MOTOR ATTACHMENT ASSEMBLY FOR PLASTIC POST ISOLATION SYSTEM

[0001] This application claims the benefit of United States provisional patent application serial number 60/966,458 for a MOTOR ATTACHMENT FOR PLASTIC ISOLATION, filed on 8/28/07, which is hereby incorporated by reference in its entirety. This claim is made under 35 U.S.C. § 119(e); 37 CRR. § 1.78; and 65 Fed. Reg. 50093.

TECHNICAL FIELD OF INVENTION

[0002] The invention relates to a motor attachment assembly for attaching an electric motor to a motor mount; more specifically, for attaching an electric motor to a motor mount having a plastic post vibration isolation system.

BACKGROUND OF INVENTION

[0003] Electric motors, such as that of an electric blower motor mounted onto a heating, ventilating, and air-conditioning (HVAC) module of a vehicle, often produce vibrations in operation. The vibration can be transmitted from the motor through the HVAC module to other components of the HVAC system and eventually to the passenger compartment of a vehicle. To isolate the motor vibrations, the electric motor is typically fastened onto a motor mount assembly that has vibration isolating features, which is in turn mounted to the HVAC module. The motor mount assembly can be a separate component or an integral part of the HVAC module.

[0004] General attaching arrangements used to fasten an electric motor to an vibration isolating motor mount assembly and other known electric motor mount assemblies have

included the use of axial mounting studs protruding from the motor housing; band type mounts in the form of hoops or ring shaped wire straps that encircle the frame of the motor and attach to the motor mount by mounting arms; and bases that cradle the motors, where the bases have mount points to attach to the motor mount assembly. [0005] U.S. Patent Application 11/542,542, assigned to Delphi Technologies Inc. on October 3, 2006, discloses an electric blower motor mount assembly for a HVAC module having specially designed plastic isolation posts for isolating vibrations from the motor. The plastic isolation posts extend axially relative to the motor housing. One end of the post is attached to a support structure extending from the motor housing and the other end may be integrally molded with the HVAC module. The isolation posts are designed to provide a desired torsional stiffness to target the natural frequency of the motor and mount system such that isolation/attenuation occurs in the commutation order frequency range. In addition, the posts are designed to provide adequate radial stiffness such that the radial resonant frequency is not shifted in the 1 ^st order range (e.g. 16-67 Hz). [0006] The use of known attaching arrangements to attach an electric motor to a motor mount assembly requires an inventory of fasteners and increases the complexity of assembly. Several traditional methods of attachment may be used to attach the motor to the plastic isolation posts as taught by '542; however, there are shortcomings to such traditional methods. Use of screws would require a significant increase in the diameter of the plastic posts and would negatively impact their stiffness as well as adding labor costs and quality problems. Use of push nuts and Tinnerman nuts have similar problems of adding module assembly labor hours, as well as the potential for quality problems associated with dropped fasteners lodging in the motor or module. Snap fits require an

undercut in the posts which adds molding complexity. Also, snap fits generally have some "slop" which would allow excessive motor vibration. Attachment methods such as heat staking add capital cost and require extra radial clearance for the tooling to access the plastic nub for melting.

[0007] What is needed and desired is a high quality, cost effective, reliable, and compact motor attachment assembly to attach an electric motor to plastic isolation posts without significantly affecting the diameter of the plastic posts, without negatively affecting the designed isolation properties of the plastic posts, and without the potential of dropping fasteners into the final assembly.

SUMMARY OF THE INVENTION

[0008] The invention provides for a motor attachment assembly that includes an electric motor having spring clips adapted to securely lock onto the isolation posts of a plastic post vibration isolation system. The motor has an output shaft rotatable about an axis and a housing about the axis. The motor is positioned in an isolator cup that includes a plurality of isolation posts extending axially within the cup's compartment toward the output end of the motor. The motor further includes an end cap having a plurality of notches. The housing of the motor includes a rim that has a plurality of locator tabs extending in the direction of the output shaft. The locator tabs are inserted into the notches and have deformable fingers that are bent to lock the end cap to the housing. [0009] A plurality of spring clips is attached to the motor between the rim of the housing and the end cap. Each of the clips defines an axial channel that receives one of the plastic isolation posts. The clips include a latitudinal segment that defines an aperture to engage

the locator tabs. Each of the clips further includes an axial slot that is expandable in an open direction to increase the diameter of the axial channel to receive one of the isolation posts and biased in the closed direction to retain the isolation post by plastically deforming the post. Each clip has an inner surface with barbs protruding into the channel. The barbs are adapted to allow insertion of the isolation post into the channel in the direction of the output shaft and to resist movement of the isolation post in a direction opposite to the output shaft. The inner surface also possesses a plurality of retention grooves to receive the plastically deformed portions of the isolation post. [0010] The invention provides a high quality cost effective reliable motor attachment assembly to attach an electric motor to plastic isolation posts without significantly affecting the diameter of the plastic posts; therefore, would also not negatively impact the designed isolation properties of the plastic posts. The invention also eliminates the potential for dropping fasteners into the final assembly. The invention further reduces the complexity of assembly the motor onto the isolation post because the clips may be assembled with the motor assembly prior to attaching it to the isolation system. [0011] Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of an embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0012] This invention will be further described with reference to the accompanying drawings in which:

[0013] Fig. 1 is an exploded view of an electric motor detached from its housing with spring clips therebetween.

[0014] Fig. 2 is an exploded view of an electric motor with spring clips attached axially spaced from a plastic post vibration isolation system.

[0015] Fig. 3 is a perspective view of a plastic post attached to a portion of the isolator cup and a spring clip axially spaced from the plastic up.

[0016] Fig. 4 is a side view of the tip portion of a plastic post and a cross sectional view of a spring clip along line 4-4 prior to engagement to the plastic post.

[0017] Fig. 5 is a side view of the tip portion of a plastic post and a cross sectional view of a spring clip after engagement to the plastic post.

DETAILED DESCRIPTION OF INVENTION

[0018] In accordance with an embodiment of this invention, referring to Figs. 1-5, similar features are structured similarly, operate similarly, and/or have the same functions unless otherwise indicated by the drawings or this specification. Similar features have been numbered with a common reference numeral. The motor attachment assembly 2 includes an electric motor 10 having spring clips 11 adapted to securely lock onto plastic post 13 of plastic post vibration isolation system 19.

[0019] Shown in Fig. 1 is electric motor 10, typical of that of a blower motor for a vehicle HVAC system, having an output shaft 12 arrayed along axis 14 at the output end 15. For illustrative purposes, motor 10 is shown axially spaced apart from housing 16. Adapted to seal the internal workings of motor 10 within housing 16 at output end 15 of motor 10 is end cap 17. End cap 17 includes a port 18 from which output shaft 12

protrudes and ledge 20 circumscribing end cap 17. Ledge 20 extends substantially perpendicularly away from axis 14 and defines a plurality of notches 22 that are substantially symmetrically spaced about axis 14. Ledge 20 has a thickness which is typical of known end caps in the art. A plurality of notches 22 are adapted to be engaged with corresponding features of housing 16, which will be discussed in detail herein below.

[0020] Housing 16 has a first end 24 that corresponds with output end of motor 10 and a second end 26 that is opposed to first end 24. First end 24 of housing 16 has a rim 28 that includes a plurality of locator tabs 30 that is less than or equal to the number of notches 22 on ledge 20 of end cap 17. Locator tabs 30 extend axially from rim 28 in the direction of output shaft 12 and are aligned relative to notches 22 defined by ledge 20 of end cap 17. The height of each locator tab 30 is at least equal to the thickness of ledge 20. Cut out of at least one or more locator tabs 30 are deformable fingers 32 that may be spread apart. Once locator tabs 30 are inserted into corresponding notches 22, fingers 32 are spread apart and over ledge 20, thereby locking end cap 17 onto housing 16 as shown in Fig. 2. Located on either side of locator tabs 30 are indentations 34, best shown in Fig. 1, the significance of which will be further discussed herein below.

[0021] Positioned between rim 28 and ledge 20 are spring clips 11, which are best shown in Figs. 1 and 3. Spring clip 11 includes a motor mounting portion 36 that has a latitudinal segment 38 that is perpendicular to axis 14 and a longitudinal segment 40 that is parallel to axis 14 and housing 16. Latitudinal segment 38 defines an aperture 42 adapted to be slipped over locator tab 30 of housing 16 while a portion of the remaining segment is seated into indentations 34 as shown in Figs. 1 and 2.

[0022] Best shown in Figs. 3 and 4, longitudinal segment 40 includes plastic post mounting portion 37 that includes axial cylinder 44 that defines channel 47 having an initial internal diameter adapted to receive a larger diameter plastic post 13. Shown in Figs. 4 and 5, axial cylinder 44 has an interior wall 46 that defines channel 47 to receive and securely lock onto plastic post 13. Interior wall 46 includes barb 48 and an annular groove 50 to prevent the extraction of plastic post 13 once the post is inserted into spring. Axial cylinder 44 also includes stop 53 to limit the insertion of plastic post 13 to ensure the proper positioning of motor 10. Located on latitudinal segment 38 and continuing to longitudinal segment 40 is slit 52. Slit 52 is biased toward a closed position, which in turn will decrease the internal diameter of axial cylinder 44. Longitudinal segment 40 is adapted to be securely abutted against housing 16 to prevent lateral movement of spring clip 11 due to torsional forces while the motor is in operation, which is best shown in Fig. 2.

[0023] Shown in Fig. 1 is motor attachment assembly 2 having spring clips 11 attached to motor 10 between end cap 17 and housing 16. Motor attachment assembly 2 is shown in Fig. 2 axially spaced apart from plastic post vibration isolation system 19. Vibration isolation system 19 includes motor cup 54 adapted to receive second end 26 of housing 16. Extending axially from motor cup 54 toward output shaft 12 are plastic isolation posts 13. The axial cylinders 44 of spring clips 11 are aligned with plastic post 13 just prior to insertion of plastic post 13 into channel 47 defined by axial cylinder 44. [0024] Shown in Fig. 5, once the plastic post is inserted into channel 47 of spring clip 11, barbs 48 dig into plastic post 13 due to the spring loading of the spring clips and displace the plastic. The plastic initially supports some spring load but begins to flow under stress

into annular groove 50. Over time, the plastic creeps into the annular groove 50 due to the radial pressure exerted on to the plastic post from spring clip 11. The plastic material deforms and plastic creeps into the annular groove 50 forming a tongue 60 to further aid in preventing plastic post 13 from being extricated.

[0025] A typical plastic post, as shown in Fig. 4 is tapered with an outer diameter of 6.2 mm at the tip and an outer diameter of 8.0 mm at the base. Plastic post 13 includes longitudinal grooves 58 that extend along the length of plastic post 13; however, plastic post 13 may also be smooth or molded with other surface features to enhance the gripping effect of spring clip 11. Spring clip 11 for plastic post 13 as shown has a cylindrical portion 56 with an inner diameter of 5.9 mm which is slighter smaller than the 6.2 mm tip outer diameter of plastic post 13. The cylindrical portion 56 of spring clip 11 has a length of 7.2 mm. The spring clip may be fabricated from Grade 1060 to 1080 steel and austemper heat treated to 48-54 HRC equivalent.

[0026] The benefit of the present invention is that it allows for simple press on assembly onto the plastic post once the spring clips are assembled onto the motor. Another benefit of the invention is that it takes advantage of the creep property of plastic to create an interlock.

[0027] While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.