US3031129A - Motor-fan unit mounting for vacuum cleaner - Google Patents

Description

April 24, 1962 E. GAUDRY MOTOR-FAN UNIT MOUNTING FOR VACUUM CLEANER Filed April 1, 1958 2 Sheets-Sheet 1 April 24, 1962 Filed April 1, 1958 E. GAUDRY MOTOR-FAN UNIT MOUNTING FOR VACUUM CLEANER aid g Sheets-Sheet 2 W Arraqwar United States Patent i 3,031,129 MUTUR-FAN UNIT MOUNTING FOR VACUUM CLEANER Edouard Gaudry, Montreal, Quebec, Canada, assignor to Alrtieboiaget Elcctrolux, Stncirholm, Sweden, a corporation of Sweden Filed Apr. 1, 1958, Ser. No. 725,729 1 Claim. (Cl. 230-417) The present invention relates to vacuum cleaners and more particularly to an apparatus for mounting an electric motor in a casing.

It is a common practice to use resilient mountings to suspend a rotating or reciprocating part in a stationary frame or casing. In present day vacuum cleaners the fan motors are usually operated at high speeds to conserve space and unless the motor and fan are perfectly balanced they will produce excessive vibration. To prevent the transmission of such vibration in vacuum cleaners, the motor is usually suspended in its casing by a resilient mounting. Such mountings may be in the form of a rubber annulus between the motor and casing which constitutes the sole support for the motor-fan unit. This type of motor mounting provides an economical structure which absorbs much of the vibration and thereby reduces noise.

However, the weight of the motor-fan unit is apt to produce a looseness in a rubber annulus of the type indicated which permits the unit to cant or tilt at an angle to the axis of the mounting. Such tilting of the motorfan unit accentuates any unbalance and is apt to produce an even greater amplitude of vibration, especially when the motor is started and while it is coming up to speed. Also, the weight of the motor-fan unit is apt to produce a permanent sag in the bearing portion of the mounting annulus which engages the motor-fan unit and permits the unit to wobble in the mounting. When such looseness in the mounting progresses, due to progressive deformation of the material of the mounting, the vibration and resulting noise increases and can only be corrected by replacing the mounting.

One of the objects of the present invention is to provide an improved apparatus for mounting a motor in a casing.

Another object is to provide a resilient rubber mounting for suspending an electric motor in a casing which is pre-stressed in tension to prevent the mounting from sagging or the motor from tilting in the mounting.

Another object is to provide an improved suspension mounting which positively holds an electric motor in a fixed position in a casing while damping the vibration of the motor to reduce noise.

Another object is to provide an improved suspension mounting of the type indicated having rigid rings at its inner and outer peripheries for attachment to the motor and casing and a web of resilient material extending between the rings under tension.

Another object is to provide an improved suspension mounting for an electric motor which is of simple and compact construction, economical to manufacture, and one which is reliable in operation over long periods of time.

These and other objects will become more apparent from the following description and drawings in Which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not a definition of the limits of the invention, reference being had for this purpose to the appended claim.

In the drawings:

FIGURE 1 is a side elevational view of a vacuum 3,d31,12?9 Patented Apr. 24, 1962 ice cleaner partly in section to show the motor mounting incorporating the present invention;

FIGURE 2 is an enlarged longitudinal section view of the motor mounting showing the inner and outer metallic rings embedded in a resilient material forming the mounting annulus and the tensioned web between the metallic rings;

FIGURE 3 is a front elevational view of the mounting annulus and showing the bosses projecting from the outer ring at spaced points around its outer periphery and the annular ribs of resilient material surrounding the bosses; and

FIGURE 4 is an enlarged sectional View of the mounting to show the means for attaching the mounting to the casing and motor, respectively.

Referring to FIGURE 1 of the drawings, the invention is shown applied to a tank type vacuum cleaner 10 comprising a casing 11 having a detachable front end cover 12 and rear end cover 13. The casing 11 is provided with a handle 14, a front wheel 15 and a pair of rear wheels 16. The front wheel 15 is mounted to rotate about a vertical axis as a caster, as well as about a horizontal axis, to adapt the cleaner to be turned.

The front end cover 12 is removably secured to the casing 11 in any suitable manner and formed with an inlet opening 18 to which a suction hose (not shown) is adapted to be removably connected. Suitable cleaning appliances may be connected to a wand which, in turn, is connected to the outer free end of the suction hose and through which air flows into the casing. A dust bag 19 is mounted in the casing 11 at the rear of the front end cover 12 which acts to separate dust from the air as it flows therethrough.

Flow of air through casing 11 is elfected by a motorfan unit 20 which includes a centrifugal fan 21 carried at one end of an electric motor 22. The fan 21 receives air which passes through the dust bag 19 and the air is discharged from the fan through the motor 22 and eventually passes through an air outlet opening 23 in the rear end cover 13. Motor 22 is connected by conductors 24 to an electric switch 25 which is actuated by a push button 26 located at the top of the casing 11.

In accordance with the present invention, the motorfan unit 20 is suspended in casing 11 by an improved apparatus to provide a resilient mounting for the motor-fan unit and a seal between the high and low pressure sides of the fan. The improvement comprises prestressing an annulus of an elastomeric material in tension between its inner and outer peripheries and attaching the peripheries to the casing 11 and motor-fan unit 20, respectively. The elastomeric material may comprise any suitable resilient substance such as natural or synthetic rubber or other rubber-like plastics. Thus, the term rubber as hereinafter used in the specification is intended to include other rubber-like plastics. Preferably, the rubber annulus is formed with enlarged inner and outer peripheral rims for sealing attachment to the casing and motor-fan unit, respectively, and a thinner impervious web therebetween which is pre-stressed in tension between the casing and motor.

The resilient mounting pre-stressed in tension between the casing and motor in accordance with the method in the present invention restrains the motor-fan unit from tilting while damping and absorbing vibration. Furthermore, the material of the mounting annulus does not sag or become permanently deformed over long periods of time whereby to maintain the amplitude of vibration at a low level. The impervious rubber annulus in sealing engagement with the motor and easing also acts to prevent leakage of higher pressure air from the fan outlet around the motor-fan unit to the fan inlet.

The form and mass of the mounting annulus should be designed to have a natural period of vibration which is less than the period of the disturbing force such as the inherent period of vibration of the motor-fan unit. The primary disturbing force produced by the motor usually results from its electrical characteristics such as the frequency of alternating current supplied. Therefore, the natural period of vibration of the resilient mounting annulus should be one which is not a multiple of the current frequency. For example, if a 60 cycle alternating current motor is used, the rubber annulus should be designed to have a natural period fo vibration about 30% below the period of vibration of the disturbing force. Under such conditions, an ideal natural period of vibration of the resilient mounting annulus would be 43 cycles per second.

The resilient mounting annulus may have a number of different structures and may be pre-stressed in a number of different ways. For example, the outer periphery of the mounting annulus may be clamped between a pair of outer rings and its inner periphery drawn inwardly toward the axis to stretch the web therebetween and then clamped between another pair of inner rings. In another form, the mounting annulus may be formed with annular grooves in its inner and outer rims and the web stretched radially to engage the grooves in the rims with the inner and outer rigid rings.

Preferably, the intermediate web of the annular mounting annulus is pre-stressed by molding the rubber around and between inner and outer rigid rings. The molded rubber shrinks as it sets in the mold and during curing to pre-stress the web in tension. As the rings embedded in the molded rubber hold the inner and outer peripheries of the annulus, the shrinkage occurs uniformly between the rings to pre-stress the web of the mounting in tension. While the composition and mass of the rubber material and the shape of the annulus will vary the tension applied to the web, these factors can be controlled by the particular design to produce the tension required for a motorfan unit of a particular weight to prevent sagging in the web or tilting of the motor-fan unit in the mounting.

The resulting mounting is illustrated in the drawings as comprising a mounting annulus of rubber having enlarged inner and outer rims 31 and 32 with metallic rings 33 and 34 embedded therein and a relatively thin web 35 tensioned therebetween. In the illustrated embodiment, the inner and outer metallic rings 33 and 34 are of oval shape in cross section, see FIGURE 2, to increase their hoop strength. The outer metallic ring 34 is provided with opposed pairs of laterally projecting bosses 36 and 37 arranged in spaced relation around its periphery which extend to the sides of the rubber rim 32. Each pair of aligned bosses 36 and 37 has a hole 38 through which attaching screws may be inserted. Spaced annular rubber ribs 40 and 41 of rubber are molded as an integral part of the mounting annulus 30 and project from one side thereof adjacent the sides of the holes 38 in the bosses 36.

As shown in FIGURES 1 and 4, the inner rim 31 of the resilient mounting 30 is attached to the motor 22 while the outer rim, 32 is attached to the casing 11. As shown most clearly in FIGURE 4, the inner rim 31 is clamped in an annular channeled seat 42 in the motor housing which is located at its approximate center of gravity. The annular channeled seat 42 is formed at one side by stepped vertical shoulders 43 and 44 on the motor housing and on the other side by a clamping ring 45. Clamping ring 45 has a radial flange 48 forming a clamping face 46 opposite the face formed by the shoulder 43 an an annular horizontal flange 47 underlying the shoulder. The inner rim 31 of the resilient mounting 30 is clamped between the faces 43 and 46 of the motor housing and clamping ring 45 by means of screws 48. As the screws 48 are tightened to draw the clamping ring 45 toward the annular shoulder 43 of the motor 22, the rim 31 of the molded rubber annulus 30 is compressed therebetween to tightly and positively grip the mounting an nulus to the housing of the motor 22 with a resilient cushion between the metallic parts. The compression of rim 31 is controlled by the engagement of the end of the horizontal flange 47 of the clamping ring '45 with the stepped oflset shoulder 44 on the housing of the motor 22 which acts as a stop.

The outer rim 32 of the resilient mounting 30 is tightly and positively clamped to an inwardly projecting flange 49 on the casing 11 by means of the screws 50. The flange 49 may be of any desired form and attached to the casing 11 in any desired way. In the illustrated embodiment, flange 49 projects inwardly from a bracket 51 having a forwardly projecting flange 52 which may be attached to the casing 11 as by welding it hereto. It will be observed that the heads of screws 50 directly bear against the bosses 37 of the metallic ring to provide a metal to metal contact. However, the spaced rubber ribs 40 and 41 projecting from the side of the mounting annulus 30 engage the flange 49 on casing 11 to provide a resilient cushion between the embedded metal ring 34 and bracket 43 to which the annulus is attached.

Thus, the resilient mounting annulus 30 has inner and outer metallic rings 33 and 34 for attachment to the motor 22 and casing 11, respectively, and with a web 35 extending between the rims and pre-stressed in tension. Furthermore, it will be observed that the molded rubber surrounds each of the metallic rings 33 and 34 and provide a resilient cushion between the rings and the parts to which they are attached. One form of resiliently mounting having now been described in detail, its mode of operation is explained below.

The mounting annulus 30 is first mounted on the annular flange 47 of the clamping ring 45 and the clamping ring applied in position on the housing of the electric motor 22. The clamping ring is then attached to the housing of the motor 22 by inserting the screws 48 through holes in the clamping ring and screwing them into tapped holes in the motor casing. The tightening of the clamping ring 45 is controlled by the engagement of the forward end of its horizontal flange 47 with the offset shoulder 44 on the housing of the motor 22. The clamping ring 45 positively and tightly clamps the rim 31 of the annulus to the motor housing while providing a cushion of rubber between the embedded metallic ring 33 and the housing.

The motor-fan unit 22 with the mounting ring 30 attached thereto is then inserted in the casing 11 until the outer rim 32 of the annulus 30 engages the inwardly directed annular flange 49 of the bracket 51. The motorfan unit 20 is then turned until the holes 38 in the outer periphery of the rim 32 align with the tapped holes in the flange 49 in the bracket 51. Screws 50 are then inserted through the holes 38 and screwed into the tapped holes of flange 49 to mount the motor-fan unit in the casing.

Due to the pre-stressing of the web 35 of mounting 30 in tension, the motor-fan unit 20 is held in its proper axial position in the casing 11. When the vacuum cleaner is operated by depressing the push button 26 of the elec tric switch 25, the motor rotates on its horizontal axis with a minimum of vibration. The vibration produced by the motor 22 is then absorbed by the rubber of the mounting toprevent transmission to the casing 11 and excessive noise. With a properly designed mounting 30 having a natural frequency of vibration which is less than the disturbing force produced by the motor 22 and an indivisible component of the frequency of the disturbing force, the amplitude of the vibration is maintained at a minimum. Furthermore, the mounting annulus 3t] provides an impervious septum between the motor-fan unit 20 and casing 11 to seal theair outlet of the fan from its air inlet.

It will now be observed that the present invention provides an improved apparatus for resiliently suspending an electric motor in a casing and provides a seal between the inlet to and outlet from the fan. It will also be observed that the present invention provides a mounting of a resilient material which is pre-stressed in tension between the casing and motor to hold the latter in its proper horizontal axis without sagging or deformation of the resilient material of the mounting. It will also be observed that the present invention provides a suspension mounting for an electric motor which damps the vibration produced by the motor to reduce the noise. It will further be observed that the present invention provides an improved resilient mounting for an electric motor having inner and outer rings embedded in molded rubber with a web of resilient material pre-stressed in tension therebetween. It will still further be observed that the present invention provides an improved mounting which is of simple and compact construction to adapt it for economical manufacture and one which is reliable in operation for long periods of time.

While a single embodiment of the invention is herein illustrated and described it will be understood that modifications may be made in the constructions and arrangements of elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect, the invention is defined by the following claim:

In a vacuum cleaner, a casing having air inlet and outlet openings, 21 motor-fan unit in the casing between said inlet and outlet openings and constructed to pass air therethrough, a combined resilient mounting and diaphragm for suspending the motor-tan unit in. the casing and separating the casing into inlet and outlet chambers comprising an annulus of elastomeric material having inner and outer rims, a rigid ring completely embedded in the elastomeric material around its entire periphery at the inner rim of the annulus, a second rigid ring completely embedded in the elastomeric material around its entire periphery at the outer rim of the annulus, said annulus having an imperforate web between the inner and outer rims prestressed in tension and together with the rims forming the diaphragm dividing the easing into the air inlet and outlet chambers at opposite sides of the motor-fan unit, and means for attaching the inner and outer rims of the annulus having the rigid rings embedded therein to the motor-fan unit and casing, respectively whereby the prestressed web of the annulus tends to retain the motor-fan unit in position, reduce vibration and noise and provide a seal between the casing and motorfan unit.

References Cited in the file of this patent UNITED STATES PATENTS 1,996,210 Lord et a1 Apr. 2, 1935 2,230,595 Horton Feb. 4, 1941 2,236,265 Hansson et al Mar. 25, 1941 2,241,870 Schribner May 13, 1941 2,307,066 Paulus Jan. 5, 1943 2,328,038 Taylor Aug. 31, 1943 2,349,215 Wahlborg May 16, 1944 2,387,066 Harding Oct. 16, 1945 2,578,730 Nicholson et al Dec. 18, 1951 2,628,416 Sampson Feb. 7, 1953 2,670,896 Ardito Mar. 2, 1954 2,780,826 Coons, et al. Feb. 12, 1957 2,875,466 Nyberg Mar. 3, 1959 2,888,232 Kroeger May 26, 1959 2,889,570 Duii June 9, 1959 FOREIGN PATENTS 639,366 Great Britain June 28, 1950

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