Patent Description:
The present invention relates generally to a lubricant supported electric motor. More specifically, the present invention relates to a lubricant supported electric motor with at least one monitoring port for improving the operating characteristics and performance of the lubricant supported electric motor.

This section provides a general summary of background information and the comments and examples provided in this section are not necessarily prior art to the present invention.

Various drivelines in automotive, truck, and certain off-highway applications take power from a central prime mover and distribute the power to the wheels using mechanical devices such as transmissions, transaxles, propeller shafts, and live axles. These configurations work well when the prime mover can be bulky or heavy, such as, for example, various internal combustion engines ("ICE"). However, more attention is being directed towards alternative arrangements of prime movers that provide improved environmental performance, eliminate mechanical driveline components, and result in a lighter-weight vehicle with more space for passengers and payload.

"On wheel", "in-wheel" or "near-wheel" motor configurations are one alternative arrangement for the traditional ICE prime mover that distributes the prime mover function to each or some of the plurality of wheels via one or more motors disposed on, within, or proximate to the plurality of wheels. For example, in one instance, a traction motor, using a central shaft though a rotor and rolling element bearings to support the rotor, can be utilized as the "on wheel", "in wheel" or "near wheel" motor configuration. In another instance, a lubricant supported electric motor, such as described in U. Application Serial No. <NUM>/<NUM>,<NUM>, can be utilized as the "on wheel", "in wheel" or "near wheel" motor configuration. While each of these motor configurations result in a smaller size and lighter weight arrangement as compared to the prime movers based on the internal combustion engine, they each have certain drawbacks and disadvantages.

For example, the utilization of traction motors as the "on wheel", "in wheel" or "near wheel" configuration still results in motors that are too heavy and not robust enough to shock loading to be useful for wheel-end applications. In other words, present traction motors are large, heavy structures supported by rolling element bearings, which are too heavy and large to be practical for wheel end applications. Similarly, the utilization of a lubricant supported electric motors as the "on wheel", "in wheel" or "near wheel" motor in an automotive or land vehicle application results in an arrangement with some performance issues when it is subjected to the wide range of dynamic forces encountered during operation at the wide range of speeds encountered in a prime-mover application. Present arrangements of lubricant supported electric motors are not robust enough, and thus not designed to perform well under all the conditions and dynamic forces encountered in a wheel-end motor arrangement. Additionally, present arrangements of lubricant supported electric motors in "on-wheel" applications are static and very conservatively designed systems that have very limited performance measurements, and thus have higher bearing friction/shear loss and shorter life. Accordingly, a need remains for an improved lubricant supported electric motor which provides improved operating characteristics in real-time. <CIT> relates to electric motors with lubricant support between a rotor and stator of the electric motor.

The subject invention is generally directed to a lubricant supported electric motor that includes a stator and a rotor movably disposed within the stator. The stator presents an outer raceway and the rotor presents an inner raceway disposed in spaced relationship with the outer raceway to define at least one hydrostatic support chamber disposed therebetween. A lubricant is disposed in the at least one hydrostatic support chamber for supporting the rotor within the stator. A monitoring port is disposed in fluid communication with the at least one hydrostatic support chamber, and a sensor is coupled with the monitoring port for monitoring an operating characteristic of the lubricant or the hydrostatic support chamber. The monitored operating characteristic is analyzed to determine an operating condition of the lubricant supported electric motor in real time, such as the detection of lubricant supply faults, unstable motor operation, or other real-time diagnostics and prognostics. The lubricant supported electric motor with a monitoring port and sensor is also light and small, and thus contributes to the overall design strategy for eliminating weight and size from automobiles and land vehicles. Other advantages will be appreciated in view of the following more detailed description of the subject invention.

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention as defined in the appended claims.

Example embodiments of a lubricant supported electric motor in accordance with the present invention will now be more fully described. Each of these example embodiments are provided so that this invention is thorough and fully conveys the scope of the inventive concepts, features and advantages to those skilled in the art. To this end, numerous specific details are set forth such as examples of specific components, devices and mechanisms associated with the lubricant supported electric motor to provide a thorough understanding of each of the embodiments associated with the present invention. However, as will be apparent to those skilled in the art, not all specific details described herein need to be employed, the example embodiments may be embodied in many different forms, and thus should not be construed or interpreted to limit the scope of the inventior as defined in the appended claims.

<FIG> illustrate a lubricant supported electric motor <NUM> in accordance with an aspect of the invention. As best illustrated in <FIG>, the lubricant supported electric motor <NUM> includes a stator <NUM> and a rotor <NUM> extending along an axis A and movably (i.e., rotatably) disposed within the stator <NUM> to define a gap <NUM> (also shown as "G" in <FIG>) therebetween. In an alternative arrangement which is not a part of the present invention, the stator <NUM> and the rotor <NUM> can be reversed, with the stator <NUM> extending along the axis A and the rotor <NUM> rotatably disposed around the stator <NUM>. A lubricant <NUM> is disposed in the gap <NUM> for supporting the rotor <NUM> within the stator <NUM>, and providing continuous contact between these components. The lubricant <NUM> may therefore act as a buffer (e.g., suspension) between the stator <NUM> and the rotor <NUM> minimizing or preventing contact therebetween. In other words, the lubricant <NUM> prevents direct contact between the stator <NUM> and rotor <NUM> and provides an electric lubricant supported motor <NUM> which is robust to shock and vibration loading due to the presence of the lubricant <NUM>. Additionally, and alternatively, a substantially incompressible lubricant <NUM> may be used in order to minimize the gap between the stator <NUM> and rotor <NUM>.

As further illustrated <FIG>, the stator <NUM> defines a passageway <NUM> disposed in fluid communication with the gap <NUM> for introducing the lubricant <NUM>. However, the passageway <NUM> could be provided on any other components of the lubricant supported electric motor <NUM> without departing from the subject invention as defined in the appended claims. According to an aspect, the lubricant <NUM> may be cycled or pumped through the passageway <NUM> and into the gap <NUM> in various ways. For example, a high pressure source (e.g., a pump) <NUM> of the lubricant <NUM> may be fluidly coupled to a low pressure source (e.g., a sump) <NUM> of the lubricant <NUM>, where the lubricant <NUM> may move from the high pressure source to the lower pressure source, through the passageway <NUM> and into the gap <NUM>. Rotation of the rotor <NUM> relative to the stator <NUM> may operate as a self-pump to drive lubricant <NUM> through the passageway <NUM> and into the gap <NUM>.

As further illustrated in <FIG>, the rotor <NUM> is interconnected to a drive assembly <NUM> for coupling the lubricant supported electric motor <NUM> to one of the plurality of wheels of a vehicle. For example, in one instance, the drive assembly <NUM> may include a planetary gear system. Alternatively, the drive assembly <NUM> may include one or more parallel axis gears. The stator <NUM> and rotor <NUM> are configured to exert an electromagnetic force therebetween to convert electrical energy into mechanical energy, moving the rotor <NUM> and ultimately driving the wheel coupled to the lubricant supported electric motor <NUM> via the drive assembly <NUM>. The drive assemblies <NUM> may provide one or more reduction ratios between the lubricant supported electric motor <NUM> and the wheel in response to movement of the rotor <NUM>.

As best illustrated in <FIG>, the rotor <NUM> presents an inner raceway <NUM> and the stator <NUM> presents an outer raceway <NUM>. The inner and outer raceways <NUM>, <NUM> collectively define at least one hydrostatic support chamber <NUM> which is established by a portion of the gap <NUM> and receives the lubricant <NUM> for supporting the rotor <NUM> within the stator <NUM>. For example, the hydrostatic support chamber <NUM> which is established in the gap <NUM> between the inner and outer raceways <NUM>, <NUM> determines a dynamic pressure developed when the lubricant supported electric motor <NUM> is in hydrodynamic mode. The gap <NUM> between the inner and outer raceways <NUM>, <NUM> also determines the pressure in the hydrostatic support chamber <NUM> when the lubricant supported electric motor <NUM> is in hydrostatic mode. In a preferred embodiment, the at least one hydrostatic support chamber <NUM> includes a plurality of hydrostatic support chambers <NUM> spaced circumferentially around and between the stator <NUM> and the rotor <NUM> and which each have their individualized pressure in the hydrodynamic and hydrostatic modes. For example, as illustrated in <FIG>, in a preferred arrangement, the at least one hydrostatic support chamber <NUM> can include four hydrostatic support chambers <NUM> circumferentially spaced from one another around the axis A. However, any number of hydrostatic support chambers <NUM> can be utilized without departing from the scope of the invention as defined in the appended claims. As further illustrated in <FIG>, the stator <NUM> defines a plurality of passageways <NUM> each disposed in fluid communication with a respective one of the hydrostatic support chambers <NUM> for supplying lubricant thereto.

As further illustrated in <FIG>, the lubricant supported electric motor <NUM> includes a monitoring port <NUM> disposed in fluid communication with each hydrostatic support chamber <NUM>. A sensor <NUM> is coupled to the monitoring port <NUM> for sensing the operating characteristic of the lubricant <NUM> disposed within the at least one hydrostatic support chamber <NUM>. For example, the sensor <NUM> can be a pressure sensor configured to sense a pressure of the lubricant <NUM> disposed within the at least one hydrostatic support chamber <NUM>. However, the sensor <NUM> could also be comprised of other sensors <NUM>, such as a temperature sensor for sensing a temperature of the lubricant <NUM> or a viscosity sensor for sensing a viscosity of the lubricant, without departing from the scope of the invention as defined in the appended claims.

As further illustrated in <FIG>, when the at least one hydrostatic support chamber <NUM> includes a plurality of hydrostatic support chambers <NUM>, a monitoring port <NUM> and sensor <NUM> can be disposed in communication with each hydrostatic support chamber <NUM>. In other words, in a preferred arrangement, each hydrostatic support chamber <NUM> includes its own respective monitoring port <NUM> and sensor <NUM> for providing individualized monitoring of the plurality of hydrostatic support chambers <NUM>. The utilization of the monitoring port <NUM> and the sensor <NUM> advantageously improves the performance of the lubricant supported electric motor <NUM> by providing the ability to detect operating characteristics of the lubricant <NUM> disposed within each of the hydrostatic support chambers <NUM>, which is used and analyzed to detect certain operating characteristics of the lubricant supported electric motor <NUM> such as oil supply faults, stable or instable motor operation, as well as others. In other words, the monitoring port <NUM> and the sensor <NUM> facilitates real-time diagnostics and prognostics for the lubricant supported electric motor <NUM>.

As illustrated in <FIG>, each sensor <NUM> is preferably electrically connected to a controller <NUM> for sending the monitored operating characteristic of the lubricant <NUM> and/or hydrostatic support chamber <NUM> to the controller <NUM> for further evaluation to determine the operating characteristic of the lubricant supported electric motor <NUM> and provide the real-time diagnostics and prognostics. For example, the operating characteristics (e.g., pressure, temperature, viscosity) sensed by the plurality of sensors <NUM> can be used by the controller <NUM> to:.

In an embodiment, the controller <NUM> is also disposed in communication with a component of the lubricant supported electric motor <NUM> and can use the monitored characteristic of the lubricant <NUM> and/or hydrostatic support chamber <NUM> in conjunction with other measured parameters of the lubricant supported electric motor <NUM> (e.g., motor speed, motor temperature, central oil supply pressure, etc.) to provide further diagnostics and prognostics of the lubricant supported electric motor <NUM>.

The incorporation of monitoring port <NUM> and sensor <NUM> advantageously provides for optimized performance and operating characteristics for the lubricant supported electric motor <NUM> in real-time. In other words, the monitoring port <NUM> and sensor <NUM> allows for the monitoring and diagnosing of the motor's performance in real-time using, for example, pressure measurements of the lubricant <NUM> in the hydrostatic support chamber <NUM>. This improved monitoring of the motor's performance ultimately leads to better overall performance of the lubricant supported electric motor <NUM> compared to its static and very conservatively designed counterparts.

Claim 1:
A lubricant supported electric motor (<NUM>) comprising:
a stator (<NUM>) presenting an outer raceway (<NUM>);
a rotor (<NUM>) extending along an axis (A) and rotatably disposed within said stator (<NUM>);
said rotor (<NUM>) presenting an inner raceway (<NUM>) disposed in spaced relationship with said outer raceway (<NUM>) to define at least one hydrostatic support chamber (<NUM>) therebetween;
a lubricant (<NUM>) disposed in said hydrostatic support chamber (<NUM>) for supporting said rotor (<NUM>) within said stator (<NUM>),
characterized by:
a monitoring port (<NUM>) disposed in fluid communication with said at least one hydrostatic support chamber (<NUM>); and
a sensor (<NUM>) coupled with said monitoring port (<NUM>) for monitoring an operating characteristic of said lubricant (<NUM>) disposed in said at least one hydrostatic support chamber (<NUM>) for use in determining a real-time operating condition of the lubricant supported electric motor (<NUM>).