Lubrication system with a flow regulating floater container

A system and method for lubrication system are provided. The lubrication system includes a floater container including a floater compartment that contains a buoyant floater, where the floater container is coupled to a housing bulkhead and where the floater container includes an inlet opening in a first wall that is off-axis from a horizontal plane and forms an angle with a second wall. Further, the housing bulkhead includes an outlet opening positioned lower than the inlet opening and provides fluidic communication between the floater compartment and a rotating component compartment that contains a rotating component.

TECHNICAL FIELD

The present disclosure relates to a lubrication system with a floater for regulating a lubrication level in a sump.

BACKGROUND AND SUMMARY

Inside mechanical devices, such as mechanical transmissions, lubricants, such as oils are used to decrease friction and dissipate heat within the devices to enhance device operation. Splash lubrication has been used in certain mechanical systems due to their relative simplicity and higher resistance to component degradation when compared to more complex lubrication systems.

EP 1602861 A1 to Matsufuji et al. discloses a transmission with a chamber containing a ring gear partially submerged in oil. The baffle plate that partially surrounds a rotating shaft and hold lubricant therein. The ring gear functions to drive splash lubrication which decreases friction in the system's components as well as cools the components. To circulate oil through the ring gear chamber, an orifice is provided which directs the oil to another chamber in the system.

The inventors have recognized several drawbacks not only with Matsufuji's transmission but other lubrication systems. Matsufuji's transmission may have churning losses which are too high for certain vehicle designs. For instance, electrified vehicle platforms may demand decreased transmission power losses to increase battery life and vehicle range while decreasing down-times. Further, prior oil regulating devices may not function as desired when the system is tilted, leading to low lubrication levels and causing component wear and decreased system longevity.

The inventors have recognized the aforementioned issues and developed a lubrication system to at least partially overcome the issues. The lubrication system includes a floater container and a floater compartment containing a buoyant floater. In the lubrication system, the floater container is coupled to a housing bulkhead and includes an inlet opening in a first wall that is off-axis from a horizontal plane and forms an angle with a second wall. Further in the system, the housing bulkhead includes an outlet opening positioned lower than the inlet opening and provides fluidic communication between the floater compartment and a rotating component compartment. Designing a floater container with these features allows the flowrate of lubricant entering the rotating component compartment to be passively regulated over a wider variety of operating conditions when compared to previous oil regulating mechanisms. Specifically, positioning the inlet opening on the off-axis wall allows for desired lubricant regulation when the system is tilted.

Further in one example, to allow for a desired lubricant flow regulation, the floater container and the buoyant floater may be configured to operate in an open position and a closed position. In the closed position, the buoyant floater inhibits a flow of lubricant through the inlet opening into the floater compartment of the floater container, and in the open position, the buoyant floater is spaced away from the inlet opening. In such an example, the position of the buoyant floater changes as a lubricant level in the floater compartment varies. In this way, the flowrate of lubricant into the rotating component compartment is precisely regulated to allow the rotating component to achieve an intended amount of lubricant that decreases component wear and removes heat therefrom without unduly increasing churning losses.

DETAILED DESCRIPTION

A lubrication system is described herein that includes a floater assembly which strategically and passively controls an amount of lubricant delivered to a compartment that contains a gear or other suitable rotating component to strike a desired balance between gear lubrication and churning losses. The floater assembly controls the lubricant flow to the compartment over a wide range of system inclinations. As such, floater assembly functionality may be maintained over a wider operating window, which decreases the likelihood of an undesirable amount of lubricant within the gear enclosure which can cause churning losses if the level is too high or component wear if the level is too low. The sustained lubricant regulating functionality during tilting may be particularly desirable in vehicles and particularly electric vehicles. However, the lubrication system described herein is capable of usage in a variety of systems. To achieve the passive lubricant regulating functionality, the system includes a floater container with two walls that are angled with regard to a horizontal axis and constrain movement of a buoyant floater. One of these walls may include an opening that may be positioned higher than an opening in a bulkhead. The buoyant floater selectively blocks the opening in the wall to provide desired lubricant flow regulation which maintain the flowrate of lubricant through the other opening at a target flowrate or within a target flowrate range. Consequently, the lubricant around the gear can be maintained at a desired level or within a desired range that strikes a balance between gear lubrication and churning losses, if wanted. Further, the floater assembly may be efficient to manufacture and install in the transmission or other suitable system.

FIG.1shows an example of a lubrication system100. The lubrication system100may, in one example, be included in a gearbox102of a transmission104. In turn, the transmission104may be included in a vehicle106such as an electric vehicle (EV) or an internal combustion engine (ICE) vehicle. In the EV example, the vehicle may be an all-electric vehicle or a hybrid electric vehicle. However, the lubrication system100may be used in other locations in the vehicle such as the axle or in entirely other operating environments such as in stationary machines. For instance, the lubrication system may be used in power plants, in other embodiments.

The lubrication system100includes a floater container108coupled to a housing bulkhead110. The bulkhead110divides a rotating component compartment112from a calmer compartment114. The rotating component compartment112and the calmer compartment114may form a sump115in the system. Thus, the calmer compartment may function as a lubricant reservoir and therefore be referred to as a reservoir or a source compartment for a buoyant floater compartment, which is elaborated upon herein. However, the sump may include other compartments in one example or solely include one of the aforementioned compartments, in another example. The bulkhead110includes a surface111in the calmer compartment114and a surface113in the rotating component compartment112. Further, a top side117of the bulkhead110is positioned below the shaft118in the illustrated example.

In the illustrated example, the floater container108is coupled to the housing bulkhead110. However, in other examples, the floater container108may be integrally formed with the housing bulkhead110. The floater container108may be cast, machined into the transmission housing, or manufactured as a part of another component. As such, the bulkhead110may be used as a support surface for the floater container and/or for closing (e.g., bounding) the internal volume of the floater compartment. Attaching the floater container108to the housing bulkhead110enables system assembly to be efficiently carried out.

The lubrication system100may further include a housing116that forms at least a portion of the boundary of the calmer compartment114. The bulkhead110is included in the housing116in the illustrated examples and therefore may be referred to as a housing bulkhead.

In the illustrated example, a shaft118is supported in the housing via bearings for example. However, other housing and shaft arrangements may be used in alternate examples. For instance, the shaft may pass through the housing in an unsupported manner.

A gear120or other suitable rotating component rotates on the shaft118. The gear120includes teeth122that may mesh with teeth on another gear to enable mechanical power transfer between the gears. The teeth may be straight cut, helical cut, etc.

The floater container108may be coupled to the bulkhead110via attachment devices (e.g., bolts, screws, and the like), welds, combinations thereof, and the like. For instance, flanges402in the floater container108include openings that receive attachment devices, in the illustrated example. However, other suitable attachment techniques may be used to attach the floater container to the bulkhead, in other examples.

The floater container108includes a conduit124that extends vertically along the bulkhead110, in the illustrated example. The conduit124provide fluidic communication between an area above a fluid level in the calmer compartment114and an internal floater compartment204in the floater container shown and expanded upon herein with regard toFIGS.2-8. The lubricant in the floater compartment may have greater turbulence than the lubricant in the calmer compartment114. The conduit124allows the lubricant in the calmer compartment114, the internal floater compartment204, shown inFIG.2, and the rotating component compartment112to see the same air reference pressure. In other examples, the conduit may be omitted from the floater container and the container may be coupled to a tube or other conduit may enable the internal floater compartment and the calmer compartment to see a similar air pressure.

An axis system is provided inFIG.1as well asFIGS.2-10, for reference. The z-axis may be a vertical axis (e.g., parallel to a gravitational axis), the x-axis may be a lateral axis (e.g., horizontal axis), and/or the y-axis may be a longitudinal axis, in one example. However, the axes may have other orientations, in other examples.

The transmission104may include a control system190with a controller192as shown inFIG.1. The controller192may include a microcomputer with components such as a processor193(e.g., a microprocessor unit), input/output ports, an electronic storage medium194for executable programs and calibration values (e.g., a read-only memory chip, random access memory, keep alive memory, a data bus, and the like). The storage medium may be programmed with computer readable data representing instructions executable by a processor for performing the methods and control techniques described herein as well as other variants that are anticipated but not specifically listed.

The controller192may receive various signals from sensors195coupled to various regions of the transmission104. Upon receiving the signals from the various sensors195ofFIG.1, the controller192processes the received signals, and employs various actuators196of system and/or transmission components to adjust the components based on the received signals and instructions stored on the memory of controller192. For example, the controller192may send a command to a component140which drives rotation of an input of the transmission such as an electric motor. In response, the motor may drive rotation of the transmission's input and subsequently the gear120. The other controllable components in the vehicle may function in a similar manner with regard to sensor signals, control commands, and actuator adjustment, for example. An input device197(e.g., an accelerator pedal, a brake pedal, a gear selector, combinations thereof, and the like) may be in electronic communication with the controller192.

FIGS.2-7show different view of the floater container108. As shown inFIG.2the floater container108includes an inlet opening200in a first wall202. The inlet opening200extends through the first wall202and provides fluidic communication between the interior floater compartment204and the calmer compartment114, shown inFIG.1, when the opening isn't blocked by a buoyant floater206. However, as shown inFIG.2, the buoyant floater206blocks the inlet opening200, thereby inhibiting fluidic communication through the inlet opening200. Consequently, when the floater blocks the opening lubricant is prevented from flowing from the calmer compartment to the floater compartment204. An internal surface (e.g., planar surface) of the first wall202along with other internal surfaces in the internal floater compartment204are profiled to constrain movement of the buoyant floater206and cause the floater to block the inlet opening200when the lubricant level in the compartment is greater than a threshold level and permit lubricant flow through the opening when the lubricant level drops below the threshold level. The profile of the surfaces in the floater compartment are expanded upon herein with regard toFIGS.7-8.

The conduit124is again shown inFIG.2. When the floater compartment204is coupled to the bulkhead110, shown inFIG.1, an air flow channel208is formed. The air flow channel208includes an upper opening210that opens into the calmer compartment114, shown inFIG.1, when installed. The air flow channel208extends in a vertical direction to allow the internal floater compartment204and the calmer compartment114to see the same air pressure. Consequently, the maximum flowrate into the rotating component compartment112(for splash lubrication) is defined by a diameter800of an outlet opening802in the bulkhead110(discussed in greater detail herein and shown inFIG.8) opening the output hole diameter and the maximum lubricant level that can be reached in the internal floater compartment204of the floater container108before the floater206closes the inlet opening200.FIG.2further shows a lateral side300of the container and one of the flanges402which include attachment device openings which enable attachment to the bulkhead110, shown inFIG.1. However, as previously indicated, the container may be coupled to the bulkhead using other suitable techniques, such as welding or integrally forming the container in the bulkhead via machining, casting, and the like.

FIG.3shows a first side view of the floater container108. A lateral side300and a lower wall302of the container are illustrated. The lower wall302forms an angle304with a lateral axis306. Angling the lower wall in this manner allows the interior floater compartment of the container to achieve a desired volume and profile which allows the floater to move away from the opening200during certain conditions but not block the outlet opening802in the bulkhead110, shown inFIG.8and discussed in greater detail herein. The conduit124is again shown and extends from an upper wall308in the floater container. Further, a front wall310of the floater container108is depicted.

FIG.4shows a front view of the floater container108. The conduit124is again shown along with the lateral side300and an opposing lateral side400. Flanges402with attachment device openings may be used to attach the container to the bulkhead110, shown inFIG.1.

The floater container108further includes the first wall202and a second wall404which are angled (with regard to a horizontal axis) and abut one another. As such, the first wall202forms an angle406with a horizontal axis407and the second wall404forms an angle408with the horizontal axis which may be equivalent to one another. The inlet opening200is positioned in the first wall202. Arranging the first and second walls202and404in this manner in relation to the surface111of the bulkhead110, shown inFIG.1, allows the walls to guide the buoyant floater into a blocking position for the inlet opening200when the lubricant level within the interior floater compartment of the container is above a threshold level and allows the inlet opening200to be blocked when the floater container108(and the system more generally) is tilted. Consequently, a desired lubricant flowrate or range of flowrates into the rotating component compartment is maintained over a wide range of system operating conditions.

FIG.5shows the lateral side400of the floater container108as well as the conduit124. The lower wall302, the upper wall308, the front wall310, and the second wall404of the container is further shown inFIG.5.

FIG.6shows a top view of the floater container108with the first wall202, the second wall404, and the inlet opening200. The conduit124is further shown inFIG.6.

FIG.7shows a rear view of the floater container108with a buoyant floater206contained therein. The first wall202and the second wall404are again shown. Interior surfaces700and702of the first and second walls202and404, respectively are additionally illustrated. The surfaces700and702may be planar to enable the floater to be guided into and out of a position that blocks the inlet opening200to be smoothly achieved. It will be understood, that a portion of the surface111of the bulkhead110, shown inFIG.2, forms another boundary of the interior floater compartment204and enables the guidance of the buoyant floater206into and out of the position which blocks the inlet opening200. Therefore, as the lubricant level in the interior floater compartment varies, the floater206is pushed into and out of a position which blocks the inlet opening200. In this way the floater compartment is refilled with lubricant. The floater functionality with regard to lubricant flow through the inlet opening is expanded upon herein with regard toFIG.8. The surfaces700and702abut at section704which may be arranged at or near an uppermost portion706of the interior floater compartment204. In this way, the floater206is restrained in a section of the compartment when the lubricant in the compartment is above a threshold level.

FIG.8shows a cross-sectional view of the lubrication system100. The floater container108, the buoyant floater206, the gear120, the rotating component compartment112, calmer compartment114, and housing bulkhead110are again illustrated.

The calmer compartment114includes a lubricant level804which is higher than the inlet opening200. The lubricant level804is higher than the inlet opening but lower than the upper opening210in the conduit124, shown inFIG.7.

The inlet opening200in the floater container108and the outlet opening802in the bulkhead110are further illustrated. The lubricant level806within the internal floater compartment204dictates the vertical position (along an axis parallel to the z-axis) of the buoyant floater206. The lubricant level806is a threshold lubricant level that trigger blocking of the inlet opening200via the buoyant floater206due to the buoyancy of the floater pushing the floater into sealing engagement with the inlet opening200. When the floater206blocks the inlet opening lubricant flow from the calmer compartment114to the floater compartment204is inhibited. The height of the lubricant in the floater compartment204(along with the diameter800of the outlet opening802) dictates the flowrate of lubricant through the outlet opening due to the free surfaces of the lubricant in the calmer compartment114, the floater compartment204, and the rotating component compartment112being exposed to a similar reference air pressure.

When the lubricant level in the floater compartment204drops below the threshold level806, lubricant flows through the inlet opening200and refills lubricant in the compartment until the floater again reaches the height which blocks the inlet opening. During both conditions (when the inlet opening is blocked and open) lubricant flows through the outlet opening802(e.g., housing bulkhead opening) into the rotating component compartment112. A lubricant level808in the rotating component compartment112is further illustrated inFIG.8. Rotation of the gear120or other suitable rotating component then drives splash lubrication in the rotating component compartment. The splash lubricant may either be returned to the calmer compartment114or flow back to the lower portion of the rotating component compartment. In this way, the lubricant in the rotating component compartment is turbulent while lubricant in the calmer compartment where some of the splash lubricant is collected has less bulk motion.

The interior surface700of the first wall202, the interior surface702of the second wall404shown inFIG.7, and the surface111of the bulkhead110constrain movement of the floater and guided it through desired blocking and unblocking cycles. Furthermore, one or more of the aforementioned surfaces may be planar to precisely guide the floater in a desired direction as the lubricant level changes.

A diameter810of the floater206, illustrated inFIG.10, may be between 30 millimeters (mm) and 40 mm, in one example. Sizing the floater in this manner allows the floater to achieve a desired buoyancy to seal the inlet port while being small enough to be reasonably installed in a gearbox or other suitable mechanical system without interfering with component therein. However, the floater may have a different diameter, in other examples. The size of the floater may be selected based on factors such as the type of lubricant used in the system, the material construction of the floater, the expected operating air pressure in the system, and the like.FIG.10again shows the floater206in the interior floater compartment204of the floater container108along with the opening200in the floater container as well as the conduit124in the floater container.

A width812(front to rear) of the interior floater compartment204, shown inFIG.8, is greater than the diameter810of the buoyant floater206, shown inFIG.10, to allow the floater to move away from the inlet opening200when the lubricant level falls.

Further, the surfaces that surround the floater compartment204may be designed to reduce the likelihood (e.g., avoid) locking of the floater in the compartment due to floater expansion and/or other reasons. To elaborate, the floater206, in the upper position, is located by three planes (the surfaces700,702and the bulkhead surface111, shown inFIG.1). Considering the cone tangent to the three planes, the aperture of the cone inhibits the floater from self-locking in the cone. To elaborate, the cone's aperture angle may be >20°. Further, to reduce the likelihood of floater locking, the diameter of the floater may be significantly less than the dimensions of the surfaces that bound the interior compartment of the floater container such as the surfaces700,702and the portion of the bulkhead surface that demarcates the interior compartment.

FIGS.9A and9Bdepict an exemplary floater container900with a buoyant floater902that blocks an inlet opening904due to the lubricant level906in the floater compartment204. It will be appreciated that the floater container900and the buoyant floater902may exhibit at least some structural and functional features that are similar to floater container108and the buoyant floater206depicted inFIGS.1-8. Repeated description of these features is omitted for concision.FIG.9Aspecifically shows the floater container900at an upright position andFIG.9Bshows the container at a tilted position with the container forming an angle908with a vertical axis910. As shown, the floater206blocks the inlet opening904in both the upright position and the tilted position. Walls912and914which abut one another and guide movement of the floater902into and out of a blocking position are further illustrated inFIGS.9A and9B. Interior surfaces (e.g., planar surfaces)916and918of the walls912and914respectively are further illustrated. The floater compartment may be profiled to maintain the floater in sealing contact with the inlet opening when the compartment is tiled in a range between 0° and 90° minus the angle associated with the semi-aperture of the cone, in one example. To elaborate, the range may be between 0° and 70°, in one specific example.

FIGS.1-9Bprovide for a method for operation of a lubrication system. The method includes rotating a gear on a shaft. In such an example, a portion of the gear is submerged in lubricant that is contained in a gear compartment and a level of the lubricant contained in the gear compartment is controlled via passive metering of lubricant through a housing bulkhead opening that provides fluidic communication between the gear compartment and a floater compartment of a floater container.

The technical effect of the lubrication system operating method described herein is to efficiently provide a desired amount of lubricant to a gear via a system with a construction with a low likelihood of component degradation and simplified installation.

FIGS.1-8and10are drawn approximately to scale aside from the schematically illustrated components. Although other relative component dimensions may be used, in other embodiments.

The invention will be further described in the following paragraphs. In one aspect, a lubrication system is provided that comprises a floater container including a floater compartment that contains a buoyant floater; wherein the floater container is coupled to a housing bulkhead; wherein the floater container includes an inlet opening in a first wall that is off-axis from a horizontal plane and forms an angle with a second wall; and wherein the housing bulkhead includes an outlet opening positioned lower than the inlet opening and provides fluidic communication between the floater compartment and a rotating component compartment that contains a rotating component.

In another aspect, a method for operation of a lubrication system is provided that comprises rotating a gear on a shaft; wherein a portion of the gear is submerged in lubricant that is contained in a gear compartment; wherein a level of the lubricant contained in the gear compartment is controlled via passive metering of lubricant through a housing bulkhead opening that provides fluidic communication between the gear compartment and a floater compartment of a floater container; and wherein the floater container includes a buoyant floater contained in an interior compartment that selectively blocks a container opening that provides fluidic communication between a compartment and the floater compartment.

In another aspect, a lubrication system in a gearbox of a transmission is provided that comprises a calmer compartment with a lubricant therein; and a floater container containing a buoyant floater in a floater compartment; wherein the floater compartment and the buoyant floater passively regulate an amount of lubricant flowing from the floater compartment to a gear compartment through an outlet opening of a housing bulkhead; and wherein the floater compartment includes an inlet opening in a first wall that is angled in relation to a horizontal plane and abuts a second wall that is angled in relation to the horizontal plane.

In any of the aspects or combinations of the aspects, the housing bulkhead may include a first side that is coupled to the floater container and define a portion of the boundary of the floater compartment; and a second side that forms a portion of the boundary of a rotating component compartment; and wherein the housing bulkhead divides a calmer compartment from the rotating component compartment.

In any of the aspects or combinations of the aspects, the floater container and the buoyant floater may be configured to operate in an open position and a closed position, in a closed position the buoyant floater inhibits a flow of lubricant through the inlet opening into the floater compartment of the floater container and in an open position, the buoyant floater is spaced away from the inlet opening, wherein the position of the buoyant floater changes as a lubricant level in the floater compartment varies.

In any of the aspects or combinations of the aspects, the inlet opening may be positioned below a top of the floater compartment.

In any of the aspects or combinations of the aspects, the floater container may be configured to inhibit a hydrostatic head in the floater compartment from falling below a threshold value.

In any of the aspects or combinations of the aspects, an external surface in the housing bulkhead may abut the first wall and the second wall in the floater compartment.

In any of the aspects or combinations of the aspects, the lubrication system may further comprise a conduit extending vertically from the floater compartment and including an opening that is positioned above a lubricant level in the calmer compartment and profiled to provide fluidic communication between an interior of the floater compartment and the calmer compartment.

In any of the aspects or combinations of the aspects, the conduit may extend toward a shaft on which the rotating component rotates during operation.

In any of the aspects or combinations of the aspects, the floater container may include a lower wall sloping toward the housing bulkhead.

In any of the aspects or combinations of the aspects, a housing bulkhead of the calmer compartment may include at least one bearing that is coupled to a shaft on which the rotating component rotates.

In any of the aspects or combinations of the aspects, the floater may have a diameter between 30 millimeters (mm) and 40 mm.

In any of the aspects or combinations of the aspects, the lubrication system may be included in a gearbox and the rotating component is a gear.

In any of the aspects or combinations of the aspects, the floater container may include a conduit which extending vertically and including an opening that is positioned above a lubricant level in the calmer compartment and profiled to provide fluidic communication between an interior of the floater compartment and the calmer compartment.

In any of the aspects or combinations of the aspects, when a lubricant level is above a threshold value, the buoyant floater may block the inlet opening.

In any of the aspects or combinations of the aspects, the air pressure in the floater compartment, the calmer compartment, and the container may be substantially equal.

In any of the aspects or combinations of the aspects, the first wall and the second wall may be planar.

In any of the aspects or combinations of the aspects, the floater compartment may be coupled to the housing bulkhead.

In any of the aspects or combinations of the aspects, the inlet opening may be blocked when the floater compartment is tilted in a range between 0° and 85° from vertical.

In another representation, a passive floater assembly is provided that comprises a case that contains a floating device and includes angled walls, wherein the floating device blocks an inlet in one of the angled walls when oil in the interior of the container is above a threshold value and the passive floater assembly is tilted.

Note that the example control and estimation routines included herein can be used with various powertrain and/or other system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other system hardware in combination with the electronic controller. As such, the described actions, operations, and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the system.

While various embodiments have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant arts that the disclosed subject matter may be embodied in other specific forms without departing from the spirit of the subject matter. The embodiments described above are therefore to be considered in all respects as illustrative, not restrictive. As such, the configurations disclosed herein are exemplary in nature, and that these specific examples are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to transmissions or other mechanical systems in which lubrication is desired. In the transmission example, the powertrain may include different types of propulsion sources including different types of electric machines and/or internal combustion engines. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.