Gear cooling system

Abstract

Gear cooling system, which includes: a spray tube located in a central opening contained within a first gear; wherein the spray tube contains an oil outlet; wherein the oil outlet is arranged within a first section with a smaller diameter of the central opening; wherein the first section with a smaller diameter is axially offset from an outer toothed section of the first gear; and wherein the central opening has a section of larger diameter which is arranged within the outer toothed section of the first gear.

Description

TECHNICAL FIELD

[0001] The present description generally relates to a gear cooling system. More specifically, the present disclosure relates to a gear cooling system that directs oil internally through a gear. BACKGROUND AND SUMMARY

[0002] Gears in electric drivetrains, such as electric axles, and other energy-intensive applications can have a high thermal value due to the mechanical stresses and friction generated during operation. Attempts have been made in various systems to cool gears using external oil lubrication and air cooling. However, these cooling systems cannot meet the cooling requirements in certain systems. Furthermore, the inventors recognized the difficulties of designing a rotating system to withstand high rotational forces and speeds while effectively distributing the oil and cooling the gears within the system.

[0003] The problems described above can be solved by a gear cooling system. In one example, the gear cooling system includes a spray tube located in a central opening contained in a gear. The spray tube includes an oil outlet located in a smaller diameter portion of the central opening. Furthermore, the smaller diameter portion is axially offset from an outer toothed portion of the gear, and the central opening includes a larger diameter portion disposed within the outer toothed portion of the gear. During system operation, the oil flows from the spray tube into the smaller diameter portion, and centrifugal forces cause the oil to flow from the smaller diameter portion to the larger diameter portion.In this way, the gear is effectively cooled from the inside, which increases the longevity of the gear by reducing the risk of gear damage caused by high temperatures.

[0004] Additionally, in one example, the smaller-diameter portion may include multiple oil passages formed as recesses in an inner surface. These oil passages allow a larger amount of oil to flow through the central opening, thereby improving gear cooling.

[0005] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. Short description of the characters Fig. Figure 1 shows an illustration of a gear cooling system in an electric axle of a vehicle. Fig. 2 shows a cross-sectional view of an example of a gear cooling system with a spray tube arranged in a central opening of a gear. Fig. 3 shows a gear cooling system with screw channels in a central opening of a gear. Detailed description

[0006] The following description refers to a gear cooling system for a vehicle or other suitable operating environment requiring gear cooling. The vehicle, such as the vehicle from Fig. 1, may include a gear transmission with one or more shafts and one or more gears. The gear transmission includes a gear cooling system, such as the gear cooling system in Fig. 2. An oil source may supply oil to a spray tube, which in turn may direct oil to a central opening in a shaft and a gear. As the gear rotates, the oil flows through portions of the central opening and exits the central opening before being returned to the oil source. In this way, the gear is cooled from within via the oil. In some examples, the gear cooling system may include one or more screw channels, such as the screw channels of Fig. 3. These screw channels allow the oil to flow more quickly through the central opening of the gear cooling system.

[0007] In Fig. 1 shows a vehicle 100. It is understood that the vehicle 100 is in Fig. 1 is for illustrative purposes only and is a non-limiting example of how a vehicle may be configured. Other examples may include variations in the arrangement and positioning of vehicle components that are not Fig. 1, as well as additional components shown in Fig. 1 are not shown. In the illustrated example, the vehicle 100 is a fully electric vehicle (EV), such as a battery electric vehicle (BEV). In other examples, the vehicle 100 may be a hybrid electric vehicle (HEV) with an internal combustion engine. Further, in some examples, the vehicle 100 may be powered solely by an internal combustion engine. In such an example, the engine may be rotatably coupled to a geared transmission 106, which is described in more detail herein. The vehicle 100 may be a passenger car, a commercial vehicle, an on-road vehicle, or an off-road vehicle, with various examples.

[0008] In the illustrated example, the vehicle 100 includes an electric axle 102. In some examples, the electric axle 102 may be a front or rear axle. The electric axle 102 may include a traction motor 104, the gear train 106, and a differential 108. For example, the traction motor 104, the gear train 106, and the differential 108 may be housed in a single housing. An inverter 110 may also be incorporated into the electric axle housing. In other examples, however, the vehicle may also be equipped with an electric drive that is spaced apart from the axle 102 but supplies it with mechanical power.

[0009] The traction motor 104 may include a rotor that electromagnetically interacts with a stator to drive rotation of a rotor shaft contained within the rotor. The traction motor 104 may also include a housing, bearings coupled to the rotor shaft, and the like.

[0010] The traction motor 104 may be a multi-phase alternating current (AC) motor, and as such, in some examples, the traction motor may be electrically connected to the inverter 110 via an electrical connection (e.g., multi-phase busbars, wires, and the like). The inverter 110 is configured to convert direct current (DC) to alternating current (AC) and vice versa. In other examples, the inverter 110 may be omitted from the vehicle 100, and the traction motor may be a DC motor.

[0011] The inverter 110 may be electrically coupled to an energy storage device 112 (e.g., one or more traction batteries, capacitors, combinations thereof, and the like). A direct current electrical connection may be established between the inverter 110 and the energy storage device 112.

[0012] In some examples, the traction motor 104 may be a motor-generator capable of converting electrical energy into mechanical energy and vice versa. Thus, the traction motor 104 may be electrically coupled to the energy storage device 112 (e.g., via the inverter 110) to both draw power from the energy storage device and generate electrical energy to be stored in the energy storage device. Furthermore, if the vehicle 100 is a hybrid vehicle, the energy storage device 112 may be charged by an internal combustion engine.

[0013] The traction motor 104 is rotatably coupled (e.g., directly rotatably coupled) to a shaft in the gear train 106. The rotatable coupling between the traction motor 104 and the gear train 106 may be via a splined connection, a sleeve, bolted flanges, combinations thereof, and the like. As such, the gear train 106 is configured to receive torque from the traction motor 104. In some examples, the gear train 106 may be a single-speed transmission. In other examples, the gear train 106 may be a multi-speed transmission with clutches for shifting between various active gears.

[0014] The gear train 106 includes a housing and gears that can rotate and mesh with each other to transfer mechanical energy (e.g., rotational energy). During operation of the gear train, heat is generated within the gear train.

[0015] To dissipate heat from the gear train 106, a gear cooling system 150 is provided. It should be understood that the gear cooling system 150 and the other gear cooling systems described herein may also be used in other systems requiring gear cooling. The gear cooling system(s) may be used, for example, in industrial machinery, agricultural equipment, etc. The gear cooling system 150 directs oil internally through a gear 152 to dissipate heat therefrom. The gear cooling system therefore increases the longevity of the gear train by reducing the risk of gear wear. Thus, the gear cooling system 150 may, in particular, be an internal cooling system for the gear. The gear cooling system 150 receives oil from an oil source 154. In one particular example, the oil source 154 may include a pump within an oil reservoir (e.g., an oil pan).This means that the sump can be housed in a lower section of a housing of the electric axle. However, in other examples, other suitable oil sources can also be used. The oil source can, for example, be a gravity-fed system.

[0016] The gear train 106 can transmit torque to the axle shafts 114, 116 via the differential 108. The gear train 106 can be rotatably coupled to the differential 108 via one or more shafts, gears, joints, combinations thereof, and the like.

[0017] For example, the differential 108 can be rotatably coupled to the gear transmission 106 to deliver torque to the axle shafts 114, 116. In this way, the gear transmission 106 can transmit the torque delivered by the traction motor 104 via the differential 108 or the axle shafts 114, 116 to the drive wheels 118, 120 to enable the vehicle to move.

[0018] The vehicle 100 may additionally include an axle 132 and wheels 134, 136. In one example, the axle 132 may be a non-driven axle. However, in other examples, the axle 132 may also be a drive axle, which may be driven, for example, by an electric drive and / or an internal combustion engine. More specifically, in one specific example, the axle 132 may be an electric axle. Thus, in certain embodiments, the vehicle may be equipped with all-wheel drive.

[0019] The vehicle 100 may further include a control system 124 including a controller 126, sensors 128, and actuators 130. The controller 126 may be a microcomputer, including components such as a microprocessor unit, input / output ports, an electronic storage medium for executable programs and calibration values, e.g., a read-only memory chip, random access memory, diagnostic memory, and a data bus. In one example, the controller 126 may be a powertrain control module (PCM).

[0020] The controller 126 may receive various signals from sensors 128 coupled to various areas of the vehicle 100. For example, the sensors 128 may include position sensors coupled to the transmission 106, engine sensors for monitoring engine speed, temperature, mass air flow, etc., sensors coupled to the energy storage device 112 for measuring the battery state of charge and temperature, and sensors coupled to the traction motor 104 for monitoring the status of the traction motor. After receiving the signals from one or more of the sensors 128 Fig. 1, the controller 126 processes the received signals and uses one or more of the actuators 130 of the vehicle 100 to adjust the operation of the engine and transmission based on the received signals and the instructions stored in the memory of the controller 126.

[0021] Fig. 1-3 contain a Cartesian coordinate system for orienting the views. In one example, the y-axis can be a vertical axis (e.g., parallel to a gravity axis), the x-axis can be a longitudinal axis (e.g., a horizontal axis), and / or the z-axis can be a lateral axis. However, in other examples, the axes can have other orientations.

[0022] Fig. 2 shows a gear cooling system 200 for a gear 204 that includes an extension 202. In some examples, the gear cooling system 200 may be arranged in an electrical axis, such as the electrical axis 102 of Fig. 1. In other examples, the gear cooling system may be disposed within an electric drivetrain that includes an electric drive spaced from, but powering, the drive axle, or another system that includes gears as previously mentioned.

[0023] The gear 204 includes an outer toothed section 206 and the extension 202. In the example shown, the extension 202 contains no teeth. However, other gear profiles are also possible.

[0024] In some examples, gear 204 and extension 202 may be fabricated as a monolithic component. In other examples, gear 204 may be located on extension 202 and connected to the shaft by welding, press fitting, combinations thereof, and the like. Gear 204 includes outer toothed portion 206 with gear teeth 207. Gear teeth 207 are helical gears in the illustrated example. However, other types of gear teeth, such as spur gears, may be used in other examples.

[0025] The extension 202 has an outer diameter D1. The gear 204 has an outer diameter D2. The outer diameter D2 of the gear 204 can be larger than the outer diameter D1 of the extension 202.

[0026] A land 214 may extend outwardly (e.g., away from the rotation axis 208) from the outer surface 210 of the extension 202. The land 214 may be disposed near, but spaced apart from, the outer toothed portion 206 of the gear 204.

[0027] The gear cooling system 200 includes a central opening 216 located within the extension 202 and the gear 204. The central opening 216 and the extension 202 may extend along the rotational axis 208. Furthermore, the boundary of the central opening may include interior surfaces of the extension.

[0028] Furthermore, a spray tube 218 may be positioned in the central opening 216. The spray tube 218 may be cylindrical, with a longitudinal axis parallel to the rotational axis 208 of the gear cooling system 200. However, other spray tube profiles are also contemplated. In the example shown, the spray tube 218 receives oil from an oil source 219, which is schematically shown in Fig. 2. The arrow 221 indicates the oil flow from the oil source 219 to the spray tube 218, which can occur via lines, valves, and the like. The oil source 219 can, for example, be a pump located in a sump of an electric axle. That is, the oil pump can be integrated into an oil circuit that branches out to supply the spray tube with oil, and into another electric axle branch that supplies other devices in the axle with oil. In this way, the space efficiency of the electric axle can be increased, if desired. The oil circuit can, for example, supply bearings, clutch(es), and / or other components requiring oil with oil via nozzles, lines, and the like.In other examples, the oil source and spray tube described herein may be an oil circuit independent of another oil circuit in the electric axis that supplies oil to oil-demanding components such as clutches, bearings, and the like. However, other suitable oil sources are also contemplated. In one example, spray tube 218 may be relatively stationary while gear 204 rotates. However, in other examples, spray tube 218 and gear 204 may rotate together.

[0029] The outer diameter D3 of the spray tube 218 is smaller than the inner diameters of the extension 202 and the gear 204, so that a channel 223 is formed between the spray tube and the inner surfaces of the shaft and the gear. The spray tube 218 contains an oil outlet 220 through which the oil from the spray tube flows into the central opening 216. The oil in the spray tube may be under pressure. Heat transfer to the oil in the central opening 216 occurs via the gear 204, which meshes with another gear 217, which Fig. 2 is shown schematically.

[0030] The central opening 216 includes a first smaller diameter section 222 and a larger diameter section 224. The central opening 216 may further include a second smaller diameter section 226, the larger diameter section being disposed between the first smaller diameter section and the second smaller diameter section. In the illustrated example, the first smaller diameter section 222 is axially offset from the outer toothed section 206 relative to the rotation axis 208. However, in other examples, the first smaller diameter section may be positioned at another suitable location in the gear. The oil outlet 220 is disposed within the first smaller diameter section 222 in the illustrated example such that oil from the spray tube 218 is sprayed through the oil outlet and into the first smaller diameter section.

[0031] The larger diameter portion 224 may be disposed adjacent to the first smaller diameter portion 222 and within the outer toothed portion 206 of the gear 204. Thus, the first smaller diameter portion 222 and the larger diameter portion 224 may be fluidly connected, and oil may flow directly from the first smaller diameter portion into the larger diameter portion.

[0032] The second smaller-diameter portion 226 may be axially offset from the outer toothed portion 206 on a second side relative to the rotational axis 208. Furthermore, the second smaller-diameter portion 226 may be disposed adjacent to the larger-diameter portion 224. In this way, oil from the larger-diameter portion 224 may flow directly into the second smaller-diameter portion 226.

[0033] The first smaller diameter section 222 has a diameter D4 that is larger than the outer diameter D3 of the spray tube 218. The larger diameter section 224 has a diameter D5 that is larger than the diameter D4 of the first smaller diameter section 222. The larger diameter section 224 may have a constant diameter over the entire axial length of the larger diameter section relative to the rotation axis 208.

[0034] The diameter D4 of the first smaller-diameter section 222 can be constant over the axial length of the first smaller-diameter section. The diameter D5 of the larger-diameter section 224 can also be constant over the axial length of the larger-diameter section. Furthermore, the axial length L1 of the larger-diameter section 224 can be greater than the axial length L2 of the first smaller-diameter section 222. In this way, the desired dynamics of the oil flow in the channel 223 are achieved to improve cooling of the gear. However, other contours of the central opening 216 are also contemplated.

[0035] As the gear 204 rotates, the oil in the central opening 216 is forced outward (e.g., into the inner surface of the extension 202) by centrifugal forces. Thus, the centrifugal forces cause the oil to spread along the inner surface of the extension 202. Due to the different diameters, the oil flows across the interface between the first smaller diameter section 222 and the larger diameter section 224 into the larger diameter section. In addition, an internal land 227 can ensure that a larger amount of oil is retained in the first smaller diameter section 222. Thus, the rotation of the extension 202 allows the oil to flow passively from the first smaller diameter section 222 to the larger diameter section 224. This creates a space-saving oil cooling arrangement that can be less complex than external gear cooling systems.

[0036] The second smaller diameter section 226 may have a diameter D6 that is smaller than the diameter D5 of the larger diameter section 224 and larger than the diameter D4 of the first smaller diameter section 222. Because the diameter D6 of the second smaller diameter section 226 is smaller than the diameter D5 of the larger diameter section 224, the oil pools in the larger diameter section before it can enter the second smaller diameter section. For example, the second smaller diameter section 226 may form a wall that forces the oil to pool (e.g., converge) in a portion of the central opening located inside the outer toothed section 206 of the gear 204. Because the oil pools (e.g.,converges), more heat can be transferred from the gear 204 into the oil, increasing the ability of the gear cooling system 200 to cool the gear 204. Additionally, the pooled oil can flow from the larger diameter section 224 into the second smaller diameter section 226 because the diameter D6 of the second smaller diameter section is larger than the diameter D4 of the first smaller diameter section. The centrifugal forces created by the rotation of the extension 202 and the gear 204 push the oil into the second smaller diameter section 226 before the oil has accumulated enough to re-enter the first smaller diameter section 222.

[0037] Arrows 228 indicate the general direction of oil flow through gear cooling system 200 in the example shown. Oil supplied from oil source 219 (see arrow 221) flows through spray tube 218 to oil outlet 220. A portion of the oil exits spray tube 218 via oil outlet 220 and enters the first smaller diameter section 222 of central opening 216. Centrifugal forces generated by the rotation of gear 204 push the oil from the first smaller diameter section 222 into the larger diameter section 224, as shown by arrows 228. Once the oil has accumulated in the larger diameter section 224, a portion of the oil flows from the larger diameter section into the second smaller diameter section 226. The oil then exits the second smaller diameter section 226.

[0038] After the oil exits the second, smaller-diameter section 226, the oil can be recirculated (e.g., via a sump and pump) and recirculated to the central opening 216 via the spray tube 218. In some examples, the gear cooling system 200 can also supply oil to other components in the gear train. This means that the oil exiting the gear can be directed to an oil sump and reused for cooling and lubrication, or, for example, can be routed directly to other gear sets.

[0039] Fig. 3 shows a gear cooling system 300 which has some similarities to the gear cooling system 200 of Fig. 2. Therefore, overlapping components of the gear cooling system 300 and the gear cooling system 200 are numbered similarly, and the description of the overlapping components is omitted for brevity. For example, the gear cooling system 300 includes the gear 204 with the extension 202, the central opening 216, the larger diameter section 224, and the second smaller diameter section 226. It is understood that the gear cooling system 300 may also include a spray tube (e.g., the spray tube 218 of Fig. 2) which is arranged within the central opening 216 and includes an oil outlet which opens into a first section of smaller diameter 302. However, the spray tube has been shown in the illustration of the gear cooling system 300 in Fig. 3 is omitted in order to make the contours of the sections of the central opening 216 visible.

[0040] In the illustrated example, the central opening 216 of the gear cooling system 300 includes the first smaller diameter section 302, the larger diameter section 224, and the second smaller diameter section 226, with the larger diameter section being located between the first smaller diameter section and the second smaller diameter section. The first smaller diameter section 302 may be axially offset from the gear 204 on a first side relative to the rotation axis 208.

[0041] As in Fig. As shown in Figure 3, an inner surface 304 of the first smaller-diameter portion 302 may include channels 306 shaped to direct oil to the larger-diameter portion 224 as the extension 202 rotates. That is, the channels 306 may be spiral-shaped. Thus, the channels 306 allow a greater amount of oil to flow between the first smaller-diameter portion 302 and the larger-diameter portion 224, further improving gear cooling.

[0042] Fig. Figures 1-3 show a method for operating a gear cooling system. The method involves directing oil from an oil source to a spray tube. For example, a pump located within an oil reservoir (e.g., an oil pan) may drive the oil flow from the reservoir to the spray tube. The method may further include rotating the gear in which the spray tube is positioned. The rotation of the gear passively drives the oil flow through the central opening of the gear, thus cooling the gear. Consequently, the performance of the gear transmission is improved.

[0043] Fig. 2-3 are drawn approximately to scale, except for the schematically illustrated components. However, in other embodiments, the components may have different relative dimensions.

[0044] Fig. 1-3 show example configurations with the relative arrangement of the various components. When these elements are in direct contact with each other or are directly coupled, they may be referred to as being in direct contact or directly coupled, respectively, at least in one example. Similarly, elements shown side by side or adjacent to each other may be adjacent to each other or adjacent to each other, at least in one example. For example, components that are in surface-to-surface contact with each other may be referred to as being in surface-to-surface contact. As another example, in at least one instance, elements that are separated from each other with only a space between them and that do not have any other components may be referred to as such.In yet another example, elements depicted above / below, on opposite sides, or to the left / right of each other may be referred to as such, relative to each other. Further, in at least one example, as depicted in the figures, a topmost element or point of an element may be referred to as a "top" of the component, and a bottommost element or point of the element may be referred to as a "bottom" of the component. As used herein, the terms top / bottom, upper / lower, above / below may refer to a vertical axis of the figures and may be used to describe the positioning of elements of the figures relative to each other. Thus, in one example, elements displayed above other elements are arranged vertically above the other elements.As another example, the shapes of the elements depicted in the figures may be referred to as such (e.g., circular, straight, flat, curved, rounded, beveled, angled, or the like). Furthermore, in at least one example, depicted elements that intersect each other may be referred to as intersecting elements or as intersecting elements. Furthermore, an element depicted inside another element or outside another element may be referred to as such.

[0045] The invention is further described in the following paragraphs. In one aspect, a gear cooling system is provided including a spray tube positioned within a central opening contained in a first gear, the spray tube including an oil outlet, the oil outlet being positioned within a first smaller diameter portion of the central opening, the first smaller diameter portion being axially offset from an outer toothed portion of the first gear, and the central opening including a larger diameter portion positioned within the outer toothed portion of the first gear.

[0046] In another aspect, a method of operating a gear cooling system is provided, including directing oil to a spray tube from an oil source and rotating a gear. The gear cooling system includes the spray tube disposed within a central opening of the gear and including an oil outlet, the oil outlet being disposed within a first smaller diameter portion of the central opening, the first smaller diameter portion being axially offset from an outer toothed portion of the gear, and the central opening including a larger diameter portion disposed within the outer toothed portion of the gear.

[0047] In another aspect, an internal gear cooling system is provided that includes a spray tube positioned within a central opening in a gear, the spray tube including an oil outlet, the oil outlet being positioned within a first smaller diameter portion of the central opening, the first smaller diameter portion being axially offset from an outer toothed portion of the gear, the central opening including a larger diameter portion disposed within the outer toothed portion of the gear, the central opening further including a second smaller diameter portion disposed at an axial end of the gear and within the outer toothed portion of the gear, and oil flowing sequentially through the first smaller diameter portion, the larger diameter portion, and the second smaller diameter portion.

[0048] In any one or combination of aspects, the central opening may further include a second smaller diameter portion disposed at an axial end of the first gear and within the outer toothed portion of the first gear.

[0049] In any one of the aspects or combinations of the aspects, a diameter of the second smaller diameter portion may be greater than a diameter of the first smaller diameter portion.

[0050] In one of the aspects or combinations of the aspects, the spray tube may be in fluid communication with an oil source.

[0051] In one of the aspects or combinations of the aspects, the oil source may be an oil pump disposed in a sump of an electric drive.

[0052] In one of the aspects or combinations of the aspects, a diameter of the first smaller diameter portion may be constant over its axial length.

[0053] In one of the aspects or combinations of the aspects, an axial length of the larger diameter portion may be greater than an axial length of the first smaller diameter portion.

[0054] In one of the aspects or combinations of the aspects, an axial length of the spray tube may be greater than an axial length of the first gear.

[0055] In one of the aspects or combinations of the aspects, a diameter of the larger diameter portion may be constant over its axial length.

[0056] In one of the aspects or combinations of the aspects, the outer toothed portion may be formed from a plurality of helical teeth.

[0057] In any one of the aspects or combinations of the aspects, the gear cooling system may be included in an electric axle that includes a traction motor, a differential, and a plurality of axle shafts.

[0058] In any one of the aspects or combinations of the aspects, the electric axle may be included in a fully electric vehicle.

[0059] In one of the aspects or combinations of the aspects, the first gear can mesh with a second gear.

[0060] In any one of the aspects or combinations of the aspects, the first smaller diameter portion may include a plurality of oil passages formed as depressions in an inner surface.

[0061] In any one or combination of aspects, the central opening may further include a second smaller diameter portion disposed at an axial end of the gear and within the outer toothed portion of the gear, and the oil may exit the gear cooling system through the second smaller diameter portion.

[0062] In one of the aspects or combinations of the aspects, the internal cooling system for the gear may be included in a gear transmission of an electric axle.

[0063] In any one of the aspects or combinations of the aspects, the first smaller diameter section may include a plurality of spiral oil passages.

[0064] It should be noted that the example control and estimation routines contained herein can be used with various engine, powertrain, and / or vehicle system configurations. Furthermore, the control routines may also be employed in other systems involving gears, such as industrial machinery. The control methods and routines disclosed herein may be stored as executable instructions in non-volatile memory and executed by the control system, including the controller, in combination with the various sensors, actuators, and other system hardware. The specific routines described herein may represent one or more arbitrary processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like.Thus, the various actions, operations, and / or functions illustrated may be performed in the order shown, in parallel, or in some cases, without them. Accordingly, the order of processing is not required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for convenience of illustration and description. One or more of the illustrated actions, operations, and / or functions may be performed repeatedly depending on the strategy employed.Furthermore, the described actions, operations, and / or functions may graphically represent code to be programmed into the non-volatile memory of the computer-readable storage medium in the control system, wherein the described actions are performed by executing the instructions in a system including the various hardware components in combination with the electronic controller.

[0065] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not intended to be limiting, as numerous variations are possible. Unless expressly stated otherwise, the terms "first," "second," "third," etc., are not intended to denote an order, position, quantity, or importance, but are used merely to distinguish the individual elements. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0066] Fig. 2-3 are drawn approximately to scale, except for the schematically illustrated components. However, in other embodiments, the components may have different relative dimensions.

[0067] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion 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 properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure.

Claims

[1] Gear cooling system, which includes: a spray tube located in a central opening contained in a first gear; wherein the spray tube includes an oil outlet; wherein the oil outlet is disposed within a first smaller diameter portion of the central opening; wherein the first smaller diameter portion is axially offset from an outer toothed portion of the first gear; and wherein the central opening has a larger diameter portion disposed within the outer toothed portion of the first gear. [2] The gear cooling system of claim 1, wherein the central opening further includes a second smaller diameter portion disposed at an axial end of the first gear and within the outer toothed portion of the first gear. [3] The gear cooling system of claim 2, wherein a diameter of the second smaller diameter portion is larger than a diameter of the first smaller diameter portion. [4] A gear cooling system according to any one of the preceding claims, wherein the spray tube is in fluid communication with an oil source. [5] Gear cooling system according to claim 4, wherein the oil source is an oil pump arranged in a sump of an electric drive. [6] A gear cooling system according to any one of the preceding claims, wherein the diameter of the first smaller diameter portion is constant over its axial length. [7] A gear cooling system according to any one of the preceding claims, wherein an axial length of the larger diameter portion is greater than an axial length of the first smaller diameter portion. [8] Gear cooling system according to one of the preceding claims, wherein an axial length of the spray tube is greater than an axial length of the first gear. [9] A gear cooling system according to any one of the preceding claims, wherein the diameter of the larger diameter portion is constant over its axial length. [10] Gear cooling system according to one of the preceding claims, wherein the outer toothed portion is formed from a plurality of helical teeth. [11] A gear cooling system according to any one of the preceding claims, wherein the gear cooling system is included in an electric axle including a traction motor, a differential and a plurality of axle shafts, and wherein the electric axle is included in a fully electric vehicle. [12] Gear cooling system according to one of the preceding claims, wherein the first gear meshes with a second gear. [13] A gear cooling system according to any one of the preceding claims, wherein the first smaller diameter portion includes a plurality of oil channels formed as recesses in an inner surface.

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