Direct drive power system for working vehicles with torque control mode

Abstract

The present invention discloses a power system, comprising: an engine; a sensor for determining an engine speed; and a transmission device. The transmission device comprises: an input element, the input element being configured to receive power from the engine as an input torque; an output element, the output element being configured to provide at least a portion of the power from the engine as an output torque; and a clutch device, the clutch device converting the input torque into an output torque. The clutch device comprises at least one clutch, the at least one clutch being selectively positionable between a fully engaged state, a partially engaged state, and a fully disengaged state, wherein in the partially engaged state, a portion of the input torque is converted into an output torque. The controller is coupled to the at least one clutch and is configured to generate a clutch command based at least in part on the engine speed to position the at least one clutch to a fully engaged state, a partially engaged state, or a fully disengaged state.

Description

Technical Field

[0001] The present invention relates generally to work vehicles and, more particularly, to regulating output torque in a work vehicle. Background Art

[0002] Heavy work vehicles, such as those used in the construction, agricultural and forestry industries, typically include a powertrain having an internal combustion engine in the form of a compression ignition engine (i.e., a diesel engine) or a spark ignition engine (i.e., a gasoline engine). Many work vehicles (e.g., motor graders) have a direct drive transmission (or direct drive mode) in which the output of the engine is directly coupled to the wheels of the work vehicle. In such an arrangement, it is desirable to improve the regulation of torque through the driveline. Summary of the invention

[0003] The invention provides a power system for adjusting the output torque of a working vehicle.

[0004] In one aspect, the present invention provides a power system for providing power to a driven component of a work vehicle. The power system includes: an engine configured to generate power; a sensor configured to determine an engine speed associated with the engine; and a transmission. The transmission includes: an input element configured to receive power from the engine as an input torque; an output element configured to provide at least a portion of the power from the engine to the driven component as an output torque; and a clutch device coupled to the input element and the output element to convert the input torque into an output torque. The clutch device includes at least one clutch, the at least one clutch selectively positionable between a fully engaged state, a partially engaged state, and a fully disengaged state, wherein in the fully engaged state, substantially all of the input torque is converted into the output torque, in the partially engaged state, a portion of the input torque is converted into the output torque as a resultant torque fraction, and in the fully disengaged state, no input torque is converted into the output torque. The power system includes a controller coupled to receive data of the engine speed from the sensor. The controller is also coupled to the at least one clutch and is configured to generate a clutch command based at least in part on the engine speed to position the at least one clutch into a fully engaged state, a partially engaged state, or a fully disengaged state.

[0005] In another aspect, the present invention provides a transmission controller for a transmission of a work vehicle, the transmission having a clutch device to convert input torque from an engine into output torque to drive a transmission system. The transmission controller includes a processor and a memory, the memory storing one or more computer programs executable by the processor to perform transmission control operations. The transmission control operations include: receiving a default mode selection for implementing a default mode or a torque control mode selection for implementing a torque control mode; receiving data of an engine speed of the engine; and when implementing the torque control mode, generating a clutch command for the clutch device based on the engine speed so as to place at least one clutch of the clutch device in a fully engaged state, a partially engaged state, or a fully disengaged state, in which substantially all of the input torque is converted into output torque, in which partially engaged state, a portion of the input torque is converted into output torque as a synthetic torque fraction, and in which fully disengaged state, no input torque is converted into output torque.

[0006] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a side view of an exemplary work vehicle in the form of a motor grader in which a power system may be implemented in accordance with the present disclosure;

[0008] Figure 2 According to an exemplary embodiment Figure 1 A schematic block diagram of a power system of a working vehicle;

[0009] Figure 3 According to an exemplary embodiment Figure 2 A schematic diagram of an exemplary transmission device of a power system;

[0010] Figure 4 is an implementation according to an exemplary embodiment Figure 2 a graphical representation of a resultant torque fraction as a function of engine speed in a torque control mode of a powertrain system of; and

[0011] Figure 5 According to a further embodiment of the exemplary embodiment Figure 2 A graphical representation of the resultant torque fraction as a function of time during a braking event in a torque control mode of the powertrain system.

[0012] Like reference numbers in the various drawings represent like elements. DETAILED DESCRIPTION

[0013] One or more exemplary embodiments of the disclosed system and method for regulating output torque in a work vehicle are described below, as illustrated in the figures of the drawings briefly described above. Various modifications to the exemplary embodiments may occur to those skilled in the art.

[0014] As used herein, unless otherwise limited or modified, a list of elements separated by a connective term (e.g., "and") and preceded by the phrase "one or more of" or "at least one of" indicates a configuration or arrangement that may include the listed elements individually or in any combination. For example, "at least one of A, B, and C" or "one or more of A, B, and C" indicates the possibility of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

[0015] Typically, a work vehicle may include a powertrain having an engine to produce torque in a wide range of applications, such as motor graders, long-haul trucks, tractors, agricultural or construction vehicles, surface mining equipment, non-electric locomotives, stationary generators, etc. In some work vehicles, the engine is directly mechanically coupled to a vehicle driven component, such as a propulsion wheel or a drive wheel, via a direct-drive transmission.

[0016] As used herein, a "direct mechanical" power transmission or "direct drive" transmission may include the transmission of mechanical power by a direct physical connection, by various integrally formed components, or via various intermediate mechanical elements (e.g., gear sets) to change the speed. In contrast, for example, a power transmission using a torque converter or other fluid coupling device may not be considered a "direct mechanical" transmission. As used herein, "between" may refer to a position relative to the power flow, rather than an actual physical position. Thus, for example, if power is transmitted from the engine through a clutch device to reach the output element, the clutch device may be considered to be located "between" the engine and the output element power conversion device.

[0017] In some embodiments, a vehicle or transmission controller selectively operates in a torque control mode in which a clutch command is generated to convert an input torque to an output torque as a function of engine speed. In particular, at relatively low engine speeds, the controller generates a clutch command to place the clutch of the transmission clutch device in a partially engaged state to generate a resultant torque fraction of the output torque that is less than the input torque. The manner in which the controller increases and decreases the resultant torque fraction in response to engine speed can vary based on the gear selection and braking characteristics. In effect, the torque control mode can enhance control of the transmission so that the engine can be operated at relatively high speeds that avoid stalling, even while being able to achieve a relatively slower output and reduced output torque at the wheels than would otherwise be possible given the gear ratio of the transmission.

[0018] One or more exemplary embodiments of the disclosed systems and methods for improving the operation of a powertrain system, particularly with respect to operating a direct drive transmission, are described below. Discussion herein may sometimes focus on an exemplary application of a transmission arrangement in a motor grader, but the disclosed systems and methods may be applied to other types of work vehicles and / or other types of engines and transmission systems.

[0019] refer to Figure 1 In some embodiments, the disclosed systems and methods may be used with a work vehicle 100 having a power system 102 that is selectively operable in a torque control mode in which torque may be additionally mitigated within the power system 102. In general, various functions of the power system 102 and / or the work vehicle 100, including the torque control mode, may be implemented using a controller 104, which will be discussed in greater detail below after a brief introduction to the work vehicle 100. Although not shown or described in detail herein, the work vehicle 100 may include any number of additional or alternative systems, subsystems, and elements.

[0020] In this example, work vehicle 100 is a road or motor grader ("grader") having a chassis 106 that supports a power system 102 that generates power to propel or move work vehicle 100, as well as to provide power for various work functions of work vehicle 100. Power system 102 includes a plurality of axles 108, each supporting one or more wheels 110, and a prime mover (e.g., "engine") 112, which typically generates power in the form of output torque via a transmission 114 to drive one or more of axles 108 and wheels 110. Work vehicle 100 may have any number of axles 108 and associated drive wheels 110, including first, second, and third axles 108 and corresponding wheels 110. Power system 102 may drive some or all of wheels 110 (e.g., only rear wheels, both front and rear wheels, etc.) based on the configuration of transmission 114 and associated drive components. Although the described embodiment includes wheels 110, any suitable output element or mechanism for engaging a support surface (e.g., the ground) may be provided, including tires, continuous tracks, or other traction devices. In some examples, the engine 112, transmission 114, and wheels 110 may be considered part of a drive train. Additionally, brakes 116 may be provided to stop or slow the rotation of the wheels 110 and the overall movement of the vehicle 100.

[0021] The work vehicle 100 also includes an implement 118 for performing one or more work functions. In this example, the implement 118 is a ground engaging tool having a blade located between the second axle and the third axle 108, which scrapes and flattens the supporting surface during the grading operation. The implement 118 may include alternative or additional implements, such as a tiller, a scarifier, a front attachment, a plow, a sweeper, a shovel, etc., and may also be positioned in a variety of positions. The implement 118 may be driven by power from the power system 102 to perform various types of actuation based on commands from the controller 104 or other suitable mechanism.

[0022] Returning to the powertrain 102, the engine 112 is any power source that provides rotational driveline power, including input power to the transmission 114 for subsequent transfer of power as output torque to the wheels 110. For example, the engine 112 may include, but is not limited to, an internal combustion engine, a piston engine, a rotary engine, a hydraulic motor, a hydrostatic system, an electric motor, etc. The term "engine" as used herein is not limited to any particular type of prime mover.

[0023] Broadly speaking, the transmission 114 may be implemented as a single speed or multi-speed transmission, or an infinitely variable transmission via a direct coupling, a torque converter drive, a hydrostatic drive, an electric motor drive, or any other transmission known now or in the future to those of ordinary skill in the art. As an example, a direct drive multi-speed transmission may be provided, wherein the transmission 114 is coupled to the wheels 110 via a direct physical connection, via various integrally formed components, or via various intermediate mechanical elements (e.g., a gear set) to vary the rotational speed. In general, the embodiments of the powertrain 102 discussed herein may be applied to any powertrain system that includes friction elements or any other powertrain system that is capable of varying the level of torque application.

[0024] In this example and as discussed in more detail below, the transmission 114 may include an input side element 120 and an output side element 122 coupled with various elements capable of transmitting torque via a clutch device 124. The input side element 120 receives power from the engine 112 as input torque, and the clutch device 124 converts the input torque into an output torque on the output side element 122. For example, the output torque from the output side 122 is directly geared to and drives one or more of the wheels 110.

[0025] Typically, the clutch device 124 includes one or more clutches, each having a cooperating element that is configured to engage with each other in a frictional manner to transmit at least a portion of the torque through the corresponding clutch, and is configured to separate from each other to cut off the transmission of the torque through the corresponding clutch. In one example, each clutch of the clutch device 124 can be associated with a pressure or proportional control valve that receives or releases pressure based on a command from the controller 104 to reposition the corresponding clutch element. For example, the controller 104 generates a clutch command to the control valve in the form of a controlled current so that the clutch pressure is adjusted in a manner proportional to the current. It should be understood that the clutch engagement can be controlled in other suitable ways.

[0026] In this way, the controller 104 can command the clutch to change the engagement level to represent the selected clutch state. In one example, the clutch state can include: a fully engaged state, in which the two clutch elements are fully engaged to transmit torque through the corresponding clutch practically or approximately in full; a fully disengaged state, in which the two clutch elements are fully disengaged to not transmit torque through the corresponding clutch; and a partially engaged state, in which the two clutch elements are partially engaged to transmit a portion of the torque through the clutch. The partially engaged state corresponds to a range of engagement or clutch pressures between less than fully engaged and greater than disengaged. The fully engaged state and the partially engaged state can be considered to be "actuated" states. As used herein, with respect to the fully engaged state, the term "transmitting torque practically or approximately in full" means that the output torque is equal to the input torque, subject to normal efficiency losses through the transmission, for example, so that the output torque is higher than 90% or 95% of the input torque. As described in more detail below, the controller 104 can command a selected amount of pressure to a single clutch or combination of clutches to transfer a desired amount of torque between the input side element 120 and the output side element 122, and thus between the engine 112 and the axle 108 or wheels 110, thereby enabling the magnitude of the output torque to be adjusted. Additional information regarding the operation of the clutch device 124 will be provided in more detail below.

[0027] The vehicle 100 may additionally include a cab 126 for housing an operator, and various components that facilitate the operator's operation of the vehicle 100, including a throttle 128, a gear selection element 130, a brake input element 132, a mode selection element 134, and a display device 136. Generally, the throttle 128 may receive input from the operator indicating a speed or power request. In the case of a gear change, an increase in the throttle position generally increases the speed of the engine 112, while a decrease in the throttle position generally decreases the speed of the engine 112. The gear selection element 130 receives input from the operator indicating a gear or speed ratio selection ("gear selection") of the transmission 114. In some examples, the gear selection element 130 may be omitted and / or the gear selection may be automated by the controller 104. The brake input element 132 receives input from the operator indicating a request to decelerate or stop the wheels 110 of the vehicle 100 with the brakes 116.

[0028] The mode selection element 134 can receive an operator input indicating a selected mode associated with the power system 102. In one example, the operation of the power system 102 can be considered to include a first or default mode and a torque control mode, but other modes can also be provided. Generally, and as discussed in more detail below, in the default mode, the controller 104 selectively commands the clutch of the clutch device 124 of the transmission 114 to enter an engaged state and a disengaged state; in the torque control mode, the controller 104 selectively commands the clutch of the clutch device 124 of the transmission 114 to enter an engaged state, a disengaged state, and a partially engaged state, thereby enabling additional control of torque through the transmission 114.

[0029] Typically, the throttle 128, the gear selection element 130, the brake input element 132, and the mode selection element 134 can take any suitable form, including a lever, a button, a knob, a graphical user interface element incorporated into a display device, a switch, a pedal, a joystick, a keyboard, an audio device, a microphone associated with a voice recognition system, or various other human-machine interface devices. The display device 136 can also take any form, such as a monitor, which is operably connected to the controller 104 for providing visual feedback to the operator. In one embodiment, the display device 136 is provided as a simple flat screen display tablet in the operator's cab 126. In other embodiments, the display device 136 is a head-up type display, wherein an image is projected or otherwise displayed on a window of, for example, the operator's cab 126. Typically, the display device 136 can display or otherwise communicate the selected power system mode and other information associated with the power system 102 to the operator, as discussed in more detail below. In some examples, one or more of the throttle 128 , the gear selection element 130 , the brake input element 132 , and / or the display device 136 may be omitted and / or associated functions may be automated.

[0030] The vehicle 100 may also include one or more sensors to collect information associated with the vehicle 100. In one example, the sensor may include an engine speed sensor 138 that measures the engine speed at the engine output shaft (not shown) or the transmission input side element 120, typically in the form of revolutions per minute (RPM). Other sensors may be provided. For example, in some embodiments, a temperature sensor associated with the clutch device 124 and / or the transmission 114 may be provided.

[0031] As described above, controller 104 is provided to control various operational aspects of work vehicle 100. Generally, controller 104 may receive inputs from a plurality of sources, including an operator, via throttle 128, gear selection element 130, brake input element 132, and mode selection element 134, as well as inputs from various sensors, units, and systems onboard or remote from the vehicle; and in response, controller 104 generates one or more types of commands executed by various systems of vehicle 100. As one example discussed in greater detail below, controller 104 may facilitate operation of powertrain 102, particularly with respect to implementing a default mode and a torque control mode to regulate torque through transmission 114. In addition, controller 104 may generate display signals associated with such operation on display device 136.

[0032] Broadly, the controller 104 may be configured as a computing device with an associated processor device and memory architecture, a hardwired computing circuit (or circuits), a programmable circuit, a hydraulic, electrical or electro-hydraulic controller, or other. In this way, the controller 104 may be configured to perform various computing and control functions with respect to the work vehicle 100 (or other machinery). In some embodiments, the controller 104 may be configured to receive input signals in various formats (e.g., as hydraulic signals, voltage signals, current signals, etc.), and output command signals in various formats (e.g., as hydraulic signals, voltage signals, current signals, mechanical movements, etc.). In some embodiments, the controller 104 (or a portion thereof) may be configured as an assembly of hydraulic components (e.g., valves, flow lines, pistons and cylinders, etc.), so that control of various devices (e.g., pumps or motors) may be implemented using, and may be implemented based on, hydraulic, mechanical or other signals and movements.

[0033] As described above and discussed in more detail below, the powertrain 102 may have a default mode and a torque control mode in which the controller 104 generates a clutch command for the clutch device 124 to regulate the output torque to the wheels 110. In the torque control mode, the commanded clutch pressure within the transmission 114 causes only a portion of the torque to be transmitted through the clutch device 124 of the transmission 114, resulting in a reduced output torque at the output element being transmitted to the drive wheels 110. Reference will be made to Figure 2 The operation of the powertrain system 102 , particularly operation during the torque control mode, is discussed in greater detail.

[0034] Reference Figure 2 , showing the Figure 11 is a schematic diagram of a powertrain 102 for powering a vehicle 100, with data flows indicating exemplary operations. In general, the controller 104 may be implemented as a processor 140 and a memory 142, wherein the processor 140 implements the various functions of the powertrain 102 described herein by running programs or instructions stored in the memory 142. In addition, the memory 142 may be considered to include a database or other type of data storage device for storing system parameters and / or schedules in response to evaluating data inputs and generating commands, as discussed in more detail below. The controller 104 may be considered a vehicle controller or a dedicated transmission controller to implement the operation of the transmission 114 during various modes.

[0035] As shown, the controller 104 receives various inputs including a mode selection from a mode selection element 134, a power request from an accelerator 128, a gear selection from a gear selection element 130, and a brake request from a brake input element 132. The controller 104 also receives data related to the engine speed from an engine speed sensor 138.

[0036] Regardless of the mode, the controller 104 generates an engine command for the engine 112 based on the power request and generates a brake command for the brake 116 based on the brake request. In response, the engine 112 implements the engine command and the brake 116 implements the brake command. Although not shown and / or discussed in greater detail, the controller 104 may also receive operator input associated with the implement 118 and generate associated implement commands to perform various work functions. Such commands may be based on lookup tables and / or instructions stored in the memory 142.

[0037] Initially, the controller 104 determines the current mode in view of the mode selection and modifies the mode if the mode selection is different from the current mode or maintains the mode if the mode selection matches the current mode. As described above, the mode selection may correspond to a default mode or a torque control mode. The operation of the transmission 114 during the default mode and the torque control mode will now be described.

[0038] During the default mode, the controller 104 generates a clutch command for the clutch device 124 corresponding to the gear selection. The controller 104 may generate the clutch command (e.g., as a specific current for the clutch control valve) based on a default mode schedule stored as a lookup table in the memory 142 or other suitable mechanism. Figure 3As described in more detail with reference to the exemplary clutch arrangement 124 shown in FIG, the clutch commands generated by the controller 104 are used to actuate selected clutches within the clutch arrangement 124 and / or to maintain other selected clutches as non-actuated (or disengaged) to implement a specific gear ratio between the engine 112 and the wheels 110. Notably, in a default mode, the actuated clutch of the clutch arrangement is placed in a fully engaged state so that substantially all of the torque from the engine 112 is transferred to the wheels 110 through the engaged clutch.

[0039] Brief reference Figure 3 , which is a relatively simple example of a clutch device 124 that can implement the default mode (and torque control mode, as described below) of the powertrain system 102 described herein. Figure 3 In the example of the embodiment of the present invention, the clutch device 124 is positioned between the input side element 120 in the form of an input shaft 150 and the output side element 122 in the form of an output shaft 154, wherein the input gear element 152 is attached to the input side element and the output gear element 156 is attached to the output side element. The clutch device 124 shown further includes a first clutch 158, a second clutch 160, a third clutch 162, and a fourth clutch 164 connected together via a coupling shaft 166. The first clutch 158 and the third clutch 162 are selectively engaged with the input gear element 152, and the second clutch 160 and the fourth clutch 164 are selectively engaged with the output gear element 156. Thus, in this example, the engine 112 is connected by a mechanical power transmission connection (e.g., a rotating shaft, various gears, clutches, etc.), rather than by a torque converter or power conversion device, but other examples may have different configurations. Thus, when the combination of clutches 158, 160, 162, 164 is engaged, as described below, a direct mechanical connection can be established between the engine 112 and the wheels 110. It should be appreciated that various other transmission types or configurations may be employed in addition (or alternatively) to this example and other examples.

[0040] As described above, the controller 104 generates clutch commands to actuate one or more of the clutches 158, 160, 162, 164 to achieve various gear ratios (or "gears") between the input shaft 150 and the output shaft 154. For example, in the default mode, in the first gear, the first clutch 158 and the second clutch 160 are placed in a fully engaged state, while the third clutch 162 and the fourth clutch 164 are in a fully disengaged state; in the second gear, the second clutch 160 and the third clutch 162 are placed in a fully engaged state, while the first clutch 158 and the fourth clutch 164 are in a fully disengaged state; in the third gear, the first clutch 158 and the fourth clutch 164 are in a fully engaged state, while the second clutch 160 and the third clutch 162 are in a fully disengaged state; in the fourth gear, the third clutch 162 and the fourth clutch 164 are in a fully engaged state, while the first clutch 158 and the second clutch 160 are in a fully disengaged state. In this way, the controller 104 can modify the transmission ratio from the engine 112 to the wheels 110 according to the gear selection from the input side element 120. As described above, in this default mode, the actuated clutches 158, 160, 162, 164 are fully engaged and no clutch is commanded to a partially engaged state.

[0041] Reference again Figure 2 , upon receiving a mode selection indicating a torque control mode, the controller 104 initiates the power system 102 to operate in the torque control mode. Typically, the controller 104 generates a clutch command based on a torque control mode schedule, which can be stored in the memory 142 as a lookup table. As in the default mode, the controller 104 generates a clutch command for the clutch device 124, which corresponds to the gear selection from the input side element 120. In addition, the controller 104 additionally generates a clutch command as a function of the engine speed during the torque control mode, and can place the selected clutch in a partially engaged state, a fully engaged state, or a fully disengaged state. In particular, contrary to the default mode, the controller 104 in the torque control mode also utilizes the partial engagement state of the clutch to modify the output torque through the clutch device 124. In fact, during the torque control mode, the degree of actuation of the actuated clutch is based on the engine speed, so that at certain speeds, the actuated clutch is commanded to enter a specific partially engaged state, and at other speeds, the actuated clutch is commanded to enter a fully engaged state. In this manner, each clutch in the partially engaged state experiences individual slip to effectively reduce the potential efficiency of the clutch relative to the fully engaged state such that only a portion of the torque is transferred through the transmission.

[0042] Reference again Figure 3, except that each actuated clutch 158, 160, 162, 164 of the clutch device 124 can be actuated to a fully engaged state or a partially engaged state, the actuation or non-actuation of the clutches 158, 160, 162, 164 in the torque control mode generally corresponds to the actuation or non-actuation in the default mode. In particular, for the torque control mode, in the first gear, the first clutch 158 and the second clutch 160 are actuated to a fully or partially engaged state, while the third clutch 162 and the fourth clutch 164 are in a fully disengaged state; in the second gear, the second clutch 160 and the third clutch 162 are actuated to a fully or partially engaged state, while the first clutch 158 and the fourth clutch 164 are in a fully disengaged state; in the third gear, the first clutch 158 and the fourth clutch 164 are actuated to a fully or partially engaged state, while the second clutch 160 and the third clutch 162 are in a fully disengaged state; and in the fourth gear, the third clutch 162 and the fourth clutch 164 are actuated to a fully or partially engaged state, while the first clutch 158 and the second clutch 160 are in a fully disengaged state. In summary, in the torque control mode, the clutches 158, 160, 162, 164 that are not disengaged can be actuated to a partially or fully engaged state to control torque through the transmission 114.

[0043] The degree of actuation of each clutch 158, 160, 162, 164 within the partially engaged state or into the fully engaged state may be based on engine speed according to a predetermined torque control mode schedule of clutch current corresponding to clutch pressure (e.g., "effective clutch pressure") to produce a predetermined torque fraction (e.g., "combined torque fraction") of torque of the actuated clutches 158, 160, 162, 164 relative to full engagement of the clutch arrangement 124. In general, the term combined torque fraction may refer to a portion of the torque converted by the combination of the actuated clutches 158, 160, 162, 164 of the clutch arrangement 124. In some examples, only one of the actuated clutches 158, 160, 162, 164 may be partially engaged to generate a combined torque fraction of less than 100%. In other words, only a single partially engaged clutch 158, 160, 162, 164 can implement a modified torque output so that the amount of torque not transmitted through the partially engaged clutch 158, 160, 162, 164 also corresponds to the amount of torque not transmitted through the clutch device 124. In other examples, a combination of clutches 158, 160, 162, 164 can be partially engaged to generate a composite torque fraction of less than 100%. In other words, two or more partially engaged clutches 158, 160, 162, 164 can generate a composite torque fraction of less than 100% in a combined manner. Therefore, in the following discussion, the "effective clutch pressure" that generates the composite torque fraction can be achieved in a single clutch 158, 160, 162, 164 or a combination of actuated clutches 158, 160, 162, 164. In any case, the composite torque fraction can be a function of the engine speed and other parameters (such as the selected gear).

[0044] Figure 4 An exemplary torque control mode chart 180 is shown in FIG. 1 , which shows the resultant torque fraction given the engine speed on the horizontal axis 184 and the corresponding effective clutch pressure on the vertical axis 182. In particular, the torque control mode schedule 180 may have a lookup table of stored clutch commands in the form of current as a function of engine speed (and optional gear selection) to achieve the generation of Figure 4 . For example, a 50% combined torque fraction indicates that one or more of the actuated clutches in the clutch device 124 for a particular gear selection are actuated to a partially engaged state (or states) such that the output torque of the clutch device 124 is approximately 50% of the input torque.

[0045] The nature of the relationship between engine speed and resultant torque fraction may vary based on the gear selected. For example, Figure 4The torque control mode schedule 180 includes a first schedule portion 185 corresponding to the first gear, a second schedule portion 186 corresponding to the second gear, a third schedule portion 187 corresponding to the third gear, and a fourth schedule portion 188 corresponding to the fourth gear.

[0046] In first gear, and refer to Figure 3 1, the controller 104 generates clutch commands for actuating the first clutch 158 and the second clutch 160. As reflected by the first schedule portion 185, the controller 104 places the first clutch 158 and / or the second clutch 160 in a partially engaged state so that the resulting torque fraction through the transmission 114 is approximately 10% at engine speeds less than 800 rpm. Between 800 rpm and approximately 1200 rpm, the resulting torque fraction increases from approximately 10% to approximately 60% at a first rate proportional to the engine speed; and between approximately 1200 rpm and approximately 1250 rpm, the resulting torque fraction increases from approximately 60% to approximately 100% at a second rate proportional to the engine speed. Therefore, when the engine speed is between 1200 rpm and 1250 rpm, the resulting torque fraction is more sensitive to the engine speed (e.g., increases at a greater rate). Above 1250 rpm, the resultant torque fraction is 100%, indicating that the first clutch 158 and the second clutch 158 are in a fully engaged state and all torque is transferred between the input shaft 150 and the output shaft 154 through the actuated clutches 158 , 160 .

[0047] In the second gear, the controller 104 generates a clutch command to actuate the second clutch 160 and the third clutch 162. As reflected in the second schedule portion 186, the controller 104 places the second clutch 160 and the third clutch 162 in a partially engaged state so that the resulting torque fraction through the transmission 114 is approximately 10% at engine speeds less than 800 rpm. Between approximately 800 rpm and 900 rpm, the resulting torque fraction increases from approximately 10% to approximately 25% at a first rate proportional to the engine speed; between approximately 900 rpm and 1100 rpm, the resulting torque fraction increases from approximately 25% to approximately 65% ​​at a second rate proportional to the engine speed; and between approximately 1100 rpm and 1200 rpm, the resulting torque fraction increases from approximately 65% ​​to approximately 100% at a third rate proportional to the engine speed. Thus, the resulting torque fraction in the second gear is generally more sensitive to engine speed (e.g., increases at a greater rate) than in the first gear. Above 1200 rpm, the resultant torque fraction is 100%, indicating that the second clutch 160 and the third clutch 162 are in a fully engaged state and all torque is transferred between the input shaft 150 and the output shaft 154 through the actuated clutches 160 , 162 .

[0048] In third gear, the controller 104 generates a clutch command to actuate the first and fourth clutches 158, 164. As reflected in the third schedule portion 187, the controller 104 places the first clutch 158 and the fourth clutch 164 in a partially engaged state so that the resulting torque fraction through the transmission 114 is approximately 20% at engine speeds less than 800 rpm. Between approximately 800 rpm and 900 rpm, the resulting torque fraction increases from approximately 20% to approximately 30% at a first rate proportional to the engine speed; between approximately 900 rpm and 1200 rpm, the resulting torque fraction increases from approximately 30% to approximately 100% at a second rate proportional to the engine speed. Therefore, the resulting torque fraction in third gear is generally more sensitive to engine speed (e.g., increases at a greater rate) than in first and second gears. Above 1200 rpm, the resultant torque fraction is 100%, indicating that the first clutch 158 and the fourth clutch 164 are in a fully engaged state and all torque is transferred between the input shaft 150 and the output shaft 154 through the actuated clutches 158 , 164 .

[0049] In fourth gear, the controller 104 generates a clutch command to actuate the third clutch 162 and the fourth clutch 164. As reflected in the fourth schedule portion 188, the controller 104 places the third clutch 162 and the fourth clutch 164 in a partially engaged state so that the resulting torque fraction through the transmission 114 is approximately 20% at engine speeds less than 800 rpm. Between approximately 800 rpm and 900 rpm, the resulting torque fraction increases from approximately 20% to approximately 40% at a first rate proportional to the engine speed; between approximately 900 rpm and 1100 rpm, the resulting torque fraction increases from approximately 40% to approximately 100% at a second rate proportional to the engine speed. Therefore, the resulting torque fraction in fourth gear is generally more sensitive to engine speed (e.g., increases at a greater rate) than in first, second, and third gears. Above 1100 rpm, the resultant torque fraction is 100%, indicating that the third clutch 162 and the fourth clutch 164 are in a fully engaged state and all torque is transferred between the input shaft 150 and the output shaft 154 through the actuated clutches 162 , 164 .

[0050] In one embodiment, and with additional reference to Figure 2 , the controller 104 may generate a display signal for the display device 136 that describes information about the operation of the powertrain system 102, including the current powertrain system mode, the resultant torque fraction, the current gear, and / or the current engine speed. Other parameters and characteristics may be described.

[0051] In some embodiments, the controller 104 may additionally consider “braking events” (eg, receiving a braking request from the brake input element 132 and generating a braking command for the brakes 116 ) to implement the torque control mode. Figure 5 Another example of a torque control mode schedule 190 is shown in FIG. 1 , which shows the resultant torque fraction of the corresponding effective clutch pressure on the vertical axis 192 for time on the horizontal axis 194 during a braking event. In particular, the torque control mode schedule 190 may have a stored lookup table of clutch commands in the form of current to enable generation of Figure 5 The effective clutch pressure of the resultant torque fraction shown in . The nature of the relationship between the resultant torque fraction and time during and after a braking event may vary based on the selected gear. For example, Figure 5 The torque control mode schedule 190 includes a first schedule portion 195 corresponding to the first gear, a second schedule portion 196 corresponding to the second gear, a third schedule portion 197 corresponding to the third gear, and a fourth schedule portion 198 corresponding to the fourth gear. Figure 5 In the example of , a braking event (eg, a braking request from the brake input element 132 ) is reflected at a time of 1 second.

[0052] In the absence of a braking event, the torque control mode schedule 190 may approximate any suitable torque control mode schedule, such as Figure 4 The torque control mode schedule 180 is shown. Figure 5 The torque control mode schedule 190 of FIG. 1 reflects the effect of a braking event on the resultant torque fraction. At the time of a braking event, the controller 104 commands a clutch pressure that provides a resultant torque fraction of approximately 5% in all gears. The total value of the resultant torque fraction caused by the braking event can be considered the minimum resultant torque fraction. At a time of 2 seconds, the controller 104 increases the resultant torque fraction at one or more slopes based on the selected gear to meet (or "return" to) the resultant torque fraction of the torque control mode schedule (e.g., schedule 180) based on engine speed without a braking event. As reflected in the first schedule portion 195, the controller 104 increases the resultant torque fraction to approximately 100% in the first gear within a time of 5 seconds. As reflected in the second schedule portion 196 and the third schedule portion 197, the controller 104 increases the resultant torque fraction to approximately 100% in the second and third gears within a time of 4 seconds, although at different slopes. As reflected in the fourth schedule portion 198 , the controller 104 increases the resultant torque fraction to approximately 100% over a period of 3.5 seconds in fourth gear.

[0053] As mentioned above, despite Figure 5 The schedule portions 185-188 of FIG. 1 show the resultant torque fraction returning to 100%, but in one example, the schedule portions 185-188 may return to an appropriate value of the resultant torque fraction based on the engine speed, such as by Figure 4 180 is reflected in the list. For example, consider Figure 4 and 5 List 180, 190, when the engine speed is above 1200 rpm during a braking event, Figure 5 The schedule 190 will be implemented as shown for all gears. However, at lower engine speeds during a braking event, Figure 4 The resultant torque fraction is Figure 5 The resultant torque fraction of schedule 190 is further modified, for example, at a time of 3 seconds after a braking event at an engine speed of 900 rpm in fourth gear, the resultant torque fraction is approximately 24% (e.g., when controller 104 returns to the 40% resultant torque fraction of schedule 180, it is 60% resultant torque fraction after the braking event of schedule 190). In this way, controller 104 enables transmission 114 to operate in a torque control mode during a braking event in order to decelerate vehicle 100 in response to the braking command without decelerating engine speed.

[0054] In one embodiment, and with additional reference to Figure 2 , controller 104 may generate a display signal for display device 136 that describes information about the operation of powertrain system 102 during a braking event, including an indication of the braking event, current mode, resultant torque fraction, current gear, and / or current engine speed. Other parameters and characteristics may be provided.

[0055] although Figure 4 and Figure 5 Exemplary torque control mode schedules 180, 190 and schedule portions 185-188, 195-198 are shown, but various features may vary in any suitable manner. For example, the variation of the resultant torque fraction may be non-linear and / or consistent between different gears.

[0056] As described above, one or more temperature sensors may be provided to collect temperature information associated with the clutch device 124 and / or the transmission 114, particularly during torque control modes where a partially engaged clutch may generate heat. In some embodiments, this temperature information may be considered as part of a mechanism for protecting the clutch device.

[0057] Thus, embodiments discussed herein provide a vehicle or transmission controller that selectively operates in a torque control mode in which a clutch command is generated based on engine speed to convert input torque into output torque. In particular, at relatively low engine speeds, the controller generates a clutch command to place a clutch of a clutch device of the transmission in a partially engaged state to generate a resultant torque fraction of output torque that is less than the input torque. The manner in which the controller increases and decreases the resultant torque fraction based on engine speed can vary based on gear selection and braking characteristics. In effect, the torque control mode can enhance control of the transmission such that the engine can be operated at relatively high speeds to avoid stalling, even while being able to achieve a relatively slower output and reduced output torque at the wheels than would otherwise be possible given the gear ratio of the transmission.

[0058] Among other benefits, the exemplary embodiments can provide a direct drive transmission configuration with a combination of control and efficiency, but without the need for a torque converter or other fluid coupling between the engine and various other components of the powertrain. The disclosed powertrain features can be advantageously used in a variety of settings and with a variety of machines.

[0059] As will be appreciated by those skilled in the art, certain aspects of the disclosed subject matter may be embodied as a method, a system (e.g., a work vehicle control method implemented as a series of steps by a controller of a work vehicle), or a computer program product. Thus, certain embodiments may be implemented entirely as hardware, entirely as software (including firmware, resident software, microcode, etc.), or as a combination of software and hardware (and other) aspects. Furthermore, certain embodiments may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium.

[0060] Embodiments of the present disclosure may be described herein in terms of functional and / or logical block components and various processing steps. It should be understood that such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform specified functions. For example, embodiments of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and the work vehicles and control systems and methods described herein are merely exemplary embodiments of the present disclosure.

[0061] For the sake of brevity, conventional techniques related to other functional aspects of work vehicle and engine operation, control, and systems (and individual operating components of the systems) may not be described in detail herein. In addition, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and / or physical connections between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0062] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, and other functional aspects of the system (and the various operating components of the system) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent exemplary functional relationships and / or physical connections between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0063] The controller may be on-board, remote, or a combination thereof, and may also be considered a vehicle controller, an exhaust treatment system controller, and / or one or more dedicated controllers for the components discussed herein. Typically, the controller may include any suitable type of processor and memory, the memory containing instructions that can be executed by the processor to implement the various functions described herein. The controller may be configured as a hardwired computing circuit (or multiple circuits), a programmable circuit, a hydraulic controller, an electric controller, an electro-hydraulic controller, or other. Thus, the controller may be configured to perform various computational and control functions with respect to the exhaust treatment system. In some embodiments, the controller may be configured to receive input signals in various formats (e.g., as hydraulic signals, voltage signals, current signals, etc.) and output command signals in various formats (e.g., as hydraulic signals, voltage signals, current signals, mechanical motion, etc.).

[0064] Any suitable computer-usable or computer-readable medium may be utilized. The computer-usable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-usable or computer-readable storage medium (including storage devices associated with a computing device or a client electronic device) may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or apparatus, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable media would include the following: an electrical connection with one or more conductors, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device. In the context of this document, a computer-usable or computer-readable storage medium may be any tangible medium that may contain or store a program used by or in conjunction with an instruction execution system, device or apparatus.

[0065] A computer readable signal medium may include, for example, a data signal propagated in baseband or as part of a carrier wave, wherein the propagated data signal has computer readable program code embodied therein. Such a propagated signal may take any of a variety of forms, including but not limited to electromagnetic, optical, or any suitable combination thereof. A computer readable signal medium may be non-transitory and may be any computer readable medium that is not a computer readable storage medium and that can convey, propagate, or transmit a program used by or in conjunction with an instruction execution system, apparatus, or device.

[0066] Any flow chart and block diagram in the accompanying drawings or similar discussion above can illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each box in the flow chart or block diagram can represent a module, segment or part of a code, which includes one or more executable instructions for realizing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box (or described in addition herein) may not occur in the order marked in the figure. For example, depending on the function involved, the two boxes shown in succession (or the two operations described in succession) can actually be performed substantially simultaneously, or these boxes (or operations) can sometimes be performed in reverse order. It will also be noted that each box of any block diagram and / or flow chart illustration and the combination of boxes in any block diagram and / or flow chart illustration can be realized by a system based on special hardware or a combination of special hardware and computer instructions that performs a specified function or action.

[0067] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", and "the or described" are intended to also include plural forms unless the context clearly indicates otherwise. It will also be understood that the terms "comprise" and / or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0068] In addition, the following examples are provided, which are numbered for easier reference.

[0069] 1. A power system for providing power to a driven component of a work vehicle, comprising: an engine configured to generate power; a sensor configured to determine an engine speed associated with the engine; a transmission device, the transmission device including an input element, an output element, and a clutch device, the input element being configured to receive power from the engine as an input torque, the output element being configured to provide at least a portion of the power from the engine to the driven component as an output torque, the clutch device being coupled to the input element and the output element to convert the input torque into an output torque, the clutch device including at least one clutch selectively positionable between a fully engaged state, a partially engaged state, and a fully disengaged state, wherein in the fully engaged state, substantially all of the input torque is converted into the output torque, in the partially engaged state, a portion of the input torque is converted into the output torque as a resultant torque fraction, and in the fully disengaged state, no input torque is converted into the output torque; and a controller coupled to receive data of the engine speed from the sensor, the controller also being coupled to the at least one clutch and being configured to generate a clutch command based at least in part on the engine speed to position the at least one clutch into the fully engaged state, the partially engaged state, or the fully disengaged state.

[0070] 2. A power system according to Example 1, wherein the transmission is a direct drive transmission.

[0071] 3. A power system according to Example 1, wherein the controller is configured to selectively operate according to a default mode schedule in a default mode and according to a torque control mode schedule in a torque control mode; wherein the at least one clutch includes a plurality of clutches, the plurality of clutches including: at least one first clutch, which is configured to convert the input torque into the output torque at a first gear ratio as a first gear when actuated by the clutch command; and at least one second clutch, which is configured to convert the input torque into the output torque at a second gear ratio as a second gear when actuated by the clutch command; and wherein the controller is configured to generate a clutch command in the first gear of the torque control mode according to a first schedule portion of the torque control mode schedule, and the controller is configured to generate a clutch command in the second gear of the torque control mode according to a second schedule portion of the torque control mode schedule associated with the second gear, the first schedule portion being different from the second schedule portion.

[0072] 4. A power system according to Example 3, wherein the controller is configured to generate the clutch command in the first gear of the default mode to actuate the at least one first clutch to the fully engaged state; wherein the controller is configured to generate the clutch command in the second gear of the default mode to actuate the at least one second clutch to the fully engaged state; wherein the controller is configured to generate the clutch command in the first gear of the torque control mode based on the engine speed in accordance with the first schedule of the torque control mode schedule to actuate the at least one first clutch between the partially engaged state and the fully engaged state; and wherein the controller is configured to generate the clutch command in the second gear of the torque control mode based on the engine speed in accordance with the second schedule of the torque control mode schedule to actuate the at least one second clutch between the partially engaged state and the fully engaged state.

[0073] 5. A power system according to Example 4, wherein the controller is configured to generate a clutch command in a first gear of a torque control mode to place at least one first clutch in a partially engaged state when the engine speed is lower than a first predetermined engine speed, and to place at least one first clutch in a fully engaged state when the engine speed is greater than the first predetermined engine speed; and wherein the controller is configured to generate a clutch command in a second gear of a torque control mode to place at least one second clutch in a partially engaged state when the engine speed is lower than a second predetermined engine speed, and to place at least one second clutch in a fully engaged state when the engine speed is greater than the second predetermined engine speed.

[0074] 6. A power system according to Example 5, wherein the controller is configured to generate a clutch command in a first gear of a torque control mode to place at least one first clutch in a partially engaged state when the engine speed is lower than a first predetermined engine speed, thereby converting an input torque into an output torque with a composite torque fraction less than the input torque; and wherein the controller is configured to generate a clutch command in a second gear of the torque control mode to place at least one second clutch in a partially engaged state when the engine speed is lower than a second predetermined engine speed, thereby converting the input torque into an output torque with a composite torque fraction less than the input torque.

[0075] 7. The power system of Example 6, wherein the first predetermined engine speed is different from the second predetermined engine speed.

[0076] 8. A power system according to Example 6, wherein the at least one first clutch includes at least a first clutch and a second clutch; and wherein the controller is configured to generate a clutch command in a first gear of a torque control mode to place one of a first clutch or a second clutch of at least one first clutch in a partially engaged state when the engine speed is lower than a first predetermined engine speed, thereby converting the input torque into an output torque with a synthetic torque fraction less than the input torque.

[0077] 9. A power system according to Example 6, wherein the at least one first clutch includes at least a first clutch and a second clutch; and wherein the controller is configured to generate a clutch command in a first gear of a torque control mode to place both the first clutch and the second clutch of at least one first clutch in a partially engaged state when the engine speed is lower than a first predetermined engine speed, thereby jointly converting the input torque into an output torque with a synthetic torque fraction less than the input torque.

[0078] 10. A power system according to Example 6, wherein the controller is connected to receive a braking request and generate a braking command for at least one brake of the work vehicle; and wherein the controller is configured to generate a clutch command when a braking request is received in a first gear of a torque control mode to place at least one first clutch in a partially engaged state so that the combined torque output fraction is a minimum combined torque fraction.

[0079] 11. A power system according to Example 10, wherein the controller is configured to generate a clutch command in the first gear of the torque control mode when a braking request is completed to place at least one first clutch in a partially engaged state so that the combined torque fraction increases at a slope to a combined torque fraction that partially matches the first schedule of the torque control mode schedule.

[0080] 12. The power system of Example 3, wherein the controller is configured to receive a mode selection from an operator mode selection element to implement the default mode or the torque control mode.

[0081] 13. A transmission controller for a transmission of a work vehicle, the transmission having a clutch device to convert input torque from an engine into output torque to drive a transmission system, the transmission controller comprising: a processor; and a memory storing one or more computer programs executable by the processor to perform transmission control operations, the transmission control operations comprising: receiving a default mode selection for implementing a default mode or a torque control mode selection for implementing a torque control mode; receiving data of an engine speed of the engine; and when implementing the torque control mode, generating a clutch command for the clutch device based on the engine speed so as to place at least one clutch of the clutch device in a fully engaged state, a partially engaged state, or a fully disengaged state, in which substantially all of the input torque is converted into output torque, in which partially engaged state a portion of the input torque is converted into output torque as a composite torque fraction, and in which no input torque is converted into output torque.

[0082] 14. A transmission controller according to Example 13, wherein the transmission control operation also includes selectively operating according to a default mode schedule in a default mode and according to a torque control mode schedule in a torque control mode, so that in a first gear of the torque control mode, the clutch command is generated according to a first schedule portion of the torque control mode schedule, and in a second gear of the torque control mode, the clutch command is generated according to a second schedule portion of the torque control mode schedule associated with the second gear, and the first schedule portion is different from the second schedule portion.

[0083] 15. A transmission controller according to Example 14, wherein the transmission control operation also includes selectively performing the following operations: operating in the first gear of the default mode so that the clutch command is generated to actuate at least one first clutch to the fully engaged state; operating in the second gear of the default mode so that the clutch command is generated to actuate at least one second clutch to the fully engaged state; operating in the first gear of the torque control mode so that the clutch command is generated based on the engine speed in accordance with the first schedule of the torque control mode schedule to actuate the at least one first clutch between the partially engaged state and the fully engaged state; and operating in the second gear of the torque control mode so that the clutch command is generated based on the engine speed in accordance with the second schedule of the torque control mode schedule to actuate at least one second clutch between the partially engaged state and the fully engaged state.

[0084] The description of the present disclosure has been presented for the purpose of illustration and description, but it is not intended to be exhaustive or limited to the disclosure of the disclosed form. Without departing from the scope and spirit of the present disclosure, many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments explicitly cited herein are selected and described to best explain the principles of the present disclosure and its practical application, and to enable other persons of ordinary skill in the art to understand the present disclosure and recognize many substitutions, modifications and variations to the described (one or more) examples. Therefore, various embodiments and embodiments other than those explicitly described are within the scope of the appended claims.

Claims

1. A power system for providing power to a driven component of a work vehicle, comprising: an engine configured to generate power; a sensor configured to determine an engine speed associated with the engine; A transmission device, the transmission device comprising: an input element configured to receive power from the engine as input torque; an output element configured to provide at least a portion of the power from the engine to the driven component as output torque; and a clutch device coupled to the input element and the output element to convert the input torque into the output torque, the clutch device including at least one clutch selectively positionable between a fully engaged state in which substantially all of the input torque is converted into the output torque, a partially engaged state in which a portion of the input torque is converted into the output torque as a resultant torque fraction, and a fully disengaged state in which no input torque is converted into the output torque; and a controller coupled to receive data of the engine speed from the sensor, the controller also coupled to the at least one clutch and configured to generate a clutch command based at least in part on the engine speed to position the at least one clutch into the fully engaged state, the partially engaged state, or the fully disengaged state; Wherein the at least one clutch comprises a plurality of clutches, the plurality of clutches comprising: at least one first clutch configured to convert the input torque to the output torque at a first gear ratio as a first gear when actuated by the clutch command; and at least one second clutch configured to convert the input torque to the output torque at a second gear ratio as a second gear when actuated by the clutch command; wherein the at least one first clutch comprises at least a first clutch and a second clutch; and The controller is configured to generate the clutch command to place both the first clutch and the second clutch of the at least one first clutch in the partially engaged state when the engine speed is below a first predetermined engine speed, thereby jointly converting the input torque into the output torque at the resultant torque fraction that is less than the input torque.

2. The power system according to claim 1, wherein: The transmission is a direct drive transmission.

3. The power system according to claim 1, wherein the controller is configured to selectively operate in a default mode according to a default mode schedule and in a torque control mode according to a torque control mode schedule; and The controller is configured to generate the clutch command in the first gear of the torque control mode according to a first schedule portion of the torque control mode schedule, and is configured to generate the clutch command in the second gear of the torque control mode according to a second schedule portion of the torque control mode schedule associated with the second gear, the first schedule portion being different from the second schedule portion.

4. The power system according to claim 3, wherein the controller is configured to generate the clutch command in the first gear of the default mode to actuate both the first clutch and the second clutch of the at least one first clutch into the fully engaged state; wherein the controller is configured to generate the clutch command in the second gear of the default mode to actuate the at least one second clutch into the fully engaged state; as well as The controller is configured to generate the clutch command based on the engine speed in part according to the second schedule of the torque control mode schedule in the second gear of the torque control mode to actuate the at least one second clutch between the partially engaged state and the fully engaged state.

5. The power system according to claim 4, in, The controller is configured to generate the clutch command in the second gear of the torque control mode to place the at least one second clutch in the partially engaged state when the engine speed is less than a second predetermined engine speed to convert the input torque into the output torque at the resultant torque fraction that is less than the input torque.

6. The power system according to claim 5, wherein: The first predetermined engine speed is different than the second predetermined engine speed.

7. The power system according to claim 5, wherein the controller is coupled to receive a braking request and generate a braking command for at least one brake of the work vehicle; and The controller is configured to generate the clutch command upon receiving the braking request in the first gear of the torque control mode to place the first clutch or the second clutch of the at least one first clutch in the partially engaged state so that the resultant torque fraction is a minimum resultant torque fraction.

8. The power system according to claim 7, wherein: The controller is configured to generate the clutch command to place the first clutch or the second clutch of the at least one first clutch in the partially engaged state when the braking request is completed in the first gear of the torque control mode, so that the combined torque fraction increases at a slope to a combined torque fraction that is partially consistent with the first schedule of the torque control mode schedule.

9. The power system according to claim 3, wherein: The controller is configured to receive a mode selection from an operator mode selection element to implement the default mode or the torque control mode.

10. A transmission controller for a transmission of a work vehicle, the transmission having a clutch device for converting input torque from an engine into output torque to drive a drive train, the transmission controller comprising: processor; as well as a memory storing one or more computer programs executable by the processor to perform transmission control operations, the transmission control operations comprising: receiving a default mode selection for implementing a default mode or a torque control mode selection for implementing a torque control mode; receiving data of an engine speed of the engine; and generating a clutch command for the clutch device based on the engine speed to place at least one clutch of the clutch device in a fully engaged state, a partially engaged state, or a fully disengaged state when the torque control mode is implemented, wherein substantially all of the input torque is converted into the output torque, a portion of the input torque is converted into the output torque as a resultant torque fraction, or a fully disengaged state, wherein no input torque is converted into the output torque; Wherein the at least one clutch comprises a plurality of clutches, the plurality of clutches comprising: at least one first clutch configured to convert the input torque to the output torque at a first gear ratio as a first gear when actuated by the clutch command; and at least one second clutch configured to convert the input torque to the output torque at a second gear ratio as a second gear when actuated by the clutch command; wherein the at least one first clutch comprises at least a first clutch and a second clutch; and wherein the transmission controller is configured to generate the clutch command to place both the first clutch and the second clutch of the at least one first clutch in the partially engaged state when the engine speed is below a first predetermined engine speed, thereby jointly converting the input torque into the output torque at the resultant torque fraction that is less than the input torque.

11. The transmission controller according to claim 10, wherein: The transmission control operation also includes selectively operating according to a default mode schedule in a default mode and according to the torque control mode schedule in the torque control mode so that in the first gear of the torque control mode, the clutch command is generated according to a first schedule portion of the torque control mode schedule, and in the second gear of the torque control mode, the clutch command is generated according to a second schedule portion of the torque control mode schedule associated with the second gear, the first schedule portion being different from the second schedule portion.

12. The transmission controller according to claim 11, wherein: The transmission device control operation also includes selectively performing the following operations: operating in the first gear of the default mode such that the clutch command is generated to actuate the first clutch and the second clutch of the at least one first clutch into the fully engaged state; operating in the second gear of the default mode such that the clutch command is generated to actuate the at least one second clutch into the fully engaged state; as well as Operating in the second gear of the torque control mode such that the clutch command is generated based in part on the engine speed according to the second schedule of the torque control mode schedule to actuate the at least one second clutch between the partially engaged state and the fully engaged state.

13. The transmission controller according to claim 12, wherein: The transmission device control operation also includes selectively performing the following operations: Operating in the second gear of the torque control mode, the clutch command is generated to place the at least one second clutch in the partially engaged state when the engine speed is less than a second predetermined engine speed, and to place the at least one second clutch in the fully engaged state when the engine speed is greater than the second predetermined engine speed.

14. The transmission controller according to claim 13, wherein: The transmission device control operation also includes selectively performing the following operations: Operating in the second gear of the torque control mode, the clutch command is generated to place the at least one second clutch in the partially engaged state when the engine speed is less than the second predetermined engine speed, thereby converting the input torque into the output torque at the resultant torque fraction that is less than the input torque.

15. The transmission controller according to claim 14, wherein: The transmission control operation also includes selectively operating such that the first predetermined engine speed is different from the second predetermined engine speed.

16. The transmission controller of claim 14, wherein: The transmission control operation also includes selectively operating to receive a braking request and generate a braking command for at least one brake of the work vehicle, and generating the clutch command when the braking request is received in the first gear of the torque control mode to place the first clutch or the second clutch of the at least one first clutch in the partially engaged state so that the combined torque fraction is a minimum combined torque fraction.

17. The transmission controller of claim 16, wherein: The transmission control operation also includes operating in the first gear of the torque control mode to generate the clutch command to place the first clutch or the second clutch of the at least one first clutch in the partially engaged state when the braking request is completed, so that the combined torque fraction increases at a slope to a combined torque fraction that is consistent with the first schedule portion of the torque control mode schedule.

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