GB2089463A - Pulley arrangement for suction cleaners - Google Patents

Abstract

A suction cleaner has an agitator (56) which is driven through a belt drive arrangement which includes an idler pulley system and a pair of belts 48, 54. The idler pulley system (50, 52) is pivoted so as to permit the two belts (48, 54) to stretch and properly track during normal operation of the cleaner. One belt (48) which may be the flat belt is of elastomeric material while the second belt (54) is a 'V' belt of relatively inextensible composition. One belt (48) is driven directly by a motor shaft (46), this belt extending to the idler pulley system with the second belt (54) extending from the idler pulley system to the agitator (56). <IMAGE>

Description

SPECIFICATION Pulley arrangement for floor care devices This invention relates to floor care devices having a driven floor engaging tool. The present invention has as one of its objects the provision of an idler pulley and belt drive arrangement wherein slippage of one of two belts prevents rotor stall of the floor care device motor.

According to the present invention, a floor care device comprises a floor engaging tool arranged to be driven by a motor having a shaft through a belt drive and an overload arrangement including an idler pulley structure, a first belt passing around the idler pulley structure and the motor shaft, and a second belt passing around the idler pulley structure and the tool, one of the belts being relatively unstretchable compared to the other belt and the idler pulley structure being mounted so as to be movable towards and away from the motor shaft. When the floor engaging device encounters severe resistance to its rotation, or is prevented from rotating, one of the belts is able to slip by movement of the idler pulley structure towards or away from the rotor shaft.This prevents the rotor shaft from stalling by loosening and slipping of one of the belts, thereby avoiding possible damage to the motor. It also substantially eliminates broken or burned through belts. The moveable pulley structure permits at least one of the belts to stretch thus permitting the belts to properly track during normal operation of the floor care device.

Preferably the motor is resiliently mounted on the body of the floor care device and the idler pulley structure is movably mounted on the motor, and may be pivotally mounted on the motor by an arm. The axis of rotation of the motor shaft is maintained in a fixed relationship with the idler pulley structure to permit the belt passing around the drive shaft and the idler pulley to track properly, even though the motor may move on its resilient mounts.

Preferably, the first belt has a generally flat cross-section and the second belt has a generally V-shaped cross-section and the second belt is relatively unstretchable compared to the first belt.

This allows the first belt to stretch to permit the Vshaped belt to become slack and slip upon loading of the V-shaped belt by a tool stall. It is felt that this occurs because the flat belt has a non-linear deflection curve so that as the load on it increases the increment of stretch increases at a greater rate, than linearly. At the same time the relatively unstretchable V- belt has a linear deflection characteristic. Thus as the flat belt tends to stretch a greater amount than the V-belt, this causes the idler pulley structure to move towards the tool to cause the V-belt to become slack and sip on the idler pulley stucture and prevent stall at the motor shaft.

The first belt could be made of ethylene propolene diene monomer and the second belt could be a fibre re-inforced with polyester filaments.

The action of the belts and idler pulley structure during tool stall could also occur because of the relative coefficients of friction of the V-belts and the flat belt and the difference of force transmitted at the idler pulley structure.

Preferably, the diameter of the portion of idler pulley structure around which the first belt passes is greater than the diameter of the portion of the idler pulley structure around which the second belt passes, and the diameter of a portion of the tool around which the second belt passes may be greater than the portion of the idler pulley structure around which the second belt passes.

With these arrangements a considerable step down may be achieved to permit the roller to rotate slowly relative to the drive shaft of the motor.

The invention is particularly applicable to suction cleaners having an agitator as a floor engaging tool.

The invention may be carried into practice in various ways, but one specific embodiment will now be described by way of example in which: FIGURE 1 is a plan view of the main body of a suction cleaner with the hood broken away to show many of the operating components of the cleaner; FIGURE 2 is an elevational side view of the pulley drive system and the respective vibration isolators; and FIGURE 3 is a perspective view of the motor, idler pulley system, and associated parts.

The cleaner generally consists of a cleaner main body 10 covered by a hood 12 (shown fragmentarily) wheel height adjustment means 14, a handle release 1 6 and a switch pedal 18 provided for on and off operation of the cleaner.

All of these elements may be substantially conventional so no further description of them is offered.

The motor-fan system 20 includes bellows like isolation means 22 and 24 which communicate, respectively, with a duct 26 which extends forwardly to the agitator aperture (not shown) in the cleaner main body 10 and to a bag flange 28.

Thus, the motor-fan system 20 is resiliently connected to the air delivery and vacuum system on the cleaner.

The motor-fan system 20 is also isolated vibrationally from the cleaner main body 10 adjacent its centre of gravity by a pair of resilient mounts 30 and 32 which are received in a pair of bosses 34 and 36 fixed to the motor-fan system 20 and upwardly extending tabs 38 and 40 having a bore not shown and an open slot 42 therethrough respectively which receive one of the threaded stud ends of each of the suppressors with the suppressors attached thereto by nuts 44, 44. The ends of the mount adjacent bosses 34 and 36 thread into these bosses. The vibration isolation mounts 30 and 32 can be seen in Figure 3 to comprise central enlarged cylindrical isometric portions 31, 33 into whose ends have been mouldably mounted threaded stud means so as to provide for the easy mounting of these vibration isolation mounts for isolation purposes.

The mounts are substantially conventional and widely obtainable from a variety of commercial sources.

At the motor end of the motor-fan system 20 (to the right of Figure 1) is a motor shaft 46 extending sidewardly towards the edge of the cleaner main body 10. An elastomeric belt 48 of flat, generally stretchable nature is mounted on this shaft and extends forwardly to be entrained at its other end around a pulley 50, this belt tensions the system. The diameter of the pulley 50 is larger than the diameter of the shaft 46 so a speed reduction occurs between the shaft 46 and a hub 51 which integrally mounts the pulley 50.Integral with the pulley 50 is a smaller pulley 52 that trains a fiber reinforced V-belt 54 of relatively unstretchable nature of high load bearing characteristics, that, in turn, extends forwardly so as to train around an agitator 56 (see Figure 2) having a larger diameter to drive it at a much reduced speed than the rotational velocity experienced by the motor shaft 46. This reduced speed or rotation of the agitator 56 provides a cleaner having a lower noise output based on the reduced noise generated by the slowed agitator and its beater bars and/or brushes.

The integral pulleys 50, 52 are journalled on an axle 60 which carries on each side of the pulleys a sleeve 61 and a washer 62 and which serves as a bearing means for rotation of the integral pulleys 50 and 52. This axle may be slightly skewed towards the motor shaft 46 to provide an automatic take up when belt loaded. As shown in Figure 3, at its one end, the axle 60 has a washer 58 and an E-ring 64 mounted thereover, with the E-ring 64 mounted in a peripheral groove 65 in the axle 60 to prevent movement of the integral pulleys 50, 52 off the end of the axle 60. The axle 60 is anchored at its other end by means of a bore 66 in a support bracket 68 of general L-shaped configuration with a planar surface 69 on the end of the horizontally extending leg of the L.The bore 66 is disposed in an upper leg 71 of the L with the shaft 60 placed therethrough and a threaded end 70 engaged by a nut 72 to maintain the axle 60 in position for rotatably journalling the pulleys 50 and 52.

The bracket 68 is pivotally mounted relative to the motor-fan system 20 so as to permit alignment of the belts 48 and 54 over their respective pulleys so that the same may generally equalise their tensions, train properly and provide a rotational driving force to the agitator 56. This pivoting is occasioned by a shaft 74 which extends through a pair of aligned bores 78, 87 in the horizontally extending leg of the bracket 68 and a bracket 86 respectively. The support bracket 68 is prevented from sliding off the end of shaft 74 by means of an E-ring 80 which nests in a peripheral groove 82 adjacent the end of the shaft 74. Thus, the support bracket 68 is mounted pivotally for the smooth running of the belts 48 and 54.

In order to maintain a constant axis of rotation of the shaft 74, relative to the axis of rotation of motor shaft 46 of motor-fan system, the shaft 74 is mounted therewith so that movement of the motor-fan system 20 on its resilient mounts 30 and 32 will not tend to misalign the axis of motor shaft 46 and the axis of the pulley 50. Thus, the flat elastomeric belt tends to track properly completely independently of the movement of the motor-fan system 20 relative to the cleaner main body 10. This relative positioning is fairly critical since the use of a flat belt requires a more positive tracking arrangement than the use of the V-belt such as that that extends forwardly to the agitator 56.

As shown in Figure 3 the means for mounting the shaft 74 on the motor-fan unit 20 comprises an integral lug 84 extending radially outwardly from the housing of the motor-fan unit 20 and having a through bore 85 therein to receive a portion of the shaft 74 in a nested relationship.

The shaft 74 extends outwardly and sidewardly from this retension means to extend through a hole 87 in a bracket 86 fixed to the motor-fan system 20 and then through the bore 78 in the bracket 68. An E-ring 88 contacts the shaft 74 in a groove (not shown) on the inward side of the bracket 86 so that it and the E-ring 80 maintains the shaft 74 in its desired position with the bottom portion of the leg 71 abutting the side of the bracket 86 adjacent the bore 87. At the same time, the bracket 86, through a pair of bolts 90 and 92 which attach threadingly to a pair of lugs 94 and 96 fast with the motor housing, ensure that the shaft 74 moves as the motor-fan unit 20 moves on its resiient mounts.Then the pulley 50 tracks properly with the elastomeric flat belt 48 relative to the motor shaft 46 due to the pivotal motion of the support bracket 68 on a fixed centre relative to the motor shaft 46.

The vibration isolation at the motor shaft end of the motor-fan system 20 will now be detailed. The bracket 86 mounts one end of a pair of resilient mounts 98, 100 which are smaller in size than the resilient mounts 30 and 32 but have a similar construction. This is accomplished by a pair of integral sidewardly and outwardly extending lugs 102 and 104 disposed at the upper and lower reaches of the bracket 86 having, respectively, bores 106 and 108, for reception of one end of each of the resilient mounts 98 and 100. A pair of nuts 110 and 112 are screwingly threaded on the threaded studs of the resilient mounts 98 and 100 to pull the same against the inside surface of the lugs 102 and 104. The bracket 86 then and the attached resilient mounts 98 and 100 form the isolation barrier between the attached motor-fan unit 20 and the cleaner main body 10 (by the utilisation of a second bracket 111).

The bracket 111 includes a pair of sidewardly and inwardly extending tabs 112 and 114 with a corresponding pair of bores 116 and 118 through which the other threaded sides of the resilient mounts 100 and 98 extend. Nuts 120 and 122 thread on the threaded studs extending from the resilient mounts 100 and 98 to pull these mounts against the facing sides of the inwardly extending tabs 112, 114. The bracket 111 is secured to the main body 10 by the means of a bolt 124 that extends through a bore 128 in a sidewardly extending tab 126 integral with the bracket 111 into a post 127 (see Figure 2) upwardly extending from the major portion of the main body 10. This arrangement secures a portion of the bracket 111 relative to the main body 10.A second bore 128 extends through an inwardly horizontally extending tab 130, integral with the bracket 111 to receive a second screw 1 24 to be engaged in an upwardly extending post 132 (see Figure 2) integral, but upwardly disposed relative to the base portion of the main body 10.

The operation of the resilient damping system for the motor-fan unit 20 may now be easily ascertained. The motor-fan system 20 is resiliently mounted and vibration isolated by the resilient mounts 30 and 32 at its general centre of gravity.

At the same time because of the pull of the flat belt 48 on the motor shaft 46, the motor-fan unit 20 tends to cant forwardly. However, this moves the bracket 86 forward since it is fixed relative to the motor-fan unit 20 so placing a compressive force on the resilient mounts 100 and 98 as the they react against the bracket 111 fixed to the main body 10. This arrangement, then, tends to vibrationally isolate the motor-fan unit 20 at its belt end from the main body 10 and at the same time provides a resilient compressive force by means of the resilient mounts 100 and 98 tending to stretch the belts 48 and 54 so that they may transmit a maximum amount of power to the agitator 56.

It will be appreciated that the invention provides vibration isolation for a cleaner motor-fan system utilising an agitator drive and that the invention can take many forms and that the embodiment illustrated and described is exemplary only.

The flat elastomeric belt 48 utilised was composed of an ethylene propolene diene monomer and had a width of .450 inch (assembled), a thickness of 0.85 inch (assembled) and a length of 10.259 inches measured on the inside (assembled). The V-belt 54 utilised was a fiber belt reinforced with polyester filaments. It has a width of .250 inch, a thickness of .156 inch and an outside length of 16.000 inches. It is available commercially in the U.S.A. as a Light Duty Standard V-belt, 2L--160.

The motor shaft diameter was .315 inch. The idler pulley diameters 50 and 52 where respectively 2.080 inch and 1.200 inch, and the agitator pulley diameter was 1.655 inches. The belts were statically loaded to 300-350 oz.

initially. The centre to centre distance from the motor shaft to the idler pulley assembly was 3.123 inches. Centre to centre distance from the idler pulley to the agitator pulley assembled was 5.77 inches.

The operation of the idler pulleys 50, 52 and belt system 48, 54 for the motor-fan unit 20 can now be easily ascertained. Since the shaft 74 is mounted with the motor-fan unit 20 and the bracket 68 which mounts the pulley 50, 52 is also mounted with the motor-fan unit 20, movement of the motor-fan unit 20 in its resilient vibration isolation arrangement is fully accomodated by the sytem, the centre to centre distance between the shaft 74 and the motor shaft 46 remaining constant. This tends to ensure that the flat belt 48 remains aligned and properly tracking, the alignment of such a flat belt being much more critical than that of the alignment of the V-belt 54.

As was mentioned earlier, the deflection characteristics of the elastomeric belt 48 and the relatively inextensible V-belt 54 are different in that the deflection characteristics of the elastomeric belt 48 are non-linear, that is as the load on this belt increases the deflection increases increasingly for each unit of additional load.

Because of this, an unblanaced force 'F' is imposed on the system by a stalled agitator 56 loads the relatively inextensible V-belt 54 so that a proportionate increment of extension occurs. At the same time, however, as this load 'F' is transferred to the flat elastomeric belt 48, the belt 48 can be said the stretch "more" thus reducing the centre to centre distance between the idler pulley arrangement 50, 52 and the agitator 56 loosening the V-belt 54 on its pulley 52 and permitting the same to slip. Since the elastomeric flat belt 48 is thereby permitted to continue to move, no burn out of it occurs and no stall condition occurs at the motor shaft 46 so that the motor of the motor-fan unit 20 is protected from a burn out condition.

It will be appreciated that the arrangement described provides such tracking in alignment of a flat belt arrangement and also prevents stall conditions at the motor or flat belt and destruction of either of them. It will also be appreciated that the invention can take many forms and that the embodiment iilustrated and described in exemplary only.

Claims (9)

1. A floor care device comprising a floor engaging tool arranged to be driven by a motor having a shaft through a belt drive and an overload arrangement including an idler pulley structure, a first belt passing around the idler pulley structure and the motor shaft, and a second belt passing around the idler pulley structure and the tool, one of the belts being relatively unstretchable compared to the other belt and the idler pulley structure being mounted so as to be movable towards and away from the motor shaft.

2. A device as claimed in Claim 1 in which the idler pulley structure is connected to a pivotally mounted arm.

3. A device as claimed in Claim 1 or 2, in which the motor is resiliently mounted on the body of the floor care device and the idler pulley structure is movably mounted on the motor.

4. A device as claimed in Claim 3 in which the idler pulley is pivotally mounted on the motor by a first bracket, which bracket is resiliently secured to the body of the floor care device.

5. A device as claimed in any preceding claim in which the first belt has a generally flat crosssection and the second belt has a generally Vshaped cross-section, the second belt being relatively unstretchable compared to the first belt.

6. A device as claimed in any one of the preceding claims in which the first belt is made of ethylene propolene diene monomer and the second belt is a fibre belt reinforced with polyester filaments.

7. A device as claimed in any preceding claim in which the diameter of the portion of the idler pulley structure around which the first belt passes is greater than the diameter of the portion of the idler pulley structure around which the second belt passes.

8. A device as claimed in any preceding claim in which the second belt passes around a portion of the tool having a diameter greater than the diameter of the portion of the idler pulley structure around which that belt passes.

9. A floor care device substantially as specifically described with reference to the accompanying drawings.