[0001] The present disclosure relates to an electronically controlled transmission, and more particularly to systems and methods for electronically controlling a sub- transmission of a recreational vehicle.

[0002] Some recreational vehicles, such as all-terrain vehicles (ATV's), utility vehicles, motorcycles, etc., include a continuously variable transmission (CVT). In these vehicles, an actuator adjusts the position of one of the primary and secondary clutches of the CVT to change the gear ratio. Other recreational vehicles include a hydrostatic transmission.

[0003] In recreational vehicles with a CVT or hydrostatic transmission, a separate sub-transmission is typically coupled to an output of the CVT or hydrostatic transmission for shifting between park, neutral, reverse, and forward gear configurations. Sub- transmissions, also referred to as a range box, are mechanically linked to a shifter located in the operator area. The mechanical linkage may include cables and other linkages. The mechanical components of the shift system occupy space in the vehicle and require maintenance over time due to wear and corrosion. Further, shifting the sub- transmission under improper vehicle conditions may result in damage to the powertrain of the vehicle. [0004] In an illustrated embodiment of the present disclosure, a recreational vehicle is provided including a chassis, a ground engaging member configured to support the chassis, and a power source supported by the chassis. The power source includes at least one of an engine and an electric motor. The vehicle further includes a

transmission including at least one of a continuously variable transmission and a hydrostatic transmission. The transmission is driven by the power source and has an adjustable gear ratio. The vehicle further includes a sub-transmission coupled to the transmission. The sub-transmission has a plurality of selectable gear configurations including a forward gear and at least one of a park gear, a neutral gear, and a reverse gear. The vehicle further includes an actuator operative to change a gear configuration of the sub-transmission. The vehicle further includes a shift device having a signal output operative to provide a shift request signal indicative of a request to change the gear configuration of the sub-transmission. The vehicle further includes a controller including at least one processor. The controller is operative to control the gear ratio of transmission and is in communication with the shift device and the actuator. The controller is operative to control the actuator to change the gear configuration of the sub-transmission in response to detecting the shift request signal provided by the shift device. [0005] In another illustrated embodiment of the present disclosure, a method of controlling a sub-transmission of a recreational vehicle is provided. The method includes controlling, by a controller of the vehicle, an output speed of a power source of the vehicle. The controller includes at least one processor. The power source includes at least one of an engine and an electric motor. The method further includes controlling, by the controller, a gear ratio of a transmission of the vehicle. The transmission includes at least one of a continuously variable transmission and a hydrostatic transmission. The transmission is driven by the power source. The method further includes detecting, by the controller, a shift request signal provided by a shift device. The shift request signal indicates a request to shift a sub-transmission of the vehicle to a target gear configuration. The sub-transmission is coupled to and driven by an output of the transmission and has a plurality of selectable gear configurations including a forward gear and at least one of a park gear, a neutral gear, and a reverse gear. The method further includes controlling an actuator to change a gear configuration of the sub-transmission to the target gear configuration based on the shift request signal. [0006] In yet another illustrated embodiment of the present disclosure, a non- transitory computer-readable medium is provided. The computer-readable medium includes executable instructions such that when executed by at least one processor cause the at least one processor to control an output speed of a power source of a vehicle. The power source includes at least one of an engine and an electric motor. The executable instructions when executed by the at least one processor further cause the at least one processor to control a gear ratio of a transmission of the vehicle. The transmission includes at least one of a continuously variable transmission and a hydrostatic transmission and is driven by the power source. The executable instructions when executed by the at least one processor further cause the at least one processor to detect a shift request signal provided by a shift device. The shift request signal indicates a request to shift a sub-transmission of the vehicle to a target gear

configuration. The sub-transmission is driven by an output of the transmission and has a plurality of selectable gear configurations including a forward gear and at least one of a park gear, a reverse gear, and a neutral gear. The executable instructions when executed by the at least one processor further cause the at least one processor to control an actuator to change a gear configuration of the sub-transmission to the target gear configuration based on the shift request signal.

[0007] The invention will now be described by way of reference to the drawing figures, where:

[0008] FIG. 1 is a perspective view of an exemplary vehicle incorporating the electronically controlled sub-transmission of the present disclosure;

[0009] FIG. 2 is a block diagram of an exemplary control system of the vehicle of FIG. 1 including a continuously variable transmission (CVT) and a sub-transmission; [0010] FIG. 3 is a block diagram of an exemplary implementation of the control system of FIG. 2 including a vehicle control module in communication with an engine control module;

[0011] FIG. 4 is a block diagram illustrating an exemplary control strategy for electronically controlling the sub-transmission of FIG. 2; [0012] FIG. 5 is a block diagram illustrating another exemplary control strategy for electronically controlling the sub-transmission of FIG. 2; [0013] FIG. 6 is a perspective partial side view of the vehicle of FIG. 1 illustrating a shift device and a steering wheel according to an embodiment;

[0014] FIG. 7 is a perspective top view of the shift device of FIG. 6 including control input devices for controlling an accessory; and [0015] FIG. 8 is a perspective view of another exemplary vehicle incorporating the electronically controlled sub-transmission of the present disclosure.

[0016] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

[0017] The embodiments disclosed herein are not intended to be exhaustive or limit the disclosure to the precise forms disclosed in the following detailed description.

Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. [0018] The term "logic" or "control logic" as used herein may include software and/or firmware executing on one or more programmable processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), hardwired logic, or combinations thereof. Therefore, in accordance with the embodiments, various logic may be implemented in any appropriate fashion and would remain in accordance with the embodiments herein disclosed.

[0019] Referring initially to FIG. 1 , an exemplary vehicle 10 is illustrated that includes an electronically controlled sub-transmission as disclosed herein. Vehicle 10 is illustratively a side-by-side ATV 10 including a front end 12, a rear end 14, and a frame or chassis 15 that is supported above the ground surface by ground engaging members in the form of a pair of front wheels 24a including tires 22a and a pair of rear wheels 24b including tires 22b. Vehicle 10 includes a pair of laterally spaced-apart bucket seats 18a, 18b, although a bench style seat or any other style of seating structure may be used. Seats 18a, 18b are positioned within a cab 17 of vehicle 10. A protective roll cage 16 extends over cab 17 to reduce the likelihood of injury to passengers of vehicle 10 from passing branches or tree limbs and to serve as a support in the event of a vehicle rollover. Roll cage 16 includes a plurality of support bars and, in one

embodiment, is comprised of a metal material. Cab 17 also includes front dashboard 31 , adjustable steering wheel (steering device) 28, and shift lever 29. Front dashboard 31 may include a tachometer, speedometer, a display (e.g., display 106 of FIG. 2), or any other suitable instrument.

[0020] Front end 12 of vehicle 10 includes a hood 32 and a front suspension assembly 26. Front suspension assembly 26 pivotally couples front wheels 24a to vehicle 10. Rear end 14 of vehicle 10 includes an external storage platform 19 which serves as an engine cover extending over a power source, such as an engine 42 (see FIG. 2). Storage platform 19 is configured to secure or store one or more objects during operation of vehicle 10. Rear end 14 further includes a rear suspension assembly (not shown) pivotally coupling rear wheels 24b to vehicle 10. In one embodiment, a body of vehicle 10 is made of a plastic, including for example hood 32, storage platform 19, and/or side panels of vehicle 10. Other suitable vehicles may be provided that incorporate the drive system and control strategies described herein, such as a snowmobile, a straddle-seat ATV (e.g., see vehicle 310 of FIG. 8), a utility vehicle, a motorcycle, and other recreational and non-recreational vehicles.

[0021] Referring to FIG. 2, an exemplary control system 40 of vehicle 10 of FIG. 1 is illustrated including an engine 42 and a continuously variable transmission (CVT) 48. CVT 48 includes a primary or drive clutch 50 and a secondary or driven clutch 52. An endless, variable speed belt 54 is coupled to the primary and secondary clutches 50, 52. Engine 42 includes an output shaft 44 configured to drive primary clutch 50 of CVT 48. Rotation of primary clutch 50 is transferred to secondary clutch 52 via belt 54. An output shaft 46 of secondary clutch 52 is coupled to and drives a sub-transmission 56, and an output shaft 74 of sub-transmission 56 is coupled to a final drive 58 for driving wheels 24 (see FIG. 1 ). In one embodiment, sub-transmission 56 is geared to provide a high forward gear, a low forward gear, a reverse gear, a neutral gear, and a park configuration for vehicle 10 of FIG. 1 . Fewer or additional gear configurations may be provided with sub-transmission 56. Final drive 58 includes drive line components downstream of sub-transmission 56, including an output shaft, one or more axles, differential(s), and driven wheels 24, for example.

[0022] An electronic controller 36 of control system 40 is operative to control CVT 48, engine 42, and sub-transmission 56, as described herein. Controller 36 includes at least one processor 38 that executes software and/or firmware stored in memory 39 of controller 36. The software/firmware code contains instructions that, when executed by processor 38, causes controller 36 to perform the functions described herein. Controller 36 may alternatively include one or more application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), hardwired logic, or combinations thereof. The processor(s) 38 of controller 36 illustratively include engine control logic 33 operative to control engine 42, CVT control logic 34 operative to control CVT 48, and sub-transmission control logic 35 operative to control sub- transmission 56. Controller 36 may be a single control unit or multiple control units functioning together to perform the functions of controller 36 described herein.

Controller 36 may include additional components for routing signals to and from controller 36. Engine control logic 33, CVT control logic 34, and sub-transmission logic 35 may be provided on a same processing device or two or more different processing devices. For example, in one embodiment CVT control logic 34 and sub-transmission logic 35 are provided on a designated vehicle or transmission control module physically separate from and in communication with an engine control module (ECM) of vehicle 10 that contains engine control logic 33. Other suitable controller arrangements may be provided.

[0023] Memory 39 is any suitable computer readable medium that is accessible by processor 38. Memory 39 may be a single storage device or multiple storage devices, may be located internally or externally to controller 36, and may include both volatile and non-volatile media. Exemplary memory 39 includes random-access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, CD-ROM, Digital Versatile Disk (DVD) or other optical disk storage, a magnetic storage device, or any other suitable medium which is configured to store data and which is accessible by controller 36. [0024] Primary clutch 50 of CVT 48 rotates on a shaft that is driven by the output shaft 44 of engine 42. In one embodiment, primary clutch 50 includes a stationary sheave and a moveable sheave that moves relative to the stationary sheave to adjust the gear ratio. CVT control logic 34 of controller 36 is operative to control an actuator assembly 80 for controlling the position of the moveable sheave of primary clutch 50 and thus the gear ratio of CVT 48. In particular, actuator assembly 80 includes a motor 76 controlled by CVT control logic 34 that adjusts primary clutch 50 to provide a target gear ratio. In an exemplary embodiment, motor 76 is an electric motor such as a stepper motor, for example, although another suitable electric or hydraulic motor may be provided. In one embodiment, actuator assembly 80 and/or controller 36 includes a motor drive that controls motor 76 based on control signals provided with CVT control logic 34. Alternatively, CVT control logic 34 may control a relay for selectively routing power to motor 76 for controlling motor 76.

[0025] In one embodiment, secondary clutch 52 is a mechanically controlled clutch 52 and includes a stationary sheave and a moveable sheave (not shown). Secondary clutch 52 is configured to control the tension of belt 54 of CVT 48 as primary clutch 50 is adjusted. In an alternative embodiment, controller 36 and actuator assembly 80 may further control secondary clutch 52 of CVT 48. A shaft 46 of secondary clutch 52 drives sub-transmission 56 (see FIG. 2). Belt 54 wraps around the primary and secondary clutches 50, 52 and transfers rotational motion of primary clutch 50 to secondary clutch 52.

[0026] A clutch assembly 45 is coupled to output shaft 44 of engine 42 to serve as a starting or launch clutch for primary clutch 50. In one embodiment, clutch assembly 45 is a dry centrifugal clutch integrated into primary clutch 50. Clutch assembly 45 is disengaged from primary clutch 50 when engine 42 is at engine idle speed. As the engine speed and the corresponding rotational speed of clutch assembly 45 increases to a threshold speed greater than engine idle speed, the centrifugal force acting on clutch assembly 45 forces clutch assembly 45 into engagement with primary clutch 50. When the rotational speed of shaft 44 decreases below the threshold clutch

engagement speed, the reduced centrifugal force causes clutch assembly 45 to disengage from primary clutch 50 of CVT 48.

[0027] For additional details of an exemplary CVT 48, see U.S. Patent Application No. 13/652,253, filed October 15, 2012, entitled PRIMARY CLUTCH ELECTRONIC CVT, the entire disclosure of which is expressly incorporated by reference herein.

[0028] Sub-transmission control logic 35 of FIG. 2 is operative to control an actuator 57 for controlling a gear position of sub-transmission 56. In one embodiment, actuator 57 is mounted to sub-transmission 56. In an exemplary embodiment, actuator 57 includes an electric motor, such as a stepper motor or other suitable motor, although any suitable actuator 57 may be provided. Controller 36 and/or actuator 57 includes a motor drive that controls the motor based on control signals provided with sub- transmission control logic 35. Alternatively, sub-transmission control logic 35 may control a relay for selectively routing power to actuator 57 for controlling actuator 57. In one embodiment, actuator 57 includes a manual override that allows sub-transmission 56 to be manually shifted by an operator with a mechanical tool.

[0029] Still referring to FIG. 2, a throttle operator 60 including a position sensor is coupled to an input of controller 36, and engine control logic 33 electronically controls the position of a throttle valve 62 of engine 42 based on the detected position of throttle operator 60 to regulate air intake to and thus the speed of engine 42. Throttle operator 60 may include an accelerator pedal, a thumb actuated lever, a twist grip, or any other suitable throttle input device that, when actuated by an operator, is configured to provide an operator throttle demand to controller 36. For additional disclosure of electronic throttle control provided with controller 36, see U.S. Patent Application No. 13/152,981 , filed June 3, 201 1 , entitled ELECTRONIC THROTTLE CONTROL, the entire disclosure of which is expressly incorporated by reference herein.

[0030] A brake operator 68 including a position or pressure sensor is also coupled to an input of controller 36. Brake operator 68 includes, for example, a foot pedal, a hand brake, or another suitable brake input device. Controller 36 detects an application (e.g., actuation) of brake operator 68 based on a signal provided by the position or pressure sensor of brake operator 68.

[0031] A display 106 is coupled to controller 36 for displaying vehicle operation information to an operator. Exemplary information provided on display 106 includes vehicle speed, engine speed, fuel level, clutch position or gear ratio of CVT 48, gear configuration of sub-transmission 56, selected operating mode, and other suitable information.

[0032] Vehicle 10 further includes one or more shifters 55 actuated by an operator for sending shift requests to controller 36 for shifting between gears of sub-transmission 56, as described herein. In one embodiment, shifter 55 includes shift device 29 of

FIGS. 1 , 6, and 7. Speed sensors 59 provide signals to controller 36 representative of an engine speed, a wheel (ground) speed, a rotational speed of primary clutch 50 and/or secondary clutch 52, and/or a speed of other components of the vehicle drive train. One or more mode selection devices 64 in communication with controller 36 are actuated by an operator to select an operating mode of vehicle 10. Exemplary operating modes include a plow mode, a work mode, a snow/ice mode, a sport mode, a learner mode, and other suitable modes. In one embodiment, engine control logic 33 provides variable throttle response curves based on the selected mode, for example as described in U.S. Patent Application No. 13/152,981 , filed June 3, 201 1 , entitled ELECTRONIC THROTTLE CONTROL, the entire disclosure of which is expressly incorporated by reference herein. Mode selection device 64 includes a toggle switch or a code entered via display 106, for example. In one embodiment, mode selection device 64 includes an ignition key having an identifier (e.g., RFID) that is readable by controller 36 for selecting a particular mode of operation. As described herein, sub- transmission 56 is controlled based on the selected operating mode.

[0033] A seat sensor or switch 66 in communication with controller 36 provides signal feedback to controller 36 indicative of the presence or absence of a load (i.e., an operator) positioned in seat 18a (and/or seat 18b) of FIG. 1 (or seat 318 of FIG. 8). In one embodiment, controller 36 determines seat 18a is in a loaded state in response to detecting with sensor 66 a force on seat 18a greater than or equal to a predetermined threshold force and that seat 18a is in an unloaded state in response to the detected force being less than the threshold force. An exemplary threshold force is 50 pounds or any other suitable force. For additional details of an exemplary seat sensor 66, see U.S. Patent Application No. 13/725,361 , filed December 21 , 2012, entitled SIDE-BY- SIDE DIESEL UTILITY VEHICLE, the entire disclosure of which is expressly

incorporated by reference herein.

[0034] Vehicle 10 includes one or more inclinometers 70 in communication with controller 36 for detecting an incline or angle of vehicle relative to a horizontal plane. Vehicle 10 further includes a system battery 72 (e.g. 12 VDC) configured to provide power for starting vehicle 10 and to provide peripheral power to vehicle 10 during operation. In one embodiment, controller 36 communicates with one or more

sensors/devices and/or controllers of vehicle 10 via controller area network (CAN) communication.

[0035] Controller 36 of FIG. 2 is operative to electronically shift sub-transmission 56 based on a shift request provided with shifter 55. In the illustrated embodiment, sub- transmission 56 includes a high-range forward gear, a low-range forward gear, a low- range reverse gear, a neutral gear, and a park gear. The low range forward gear provides increased power and lower speed operation than the high range forward gear. For example, the low range gear may be used for towing, plowing, rock crawling, hauling, or other work operations, and the high range gear may be used for traveling at higher speeds or in non-loaded conditions. Other suitable gear configurations of sub- transmission 56 may be provided.

[0036] FIG. 3 illustrates one exemplary configuration 100 of control system 40 of FIG. 2 for controlling electronic shifting of sub-transmission 56. Referring to FIG. 3, controller 36 of FIG. 2 includes a vehicle control module (VCM) 102 (or transmission control module TCM) in communication with an engine control module (ECM) 104. A sensor 108 of shifter 55 (FIG. 2) is a rotary position sensor that senses the "Requested Gear" from the user and transmits that information via analog signal to VCM 102.

Another suitable signal output may be provided with shifter 55 that is configured to output a shift request signal indicative of an actuation of shifter 55. A sensor 1 10 on a shift drum of sub-transmission 56 (FIG. 2) is a rotary position sensor that senses the "Current Gear" of sub-transmission 56 and transmits that information via analog signal to VCM 102. Sensors 108 and 1 10 may alternatively transmit digital signals. Sensors 108 and 1 10 illustratively include redundant signal lines 1 14 as well as full redundant power supply and ground lines 1 14 to increase the likelihood of desired operation. In one embodiment, full diagnostics are available on these inputs. VCM 102 also includes redundancy checks in the software on the signal lines 1 14 so that the correct gear is requested and determined.

[0037] ECM 104 broadcasts out "RPM" and "Wheel Speed" CAN signals via lines 1 16 and receives the "Current Gear" from VCM 102. If the "Current Gear" is unknown from VCM 102, ECM 104 defaults to a backup gear determination by accessing a memory lookup table based on RPM and Wheel Speed to determine the current gear of sub-transmission 56.

[0038] VCM 102 receives the analog inputs 1 14 as well as "RPM" and "Wheel Speed" inputs from ECM 104 via CAN lines 1 16 to make decisions on whether to execute a shift request from the user. In one embodiment, VCM 102 does not allow a shift above a calibrated RPM or wheel speed threshold to protect the transmission from unintended damage, as described herein. In certain conditions, VCM 102 disables electronic shifting and defaults to a "Mechanical Override Mode" if VCM 102 determines sub-transmission 56 cannot suitably shift, such as due to a loss of an input signal (e.g,. signal from sensor 1 10, ECM 104, or an interlock described herein), for example. In Mechanical Override Mode, sub-transmission 56 may be shifted via a mechanical tool, such as a wrench or other tool.

[0039] An electric direct current (DC) motor 1 12 of actuator 57 (FIG. 2) receives a signal from VCM 102 to shift sub-transmission 56 to the requested gear. In one embodiment, current sensing and full diagnostics are available on this output from VCM 102. VCM 102 includes an H-bridge 120 that drives the DC control of motor 1 12 via lines 1 18. H-bridge 120 includes an electronic circuit configured to enable voltage to be applied to motor 1 12 in either direction to rotate the output shaft 44 of motor 1 12 in either direction, thereby allowing shifting in either direction through the gear range. In the illustrated embodiment, H-bridge 120 is located in the VCM 102 and is remote from motor 1 12. An analog or digital signal is output by H-bridge 120 to drive output shaft 44 of motor 1 12 a known rotational distance in the forward or reverse direction. VCM 102 detects the current position of motor 1 12 via shift drum sensor 1 10. VCM 102 stores calibrated set points identifying a rotational position of output shaft 44 of motor 1 12 that corresponds to each gear. Position tolerances are detected by controller 36 via H- bridge 120 based on a detected voltage, such as a zero to five volt signal. Controller 36 commands a target rotational position of output shaft 44 of motor 1 12 based on a target rotational position of output shaft 44 and a known tolerance.

[0040] In the illustrated embodiment, sub-transmission 56 includes adaptive range sensors (e.g., sensor 1 10) that provide position feedback to VCM 102. VCM 102 is operative to tighten tolerances for each gear position. In particular, by identifying the actual transmission position from sensor 1 10 and identifying the position tolerances, VCM 102 is operative to drive sub-transmission 56 to a predefined position.

[0041] Display 106 receives both "Requested Gear" and "Current Gear" from the CAN bus 1 16 and displays the "Requested Gear" when it matches "Current Gear." If "Requested Gear" and "Current Gear" do not match, display 106 flashes the "Requested Gear" to provide an indication to the user that a gear shift has been requested but not executed based on suitability checks not being met in VCM 102.

[0042] Referring to FIG. 4, a flow diagram 200 is illustrated of an exemplary operation performed by controller 36 of FIG. 2 for electronically shifting sub- transmission 56. Reference is made to FIG. 2 throughout the following description of FIG. 4. At block 202, controller 36 detects a shift request initiated with shift device 55 that identifies a target gear configuration of sub-transmission 56. Controller 36 determines the current gear configuration of sub-transmission 56 at block 204 based on output from a position sensor (e.g., shift drum sensor 1 10 of FIG. 3). At block 206, controller 36 detects the engine speed (e.g., rotational speed of output shaft 44) based on output from an engine speed sensor. At block 208, controller 36 detects the wheel or ground speed and CVT speed based on output from speed sensors 59 of FIG. 2. In one embodiment, a wheel speed sensor is coupled to and detects the rotational speed of output shaft 74 of sub-transmission 56 and/or an axle or wheel of final drive 58. In one embodiment, a CVT speed sensor detects the rotational speed of secondary clutch 52 (e.g., shaft 46 of FIG. 2) and/or primary clutch 50 of CVT 48.

[0043] At block 210, controller 36 compares the detected engine speed to an engine speed threshold. At block 214, controller 36 compares the detected wheel speed and/or CVT speed to respective speed thresholds. If the engine speed is less than or equal to the engine speed threshold at block 210 and if the wheel speed and CVT speed are less than or equal to the respective speed thresholds at block 214, controller 36 shifts sub-transmission 56 to the target gear configuration by outputting a control signal to actuator 57 at block 218. [0044] If the engine speed is greater than the engine speed threshold at block 210, controller 36 reduces the engine speed to at or below the threshold speed at block 212 prior to implementing the gear shift. In one embodiment, controller 36 reduces the engine speed by reducing the throttle valve opening of engine 42. If the wheel speed is greater than the wheel speed threshold at block 214, or if the CVT speed is greater than the CVT speed threshold at block 214, controller 36 at block 216 either denies the shift request immediately or waits a predetermined time delay for the wheel speed and/or CVT speeds to reduce to the respective speed threshold. In one embodiment, if the wheel speed and/or CVT speed do not reduce to the corresponding threshold prior to expiration of the predetermined time delay (e.g., 30 seconds), controller 36 denies the shift request (e.g., clears the shift request without implementing the request).

[0045] In one embodiment, the status of the gearshift is displayed on display 106 of FIG. 2. For example, display 106 flashes "Requested Gear" to provide an indication the gear shift has been requested but not implemented due to the engine speed and wheel/CVT speeds not meeting thresholds or other suitability checks not being satisfied. Display 106 also provides an indication when the gear shift has been executed and denied.

[0046] In one embodiment, the threshold engine speed of block 210 is based on the engagement speed at which clutch assembly 45 engages primary clutch 50 of CVT 48. For example, the threshold engine speed is set to a speed less than the clutch engagement speed described herein to ensure that engine 42 is decoupled from CVT 48 when the gear shift occurs. In another embodiment, the threshold engine speed of block 210 is based on the speed at which primary clutch 50 of CVT 48 engages belt 54. For example, in one embodiment, primary clutch 50 engages belt 54 in response to a speed of primary clutch 50 exceeding a belt engagement speed threshold. The threshold engine speed is set to a speed less than the belt engagement speed to ensure that primary clutch 50 is decoupled from belt 54 when the gear shift occurs. In one embodiment, the threshold wheel speed at block 214 is zero miles per hour (mph) or between zero and 5 mph. In one embodiment, the threshold CVT speed at block 214is zero or between zero and 50 rpm. Other suitable threshold speeds may be provided at blocks 210 and 214. [0047] In one embodiment, the method 200 of FIG. 4 allows controller 36 to verify that the engine speed, wheel speed, and CVT speed are at suitable levels before shifting sub-transmission 56 to reduce the likelihood of causing damage to the drive line of vehicle 10. For example, sub-transmission 56 is less likely to grind gears during a shift by waiting until the wheel speed and CVT speed are substantially zero prior to shifting. Similarly, by requiring the engine speed to be below the clutch engagement threshold speed, CVT 48 is decoupled from the output of engine 42 prior to shifting sub- transmission 56.

[0048] Referring to FIG. 5, a flow diagram 250 is illustrated of another exemplary operation performed by control system 40 of FIG. 2 for electronically shifting sub- transmission 56. The method of FIG. 5 illustratively controls a rolling shift (e.g., shift on the fly) such that sub-transmission 56 is shifted while vehicle 10 is moving. In one embodiment, a rolling shift is only allowed by controller 36 when shifting between forward gears (e.g., between high range and low range) or when shifting between neutral gear and forward or reverse gear, although other suitable shifting conditions may be provided for a rolling shift. Reference is made to FIG. 2 throughout the following description of FIG. 5.

[0049] At block 252, controller 36 detects a shift request initiated with shift device 55 that identifies a target gear configuration of sub-transmission 56. Controller 36 determines the current gear configuration of sub-transmission 56 at block 254 based on output from a position sensor (e.g., shift drum sensor 1 10 of FIG. 3). At block 256, controller 36 detects the engine speed. At block 258, controller 36 detects the speed of sub-transmission 56 and/or the wheel (ground) speed. At block 260, controller 36 determines the gear ratio of CVT 48 and a speed of CVT 48, illustratively the speed of output shaft 46 of FIG. 2. At block 262, controller 36 determines a target engine speed based on the current and target gear configurations of sub-transmission 56, the gear ratio of CVT 48, the output speed of CVT 48 (e.g., speed of output shaft 46 of secondary clutch 52), and the wheel speed and/or speed of sub-transmission 56. For example, controller 36 determines the target engine speed required to drive CVT 48 such that the speed of output shaft 46 of CVT 48 will match the speed of the input of sub-transmission 56 after sub-transmission 56 is shifted to the requested target gear. For example, the speeds of output shaft 46 and the input of sub-transmission 56 match when the rotational speeds are the same or are within a predefined range of each other, such as within 50 RPM, for example. Accordingly, the likelihood of grinding or damaging gears and other components of sub-transmission 56 during a rolling shift is reduced.

[0050] At block 264, controller 36 disengages sub-transmission 56 from CVT 48. In one embodiment, disengaging sub-transmission 56 includes shifting sub-transmission 56 to a neutral space or dead spot between gear positions. In another embodiment, sub-transmission 56 includes a clutch controlled by controller 36 to disengage sub- transmission 56 from CVT 48. At block 266, while sub-transmission 56 is disengaged, controller 36 adjusts the engine speed to match the target engine speed calculated at block 262 by electronically controlling throttle valve assembly 62 of FIG. 2. In the illustrated embodiment, the engine speed matches the target engine speed when the engine speed is the same as the target engine speed or is within a predetermined threshold range of the target engine speed, such as within 50 RPM, for example. When the engine speed sufficiently matches the target engine speed, and thereby the speed of output shaft 46 sufficiently matches the post-shift input speed of sub-transmission 56, controller 36 at block 268 shifts sub-transmission 56 to the target gear identified in the shift request and re-engages sub-transmission 56 to CVT 48. As described herein, controller 36 shifts sub-transmission 56 by outputting a shift command to actuator 57. In an embodiment with a clutch disengaging sub-transmission 56 from CVT 48, controller 36 drives engine 42 to the target speed before, during, or after shifting sub- transmission 56 to the target gear and before re-engaging sub-transmission 56 via the clutch.

[0051] Referring again to FIG. 2, controller 36 is further operative to lock out one or more gears of sub-transmission 56 in response to a detected operating condition and/or user input. For example, in one embodiment controller 36 selectively locks out gears of sub-transmission based on an operating mode selected by the user via mode selection device 64 of FIG. 2. For example, in some modes, such as plow mode, work mode, rock crawling mode, snow/ice mode, and/or learner mode, controller 36 locks out high range forward gear such that the user cannot select high range or such that an override input is required to select high range. An override input may include a code or other input via display 106 of FIG. 2.

[0052] In one embodiment, controller 36 locks out one or more gears, such as high range gear, in response to detecting a seat belt being disengaged and/or the operator leaving seat 18a (FIG. 1 ). Controller detects the loaded and unloaded state of seat 18a based on the force detected with seat sensor 66, as described herein. If vehicle 10 is being driven in high range gear when the disengaged seat belt or unloaded seat 18a is detected, controller 36 in one embodiment automatically shifts sub-transmission 56 into the low range gear and locks out high range until the seat belt is engaged and the seat 18a is in the loaded state. A suitable time delay (e.g., one to five seconds, etc.) may be implemented after detecting the unloaded seat or disengaged seat belt before automatically shifting into the low range gear. Controller 46 may further reduce or limit the throttle opening to a threshold opening upon detecting the unloaded seat or disengaged seat belt. In one embodiment, when sub-transmission 56 is in park or neutral while engine 42 is running, controller 36 locks out the forward and reverse gears until the seat belt is engaged and the operator is positioned in seat 18a. Other interlocks may be monitored in addition to the seat belt and seat 18a engagement, such as the engagement of side nets or doors of vehicle 10. In one embodiment, controller 36 locks out one or more gears of sub-transmission 56 by ignoring or not executing shift requests for the locked out gears. [0053] In one embodiment, controller 36 is operative to automatically shift sub- transmission 56 into park or neutral in response to vehicle 10 being turned off and the operator leaving seat 18a (FIG. 1 ). For example, in response to detecting the engine 42 or vehicle 10 shutting down and seat 18a being in an unloaded state, controller 36 automatically shifts sub-transmission 56 into park or neutral after a predetermined time delay (e.g., 30 seconds). In one embodiment, controller 36 automatically shifts sub- transmission 56 into park under these conditions only when vehicle 10 is positioned at an incline which exceeds a threshold inclination angle, as determined with inclinometers 70 of FIG. 2. As such, vehicle 10 may be less likely to roll down a hill when vehicle 10 is left unattended by an operator. In one embodiment, a user input may override the automatic park to allow vehicle 10 to be towed when engine 42 or vehicle 10 is shutdown. For example, controller 36 allows a user to shift sub-transmission 56 into neutral while engine 42 is shut down to disengage CVT 48 from final drive 58 for towing operations. [0054] In one embodiment, controller 36 automatically shifts sub-transmission 56 into park from a forward or reverse gear in response to all of the following conditions being met: engine 42 running at idle speed or below the clutch engagement speed, the wheel speed being zero, seat 18a being unoccupied for a threshold duration, and the incline of vehicle 10 exceeding the threshold inclination angle. [0055] In one embodiment, controller 36 is further operative to lock sub-transmission 56 in the park gear when vehicle 10 is shut down, either automatically as described herein or in response to a lockout request by a user (e.g., a code entered). When locked in park, controller 36 requires a set of conditions to be satisfied before allowing sub-transmission 56 to shift out of the park configuration. For example, controller 36 requires one or more of the following conditions to be met before shifting out of park: the presence of a key is detected in the ignition or near the ignition (via RFID or key fob), seat 18a is in the loaded state, the seat belt is engaged, and a brake interlock is satisfied. In one embodiment, controller 36 further requires engine 42 to be running to execute a shift request for shifting out of park. For the brake interlock, controller 36 detects an application of brake operator 68 of FIG. 2 based on feedback provided by the brake operator sensor (e.g., pressure sensor or position sensor). In this embodiment, controller 36 requires brake operator 68 to be engaged by the operator by a threshold pressure or displacement amount prior to shifting into park. [0056] In one embodiment, the conditions for unlocking or locking a particular gear are displayed on display 106. For example, the conditions for shifting sub-transmission 56 out of park are listed on display 106 to inform the operator what steps to take to shift out of park. Similarly, the interlocks and corresponding locked out gears are displayed on display 106, such as when the seat belt, doors, or side nets are disengaged and the seat is unoccupied.

[0057] In one embodiment, engine 42 is configured to operate in a power generation mode. The generated power output by engine 42 is used, for example, to power a hydraulic pump or generate electricity. Power generation mode is selectable via mode selection device 64 of FIG. 2. In the power generation mode, controller 36 shifts sub- transmission 56 into the neutral gear position to decouple the output of engine 42 and CVT 48 from the final drive 58. Controller 36 is operative to lock out other gear configurations of sub-transmission 56 during the power generation mode regardless of a shift request for a different gear configuration. [0058] Referring to FIG. 6, an exemplary shifter 55 of FIG. 2 is illustrated in the form of a shift handle or lever 29 positioned between seats 18a and 18b of vehicle 10 (FIG. 1 ). Shift handle 29 is configured to move in the forward (shift up) direction toward the front of vehicle 10 and the backward (shift down) direction toward the rear of vehicle to allow an operator to shift through the gear positions of sub-transmission 56. Shift handle 29 is coupled to a shift sensor for communicating the shifter position to controller 36. In one embodiment, the shift sensor includes a three-position, momentary ON-OFF- ON toggle switch 78 (see FIG. 2). Switch 78 is spring-biased to the middle OFF position, and moving shift handle 29 forward or backward causes contacts of switch 78 to engage an ON position to generate a corresponding shift request to controller 36. Accordingly, shift handle 29 is biased to the middle position illustrated in FIG. 6, and actuation of shift handle 29 forward or reverse initiates a shift request.

[0059] In the illustrated embodiment, the duration of input provided with shift handle 29 serves to request a different sub-transmission gear position. For example, shift handle 29 may be actuated for a short hold (short duration) or a long hold (long duration). A short hold is an actuation of the shift handle 29 to the forward or backward position held for less than a threshold duration, and a long hold is an actuation of shift handle 29 in the forward or backward position held for longer than the threshold duration. An exemplary threshold duration is 300 milliseconds (ms), 500 ms, or another suitable threshold duration programmed into controller 36. In one embodiment, the shift input provided by shift handle 29 is filtered by controller 36 to reduce the likelihood of shifting in response to an inadvertent shift request, such as a shift request resulting from an accidental bump to shift handle 29, for example. An exemplary filter includes controller 36 ignoring shifter actuations held for less than a second threshold duration, such as 100 ms, for example.

[0060] In the illustrated embodiment, a short hold on shift handle 29 in the forward or backward position allows for stepping through the gear range of sub-transmission 56. An exemplary gear range pattern is park - reverse - neutral - low range forward - high range forward (PRNLH). With sub-transmission 56 in the park gear position, actuation of shift handle 29 forward for a short duration requests reverse gear, a subsequent forward short hold actuation requests neutral gear, a subsequent forward short hold actuation requests low range, and a subsequent forward short hold actuation requests high range. Similarly, reverse short hold actuations on shift handle 29 result in stepping backward through the gear range of sub-transmission 56.

[0061] In one embodiment, a long hold on shift handle 29 provides for shifting directly to the end gear position of the gear range based on the direction shift handle 29 is actuated. For example, in the PRNLH gear pattern, when sub-transmission 56 is in park, reverse, neutral, or low range, a long hold actuation of shift handle 29 in the forward direction generates a shift request for the high range. Similarly, when sub- transmission 56 is in reverse, neutral, low range, or high range, a long hold actuation of shift handle 29 in the backward direction generates a shift request for the park position. [0062] In one embodiment, the long hold input with shift handle 29 is configured differently for different operating modes. For example, in the plow mode or work mode, a long hold on shift handle 29 in the forward or backward direction causes sub- transmission 56 to shift directly between low forward range and reverse gears, respectively. The configuration of the long hold input is selectable by an operator based on the operating mode selected with mode selection device 64 of FIG. 2. In one embodiment, the long hold input configuration is programmable into controller 36 via a user input (e.g., via buttons of display 106 or other input device) to identify which gears are selected in response to long hold actuations of shift handle 29. [0063] In another embodiment, shift handle 29 is moveable to a different detent position for each different gear of sub-transmission 56. Based on the position of shift handle 29, controller 36 shifts sub-transmission 56 to a different gear position. In the PRNLH gear range described above, shift handle 29 has five different detent positions each corresponding to one of park, reverse, neutral, low forward range, and high forward range.

[0064] In an alternative embodiment, shifter 55 of FIG. 2 is separated into right-hand and left-hand controls provided with two shift devices, such as paddles or buttons, coupled on or near steering wheel 28. For example, right- and left-hand shift devices 55 of FIG. 2 may be coupled to the right and left side of steering wheel 28 near position 130 of FIG. 6 inside the outer perimeter of steering wheel 28. Similarly, right- and left- hand shift devices 55 may be coupled to opposite sides of steering column 128 behind steering wheel 28. For example, the right-hand shift device 55 may be coupled to steering column 128 at position 132 of FIG. 6, and the left-hand shift device 55 may be coupled at a similar position on the opposite side of steering column 128. As such, an operator may shift through the gear range of sub-transmission 56 while keeping both hands positioned on steering wheel 28.

[0065] For a straddle-type vehicle (e.g., all-terrain vehicle or snowmobile), the hand shifters 55 are coupled to right and left sides of the handlebar near the location of an operator's hands. Referring to FIG. 8, an exemplary straddle seat vehicle 310 is illustrated that incorporates the control system 40 of FIG. 2 and described herein.

Straddle-type vehicle 310 includes a frame or chassis 315 that is supported above the ground surface by front and rear wheels 322. Vehicle 310 includes a straddle seat 318 positioned above an engine 342 and behind a steering device, illustratively a handlebar 328. Handlebar 328 includes a left grip 350 and a right grip 352. A left-hand shifter 55 (FIG. 2) is coupled to handlebar 328 at location 354, and a right-hand shifter 55 (FIG. 2) is coupled to handlebar 328 at location 356. Locations 354 and 356 are adjacent or near respective grips 350, 352 such that an operator may shift through the gear range of sub-transmission 56 (FIG. 2) while keeping both hands positioned on handlebar 328. Shifters 55 of straddle type vehicle 310 include paddles, buttons, or other suitable shift request devices.

[0066] In the embodiments of FIGS. 6 and 8 including right-hand and left-hand shift devices 55, each shift device 55 is coupled to a two position, ON-OFF momentary toggle switch biased in the OFF position. In one embodiment, each short hold actuation to the left-hand shift device 55 controls gear selections in the up direction (e.g., from park to high forward range), and each short hold actuation to the right-hand shift device 55 controls gear selections in the down direction (e.g., from high forward range to park), or vice versa. Similarly, a long hold actuation on right-hand or left-hand shift device 55 causes sub-transmission 56 to jump to a corresponding end of the gear range (e.g., high forward range for left hand device 55 and park for right-hand device 55) or to a configured particular gear based on the selected operating mode (e.g., shift directly between reverse and low forward range for work or plow mode).

[0067] In one embodiment, shifter 55 of FIG. 2 includes one or more additional input devices, such as buttons or toggle switches, configured to control an implement or attachment 86 (FIG. 2) or other accessory coupled to the vehicle and controlled by controller 36. Referring to FIG. 7, shift handle 29 includes a plurality of buttons 140 coupled to a head portion 142 of shift handle 29. Buttons 140 are thumb or finger actuated, for example, to provide user accessibility without requiring the user to remove a hand from shift handle 29. Buttons 140 are in communication with controller 36 and provide various functionalities based on the operating mode selected with mode selection device 64 of FIG. 2. For example, in a plow mode, buttons 140 allow an operator to control the position and orientation of a plow blade or scoop attached to the front of vehicle 10. In a work mode, buttons 140 provide input to controller 36 for controlling a winch coupled to vehicle 10, i.e., for controlling the winch motor to retract and extend the winch cable. Buttons 140 may also be used to start, stop, and otherwise control power generation provided with engine 42 (FIG. 2) in a power generation mode. A position, orientation, and operation of a snow blower attachment may also be controlled with buttons 140. Other suitable functionality may be provided with buttons 140 for controlling an attachment 86 of vehicle 10.

[0068] In another embodiment, vehicle 10 of FIG. 1 includes a hydrostatic transmission rather than the CVT 48 of FIG. 2. In another embodiment, vehicle 10 includes a sequential transmission rather than the CVT 48 and sub-transmission 56 of FIG. 2. In this embodiment, the sequential transmission is electronically shifted by controller 36 according to the control strategies described herein. An exemplary gear range pattern of a sequential transmission includes reverse gear - first gear - second gear - third gear - fourth gear - fifth gear (R12345), and each gear is electronically controlled by controller 36 based on shift requests from shifter 55 of FIG. 2 as described with respect to sub-transmission 56 of FIG. 2. The sequential transmission may have fewer or additional gears.

[0069] While vehicle 10 of FIG. 1 and vehicle 310 of FIG. 8 are described herein as including an engine 42 as the power source, vehicle 10, 310 may alternatively include an electric motor as the power source for powering the drivetrain. Vehicle 10, 310 may also comprise a hybrid vehicle having both an electric motor and an engine.

[0070] While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.