Integrated electrical auxiliary oil pump

An externally mounted electric fluid pump for pumping fluid within a power transmission device is disclosed. The pump includes a housing adapted to be mounted to an external surface of the power transmission device. The pump is positioned within the housing and includes an input member. An electric motor is positioned within the housing and drives the input member. A controller is positioned within the housing to control the electric motor and vary the output of the pump.

FIELD

The present disclosure generally relates to fluid pumps. More particularly, an integrated electric auxiliary oil pump for an automobile is described.

BACKGROUND

Many automatic transmissions, engines, transfer cases and other power transferring devices are equipped with internal oil pumps for lubrication or other pressurized fluid supply. Internal oil pumps are typically continuously driven by a rotating member of the vehicle powertrain. While this arrangement is fairly simple to construct, continuously driving the pump may not be the most efficient way of operating the vehicle. During certain modes of vehicle operation, the input shaft driving the pump may rotate at relatively high speed thereby producing relatively high fluid flow at a time when relatively low or no fluid flow is required. The energy to drive the pump during these modes of operation is not providing value and may be considered inefficient waste.

Additionally, many of the previously known pumps are sealed within cavities formed by the engine or transmission housings. Difficulty may arise when attempting to supply an electric signal to control an actuator of the pump due to the difficulty of connecting a wire harness within the enclosed environment. Accordingly, a need exists for an electric auxiliary oil pump.

SUMMARY

An externally mounted electric fluid pump for pumping fluid within a power transmission device is disclosed. The pump includes a housing adapted to be mounted to an external surface of the power transmission device. The pump is positioned within the housing and includes an input member. An electric motor is positioned within the housing and drives the input member. A controller is positioned within the housing to control the electric motor and vary the output of the pump.

The present disclosure also provides an externally mounted electric pump for pumping fluid within a power transmission device. The pump includes a first housing member adapted to be mounted to an external surface of the power transmission device with a first recess having a substantially planar first pump surface surrounded by a first wall. A second housing member is fixed to the first housing member with a second recess having a substantially planar second pump surface surrounded by a second wall as well as being spaced apart from and extending substantially parallel to the first pump surface. A gerotor pump includes an inner rotor and an outer rotor, each rotor having opposite faces positioned adjacent the first and second pump surfaces, the outer rotor being aligned on an axis of rotation by the first and second walls. A rotor shaft engages each of the first and second housing members and defines an inner rotor axis of rotation offset from the outer rotor axis of rotation. An electric motor stator is positioned with a pocket formed in one of the first and second housing members. A plurality of permanent magnets is fixed for rotation with the outer rotor, the magnets being positioned proximate the stator.

DETAILED DESCRIPTION

With reference toFIG. 1, an integrated electric auxiliary oil pump10is fixed to a housing12of an exemplary transmission14by a plurality of externally accessible fasteners16. Pump10includes a housing18enclosing each of the pump components as well as a controller20(FIG. 11). A controller connector22protrudes from housing18to allow electric power to be supplied to pump10.

FIGS. 2-11depict pump10in greater detail. In particular, housing18includes a mounting face24for engagement with an external surface of transmission housing12. An inlet26and an outlet28are formed in housing18and are positioned to communicate with apertures extending through transmission housing12. O-rings30seal the interface between transmission14and pump10.

An inlet bore32is in fluid communication with inlet26. An inlet plug34is provided to seal the passageway. A check valve36is positioned within a check valve bore38extending through housing18. A check valve plug40seals check valve bore38from the atmosphere. A relief valve44is positioned within a relief valve bore46. A relief valve plug48is fixed to housing18to close relief valve bore46off from the atmosphere.

Housing18also includes a cavity52defined by a substantially cylindrical wall54. A boss56protrudes inwardly from an end wall58that intersects cylindrical wall54. A cylindrical surface60of cylindrical wall54acts as a guide for a stator62. An inner shoulder64of boss56provides an axial stop for an outer gear66of a gerotor pump assembly68. A cylindrical bore69intersects shoulder64and serves to define an axis of rotation of outer gear66.

A shaft74is pressed into pump housing18. As an option, shaft74may be secured to housing18by a retaining ring or a fastener. Shaft74includes an external surface that defines an axis of rotation of an inner gear76that is parallel to and offset from the axis of rotation of outer gear66. The eccentric arrangement between external lobes of inner gear76and lobes formed on outer gear66create the fixed displacement pumping action of gerotor pump assembly68. Inner gear76is rotatably supported on shaft74. A permanent magnet86is fixed to outer gear66. Outer gear66and stator62are supported such that a small predetermined gap exists between permanent magnet86and an inner diameter of stator62to allow relative rotation thereto. An oil passage88extends through shaft74to allow fluid to lubricate the interface of inner gear76and shaft74. Oil passage88interconnects a high pressure zone and a low pressure zone to assure flow occurs through this area.

A support plate90is clamped against a shoulder92formed on shaft74. A support plate washer94and a nut96secure support plate90against shoulder92. A predetermined gap exists between a face98of support plate90and side faces of inner gear76and outer gear66. To provide additional support to support plate90, a pump cover102includes a convoluted portion104placed in biased engagement with an upper surface106of support plate90. An outer perimeter of cover102is fixed to housing18by a crimping operation. Other retention means may also be used to couple cover102to housing18.

A high pressure port108communicates with outlet28. Inlet26and inlet bore32supply both sides of gerotor pump assembly68with low pressure fluid. More particularly, a first inlet port110extends through support plate90to provide pressurized fluid to one side of gerotor pump assembly68. A second inlet port111extends through housing18to provide low pressure fluid to the opposite side of gerotor pump assembly68. A plurality of circumferentially spaced apart slots112are formed in support plate90to allow fluid flow between a first cavity114and a second cavity116defined by cover102.

Check valve36includes a check valve ball126biased into engagement with housing18by a check valve spring128. Check valve36functions to permit oil flow in only one direction and prevent the flow from reversing. Check valve plug40reacts the load provided by check valve spring128.

Relief valve44includes a relief valve ball132biased into engagement with a seat134formed in housing18by a relief valve spring136. Relief valve plug48reacts the load from relief valve spring136. Relief valve44provides over-pressure protection to the components of pump10. When an over-pressure condition occurs, relief valve ball132will overcome the load provided by relief valve spring136to allow highly pressurized fluid to pass through a gallery140that is in communication with the inlet to gerotor pump assembly68.

Controller20includes a board150having electrical input provided from controller connector22. The output from board150is coupled to stator62such that electrical current is provided through the windings of stator62to create an electromagnetic field. In the Figure, board150is positioned within a cavity152that does not contain pumped fluid. Board150is dry. Cavity152may be sealed through the use of a plug (not shown) allowing stator wires to pass therethrough. Board150may alternatively be encapsulated to keep it dry. Controller20may include an integrated circuit or integrated circuits operable to determine the current being provided to stator62. Also, controller20may be operable to determine the torque applied to outer gear66. In an alternate arrangement, board150may be exposed to the pumped fluid.

In operation, pump10receives current from an external source through controller connector22. Energy is provided to controller20where a determination is made whether to provide current to stator62. The magnitude of current to be provided to stator62is also determined. As the magnitude of current provided to stator62varies, the strength of an electromagnetic field surrounding stator62is also varied. The electromagnetic field interacts with permanent magnet86causing outer gear66to rotate. Because outer gear66is in meshed engagement with inner gear76, the inner gear76is also forced to rotate. Rotation of inner gear76and outer gear66causes pumping action from inlet26to outlet28.

FIGS. 12-18depict another pump identified at reference numeral200. Pump200is also configured as an integrated electric auxiliary oil pump adapted to be coupled to a power transmission device such as transmission14. Pump200may be externally mounted to transmission housing12. Pump200includes a housing202with an inlet port204and an outlet port206. Housing202defines a cavity208having a side wall210. A recess214is defined by a substantially cylindrical wall216. Threaded apertures218are circumferentially spaced apart from one another.

As best shown inFIGS. 16-18, pump200includes a stator222positioned within cavity208. Side wall210is sized to closely fit an outer surface224of stator222to restrict stator222from radial movement. A land226is formed on housing202to partially define cavity208and provide a seat for a surface228of stator222to restrict axial movement of the stator relative to housing202.

A magnet ring232includes a substantially cylindrical portion234and a radially inwardly protruding portion236. Magnet ring232includes a metallic backing ring portion and a plurality of magnets formed as one component. An outer substantially cylindrical surface238is spaced apart from an inner substantially cylindrical surface240of stator222. An outer rotor242is fixed to magnet ring232. A seat246and a substantially cylindrical wall248are sized to clear the outer dimensions of outer rotor242but be closely positioned to the outer rotor to maintain a desired radial and axial position of outer rotor242.

A cover250is fixed to housing202by a clamp ring252and fasteners254. Cover250also defines a substantially planar surface256and a substantially cylindrical surface258that maintain the position of outer rotor242. The alignment of cylindrical surfaces258and248is achieved by closely sizing an outer cylindrical surface262of cover250with cylindrical wall216. An inner rotor266drivingly mates with outer rotor in similar fashion to that previously described with reference to inner gear76and outer gear66. Inner rotor266is fixed to a center shaft268. Inner rotor266and center shaft268are configured to rotate as a singular unit relative to housing202and cover250. A bore270formed in housing202and a bore272formed in cover250receive ends of center shaft268and define its axis of rotation. Face256and seat246limit axial translation of inner rotor266.

FIG. 18depicts a dowel280positioned to assure accurate alignment and indexing of cover250relative to housing202. A seal282is positioned within a groove290formed in cover250and engages recess214.

FIGS. 19 and 20relate to another integrated electric auxiliary oil pump identified at reference numeral300. Pump300includes a monolithic housing302including a mounting portion304, a pump and motor portion306and a controller portion308. A pump and motor controller310is positioned within controller portion308. A controller cover312sealingly engages controller portion308of housing302. Controller310is positioned within a sealed environment free from contact with the fluid to be pumped.

FIGS. 21 and 22depict a portion of an alternate pump identified at reference numeral350. Pump350is substantially similar to pump200with the exception of a ring-shaped controller352being positioned adjacent stator222. Controller352includes a board354positioned in engagement with stator222. A number of electronic components including an integrated circuit356, a capacitor358and a microprocessor360are fixed to board354. Controller352is operable to control operation of pump350. Board354and the components coupled thereto may be in communication with the fluid in which pump350is submersed. Based on the properties of the fluid to be pumped, controller352will function properly regardless of exposure to the fluid. A central aperture362extends through board354. Central aperture362is sized and positioned to allow inner rotor266and outer rotor242to pass therethrough.