A MOUNTING STRUCTURE FOR AN ELECTRIC MOTOR

Abstract: A mounting structure is provided for an electric motor (24) and associated gear means (86,94,96,98). The electric motor (24) has a mounting flange (68) and includes a drive shaft (84) operatively associated with the gear means (86,94,96,98). The structure includes a housing portion (35) for receiving the mounting flange (68) and for enclosing at least a portion of the motor 24), a pair of guide members (88,90) for co-operation within a pair of apertures (92) of the mounting flange (68) to restrain the mounting flange (68) moving in a rotational direction relative to the housing portion (35), and a plurality of resilient fingers (52,56) for receiving and securing the mounting flange (68) in the housing portion (35). The housing portion is provided with hubs (100) integral therewith for journaling the gear means (86,94,96,98), and retaining means (112) for retaining the gear means (86,94,96,98) on the hubs (100).

Description: The present invention relates to a mounting structure for an electric motor having a mounting flange and more particularly, but not exclusively, to a mounting structure for mounting an electric motor to the frame of a printing apparatus. It is known for a printing apparatus to require one or more small electric motors to drive certain parts of the printer. A small motor is used to drive the print head carriage in reciprocating manner in the printer that includes a stationary platen and a movable print head. A second motor is used to drive the paper such as a receipt, a slip or a journal at the end of the printing operation and which paper drive is usually performed at the ends of the lines of printing. The demands of certain printing operations place a high duty cycle on the drive motor and associated drive mechanisms and it is essential that the motor and mechanisms be secured and contained in an appropriate manner because the motor and mechanisms are relied upon for long lasting operation which may involve either continuous or intermittent duty. The use of screws, bolts, nuts and the like is well-known for securing the motor mounting flange to a side frame of the printer. Other fastening members have included self-tapping screws, for example, in plastic frames or serrated washers engaging the surface of metal frames. One of the disadvantages of employing a number of such parts for securing the motor mounting flange to the side frame is that installation time is generally high. Also if one of the parts is incorrectly installed or of poor quality it may work itself loose or fail and thereby permit undamped relative movement between the motor and side frame causing deleterious effects on the motor and its operational efficiency. It is an object of the present invention to provide a mounting structure for an electric motor having a mounting flange, the structure having mounting means enabling the electric motor to be easily installed and when so installed to be securely positioned and resiliently restrained therein. Thus according to the invention, there is provided a mounting structure for an electric motor and associated gear means, said electric motor having a mounting flange and including a drive shaft operatively associated with said gear means, characterized by a housing portion for receiving said mounting flange and for enclosing at least a portion of said motor, said housing portion including locating means for cooperating with said mounting flange to restrain said mounting flange moving in a rotational direction relative to said housing portion and a plurality of inwardly extending resilient fingers whereby upon insertion of said motor into said housing portion said mounting flange engages and deflects outwardly said resilient fingers which return to their original position after passage of said mounting flange and which engage a surface of said mounting flange to retain said motor in said housing portion, said mounting flange being in engagement with a surface of a locating wall of said housing portion, said locating wall having journaling means integral therewith for journaling said gear means, and retaining means for retaining said gear means on said journaling means. An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a printer showing the motor mounting arrangement; Fig. 2 is a left side elevational view of a printer frame member incorporating the structure of the present invention; Fig. 3 is a top view taken on the line 3-3 of Fig. 2; Fig. 4 is a front view taken on the line 4-4 of Fig. 2; Fig. 5 is a right side elevational view of the printer frame member taken in the direction opposite from Fig. 2; Fig. 6 is an enlarged view, partly in section, of the gear mounting arrangement; Fig. 7 is an enlarged view, taken from the side of Fig. 2, of the snap element for retaining the gear; Fig. 8 is a top view of the snap element of Fig. 7; and Fig. 9 is a sectional view of the snap element, taken on the line 9-9 of Fig. 7. Fig. 1 is a perspective view of a printer 10 incorporating the structure of the present invention. The printer 10 includes a journal station 12, a receipt station 14, and a slip station 16. The journal station 12 is positioned on the right hand side of the printer 10 and the receipt station 14 and the slip station 16 occupy the left side of the printer. A more detailed description of the arrangement of the receipt station 14 and the slip station 16 is found in US-A-4 780 007. A print head 18 of the dot matrix type is mounted on a carriage 20 that is moved in well-known manner back and forth across the printer 10 in printing operations. Fig. 2 is a side elevational view of a frame member 22 which provides the means for mounting a circular-shaped electric motor 24 in the printer 10, as best illustrated in Fig. 5. The frame member 22 is of unitary construction and preferably is made of plastic in a molding operation. A preferred material for the member 22 is polycarbonate with 15% PTFE (polytetrafluoroethylene) and 15% carbon fiber to provide for electrostatic discharge grounding. Another material that may be used is polycarbonate with 15% PTFE and 20% glass fiber. The frame member 22 is a portion of the printer 10 and is located in a left hand cavity 26 (Fig. 1) of the printer and provides support and bearing means for other parts or elements of the printer. The frame member 22 (Fig. 2) includes a plate portion 28 having a bearing opening 30 for a shaft (not shown) that is used to support and drive a paper drive roller for receipt paper. A second bearing opening 32 is provided for a shaft (also not shown) that is used to support a camming roller operated for use with form or slip type media. A third bearing opening 34 is provided in the plate portion 28 to support a pivot shaft (not shown) also operated for use with form or slip type media. The orientation and mechanism of the structure associated with the bearing openings 30, 32 and 34 are fully described in US-A-4 780 007. The plate portion 28 provides supporting structure for record media (form or slip) thickness compensating mechanism which is described in the above-noted application. The frame member 22 (Fig. 2) is formed to provide an enclosure-type configuration, as 35, of generally square shape that includes walls 36, 38, 40 and 42 (Fig. 5). The walls 36, 38, 40 and 42 extend in an outward direction (toward the viewer in Fig. 2 and away from the viewer in Fig. 5) from the plate portion 28. The top wall 36 and the right hand wall 42 (Fig. 5) are essentially the same form, and the left hand wall 38 and the bottom wall 40 are similar in form except that the wall 38 is formed integral with the plate portion 28 of the frame member 22. A sidewall 44 connects and is integral with the four walls 36, 38, 40 and 42. The lower right hand corner of wall 42 and the upper left hand corner of the sidewall 44 (Fig. 5) are provided with cutout portions, as 46 in wall 42 and as 48 in sidewall 44 (Fig. 2). The wall 42 includes a finger 52 extending outwardly at an angle from a narrow portion 54 of the wall 42, and the sidewall 44 includes a finger 56 extending outwardly from the sidewall 44 (Fig. 3). The finger 56 is secured at its base end to the sidewall 44 and is secured to the wall 38 by means of a gusset 58 (Fig. 5) integral with the wall 38 and a portion 60 of the finger 56. The finger 56 is formed in turn-over manner and includes a first slanting portion 62 and a second slanting portion 64 (Fig. 3). The finger 52 has a tip 66 (Fig. 5) at the end thereof for engaging with a square mounting flange 68 of the motor and the finger 56 has a tip 70 at the end of the second slanting portion 64 for engaging with the mounting flange 68. A plurality of spaced apertures 76, 78 and 80 (Fig. 2) are provided in the plate portion 28, the aperture 76 being placed in an upper portion 72 of the plate portion 28. The apertures 76 and 80 are provided to secure certain parts of the forms compensating mechanism and the aperture 78 is a clearance for a record media (form or slip) drive shaft (not shown). A circular recess 74 (Fig. 5) is provided in the upper portion 72 of the plate portion 28 to accommodate one end of the record media thickness compensating mechanism, mentioned above. An opening 82 (Fig. 2) is provided in the sidewall 44 of the enclosure 35 to allow insertion of a motor shaft 84 having a splined member in the form of a drive gear 86 thereon. The sidewall 44 also includes a pair of pilot studs 88 and 90 as an integral part thereof and projecting towards the viewer in Fig. 5. The mounting flange 68 (Fig. 5) of the motor 24 has apertures 92 (Fig. 2) at the corners thereof for receiving the pilot studs 88 and 90. While the mounting flange 68 has four apertures 92 (Fig. 5), only two pilot studs 88 and 90 are deemed necessary in a preferred arrangement. The motor 24 is inserted in an axial direction from the right in Fig. 4 and the motor mounting flange 68 bears against the fingers 52 and 56 (Figs. 3 and 5) and deflects the fingers outwardly from the center of the enclosure 35. The pilot studs 88 and 90 guide the mounting flange 68 by means of the apertures 92 receiving the studs. The tips 66 and 70 (Fig. 5) of the respective fingers 52 and 56 capture the edges of the motor mounting flange 68 and secure the motor 24 in place against the sidewall 44 by snap action of the fingers in a direction back to their normal unrestrained position. This structure and positioning of the parts eliminates any axial play between the motor 24 and the frame member 22 which may be caused by any clearance between the motor flange 68 and the snap fingers 52 and 56. The drive gear 86 (Fig. 2) is secured to the motor shaft 84 and engages with a first gear 94 positioned adjacent and upwardly from the drive gear 86. Gear 94 engages with a second gear 96 and with a third gear 98 which are positioned adjacent and relative to the first gear 94 to be simultaneously driven thereby. When the motor 24 is rotating in the clockwise direction (Fig. 2) the drive gear 86 is driven in the clockwise direction and the first gear 94 is driven in the counterclockwise direction. Both the second gear 96 and the third gear 98 are driven in the clockwise direction in an arrangement for driving receipt paper from the receipt station 14 and past the line of printing by driving the receipt paper shaft (not shown but journaled in bearing 30) in a counterclockwise direction. Fig. 6 is a sectional view of a portion of the sidewall 44 against which the mounting plate 68 of the motor 24 is secured by the snap fingers 52 and 56 (Fig. 3). The sidewall 44 includes a plurality of hubs or journals, as 100, integral with the sidewall and extending outwardly in spaced, parallel arrangement. The hubs or journals 100 provide bearing surfaces for the first gear 94, the second gear 96 and the third gear 98 (Fig. 2), such first gear 94 being illustrated in Fig. 6. The sidewall 44 includes a plurality of apertures, as 102 (Figs. 5 and 6), at precise positions in the sidewall and extending through each of the hubs or journals 100. The aperture 102 has a reduced diameter portion 104 near the outer end of the hub or journal 100 to provide a circular ledge 106 for receiving fingers 108 and 110 of a fastening element 112 (Fig. 8) for securing the gear 94 (Fig. 6). The fastening element 112, illustrated in an enlarged face view in Fig. 7, a top view in Fig. 8, and a sectional view in Fig. 9, is made of polycarbonate material by a molding process. The fastening element 112 has a circular face portion 114 of washer-like form which is connected to a central portion 116 by web portions 118 and 120 (Fig. 7). Openings 122 and 124 are provided in the face portion 114 of the element 112. The fingers 108 and 110 are an extension of the central portion 116 and are circular shaped except for the bifurcated structure. The finger 108 has a slanted surface 126 on a tip portion 128 and a lip 130, and the finger 110 has a like slanted surface 132 on a tip portion 134 and a like lip 136. The lips 130 and 136 fit over the circular ledge 106 of the hub 100 (Fig. 6) when the fastening element 112 is pressed into the reduced diameter portion 104 of the aperture 102 in the hub or journal 100. It is thus seen that herein shown and described is a motor and gear mounting bracket for use in a printer. The bracket has a plurality of snap fingers that are engageable by the motor mounting flange and are biased upon insertion of the motor to spring outwardly and then to spring inwardly to capture the mounting flange. The drive gears are retained on journals or hubs by means of spring fingers which are sprung inwardly and then sprung outwardly to capture the drive gears.

Claims: A mounting structure for an electric motor (24) and associated gear means (86,94,96,98), said electric motor (24) having a mounting flange (68) and including a drive shaft (84) operatively associated with said gear means (86,94,96,98), characterized by a housing portion (35) for receiving said mounting flange (68) and for enclosing at least a portion of said motor (24), said housing portion (35) including locating means (88,90) for cooperating with said mounting flange (68) to restrain said mounting flange (68) moving in a rotational direction relative to said housing portion (35), and a plurality of inwardly extending resilient fingers (52,56) whereby upon insertion of said motor (24) into said housing portion (35) said mounting flange (68) engages and deflects outwardly said resilient fingers (52,56) which return to their original position after passage of said mounting flange (68) and which engage a surface of said mounting flange (68) to retain said motor (24) in said housing portion (35), said mounting flange (68) being in engagement with a surface of a locating wall (44) of said housing portion (35), said locating wall (44) having journaling means (100) integral therewith for journaling said gear means (86,94,96,98), and retaining means (112) for retaining said gear means (86,94,96,98) on said journaling means (100). A mounting structure according to claim 1, characterized in that said resilient fingers (52,56) are integrally formed with a wall or walls (38,42,44) of said housing portion (35). A mounting structure according to claim 1 or claim 2, characterized in that said locating means (88,90) includes a pair of guide members (88,90) for co-operation within a pair of apertures (92) of said mounting flange (68). A mounting structure according to any one of claims 1 to 3, characterized in that said journaling means (100) includes a plurality of hubs (100) spaced in parallel relationship with said drive shaft (84) and said gear means (86,94,96,98) includes a plurality of gears (86,94,96,98), each of said hubs (100) having an aperture (102) therethrough, and means (106) engageable by said retaining means (112) for retaining each of said gears (86,94,96,98) on a respective hub (100). A mounting structure according to claim 4, characterized in that said engageable means (106) includes a reduced diameter portion defining a ledge (106) engageable by said retaining means (112). A mounting structure according to claim 4, characterized in that said retaining means (112) includes a pair of resilient finger elements (108,110) sprung inwardly during insertion thereof into said aperture (102), engaging with said retaining means (112) and returning to their original position after engaging with said engageable means (106). A mounting structure as claimed in any one of claims 1 to 6, characterized in that said housing portion (35) is molded of polycarbonate material with polytetrafluroethylene and carbon fiber material. A mounting structure according to claim 6, characterized in that said resilient finger elements (108,110) include slanted tip portions (128,134) sprung inwardly during insertion into said hubs (100) and having lip portions (130,136) engageable with said hubs (100) for retaining the gears (86,94,96,98) on said hubs (100). A mounting structure according to claim 1, characterized in that said journaling means (100) includes a plurality of hubs (100) integrally formed on a surface of said locating wall (44) opposite to said surface against which said mounting flange (68) is in engagement. A mounting structure according to claim 9, characterized in that said retaining means (112) includes resilient snap-fit means (108,110) for retaining said gear means (86,94,96,98) on said hubs (100).

Inventors: WEEKS, DAVID E.
Applicants: NCR INTERNATIONAL INC.
Application year: 1989
Main classification: B41J29
IPC codes: F16M1, B41J29