GB2158154A - Rotary fuel-pump for an I.C. engine - Google Patents

Abstract

The pump includes a case (12) having an inlet chamber (38), a motor chamber (28), and a chamber (34) for gerotor-type pumping means (142, 144). An outlet housing (18) receives the pressured fuel through an electric motor (20) in the motor chamber. A dog coupling (112, 114) connects the inner member (142) of the pumping means to the armature shaft (64) of the motor. An axial flow-channel for the fuel may be provided between the motor field magnets (240,242). <IMAGE>

Description

SPECIFICATION Wet motor gerotor fuel pump The present invention relates to fuel pumps and, more particularly, to fuel pumps wherein the armature of the driving motor is immersed in the fluid being pumped.

One of the elements heretofore limiting the life of a wet motor fuel pump has been wear life of the slot and key coupling between the driving member of the motor and the driven member of the pump. Such wear is especially critical where the pump is a gerotor pump because the wear affects the clearance and also the wearing of the gear teeth effecting the pumping. Moreover, such slot and key couplings generate noise that increases with wear.

Another problem with wet motor pumps is that the rotating armature of the motor affects the flow of fuel thereby. The rotating armature creates turbulence in the fuel flow that reduces the flow rate and increases the armature current required for such reduced flow rate. Moreover, such turbulence undesirably increases the fuel temperature.

A further problem with fuel pumps of the gerotor type is that the tight tolerances on the gear members of the gerotor pump impose similarly tight tolerances on other members of the pump such as the armature shaft and the bearings supporting it. To the extent that such tolerances are tighter than might otherwise be necessary, the overall cost of the pump is increased.

A further problem with gerotor pumps is that they are comparatively expensive to manufacture and assemble because of the greater number of higher precision parts. Moreover, other parts such as the motor magnets must be cemented into place in careful alignment with and clearance from the armature, interference between the armature and magnets being a known failure mode and interference between the pump end of the armature windings and the port plate of the pump being another.

The invention in one aspect is set forth in Claim 1 and in another aspect is set forth in Claim 8.

In a preferred embodiment, a unitary tubular pump case encloses and aligns a one piece inlet and pump housing, a gerotor pump outlet plate, a motor flux ring, and a shoulder of an outlet housing, the pump case also having a tubular inlet adapted to be coupled with a source of fuel. The inlet and pump housing houses the inner and outer pump gears of a gerotor pump and cooperates with the outlet housing to rotatably support the end portions of an armature shaft of a wet motor armature so as to allow slight end-forend self-alignment of the armature shaft relative to the inner pump gear which is still precisely aligned with the gerotor cavity and outer pump gear.The armature windings are looped about the fingers of a fiber hub secured to the armature shaft which has a pair of diametrically opposed drive dogs projecting axially into a coupling cavity provided in the inner gerotor pump gear. A pair of driven dogs on the inner pump gear project radially into the coupling cavity and are there drivingly mated with the driving dogs of the fiber hub.

A thrust washer mounted on the fiber hub against a thrust shoulder thereon also has a pair of driven dogs extending radially inwards to mate with and be driven by the drive dogs of the fiber hub. The thrust washer bears against a suitable thrust surface in a pump outlet plate functioning to enclose the inner and outer pump gears in a gerotor cavity provided in the inlet and pump housing. The pressurized fluid pumped through the pump outlet plate is channeled in a channel established between one set of circumferentiallyjuxtaposed axial surfaces of a pair of cresentshaped motor magnets.Such axial surfaces are separated circumferentially by a keeper inserted therebetween having a central bridge portion abutting radially against the motor flux ring and bounded by a pair of leg portions opening radially inwards towards the armature to abut against the one set of axial surfaces of the crescent shaped motor magnets. A compression spring is inserted between the other set of circumferentially-juxtaposed axial surfaces of the motor magnets to urge the first set circumferentially against the legs of the keeper, such compression spring thereby establishing a second axial flow channel past the armature.

It is thus possible to provide a new and improved wet motor fuel pump.

It is also possible to provide a fuel pump of the foregoing type wherein the driving member of the motor is coupled to the driven member of the pump by a face dog or tang coupling.

It is also possible to provide a fuel pump of the foregoing type wherein the wear life of the pump is enhanced and the noise generated thereby is reduced compared to a conventional slot and key coupling.

It is also possible to use a face dog cou pling to drive a driven gerotor gear while at the same time allowing a slight end-for-end self-alignment of the armature shaft relative to the bore of the driven gear.

It is also possible to support the pump end of the armature shaft in a bushing resiliently supported by the inlet housing of the pump, such resilient support permitting a slight selfalignment of the armature shaft with respect to the gerotor elements.

It is also possible to enhance the thrust bearing between the motor and the pump outlet plate.

It is also possible to provide a wet motor fuel pump wherein flow rates are increased at reduced armature currents at the same time such flow is made smoother and cooler than for conventional wet fuel pumps of comparable size and capacity.

It is also possible to provide a new and improved structure for flowing fuel past the rotating armature, such structure channelling the flow through an axial channel established between adjacent motor magnets and opening inwardly towards the rotating armature.

It is also possible to provide the foregoing channel with a magnet spacer or keeper opening radially inwards toward the armature and functioning to circumferentially separate the juxtaposed axial surfaces of the motor magnets.

It is also possible to provide a wet motor fuel pump having a pump case that aligns the major elements of the pump including the inlet and pump housing, the pump outlet plate, the motor flux ring, and also the outlet housing.

It is also provided to provide a pump case of the foregoing type that also serves as the inlet coupling for the pump while also being sealed to the outlet housing by a lip of the pump case flanged inwardly over a shoulder of the outlet housing.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is an end view of one embodiment of a wet motor gerotor fuel pump having certain features provided in accordance with the present invention; Figure 2 is an axial cross-sectional view of the gerotor fuel pump of Fig. 1 taken along line 2-2 thereof; Figure 3 is a transverse radial cross-sectional view of the gerotor fuel pump of Fig. 2 taken along line 3-3 thereof; Figure 4 is a transverse radial cross-sectional view of the gerotor fuel pump of Fig. 2 taken along line 4-4 thereof; Figure 5 is an enlarged and exaggerated view of portions of an armature shaft and inner gerotor pump gear; Figure 6 is a cross-sectional view of the outlet housing with an outlet check valve and vent valve of the gerotor fuel pump of Fig. 1 taken along line 6-6 thereof;; Figure 6A is a cross-sectional view of an imperfect valve seat and ball valve of the vent valve of Fig. 6 taken along line 6A-6A thereof; Figure 7 is a view of the gerotor fuel pump of Fig. 2 taken along line 7-7 thereof; Figure 8 is a fragmentary plan view of a portion of Fig. 2 showing the orientation of the outlet housing by the use of an indexing tab positioned between the two motor magnets; Figure 9 is an exploded view in perspective of the gerotor fuel pump shown in Figs. 1 through 8; Figure 9A is a perspective view of the coupling arrangement of the armature shaft and the inner gerotor pump gear of Figs. 1 through 9; Figure 9B is a perspective view of an alternative less preferable embodiment of the keeper of Figs. 7 and 9;; Figure 10 is a partial sectional view of a portion of an alternative outlet housing, showing a vent-relief valve and a bushing for rotably supporting an end portion of the armature shaft; Figure 10A is a perspective view of portions of an alternative version of the support bushing and outlet housing of Fig. 10 showing the slot and key arrangement thereof for limiting circumferential rotation of the bushing; Figure 11 is a perspective view of a pop-off valve of the vent-relief valve shown in Fig.

10; Figure 12 is a top view of the alternate outlet housing of Fig. 10; Figure 13 is a bottom view of the internal configuration of the alternate outlet housing of Fig. 12; Figure 14 is a cross-sectional view through just the alternate outlet housing of Figs.10, 12, and 13 taken along line 14-14 of Fig.

12; Figure 15 is a view taken through just the outlet housing of Figs. 10. 12, 13, and 14 taken along line 1 5-1 5 of Fig.12; and Figure 16 is an exploded view in perspective of certain features of the alternate outlet housing assembly, certain parts thereof being broken away.

With reference now primarily to Figs. 2 and 9, there is shown a wet motor gerotor pump assembly or pump 10 for receiving a fluid such as fuel from a source such as a fuel tank (not shown) and delivering pressurized fluid to a utilization device such as an internal combustion engine (not shown). The wet motor gerotor pump assembly or pump 10 includes a tubular stepped case 1 2 generally enclosing an inlet and pump housing 14, a gerotor pump assembly 16, a motor flux ring 17, a pump outlet plate 180, and being sealed against an outlet housing 1 8 with an electric motor assembly 20 supported between the inlet and pump housing 14 and the outlet housing 18.

The tubular stepped case 1 2 terminates at one end in a sealing lip 22 flanged inwardly to seal against an outwardly extending annular shoulder 24 of the outlet housing 1 8.

Towards its other end, the tubular stepped case 1 2 includes an outer bore 26 generally defining a motor chamber 28, a pump bore 30 optionally stepped inwardly from the outer bore 26 at a shoulder 32 and generally defining a pump chamber 34, and an inlet bore 36 stepped inwardly from both the outer and pump bores 26 and 30 and generally defining an inlet chamber 38. The inlet chamber 38 is adapted to be communicated in a known manner with a fuel source (not shown) such as by a known fluid coupling, conduit and filter (not shown).

Made of a one-piece diecast zinc structure, the inlet and pump housing 14 has a cylindrical outer periphery 40 fitted into the pump bore in the pump chamber 34 of the tubular stepped case 1 2. At an inlet end thereof, the inlet and pump housing 14 terminates in a tubular hub 42 protruding into the inlet bore 36 and inlet chamber 38 of the tubular stepped case 1 2 and also has a stepped bore 44 of a structure and function to be described in greater detail hereinafter. The cylindrical exterior 45 of the tubular hub 42 is separated by an annular space 46 from an encircling annular spring washer 48 having an inner diameter portion 50 seated against an annular hub seat 52 protruding axially inwardly from the interior of the tubular stepped case 1 2.

The annular spring washer 48 also has an outer diameter portion 54 captured axially and radially in an annular counterbore 56 formed on the inlet side 58 of the inlet and pump housing 14 just inboard of the cylindrical outer periphery 40 thereof.

The electric motor assembly 20 includes an armature shaft 60 having an armature shaft inlet end 62 and an armature shaft outlet end 64, each shaft end being rotatably supported by a respective tubular bushing or bearing 66 and 68 slip-fitted thereon and resiliently supported by O-rings 70 and 72 respectively engaging a bore 74 in the inlet and pump housing 14 and a bore 76 in the outlet housing 18. The tubular bushing 66 is lubricated and cooled by fuel in the inlet chamber 38, and the tubular bushing 68 is lubricated by fluid fed through axial slots 75 spaced about the periphery of the bore 74.The armature shaft 60 is positioned generally along a central flow axis 78 through the wet motor gerotor pump assembly 10 and is positioned therealong by the thrust washer 1 82 being actively against the thrust washer seat 184 which is part of the port plate 1 80 by means of the magnetic attraction acting between the magnets 240 and 242 and the armature stack. The inlet bearing 66 is positioned by means of a shoulder 80 extending outwardly from the tubular bushing 66 and an annular shoulder 82 extending inwardly from the tubular hub 42 to thereby capture the O-ring 70 therebetween.

Adapted to rotate in the motor chamber 28, the electric motor assembly 20 includes an armature 84 made of q plurality of armature windings 86 wound through a plurality of slotted armature laminations (not shown) press fitted on a knurled portion (not shown) of the armature shaft 60. Each armature winding 86 has respective first and second ends terminated in a known manner at a commutator 88 adapted to electrically and slidingly engage a pair of diametrically opposed commutator brushes 90 and 92 electrically coupled to respective cup-shaped terminals 91 and 93. The brushes 90 and 92 are urged against the commutator 88 along a brush displacement axis 94 by a respective first and second brush spring 96 and 98.

Press fitted on the knurled portion of the armature shaft 60 axially outboard the opposite ends of the armature laminations are a first and a second end fiber 100 and 102, each having eight fingers 104 extending radially outwards from a fibrous central tubular hub 106 spaced equiangularly thereabout, each finger 104 having at its tip an axially extending tab 108 extending axially inwards towards the armature laminations to provide a stand off therefrom. The outward axial side of each finger 104 has a smooth curved outer surface therealong so as to non-abrasively engage and support the end loops of the armature windings 86.The fibrous central tubular hub 106 of the end fiber 102 has an annular thrust shoulder 110 extending radially outwards therefrom and terminates axially in a pair of drive tangs or dogs 11 2 and 114, best seen in Fig. 9, in the form of diametricallyopposed arcuate sections extending axially towards and into the inlet and pump housing 14.

As may be better understood with reference to Figs. 2, 3, and 9, the inlet and pump housing 1 4 has a counterbore 11 6 opening towards the armature 84 and defining a gerotor cavity 11 8 and also has a central bore 1 20 therethrough. The counterbore 116, the gerotor cavity 118, and the central bore 1 20 are concentric about an offset axis 122, best seen in Figs. 3 and 9, having a predetermined radial offset 1 24 from the central flow axis 78 along a first radial direction generally perpendicular to the brush displacement axis 94.As may be better understood with reference to Figs. 2, 4, and 9, an oblong depression 1 26 and an oblong aperture 1 28 are provided in a bottom surface 1 30 of the counterbore 11 6 and are disposed generally concentrically about the centrsl bore 1 20. As best seen in Fig. 4, the inlet side 58 of the inlet and pump housing 14 has an oblong inlet depression 1 32 extending axially therein.The oblong inlet depression 1 32 on the inlet side 58 communicates with a first oblong aperture 1 28 in the bottom surface 1 30 of the counterbore 11 6 and a second oblong inlet depression 1 36 on the the inlet side 58 of the inlet and pump housing 1 4 also communicates with the entire oblong aperture 1 28 in the bottom surface 1 30. The first and second apertures 1 32 and 1 36 cooperate to provide unpressurized fluid to the gerotor cavity 11 8 for both priming the gerotor pump assembly 1 6 and providing fluid to be pressurized thereby.

Located in the gerotor cavity 118 of the gerotor pump assembly 1 6 are an inner pump gear 142 and an outer pump gear 144, shown only in Fig. 3. The inner and outer pump gears 142 and 144 have respective series of inner and outer pump teeth 1 54 and 1 56 and pump teeth spaces 1 58 and 1 60 intervening therebetween.The inner pump teeth 1 54 of the inner pump gear 142 being formed to pumpingly seal and engage the outer pump teeth 1 56 and teeth spaces of the outer pump gear 144, while the outer pump teeth 1 56 of the outer pump gear 144 are formed to pumpingly seal and engage the inner pump teeth 1 54 and the teeth spaces 1 58 of the inner pump gear 142.The outer pump gear 144 has a cylindrical external periphery 1 62 that is slip-fittingly received by and positioned in the counterbore 116 of the gerotor cavity 11 8. The inner pump gear 142 has a central bore 1 64 therethrough which, as may be better understood with reference to Figs. 2 and 5, has a tapered opening 1 66 facing the bottom surface 1 30 of the counterbore 1 16 of the inlet and pump housing 14.

The internal diameter of the inner gear bore 164 is slightly greater (e.g., 0.001 inches) than the external diameter of the armature shaft 60 passing therethrough and the axial length of the inner gear bore 1 64 is selected to be comparatively short (e.g., 0.005 inches) with respect to the internal diameter thereof so as to allow the armature shaft 60 to pivot slightly end-to-end relative to the inner gear bore 1 64 and thereby allow the O-ring 70 to self-align the armature shaft inlet end 62 in the bore 74 of the tubular hub 42. Such selfaligning allows the armature shaft 60 to effect small angles with respect to the central flow axis 78, such angles increasing with increasing manufacturing and assembling tolerances.

While thus allowed to self-align relative to the inner pump gear 142, the armature shaft 60, as better seen in Figs. 3 and 9A nevertheless drives the inner pump gear 142. The inner pump gear 142 has a pair of driven tangs or dogs 1 72 and 1 74 extending radially inwards therefrom into the drive coupling cavity 1 70.Forming a drive coupling 1 77, as best seen in Figs. 3 and 9A, each of the drive tangs 11 2 and 114 have an included angle of approximately one hundred and eighteen degrees (118"), and each of the driven tangs 1 72 and 1 74 have an included angle of about fifty-eight degrees (58"). The four tangs 112, 114, 172 and 1 74 thereby having a total circumferential clearance of approximately eight degrees (8 ). Such clearance allows sufficient circumferential play to permit easy assembly of the drive coupling but also slight axial misalignment thereof to allow the end-for-end self-alignment of the armature shaft 60 relative to the inner pump gear 142.

Completing the gerotor pump assembly 1 6 are an annular pump outlet plate 1 80 and a thrust washer 1 82 made of Teflon loaded Ultem. The pump outlet plate 180 has an annular thrust surface 1 84 counterbored into the outlet side 186 thereof and a bore 188 therethrough of a diameter sufficient to allow the drive tangs 11 2 and 114 of the fibrous central tubular hub 106 to freely pass therethrough with a suitable clearance (e.g., 0.005 inches).The pump outlet plate 1 80 also has a cylindrical outer periphery 1 90 and an annular radial groove 1 92 extending inboard therefrom, the outer peripheral surface 1 90 being received in the outer bore 26 of the tubular stepped case 1 2 and being seated against the face of the annular shoulder 32 therein, providing both radial and axial positioning relative to the flux ring 1 7. The thrust washer 1 82 is pressed against the annular thrust surface 1 84 of the pump outlet plate 1 80 by the annular thrust shoulder 110 of the fibrous central tubular hub 1 06. The thrust washer 1 82 has a pair of diametrically-opposed arcuate tangs or dogs 1 93a and 1 93b extending radially inward to engage and be driven by the dogs 11 2 and 114 of the fibrous central tubular hub 106.

On an axial side facing the inner and outer pump gears 142 and 144, the pump outlet plate 1 80 also has an oblong depression 1 96 and aperture 1 98 generally matching the shape and position of the oblong depression 1 26 and the oblong aperture 1 28 in the bottom surface 1 30 of the counterbore 11 6 of the gerotor cavity 118 of the inlet end pump housing 14.To afford proper pump priming and other desirable pumping characteristics, the oblong aperture 1 28 and the oblong depression 1 96 are communicated through, respectively, bores 1 20 and 1 88 by appropriate radial slots 200 and 202, as best seen in Figs. 2 and 9. Moreover, to provide a suitable outlet port for fluid pumped to a fluid pressure in the gerotor cavity 118, the pump outlet plate 1 80 has an outlet aperture 1 98 formed therethrough and positioned and shaped to correspond with the oblong depression 126. To properly position the pump outlet plate 1 80 circumferentially with respect to the inlet and pump housing 14, a pair of locator pins 204 and 206 are affixed thereto to extend axially from an annular radial surface 208 to engage suitable holes 205 and 207 through an annular radial surface 209 of the pump outlet plate.

Pressure fluid from the oblong aperture 1 98 of the pump outlet plate 1 80 is guided therefrom and protected from the windage effects of the armature 84 by a tunnel and magnet keeper device 210, best seen in Figs. 7 and 9. The tunnel and magnet keeper device 210 consists of a first flow channel or passage 211 shielded from the armature windage extending substantially the entire axial length of the motor chamber 28 between the pump outlet plate 1 80 and the annular shoulder 24 of the outlet housing 1 8. Shaped generally in the form of an inverted staple, the tunnel and magnet keeper device 210 has a central bridge portion 21 2 bounded by a pair of leg portions 214 and 216.The central bridge portion 21 2 has a slightly convex shape, as seen from a point external to the pump, to match the circular contour of the periphery of the armature 84, and the pair of leg portions 214 and 216 extend radially outwards from the central bridge portion 21 2 to seat on the inner peripheral surface 21 8 of a cylindrical magnetic motor flux ring 1 7. The flux ring 1 7 also extends substantially the entire axial length between the pump outlet plate 1 80 and the outwardly extending annular shoulder 24 of the outlet housing 1 8.

To allow substantially unimpeded flow of pressure fluid from the outlet aperture 1 97 into the tunnel and magnet keeper device 210 while also imparting a desired circumferential position to this device, the inlet end 222 thereof is provided with two axially extending protrusions 224 and 226 spaced radially apart to provide a fluid entrance 228 therebetween. The axial protrusion 224 terminates in a butt end 230 abutting directly against the annular radial surface 209 of the pump outlet plate 1 80. The axial protrusion 226 terminates in a stepped tab 232 having a but end 232a abutting against the radial surface 209 and a pin portion 232b extending into the outlet side of the hole 207 provided to properly orient the pump outlet plate 1 80 with the inlet and pump housing 14 as aforementioned.

The leg portions 214 and 21 6 of the tunnel and magnet keeper device 210 cooperate with a pair of tabs 234 and 236 extending circumferentially outwards from the respective axial protrusions 224 and 226 to properly position the pair of cresent shaped motor magnets 240 and 242 both circumferentially and axially with respect to the armature 84.

As may be better understood with reference to Figs. 7, 8 and 9, each cresent shaped motor magnet 240 and 242 is bounded along its axial length by a first and a second set of juxtaposed axial surfaces 240a, 240b, 242a and 242b, and each motor magnet 240 and 242 is bounded at its inlet and outlet ends by respective end surfaces 240c, 242c, 240d and 242d.

In assembly, the tunnel and magnet keeper device 210 is first inserted so that the axial pin portion 232b thereof is positioned in the locator hole 207 of the pump outlet plate 180. Thereafter, the crescent-shaped motor magnets 240 and 242 are inserted so that the axial surfaces 240a and 242a respectively abut the leg portions 214 and 216 and the end surfaces 240c and 242c abut the tabs 234 and 236. To properly space the motor magnets 240 and 242 from the outlet port plate 180 and provide a second axial channel 211a therebetween, a V-shaped compression spring 246 is then inserted between the second set of juxtaposed axial surfaces 240b and 242b to urge the axial surfaces 240a and 242a circumferentially into abutting contact with the leg portions 214 and 216. of the magnet keeper 210.

Finally, the outlet housing 1 8 is inserted into the tubular stepped case 1 2. The circumferential orientation of the outlet housing 1 8 being determined relative to the tunnel and magnet keeper device 210, as best seen in Fig. 8, by an arcuate tab 248 extending between the axial surfaces 240b and 242b of the cresent shaped motor magnets 240 and 242. A pump outlet port 250, through the outlet housing 18, is thereby aligned along the same axial plane intersecting the center of the tunnel and magnet keeper device 210 and the center of the outlet aperture 1 98 through the pump outlet plate 1 80.

The foregoing proper circumferential orientation of the outlet housing 1 8 relative to the tunnel and magnet keeper device 210 permits a flow of pressure fluid smoothly therethrough directly from the outlet aperture 198, through the first flow passage 211, to the pump outlet port 250 of the outlet housing 1 8.

It has been found through experimental test results, under standard conditions, that the foregoing apparatus substantially improves pump performance. Compared with wet pumps of similar size and capacity, the foregoing wet motor pump assembly provided the desired fluid pressure at substantially increased flow rates with substantially decreased armature currents. For example, in one typical application to a conventional passenger car internal combustion engine, flow rates were uniformly increased by at least three gallons per hour while the corresponding armature currents were decreased at least twelve percent (12%).

Some portion of this improvement is attributed to merely providing the axial flow channel, such as the magnet keeper 21 0a of the type shown in Fig. 9B. Such a keeper has a central bridge portion 21 2a abutting radially outwards against the flux ring 1 7 and bounded by a pair of leg portions 214a and 21 6a opening radially inwards towards the armature 84. However, such a keeper would allow the armature windage to induce radially oriented hydraulic curls in the flow channels 211b. But such turbulence would reduce the effective cross-sectional area of the axial flow channel 211 b to a small portion of the actual cross-sectioned area thereof. To avoid such curls and turbulence and substantially increase the effective area, the tunnel and magnet keeper device 210 of the preferred embodiment is provided so that the central bridge portion 21 2 thereof shields the flow therethrough from the armature windage. Should further improvements be desired to avoid hydraulic curls induced with an orientation in the channel 211 by the flow restriction imposed by the circumferential width thereof, the channel 211 could be further subdivided into subchannels of a plurality of tubes or slots. Such subchannels would provide a laminar flow substantially increasing the effective cross-sectional area of the flow to the actual cross-sectional area of the channel.

As best seen in Figs. 1 and 6, the outlet housing 18 made of a molded plastic such as Ultem, includes the pump outlet port 250 with a tubular outlet fitting 252 adapted to be coupled to an internal combustion engine.

The tubular outlet fitting 252 has an internal outlet passage 251 with a slotted seal 253 fitted into an outlet bore 254 to enclose a ball valve 255 of a one-way check valve 256 therein. The outlet housing 18 provides an annular seat 257 cooperating with the ball valve 255 to provide the one-way check valve 256 preventing backflow from the engine into the fuel pump. To allow normal flow from the fuel pump 10 to the engine, the outlet fitting 252 terminates in four tapered prongs 258 forming slots 259 therebetween, the tapered prongs 258 normally restraining the outward movement of the ball valve 255 and the slots 259 allowing the fuel to flow out therebetween. The angle formed by the tapered prongs 258 is such as to cradle the ball valve 255 so as to prevent oscillation of the ball at certain flow rates.

A further feature of the wet motor pump assembly is a vapor vent valve 260 provided in the outlet housing 18, as best seen in Figs.

6 and 6A. The vapor vent valve 260 is located diametrically opposite the outlet valve 250, and includes a ball 262 enclosed in a valve bore 264 by a tubular vent fitting 266 having a vent passage 268 therethrough and having an annular hub 270 seated against an annular seating surface 272 of the outlet housing 18. A helical spring 274 biases the ball 262 away from a shoulder 276 encircling an annular internal hub 278 of the tubular vent fitting 266 and towards an imperfect seal in the form of a square seat 280, best seen in Fig. 6A, at the end of a vent bore 282 formed in the outlet housing 18. When in contact with the square seat 280, the ball 262 touches the square seat 280 at only four points 284a, 284b, 284c, and 284d, such arrangement providing four suitable bypass passages 286a, 286b, 286c and 286d.With this arrangement a vapour pressure developed by the gerotor pump assembly 16, especially during self-priming thereof, is unloaded through bypass passages 286a, 286b, 286c, and 286d until liquid reaches the output side of the pumping elements and the vent bore 282. Thereafter, the fluid pressure on the ball 262 will overcome the bias thereon by the helical spring 274 to seat the ball 262 on the annular internal hub 278 formed at the inboard end of the tubular vent fitting 266, thereby closing the vent passage 268 and allowing normal pumping operation and outlet through the outlet port 250.

The square seat 280 in the foregoing vapor vent valve 260 may be replaced by other suitable non-circular, or imperfect, valve seats including, for example, partially-circular valve seats as might be effected by a circular valve seat having axially extending slots therethrough.

A further application of an imperfect valve seat is in combination with a vent-relief valve 290 shown molded into the alternate outlet housing 1 9 in Figs. 1 0 and 11. As may be better understood with reference thereto, a ball 292 is enclosed in a bore 294 provided in the outlet housing 19, the bore 294 defining therein a valve chamber 295. One end of the bore 294 is in constant communication with a vent-relief passage 296 provided through the end of the outlet housing 19, and the other end of the bore 294 is suitably secured, such as by ultrasonic welds, to a valve seat member 298 having a central passage 300 therethrough in constant communication with the motor chamber 28.The central passage 300 opens into an oblong valve seat 301 in the form of an oblong counterbore having a width equal to the diameter of the central passage 300 and a length twice thereof. When in contact with the seat member 298, the ball 292 can contact the oblong valve seat 301 either at two diametrically opposite points if centrally located thereon, or in a semi-circle line contact if shifted to either extreme side thereof. Either way, there is a bypass passage constantly open between the ball 292 and the oblong valve seat 301.

Also located in the valve chamber 295 formed by the bore 294 and the valve seat member 298 is a tubular pop-off or relief valve 302, a first helical spring 304, a second helical spring 306, and an O-ring 308. One end of the helical spring 304 is biased against an annular shoulder 310 formed in the ventrelief passage 296, and the other end of the helical spring 304 is biased against an annular top surface 312 formed at the top of the pop-off valve 302 and encircling a central vent passage 314 therethrough. The helical spring 304 biases the tubular pop-off valve 302 to normally seat and seal against the 0ring 308, the O-ring 308 being normally seated on an annular seat surface 316 provided on the valve seat member 298 about the oblong valve seat 301 thereof.When the pop-off valve 302 is thus normally urged against the O-ring 308 to seal against the annular seat surface 316, a normally-open bypass passage is established from the central passage 300 of the valve seat member 298, through the central vent passage 314 of the pop-off valve 302, and the vent-relief passage 296 of the outlet housing 1 9. This vent bypass passage being closed as will be described when the pump assembly 10 produces a fluid pressure in excess of a predetermined maximum venting pressure in the form of a liquid at the ball 292.

The tubular pop-off valve 302 also has an externally slotted tubular portion 31 8 having a tube bore 320, at one end clearing the outer diameter of the ball 292 and having an annular hub seat 322 depending internally from the other end. One end of the second helical spring 306 is seated about the annular hub seat 322, and the other end engages a peripheral surface of the ball 292 to normally urge the ball 292 to seat on the oblong valve seat 301. However, when the fluid pressure experienced by the pump 10 exceeds the maximum venting pressure, such excess pressure overcomes the bias of the second helical spring 306 on the ball 292 and moves the ball 292 towards the annular hub seat 322, seating on the same when the pump pressure exceeds the predetermined maximum venting pressure.At pump pressures between the maximum venting pressure and a predetermined relief pressure, the ball 292 closes the fluid passage between the central seat passage 300 and the vent-relief passage 296.

To provide a relief capability or condition when the pump experiences a fluid pressure in excess of the predetermined relief pressure, the axial periphery 324 of the pop-off valve 302 is provided with six ribs 326a, 326b, 326c, 326d, 326e, and 326f, extending radially outwards and spaced equiangularly thereabout on the tube portion 318, the ribs 326a through 326f also guiding and centrally positioning the pop-off valve 302 with respect to the bore 294. Each of the axial ribs 326a through 326f is contiguous with a respective spacer tab 328a through 328f upstanding axially from and about the annular roof surface 31 2 and the vent passage 314 therethrough.The tabs 328a through 328f are adapted to abut against and space the remainder of the pop-off valve 302 axially from an annular stop surface 330 counterbored in the outlet housing 1 9 about the vent-relief passage 296. The ribs 326a through 326f and the respective tabs 328a through 328f form passages or slots 332a through 332f therebetween spaced equiangularly about the periphery 324 of the pop-off valve 302. The slots 332a through 332f cooperate with the ventrelief passage 296 to continually communicate the entire space between the bore 294 and the periphery 324 of the pop-off valve 302 with the vent-relief passage 296.However, this space is not communicated with the central passage 300 until the pump experiences a fluid pressure in excess of the relief pressure, such excess pressure then overcoming the seating bias of the helical spring 304 against the O-ring 308 to thereby move the pop-off valve 302 away from the annular seat surface 316 and towards the annular stop surface 330. Such excess pump pressure thereby urges the pop-valve away from the 0ring 308 to unseat from the annular surface 316 thereby opening a passage through the slots 332a through 332f from the seat passage 300, between the bore 294, the periphery of 324 the pop-off valve 302, through the slots 332a through 332f, and out through the vent-relief passage 296.

Further alternate features of the pump 10, as shown in Figs. 10 and 10A are alternate tubular bushings 340 and 340a, the axial length of which has a convex form or raised portion in the shape of an outwardly extending bowl or crown 342 that contacts the bore 344 in the outlet housing 1 8 to allow a slight end-for-end self-alignment of the armature shaft 60. To restrain the tubular bushing from rotating in the bore 344, an anti-rotation device is provided in the form of a slot and key arrangement 348 wherein a slot 348a in the bushing 340 is circumferentially somewhat wider and radially somewhat deeper than a key 348b.

A further feature of the wet motor gerotor pump 10 is the utilization of otherwise existing structure in the alternate outlet housing 1 9 in combination with additional passages formed therein to cool and lubricate a portion of the tubular bushing 340 between the point of contact of the raised portion 346 with the bore 344 and the roof 360 of the outlet housing. As may be better understood with reference to the outlet housing 1 9 shown in Figs. 1 0 through 16, a bearing lubrication and cooling system 350 in the form of a flow network 354 is provided between a raised cap portion 352, a cylindrical peripheral surface 89 of the commutator 88, the bore 344, and a pair of support ridges 356 and 358 for supporting the brushes 90 and 92 respectively.

As best seen in Fig. 12, the raised cap portion 352 supports the outlet port 250 and the vent-relief valve 290 hose fitting, and includes the generally flat roof 360 supporting the outlet port 250 and the vent-relief valve 290 hose fitting and further includes a pair of side walls 362 and 364, and a pair of curved end walls 366 and 368.

The flow network 354, when viewed in the transverse radial plane of Fig.13, is shaped generally in the form of the Roman numeral X. More particularly, the flow network 354 includes four branches 370, 372, 374, and 376, each in the shape of a dog leg and each communicating with the axial length of the bore 344 as well as an annular recess 378 encircling a stop hub 380 projecting into the bore 344 from the roof 360. Each of the branches 370 through 376 extends axially along the bore 344 to the inner surface 361 of the roof 360. Each includes a side wall branch portion 370a, 372a, 374a, and 376a.

Each such side wall branch portion is generally parallel to one of the side walls 362 and 364, with the side wall branch portions 370a and 372a generally spanning the vent-relief valve 290 while the side wall branch portions 374a and 376a generally span the outlet port 250. Each of the branches 370, 372, 374, and 376 also include a radial branch portion 370b, 372b, 374b, and 376b, each terminating in a respective side wall branch portion with a respective radial slot 370c, 372c, 374c, and 376c formed circumferentially through a bore wall 382 providing the bore 344.

The brush support ridges 356 and 358 include an arcuate ridge crown or wall element 356a and 358a facing radially inward, the arcuate ridge crown 356a being bounded by a pair of radial ridge side walls 356b and 356c while the arcuate ridge crown wall 358a is bounded by a pair of radial ridge side walls 358b and 358c. Each set of the radial ridge side walls 356b, 356c, 358b, and 358c are spaced radially apart by an included angle of about ninety degrees (90 ) and, together with their respective arcuate ridge crown walls 356a and 358a, extend axially to an arcuate ridge wall counterbore 384 at a depth corresponding with the axial width of the commutator 88. The arcuate ridge crown walls 356a and 358a are of a diameter slightly greater than that of the commutators 88 to allow clearance therebetween for appropriate brush commutator interaction.The bore 344 commences at the depth of the arcuate ridge counterbore 384 and extends axially to the inner side 361 of the roof 360. With the bore 344 starting below the brush support ridges 356 and 358, there is an arcuate opening of approximately ninety degrees (90 ) between the radial ridge walls of the opposing brush support ridges 356 and 358. In other words, there is a circumferential gap of about ninety degrees (90 ) extending the axial length of the commutator 88 between the radial ridge side walls 356a and 358a, and a similar gap extends circumferentially between the radial ridge side walls 356b and 358b.

Assuming that the armature 84 is energized to rotate in a counterclockwise direction as viewed in Fig.13, the cylindrical periphery 89 of the commutator 88 viscously drags fluid therewith, such fluid being picked up by the rotation of the commutator at the slots 376c and 372c having, respectively, the radial ridge side walls 356c and 358b and being delivered or thrown off against the next radial ridge side walls 358c and 356c, respectively, of the slots 374c and 370c. The fluid picked up at the diametrically opposite radial ridge side walls 356c and 358b therefore experiences a higher velocity than the fluid impacting and collecting at the diametrically opposite ridge side walls 356b and 358c.This difference in velocities causes the fluid in the radial slot portions 370c and 374c to move slower and therefore be at a pressure higher than the fluid at the radial slot portions 372c and 376c. A similar pressure differential could be effected by other structures such as a vane or other form of flow resistance, the ridge walls in the present embodiment serving a dual function of supporting the brushes while also providing the necessary pressure differential.

In any event, the resulting pressure differential created by the drag forces of the commutator periphery 89 on the fluid at the indicated radial ridge side walls effects a pumping action of fluid in the radial branch portions 370b and 374b. Such pumping action is axially outwards towards the inner surface 361 of the roof, then radially inwards into the annular recess 378, then axially about the bushing 340, then radially outwards from the annular recess 378, and finally back through the opposing radial branch portions 372b and 376b. In other words, the commutator periphery 89, the support ridges 356 and 358, and the flow network 354 establish two parallel pumping chambers or circuits separated by the commutator 88 but joined at the annular recess 378.The pressure differentials created by the difference in velocities at the indicated radial ridge side walls provides two incoming and two outgoing flows of fluid thereat, both flows combining to cool and lubricate the tubular bushing 340 and the bore 344. With such cooling and lubrication, the life of the upper bushing 340 has been found to be significantly increased over the life of the same bearing without such lubrication and cooling. Moreover, an acceptable lubrication will also occur by providing just a single circuit communicating with the annular recess 378 communicating with the upper end portion of the bushing 340 above the point its crown 342 contacts the bore 344. Such lubrication would be less than that provided by the dual parallel circuit shown.Also, a slight flow of fluid might be provided by such a single circuit should the internal structure by happenstance provide a sufficient pressure differential between the inlet and the outlet to the annular recess 378, without the benefit of additional pressure building structures.

Although the best mode contemplated by the inventor for carrying out the present invention as of the filing date hereof has been shown as described herein, it will be apparent to those skilled in the art that suitable modifications, variations, and equivalents may be made without departing from the scope of the invention defined by the claims appended hereto.

Reference is made to the following copending applications of even data: Application No. 8427070 Application No. 8427071 Application No. 8427072 Application No. 8427073 the disclosures of which are hereby expressly incorporated herein by reference.

Claims (11)

1. A wet motor gerotor fuel pump for pumping fuel from a fuel source to an internal combustion engine, comprising: a pump case having one end, an opposite end and a flow axis therethrough, said pump case further comprising an inlet end bore at said one end adapted to communicate with said fuel source; an inlet chamber adjacent said inlet end bore; a motor chamber located in said opposite end of said pump case; a pump chamber interposed said motor chamber and said inlet chamber; first means for sealing said pump case, said first means for sealing located at said opposite end of said pump case;; inlet housing means mounted in said pump chamber, said inlet housing means comprising an annular hub protruding into said inlet chamber, said inlet housing means further comprising a gerotor cavity about a gerotor axis located parallel to and displaced a predetermined distance in an eccentric radial direction from said flow axis; outlet housing means having pump outlet means adapted to be communicated with said internal combustion engine and further comprising a second means for sealing coupled to said first means for sealing; electric motor means comprising armature means comprising an armature shaft with a first and a second end rotatably supported, respectively, at said inlet housing means and said outlet housing means, said armature means further comprising drive hub means having first tang means extending in a first radial direction relative to said armature shaft; and gerotor pump means located in said gerotor cavity, said gerotor pump means comprising an inner pump gear, an outer pump gear, and second tang means located on one of said inner and outer pump gears, said second tang means further extending in a second radial direction from said first radial direction and adapted to be drivingly coupled to said first tang means such that said fuel pump pumps fuel from said fuel source into said inlet chamber, through said gerotor means past said electric motor means into said outlet housing means substantially along said flow axis to said internal combustion engine.

2. The wet motor gerotor fuel pump of Claim 1, wherein said one of said inner and outer pump gears has a coupling cavity and said second tang means extend radially into said coupling cavity and wherein said drive hub means extends axially into said coupling cavity so that said first tang means engages said second tang means.

3. The wet motor gerotor fuel pump of Claim 1 or Claim 2, further comprising a first and a second bearing means for rotatably supporting said first and second ends of said armature shaft respectively in said inlet housing means and said outlet housing means, each of said first and second bearing means comprising a resilient mounting means to allow said armature shaft to have an axial alignment offset from said flow axis.

4. The wet motor gerotor fuel pump of Claim 3, wherein said first end of said armature shaft has an outer shaft diameter and protrudes through a bore in said inner pump gear, said bore of said inner pump gear having a bore diameter and a predetermined bore length to allow said armature shaft to pivot within a predetermined angular range with respect to said flow axis, whereby said resilient mounting means and said predetermined angular range cooperate to allow selfalignment of said armature shaft with respect to said flow axis.

5. The wet motor gerotor fuel pump of anyone of the preceding Claims, wherein said electric motor means further comprises: first and second magnet means, each of said first and second magnet means further comprising an inner and an outer axial surface extending in a direction along said flow axis about said armature means, a first and a second side surface extending in a direction along said flow axis, and a first and a second end surface; and magnet spacing means positioned between said first and second magnet means for spacing said first and second side surfaces of said first magnet means circumferentially with respect to said first and second side surfaces of said second magnet means.

6. The wet motor gerotor fuel pump of Claim 5, wherein said magnet spacing means comprises keeper means separating one of said first and second side surfaces of said first magnet means from one of said first and second side surfaces of said second magnet means to define an axial flow passage between said gerotor pump means and said outlet housing means and between said first and second magnet means substantially along said flow axis; whereby said axial flow passage allows fuel to be pumped about said armature means and to thereby improve pumping efficiency and performance.

7. The wet motor gerotor fuel pump of Claim 6, wherein said magnet spacing means further comprises spring means circumferentially biasing the other of said first and second side surfaces of said first magnet means from the other of said first and second side surfaces of said second magnet means to establish a second axial flow passage extending along said flow axis between said first and second magnet means.

8. A wet motor fuel pump for pumping fuel from a fuel source to an internal combustion engine comprising: a pump case having an inlet end, and outlet end, and a first, a second, and a third bore therebetween, said bores being coaxial with a flow axis therethrough and respectively defining a motor chamber, a pump chamber and an inlet chamber, and said inlet end adapted to be communicated with said fuel source; inlet housing means received in said pump chamber, said inlet housing means comprising a pump cavity in said pump chamber and a hub protruding into said inlet chamber; outlet housing means comprising outlet means adapted to be communicated with said internal combustion engine;; pump means comprising a port plate having an outlet port therethrough, said pump means being operative to pump fuel from said inlet chamber under fluid pressure through said outlet port and to said motor chamber; and electric motor means comprising armature means having an armature shaft with a first and a second end rotatably supported respectively at said inlet housing means and said outlet housing means, said electric motor means further comprising: first and second magnet means, each having an inner and an outer surface extending along said flow axis, a first and a second side surface extending along said flow axis, and a first and a second end surface; and magnet spacing means positioned between said first and second magnet means for spacing said first and second side surfaces of said first magnet means circumferentially with respect to said first and second side surfaces of said second magnet means.

9. The wet motor fuel pump of Claim 8 wherein said magnet spacing means comprises keeper means separating one of said first and second side surfaces of said first magnet means from one of said first and second side surfaces of said second magnet means to define an axial flow passage extending axially along said flow axis between said pump case and said armature means and between said first and second magnet means.

10. The wet motor fuel pump of Claim wherein said magnet spacing means comprises spring means circumferentially biasing the other of said first and second side surfaces of said first magnet means from the other of said first and second side surfaces of said second magnet means to establish a second axial flow passage extending axially along said flow axis between said first and second magnet means.

11. A wet motor gerotor fuel pump for pumping fuel from a fuel source to an internal combustion engine, substantially as hereinbefore described with reference to anyone of the embodiments shown in the accompanying drawings.