Control systems and controllers for work vehicles

Abstract

This disclosure relates to a control system and controller for a work vehicle. A control system for a work vehicle includes: a power source comprising an engine configured to generate power and at least one electric motor; a transmission comprising a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and at least one electric motor along a power flow path to drive an output shaft of a powertrain; and a controller coupled to the power source and the transmission. The controller has a processor memory architecture configured to: monitor the electric motor speed of the at least one electric motor; and when the electric motor speed is less than a first predetermined stall speed threshold, generate and execute a clutch modulation command for the transmission, such that at least one clutch portion of the plurality of clutches along the power flow path engages.

Description

Technical Field

[0001] This disclosure generally relates to control systems for work vehicles, and more specifically, to power control systems for transmissions and electric motors of work vehicles. Background Technology

[0002] In the agriculture, construction, and forestry industries, work vehicles, including wheel loaders, can perform a wide variety of tasks. Modern work vehicles can utilize power from multiple power sources to provide useful power, including both conventional engines (e.g., internal combustion engines) and one or more continuously variable power sources (CVPs) (e.g., electric motors). In various applications, the work vehicle's powertrain can selectively utilize power provided by either an infinitely variable transmission (IVT) or a continuously variable transmission (CVT), either from only one power source or in combination. Furthermore, each mode can have one or more transmission (or speed) ratios when the clutch is selectively engaged and disengaged to change the power flow path. Certain operating conditions can pose challenges to certain modes using one or both types of power sources. Summary of the Invention

[0003] This disclosure provides a power control system for a work vehicle.

[0004] In one aspect, this disclosure provides a control system for a work vehicle. The system includes: a power source comprising an engine configured to generate power and at least one electric motor; a transmission comprising a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and the at least one electric motor along a power flow path to drive the output shaft of the work vehicle's powertrain; and a controller coupled to the power source and the transmission. The controller has a processor-memory architecture configured to: monitor the electric motor speed of the at least one electric motor; and when the electric motor speed is less than a first predetermined stall speed threshold, generate and execute a clutch modulation command for the transmission, such that at least one clutch among the plurality of clutches along the power flow path partially engages.

[0005] On the other hand, this disclosure provides a controller for a work vehicle having: an engine configured to generate power and at least one electric motor; and a transmission having a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and the at least one electric motor along a power flow path to drive an output shaft. The controller includes a processor memory architecture configured to: monitor the motor speed of the at least one electric motor; and when the motor speed is less than a first predetermined stall speed threshold, generate and execute a clutch modulation command for the transmission, such that at least one clutch portion of the plurality of clutches along the power flow path engages.

[0006] In other respects, this disclosure provides a method for operating a powertrain of a work vehicle, the powertrain comprising: an engine configured to generate power and at least one electric motor; and a transmission having a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and the at least one electric motor along a power flow path to drive an output shaft. The method includes: monitoring the electric motor speed of the at least one electric motor with a controller; and when the electric motor speed is less than a first predetermined stall speed threshold, generating and executing a clutch modulation command for the transmission at the controller, such that at least one clutch portion of the plurality of clutches along the power flow path engages.

[0007] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the specification, drawings, and claims. Attached Figure Description

[0008] Figure 1 This is a side view of an example work vehicle using a power control system with clutch modulation function to prevent electric motor stall according to an exemplary embodiment of this disclosure.

[0009] Figure 2 This is for implementation according to the example implementation method. Figure 1 The example is a powertrain with clutch modulation function in the power control system of a work vehicle.

[0010] Figure 3 This is a data flow diagram of a controller for implementing the clutch modulation function of a power control system according to an example embodiment;

[0011] Figure 4AThis is a data representation of the motor torque capability based on the motor speed, according to an example embodiment, which provides an example of considerations during clutch modulation function operation; and

[0012] Figure 4B This is a data representation of various parameters when the clutch modulation function is not in operation.

[0013] In the various figures, similar reference numerals indicate similar elements. Detailed Implementation

[0014] The following describes one or more exemplary embodiments of the disclosed powertrain control system, powertrain, or vehicle, as illustrated in the accompanying drawings of the figures briefly described above. Various modifications of the exemplary embodiments will be conceived by those skilled in the art.

[0015] Typically, work vehicles, such as those used in agriculture, construction, and forestry, can include a powertrain-based power control system. This powertrain has an engine and one or more additional power sources, such as one or more electric motors, which independently work together via a transmission to drive the vehicle and perform its work functions. For example, the power control system can implement: one or more split-path modes where power from the engine and electric motors is combined in the transmission to provide output torque; one or more direct-drive modes where only power from the engine provides output torque; and one or more series modes where power primarily from the electric motors provides output torque. Such a transmission can be considered a hybrid transmission, a continuously variable transmission (IVT), or an electric continuously variable transmission (eIVT); and such a powertrain can be considered a hybrid, IVT, or eIVT powertrain. In each mode, the transmission's clutch can be operated to provide one or more gear ratios or speed ratios.

[0016] During typical operation, the power control system can withstand relatively heavy loads, including loads that could bring the work vehicle to a stop and decelerate, despite the applied torque. In certain modes, particularly in series mode (e.g., where the output torque is provided by one or more electric motors), a decrease in vehicle speed can cause the motors to slow down to a value below their stall speed. Typically, after reaching the stall speed, the controller can reduce the motor's rated power to avoid thermal management issues. Thus, in these situations, the motors may not be able to provide the desired torque to the work vehicle, potentially impacting vehicle performance and efficiency.

[0017] However, according to this disclosure, the powertrain control system is configured to implement a clutch modulation function under certain conditions to appropriately address the potential effects of decelerating the electric motor. In one example, the conditions associated with the clutch modulation function may include the current mode of the transmission and / or the current electric motor speed. Specifically, the clutch modulation function can be implemented when the transmission mode is in series mode and when the current electric motor speed is approaching, below, or at the electric motor stall speed. After implementation, the electric motor control system can generate commands to modulate at least one clutch in the transmission, particularly one of the clutches in the power flow path of the transmission that connects the electric motor to the output shaft. In one example, the powertrain control system can achieve clutch modulation by churning the selected clutch (e.g., a rapid increase and decrease in the combined pressure at the clutch), while in other examples, the powertrain control system can achieve clutch modulation by targeting the combined pressure at the clutch for intermediate or partial engagement. The clutch modulation function is used to partially disengage the electric motor from the transmission, allowing the electric motor to obtain and / or maintain a speed higher than the electric motor stall speed, and avoiding or mitigating the resulting reduction in rated power, thereby maintaining the torque capability of the electric motor. Therefore, this invention enables a power control system with a motor stall prevention clutch modulation function, thereby providing consistent and reliable performance and efficiency, particularly in situations where it is not necessary to use a large-sized motor for high-torque, low-speed applications. Additional details are provided below.

[0018] Reference Figure 1 The work vehicle 100 may include or otherwise implement a power control system 102, which performs a clutch modulation function to ensure appropriate electric motor speed and torque capability, thereby providing consistent and smooth operation of the work vehicle 100. Figure 1 The view generally depicts the work vehicle 100 as a tractor. However, it should be understood that other configurations are possible in the agricultural, construction, and / or forestry industries, including configurations as wheel loaders. It should be further understood that the disclosed powertrain 106 can also be used for non-work vehicle and non-vehicle applications (e.g., stationary power units). In one example, the power control system 102 can be considered to include a controller 104, the powertrain 106, and one or more sensors 110 supported on the chassis 112 of the work vehicle 100, or otherwise interacting with the controller 104, the powertrain 106, and the sensors 110.

[0019] Typically, the powertrain 106 includes one or more power sources, such as an engine 114 (e.g., a diesel engine) and / or one or more continuously variable power sources (CVPs) 116a, 116b. Typically, CVPs 116a, 116b are electric motors and will be described below as such. However, in other embodiments, CVPs 116a, 116b may be other continuously variable power sources such as hydraulic motors. The electric motors 116a, 116b may be associated with, or otherwise incorporated into, one or more power components that regulate, store, and / or convert power out of and / or into the electric motors 116a, 116b. Such power components may include one or more sensors, controllers, batteries, and / or inverters (e.g., semiconductor devices with insulated-gate bipolar transistors (IGBTs)). As described above, if not addressed, a decrease in the speed of the motors 116a and 116b (particularly the motor 116b coupled to selectively drive the transmission 118) can lead to a reduction in torque capability, thus preventing thermal problems in the IGBT. The clutch modulation function is used to identify and resolve these conditions, thereby preventing improper heating of the power components, a reduction in the rated power of the motors 116a and 116b (e.g., a decrease in torque capability), and ensuring consistent and efficient operation of the powertrain 106, as described in more detail below.

[0020] The powertrain 106 also includes a transmission 118 that transmits power from power sources 114, 116a, 116b to a suitable power drive system coupled to one or more driven wheels (or tracks) 120 to enable the work vehicle 100 to propel itself. The wheels 120 interact directly with the support surfaces and are responsible for the movement and traction of the vehicle 100. The transmission 118 can also supply power to drive other vehicle systems, components, or implements. The transmission 118 may include various gears, shafts, clutches, and other power transmission elements that can operate within a range representing selected output speeds and / or torques. As described in more detail below, the power control system 102 enables clutch modulation functionality under one or more conditions within the powertrain 106.

[0021] Typically, controller 104 implements the operation of powertrain control system 102, powertrain 106, and other aspects of vehicle 100, including any functions described herein. Controller 104 can be configured as a computing device with an associated processor device memory architecture as a hydraulic, electric, or electrohydraulic controller or otherwise. Thus, controller 104 can be configured to perform various computational and control functions relative to vehicle 100. Controller 104 can communicate electronically, hydraulically, or otherwise with various other systems or devices of vehicle 100, including via a CAN bus (not shown). For example, controller 104 can communicate electronically or hydraulically with various actuators, sensors, and other devices within (or outside) vehicle 100.

[0022] In some implementations, controller 104 may be configured to receive input commands and interact with an operator via a human-machine interface or operator interface 122, including typical steering, acceleration, rate, transmission, and wheel braking control, as well as other suitable controls. Operator interface 122 may be configured in various ways and may include one or more joysticks, various switches or levers, one or more buttons, a touchscreen interface that may be overlaid on a display, a keyboard, a speaker, a microphone associated with a voice recognition system, or various other human-machine interface devices. Controller 104 may also receive input from one or more sensors 110 associated with various systems and components of the work vehicle 100, as discussed in more detail below. Additionally, as discussed below, controller 104 may implement powertrain control system 102 based on these inputs to generate appropriate commands for powertrain 106, particularly commands concerning clutch modulation functions.

[0023] As described above, the work vehicle 100 may include one or more sensors (typically represented by sensor 110) that communicate with the controller 104 to provide various types of feedback and data to enable the functions described herein and typical functions of the work vehicle 100. In some applications, sensor 110 may be provided to observe various conditions associated with the work vehicle 100. In one example, sensor 110 may provide information associated with the powertrain control system 102 to enable clutch modulation functions. Sensor 110 may include motion sensors that collect information associated with the position and / or movement of the work vehicle 100, such as one or more orientation sensors and / or one or more ground speed sensors. Additional sensors (or other sources or data) may provide or include sources of powertrain data, including data sufficient to determine the current or intended mode of the transmission 118, information associated with the position and state of one or more transmission clutch elements, and torque and / or speed information associated with the elements of the electric motors 116a, 116b, engine 114, and / or transmission 118. Specifically, sensor 110 can collect information related to current motor speed, clutch element speed, transmission output speed, ground speed, etc., for example, information that is collected directly or derived from other parameters.

[0024] As described in more detail below, the powertrain control system 102 is used to implement a clutch modulation function to prevent electric motor stall. The clutch modulation function is particularly useful in hybrid powertrain systems (e.g., systems with both an electric motor and an engine power source). See below for reference. Figure 2 An example powertrain 106 is described and discussed as an implementation aspect of the power control system 102. Subsequently, reference is made to... Figure 3 Additional details are provided regarding the power control system 102 that enables clutch modulation.

[0025] Reference Figure 2 As described above, the powertrain control system 102 can be considered to include a powertrain 106 and a controller 104, the controller 104 communicating with various components of the powertrain 106 and additionally with various vehicle systems and / or sensors 110. Figure 1) Receive information. Additionally, as described above, the powertrain 106 may include one or more power sources 114, 116a, 116b. Specifically, the powertrain 106 may include an engine 114, which may be an internal combustion engine of various known configurations; furthermore, the powertrain 106 may also include a first electric motor 116a and a second electric motor 116b connected together via conduits and / or other power components 116c. The powertrain 106 includes a transmission 118 that transmits power from the engine 114, the first electric motor 116a, and / or the electric motor 116b to the output shaft 230. As described below, the transmission 118 includes multiple gear sets, clutches, and control components to appropriately drive the output shaft 230 at different speeds in multiple directions. Typically, in one example, the transmission 118 of the powertrain 106 for implementing the powertrain control system 102 can be any type of continuously variable transmission (CVT) arrangement.

[0026] Engine 114 can, based on desired operation and commands from controller 104, provide rotational power to engine shaft 130 via an engine output element such as a flywheel. Engine shaft 130 can be configured to provide rotational power to gear 132. Gear 132 can mesh with gear 134, which can be supported on (e.g., fixed to) shaft 136. Shaft 136 can be substantially parallel to and spaced from engine shaft 130. Shaft 136 can support various components of powertrain 106, as will be discussed in detail.

[0027] Gear 132 may also mesh with gear 138 supported on shaft 140 (e.g., fixed to shaft 136). Shaft 140 may be substantially parallel to and separated from engine shaft 130, and shaft 140 may be connected to first electric motor 116a. Thus, mechanical power from the engine (i.e., engine power) can be transmitted via engine shaft 130 to the meshing gears 132, 138, to shaft 140, and to first electric motor 116a. Electric motor 116a can convert this power into an alternative form (e.g., electrical power) for transmission via conduit 116c to second electric motor 116b. This converted power can then be converted again by second electric motor 116b for mechanical output along shaft 142. Various control devices (not shown) described above may be provided to regulate this conversion, transmission, and re-conversion. Additionally, in some embodiments, shaft 142 may support gear 144 (or other similar components). Gear 144 can mesh with gear 146 and transmit power to gear 146. Gear 144 can also mesh with gear 148 and transmit power to gear 148. Therefore, power from the second electric motor 116b can be distributed between gears 146 and 148 for transmission to other components, as will be discussed in more detail below. The powertrain 106 may also include a variator 150, which represents an example of an arrangement that enables a continuously variable transmission (CVT) between the engine 114 and the electric motors 116a, 116b and the output shaft 230. As discussed below, this arrangement also enables a power control system 102, in which mechanical energy from the engine 114 can be used to boost electrical power in series mode. Other arrangements of the variator 150, engine 114, and electric motors 116a, 116b may be provided.

[0028] In some embodiments, the converter 150 may include at least two planetary gear sets. In some embodiments, the planetary gear sets may be interconnected and supported on a common shaft such as shaft 136, and planetary gear sets 152, 160 may be substantially concentric. In other embodiments, different planetary gear sets 152, 160 may be supported on separate, respective non-concentric shafts. The arrangement of the planetary gear sets can be configured based on the available space within the work vehicle 100 for enclosing the powertrain 106.

[0029] like Figure 2As shown in the embodiment, the transducer 150 may include a first planetary gear set (i.e., a "low" planetary gear set) 152 having a first sun gear 154, a first planetary gear and an associated carrier 156, and a first ring gear 158. Furthermore, the transducer 150 may include a second planetary gear set (i.e., a "high" planetary gear set) 160 having a second sun gear 162, a second planetary gear and an associated carrier 164, and a second ring gear 166. The second planetary gear and carrier 164 may be directly attached to the first ring gear 158. Additionally, the second planetary gear and carrier 164 may be directly attached to a shaft 168 on which a gear 170 is fixed. Furthermore, the second ring gear 166 may be directly attached to the gear 172. As shown, the shaft 168, gear 170, and gear 172 may each receive a shaft 136 and may be substantially concentric with the shaft 136. Although not specifically shown, it should be understood that the powertrain 106 may include various bearings for concentrically supporting these components. Specifically, shaft 168 can be rotatably attached to shaft 136 via a bearing, and gear 172 can be rotatably attached to shaft 168 via another bearing.

[0030] On the opposite side of converter 150 ( Figure 2 On the shaft 174 (from left to right), gear 148 can be mounted (e.g., fixed) to shaft 174, which also supports a first sun gear 154 and a second sun gear 162. In some embodiments, shaft 174 may be hollow and may receive shaft 136. Bearings (not shown) may rotatably support shaft 174 on shaft 136 in a substantially concentric manner. Furthermore, a first planetary gear and associated carrier 156 may be attached to gear 176. Gear 176 may mesh with gear 178 fixed to shaft 180. Shaft 180 may be substantially parallel to and spaced from shaft 136.

[0031] As described above, the powertrain 106 can be configured to transmit power (from the engine 114, the first electric motor 116a, and / or the second electric motor 116b) via the transmission 118 to the output shaft 230 or other output components. The output shaft 230 can be configured to transmit the received power to the wheels of the work vehicle 100, the power take-off (PTO) shaft, the auxiliary transmission, the implements, or other components of the work vehicle 100.

[0032] The powertrain 106 can have multiple selectable modes, such as direct drive mode, split mode, and series mode. In direct drive mode, power from engine 114 can be transmitted to output shaft 230, and power from second electric motor 116b can be prevented from being transmitted to output shaft 230. In split mode, power from engine 114 and second electric motor 116 can be added by converter 150, and the added or combined power can be transmitted to output shaft 230. Furthermore, in series mode, power from second electric motor 116b can be transmitted to output shaft 230, and power from engine 114 can generally be prevented from being transmitted to output shaft 230. The powertrain 106 can also have different speed modes in more than one of the direct drive mode, split mode, and series mode, and these different speed modes can provide different angular velocity ranges for output shaft 230. The powertrain 106 can switch between multiple modes to maintain appropriate operating efficiency. Furthermore, the powertrain 106 may have one or more forward modes for moving the work vehicle 100 in the forward direction and one or more reverse modes for moving the work vehicle 100 in the reverse direction. The powertrain 106 may, for example, use a control component 182 to implement different modes and speeds. The control component 182 may include one or more selectable transmission components. Selectable transmission components may have a first position or state (engaged position or state), wherein the corresponding device effectively transmits all power from the input component to the output component. Selectable transmission components may also have a second position or state (disengaged position or state), wherein the device prevents power transmission from the input to the output component. Selectable transmission components may have a third position or state (partially engaged or modulated position or state), wherein the corresponding device transmits only a portion of the power from the input component to the output component. Unless otherwise stated, the term "engaged" refers to the first position or state in which all power is effectively transmitted, while "partially engaged," "modulated," or "flickering" specifically refers only to partial power transmission, although they may have different characteristics. The selectable transmission components of the control assembly 182 may include one or more wet clutches, dry clutches, ring gear clutches, brakes, synchronizers, or other similar devices. The control assembly 182 may also include actuators for actuating the selectable transmission components between a first position, a second position, and a third position.

[0033] like Figure 2 As shown, the control assembly 182 may include a first clutch 184, a second clutch 186, a third clutch 188, a fourth clutch 190, and a fifth clutch 192. Additionally, the control assembly 182 may include a forward-oriented clutch 194 and a reverse-oriented clutch 196.

[0034] In one example, a first clutch 184 may be mounted and supported on shaft 198. Additionally, in the engaged position, the first clutch 184 can engage gear 146 with shaft 198 for rotation as a unit. In the disengaged position, the first clutch 184 can allow gear 146 to rotate relative to shaft 198. Furthermore, gear 200 may be fixed to shaft 198, and gear 200 may mesh with gear 170 fixed to shaft 168. A reverse-directional clutch 196 may be supported on shaft 198 (i.e., supported on shaft 198 together with the first clutch 184). The reverse-directional clutch 196 can engage gears 200 and 202, and optionally disengage gears 200 and 202. Gear 202 can mesh with idler gear 204, and idler gear 204 can mesh with gear 206. A forward-directional clutch 194 may be supported on gear 206 (gear 206 in turn is supported on shaft 136) to selectively engage shaft 168. Therefore, the forward-oriented clutch 194 can be concentric with both shaft 168 and shaft 136. The second clutch 186 can be supported on shaft 180. The second clutch 186 can engage shaft 180 and gear 208, and alternatively disengage shaft 180 and gear 208. Gear 208 can mesh with gear 210. Gear 210 can be fixed to and mounted on countershaft 212. Countershaft 212 can also support gear 214. Gear 214 can mesh with gear 216 fixed to output shaft 230.

[0035] The third clutch 188 can be supported on shaft 218. Shaft 218 can be substantially parallel to shaft 180 and separated from shaft 180 by a certain distance. Additionally, gear 220 can be fixed to and supported by shaft 218. Gear 220 can mesh with gear 172, as shown. The third clutch 188 can engage and optionally disengage gears 220 and 222. Gear 222 can mesh with gear 210. The fourth clutch 190 can be supported on shaft 180 (commonly with the second clutch 186). The fourth clutch 190 can engage and optionally disengage shaft 180 and gear 224. Gear 224 can mesh with gear 226 mounted and fixed to shaft 212. Additionally, the fifth clutch 192 can be supported on shaft 218 (commonly and concentrically with the third clutch 188). The fifth clutch 192 can engage the shaft 218 and the gear 228, and alternatively disengage the shaft 218 and the gear 228. The gear 228 can mesh with the gear 226.

[0036] Now, different transmission modes of the powertrain 106 will be discussed. Similar to the embodiments discussed above, the powertrain 106 may have at least one split mode in which power from the engine 114 and power from one or more of the electric motors 116a, 116b are combined. In addition, the powertrain 106 may also have a direct drive mode and / or at least one series mode (i.e., electric motor only mode).

[0037] In some embodiments, engaging the first clutch 184 and the second clutch 186 can place the powertrain 106 into a first forward mode. Typically, this mode can be a series mode (i.e., electric motor only). In this mode, mechanical power from the engine 114 can flow to the first electric motor 116a via shaft 130, gear 132, gear 138, and shaft 140. The first electric motor 116a can convert the input mechanical power into electro- or hydraulic power and supply the converted power to the second electric motor 116b. Additionally, power from the engine 114 (which flows to shaft 136 via shaft 130, gear 130, and gear 134) is nominally prevented from being input to the converter 150. Furthermore, mechanical power from the second electric motor 116b can rotate shaft 142 and the attached gear 144. This power from the electric motor 116b can rotate gear 148, thereby rotating the first sun gear 154. Power can also rotate gear 146, thereby transmitting power across the first clutch 184 to shaft 198, gear 200, gear 170, shaft 168, the second planetary gear and associated carrier 164, and the first ring gear 158. In other words, in this mode, power from the second electric motor 116b can drive the rotation of two components of the converter 150 (the first sun gear 154 and the first ring gear 158), and this power can be added and recombinated at the first planetary gear and associated carrier 156. The recombinated power can be transmitted via gears 176 and 178 to shaft 180. Power at shaft 180 can be transmitted across the second clutch 186 to gears 208 and 210, along the secondary shaft 212 to gears 214 and 216, and finally to output shaft 230. In some embodiments, the series mode can provide relatively high torque to output shaft 230 at low angular velocity output. Therefore, in some embodiments, this mode can be referred to as the crawling mode. Furthermore, as will become apparent, the first clutch 184 can be used only in this mode; therefore, the first clutch 184 can be referred to as a "creep clutch". In other words, the second motor 116b rotates the first sun gear 154 and the first ring gear 158, and as a result, the power from the second motor 116b is recombined at the first planetary gear and carrier 156.

[0038] In some embodiments, engaging the forward-oriented clutch 194 and the second clutch 186 can place the powertrain 106 in a first forward-oriented mode. This mode can be a split mode, in which the converter 150 adds the power from the second electric motor 116b and the power from the engine 114 and outputs the combined power to the output shaft 230. Specifically, the power from the second electric motor 116b is transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the first sun gear 154. Additionally, the power from the engine 114 is transmitted to shaft 130, gears 132, 134, shaft 136, and gear 206, and via the forward-oriented clutch 194, to shaft 168, the second planetary gear and associated carrier 164, and the first ring gear 158. The combined power from the second electric motor 116b and the engine 114 is added at the first planetary gear and associated carrier 156 and transmitted via gears 176 and 178 to shaft 180. The power at shaft 180 can be transmitted across the second clutch 186 to gears 208 and 210, along the secondary shaft 212 to gears 214 and 216, and finally to the output shaft 230.

[0039] Additionally, in some embodiments, engaging the forward-directing clutch 194 and the third clutch 188 can place the powertrain 106 into a second forward-directing mode as an additional branching mode. Specifically, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the second sun gear 162. Additionally, power from the engine 114 is transmitted to shafts 130, 132, 134, 136, and 206, and via the forward-directing clutch 194, to shaft 168, the second planetary gear, and the associated carrier 164. The combined power from the second electric motor 116b and the engine 114 can be added at the second ring gear 166 and transmitted to gears 172 and 220, and via the third clutch 188 to gears 222, 210, countershaft 212, 214, and 216, and finally to the output shaft 230.

[0040] Additionally, in some embodiments, engaging the forward-directing clutch 194 and the fourth clutch 190 can place the powertrain 106 into a third forward-directing mode as another branching mode. Specifically, power from the second electric motor 116b is transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the first sun gear 154. Power from the engine 114 is transmitted to shaft 130, gears 132, 134, shaft 136, and gear 206, and via the forward-directing clutch 194, to shaft 168, the second planetary gear and its associated carrier 164, and the first ring gear 158. The combined power from the second electric motor 116b and the engine 114 is added at the first planetary gear and its associated carrier 156 and transmitted via gears 176 and 178 to shaft 180. The power at shaft 180 can be transmitted across the fourth clutch 190 to gears 210 and 226, along the secondary shaft 212 to gears 214 and 216, and finally to the output shaft 230.

[0041] Furthermore, in some embodiments, engaging the forward-directing clutch 194 and the fifth clutch 192 can place the powertrain 106 in a fourth forward-directing mode as an additional branching mode. Specifically, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the second sun gear 162. Additionally, power from the engine 114 is transmitted to shafts 130, 132, 134, 136, and 206, and via the forward-directing clutch 194, to shaft 168, the second planetary gear, and the associated carrier 164. The combined power from the second electric motor 116b and the engine 114 can be added at the second ring gear 166 and transmitted to gears 172 and 220, and via the fifth clutch 192 to gears 228 and 226, the countershaft 212, gears 214 and 216, and finally to the output shaft 230.

[0042] The powertrain 106 may also have one or more reverse modes to drive the work vehicle 100 in the opposite (reverse) direction to those modes discussed above. In some embodiments, the powertrain 106 may provide a reverse series mode corresponding to the forward series mode discussed above, in which the first clutch 184 and the second clutch 186 may engage, such that the second electric motor 116b drives the shaft 142 and other downstream components in the opposite direction to the aforementioned direction, thereby causing the work vehicle 100 to move in the reverse direction.

[0043] Furthermore, the powertrain 106 can have multiple branching reverse direction modes. In some embodiments, the powertrain 106 can provide a reverse direction mode corresponding to the forward direction mode discussed above; however, the reverse-direction clutch 196 can engage instead of the forward-direction clutch 194 to achieve the reverse mode.

[0044] Therefore, the powertrain 106 can provide a first reverse direction mode by engaging the reverse-direction clutch 196 and the second clutch 186. In this way, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the first sun gear 154. Additionally, power from the engine 114 can be transmitted to shaft 130, gears 132, 134, shaft 136, gear 206, idler gear 204, and gear 202, and via the reverse-direction clutch 196 to gears 200, 170, shaft 168, the second planetary gear and its associated carrier 164, and the first ring gear 158. The combined power from the second electric motor 116b and the engine 114 can be added at the first planetary gear and its associated carrier 156 and transmitted via gears 176 and 178 to shaft 180. The power at shaft 180 can be transmitted across the second clutch 186 to gears 208 and 210, along the secondary shaft 212 to gears 214 and 216, and finally to the output shaft 230.

[0045] The powertrain 106 can also provide a second reverse direction mode by engaging the reverse-direction clutch 196 and the third clutch 188. In this way, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the second sun gear 162. Additionally, power from the engine 114 can be transmitted to shaft 130, gears 132, 134, 136, gear 206, idler gear 204, and gear 202, and via the reverse-direction clutch 196 to gears 200, 170, shaft 168, the second planetary gear, and the associated carrier 164. The combined power from the second electric motor 116b and the engine 114 can be added at the second ring gear 166 and transmitted to gears 172 and 220, and via the third clutch 188 to gears 222, 210, countershaft 212, gears 214, and 216, and finally to the output shaft 230.

[0046] Additionally, in some embodiments, engaging the reverse-direction clutch 196 and the fourth clutch 190 can place the powertrain 106 into a third reverse-direction mode. Specifically, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the first sun gear 154. Additionally, power from the engine 114 can be transmitted to shaft 130, gears 132, 134, shaft 136, gear 206, idler gear 204, and gear 202, and via the reverse-direction clutch 196 to gears 200, 170, shaft 168, the second planetary gear and associated carrier 164, and the first ring gear 158. The combined power from the second electric motor 116b and the engine 114 can be added at the first planetary gear and associated carrier 156 and transmitted via gears 176 and 178 to shaft 180. The power at shaft 180 can be transmitted across the fourth clutch 190 to gears 210 and 226, along the secondary shaft 212 to gears 214 and 216, and finally to the output shaft 230.

[0047] Furthermore, in some embodiments, engaging the reverse-direction clutch 196 and the fifth clutch 192 can place the powertrain 106 into a fourth reverse-direction mode. Specifically, power from the second electric motor 116b can be transmitted from shaft 142 to gears 144, 148, and shaft 174 to drive the second sun gear 162. Additionally, power from the engine 114 can be transmitted to shafts 130, 132, 134, 136, 206, idler gears 204 and 202, and via the reverse-direction clutch 196 to gears 200, 170, shaft 168, the second planetary gear, and the associated carrier 164. The combined power from the second electric motor 116b and the engine 114 can be added at the second ring gear 166 and transmitted to gears 172 and 220, and via the fifth clutch 192 to gears 228, 226, countershaft 212, 214, and 216, and finally to the output shaft 230.

[0048] Furthermore, the powertrain 106 can provide one or more direct drive modes, in which power from the engine 114 is transmitted to the output shaft 230, and power from the second electric motor 116b is prevented from being transmitted to the output shaft 230. Specifically, engaging the second clutch 186, the third clutch 188, and the forward-directing clutch 194 can provide a first forward direct drive mode. Thus, power from the engine 114 can be transmitted from the shaft 130 to gears 132, 136, and 206, and then via the forward-directing clutch 194 to the second planetary gear and carrier 164 and the first ring gear 158. Furthermore, with the second clutch 186 and the third clutch 188 engaged, the second ring gear 166 and the first planetary gear and carrier 156 are locked to the countershaft 212 at a fixed ratio, and therefore to the output shaft 230. This effectively limits the ratio on each side of the converter 150 and directly locks the engine speed to the ground speed of the work vehicle 100 by a ratio determined by the tooth count of the engaged gear train. In this configuration, the speeds of the sun gears 154 and 162 are fixed, and the sun gears 154 and 162 transmit torque between the two sides of the transmission 150. Furthermore, the first electric motor 116a and the second electric motor 116b may not be energized.

[0049] Similarly, engaging the fourth clutch 190, the fifth clutch 192, and the forward-directing clutch 194 can provide a second forward direct drive mode. Furthermore, engaging the second clutch 186, the third clutch 188, and the reverse-directing clutch 196 can provide a first reverse direct drive mode. Additionally, engaging the fourth clutch 190, the fifth clutch 192, and the reverse-directing clutch 196 can provide a second reverse direct drive mode. As described above, the controller 104 is coupled to control various aspects of the powertrain control system 102, including the engine 114 and the transmission 118, to achieve engine throttle shifting functionality.

[0050] Still referencing Figure 3 The data flow diagram illustrates an implementation of a powertrain control system 102, comprised of controller 104, engine 114, and transmission 118, to perform clutch modulation functions for electric motor stall prevention and / or migration. Typically, controller 104 can be considered a vehicle controller, a dedicated controller, or a combination of engine and / or transmission controllers. Relative to... Figure 3 The power control system 102 and controller 104 can be organized into one or more functional units or modules 240, 242 (e.g., software, hardware, or a combination thereof). As will be understood, Figure 3Modules 240 and 242 shown herein can be combined and / or further divided to perform functions similar to those described herein. As an example, each of modules 240 and 242 can be implemented using a processing architecture such as processor 244 and memory 246, along with a suitable communication interface. For example, controller 104 can implement modules 240 and 242 together with processor 244 based on programs or instructions stored in memory 246. In some examples, the consideration and implementation of clutch modulation function by controller 104 is continuous, e.g., continuously active. In other examples, activation of engine throttle shifting function can be selective, e.g., enabled or disabled based on input from the operator or other considerations. In any case, engine throttle function can be enabled and implemented by power control system 102, as described below.

[0051] Typically, controller 104 can receive various forms of input data and / or input data from multiple sources, including sensor 110, although such input data can also come from other systems or controllers inside or outside the work vehicle 100. This input data can represent any data sufficient to operate electric motors 116a, 116b, engine 114, and / or transmission 118, particularly any data sufficient to perform the clutch modulation functions described below.

[0052] In one example, controller 104 can be considered to include transmission control module 240 and electric motor control module 242. Typically, transmission control module 240 is configured to generate clutch commands for operating transmission 118 based on various types of data, including ground speed and operator input, as shown. Clutch commands can be generated at "shift points" where the command causes the clutch of transmission 118 to engage (e.g., ...). Figure 2 Clutches 184, 186, 188, 190, 192, 194, 196) at the output end (e.g., Figure 2 A new gear ratio or speed ratio is provided at shaft 230. This operation can be achieved based on one or more shift rules stored in memory 246. As described below, the transmission control module 240 can also implement at least a portion of the clutch modulation function.

[0053] Typically, the motor control module 242 can generate commands to operate one or more of the motors 116a and 116b, including commands associated with typical operations of the motors 116a and 116b, such as speed commands, shutdown commands, timing commands, etc. Motor commands can be based on multiple factors, including the current motor speed. Other parameters affecting the motor commands generated by the motor control module 242 can include operating parameters and parameters transmitted via the operator interface 122. Figure 1The operator input and the current and expected mode or gear ratio commanded by the transmission control module 240. In some examples, motor commands can be generated based on a predetermined operation schedule stored in memory 246.

[0054] During typical operation (e.g., without clutch modulation function), transmission control module 240 generates commands for the various clutches of transmission 118 to achieve an arranged transmission mode, such that the selected clutch is fully engaged or fully disengaged; and electric motor control module 242 generates associated electric motor commands, particularly speed commands. As described below, electric motor control module 242 and / or transmission control module 240 can implement clutch modulation function to improve powertrain performance under certain conditions.

[0055] Specifically, during operation, the motor control module 242 can receive clutch mode commands (as a basis for clutch commands to the transmission 118) to monitor the current mode of the transmission 118. In one example, the motor control module 242 can identify and / or be notified when the transmission 118 is in series mode, for example, when the second motor 116b is providing output torque to the transmission 118. The motor control module 242 can also monitor the motor speed, for example, Figure 2 The speed of motor 116b in the example. Other parameters, such as output or ground speed, may be considered. In any case, the motor control module 242 can determine when the conditions of the powertrain 106 cause the second motor 116b (and / or other motor 116a) to be approaching or decreasing below the stall speed threshold, typically as a result of deceleration of the vehicle 100 or transmission 118. In other words, the motor control module 242 can identify when the vehicle 100 encounters a reaction force on the vehicle 100 or transmission 118 that is causing the motor 116b to decelerate, such as when engaging a heavy load or driving on a steep incline (which could cause the motor to stall).

[0056] Typically, the stall speed threshold is the speed threshold at which a motor may be adversely affected due to inadequate rotation (e.g., when using asymmetrical phases or windings). Typically, the motor control module 242 (and / or other modules or systems) can reduce or decrease the torque capability of the main motor under these conditions to avoid thermal problems. The stall speed threshold can be based on the size or type of the motor. In one example, the stall speed threshold could be 25 rpm, 50 rpm, 100 rpm, 250 rpm, or 500 rpm, although any suitable stall speed threshold can be considered.

[0057] Brief Reference Figure 4A , Figure 4AThe example data for motor performance based on motor speed is represented by 250. Specifically, Figure 4A Representation 250 depicts the variation of the motor torque capability (Nm) with changes in motor speed (RPM). Representation 250 also depicts various reference speeds 260, 262, 264, and 266. Reference speed 260 is the maximum speed of the motor; reference speed 262 is the basic speed of the motor; reference speed 264 is the stall speed threshold; and reference speed 266 is another stall speed threshold. As shown, the torque capability is the largest of the stall speed threshold 264 and the basic speed 262. At speeds higher than the basic speed 262, the torque capability decreases, including decreasing until the maximum speed 260 is reached. At speeds lower than the stall speed threshold 264, the motor reduces power, as reflected in the decrease in torque capability. The torque capability continues to decrease from the stall speed threshold 264 until another stall speed threshold 266, at which the reduced torque capability remains constant. As described below, the clutch modulation function attempts to keep the motor at a speed above the stall speed threshold (e.g., threshold 264) in order to maximize the motor's torque capability.

[0058] Return to Figure 3 As discussed above, the motor control module 242 can monitor the motor speed relative to a stall speed threshold to identify motor stall conditions, and once identified, the motor control module 242 can generate a motor stall prevention command for the transmission control module 240. In one example, the motor control module 242 specifically monitors motor 116b, which, as referenced below, is responsible for providing torque to the transmission 118 in series mode. As mentioned above, in some examples, the motor control module 242 can generate a motor stall prevention command only when the transmission is in series mode, although in other examples, the motor control module 242 can generate a motor stall prevention command for the transmission control module 240 independently of clutch mode (e.g., in modes other than series mode).

[0059] Upon receiving a motor stall prevention command, the transmission control module 240 can generate a modified clutch command (e.g., a clutch command with a clutch modulation command for at least one clutch) according to the clutch modulation function to address potential stall of the motor 116b. Typically, the clutch command generated according to the clutch modulation function is used to "modulate" (or partially engage) another engaged clutch within the power flow path of the transmission 118. For example, in the above reference... Figure 2In the first forward mode (also the series mode) described above, clutch commands can be used to modulate the first clutch 184 that connects the second electric motor 116b to other parts of the transmission 118. In another example, as referenced above... Figure 2 In the first forward mode described, clutch commands can be used to modulate the second clutch 186 that connects the second electric motor 116b to other parts of the transmission 118. In other examples, both clutches 184 and 186 can be modulated. Typically, the transmission control module 242 can select one or more clutches most suitable for modulation, for example, one or more clutches that can accommodate the heat or friction of clutch slip associated with modulation.

[0060] Clutch modulation is used to at least partially disengage the electric motor 116b from the reduced-speed transmission 118. In particular, a power flow clutch (e.g., clutch 184) is allowed to slip, such that the clutch element on the input side of the power flow path (e.g., the electric motor 116b side) moves at a higher speed than the relative clutch element on the output side (e.g., the output shaft 230 side).

[0061] Clutch modulation can be achieved in various ways. In one example, clutch modulation can occur due to a selected clutch that vibrates (e.g., a regular, rapid increase and decrease within a defined bandwidth relative to the average pressure obtained at the clutch). This vibration can be in the form of a step, sawtooth, sinusoidal, and / or other shape or function (e.g., as an open-loop function). In the example, upon initiating clutch modulation with vibration, controller 104 can initially command the clutch torque to decrease from the engagement pressure to a reduced clutch pressure lower than the normal or engaged clutch pressure. The reduced clutch pressure can vary with the dispatch or be determined to vary with the motor speed or output speed. The clutch pressure can then rise and fall with approximately equal amplitudes (e.g., oscillating or alternating). The resulting average clutch pressure can increase or decrease with the motor speed and terminate when the motor speed reaches a sufficient value. In other examples, the power control system can achieve clutch modulation by aligning the obtained pressure of intermediate or partial engagement with the clutch (e.g., as a closed-loop function).

[0062] As a result of clutch modulation, electric motor 116b may be able to reach and / or maintain a speed above the stall speed threshold. Controller 104 can continue to monitor parameters and maintain clutch modulation until conditions render the clutch modulation function unnecessary. Specifically, controller 104 can terminate the clutch modulation function when the ground speed or transmission output speed exceeds the stall speed threshold of electric motor 116b. At this time, electric motor control module 242 can terminate the electric motor stall prevention command that received the clutch modulation function, and transmission control module 240 can generate a clutch command that causes the previously modulated clutch (e.g., clutch 184) to fully engage, e.g., in normal or nominal operation. Additional details will be provided below.

[0063] Now refer to Figure 4B , Figure 4B This is a data representation 270 depicting the powertrain parameters before, during, and after the implementation of the stall prevention clutch modulation function. Specifically, the data representation 270 depicts the corresponding relative amplitudes of various parameters on the vertical axis as time changes on the horizontal axis.

[0064] Data representation 270 includes: a first line 272 reflecting the transmission output speed (e.g., at output shaft 230) over time; a second line 274 reflecting the clutch torque (e.g., for a clutch associated with a clutch modulation function, such as clutch 184) over time; a third line 276 reflecting the relative speed of the clutch elements (e.g., representing the amount of clutch slip) over time; a fourth line 278 reflecting the electric motor speed (e.g., electric motor 116b) over time; a fifth line 280 reflecting the transmitted or current electric motor torque capability over time; a sixth line 282 reflecting the commanded or desired electric motor torque over time; a seventh line or reference point 284 reflecting the activation of the clutch modulation function; an eighth line 286 reflecting the effective or average clutch torque (e.g., the modulated clutch torque for line 274); and a ninth line or reference point 288 reflecting the point at which the transmission output speed 272 exceeds the electric motor speed 278.

[0065] As shown, when the transmission output speed 272 is relatively low (e.g., at the stall speed threshold), the clutch modulation function is activated (indicated at point 284). Before point 284, the clutch torque 274 is fully engaged, making the relative clutch element speed 276 approximately zero; and because the transmission output speed 272 is approximately zero, the clutch torque 274 is fully engaged, and the electric motor speed 278 is relatively low, so the electric motor transmits a torque 280 less than the desired electric motor torque 282. In other words, the electric motor cannot transmit the desired torque until the clutch modulation function is activated at point 284.

[0066] At point 284, the clutch modulation function is activated, and specifically, the clutch (e.g., clutch 184) undergoes vibration. With clutch vibration, the clutch torque 274 initially decreases, then experiences a relatively rapid increase and decrease to approximately the average amplitude or magnitude 286, causing an increase in the relative clutch element speed 276 (e.g., clutch slippage occurs), which in turn allows the motor speed 278 to increase. As shown, the transmitted torque 280 increases with increasing motor speed 278.

[0067] At point 288, the transmission output speed 272 ensures that full engagement of the clutch will no longer cause the electric motor to have a speed 278 that would stall the motor. As a result, the stall prevention modulation function can be terminated, and the clutch torque 274 can cause the clutch to fully engage, for example, by reducing the relative clutch element speed 276 to zero. Subsequently, the electric motor continues to increase speed 278 and continues to transmit the requested torque 280.

[0068] The power control system discussed herein can also be implemented as a method for controlling the powertrain of a work vehicle. Specifically, the method includes: initiating and monitoring the motor speed of at least one electric motor using a controller; and generating and executing a clutch modulation command for the transmission at the controller, such that at least one portion of a plurality of clutches along the power flow path engages when the motor speed is less than a first predetermined stall speed threshold. The generation and execution steps may include generating and executing the clutch modulation command to cause at least one clutch to vibrate. Additionally, the generation and execution steps may include generating and executing the clutch modulation command to subject at least one clutch to repeated modulation under clutch pressures between higher and lower amplitudes. The method may terminate when the motor speed exceeds the first predetermined stall speed threshold.

[0069] Therefore, this disclosure provides a power control system and method for a powertrain of a work vehicle having an engine and at least one electric motor that generates power regulated by a transmission (such as an eIVT). Specifically, the power control system and method provide improved performance and efficiency, especially in low-speed, high-torque applications.

[0070] In addition, the following examples are provided and numbered for easier reference.

[0071] 1. A control system for a work vehicle, the control system comprising: a power source including an engine configured to generate power and at least one electric motor; a transmission including a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and the at least one electric motor along a power flow path to drive the output shaft of a powertrain of the work vehicle; and a controller coupled to the power source and the transmission, the controller having a processor memory architecture configured to: monitor the electric motor speed of the at least one electric motor; and when the electric motor speed is less than a first predetermined stall speed threshold, generate and execute a clutch modulation command for the transmission such that at least one clutch among the plurality of clutches along the power flow path partially engages.

[0072] 2. The control system according to Example 1, wherein the controller is configured to generate and execute the clutch modulation command to cause the at least one clutch to shudder.

[0073] 3. The control system according to Example 1, wherein the controller is configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between a higher amplitude and a lower amplitude.

[0074] 4. The control system according to Example 2, wherein the controller is configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between a higher amplitude and a lower amplitude.

[0075] 5. The control system according to Example 4, wherein the controller is configured to generate and execute the clutch modulation command such that the repetitive modulation occurs after the initial drop in clutch pressure when the clutch modulation command is initiated.

[0076] 6. The control system according to Example 5, wherein the controller is configured to continue the repetitive modulation around an average synthetic clutch pressure that increases with the increase of the motor speed.

[0077] 7. The control system according to Example 1, wherein once the clutch modulation command is generated and executed, the controller is configured to continue monitoring the motor speed and terminate the clutch modulation command when the motor speed exceeds the first predetermined stall speed threshold.

[0078] 8. The control system according to Example 1, wherein the multiple transmission modes include a series mode and a split mode, wherein in the series mode the output shaft of the powertrain is primarily driven by power from the at least one electric motor, and in the split mode the output shaft of the powertrain is driven by a combination of power from the engine and the at least one electric motor, and wherein the controller is configured to generate and execute the clutch modulation command when the speed of the electric motor is less than a first predetermined stall speed threshold and the transmission is operating in the series mode.

[0079] 9. The control system according to Example 1, wherein the transmission is an electric continuously variable transmission (eIVT).

[0080] 10. A controller for a work vehicle, the work vehicle having: an engine configured to generate power and at least one electric motor; and a transmission having a plurality of clutches coupled together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine and the at least one electric motor along a power flow path to drive an output shaft, the controller including a processor memory architecture configured to: monitor the electric motor speed of the at least one electric motor; and when the electric motor speed is less than a first predetermined stall speed threshold, generate and execute a clutch modulation command for the transmission such that at least one clutch portion of the plurality of clutches along the power flow path engages.

[0081] 11. The controller according to Example 10, wherein the processor memory architecture is further configured to generate and execute the clutch modulation command, causing the at least one clutch to shudder.

[0082] 12. The controller according to Example 10, wherein the processor memory architecture is further configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between a higher amplitude and a lower amplitude.

[0083] 13. The controller according to Example 11, wherein the processor memory architecture is further configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between a higher amplitude and a lower amplitude.

[0084] 14. The controller according to Example 13, wherein the processor memory architecture is further configured to generate and execute the clutch modulation command such that the repetitive modulation occurs after the initial drop in clutch pressure when the clutch modulation command is initiated.

[0085] 15. The controller according to Example 14, wherein the processor memory architecture is further configured to continue the repetitive modulation around an average synthetic clutch pressure that increases with the speed of the electric motor.

[0086] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or variations thereof, when used in this specification, specify the presence of the stated feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0087] For ease of reference, particularly in the context of planetary gear sets, the term "component" may be used herein to indicate elements such as the sun gear, ring gear, or planetary carrier used for transmitting power. Additionally, references to "continuously variable" transmissions, powertrains, or power sources will be understood to also encompass configurations in various embodiments that include "infinitely" variable transmissions, powertrains, or power sources.

[0088] In the following discussion, various example configurations of shafts, gears, and other power transmission elements are described. It will be understood that various alternative configurations may be possible within the spirit of this disclosure. For example, various configurations may utilize multiple shafts instead of a single shaft (or use a single shaft instead of multiple shafts), one or more idler gears may be inserted between various shafts or gears to transmit rotational power, and so on.

[0089] As those skilled in the art will understand, certain aspects of the disclosed subject matter can be implemented as methods, systems (e.g., machine control systems included in machine operations), or computer program products. Therefore, some embodiments can be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or as a combination of software and hardware (and other aspects). Furthermore, some embodiments can take the form of a computer program product on a computer-usable storage medium, in which computer-usable program code is implemented.

[0090] As those skilled in the art will understand, aspects of the disclosed subject matter can be described in terms of methods, systems (e.g., control or display systems deployed on or otherwise integrated with operating machinery), and computer program products. In particular, embodiments of this disclosure may consist of or include tangible, non-transitory storage media storing computer-readable instructions or code for performing one or more functions described throughout the document, in contrast to computer program products. As will be readily apparent, such computer-readable storage media can be implemented using any currently known or subsequently developed memory type, including various types of random access memory (RAM) and read-only memory (ROM). Furthermore, embodiments of this disclosure are open or “unaware” of the specific memory technology employed, noting that magnetic storage solutions (hard disk drives), solid-state storage solutions (flash memory), optimal storage solutions, and other storage solutions can all potentially contain computer-readable instructions for performing the functions described herein. Similarly, the systems or apparatus described herein may also include memory storing computer-readable instructions (e.g., as any combination of firmware or other software executed on an operating system) that, when executed by a processor or processing system, instruct the system or apparatus to perform one or more functions described herein. When executed locally, such computer-readable instructions or code may be copied or distributed to the memory of a given computing system or apparatus in various different ways, for example, by transmission over a communications network including the Internet. Therefore, embodiments of this disclosure should generally not be limited to any particular set of hardware or memory structures, or to any particular manner of storing computer-readable instructions, unless otherwise expressly stated herein.

[0091] Computer-readable signal media may include, for example, a propagated data signal in baseband or as a portion of a carrier wave, in which computer-readable program code is implemented. Such propagated signals may take any of a variety of forms, including but not limited to electromagnetic, optical, or any suitable combination thereof. Computer-readable signal media may be non-transitory and may be any computer-readable medium that is not a computer-readable storage medium, and may convey, propagate, or transmit a program for use by or in connection with an instruction execution system, device, or apparatus.

[0092] As used herein, unless otherwise limited or modified, a list having elements separated by conjunctions (e.g., “and”) and preceded by the phrase “one or more” or “at least one” indicates a configuration or arrangement that potentially includes individual elements in the list or any combination thereof. 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).

[0093] As used herein, the term "module" refers to any hardware, software, firmware, electronic control components, processing logic, and / or processor device, whether standalone or in any combination, including but not limited to: application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or grouped) and memories executing one or more software or firmware programs, combinational logic circuits, and / or other suitable components that provide the described functionality. A module may be synonymous with unit, component, subsystem, subcontroller, circuit, routine, element, structure, control section, etc.

[0094] In this document, embodiments of the present disclosure can be described in terms of functional and / or logical block components and various processing steps. It should be understood that such block components can be implemented by any number of hardware, software, and / or firmware components configured to perform specific functions. For example, embodiments of the present disclosure can employ various integrated circuit components capable of performing various functions under the control of one or more microprocessors or other control devices, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc. Furthermore, those skilled in the art will understand that embodiments of the present disclosure can be implemented in conjunction with any number of work vehicles.

[0095] The description of this disclosure has been shown for illustrative and descriptive purposes, but it is not intended to be exclusive or limited to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments explicitly referenced herein have been selected and described in order to best explain the principles of this disclosure and its practical application, and to enable others skilled in the art to understand this disclosure and identify alternatives, modifications, and variations of the described examples. Therefore, various embodiments and implementations other than those explicitly described are within the scope of the following claims.

Claims

1. A control system (102) for a work vehicle (100), the control system (102) comprising: A power source (114, 116a, 116b) includes an engine (114) configured to generate power and at least one electric motor (116b); A transmission (118) comprising a plurality of clutches (184, 186, 188, 190, 192, 194, 196) connected together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine (114) and the at least one electric motor (116b) along a power flow path to drive the output shaft (230) of the powertrain (106) of the work vehicle (100); and A controller (104) connected to the power source (114, 116a, 116b) and the transmission (118), the controller (104) having a processor (244) and memory (246) architecture configured as follows: Monitor the motor speed of the at least one motor (116b); and When the speed of the electric motor is less than a first predetermined stall speed threshold, a clutch modulation command for the transmission (118) is generated and executed, such that at least one clutch portion of the plurality of clutches (184, 186, 188, 190, 192, 194, 196) along the power flow path is engaged.

2. The control system (102) of claim 1, wherein, The controller (104) is configured to generate and execute the clutch modulation command, causing the at least one clutch to shudder.

3. The control system (102) of claim 1, wherein, The controller (104) is configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between higher and lower amplitudes.

4. The control system (102) of claim 2, wherein, The controller (104) is configured to generate and execute the clutch modulation command such that the at least one clutch is subjected to repeated modulation under clutch pressure between higher and lower amplitudes.

5. The control system (102) of claim 4, wherein, The controller (104) is configured to generate and execute the clutch modulation command such that the repetitive modulation occurs after the initial drop in clutch pressure when the clutch modulation command is initiated.

6. The control system (102) of claim 5, wherein, The controller (104) is configured to continue the repetitive modulation around an average synthetic clutch pressure that increases as the speed of the electric motor increases.

7. The control system (102) of claim 1, wherein, Once the clutch modulation command is generated and executed, the controller (104) is configured to continue monitoring the motor speed and terminate the clutch modulation command when the motor speed exceeds the first predetermined stall speed threshold.

8. The control system (102) according to claim 1, wherein The various transmission modes include a series mode and a split mode. In the series mode, the output shaft (230) of the powertrain (106) is primarily driven by power from the at least one electric motor (116b). In the split mode, the output shaft (230) of the powertrain (106) is driven by a combination of power from the engine (114) and the at least one electric motor (116b). The controller (104) is configured to generate and execute the clutch modulation command when the speed of the electric motor is less than the first predetermined stall speed threshold and the transmission (118) is running in the series mode.

9. The control system (102) of claim 1, wherein, The transmission (118) is an electric continuously variable transmission (eIVT).

10. A controller (104) for a work vehicle (100) having: an engine (114) configured to generate power and at least one electric motor (116b); and a transmission (118) having a plurality of clutches (184, 186, 188, 190, 192, 194, 196) connected together and configured to selectively engage according to a plurality of transmission modes to transmit power from the engine (114) and the at least one electric motor (116b) along a power flow path to drive an output shaft (230), the controller (104) comprising: The processor (244) memory (246) architecture is configured as follows: Monitor the motor speed of the at least one motor (116b); and When the speed of the electric motor is less than a first predetermined stall speed threshold, a clutch modulation command for the transmission (118) is generated and executed, such that at least one clutch portion of the plurality of clutches (184, 186, 188, 190, 192, 194, 196) along the power flow path is engaged.

11. The controller (104) according to claim 10, wherein, The processor (244) and memory (246) architecture is also configured to generate and execute the clutch modulation command, causing the at least one clutch to shudder.

12. The controller (104) according to claim 10, wherein, The processor (244) and memory (246) architecture is also configured to generate and execute the clutch modulation command, such that the at least one clutch is subjected to repeated modulation under clutch pressure between higher and lower amplitudes.

13. The controller (104) according to claim 11, wherein, The processor (244) and memory (246) architecture is also configured to generate and execute the clutch modulation command, such that the at least one clutch is subjected to repeated modulation under clutch pressure between higher and lower amplitudes.

14. The controller (104) according to claim 13, wherein, The processor (244) and memory (246) architecture is also configured to generate and execute the clutch modulation command such that the repetitive modulation occurs after the initial drop in clutch pressure when the clutch modulation command is initiated.

15. The controller (104) according to claim 14, wherein, The processor (244) and memory (246) architecture is also configured to continue the repetitive modulation around the average synthetic clutch pressure, which increases as the speed of the electric motor increases.

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