Methods of making torsional vibration isolating motor mounting systems and arrangements

Abstract

Disclosed subject matter includes flexible motor mounting members particularly adapted for vibration induced flexing movement combined with oscillatory movement about a pivot axis at a point of attachment on a blower housing or other support. Short but strong mounting members are provided that have low torsional mode vibration transmissibilities. Leaf spring mounting arms have low torsional spring constants and yet have sufficient strength to withstand shipping and handling loads for motor .Iadd.blower .Iaddend.assemblies and to permit all angle motor mounting. The mounting member spring constants for axial, radial and tilting vibration modes are selected in specific forms so that the characteristic vibration transmissibility ratios for these modes are each close to unity. However, the characteristic torsional mode vibration transmissibility is substantially less than unity. In particularly preferred embodiments of the invention, sheet steel having a martensitic grain structure is utilized to form the mounting members. Bends in this material have a radius of at least seven times the thickness of the material. One method includes forming lugs or mounting members from the selected material and then trapping one end of these members between oppositely facing surfaces of fastening members. In some forms, the motor shell constitutes one fastening member and a holding plate is another fastening member.Iadd., .Iaddend.and it is preferred to capture a motor pad portion of the lug against the motor shell and projection weld the projections from the plate to the motor shell. The free end of the lug is specifically configured to prevent deformation and tearing, and the lugs are extremely easy to mount to a blower housing imply by deflecting the mounting arms (when necessary) with finger pressure so as to align holes in the mounting arms with previously provided holes in the blower housing. In another form, the motor end of mounting lugs are trapped between two pieces of steel that are welded together to form a mounting block having a strap accommodating slot therein.

What I claim as new and desire to secure by Letters Patent of the United States is: 
     
       1. A method of manufacturing a torsional mode vibration isolating motor mounting system comprising a stationary motor member oriented along a longitudinally extending axis and a plurality of martensitic steel flexible motor supporting arms particularly adapted for supporting an induction motor, including the motor member, from a plurality of locations along a mounting structure and for establishing a torsional mode resonant frequency for the arrangement of less than √2 times the motor power supply frequency, and a tilting mode resonant frequency greater than twice the motor power supply frequency; wherein at least one of said arms has a radially extending portion of generally rectangular cross-section and also has a pre-selected thickness less than the width thereof, and wherein the at least one of said arms further has a motor mounting tab, said method comprising: positioning said at least one of said arms with the radially extending portion thereof oriented so that the thickness thereof is oriented in a direction generally transversely relative to the longitudinally extending axis, so that the width thereof is oriented in a generally parallel direction relative to the longitudinally extending axis, and so that the motor mounting tab thereof is closely adjacent to the stationary motor member, and positioning at least one weldable projection along a projection accommodating portion of the tab and positioning a mass of heat absorbing and tab reinforcing material adjacent to the tab with the tab sandwiched between the stationary motor member and mass of heat absorbing and tab reinforcing material so as to establish, with the motor member, heat sink means; welding the mass of heat absorbing and tab reinforcing material to said stationary motor member by passing welding current through the at least one projection; and dissipating welding heat caused by the welding current through the motor member and mass of heat absorbing and tab reinforcing material whereby excessive heating of the at least one of said arms due to the welding heat is avoided. 
     
     
       2. The method of claim 1 wherein dissipating welding heat comprises transferring heat to the mass of heat absorbing and tab reinforcing material and to the stationary motor member during the welding step, thereby to avoid destruction of the martensitic characteristics of the at least one of said arms. 
     
     
       3. The method of claim 2 wherein the mass of heat absorbing and tab reinforcing material includes two weldable projections and the step of welding includes relatively positioning electrodes respectively adjacent to the motor member, and to the mass of heat absorbing and tab reinforcing material. 
     
     
       4. A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement comprising first and second weldable members that cooperate as heat sink means, and a flexible mounting arm having a motor end with projection accommodating means therein, said method comprising: positioning together the flexible mounting arm, the first weldable member, and the second weldable member, and trapping the motor end of the flexible mounting arm between the first and second weldable members with at least one weldable projection on the second weldable member accommodated by the projection accommodating means of the mounting arm; engaging the first and second weldable members with electrodes, relatively urging the first and second weldable members toward one another, passing welding current through the first and second weldable members thereby to weld the at least one projection to the first weldable member at an interface therebetween, and dissipating welding heat caused by the welding current along the heat sink means .[.whereby.]. .Iadd.to avoid .Iaddend.excessive heating of the mounting arm .[.is minimized.].. 
     
     
       5. The method of claim 4 wherein the first weldable member is the shell of the motor; the second weldable member and the shell of the motor cooperate as heat sink means, and the flexible mounting arm is formed from martensitic steel. 
     
     
       6. .[.The method of claim 4.]. .Iadd.A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement comprising first and second weldable members that cooperate as heat sink means, and a flexible mounting arm having a motor end with projection accommodating means therein, said method comprising: positioning together the flexible mounting arm, the first weldable member, and the second weldable member, and trapping the motor end of the flexible mounting arm between the first and second weldable members with at least one weldable projection on the second weldable member accommodated by the projection accommodating means of the mounting arm; engaging the first and second weldable members with electrodes, relatively urging the first and second weldable members toward one another, passing welding current through the first and second weldable members thereby to weld the at least one projection to the first weldable member at an interface therebetween, and dissipating welding heat caused by the welding current along the heat sink means whereby excessive heating of the mounting arm is minimized; .Iaddend.wherein the first weldable member and second weldable member together comprise, after welding of the projection, a block having a slot therethrough; and the method further comprises threading a strap through the slot. 
     
     
       7. The method of claim 6 further comprising: fastening the strap to a motor and thereby fastening the block and flexible arm to the motor. .Iadd. 
     
     
       8.  A method of manufacturing a torsional mode vibration isolating motor mounting system comprising a stationary motor member oriented along a longitudinally extending axis and a plurality of martensitic steel flexible motor supporting arms particularly adapted for supporting an induction motor, including the motor member, from a plurality of locations along a mounting structure; wherein at least one of said arms has a radially extending portion of generally rectangular cross-section and also has a pre-selected thickness less than the width thereof, and wherein the at least one of said arms further has a motor mounting end, said method comprising: positioning said at least one of said arms with the radially extending portion thereof oriented so that the thickness thereof is oriented in a direction generally transversely relative to the longitudinally extending axis, so that the width thereof is oriented in a generally parallel direction relative to the longitudinally extending axis, and so that the motor mounting end thereof is closely adjacent to the stationary motor member, and positioning a mass of heat absorbing and motor mounting end reinforcing material adjacent to the motor mounting end with weldable portions of the mass in close proximity with the stationary motor member for being welded thereto, and with the motor mounting end sandwiched between the stationary motor member and mass of heat absorbing and reinforcing material so as to establish, with the motor member, heat sink means; welding the mass of heat absorbing and reinforcing material to said stationary motor member by passing welding current through the weldable portions; and dissipating welding heat caused by the welding current through the motor member and mass of heat absorbing and reinforcing material whereby excessive heating of the at least one of said arms due to the welding heat is avoided. .Iaddend. .Iadd.9. The method of claim 8 wherein dissipating welding heat comprises transferring heat to the mass of heat absorbing and reinforcing material and to the stationary motor member during the welding step, thereby to avoid destruction of the martensitic characteristics of the at least one of said arms. .Iaddend. .Iadd.10. The method of claim 9 wherein the mass of heat absorbing and reinforcing material includes two weldable projections and the step of welding includes relatively positioning electrodes respectively adjacent to the motor member, and to the mass of heat absorbing and reinforcing material. .Iaddend. .Iadd.11. A method of manufacturing a torsional mode vibration isolating mounting system for a motor comprising a stationary motor member oriented along a longitudinally extending axis and a plurality of martensitic type steel flexible motor supporting arms particularly adapted for supporting an induction motor, including the motor member, from a plurality of locations along a mounting structure; wherein at least one of said arms has a radially extending portion of generally rectangular cross-section and also has a pre-selected thickness less than the width thereof, and wherein the at least one of said arms further has a motor mounting end, said method comprising: positioning said at least one of said arms with the radially extending portion thereof oriented so that the thickness thereof is oriented in a direction generally transversely relative to the longitudinally extending axis, so that the width thereof is oriented in a generally parallel direction relative to the longitudinally extending axis, and so that the motor mounting end thereof is closely adjacent to the stationary motor member such that when the motor end is held fast with the motor member the motor and mounting system have a torsional mode natural frequency of less than 2 times the motor power supply frequency, and a tilting mode natural frequency that is at least three times greater than an expected fundamental forcing frequency, and positioning a mass of heat absorbing and reinforcing material adjacent to the motor mounting end, with weldable portions of the mass in close proximity with the stationary motor member for being welded thereto, and with the motor mounting end sandwiched and fastened between the stationary motor member and mass of heat absorbing and reinforcing material so as to establish, with the motor member, heat sink means; welding the mass of heat absorbing and reinforcing material to said stationary motor member by passing welding current through the weldable portions; and dissipating welding heat, caused by the welding current through the motor member and mass of heat absorbing and reinforcing material, by transferring heat from the mass of heat absorbing and reinforcing material to the stationary motor member during the welding step, whereby excessive heating of the at least one of said arms due to the welding heat is avoided, thereby to avoid destruction of martensitic type steel strength characteristics of the at least one of said arms. .Iaddend. .Iadd.12. A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement comprising first and second weldable members that cooperate as heat sink means, and a flexible mounting arm having a motor end with projection accommodating means therein, said method comprising: positioning together the flexible mounting arm, the first weldable member, and the second weldable member, and trapping the motor end of the flexible mounting arm between the first and second weldable members with at least one weldable projection on the second weldable member accommodated by the projection accommodating means of the mounting arm; and passing welding current through the first and second weldable members thereby to weld the at least one projection to the first weldable member at an interface therebetween, and dissipating welding heat caused by the welding current along the heat sink means whereby excessive heating of the mounting arm is minimized; said first weldable member and second weldable member together comprising, after welding of the projection, a block having a slot therethrough; and said method further comprising threading a strap through the slot. .Iaddend. 
     
     
        .Iadd.13.  The method of claim 12 further comprising: strapping the trapped end of the flexible arm to the motor. .Iaddend. .Iadd.14. A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement for a motor having a circumferentially extending shell and a shaft extending along a rotational axis from within the confines of the shell, the arrangement comprising first and second weldable members that cooperate as heat sink means with the first one of said weldable members being a circumferentially extending body, and a flexible mounting arm having a length, width, and thickness formed from a martensitic type of steel having a motor end, said method comprising: positioning together the flexible mounting arm, with the first weldable member relatively oriented so that the length of the arm extends radially away from the first member for mounting to a mounting structure and so that the thickness of the arm is oriented transversely with respect to the direction along which the axis of the motor extends, the first weldable member, and the second weldable member, and trapping the motor end of the flexible mounting arm between the first and second weldable members with spaced apart regions of the second weldable member located in close proximity to the first weldable member, passing welding current through the first and second weldable members, while relatively urging the first and second weldable members toward one another, thereby to weld the spaced apart regions of the second weldable member to the first weldable member at an interface therebetween, and dissipating welding heat caused by the welding current along the heat sink means whereby excessive heating of the mounting arm is minimized. .Iaddend. .Iadd.15. The method of claim 14 wherein the first weldable member is the shell of the motor; the second weldable member and the shell of the motor cooperate as heat sink means; and the flexible mounting arm has a length, width, and thickness with said length and thickness positioned parallel to the motor axis with said motor end bent to lie generally along the motor shell such that when said members are welded together the torsional mode resonant frequency for the arrangement is less than √2 times the motor power supply frequency, and the tilting mode vibration transmissibility ratio is close to unity. 
     
     
        .Iaddend. .Iadd.16.  A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement comprising first and second weldable members that cooperate as heat sink means, and a flexible mounting arm formed from a martensitic type of steel and having a motor end, said method comprising: positioning together the flexible mounting arm, and first and second weldable members, and trapping the motor end of the flexible mounting arm between the first and second weldable members; passing welding current through the first and second weldable members while urging the first and second weldable members toward one another, thereby to weld the first and second weldable members together at at least two spaced apart interfaces therebetween, and dissipating welding heat caused by the welding current along the heat sink means whereby excessive heating of the mounting arm is minimized, thereby to avoid destruction of the martensitic type of steel strength characteristics of the mounting arm. .Iaddend. .Iadd.17. The method of claim 16 wherein the first weldable member is the shell of the motor; the second weldable member has at least two spaced apart regions that are welded to the shell, the motor end of the arm accommodates the two spaced apart regions along two edges thereof, and the method further comprises locating the motor end of the arm and second weldable member in predetermined locations relative to each before welding together the first 
     
     
        and second weldable members. .Iaddend. .Iadd.18.  A method of manufacturing a torsionally flexible vibration isolating electric motor mounting arrangement comprising first and second weldable members that cooperate as heat sink means, and a flexible mounting arm formed from a martensitic type of steel and having a motor end, said method comprising: positioning together the flexible mounting arm, the first weldable member, and the second weldable member, and trapping the motor end of the flexible mounting arm between the first and second weldable members with at least one weldable portion of the second weldable member accommodated by the mounting arm; passing welding current through the first and second weldable members, while urging the first and second weldable members toward one another, thereby to weld the at least one weldable portion of the second weldable member to the first weldable member at an interface therebetween, and dissipating welding heat caused by the welding current along the heat sink means whereby excessive heating of the mounting arm is minimized, thereby to avoid objectionably affecting the martensitic steel strength characteristics of the mounting arm. .Iaddend.