Shift control device

Abstract

To provide a shift control device which can suppress the wear of a parking gear and a parking wheel caused by ratchetting at which a claw of a parking pole is repeatedly flipped by teeth of the parking gear.SOLUTION: An SBW-CU 80 determines whether or not there occurs ratchetting at which a claw of a parking pole 113 is repeatedly flipped by teeth of a parking gear 114 when switching a shift range of a continuously variable transmission 30 to a parking range, and when it is determined that the ratchetting occurs, switches the shift range of the continuously variable transmission 30 to a neutral range. When an average value of a secondary-shaft rotation number per unit time in a prescribed time of a rotation variation is equal to or larger than a prescribed threshold, the SBW-CU 80 determines that the ratchetting occurs.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shift control device for an automatic transmission. [Background technology]

[0002] Conventionally, automatic transmissions mounted on vehicles have used a parking mechanism that includes a parking gear and a parking pole provided on the output shaft, and when the parking (P) position is selected, the parking pole is engaged with the parking gear to lock the rotation of the automatic transmission and place the automatic transmission in a parking state (parking range) (see, for example, Patent Document 1).

[0003] In this type of parking mechanism, when the selector lever is operated to the parking (P) position while driving, if the vehicle speed is equal to or faster than the speed at which the parking gear engages, the teeth of the parking gear repeatedly repel the pawl of the parking pole, creating a so-called ratcheting state, preventing the parking gear and the parking pole from engaging. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-152031 Summary of the Invention [Problem to be solved by the invention]

[0005] However, repeated ratcheting causes wear on the parking gear, parking pole, etc., which reduces the durability of the parking mechanism. In addition, wear on the parking gear, parking pole, etc. may cause contamination, which may accelerate wear on other components or cause valve sticking, for example. There are also known automatic transmissions that have a function (so-called parking inhibit function) that prevents ratcheting from occurring by not switching to the parking range even if the parking (P) position is selected when the vehicle speed is higher than a predetermined set value. However, even with such an automatic transmission, ratcheting may occur if the parking inhibit function fails (breaks down).

[0006] The present invention has been made to solve the above problems, and has an object to provide a shift control device that can suppress wear on the parking gear and parking pole caused by ratcheting, in which the teeth of the parking gear repeatedly repel the pawls of the parking pole. [Means for solving the problem]

[0007] A shift control device according to one aspect of the present invention includes a selection means that receives an operation to select a shift range of an automatic transmission and outputs selection information corresponding to the operation, a control unit that switches the shift range of the automatic transmission according to the selection information output by the selection means, and a parking mechanism that has a parking gear and a parking pole and locks rotation of the automatic transmission by causing the parking pole to mesh with the parking gear, thereby setting the shift range of the automatic transmission to the parking range. When the control unit switches the shift range of the automatic transmission to the parking range, it determines whether ratcheting is occurring, in which the teeth of the parking gear repeatedly repel the pawl of the parking pole, and when it determines that ratcheting is occurring, switches the shift range of the automatic transmission to the neutral range. Effect of the Invention

[0008] According to the present invention, it is possible to suppress wear of the parking gear and the parking pole caused by ratcheting, in which the teeth of the parking gear repeatedly repel the pawl of the parking pole. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a shift control device according to an embodiment, and a powertrain and a driving force transmission system of an AWD vehicle equipped with the shift control device; [Diagram 2] FIG. 2 is a diagram showing the configuration of a parking mechanism of a continuously variable transmission. [Diagram 3] 4 is a flowchart showing a procedure of a shift range (parking range) switching process performed by the shift control device according to the embodiment. [Figure 4] 10 is a flowchart showing a procedure for shift range (parking range) switching processing performed by a shift control device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals will be used for the same or corresponding parts. In each drawing, the same reference numerals will be used for the same elements, and duplicated explanations will be omitted.

[0011] First, the configuration of a shift control device 1 according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a block diagram showing the configuration of the shift control device 1 and the power train and driving force transmission system of an AWD (All Wheel Drive) vehicle equipped with the shift control device 1. Fig. 2 is a diagram showing the configuration of a parking mechanism 110 of a continuously variable transmission (CVT) 30. Note that, in this embodiment, a FF (Front engine Front drive) based part-time AWD vehicle equipped with a shift-by-wire (SBW) type continuously variable transmission 30 will be described as an example.

[0012] The engine 20 may be of any type, but may be, for example, a horizontally opposed, direct-injection, four-cylinder gasoline engine. In the engine 20, air taken in through an air cleaner (not shown) is throttled by an electronically controlled throttle valve (hereinafter, simply referred to as a "throttle valve") provided in an intake pipe, passes through an intake manifold, and is taken in by each cylinder formed in the engine 20. Here, the amount of air taken in through the air cleaner is detected by an air flow meter 71. Furthermore, the throttle valve is provided with a throttle opening sensor 72 that detects the opening of the throttle valve. An injector that injects fuel is attached to each cylinder. Also, each cylinder is provided with an ignition plug that ignites the air-fuel mixture, and an igniter-integrated coil that applies high voltage to the ignition plug. In each cylinder of the engine 20, the air-fuel mixture of the taken in air and the fuel injected by the injector is ignited by the ignition plug and combusted. Exhaust gas after combustion is discharged through an exhaust pipe.

[0013] In addition to the air flow meter 71 and throttle opening sensor 72 described above, a cam angle sensor for identifying the cylinder of the engine 20 is attached near the camshaft of the engine 20. Also, a crank angle sensor 75 for detecting the position of the crankshaft is attached near the crankshaft of the engine 20. These sensors are connected to an engine control unit (hereinafter referred to as "ECU") 70, which will be described later. Also connected to the ECU 70 are various sensors, such as an accelerator pedal sensor 73 for detecting the amount of depression of the accelerator pedal, i.e., the opening degree of the accelerator pedal, and a water temperature sensor 74 for detecting the temperature of the cooling water for the engine 20.

[0014] A torque converter 22 having a clutch function and a torque amplification function, and a continuously variable transmission 30 (corresponding to the automatic transmission described in the claims) that converts and outputs the driving force from the engine 20 are connected to the crankshaft 21 of the engine 20 via a forward / reverse switching mechanism 27.

[0015] The torque converter 22 is mainly composed of a pump impeller 23, a turbine liner 24, and a stator 25. The pump impeller 23 connected to the crank 21 generates a flow of oil, and the turbine liner 24 arranged opposite the pump impeller 23 receives power from the engine 20 via the oil to drive the turbine shaft 31. The stator 25 located between them rectifies the discharge flow (return) from the turbine liner 24 and returns it to the pump impeller 23, thereby generating a torque amplification effect.

[0016] The torque converter 22 also has a lock-up clutch 26 that directly connects the input and output. When the lock-up clutch 26 is not engaged (non-lock-up state), the torque converter 22 amplifies the driving force of the engine 20 and transmits it to the continuously variable transmission 30, and when the lock-up clutch 26 is engaged (lock-up state), the torque converter 22 directly transmits the driving force of the engine 20 to the continuously variable transmission 30. The rotation speed (turbine rotation speed) of the turbine liner 24 that constitutes the torque converter 22 is detected by a turbine rotation sensor 56. The detected turbine rotation speed is output to a transmission control unit (hereinafter referred to as "TCU") 50, which will be described later.

[0017] The forward / reverse switching mechanism 27 switches between forward and reverse rotation (forward and reverse of the vehicle) of the drive wheels 10 (left front wheel 10FL, right front wheel 10FR, left rear wheel 10RL, right rear wheel 10RR). The forward / reverse switching mechanism 27 mainly includes a double pinion type planetary gear train, a forward clutch 28, and a reverse brake 29. The forward / reverse switching mechanism 27 is configured to be able to switch the transmission path of the engine driving force by controlling the respective states of the forward clutch 28 and the reverse brake 29.

[0018] More specifically, when the D (drive) range is selected, the forward clutch 28 is engaged and the reverse brake 29 is disengaged, whereby the rotation of the turbine shaft 31 is transmitted directly to the primary shaft 32, which will be described later, and the vehicle can be driven forward. On the other hand, when the R (reverse) range is selected, the forward clutch 28 is disengaged and the reverse brake 29 is engaged, whereby the planetary gear train is operated to reverse the rotational direction of the primary shaft 32, and the vehicle can be driven backward.

[0019] Furthermore, when the N (neutral) range or the P (parking) range is selected, the forward clutch 28 and the reverse brake 29 are released, thereby separating the turbine shaft 31 from the primary shaft 32 (the transmission of engine driving force is interrupted), and the forward / reverse switching mechanism 27 is in a neutral state in which it does not transmit power to the primary shaft 32. The operations of the forward clutch 28 and the reverse brake 29 are controlled by the TCU 50 and a valve body (control valve) 60.

[0020] The transmission mechanism (variator) 33 of the continuously variable transmission 30 has a primary shaft 32 connected to the turbine shaft 31 of the torque converter 22 via the forward / reverse switching mechanism 27, and a secondary shaft 37 arranged parallel to the primary shaft 32. A primary pulley 34 is provided on the primary shaft 32. The primary pulley 34 has a fixed sheave 34a joined to the primary shaft 32 and a movable sheave 34b opposed to the fixed sheave 34a and attached to the primary shaft 32 so as to be slidable in the axial direction of the primary shaft 32, and is configured to be able to change the cone surface spacing of the sheaves 34a and 34b, i.e., the pulley groove width. On the other hand, a secondary pulley 35 is provided on the secondary shaft 37. The secondary pulley 35 has a fixed sheave 35a joined to the secondary shaft 37 and a movable sheave 35b opposed to the fixed sheave 35a and attached to the secondary shaft 37 so as to be slidable in the axial direction of the secondary shaft 37, and is configured to be able to change the pulley groove width.

[0021] A chain 36 for transmitting driving force is stretched between the primary pulley 34 and the secondary pulley 35. The gear ratio can be changed continuously by changing the groove width of the primary pulley 34 and the secondary pulley 35 to change the ratio of the winding diameter of the chain 36 to each of the pulleys 34, 35 (pulley ratio).

[0022] Here, a hydraulic chamber 34c is formed in the primary pulley 34 (movable sheave 34b). Meanwhile, a hydraulic chamber 35c is formed in the secondary pulley 35 (movable sheave 35b). The groove widths of the primary pulley 34 and the secondary pulley 35 are set and changed by adjusting the primary hydraulic pressure introduced into the hydraulic chamber 34c of the primary pulley 34 and the secondary hydraulic pressure introduced into the hydraulic chamber 35c of the secondary pulley 35.

[0023] A secondary shaft 37 of the speed change mechanism 33 is connected to a counter shaft 39 via a reduction gear 38 consisting of a pair of gears (a reduction drive gear and a reduction driven gear), and the driving force converted by the speed change mechanism 33 is transmitted to the counter shaft 39 via the reduction gear 38. A parking gear 114 constituting a parking mechanism 110 is attached to the counter shaft 39. In other words, the secondary shaft 37 and the counter shaft 39 correspond to the output shaft recited in the claims.

[0024] Here, the parking mechanism 110 of the continuously variable transmission 30 will be described with reference to FIG. 2. The parking mechanism 110 is a mechanism that locks the rotation of the wheels 10 inside the continuously variable transmission when the P (parking) range is selected so that the wheels 10 do not rotate. A detent plate 111 is attached to the output shaft of an SBW actuator 85 (for example, an electric motor) driven by a shift-by-wire control unit (hereinafter referred to as "SBW-CU") 80 described later. A parking rod 112 is connected to the detent plate 111 so as to be movable forward and backward in the axial direction. Meanwhile, as described above, a parking gear 114 is spline-fitted to the counter shaft 39 of the continuously variable transmission 30. Also, a parking pole 113 is provided so as to be swingable so as to be able to mesh with the parking gear 114.

[0025] When the P (parking) range is selected, the SBW actuator 85 (electric motor) is rotated, causing the detend plate 111 to swing and the parking rod 112 to advance in the axial direction. Then, the parking pole 113 is pushed from the back by the tapered portion of the parking rod 112, causing it to swing and mesh with the parking gear 114. This locks the rotation of the continuously variable transmission 30. Note that the parking mechanism 110 is configured such that when the vehicle speed is equal to or higher than a predetermined vehicle speed, the parking pole 113 is repelled by the parking gear 114, and the parking pole 113 and the parking gear 114 cannot mesh with each other.

[0026] Returning to FIG. 1, the counter shaft 39 is connected to a front drive shaft 43 via a counter gear 40 consisting of a pair of gears (counter drive gear, counter driven gear). The driving force transmitted to the counter shaft 39 is transmitted to a front differential (hereinafter also referred to as "front differential") 44 via the counter gear 40 and the front drive shaft 43. The front differential 44 is, for example, a bevel gear type differential device. The driving force from the front differential 44 is transmitted to the left front wheel 10FL via a left front wheel drive shaft 45L, and is also transmitted to the right front wheel 10FR via a right front wheel drive shaft 45R.

[0027] Meanwhile, a transfer clutch 41 for adjusting the driving force transmitted to the rear differential 47 is provided behind the counter gear 40 (counter drive gear) on the counter shaft 39. The fastening force (i.e., torque distribution rate to the rear wheels 10RL, 10RR) of the transfer clutch 41 is controlled according to the driving state of the four wheels (for example, slip state of the front wheels 10FL, 10FR, etc.) and engine torque. Therefore, the driving force transmitted to the counter shaft 39 is distributed according to the fastening force of the transfer clutch 41, and is also transmitted to the rear wheels 10RL, 10RR.

[0028] More specifically, the rear end of the countershaft 39 is connected to a propeller shaft 46 extending toward the rear of the vehicle via a transfer gear 42 consisting of a pair of gears (transfer drive gear, transfer driven gear). Therefore, the driving force transmitted to the countershaft 39 and adjusted (distributed) by the transfer clutch 41 is transmitted from the transfer gear 42 (transfer driven gear) to the rear differential 47 via the propeller shaft 46.

[0029] A left rear wheel drive shaft 48L and a right rear wheel drive shaft 48R are connected to the rear differential 47. Driving force from the rear differential 47 is transmitted to the left rear wheel 10RL via the left rear wheel drive shaft 48L, and is also transmitted to the right rear wheel 10RR via the right rear wheel drive shaft 48R.

[0030] A shift lever 55 that receives a shift operation by the driver is provided on the floor (center console) of the vehicle. A range switch 54 is attached to the shift lever 55 and is connected to move in conjunction with the shift lever 55 to detect the selected position of the shift lever 55. The range switch 54 is connected to the TCU 50, and the detected selected position of the shift lever 55 is read into the TCU 50. That is, the shift lever 55 and the range switch 54 function as a selector as described in the claims. The shift lever 55 can selectively switch between five shift ranges, namely, a parking range (parking (P) range), a reverse driving range (reverse (R) range), a neutral range (neutral (N) range), a forward driving range (drive (D) range), and a manual range (manual (M) range).

[0031] With the driving force transmission system of the powertrain configured as described above, for example, when the shift lever 55 is operated to the D range, the forward clutch 28 is engaged and the engine driving force is input to the primary shaft 32 of the continuously variable transmission 30. The driving force converted by the continuously variable transmission 30 is output from the secondary shaft 37 and transmitted to the front drive shaft 43 via the reduction gear 38, the counter shaft 39, and the counter gear 40. The driving force is then distributed to the left and right by the front differential 44 and transmitted to the left and right front wheels 10FL, 10FR. Therefore, the left and right front wheels 10FL, 10FR are always driven when the vehicle 4 is in a traveling state.

[0032] Meanwhile, a portion of the driving force transmitted to the countershaft 39 is transmitted to a propeller shaft 46 via a transfer clutch 41 and a transfer gear 42. When a predetermined clutch torque is applied to the transfer clutch 41, the driving force distributed in accordance with the clutch torque is output to the propeller shaft 46. The driving force is also transmitted to the rear wheels 10RL, 10RR via a rear differential 47. This allows the vehicle to function as a FF-based part-time AWD vehicle.

[0033] The hydraulic pressure for shifting the continuously variable transmission 30, i.e., the above-mentioned primary hydraulic pressure and secondary hydraulic pressure, are controlled by a valve body (control valve) 60. The valve body 60 adjusts the hydraulic pressure discharged from the oil pump by opening and closing an oil passage formed therein using a spool valve and a solenoid valve (electromagnetic valve) that operates the spool valve, and supplies the hydraulic pressure to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35. Similarly, the valve body 60 adjusts the hydraulic pressure discharged from the oil pump by opening and closing an oil passage formed therein using a spool valve and a solenoid valve that operates the spool valve, and supplies hydraulic pressure for engaging and disengaging each clutch to the forward clutch 28, the reverse brake 29, and the transfer clutch 41.

[0034] The shift control of the continuously variable transmission 30 is executed by the TCU 50. That is, the TCU 50 adjusts the hydraulic pressure supplied to the hydraulic chamber 34c of the primary pulley 34 and the hydraulic chamber 35c of the secondary pulley 35 by controlling the drive of a solenoid valve (electromagnetic valve) constituting the above-mentioned valve body 60, thereby changing the gear ratio of the continuously variable transmission 30. Similarly, the TCU 50 adjusts the hydraulic pressure supplied to the transfer clutch 41 by controlling the drive of a solenoid valve constituting the above-mentioned valve body 60, thereby adjusting the distribution ratio of the driving force transmitted to the rear wheels 10RL, 10RR.

[0035] Furthermore, the TCU 50 adjusts the hydraulic pressure supplied to the forward clutch 28 or the reverse brake 29 by controlling the drive of a clutch linear solenoid 60a constituting a valve body 60, thereby engaging or releasing the forward clutch 28 or the reverse brake 29. Whether the hydraulic pressure (oil) adjusted by the clutch solenoid 60a is supplied to the forward clutch 28 side or the reverse brake 29 side is switched by a manual valve (not shown) that moves in conjunction with a detend plate 111.

[0036] Here, the TCU 50 is connected to an ECU 70 that comprehensively controls the engine 20, an SBW-CU 80, a meter control unit (hereinafter referred to as "MCU") 90, and the like via a CAN (Controller Area Network) 100 so as to be able to communicate with each other.

[0037] The ECU 70 identifies the cylinder from the output of the cam angle sensor, and determines the engine speed from the change in the rotational position of the crankshaft detected by the output of the crank angle sensor 75. The ECU 70 also acquires various information such as the intake air amount, accelerator pedal opening, air-fuel ratio of the mixture, and water temperature based on the detection signals input from the various sensors described above. The ECU 70 then comprehensively controls the engine 20 by controlling the fuel injection amount, ignition timing, and various devices such as the throttle valve based on the acquired information.

[0038] Furthermore, the ECU 70 calculates the engine shaft torque (output torque) of the engine 20 based on the intake air amount detected by the air flow meter 71. The ECU 70 then transmits information such as the engine water temperature (cooling water temperature), the engine shaft torque, the engine speed, and the accelerator pedal opening degree via the CAN 100.

[0039] An output shaft rotation sensor 52 (corresponding to a rotation sensor described in the claims) that is attached near the secondary shaft 37 of the continuously variable transmission 30 and detects the rotation speed of the secondary shaft 37, and a primary pulley rotation sensor 53 that detects the rotation speed of the primary pulley 34 are connected to the TCU 50. For example, a magnetic pickup or an MR element is preferably used as the output shaft rotation sensor 52 and the primary pulley rotation sensor 53. A range switch 54 that detects the selected position (shift position) of the shift lever 55 is also connected to the TCU 50. Furthermore, the above-mentioned turbine rotation sensor 56, an oil temperature sensor 57 that detects the oil temperature of the continuously variable transmission 30, and the like are also connected to the TCU 50.

[0040] The TCU 50 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and various maps for causing the microprocessor to execute each process, a RAM that stores various data such as the results of calculations, a backup RAM whose stored contents are maintained by a battery, and an input / output I / F.

[0041] The TCU 50 automatically and steplessly changes the gear ratio according to the vehicle operating conditions (for example, accelerator pedal opening, vehicle speed, or engine speed) in accordance with a shift map. The shift map is stored in an EEPROM or the like in the TCU 50. The TCU 50 also executes transfer clutch control (AWD control) based on various information acquired from the above-mentioned various sensors and the like. The TCU 50 transmits various information such as the shift position and secondary shaft speed to the SBW-CU 80 via the CAN 100.

[0042] The SBW-CU80 receives various information such as the shift position and the output shaft rotation speed via the CAN100. The SBW-CU80 generates and outputs a control signal (motor drive signal) based on the received various information including the shift position, and drives the SBW actuator 85. The SBW-CU80 functions as a control unit as recited in the claims. The SBW-CU80 also transmits information indicating that ratcheting is occurring (described in detail below) to the MCU90 via the CAN100.

[0043] The SBW actuator 85 operates a manual valve (not shown) linked to the detend plate 111 in response to a control signal from the SBW-CU 80 to switch the shift range of the continuously variable transmission 30. The SBW-CU 80 and the SBW actuator 85 may be integrally configured. As the SBW actuator 85, for example, an electric motor is preferably used.

[0044] In particular, the SBW-CU80 has a function of suppressing wear of the parking gear 114 and the parking pole 113 caused by ratcheting, in which the teeth of the parking gear 114 repeatedly repel the pawls of the parking pole 113. In the SBW-CU80, the above functions are realized by a microprocessor executing a program stored in an EEPROM or the like.

[0045] When switching the shift range of the continuously variable transmission 30 to the parking range while traveling, the SBW-CU80 determines whether or not ratcheting is occurring (detects the occurrence of ratcheting), in which the teeth of the parking gear 114 repeatedly repel the pawls of the parking pole 113. When the SBW-CU80 determines that ratcheting is occurring (detects the occurrence of ratcheting), it automatically switches the shift range of the continuously variable transmission 30 to the neutral range.

[0046] More specifically, the SBW-CU 80 first obtains the rotational fluctuation (rotational fluctuation rate) of the rotation speed of the secondary shaft 37 per unit time (for example, per sampling period) based on the following equation (1). Rotation speed fluctuation rate = {(current value - previous value) / previous value}*100 (1)

[0047] Then, the SBW-CU80 determines that ratcheting is occurring when the rotational fluctuation (rotational fluctuation rate) of the rotational speed of the secondary shaft 37 per unit time (per sampling period) is equal to or greater than a predetermined threshold value (e.g., 20%). In particular, the SBW-CU80 determines that ratcheting is occurring when the average value of the rotational fluctuation (rotational fluctuation rate) in a predetermined time (e.g., one second) is equal to or greater than a predetermined threshold value (e.g., 20%).

[0048] This method of determining (detecting) ratcheting is based on the knowledge that in a ratcheting state in which the parking gear 114 is continuously hitting the parking pawl 113, a noise-like whisker-like waveform appears in the output signal of the output shaft rotation sensor 52 due to the influence of gear backlash, etc.

[0049] It is preferable that the SBW-CU80 varies the above-mentioned predetermined time in accordance with the vehicle speed. For example, the SBW-CU80 shortens the above-mentioned predetermined time as the vehicle speed increases. This is because the appearance period of the whisker-like waveform described above becomes shorter as the vehicle speed increases. It is to be noted that the above-mentioned predetermined time and threshold value can be set arbitrarily in accordance with, for example, the backlash of the shafts and the specifications of the operation system parts.

[0050] Information (abnormal information) indicating that the ratcheting described above is occurring and information indicating that the shift range has been automatically switched to the neutral range are sent to the MCU 90 via the CAN 100. The MCU 90 is connected to a display unit 91 having an LCD display or the like disposed, for example, in a meter or on the top of a dashboard, and drives the display unit 91 to present, for example, the status and various information of the vehicle, the engine 20, the continuously variable transmission 30, etc., to the driver.

[0051] In particular, the MCU 90 issues a warning to the driver when ratcheting is detected or when the shift range is automatically switched to the neutral range. That is, the MCU 90 and the display unit 91 function as a presentation unit as described in the claims. At that time, the MCU 90 preferably drives the display unit 91 to, for example, turn on a warning light or display text such as "Ratcheting is occurring" or "The shift range has been switched to neutral." In addition, a warning sound may be output at the same time.

[0052] Next, the operation of the shift control device 1 will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the procedure of shift range (parking range) switching processing by the shift control device 1. This processing is mainly executed repeatedly at a predetermined timing by the SBW-CU 80.

[0053] In step S100, information such as the secondary shaft rotation speed and vehicle speed is read.

[0054] Next, in step S102, it is determined whether or not the P range has been selected (whether or not there is a request to switch to the P range) while traveling (for example, at a vehicle speed of 10 km / h or more), that is, whether or not the shift lever 55 has been switched from the D range to the P range or from the R range to the P range. If the P range has not been selected, the process is temporarily terminated. On the other hand, if the P range has been selected, the process proceeds to step S104.

[0055] In step S104, the operation of switching to the P range is started. That is, the driving of the SBW actuator 85 (parking pole 113) is started.

[0056] Next, in step S106, it is determined whether or not ratcheting is occurring. The method for determining whether or not ratcheting is occurring is as described above, and therefore detailed description will be omitted here. If ratcheting is not occurring, the process is temporarily terminated. On the other hand, if ratcheting is occurring, the process proceeds to step S108.

[0057] In step S108, the shift range of the continuously variable transmission 30 is automatically switched to the neutral range. Then, in the following step S110, information indicating that ratcheting is occurring (abnormal information) and information indicating that the shift range has been automatically switched to the neutral range are presented. After that, the process temporarily exits.

[0058] As described above in detail, according to this embodiment, when the occurrence of ratcheting is detected, the shift range is automatically switched to the neutral range. This eliminates the ratcheting. As a result, even if the parking range is selected while driving due to an erroneous operation, it is possible to suppress wear of the parking gear 114 and the parking pole 113 caused by ratcheting.

[0059] According to this embodiment, the rotational fluctuation (rotational fluctuation rate) of the secondary shaft rotation speed per unit time (per sampling period) is obtained, and if the average value of the rotational fluctuation (rotational fluctuation rate) over a predetermined time (e.g., one second) is equal to or greater than a predetermined threshold value (e.g., 20%), it is determined that ratcheting is occurring. Therefore, ratcheting can be detected with high accuracy while preventing erroneous determination (false detection).

[0060] According to this embodiment, when it is determined that ratcheting is occurring or when the shift range is automatically switched to the neutral range, information indicating that ratcheting is occurring (abnormal information) or information indicating that the shift range has automatically been switched to the neutral range is presented to the driver, etc. Therefore, it is possible to make the driver, etc. aware that ratcheting is occurring or that the shift range has been switched to neutral.

[0061] According to this embodiment, the predetermined time for calculating the average value of the rotational fluctuation (rotational fluctuation rate) of the secondary shaft rotational speed (the predetermined time for determining whether or not ratcheting has occurred) is made shorter as the vehicle speed increases, so that it is possible to more quickly detect whether or not ratcheting has occurred while preventing erroneous detection.

[0062] According to this embodiment, the occurrence of ratcheting can be detected using the output shaft rotation sensor 52 that detects the rotation speed of the secondary shaft 37 (the rotation speed of the secondary pulley 35) of the continuously variable transmission 30. In other words, an existing rotation sensor can be used (reused). Therefore, there is no need to provide a new rotation sensor, and increases in costs and man-hours can be suppressed.

[0063] Next, a shift range (parking range) switching process in a case where the shift control device has a parking inhibit function will be described with reference to Fig. 4. Fig. 4 is a flowchart showing a process procedure of a shift range (parking range) switching process by a shift control device having a parking inhibit function (a shift control device according to a modified example).

[0064] In step S200, information such as the secondary shaft rotation speed and vehicle speed is read.

[0065] Next, in step S202, it is determined whether or not the P range has been selected (whether or not there is a request to switch to the P range) while traveling (for example, at a vehicle speed of 10 km / h or more), that is, whether or not the shift lever 55 has been switched from the D range to the P range or from the R range to the P range. If the P range has not been selected, the process is temporarily terminated. On the other hand, if the P range has been selected, the process proceeds to step S204.

[0066] In step S204, it is determined whether the parking inhibit function has failed (whether there is a malfunction). If the parking inhibit function has failed, the process proceeds to step S206. On the other hand, if the parking inhibit function is normal, switching to the parking range is prohibited in step S214, and then the process temporarily exits.

[0067] In step S206, the operation of switching to the P range is started. That is, the driving of the SBW actuator 85 (parking pole 113) is started.

[0068] Next, in step S208, it is determined whether or not ratcheting is occurring. The method for determining whether or not ratcheting is occurring is as described above, so a detailed description will be omitted here. If ratcheting is not occurring, the process is temporarily terminated. On the other hand, if ratcheting is occurring, the process proceeds to step S210.

[0069] In step S210, the shift range of the continuously variable transmission 30 is automatically switched to the neutral range. Then, in the following step S212, information indicating that ratcheting is occurring (abnormal information) and information indicating that the shift range has been automatically switched to the neutral range are presented. After that, the process temporarily exits.

[0070] In this way, even if the parking inhibit function fails, it is possible to suppress wear of the parking gear 114 and the parking pole 113 caused by ratcheting.

[0071] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the present invention is applied to a chain-type continuously variable transmission (CVT), but instead of the chain-type continuously variable transmission, the present invention can also be applied to, for example, a belt-type continuously variable transmission or a toroidal-type continuously variable transmission. Also, instead of the continuously variable transmission, the present invention can also be applied to a stepped automatic transmission (step AT). Also, in the above embodiment, the AWD vehicle is used as an example, but the present invention can also be applied to, for example, a FF vehicle. Furthermore, the present invention can also be applied to HEVs (hybrid vehicles), PHEVs (plug-in hybrid vehicles), EVs (electric vehicles), FCVs (fuel cell vehicles), and the like.

[0072] In the above embodiment, the TCU50, the ECU70, the SBW-CU80, and the MCU90 are connected to each other so that they can communicate with each other via the CAN100, but the system configuration is not limited to this form and can be changed arbitrarily, for example, taking into consideration functional requirements, costs, and the like. For example, the SBW-CU80 and the SBW actuator 85 may be integrated, or the TCU50 and the SBW-CU80 may be formed as a single unit. In the above embodiment, the detection of ratcheting, etc. is performed by the SBW-CU80, but the TCU50 may be configured to perform the detection.

[0073] In the above embodiment, the output shaft rotation sensor 52 provided on the secondary shaft 37 is used to detect ratcheting, but other rotation sensors may be used as long as they can detect rotation fluctuations caused by ratcheting. For example, a rotation speed sensor that detects the rotation speed of the counter shaft 39 or a primary pulley rotation sensor 53 that detects the rotation speed of the primary pulley 34 may be used.

[0074] In addition, the above-mentioned configuration of the drive force transmission system (e.g., the arrangement of gears, shafts, etc.) is one example and is not limited to the above embodiment. For example, in the above embodiment, the forward / reverse switching mechanism 27 is arranged upstream of the transmission mechanism (variator) 33, but it may be arranged downstream of the transmission mechanism 33. [Explanation of symbols]

[0075] 1 Shift control device 20 Engine 22 Torque converter 27 Forward / reverse switching mechanism 28 Forward clutch 29 Reverse brake 30 Continuously variable transmission 33 Transmission mechanism 37 Secondary Axis 39 Counter shaft 41 Transfer clutch 50 TCU 52 Output shaft rotation sensor 53 Primary pulley rotation sensor 54 Range switch 55 Shift lever 56 Turbine rotation sensor 57 Oil temperature sensor 60 Valve body 70 ECU 80SBW-CU 85 SBW actuator 90 MCU 91 Display section 100 CAN 110 Parking mechanism 113 Parking Pole 114 Parking Gear

Claims

1. a selector means for receiving an operation for selecting a shift range of the automatic transmission and outputting selection information corresponding to the operation; a control unit for switching a shift range of the automatic transmission in response to selection information output by the selector means; a parking mechanism having a parking gear and a parking pole, the parking pole being engaged with the parking gear to lock rotation of the automatic transmission and set the shift range of the automatic transmission to a parking range; a rotation sensor that detects the rotation speed of an output shaft of the automatic transmission to which the parking gear is provided, the control unit determines whether or not ratcheting, in which a claw of the parking pole is repeatedly repelled by teeth of the parking gear, occurs when the shift range of the automatic transmission is switched to a parking range, and when it determines that ratcheting is occurring, switches the shift range of the automatic transmission to a neutral range; When determining whether or not ratcheting is occurring, the control unit determines that ratcheting is occurring when an average value of a rotational fluctuation in the rotational speed of the output shaft per unit time over a predetermined time period is equal to or greater than a predetermined threshold value, The control unit is further configured to vary the predetermined time period in response to a vehicle speed.

2. 2. The shift control device according to claim 1, further comprising a notification unit that notifies the user that ratcheting is occurring when the control unit determines that ratcheting is occurring.

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