicle speed is less than Vakm / h.

  In step S17, based on the fact that the vehicle speed is less than Vakm / h, the supply solenoid 52 is turned off (CLOSE) to control the discharge position. In step S17, as in the process in step S15, a drive signal for turning the discharge solenoid 53 OFF (CLOSE) to set the shut-off position is sent to the discharge solenoid 53.

  As a result, as shown in FIG. 9, even if the discharge solenoid 53 is in a CLOSE failure and the discharge valve 70 is held in the shut-off state (when the spool 72 cannot move in the direction of the broken line arrow in the drawing) The spool 62 of the valve 60 moves in the direction of the arrow (1d) in the figure, and the spool 82 of the discharge switch valve 80 moves in the direction of the arrow (2d) in the figure. Therefore, it is possible to prevent the primary pressure Pp from becoming higher, prevent an upshift from the current gear ratio, and prepare for re-acceleration from a vehicle speed reduction state (see the middle stage in FIG. 6B). . Since the line pressure PL is held, the clamping force CF against the drive belt 22 by the secondary pulley 21 is held.

  In step S18, a return process is executed and the process returns to step S11. Thereafter, the processes after step S12 are performed again. In step S13 in the current control cycle, the determination in step S16 in the previous control cycle is “yes” (the vehicle speed is less than Vakm / h). That is, in step S13 in the control cycle after this time, it is determined that the vehicle speed has experienced less than Vakm / h. Therefore, once the supply solenoid 52 is switched to the discharge position, the discharge position of the supply solenoid 52 is maintained even when the vehicle speed is equal to or higher than Vakm / h. That is, without changing the vehicle speed, the gear ratio is fixed (fixed on the low speed side) in preparation for re-acceleration from the vehicle speed reduction state, thereby ensuring the minimum vehicle travelability (see the lower part of FIG. 6 (b)). reference).

  If the vehicle speed is initially less than Vakm / h in the first (previous) control cycle, the determination in step S13 is no (has experienced less than Vakm / h), and the process proceeds directly to step S17. Then, in the subsequent control cycle, the gear ratio is fixed on the low speed side, thereby ensuring the minimum vehicle travelability (see the lower part of FIG. 6B).

  Furthermore, when it is determined to be no in step S14, that is, when the vehicle speed is equal to or higher than Vakm / h and lower than Vbkm / h, the vehicle speed is assumed to be on the low speed side. Since there is almost no feeling, the process directly proceeds to step S17, and the gear ratio is fixed on the low speed side in the subsequent control cycle. This ensures the minimum vehicle travelability (see the lower part of FIG. 6B).

  Thus, after determining that the vehicle speed has experienced less than Vakm / h in step S13, the gear ratio is fixed on the low speed side in step S17. As a result, it is possible to clearly notify the driver that the vehicle has broken down as a result of being unable to travel at high speed, and further to be urged to be repaired. In this case, since the minimum vehicle travelability is ensured, it is possible to self-travel to a repair shop or the like by using a general road.

  If it is determined in step S11 that the discharge solenoid 53 has temporarily failed due to some cause (generation of noise or the like), failsafe control can be canceled in the subsequent determination in step S11. . In this case, the fail safe control is reset (initialized), and the control device 40 is returned to the normal gear ratio control.

  As described above in detail, according to the control device 40 according to the present embodiment, the supply valve 60 that supplies hydraulic oil to the primary pulley 20, the discharge valve 70 that discharges hydraulic oil from the primary pulley 20, and the discharge valve 70, a discharge switch valve 80 that discharges hydraulic fluid from 70, a supply position in which the supply valve 60 is in communication and the discharge switch valve 80 is in a disconnected state, and a discharge position in which the supply valve 60 is in a closed state and the discharge switch valve 80 is in communication And a discharge solenoid 53 having a communication position where the discharge valve 70 is in communication and a cutoff position where the discharge valve 70 is closed. The CVT control unit 90 detects the failure signal of the discharge solenoid 53 and switches the supply solenoid 52 to the supply position when the vehicle speed is equal to or higher than Vbkm / h. Therefore, when the gear ratio is on the high speed side, the supply valve 60 can be in the communication state and the discharge switch valve 80 can be in the shut-off state, preventing the downshift and not giving the driver anxiety.

  Further, according to the control device 40 according to the present embodiment, since the supply valve 60 and the discharge valve 70 are provided, the responsiveness of switching between the supply control and the discharge control of the hydraulic oil is improved, and more accurate. Gear ratio control can be realized. Since the responsiveness of switching between the supply control and the discharge control can be improved, the responsiveness of the failsafe control when the discharge solenoid 53 is faulty can be improved, and the failsafe is hardly caused to the driver. Control can be performed.

  Furthermore, according to the control device 40 according to the present embodiment, the CVT control unit 90 detects a failure signal of the discharge solenoid 53 and switches the supply solenoid 52 to the discharge position when the vehicle speed is less than Vakm / h. Therefore, when the gear ratio is on the low speed side, the supply valve 60 can be shut off and the discharge switch valve 80 can be in communication, preventing an upshift and preparing for re-start / re-acceleration.

  Further, according to the control device 40 according to the present embodiment, the CVT control unit 90 can supply the supply solenoid 52 even when the vehicle speed becomes equal to or higher than Vakm / h after switching the supply solenoid 52 to the discharge position. Since the discharge position is maintained, the speed ratio can be fixed on the low speed side to ensure the minimum vehicle running performance.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. In the above-described embodiment, the supply valve 60, the discharge valve 70, and the discharge switch valve 80 are all of the pilot control type that is driven by the pilot pressure PP, but the present invention is not limited to this. For example, an electromagnetic valve can be used in which the spools 62, 72, 82 of the valves 60, 70, 80 are directly driven by the movable bodies (plungers) of the supply solenoid 52 and the discharge solenoid 53.

  In the above embodiment, the primary pulley 20 is a transmission pulley and the secondary pulley 21 is a tightening pulley. However, the present invention is not limited to this, and the primary pulley 20 is a tightening pulley. The pulley 21 can also be a transmission pulley. In this case, the supply valve 60, the discharge valve 70, and the like are connected to the secondary pulley 21.

10 continuously variable transmission 20 primary pulley (transmission pulley)
21 Secondary pulley (clamping pulley)
22 Drive belt (power transmission element)
40 Control device 41 Oil pump (hydraulic oil supply source)
42 oil pan 52 supply solenoid 53 discharge solenoid 60 supply valve 70 discharge valve (first discharge valve)
80 Discharge switch valve (second discharge valve)
90 CVT control unit (controller)
93 Vehicle speed sensor (vehicle speed detection means)
96 Failure determination unit (failure detection means)

Claims (2)

A transmission pulley and a tightening pulley around which the power transmission element is wound are provided, the supply and discharge of the hydraulic oil to the transmission pulley is adjusted to control the winding diameter of the power transmission element, and the hydraulic oil is supplied to the tightening pulley. A control device for a continuously variable transmission that adjusts exhaust to control a clamping force on the power transmission element,
A hydraulic oil supply source for supplying the hydraulic oil to the transmission pulley and the tightening pulley;
An oil pan for storing the hydraulic oil;
A supply valve provided between the hydraulic oil supply source and the transmission pulley, wherein the supply valve is switched between a communication state for supplying the hydraulic oil to the transmission pulley and a shut-off state for stopping the supply;
A first discharge valve provided between the transmission pulley and the oil pan, wherein the first discharge valve is switched between a communication state for discharging the hydraulic oil from the transmission pulley and a shut-off state for stopping the discharge;
A second discharge valve provided between the first discharge valve and the oil pan, wherein the second discharge valve is switched between a communication state for discharging the hydraulic oil from the first discharge valve and a shut-off state for stopping discharge;
A supply solenoid having a supply position in which the supply valve is in communication and the second discharge valve is shut off, and a discharge position in which the supply valve is shut off and the second discharge valve is in communication;
A discharge solenoid having a communication position for connecting the first discharge valve and a blocking position for blocking the first discharge valve;
A controller for controlling the supply solenoid and the discharge solenoid;
A failure detection means provided in the controller for receiving a failure signal from the discharge solenoid and detecting a failure state of the discharge solenoid ;
Vehicle speed detecting means for detecting a vehicle speed of the vehicle and outputting a vehicle speed signal to the controller;
When the controller detects the failure signal, the controller switches the discharge solenoid to a shut-off position ,
When the vehicle speed signal is equal to or greater than a predetermined value, the supply solenoid is switched to a supply position,
The control device for a continuously variable transmission , wherein the supply solenoid is switched to a discharge position when the vehicle speed signal is less than a predetermined value . 2. The continuously variable transmission control device according to claim 1 , wherein the controller discharges the supply solenoid even when the vehicle speed signal becomes a predetermined value or more after the supply solenoid is switched to the discharge position. A control device for a continuously variable transmission, characterized by maintaining a position.

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