Power takeoff assembly

Abstract

The utility model relates to a power takeoff assembly. In one example, a power takeoff assembly includes: a bidirectional pump in fluid communication with a fluid reservoir and a hydraulic system; and a disconnect clutch configured to mechanically disengage and disconnect the bidirectional pump from and from the transmission when the prime mover is operated, and to mechanically engage and connect the bidirectional pump to the transmission when the prime mover is turned off. The power takeoff assembly also includes an electromechanical valve configured to trigger engagement and disengagement of the disconnect clutch.

Description

Technical Field

[0001] The present disclosure relates to a ground drive power take-off (PTO) assembly having a disconnect clutch actuated with an electromechanical valve. Background Art

[0002] Powertrains and other systems utilize power take-offs (PTOs) to extend the operating capabilities of the powertrain and provide mechanical or hydraulic power to devices such as implements, auxiliary systems, etc. Some PTOs are driven by an engine or motor. For example, a live PTO utilizes the engine output shaft to deliver power to the PTO.

[0003] In existing transmissions, the oil supply to the transmission may be cut off when the vehicle is being towed. During long-distance towing, the lack of transmission lubrication may cause component degradation, thereby shortening the service life of the transmission. Utility Model Content

[0004] The inventor has recognized the above problems and developed a power take-off assembly to at least partially overcome these problems. In one example, the power take-off assembly includes a bidirectional pump in fluid communication with a fluid reservoir and a hydraulic system. The power take-off assembly also includes a disconnect clutch, which is configured to mechanically disengage and disconnect the bidirectional pump from the system (e.g., a transmission) when the prime mover is operating. The disconnect clutch is also configured to mechanically engage and connect the bidirectional pump to the system when the prime mover is disconnected. Further, in such an example, the power take-off assembly includes an electromechanical valve, which is configured to trigger the engagement and disengagement of the disconnect clutch. In this way, the bidirectional pump can provide hydraulic fluid (e.g., oil) to the transmission or other suitable system during the prime mover is disconnected and the transmission receives a rotational input, such as during traction operation and when the prime mover cannot operate and the vehicle is coasting. Therefore, during traction and other operating conditions, the chance of transmission component degradation is reduced, thereby extending the service life of the transmission. In addition, the use of a bidirectional pump in the power take-off assembly expands the functionality of the power take-off and allows the transmission to be ground driven in either direction of rotation. Furthermore, the use of an electromechanical valve allows the clutch to be engaged and disengaged efficiently and reliably. Thus, the power take-off assembly can more efficiently and reliably provide hydraulic fluid to the system when the prime mover is disconnected or inoperable.

[0005] In one example, the electromechanical valve can be a solenoid valve that causes the disconnect clutch to mechanically disengage when energized and mechanically engages when de-energized. In this way, when the prime mover is turned off and power generation stops, the clutch engages to bring the bidirectional pump online, causing the solenoid valve to be de-energized.

[0006] In another example, the disconnect clutch may include a first toothed surface coupled to a first gear that meshes with a second gear coupled to an output shaft comprising the output interface. Further, in such an example, the disconnect clutch may include a second toothed surface coupled to a shaft in a bidirectional pump. In this manner, the clutch may be incorporated into the transmission with efficient spacing, thereby increasing the compactness of the power take-off assembly.

[0007] It should be understood that the above utility model content is provided to introduce a selection of concepts further described in the detailed description in a simplified form. This is not meant to identify key or essential features of the claimed subject matter, and the scope of the claimed subject matter is uniquely defined by the claims following the detailed description. In addition, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of an electric drive unit having a transmission system including a power take-off (PTO) assembly.

[0009] Figure 2 is a schematic diagram of the power take-off assembly and lubrication system.

[0010] Figure 3 is a perspective view of an exemplary transmission.

[0011] Figure 4 yes Figure 3 A cross-sectional view of an exemplary ground driven power take-off assembly in a transmission is shown.

[0012] Figure 5A yes Figure 4 A cross-sectional view of a power take-off assembly depicted in FIG. 1 with the disconnect clutch in a disengaged state.

[0013] Figure 5B yes Figure 4 A cross-sectional view of a power take-off assembly depicted in FIG. 1 with the disconnect clutch in an engaged state.

[0014] Figure 6 It is a method used to operate the disconnect clutch when the prime mover is disconnected.

[0015] Figure 7 It is a method used to operate the disconnect clutch when the prime mover is started.

[0016] Figure 8 is a timing diagram for a use case scenario of a power take-off assembly with a disconnected clutch. DETAILED DESCRIPTION

[0017] This article describes a power take-off (PTO) assembly with a disconnect clutch and a bidirectional pump for use with a hydraulic system. The power take-off assembly is designed to operate when a transmission or other suitable system is driven by the ground, and is disconnected from the transmission when the bidirectional pump operation is not required. In this way, when the prime mover is disconnected and the wheels are rotating (for example, during traction), the power take-off assembly can provide fluid to the transmission during operation for lubrication and / or other purposes to reduce the chance of insufficient lubrication of the components. In addition, when the bidirectional pump operation will provide redundant hydraulic fluid flow, the power take-off assembly is disengaged during the operation of the prime mover to improve the efficiency of the transmission. In order to achieve the above functions, the power take-off assembly includes an electromechanical valve for engaging and disengaging the disconnect clutch, which allows and prevents the torque transfer between the transmission or other suitable system and the bidirectional pump. The energization of the electromechanical valve can keep the disconnect clutch disengaged, and conversely, the energization of the valve can cause the disconnect clutch to engage. The disconnect clutch is configured to disconnect the bidirectional pump from the transmission when the prime mover is operating, and mechanically connect the bidirectional pump to the transmission when the prime mover is disconnected. Thus, the transmission's hydraulic system provides hydraulic fluid to the transmission's hydraulic system during prime mover shutoffs to reduce the likelihood of component degradation and / or to provide other hydraulic functions, such as hydraulic steering functions. Additionally, the use of an electromechanical valve controlled by a suitable controller, such as a transmission control unit (TCU), allows the power take-off assembly to be engaged and disengaged more accurately and more robustly than a manually adjusted power take-off system or a hydraulically triggered actuator that passively engages and disengages the power take-off system based on oil temperature.

[0018] The power take-off assemblies described herein may be used in a transmission or other suitable systems. Figure 1 An exemplary transmission system having a power take-off assembly is shown in FIG. Figure 2 A schematic diagram of an exemplary hydraulic circuit in a power take-off assembly is depicted. Figure 3 , 4 Diagrams of exemplary power take-off assemblies and hydraulic systems are shown in 5A and 5B. Figure 6 and Figure 7 An operating method for a power take-off assembly is depicted in FIG. Figure 8 A use case scenario for the operation of a power take-off assembly is illustrated in the timing diagram of FIG.

[0019] Figure 1 A transmission system 100 and a power take-off assembly 112 are depicted. The transmission system 100 is shown as one example of an operating environment for the power take-off assembly 112. However, it should be understood that the power take-off assembly may be used in a variety of systems.

[0020] The transmission system 100 in the illustrated example may be included in an electric drive unit 102 of a vehicle 104 (e.g., a battery electric vehicle (BEV), although alternative examples are possible, such as a hybrid electric vehicle (HEV) that utilizes an internal combustion engine to propel and / or recharge an energy storage device. Furthermore, in other examples, the transmission system may be used in a vehicle powertrain that utilizes only an internal combustion engine as a prime mover.

[0021] Electric drive unit 102 generates motive force for vehicle propulsion. Vehicle 104 may be a road vehicle (e.g., a car or truck) or an off-road vehicle (e.g., a material handling, mining, or rail vehicle). More generally, vehicle 104 may be, for example, a light, medium, or heavy vehicle.

[0022] The electric drive unit 102 may include an electric motor 106 (e.g., an electric motor such as a traction motor). However, in other examples, another suitable prime mover may be used in place of the electric motor 106, such as an internal combustion engine or a hydraulic motor. The electric motor 106 may include components such as a rotor and a stator that interact electromagnetically during operation to generate a prime mover. Additionally, in one example, the electric motor may be a motor-generator designed to generate electrical energy during regenerative operation.

[0023] When the machine is designed as an alternating current (AC) machine, the electric motor 106 may be electrically coupled to one or more energy storage devices 108 (e.g., one or more traction batteries, (one or more) capacitors, (one or more) fuel cell cells, combinations of these, etc.) via an inverter 110. However, a direct current (DC) electric motor may also be used in alternative examples.

[0024] Arrow 114 represents the electrical connection between electric motor 106, inverter 110 and (one or more) energy storage device 108. Inverter 110 can be designed to convert direct current (DC) to alternating current, and vice versa. In one use case example, electric motor 106 and inverter 110 can be three-phase devices, which can achieve higher efficiency than other types of motors. However, motors and inverters designed to operate using alternative numbers of phases have been considered.

[0025] The electric motor 106 can be rotationally coupled to the transmission system 100. In addition, the transmission system 100 can include a multi-speed transmission 116 (e.g., a multi-speed gearbox) with multiple components. When the multi-speed transmission is used in an electric vehicle, it can be referred to as an electric multi-speed transmission. However, in other examples, the transmission can be a single-speed transmission. More generally, Figure 1 A possible transmission architecture is shown. However, it will be appreciated that in other examples, the transmission may have a variety of architectures.

[0026] The multi-speed transmission 116 may include one or more clutch assemblies, such as a higher-lower range clutch assembly 118 and a multi-speed clutch assembly 120. The higher-lower range clutch assembly 118 may be positioned downstream of the multi-speed clutch assembly 120. The higher-lower range clutch assembly 118 may include a higher range clutch 122 positioned coaxially with the output shaft 124 and a lower range clutch 126 positioned coaxially with the first countershaft 128. However, in another example, the higher range clutch may be positioned coaxially with the first countershaft, and the lower range clutch may be positioned coaxially with the output shaft. It should be understood that other clutch architectures in the transmission may be used. For example, the number, positioning and / or type of clutches used in the transmission may be changed to meet different end-use design goals.

[0027] The higher range clutch 122, as well as other clutches described herein, can be friction clutches (e.g., wet friction clutches). The friction clutches described herein can be operated with different amounts of engagement of the friction plates and spacers (e.g., continuously adjusted over the engagement range of the clutch). In addition, the friction clutches described herein can be wet friction clutches through which a fluid (e.g., oil) is directed to increase the life of the clutch. For example, a hydraulically operated piston can be used to cause the clutch to engage and disengage. However, in other examples, a solenoid can be used for electro-mechanical clutch actuation. The use of a friction clutch allows for reduced power interruption during shift transients, thereby improving transmission performance. However, in other examples, other types of clutches, such as a dog clutch, can be used in the transmission.

[0028] In this friction clutch example, the upper range clutch 122 includes an inner carrier 130 and an outer carrier 132. The inner carrier 130 has a first set of plates mounted to it, and the outer carrier 132 has a second set of plates mounted to it. When the clutch is closed, the plates can be frictionally engaged to allow torque to be transferred from the inner carrier 130 to the outer carrier 132. Conversely, when the clutch is open, the plates can be frictionally disengaged. Therefore, when the clutch is closed, the clutch can be in an engaged state, and when the clutch is open, the clutch can be in a disengaged state. The outer carrier 132 can be fixedly coupled to a gear 134, which is fixedly coupled to the output shaft 124. A bearing 136 can be used as a rotational connection between the inner carrier 130 and the output shaft 124. The bearing 136, as well as other bearings described herein, can include an inner race, an outer race, and roller elements (e.g., cylindrical rollers, tapered rollers, balls, etc.). Figure 1The inner clutch carrier depicted in FIG. 1 is shown coupled to a single bearing. However, it is understood that in other examples, the clutch carrier may be coupled to multiple bearings. In addition, the inner carrier 130 is fixedly coupled to a gear 138 that meshes with a gear 140 that is rotationally coupled to the first countershaft 128.

[0029] Also in the friction clutch example, the lower range clutch 126 includes an inner carrier 142 and an outer carrier 144, each of which has a different set of plates mounted thereto that function in a similar manner to the upper range clutch 122 with respect to engagement and disengagement of the plates. The other friction clutches of the multi-speed transmission 116 described herein also include plates that function in a similar manner, and for the sake of brevity, repeated descriptions of these plates are omitted. The inner carrier 142 may be fixedly coupled to a gear 146 that meshes with gear 134. In contrast, the outer carrier 144 may be fixedly coupled to a gear 140 that meshes with gear 138 and gear 148.

[0030] In the illustrated example, the upper range clutch 122 and the lower range clutch 126 are axially offset along their rotational axes 150 and 151. In this way, the space efficiency of the transmission is improved when compared to clutches having the same position along their respective rotational axes. However, in other examples, the upper range clutch and the lower range clutch may have alternating axial positions.

[0031] As shown, the output shaft 124 may include two mechanical interfaces 152 designed to be mechanically attached to downstream driveline components, such as shafts, joints, etc., which transfer mechanical power to drive axle assemblies 154, each of which may include a differential, an axle shaft (e.g., axle shafts), drive wheels, etc. This mechanical power transfer is represented via arrows 155. In other examples, the output shaft 124 may include one mechanical interface or more than two mechanical interfaces.

[0032] In the example shown, the output shaft 124 has a power take-off gear set 125 coupled thereto. In detail, the power take-off gear set 125 includes a gear 111 meshing with a gear 113. In the example shown, the gear 113 is rotatably coupled to the power take-off assembly 112. However, in alternative examples, the power take-off assembly 112 may use another suitable mechanical connection to receive mechanical power, and / or in other examples, be positioned at another suitable location within the transmission or powertrain, as described in more detail herein.

[0033] The power take-off assembly 112 is driven via rotation of the drive wheel 157, which transfers torque to the output shaft 124. In the example shown, the drive wheel is included in the drive axle assembly 154. Therefore, the power take-off assembly 112 can be referred to as a ground-driven power take-off assembly. For example, the power take-off assembly is driven in this manner during towing operations and vehicle coasting. Towing operations, as described herein, are operating conditions in which the prime mover is not operating and the vehicle drive wheels are rotating due to the vehicle 104 being attached to a towing vehicle (e.g., a trailer).

[0034] In the example shown, the power take-off assembly 112 provides hydraulic fluid (e.g., mineral-based oil and / or synthetic oil) to a hydraulic system 127, which in turn delivers the hydraulic fluid to components in the transmission that have hydraulic demands, such as clutches, bearings, steering systems, etc. Arrow 129 indicates a fluid connection between the power take-off assembly 112 and the hydraulic system 127, which is not referred to herein. Figure 2-5B However, in other examples, the power take-off assembly may deliver hydraulic fluid directly to the hydraulic components.

[0035] In one example, the power take-off gear set 125 can be incorporated into the power take-off assembly 112, and the power take-off assembly can be formed as a unit that is removably coupled to the output shaft 124. In this way, the power take-off assembly 112 can be more efficiently incorporated into the transmission at a later stage of the manufacturing process if desired, compared to a power take-off that is attached to the transmission at an upstream location. More generally, designing the power take-off assembly and gear as an integrated unit can make the power take-off assembly more easily integrated into various vehicle platforms to expand the functional capabilities of the vehicle.

[0036] As described above, the transmission 116 can have a variety of different architectures. For example, the number of shafts, gears, and other transmission components can be changed based on the end-use design goals of the system. As an example, the number of speeds in the transmission can be increased or decreased by increasing or decreasing the number of clutches and / or the type of clutches used in the transmission. In yet other examples, a single-speed or continuously variable transmission can be utilized.

[0037] In other examples, the power take-off gear set 125 and the power take-off assembly 112 can be positioned elsewhere in the transmission. For example, the power take-off gear set can be rotatably coupled to another suitable shaft, such as an intermediate shaft (e.g., an idler shaft), an input shaft, etc. and / or include a different number of gears. In addition, the power take-off assembly can be coupled to the transmission using additional or alternative suitable mechanical components, such as one or more belts, chains, shafts, combinations thereof, etc.

[0038] In the illustrated example, the multi-speed clutch assembly 120 includes two or more clutches arranged on the second countershaft 156 and the third countershaft 158. In detail, in the illustrated example, a first pair of clutches including a first gear clutch 160 and a third gear clutch 162 are positioned coaxially with the third countershaft 158, and a second pair of clutches including a second gear clutch 164 and a fourth gear clutch 165 are positioned coaxially with the second countershaft 156. However, other clutch arrangements have been contemplated.

[0039] The second gear clutch 164 may include an inner carrier 166 and an outer carrier 167. The inner carrier 166 may be fixedly coupled to gear 148, which meshes with gear 140. The outer carrier 167 may be fixedly coupled to the second countershaft 156.

[0040] The fourth gear clutch 165 may include an inner carrier 168 and an outer carrier 169. The inner carrier 168 may be fixedly coupled to gear 170 which meshes with gear 171 on the first countershaft 128. The outer carrier 169 may also be fixedly coupled to the second countershaft 156.

[0041] The first gear clutch 160 can include an inner carrier 172 and an outer carrier 173. The inner carrier 172 can be fixedly coupled to a gear 174 that is rotationally coupled to the gear 140, as indicated via arc 178. In other words, the gear 174 can mesh with the gear 140. However, in other examples, the gear 174 can be coupled to the gear 140 via a mechanical coupling, such as one or more gears, shafts, joints, etc. The inner carrier 172 can be fixedly coupled to the third countershaft 158.

[0042] The third gear clutch 162 can include an inner carrier 175 and an outer carrier 176. The inner carrier 175 can be fixedly coupled to a gear 177 that is rotationally coupled to a gear 179 on the first countershaft 128, as indicated by arc 180. In other words, the gear 177 can mesh with the gear 179. However, in other examples, the gear 177 can be coupled to the gear 179 via a mechanical coupling, such as one or more gears, shafts, joints, etc. The inner carrier 175 can be fixedly coupled to the third countershaft 158.

[0043] In the illustrated example, the multi-speed transmission 116 also includes an input assembly 181 that includes an input shaft 182 to which gear 183 and gear 184 are fixedly coupled. Gear 183 meshes with gear 185 that is fixedly coupled to the third countershaft 158. Gear 185 is rotationally coupled to gear 186 that is fixedly coupled to the second countershaft 156, as indicated by arc 187. In other words, gear 185 may mesh with gear 186. However, in other examples, gear 185 may be coupled to gear 186 via a mechanical coupling, such as one or more gears, shafts, joints, etc. In addition, gear 184 meshes with gear 188 that is rotationally coupled to an electric motor interface shaft 189. In turn, the electric motor interface shaft 189 is rotationally coupled to a rotor shaft in the electric motor 106.

[0044] Input shaft 182 also includes gear 107 rotationally coupled thereto. Gear 107 can mesh with gear 197, which can be rotationally coupled to pump 191 (e.g., a charge pump). Thus, electric motor 106 can provide mechanical power to pump 191. Pump 191 can provide pressurized fluid (e.g., mineral-based oil and / or synthetic oil) for actuation and / or lubrication of clutches and bearings and / or other components in the transmission that have a hydraulic fluid requirement (e.g., fluid actuation and / or lubrication requirements).

[0045] In one example, second electric motor 198 may be additionally coupled to multi-speed transmission 116 via gear 199 meshing with gear 184. However, in other examples, second electric motor 198 may be omitted from electric drive unit 102.

[0046] The output shaft 124 may be disposed below the countershafts 128, 156 and 158 and the input shaft 182. In this manner, the transmission achieves the desired step-down for a wide range of vehicles. However, in other examples, the output shaft may be positioned in another suitable position, such as above at least one countershaft.

[0047] The multi-speed transmission 116 may also include a bearing 147 coupled to the inner carrier of the clutch and a corresponding shaft coaxial with the inner carrier. In this manner, when the clutch is disengaged, the inner carrier may rotate independently relative to each shaft.

[0048] The vehicle 104 may also include a control system 190 having a controller 192 (eg, a transmission control unit (TCU)), such as Figure 1As shown. The controller 192 may include a microcomputer having components such as a processor 193 (e.g., a microprocessor unit), input / output ports, and an electronic storage medium 194 (e.g., a read-only memory chip, random access memory, keep-alive memory, data bus) for executable programs and calibration values. The storage medium may be programmed with computer-readable data representing instructions that are executable by the processor to perform the methods and control techniques described herein, as well as other variations that are anticipated but not specifically listed.

[0049] The controller 192 may receive various signals from sensors 195 coupled to various areas of the vehicle 104 and the multi-speed transmission 116. For example, the sensors 195 may include a pedal position sensor designed to detect depression of an operator-actuated pedal such as an accelerator pedal and / or a brake pedal, a speed sensor at the transmission output shaft, an energy storage device state of charge (SOC) sensor, a clutch position sensor, etc. The motor speed may be determined from the amount of power sent by the inverter to the electric motor. The input devices 145 (e.g., an accelerator pedal, a brake pedal, a drive mode selector, a gear selector, a combination of these, etc.) may further provide input signals indicative of operator intent for vehicle control.

[0050] Upon receiving Figure 1 When the controller 192 receives signals from various sensors 195 in the vehicle, the controller 192 processes the received signals and, based on the received signals and the instructions stored on the memory of the controller 192, uses various actuators 196 of the vehicle and / or transmission components to adjust the components. For example, the controller 192 may receive an accelerator pedal signal indicating an operator's request to increase vehicle acceleration. In response, the controller 192 may command the operation of the inverter 110 to increase the power delivered from the electric motor 106 to the multi-speed transmission 116. The controller 192 may be designed to send instructions to the clutches 122, 126, 160, 162, 164, 165 during certain operating conditions to engage and disengage the clutches. For example, a control instruction may be sent to the higher range clutch 122, and in response to receiving the instruction, the actuator in the clutch may adjust the clutch based on the instruction for the clutch to engage or disengage. For example, other controllable components in the vehicle may function in a similar manner in terms of sensor signals, control commands, and actuator adjustments. The methods, control schemes, etc. described herein may be implemented as instructions stored in an electronic storage medium 194 , which may be executed by a processor 193 of a controller 192 .

[0051] exist Figure 1 as well as Figure 2-5BA coordinate system is provided in for reference. In one example, the z-axis can be a vertical axis (e.g., parallel to the gravity axis), the x-axis can be a lateral axis (e.g., a horizontal axis), and / or the y-axis can be a longitudinal axis. However, in other examples, these axes can have other orientations.

[0052] The multi-speed transmission 116 can be designed to operate with the same number of forward and reverse drive gear modes. For example, in the illustrated example, the transmission has eight forward and reverse gear modes. However, it should be understood that the transmission can be designed to have a different number of gear modes, which can be symmetrical in some cases. For example, the transmission can have two, three, four, or sixteen forward and reverse gear modes.

[0053] To operate the multi-speed transmission 116 in the reverse drive mode, the electric motor 106 can rotate the rotor shaft in the opposite direction to the forward drive mode. Designing the electric motor 106 in this manner allows the transmission to be less compact when compared to a transmission with a mechanical reversing assembly. However, in other examples, the transmission may include a mechanical reverser, which would reduce the space efficiency of the system.

[0054] The transmission 116 is described as one possible exemplary embodiment, and other configurations of exemplary transmission systems having other configurations of clutches, gears, and / or shafts are possible without departing from the scope of the present disclosure. For example, in one example, the electric motor 106 and / or the electric motor 198 can be replaced with (one or more) internal combustion engines. In other examples, a multi-speed transmission can provide motive power to a first drive axle assembly while an internal combustion engine provides motive power to a second drive axle assembly. Further, in other embodiments, an internal combustion engine can be provided to recharge (one or more) energy storage devices 108. However, it should be understood that when the transmission is used in an all-electric vehicle, the system can be simplified, thereby reducing manufacturing costs and the chance of component degradation.

[0055] Figure 2 The hydraulic system 200 and the power take-off assembly 203 are schematically shown. It should be understood that Figure 2 The power take-off assembly 203 and hydraulic system 200 depicted in FIG. 2 and other power take-off assemblies described herein may include a Figure 1 In the transmission system shown or another suitable system. In addition, at least a portion of the components, features, etc. in the power take-off assembly 203 described herein may be included in other power take-off assemblies described herein, and vice versa.

[0056] The hydraulic system 200 may be configured to hydraulically actuate a plurality of clutches and / or supply hydraulic fluid to one or more hydraulic devices (eg, hydraulic steering components). The hydraulic system may include hydraulic valves, hydraulic lines, etc. to supply hydraulic fluid to lubricated components, steering systems, and / or clutches.

[0057] The hydraulic system 200 may include a plurality of hydraulic devices and a pressure relief valve 216 in fluid communication with a fluid reservoir 210 (e.g., an oil sump). The hydraulic system 200 may receive hydraulic fluid (e.g., a mineral-based oil and / or a synthetic oil) from the fluid reservoir 210. When a prime mover (e.g., an electric motor such as a traction motor and / or an internal combustion engine) is shut off, the hydraulic system 200 may function to provide fluid to a component 214 (e.g., a transmission component) having a hydraulic fluid demand. As described above, the component 214 may include lubricated components such as bearings, gears, etc. and / or hydraulically operated components such as clutches, steering systems, etc. As described herein, a prime mover shutoff is an operating condition in which the prime mover does not generate mechanical power and / or does not transmit mechanical power to downstream components.

[0058] During a prime mover shutdown, when the transmission output shaft or other suitable shaft coupled to the power take-off assembly rotates (e.g., during vehicle towing), the power take-off assembly 203 is designed to provide hydraulic fluid 214 to the one or more components via the hydraulic system 200. It will be appreciated that during a prime mover shutdown, one or more pumps 205 (e.g., lubricant pumps and / or hydraulic pumps for clutch and / or steering systems) may not be able to operate because they may be driven by the prime mover. In this way, a vehicle system (e.g., a transmission, a steering system, etc.) can be provided with hydraulic fluid for lubrication, clutch actuation, steering functions, and / or other uses during a prime mover shutdown (e.g., towing), thereby extending the service life of the system compared to a system without a ground-driven power take-off function. The pump 205 can be in fluid communication with a hydraulic line 256 at a junction 254. In addition, the hydraulic line 256 is in fluid communication with one or more hydraulic components 214 (e.g., transmission system components).

[0059] The power take-off assembly 203 includes a disconnect clutch 206 and a bidirectional pump 208 in a bidirectional pump assembly 231. In addition, the power take-off assembly 203 includes an electromechanical valve 202 (eg, a solenoid valve).

[0060] Fluid supply line 207 is in fluid communication with electromechanical valve 202. Fluid pressure in fluid supply line 207 may be proportional to fluid pressure in hydraulic system 200. In this manner, electromechanical valve 202 ensures hydraulic system pressure. In some examples, restriction 211 may be positioned in fluid supply line 207. Additionally, in one example, when the electromechanical valve is closed, hydraulic fluid may be returned to fluid reservoir 210 (or other suitable tank) through electromechanical valve 202 via exhaust line 258.

[0061] The electromechanical valve 202 is in fluid communication with the hydraulic actuator 204. When the electromechanical valve 202 is energized and allows fluid to flow therethrough, pressurized fluid is supplied from the electromechanical valve 202 to the hydraulic chamber 270 via the hydraulic supply line 280. Conversely, when the electromechanical valve 202 is de-energized, hydraulic fluid is prevented from flowing from the line 207 to the supply line 280 through the valve. In addition, a spring 282 is shown as being coupled to or incorporated into the electromechanical valve 202. However, other electromechanical valve designs have been contemplated. For example, the valve may be open and allow fluid to flow therethrough when it is de-energized, and may be closed and prevent fluid from flowing therethrough when energized. Further, in other examples, the electromechanical valve may be designed to switch to two flow configurations via energization, and the spring may be omitted from the valve.

[0062] In the example shown, the pressure within the hydraulic actuator 204 determines the configuration of the disconnect clutch 206. In addition, the operating state of the bidirectional pump 208 depends on the actuation state of the disconnect clutch 206 (engaged vs. disengaged).

[0063] In the illustrated example, the hydraulic actuator 204 includes a hydraulic chamber 270, an actuating piston 272, and a spring 240. However, hydraulic actuators having alternative configurations may be used in alternative embodiments. Figure 2 206, but the clutch actuator may be incorporated into the disconnect clutch, as will be further described below. The actuating piston 272 may slide axially in the hydraulic chamber 270. In some examples, the disconnect clutch 206 may be a hydraulically actuated dog clutch. However, in other examples, other types of hydraulically operated clutches may be used in the power take-off assembly.

[0064] The hydraulic actuator 204 is configured to regulate the disconnect clutch 206. In detail, the disconnect clutch 206 is designed to engage when the fluid pressure in the hydraulic chamber 270 drops below a threshold value (e.g., a positive non-zero value) to place the actuating piston 272 in the retracted position. In detail, the reduction in pressure in the hydraulic chamber 270 can reduce the force on the spring 240, causing the spring 240 to return the actuating piston 272 to the retracted position, thereby engaging the disconnect clutch 206. The disconnect clutch 206 can be designed to disengage when, due to the hydraulic pressure in the hydraulic chamber 270, the fluid pressure in the hydraulic chamber 270 is above a threshold value, causing the actuating piston 272 to move to the extended position and the spring 240 to compress.

[0065] As described above, the electromechanical valve 202 is designed to cause engagement and disengagement of the disconnect clutch 206. In detail, when the electromechanical valve 202 is energized, hydraulic fluid is allowed to flow from the fluid supply line 207 and through the valve to the supply line 280, and then to the disconnect clutch hydraulic chamber 270, which disengages the clutch when the fluid pressure is greater than a threshold. Conversely, when the electromechanical valve 202 is de-energized, hydraulic fluid is prevented from flowing through the valve and between the fluid supply line 207 and the supply line 280. Therefore, during de-energization, the pressure in the hydraulic chamber 270 drops and the disconnect clutch is engaged.

[0066] When the vehicle's prime mover switches from an operating state to an off state, the electromechanical valve 202 is de-energized (e.g., automatically de-energized), thereby engaging the disconnect clutch 206, which allows the dual-directional pump 208 to be grounded. Conversely, when the prime mover is operating, the electromechanical valve 202 is energized to disengage the disconnect clutch 206, which prevents the dual-directional pump 208 from being driven by the transmission. The specific conditions that may trigger the energization of the electromechanical valve are described herein with respect to Figure 5A-7 Expanded.

[0067] In one example, the bidirectional pump 208 can be a bidirectional fixed displacement hydraulic pump. In detail, the bidirectional pump 208 can be a positive displacement hydraulic pump having a housing and a pumping device (e.g., a reciprocating piston (e.g., a check ball piston pump) or a rotary device), which is designed to, for example, deliver pressurized fluid during each cycle. In addition, the bidirectional pump 208 can be in fluid communication with the fluid reservoir 210 via a pick-up line 248. In the illustrated example, the check valves 228 and 230 in the rectifier enable the bidirectional pump 208 to provide fluid (e.g., oil) to downstream components through rotational inputs in clockwise and counterclockwise directions. However, other pump arrangements that achieve bidirectional functionality can be used in other examples.

[0068] In addition, the bidirectional pump 208 can provide hydraulic fluid to the transmission during operations such as traction, during which the prime mover is turned off and the output shaft rotates in either a forward or reverse direction, as opposed to a unidirectional pump that can only be driven in one rotational direction. In this manner, the bidirectional pump 208 pressurizes the lubricating fluid and flows the lubricating fluid to the (one or more) components 214 via hydraulic lines 256, respectively. In addition, the hydraulic lines 256 can be in fluid communication with one or more lubricated components of the transmission via one or more additional hydraulic lines. Further, it should be understood that the pump input shaft 244 can be rotationally coupled to a transmission shaft, such as an output shaft.

[0069] The first port 224 (e.g., inlet) of the bidirectional pump 208 can be in fluid communication with a first pair of check valves 228, and the second port 226 (e.g., outlet) of the bidirectional pump 208 can be in fluid communication with a second pair of check valves 230. The first pair of check valves 228 can be configured to allow hydraulic fluid to flow from the fluid reservoir 210 to the second port 226. The check valves 228 and other check valves described herein allow lubrication fluid to flow in one direction when the pressure upstream of the valve exceeds a threshold value associated with the valve. The check valves 228 and 230 can be included in a bidirectional pump assembly 231.

[0070] The second pair of check valves 230 may be configured to allow fluid to flow from the second outlet 226 toward the hydraulic line 256. The paired check valves allow the pump to receive a rotational input in the opposite direction and supply fluid to downstream components. The fluid may then flow into a heat exchanger 212 (e.g., an oil cooler) before passing through another check valve 232 and then flowing to (one or more) components 214 in a system such as a transmission system. For example, the heat exchanger 212 may be configured to control the temperature of the fluid supplied to (one or more) components 214 when the prime mover is off and the bidirectional pump is providing fluid to the transmission. Conversely, in some examples, a transmission cooler may be used to control the temperature of the fluid when the prime mover is operating. However, in other examples, the heat exchanger 212 may be positioned at a different location or omitted from the system.

[0071] In the illustrated example, the hydraulic system 200 also includes a pressure relief valve 216 that is in fluid communication with the fluid reservoir 210 via a fluid return line 250. However, in other examples, the pressure relief valve can be omitted from the system. The pressure relief valve 216 can be a hydraulic control valve that is designed to selectively discharge fluid back to the fluid reservoir 210 when the pressure in the hydraulic line 256 is above a threshold. In this way, if desired, an overpressure condition in the hydraulic system 200 that may occur during a cold start can be avoided. In the example shown, the pressure relief valve 216 includes a spring 217 that controls the pressure at which the valve opens. In this way, the pressure relief valve 216 can be passively controlled (e.g., opened and / or closed) to avoid an overpressure condition in the hydraulic circuit 200. However, pressure relief valves with alternative structures have been contemplated.

[0072] As previously described, engagement of the disconnect clutch 206 activates the bidirectional pump 208 by enabling rotational energy to be transferred from a transmission shaft (e.g., a transmission output shaft) to the pump input shaft 244 of the bidirectional pump 208. Rotation of the pump input shaft 244 in turn rotates the bidirectional pump 208, thereby allowing fluid to be drawn from the fluid reservoir 210 and delivered to the component(s) 214 for lubrication.

[0073] The hydraulic system 200 may also include a pressure sensor 262 (eg, a pressure switch) that may be configured to provide feedback to a controller (eg, a transmission control unit) indicating whether the bi-directional pump 208 is disconnected (eg, producing 0 bar) when the prime mover is operating.

[0074] Reference now Figure 3 , shows an example of a power take-off assembly 335 that may be included in the multi-speed transmission 300. However, in alternative embodiments, the power take-off assembly may be included in another suitable system. Figure 3 The power take-off assembly shown can be used with Figure 2 The described power take-off assemblies share at least some similarities.

[0075] The multi-speed transmission 300 includes a housing 302 having a prime mover interface shaft having an interface 306 that is contoured to attach a shaft of a prime mover. In the example shown, the housing 302 includes a plurality of sections 308 and 310 that are attached to each other via fasteners 312 and / or other suitable attachment mechanisms. However, in other examples, other housing contours may be used.

[0076] The multi-speed transmission 300 may also include a fluid reservoir 322 (e.g., a sump) that contains hydraulic fluid, such as oil, for use by other components of the multi-speed transmission 300. The hydraulic fluid may be used for component lubrication and / or component actuation (e.g., clutch actuation). In some examples, the housing 302 at least partially encloses the input assembly, the range clutch assembly, and the multi-speed clutch assembly.

[0077] The power take-off assembly 335 includes a bi-directional pump 324 configured to pump fluid to a hydraulic system. Pressurized fluid from a transmission or other suitable system may enter the power take-off assembly 335 via a supply line 330. Hydraulic fluid may be discharged from the power take-off assembly via a discharge line 338. The bi-directional pump 324 may be configured to draw fluid from a fluid reservoir 322 via a pick-up line 328 when activated and deliver the fluid to a downstream component via an outlet port 332.

[0078] The power take-off housing 337 may at least partially surround and retain components within the power take-off assembly 335. The power take-off housing 337 may be operatively attached to the housing segment 308 using fasteners 336 and / or other suitable attachment means.

[0079] The multi-speed transmission 300 also includes a mechanical output interface portion 314. The output interface 314 can be disposed on one end of the transmission output shaft. The mechanical output interface 314 can be positioned below the electric motor interface. In this way, the transmission can achieve the desired reduction amount. However, other transmission input and output interface arrangements have been considered.

[0080] The multi-speed transmission 300 may also include a pump 316 (e.g., a charge pump). In one example, the pump 316 may be driven by a shaft (e.g., an input shaft) in the multi-speed transmission 300. In one example, the pump 316 is designed to provide pressurized fluid (e.g., oil) to components of the transmission for actuation and / or lubrication, such as clutches, bearings, etc. The pressurized fluid provided by the pump 316 may be delivered toward the power take-off assembly 335 to open the disconnect clutch. The pump may be a suitable type of pump, such as a positive displacement pump. A-A' represents Figure 4-5B The cutting plane of the cross-section view is shown.

[0081] Figure 4 A cross-sectional view of a power take-off assembly 335 coupled to an output shaft 410 of a transmission 300 via a power take-off gear set 400 is shown. The transmission may include an output shaft 410 coupled to other components within the transmission, such as gears, shafts, and / or clutches. However, as previously discussed, the power take-off assembly 335 may be coupled to another suitable shaft in the transmission or incorporated into another suitable system.

[0082] The output shaft 410 may have a mechanical output interface 314 attached thereto or incorporated therein. The mechanical output interface 314 may be contoured to mechanically attach to a downstream driveline component, such as a shaft, joint, etc., that transfers mechanical power to one or more drive axle assemblies. The drive axle assembly may include or be rotatably coupled to a drive wheel of the vehicle such that the wheels rotate when the output shaft rotates, and vice versa. Thus, during operations in which the prime mover is not providing power to the transmission 300, such as during traction operations, the output shaft may rotate due to the rotation of the wheels. This rotation of the output shaft may, in turn, cause rotation of other components of the transmission, such as gears within the drive axle assembly gear set 400 and other shafts and gears of the transmission. In the absence of power from the prime mover, a pump 316, such as a pump 316, that provides fluid to the transmission components, such as a gear set 400, may be provided. Figure 3 The power take-off assembly 335 is designed to provide hydraulic fluid for lubrication and / or other functions during prime mover shutdown to supplement the operation of the charge pump which is not operating during prime mover shutdown.

[0083] The power take-off gear set 400 may include a gear 412 that is directly coupled to the output shaft 410 or formed integrally with the output shaft 410. For example, the gear 412 and the shaft 410 may be manufactured together via machining, casting, a combination thereof, etc. However, in other examples, the gear 412 may be attached to the shaft 410 via a spline connection, via fasteners, a press fit, a combination thereof, etc. The bearing 424 may support and facilitate the rotation of the output shaft 410. In addition, the output shaft 410 may include a spline 425 that facilitates efficient attachment to another section of the output shaft extending from the transmission housing. The bearing 424 may be located in the power take-off housing 337.

[0084] Gear 412 may mesh with gear 414. Gear 414 and other components described herein may be contained within a power take-off housing 337. Gear 414 may be fixedly coupled or integrally formed in shaft 415. Bearings 422 retained in the power take-off housing 337 are coupled to shaft 415 and allow it to rotate. However, in other examples, bearings 422 may be retained in the transmission housing.

[0085] In the example shown, the shaft 415 includes an opening 417 in which an extension 419 of the disconnect clutch 432 is positioned. The extension 419 specifically protrudes axially from a flange 421 including a toothed surface 474. The extension 419 can slide axially within the shaft 415, but can transfer mechanical energy between the clutch and the shaft 415. To achieve this function, the shaft 415 and the extension 419 can each include axially extending splines that cooperate with each other. In this way, the shaft can include internal splines and the extension 419 can include external splines.

[0086] In the example shown, a hydraulic actuator in the form of an actuating piston 423 and a hydraulic chamber 431 is also included in the disconnect clutch 432. The actuating piston 423 protrudes from the flange 421 in an axial direction opposite to the extension 419. The actuating piston 423 cooperates with a recess in the section of the disconnect clutch 432 that includes the flange 429. The flange 429 includes a toothed surface 476 that is designed to engage with the toothed surface 474 and allow torque to be transmitted therethrough when the clutch is engaged.

[0087] Furthermore, in the example shown, a hydraulic chamber 431 is formed in a recess of the clutch segment 427. The hydraulic chamber receives a fluid for clutch actuation, as described herein with respect to Figure 5A and 5B A seal 433 may be disposed around the actuating piston 423 to reduce the chance of fluid leaking from the hydraulic chamber 431 .

[0088] The bearing 420 may be positioned between the clutch section 427 and the section 435 of the power take-off housing 337. In this manner, the disconnect clutch can rotate within the housing. The housing section 435 may be adjacent to (or directly coupled to) the bidirectional pump 324. The bearings 420 may be axially spaced apart to allow a fluid supply passage 436 to extend therebetween and connect with the hydraulic chamber 431.

[0089] The stopper 437 can be retained within the shaft 415, and the spring 441 can be axially limited via the stopper. The stopper 437 allows the spring 441 to be compressed when the disconnect clutch 432 is disengaged. In the example shown, the spring 441 is arranged in the cavity 443 of the extension 419. In this way, the space efficiency of the clutch actuator is improved. However, in other examples, the spring can be positioned outside the extension 419. The seal 439 can circumferentially surround the stopper 437 to reduce the chance of fluid leakage from the clutch.

[0090] The power take-off assembly 335 also includes an electromechanical valve 444 (e.g., a solenoid valve). The electromechanical valve 444 is configured to allow and prevent fluid from flowing from a fluid source 446 to the fluid supply passage 436. The fluid source 446 may be a hydraulic system. Thus, the pressure of the fluid supplied from the fluid source 446 to the valve 444 may be proportional to the pressure of the fluid in the hydraulic system. In detail, the supply line 330 (which is located at Figure 4 4 (shown schematically in FIG. 4 ) fluidly connects a fluid source 446 and a fluid port 461 in the power take-off housing section 435. A fluid passage 452 fluidly connects the port 461 and the electromechanical valve 444. A restriction 453 may be positioned in the fluid passage 452 to increase fluid velocity. A fluid passage 455 fluidly connects the electromechanical valve 444 and the fluid supply passage 436.

[0091] Electromechanical valve 444 allows and prevents fluid flow between fluid passage 452 and fluid passage 455 in response to energization and de-energization of the valve, respectively. In this way, movement of electromechanical valve 444 allows the pressure of fluid delivered to actuating piston 423 in disconnect clutch 432 to be regulated to engage and disengage the clutch, which in turn allows and prevents bidirectional pump 324 from being driven by the rotational input from the transmission.

[0092] Energizing the electromechanical valve 444 blocks the operation of the two-way pump 324, and de-energizing the electromechanical valve 444 allows the operation of the two-way pump. Therefore, during the parking of the vehicle, the power delivered to the electromechanical valve 444 can be automatically interrupted to enable the two-way pump to be reliably rotationally coupled to the transmission during the parking of the vehicle. Therefore, when the vehicle is turned off (parked) but the wheels are rotating, such as during a towing operation, fluid can be supplied to the hydraulic system. Therefore, the possibility of deterioration of the transmission components due to lack of lubrication during towing is avoided. Therefore, the life of the transmission is increased.

[0093] The electromechanical valve 444 may be energized and de-energized via a controller such as a TCU.The methods, control techniques, etc. for a power take-off assembly as expanded herein may be stored in a memory of the controller as instructions executable by a processor of the controller.

[0094] The hydraulic fluid (eg, mineral-based oil and / or synthetic oil) stored in the fluid reservoir 450 (eg, a sump) may be supplied via Figure 4 463, the fluid within the hydraulic system 456 may be directed toward a component 458 of the hydraulic system via one or more fluid lines, conduits, etc., as indicated by arrow 460.

[0095] In the illustrated example, the disconnect clutch 432 is a dog clutch. In detail, the disconnect clutch 432 is a dog clutch having a toothed surface 474 and a toothed surface 476, as described above. The toothed surface 474 is rotationally coupled to the first gear 414, and the toothed surface 476 is rotationally coupled to the input shaft 478 of the two-way pump 324. In this way, during clutch engagement, the cooperation of the toothed surfaces enables rotational energy to be transferred from the power take-off gear set 400 to the two-way pump 324. On the contrary, during clutch disengagement, the toothed surfaces 474 and 476 are spaced apart from each other, thereby preventing the rotational energy transfer between the power take-off gear set 400 and the two-way pump 324. However, in an alternative example, the dog clutch may include a splined interface or may use another suitable type of clutch, such as a friction clutch. However, compared with other types of clutches (such as friction clutches), the dog clutch can exhibit greater space efficiency and reliability.

[0096] The power take-off assembly 335 may be formed as an interconnected unit that can be effectively moved into place and connected to the transmission housing. In detail, the power take-off housing 337 may include fasteners 479 that extend through it and are contoured to be attached to the transmission housing. Therefore, compared to power take-offs attached to other transmission shafts (such as the input shaft or the idler shaft), the power take-off assembly 335 can be efficiently incorporated into the transmission at a later stage of manufacturing. As a result, the manufacturing process achieves greater adaptability, and the power take-off assembly can be used in a wider range of transmissions, thereby increasing customer appeal. However, other power take-off assembly configurations have been envisioned.

[0097] The axes of rotation 490, 491, 492 of the output shaft 410, the shaft 415, and the bi-directional pump 324 are provided for reference, respectively. It should be understood that in the illustrated example, the axes 491 and 492 are coaxially positioned with each other to increase the compactness of the power take-off assembly. However, in alternative examples, the axes 491 and 492 may not be aligned with each other. Furthermore, in the illustrated example, the axis of rotation 490 is parallel to the axes of rotation 491 and 492. However, in alternative examples, these axes may have other suitable orientations.

[0098] Figure 5A and 5B The power take-off assembly 335 is shown in different configurations. Figure 5A Specifically, the disconnect clutch 432 is shown disengaged from the power take-off assembly 335, and Figure 5B Conversely, the power take-off assembly 335 is shown with the disconnect clutch 432 engaged. In this manner, the bidirectional pump 324 can be rotationally decoupled and coupled to the transmission.

[0099] like Figure 5AAs shown, disconnect clutch 432 is disengaged. Clutch disengagement occurs when a prime mover connected to the transmission is operating and a transmission pump (which may be driven by the prime mover) supplies pressurized hydraulic fluid to the transmission.

[0100] Figure 5A The electromechanical valve 444 is shown in an energized state. The electromechanical valve may be energized by the controller when the engine is operating. Specifically, the valve may be energized when the prime mover speed exceeds a threshold, when the prime mover speed has exceeded a threshold for a predetermined duration, or when the output shaft of the prime mover has exceeded a threshold number of revolutions. In this manner, the disconnect clutch is disengaged via the electromechanical valve when there is a high degree of confidence that the transmission is receiving the desired amount of hydraulic fluid from the transmission pump.

[0101] In the energized state, the electromechanical valve 444 allows fluid to flow from the supply line 330 to the fluid supply passage 436 and the hydraulic chamber 431 for disconnecting the clutch 432. In detail, when the pressure of the fluid in the hydraulic chamber 431 applied to the actuating piston 423 is higher than the threshold pressure corresponding to the clutch disengagement, the disconnecting clutch 432 is disengaged. The threshold pressure can be determined by the constant of the spring 441. Specifically, the pressure in the chamber moves the actuating piston 423 in the direction 500 to disengage the toothed surfaces 474 and 476 in the disconnecting clutch. In this way, the spring 441 is in Figure 5A In this way, mechanical power transmission from gear 414 to bidirectional pump input shaft 478 is blocked. Therefore, bidirectional pump 324 is in a compressed state. Figure 5A The hydraulic system 456 is not operating and no fluid flow occurs from the fluid reservoir 450 to the hydraulic system 456.

[0102] on the contrary, Figure 5B The disconnect clutch 432 is shown in an engaged configuration during a period when the prime mover is off. During these conditions, the electromechanical valve 444 is de-energized and prevents fluid from flowing from the supply line 330 to the fluid supply passage 436 and the hydraulic chamber 431 for the disconnect clutch 432. When the hydraulic chamber 431 is depressurized or the fluid pressure drops below a threshold, the spring 441 depressurizes and pushes the toothed surfaces 474 and 476 into engagement. In this way, mechanical power transfer from the gear 414 to the bidirectional pump input shaft 478 is allowed. Therefore, when the transmission is grounded, the bidirectional pump 324 is in Figure 5B is operable, and fluid flow occurs from the fluid reservoir 450 to the hydraulic system 456 and from the hydraulic system to the component 458.

[0103] With the disconnect clutch 432 engaged, rotational torque can be transferred from the gear 414 to the bidirectional pump 324 via the input shaft 478, as described above. Thus, fluid is pumped from the fluid reservoir 450 to the hydraulic system 456 via the bidirectional pump 324. The hydraulic fluid enters the pump via port 462 and leaves the pump via port 463.

[0104] It will be appreciated that due to the configuration of the disconnect clutch hydraulic actuator, the bidirectional pump 324 will continue to provide fluid to the transmission until the charge pump driven by the prime mover generates a hydraulic pressure greater than the threshold. In this way, after the prime mover is started, the bidirectional pump and the lubrication pump can be operated simultaneously for a short duration. However, once the hydraulic pressure exceeds the threshold, the bidirectional pump will be passively disconnected. In this way, the chance of the transmission not receiving the target amount of hydraulic fluid during the prime mover start-up is reduced, thereby increasing the life of the transmission.

[0105] Figure 6 A method 600 for a power take-off assembly and a hydraulic system is depicted. The method 600 occurs when the prime mover transitions from an operating state to an off state. The method 600 may be performed by a power take-off assembly and / or a hydraulic system, such as any of the previously described power take-off assemblies and hydraulic systems or a combination thereof. However, in other examples, the method 600 may be implemented in other suitable power take-off assemblies and / or hydraulic systems. At least a portion of the steps in the method are passively implemented based on hydraulic fluid pressure within the hydraulic system. In detail, steps 602 and 606 are active steps, while step 608 may be a passive action that occurs as a result of the active step 602. Instructions for performing the active steps may be stored as instructions in a memory of a controller, which instructions may be executed by a processor of the controller, as previously described.

[0106] Prior to the start of method 600, the prime mover is in operation. Thus, during operation of the prime mover, pressurized fluid is directed from the hydraulic system to the disconnect clutch in the power take-off assembly. Specifically, when the prime mover is operating, pressurized fluid from the hydraulic system flows through the electromechanical valve and enters the hydraulic chamber of the disconnect clutch hydraulic actuator, thereby maintaining the disconnect clutch disengaged. Disengagement of the disconnect clutch prevents mechanical power from being transmitted from the transmission to the bidirectional pump.

[0107] At 602 , method 600 includes shutting down a prime mover (eg, a traction motor or an internal combustion engine). Method 600 then proceeds to 604 .

[0108] At 604, method 600 includes triggering engagement of the disconnect clutch by reducing pressure applied to an actuating piston of the disconnect clutch to activate a bidirectional pump. When the pressure applied to the piston drops, a toothed interface in the clutch engages due to spring decompression. At 606, the method includes de-energizing an electromechanical valve. De-energizing the electromechanical valve blocks fluid from flowing from the hydraulic system to the hydraulic piston of the clutch, thereby causing the clutch to engage. At 608, the method includes reducing hydraulic system pressure. This pressure drop may occur due to the prime mover being disconnected. Method 600 then proceeds to 606.

[0109] Engagement of the disconnect clutch allows torque to be transferred from the transmission to the bidirectional pump. Thus, when the transmission output shaft is rotating, such as during towing operations where one or more wheels are in contact with the ground, the bidirectional pump pumps fluid from the sump to the hydraulic system of the transmission. In this way, the likelihood of component degradation due to improper lubrication of the components during towing is reduced. As a result, the life of the transmission is increased.

[0110] Figure 7 Another method 700 for operation of a power take-off assembly and hydraulic system is depicted. Method 700 occurs when a prime mover transitions from an off state to an operating state. Method 700 is performed by a power take-off assembly and hydraulic system for implementing method 600. In addition, at least a portion of the steps in method 700 are passively implemented based on fluid pressure within the hydraulic system. In detail, steps 702 and 704 are active steps, while steps 706 and 708 are passive actions that occur as a result of the active steps.

[0111] Prior to the start of method 700, the prime mover is shut off, and therefore, the bi-directional pump in the power take-off assembly delivers fluid to the transmission when the output shaft is rotating (e.g., during towing or when the prime mover is not operating and the vehicle is coasting). Thus, the disconnect clutch is engaged prior to the start of method 700. During the prime mover shut-off period, the hydraulic system pressure is below a threshold for actuating a hydraulic piston in the disconnect clutch.

[0112] At 702, method 700 includes starting the prime mover. Once the prime mover is operated, the fluid pressure in the hydraulic system will increase. At 703, method 700 includes determining whether the electromechanical valve should be energized. This determination can take into account vehicle speed (e.g., transmission speed), the duration of the vehicle speed exceeding the threshold speed, the output shaft revolutions since the starting prime mover, and / or other combinations of operating conditions. For example, when the vehicle speed exceeds the threshold speed (e.g., in a use case example, 3 kilometers per hour), the electromechanical valve can be energized. In other examples, when the vehicle speed has exceeded the threshold value for a threshold duration, the electromechanical valve can be energized. Further, when the output shaft of the prime mover has exceeded the threshold revolutions, the electromechanical valve can be energized.

[0113] If it is determined that the electromechanical valve should not be energized ("NO" at 703), method 700 moves to 704 where the method includes maintaining de-energization of the electromechanical valve.

[0114] Conversely, if it is determined that the electromechanical valve should be energized ("YES" at 703), method 700 moves to 705 where the method includes energizing the electromechanical valve. Energizing the electromechanical valve opens the valve and allows fluid to flow therethrough.

[0115] Next at 706, method 700 includes flowing pressurized fluid through the electromechanical valve to the disconnect clutch to move the clutch piston to initiate disengagement of the disconnect clutch. At 708, method 700 includes deactivating the bidirectional pump in response to the disconnect clutch being disengaged. Thus, the disengagement of the clutch prevents torque from being transferred from the transmission to the bidirectional pump. Method 700 allows the disconnect clutch to be disengaged when the prime mover is operating to avoid efficiency losses when the bidirectional pump is not desired to be used.

[0116] Figure 8 A timing diagram 800 of a use case scenario for a power take-off assembly and a hydraulic system (such as any previously described power take-off assembly and hydraulic system or a combination thereof) is shown. In each figure, time is represented on the abscissa and increases from left to right. The ordinate of curve 802 represents the operating state of the disconnect clutch ("engaged" and "disengaged"). The "engaged" state of the clutch indicates that the clutch allows rotational energy to be transmitted through it, while the "disengaged" state of the clutch indicates that rotational energy is blocked from being transmitted through the clutch. While the clutch is engaged, the bidirectional pump can be driven by torque from the transmission, which can be generated via traction operation or when the prime mover is not operating but coasting. The ordinate of curve 804 represents the operating state of the electromechanical valve ("power on" and "power off"). The ordinate of curve 806 represents the operating state of the prime mover ("operated" and "off"). The ordinate of curve 808 indicates the hydraulic system pressure, wherein the pressure increases from zero toward the arrow along the ordinate.

[0117] At t0, the prime mover is turned off, the disconnect clutch is engaged, the electromechanical valve is de-energized, and the system pressure is zero. At t1, when, for example, the prime mover speed has exceeded the threshold or the prime mover speed has exceeded the threshold for a threshold duration, the prime mover is switched to the operating state and the electromechanical valve is energized between t1 and t2. Between t1 and t2, the system pressure increases. At t2, the fluid pressure exceeds the pressure threshold 810 and the disconnect clutch is switched from the engaged state to the disengaged state. At t3, the prime mover is switched from the operating state to the closed state, and the electromechanical valve is de-energized. The de-energization of the electromechanical valve causes the disconnect clutch to be disengaged between t3 and t4. Alternatively, the disconnect clutch can be disengaged by allowing the system pressure to drop below the threshold pressure 810 at t4 while maintaining the energization of the electromechanical valve.

[0118] The technical effect of the operating method of the power take-off assembly described in this article is to effectively provide hydraulic fluid to the hydraulic system when the prime mover is disconnected (for example, during traction operation) to reduce the chance of transmission system component degradation due to lack of component lubrication, and to provide hydraulic steering and / or clutch actuation functions, thereby improving the reliability and life of the transmission.

[0119] In addition to the schematically depicted components, Figure 3 , 4 , 5A and 5B are drawn approximately to scale, but other relative component sizes may be used in other embodiments.

[0120] Figure 1-5B An example configuration with relative positioning of various components is shown. If shown as directly contacting or directly connected to each other, such elements can be referred to as directly contacting or directly connected, respectively, at least in one example. Similarly, at least in one example, elements shown as continuous or adjacent to each other can be respectively continuous or adjacent to each other. As an example, components placed as face-shared contact with each other can be referred to as face-shared contact. As another example, in at least one example, elements positioned to be spaced apart from each other with only a spacing space between them and no other components can be referred to as such. As another example, elements shown as above / below each other, on opposite sides of each other, or on the left / right of each other can be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the point position of the element can be referred to as the "top" of the component, and the bottommost element or the point position of the element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings and used to describe the positioning of the elements of the accompanying drawings relative to each other. Therefore, in one example, the element shown as above other elements is vertically positioned above the other elements. As yet another example, the shapes of elements depicted in the accompanying drawings may be referred to as having such shapes (e.g., such as circular, linear, planar, curved, rounded, chamfered, angled, etc.). In addition, in one example, elements that are coaxial with each other may be referred to as such. In addition, in at least one example, elements that are shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, elements that are shown as being within another element or outside another element may be referred to as such. In other examples, elements that are offset from each other may be referred to as such.

[0121] The utility model will be further described in the following paragraphs. In one aspect, a power take-off (PTO) assembly is provided, which includes a two-way pump in fluid communication with a fluid reservoir and a hydraulic system; a disconnect clutch configured to mechanically disengage and disconnect the two-way pump from the system when a prime mover is operating; and mechanically engage and connect the two-way pump to the system when the prime mover is off; and an electromechanical valve configured to trigger engagement and disengagement of the disconnect clutch.

[0122] In another aspect, a method for operating a power take-off (PTO) assembly is provided, comprising, during operation of a prime mover, energizing an electromechanical valve to direct fluid from a hydraulic system to a disconnect clutch to maintain disengagement of the disconnect clutch or initiate disengagement of the disconnect clutch and prevent mechanical power transfer between a transmission and a bidirectional pump in fluid communication with the hydraulic system; and during disconnection of the prime mover, preventing fluid from being delivered to the disconnect clutch to transition the disconnect clutch to an engaged position that allows mechanical power transfer between the transmission and the bidirectional pump. In one example, the method may also include de-energizing the electromechanical valve to prevent fluid from being delivered to the disconnect clutch from the hydraulic system. In one example, the method may also include passively reducing the pressure of the fluid delivered to the disconnect clutch to below a threshold to engage the disconnect clutch.

[0123] In yet another example, a power take-off (PTO) assembly is provided that includes: a two-way pump that is fluidly connected to a hydraulic system of a multi-speed transmission; a dog clutch that is used to mechanically connect and disconnect the multi-speed transmission to the two-way pump; and a solenoid valve that allows and blocks fluid flow to an actuating piston in the dog clutch; wherein, when the solenoid valve is energized, fluid is allowed to flow to the actuating piston, and when the pressure of the fluid applied to the actuating piston is above a threshold, the actuating piston disengages from the dog clutch; and wherein, when the solenoid valve is de-energized, fluid flow to the actuating piston is blocked and the actuating piston engages the dog clutch.

[0124] In any of these aspects or combinations of these aspects, the electromechanical valve may be a solenoid valve that causes the disconnect clutch to mechanically disengage when energized and causes the disconnect clutch to mechanically engage when de-energized.

[0125] In any of these aspects or combinations of these aspects, the power take-off assembly may further include a fluid supply line in fluid communication with the solenoid valve and the hydraulic system.

[0126] In any of these aspects or combinations of these aspects, the disconnect clutch can include a first toothed surface coupled to a first gear meshing with a second gear coupled to an output shaft including an output interface.

[0127] In any of these aspects or combinations of these aspects, the disconnect clutch can include a second toothed surface coupled to a shaft in the bi-directional pump.

[0128] In any of these aspects or combinations of these aspects, the bi-directional pump may be in fluid communication with one or more lubricated components.

[0129] In any of these aspects or combinations of these aspects, the prime mover can be an internal combustion engine.

[0130] In any of these aspects or combinations of these aspects, the system can be a multi-speed transmission including two or more clutches.

[0131] In any of these aspects or combinations of these aspects, the bi-directional pump may be in fluid communication with one or more lubricated components.

[0132] In any of these aspects or combinations of these aspects, the actuation piston can engage the dog clutch when the solenoid valve is energized and a pressure of fluid applied to the actuation piston is less than a threshold.

[0133] In any of these aspects or combinations of these aspects, the dog clutch may include a spring that is compressed when the dog clutch is disengaged.

[0134] In any of these aspects or combinations of these aspects, the bi-directional pump may be in fluid communication with a sump in the multi-speed transmission.

[0135] In any of these aspects or combinations of these aspects, the dog clutch can include a first toothed surface rotationally coupled to a gear in the multi-speed transmission.

[0136] In any of these aspects or combinations of these aspects, the multi-speed transmission can be driven by a traction motor.

[0137] In any of these aspects or combinations of these aspects, the disconnect clutch includes a first toothed surface coupled to a first gear meshing with a second gear coupled to an output shaft including an output interface.

[0138] In another representation, a ground-driven hydraulic power take-off system is provided that includes a solenoid valve that actively holds a clutch in a disengaged configuration when energized, wherein the clutch is directly rotationally coupled to a hydraulic pump that feeds hydraulic fluid to one or more system components when receiving rotational input from the clutch, and wherein the clutch is configured to receive rotational input from a shaft and / or gear in the system.

[0139] In any of these aspects or combinations of these aspects, the solenoid valve can allow the clutch to return to the engaged configuration when de-energized.

[0140] It should be noted that the example control and estimation routines included herein can be used with various system (e.g., powertrain) configurations. The control methods and routines disclosed herein can be stored in non-transitory memory as executable instructions and can be executed by a control system including a controller combined with various sensors and actuators, and other system hardware combined with an electronic controller. Therefore, the actions, operations and / or functions described can graphically represent the code in the non-transitory memory of a computer-readable storage medium that will be programmed into a vehicle, powertrain, and / or transmission control system. The various actions, operations and / or functions shown can be performed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order for implementing the features and advantages of the examples described herein is not necessary, but is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the actions, operations and / or functions shown can be repeatedly performed. If desired, one or more method steps described herein can be omitted.

[0141] Although various embodiments have been described above, it should be understood that they are presented as examples rather than limitations. It will be apparent to those skilled in the relevant art that the disclosed subject matter may be implemented in other specific forms without departing from the spirit of the subject matter. Therefore, the above-described embodiments are considered to be illustrative and not restrictive in all respects. Therefore, the configurations and routines disclosed herein are exemplary in nature, and these specific examples should not be considered restrictive, as many variations are possible. For example, the above-described technology can be applied to a powertrain including different types of propulsion sources, including different types of electric motors and / or internal combustion engines and different systems. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein and other features, functions and / or characteristics.

[0142] As used herein, unless otherwise indicated, the term "about" is interpreted to mean plus or minus five percent of the range.

[0143] The appended claims particularly point out certain combinations and subcombinations believed to be novel and non-obvious. These claims may refer to "an" element or a "first" element or the equivalent thereof. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or characteristics may be claimed in this or a related application by amendment of the present claims or by presentation of new claims. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are deemed to be included in the subject matter of the present disclosure.

Claims

1. A power take-off assembly, characterized in that: include: a bidirectional pump in fluid communication with the fluid reservoir and the hydraulic system; A disconnect clutch, the disconnect clutch being configured to: mechanically disengaging and disconnecting the bidirectional pump from the system when the prime mover is operating; and mechanically engaging and connecting the bidirectional pump to the system when the prime mover is turned off; as well as An electromechanical valve is configured to trigger engagement and disengagement of the disconnect clutch.

2. The power take-off assembly according to claim 1, characterized in that: The electromechanical valve is a solenoid valve, wherein: When energized, causing mechanical disengagement of said disconnect clutch; and When power is removed, mechanical engagement of the disconnect clutch results.

3. The power take-off assembly according to claim 2, characterized in that: Also included is a fluid supply line in fluid communication with the solenoid valve and the hydraulic system.

4. The power take-off assembly according to claim 1, characterized in that: The disconnect clutch includes a first toothed surface coupled to a first gear meshing with a second gear coupled to an output shaft including an output interface.

5. The power take-off assembly according to claim 4, characterized in that: The disconnect clutch includes a second toothed surface coupled to a shaft in the bidirectional pump.

6. The power take-off assembly according to claim 1, characterized in that: The bi-directional pump is in fluid communication with one or more lubricated components.

7. The power take-off assembly according to claim 1, characterized in that: The prime mover is an internal combustion engine.

8. The power take-off assembly according to claim 1, characterized in that: The prime mover is an electric motor.

9. The power take-off assembly according to claim 1, characterized in that: The system is a multi-speed transmission including two or more clutches.

10. The power take-off assembly according to claim 9, characterized in that: The bidirectional pump is in fluid communication with a sump in the multi-speed transmission.

11. The power take-off assembly according to claim 10, characterized in that: The disconnect clutch includes a first toothed surface rotationally coupled to a gear in the multi-speed transmission; The fluid is oil; and / or The multi-speed transmission is driven by a traction motor.

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