Background of the Invention
This invention relates generally to a pump and motor assembly and more specifically to the manner in which a motor armature is accurately aligned with a cam or stator ring of a pump.
A known pump and motor assembly is disclosed in U.S. patent application Ser. No. 748,061 filed Dec. 6, 1976 by Drutchas et al. and entitled "Pump and Motor Assembly". The pump and motor assembly disclosed in this application includes an electric motor having an armature shaft. One end of the armature shaft is rotatably supported by a bearing which is mounted in a dividing wall between pump and motor sections of a common housing. A cheek plate of the pump unit is supported in coaxial relationship with the motor armature by mounting the cheek plate on the same bearing as is utilized to support the motor armature shaft. An anchor pin engages the dividing wall to hold the cheek plate against the rotation. Dowel pins which are separate from the anchor pin, extend outwardly from the opposite side of the inner cheek plate to support the cam ring of the pump unit. Problems may be encountered with this construction due to a build-up of tolerances between the various reference surfaces for positioning the motor armature shaft and pump cam ring.
Summary of the Present Invention
The present invention provides a new and improved pump and motor assembly in which the problem of build-up of tolerances between locating surfaces for various components of a pump and motor are eliminated. This is accomplished by using a single reference surface to locate both the motor armature and the pump cam ring.
The pump and motor assembly includes a housing having an inner surface which defines a chamber in which the pump and motor are located. A plurality of locating pins extend outwardly from opposite sides of a cheek plate of the pump. The locating pins engage the inner surface of the housing to accurately locate a bearing surface on the cheek plate relative to the central axis of the housing. This bearing surface is used to rotatably support an end of the motor armature shaft to which a rotor of the pump is connected.
The opposite end portions of the locating pins engage the cam ring or stator of the pump to accurately position the cam ring relative to the motor armature shaft and the rotor of the pump. Since the inner surface of the housing is utilized to accurately position the motor armature shaft, the pump rotor and the pump cam ring relative to each other, the pump and motor assembly is readily assembled without inaccuracies resulting from a build-up of tolerances between various locating surfaces.
Accordingly, it is an object of this invention to provide a new and improved pump and motor assembly in which a build-up of tolerances between various components of the pump and motor assembly is prevented by using the same reference surface to accurately locate components of the pump relative to components of the motor.
Another object of this invention is to provide a new and improved pump and motor assembly in which locating elements extend between a cheek plate of the pump and an inner surface of a housing to locate an armature shaft bearing surface on the cheek plate of the pump in a coaxial relationship with a stator ring of the pump.
Another object of this invention is to provide a new and improved pump and motor assembly wherein a plurality of pins extend outwardly from opposite sides of a support plate and engage a housing to locate a motor armature bearing surface on the support plate relative to the housing and to locate a pump cam ring relative to the motor armature.
Another object of this invention is to provide a new and improved method of assembling a pump and motor in a common housing and wherein the method includes engaging the housing with a plurality of locating elements to accurately position a motor armature bearing surface and a pump cam ring relative to each other.
Brief Description of the Drawings
The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:
FIG. 1 is a sectional view of a pump and motor assembly constructed in accordance with the present invention;
FIG. 2 is a sectional view, taken on a reduced scale along the line 2--2 of FIG. 1, and illustrating the relationship between the inner surface of a motor housing, a plurality of locating pins, and a motor armature shaft;
FIG. 3 is a sectional view, taken along the line 3--3 and on the same scale as FIG. 2, illustrating the relationship between the housing, locating pins, and a pump cam ring and rotor; and
FIG. 4 is an enlarged fragmentary sectional view of a portion of FIG. 1 and illustrating how one of the locating pins engages an inner surface of the housing.
Description of Specific Preferred Embodiments of the Invention
A pump and motor assembly 10 is illustrated in FIG. 1 and includes a housing 12 having a casing or main wall 14 which is stamped as one piece from sheet metal. A circular end wall 16 is fixedly connected to the casing 14. The casing 14 has a circular dividing wall 18 which separates a cylindrical motor chamber 20 from a cylindrical pump chamber 22. An electrical motor 24 is disposed in the motor chamber 20 in a coaxial relationship with a pump 26 disposed in the pump chamber 22.
The motor 24 is energized from a suitable source of electrical energy to drive the pump 26. The motor 24 includes a cylindrical stator 32 which is fixedly connected with a cylindrical inner surface 34 of the casing 14. The stator 32 circumscribes a motor armature 38 having a shaft 40 which is supported at one end by a bearing 42. The opposite end of the motor armature shaft 40 extends through the plastic dividing wall 18 and rotates about the central axis of the motor stator 32 and housing 12 to drive the pump 26 when the motor 24 is energized.
During operation of the pump 26, fluid is conducted from an annular inlet passage 46 formed in the cast metal end wall 16 of the housing 12 to the cylindrical pump chamber 22 through passages 48 and 50. At the same time, fluid under pressure is discharged from the pump to a cylindrical outlet cavity 54 which is connected with an outlet passage 56. Although the pump and motor assembly 12 can be utilized in many different environments, it is contemplated that it will advantageously be utilized in association with a vehicle fuel supply system in the manner disclosed in the aforementioned Drutchas et al application Ser. No. 748,061 filed Dec. 6, 1976.
The pump 26 is of the well known slipper type and includes a rotor 62 (see FIGS. 1 and 3) which is mounted on an end portion 64 of the armature shaft 40. When the rotor 62 is rotated by the motor armature shaft 40, slippers 66 (FIG. 3) mounted in notches on the rotor 62 are moved through a pair of pumping chambers 68 and 70 formed between the rotor 62 and a cam ring 72. As the slippers move around the inner surface of the cam ring 72, the size of pockets or working chambers formed between the slippers 66 are varied to pump fluid in a well known manner.
Fluid from the chamber 22 is directed into the pumping chambers 68 and 70 through inlet passages 74 (see FIG. 1) formed in an inner cheek plate or end portion 76. The circular inner cheek plate 76 is disposed between the cam ring 72 and the dividing wall 18 which separates the pump chamber 22 from the motor chamber 20. The inlet passages 74 in the inner cheek plate 76 cooperate with surfaces 80 formed in the cam ring 72 and surfaces 82 formed in an outer cheek plate 84 to direct fluid into the pumping chambers 68 and 70 in the manner disclosed in the aforementioned Drutchas et al. application Ser. No. 748,061. Suitable outlet passages (not shown) are formed in the circular outer cheek plate 84 to conduct fluid from the pumping chambers 68 and 70 to the outlet chamber 54.
In addition to the inlet passages 74, the inner cheek plate 76 has a central opening 88 in which a cylindrical bearing sleeve 90 is disposed. The bearing sleeve 90 has a cylindrical bearing surface 92. The bearing surface 92 engages the cylindrical outer surface of the armature shaft 40 to rotatably support the end portion 64 of the armature shaft.
In accordance with a feature of the present invention, the motor 24 and pump 26 are located in a coaxial relationship with each other and with the housing 12 by a plurality of locating pins or dowels 96, 98 and 100 (see FIGS. 1, 2 and 3). The parallel locating pins 96, 98 and 100 extend rightwardly (as viewed in FIG. 1) from the pump cheek plate 76 into engagement with the cylindrical inner surface 34 of the casing 14 to locate the armature shaft bearing surface 92 in a coaxial relationship with the cylindrical motor section 20 of the casing 14 (see FIG. 2). The pins 96, 98 and 100 support the cheek plate 76 (FIG. 1) in this position to maintain the central axis about which the motor armature 40 rotates coincident with the central axis of the housing 12 and motor stator 24.
In addition, the locating pins 96, 98 and 100 are used to support the cam ring 72 in a coaxial relationship with the motor armature shaft 40 and housing 12. Thus, the parallel locating pins 96, 98 and 100 extend leftwardly (as viewed in FIG. 1) from the cheek plate 76 into engagement with a plurality of generally U-shaped recesses 104, 106 and 108 (see FIG. 3) formed in the outside of the cam ring 72. The dowel pins also extend leftwardly (as viewed in FIG. 1) from the cheek plate 76 for a distance sufficient to enable the outer cheek plate or pressure plate 84 of the pump 26 to be mounted on the dowel pins in a coaxial relationship with the inner cheek plate 76 and cam ring 72.
Inaccuracies in aligning the components of the pump 26 and motor 24 are avoided by using a single reference surface. Thus, the locating pins 96, 98 and 100 use a single reference surface, that is the inside surface 34 of the casing 14, to position and support the pump 26 in a coaxial relationship with the housing 12. This same reference surface is also used to locate and support the bearing surface 92.
The locating pins 96, 98 and 100 are of the same construction. Thus, the locating pin 98 (see FIG. 4) has a cylindrical outer surface 112 which has an interference fit with a cylindrical passage 114 extending through the cheek plate 76 to hold the dowel pin 98 against axial movement relative to the cheek plate. The cylindrical outer surface of the dowel pin 98 also has an interference fit with the cylindrical inner surface 34 of the casing 14. The other two locating pins 96 and 100 also have interference fits with the cheek plate 76 and the casing 14. Due to the three point contact of the parallel locating pins 96, 98 and 100 with the cylindrical inner surface 34 of the casing at a location which is axially offset from the cheek plate 76, the cylindrical bearing surface 92 is accurately aligned with the central axis of the casing 14 and the motor 24.
The locating pins 96, 98 and 100 support the pump 26 in the pump chamber 22 with the outer side surface of the pump spaced from the cylindrical portion 118 of the inner surface 34 of the casing. This spacing enables fluid conducted from the inlet 96 to flow around the pump 26 and into the fluid inlet passages 74 in the manner described in the aforementioned Drutchas et al application Ser. No. 748,061.
To promote accurate positioning of the cam ring 72 relative to the central axis of the bearing surface 92, the locating pins 96, 98 and 100 have an interference fit with the recesses 104, 106 and 108 on the outside of the cam ring. The locating pins 96, 98 and 100 also have a tight fit with the outside of the outer cheek plate 84. However, the fit with the outer cheek plate 84 is not as tight as the interference fit with the cam ring 72. This arrangement of the components of the pump 26 enables the locating pins 96, 98 and 100 to align the pump with the motor armature shaft 40 and to hold the components of the pump against rotation when the motor 24 is energized to rotate the pump rotor 62.
The inner cheek plate 76 of the pump 26 is located axially relative to the armature shaft 40 by engagement of an inner major side surface 124 (see FIG. 4) of the cheek plate 76 with a connector or shoulder section 126 of the casing 14. The annular shoulder section 126 has an inner surface 130 which extends radially between the relatively small diameter motor section 20 and the relatively large diameter pump section 22 of the casing 14. Therefore, the cheek plate 76 of the pump is located both radially and axially by the inner surface 34 of the motor casing 14. This is because the locating pins 96, 98 and 100 engage the inner surface 34 to position the cheek plate 76 radially and the circular major side surface 124 of the cheek plate engages the radially extending area 130 of the inner surface 34 to position the cheek plate axially.
The cam ring 72 has a circular inner major side surface 134 which is disposed in abutting engagement with a circular outer major side surface 136 of the cheek plate 76 to locate the cam ring axially in the pump chamber 22. The end plate or pressure plate 84 has a circular inner major side surface 140 which is pressed against the outer major side surface 142 of the cam ring 72 by a spring 144. During operation of the pump and motor assembly 10, fluid pressure in the outlet chamber 54 assists the spring 44 in pressing the entire stack up of pump parts axially toward the right (as viewed in FIG. 1) to maintain the cheek plates 76 and 84 in tight abutting engagement with the cam ring 72 and to press the inner cheek plate 76 firmly against the shoulder section 126 of the casing 14.
When the motor 24 and pump 26 are to be assembled in the housing 12, the motor stator 32 is first fixedly connected with the inner surface 34 of the casing 14 by means of a suitable adhesive. The motor armature 38 is then located in the stator 32 with the inner end of the armature shaft 40 supported by the bearing 42. The dividing wall 18 is then positioned in the casing 14 to separate the motor chamber 20 from the pump chamber 22. The dividing wall 18 holds the motor armature brushes and has several openings through which fluid may flow back and forth between the motor chamber 20 and pump chamber 22. It should be noted that the dividing wall 18 is ineffective to support the motor armature 38. Therefore, the shaft end 64 of the motor armature is, at this time, free to move sideways relative to the casing 14. It is contemplated that a removable retainer could be used to temporarily support the motor armature shaft if desired during handling of the casing prior to installation of the pump 26.
To install the pump 26 in the casing 14, the locating pins 96, 98 and 100 are pressed into the cheek plate while the cheek plate is outside of the casing. The locating pins 96, 98, and 100 have the same length and extend inwardly for the same distance from the major inner side surface 124 of the cheek plate 76. The pump rotor 62, slippers 66 and their associated biasing springs are positioned in the cam ring 72 to form what is referred to as a cam pack. The cam pack is then positioned in abutting engagement with the outer major side surface 136 of the cheek plate 76 by pressing the cam ring axially toward the cheek plate to force the locating pins 96, 98, and 100 into the recesses 104, 106 and 108 on the outside of the cam ring. Finally, the outer cheek plate 84 is pressed into the engagement with the locating pins 96, 98 and 100 to retain the cam pack in position against the inner cheek plate 76 to thereby form the pump assembly 26.
The pump assembly 26 is then installed as a unit in the casing 14. This is done by axially aligning the inner cheek plate 76 with the outer end portion 64 of the motor armature shaft 40. The pump assembly is then moved axially into the pump cavity 22. Before the leading ends of the pins 96, 98, and 100 engage the cylindrical inner surface 34 of the casing 14, the outer end portion 64 of the armature shaft 40 moves into engagement with the cylindrical bearing surface 92.
Continued inward movement of the pump assembly 26 moves the leading ends of the locating pins 96, 98 and 100 into engagement with the inner side surface 34 of the casing at a location just inwardly of the shoulder 126. As the pump assembly 26 is pressed axially toward the shoulder 126, the locating pins 96, 98, and 100 slide along the inner surface 34 of the casing 14. The interference fit between the cylindrical outer surfaces of the locating pins 96, 98 and 100 and the cylindrical inner side surface 34 of the casing causes the locating pins to accurately locate the bearing surface 92 and the outer end portion 64 of the armature shaft 40 in a coaxial relationship with the motor stator 32.
The inward movement of the pump assembly 26 is stopped when the circular major side surface 124 of the cheek plate 76 abuts the annular shoulder 126. It should be noted that at this time the cheek plate 76 acts as a support plate for the motor armature shaft 64 and is effective to hold the motor armature shaft against sidewise movement. In addition, the locating pins and cheek plate 76 are effective to support the cam ring 72 and outer cheek plate 84. Although it is preferred to use the inner cheek plate 76 of the pump assembly 26 to support the motor armature shaft 40, it is contemplated that in certain embodiments of the invention it may be desirable to provide a support plate which is separate from the pump cheek plate.
Once the pump assembly 26 has been positioned in the pump chamber 22 in the manner previously described, the end wall 16 is bolted to the casing 14 with the spring 144 and a suitable seal 152 located in the outlet chamber 54. The pressure of the spring 144 against the seal 152 and the outer cheek plate 44 holds the components of the pump 26 in position in the chamber 22. However, if desired, suitable spring clips could engage the outer ends of the locating pins 96, 98 and 100 to hold the components of the pump relative to each other. Although it is contemplated that many different types of slipper and rotor constructions could be utilized in the pump assembly 26, it is contemplated that the pump will be utilized to handle fluids with a relatively low viscosity and therefore the slippers 66 have been provided with a continuous cam engaging surface proportioned in accordance with the teachings of U.S. Pat. No. 3,797,977.
Although the previously described sequence of assembly operations is preferred, it is contemplated that other assembly sequences could be utilized. For example, it is contemplated that the inner cheek plate 76 could be positioned in the pump chamber 22 and the cam pack, that is the cam ring 72, rotor 62, and slippers 66 and associated biasing springs, could be installed on the cheek plate 76 after the cheek plate has been positioned in the housing. In addition, it is contemplated that the outer cheek plate 84 could be inserted after the cam pack and inner cheek plate have been installed in the pump chamber 22.
In view of the foregoing description, it is apparent that the present invention provides a new and improved pump and motor assembly 10 in which the problem of build-up of tolerances between locating surfaces for various components of a pump 26 and motor 24 are eliminated. This is accomplished by using a single reference surface 34 to locate both the motor armature 38 and the pump cam ring 72.
The pump and motor assembly 10 includes a housing 12 having an inner surface 34 which defines a chamber in which the pump and motor are located. A plurality of locating pins 96, 98 and 100 extend outwardly from opposite sides of a cheek plate 76 of the pump 26. The locating pins 96, 98 and 100 engage the inner surface 34 of the housing 12 to accurately locate a bearing surface 92 on the cheek plate 76 relative to the central axis of the housing. The bearing surface 92 is used to rotatably support an end 64 of the motor armature shaft 40 to which a rotor 62 of the pump is connected.
The outer end portions of the locating pins engage the cam ring or stator 72 of the pump 26 to accurately position the cam ring 72 relative to the motor armature shaft 40 and the rotor 62 of the pump. Since the inner surface 34 of the housing is utilized to accurately position the motor armature shaft 40, the pump motor 62 and the pump cam ring 72 relative to each other, the pump and motor assembly 10 is readily assembled without inaccuracies resulting from a build-up of tolerances between various locating surfaces.