MXPA00005643A - A clutch mechanism - Google Patents

Abstract

The invention provides a clutch mechanism (200) having a driven pulley (32) and a drive pulley (34) to which a load is applied, the clutch mechanism (200) having an engaged position in which torque applied in use to the driven pulley (32) is transmitted to the drive pulley (34), and a disengaged position in which torque applied in use to the driven pulley (32) is not transmitted to the drive pulley (34), wherein the clutch mechanism (200) also has override means (238, 242) by which at least a proportion of the torque applied to the driven pulley (32) is absorbed when the load applied to the drive pulley (34) exceeds a predetermined value. The invention also provides a clutch mechanism (200) having a driven pulley (32) and a drive pulley (34) to which a load is applied, the clutch mechanism (200) having an engaged position in which the torque applied in use to the driven pulley (32) is transmitted to the drive pulley (34), and override means whereby at least a proportion of the torque applied in use to the driven pulley (32) is absorbed when the load applied to the drive pulley (34) exceeds a predetermined value, the override means comprising a pair of detent plates (238, 242), the detent plates being pressed together so as to transmit torque therebetween in the engaged position, and the detent plates (238, 242) being rotatable with respect to one another when override occurs, and at least one ball-bearing (248) being held captive between the detent plates (238, 242), the detent plates (238, 242) being adapted so as to retain the at least one ball-bearing (248) within a groove in each detent plate, wherein each groove is continuous about the axis of rotation of the detent plates.

Description

A MECHANISM OF EMBRAGU E The invention relates to a clutch mechanism. Particularly, but not exclusively, the invention relates to a clutch mechanism for use in conjunction with the brush bar of a vacuum cleaner and the operation of the same. Vertical vacuum cleaners have dirty air inlets directed downwards installed in the vacuum head through which the dirty air is drawn into the vacuum cleaner. In the vast majority of cases, a brush bar is rotatably installed in the mouth of the dirty air inlet so that the fibers of a carpet are swirled over which the vacuum cleaner passes to release dirt and dust trapped in the carpet. The brush bar is normally rotated by the motor of the vacuum cleaner by means of a transmission belt. Vertical vacuum cleaners are commonly convertible into vacuum cleaners which can be used as a cylinder vacuum cleaner for floor cleaning. In this mode of operation, the main part of the cleaner, including the cleaning head, remains frequently immobile for a period of time with the engine running while the dirty air is drawn into the vacuum cleaner through a hose or rod. If the brushing bar is allowed to continue brushing against the carpet during this time, the carpet may wear out unnecessarily. Many vacuum cleaners incorporate devices to automatically lift the suction head and brush bar from the carpet when the vacuum cleaner is placed in cylinder mode, but the rotation of the brush bar does not stop normally due to the lifting of the head Vacuum cleaner prevents unnecessary brushing of the carpet. A clutch mechanism has been proposed in which the drive belt used to drive the brush bar is deflected on a transmission pulley to disengage the drive when the vacuum cleaner is placed in the cylinder operation mode, but this type of mechanism is bulky, expensive to produce and not reliable. Another difficulty with vertical vacuum aspirators is that, from time to time, the brush bar becomes jammed. When this occurs, the motor may overheat easily and / or the drive belt may be damaged. Some machines are equipped with devices to automatically stop the motor when it overheats, but this is not always enough to warn the user of the cause of interruption and when the motor cools down, the vacuum is turned on again but the problem remains. In addition, there is always a risk, with machines of this type, that foreign objects such as children's fingers may be inserted into the dirty air inlet and serious injury may result from a rotating brush bar. It is an object of the present invention to provide a clutch mechanism, particularly a clutch mechanism suitable for use with a rotary brush bar of a vacuum cleaner, which is compact and reliable when used to disengage the drive from a vacuum cleaner. the brush bar. Another object is to provide a clutch mechanism which reduces the risk of engine overheating or mechanical failure in the event that the torque required to overturn the brush bar exceeds a predetermined level. A further object is to provide an embossing mechanism that urges the user of a vacuum aspirator to remove the cause of the problem when the brush bar is locked. The invention provides a clutch mechanism as set forth in claim 1. The supply of the limiting means, in addition to the clutch and disengaged positions, provides a clutch mechanism capable of allowing the brush bar to be operated in the engaged position, of disengaging the drive of the brush bar when cleaning is carried out on the floor, and also of allowing the motor to continue on without overheating or destroying the transmission belt (or belts) if the torque required to turn the brush bar exceeds a predetermined level. A vacuum cleaner in which the clutch mechanism is adjusted is thus safer to operate than known vacuum cleaners and is less prone to damage or failures that require maintenance or to adjust spare parts. Therefore, the vacuum cleaner is cheaper to start up and is more user-friendly. A preferred feature of the invention is set forth in claim 4. The provision of a mechanism in which both transmission belts remain transported by their respective pulleys in the same axial position means that the clutch mechanism can be placed in the disengaged position. no need for bulky, unreliable means to transfer one or more drive belts to a drive pulley. Removing the need for axial movement of any of the pulleys leads to less deterioration in the components involved and also reduces the likelihood of malfunction. A further preferred feature of the invention is set forth in claim 5. The provision of a mechanism which produces a limiting signal when limitation occurs attracts the attention of the user of a vacuum cleaner in which the mechanism conforms to the fact that the torque required to flip the brush bar exceeds a predetermined value and the need for the cause of the problem to be removed. The limitation signal is given every time the brush bar is locked or delayed and is not activated by the operating temperature of the motor. Therefore, the user of the vacuum cleaner is urged to remove the cause of the problem before restarting the cleaning, which is not always the case with vacuum cleaners where the motor is interrupted when its operating temperature exceeds a predetermined value when The brush bar is locked. The invention discourages the user from continuing to use the machine under abnormal or strained conditions.

An additional advantage is that, when the limiting signal is audible, an audible warning is given immediately after a foreign object such as a child's fingers is inserted into the dirty air inlet thus minimizing any delay between an accident occurring and his discovery. The invention also provides a clutch mechanism as set forth in claim 1. The additional advantageous and preferable features of the invention are set forth in the subclaims. A mode of the invention will be fully described and explained with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of the vacuum head of a vacuum cleaner which illustrates the relative positions of an engine, a bar of brush and a clutch mechanism according to the invention; Figures 2 and 2A are side and front views of a clutch mechanism according to the invention which omits the transmission belts for reasons of clarity: Figure 3 is an exploded isometric view of the components of the mechanism of the figures. 2 and 2A; Figure 4 is a cross-sectional view of the mechanism of the Figures 2 and 2A shown in the normal or clutch operating position including the transmission belts carried by the pulleys; Figure 5A is a cross-sectional view similar to Figure 4 but illustrating the static and rotating parts of the mechanism, again in the engaged position; Fig. 5B is a cross-sectional view similar to Fig. 5A but showing the mechanism in the disengaged position; and Figure 5C is a cross-sectional view similar to Figure 5A but which shows the means of limitation in operation. Fig. 1 illustrates schematically the vacuum head 1 0 of a vacuum cleaner 1 00. The head of the vacuum cleaner 10 is mounted in a radial fashion on a motor housing 12 located at the lower end of a main body 14 in the that the dust separating apparatus (not shown), in the form of a dust bag, cyclonic separator or other filter, is housed. A pair of wheels 1 6 are also mounted on the motor housing 1 2, from which the vacuum head 10 extends in a forward direction. The vacuum head 1 0 has a dirty air inlet 18 located at its front end and facing downwards so that, in use, the dirty air inlet 1 8 remains on the surface 20 to be cleaned, usually a floor or carpet. A brush bar 22 is rotatably mounted in a known manner by means of bearings (not shown) so that the brush bar 22 extends through substantially the full width of the dirty air inlet 1 8. The brush bar 22 protrudes slightly out of the dirty air intake 1 8 so as to agitate the fibers of a carpet being cleaned and in a manner that improves the cleaning process.

A motor 24 is housed within the motor housing 1 2. Normally, the motor 24 would be used to drive the brush bar 22, either directly or by means of a gear mechanism. Prior art machines are known to include clutch mechanisms that have transmission pulleys to receive one of the transmission belts and mechanisms to transfer the relevant belt to the transmission pulley as previously described, but these mechanisms are not Reliable In the embodiment shown, the clutch mechanism 200 according to the invention is located between the motor 24 and the brush bar 22 and the transmission belts 26, 28 are installed so that the torque is transferred from the motor 24. to the clutch mechanism 200 and from the clutch mechanism 200 to the brush bar 22 respectively. The motor 24 can be any suitable motor for use in domestic vacuum cleaners. It must be able to receive a transmission belt 26 and therefore transport, a driving pulley a30 to receive the drive belt 26. The drive belt could be similarly transported directly on the motor shaft. The transmission belt 26 is also transported by a driven pulley 32 which forms part of the clutch mechanism 200 (to be described more fully below). The clutch mechanism 200 also has a driving pulley 34 which carries the transmission belt 28, which is also carried by a pulley 36 on the brush bar 22. The transmission belts 26, 28 are preferably transmission belts. reinforced, high strength, which have an expected life of 10 years under normal operating conditions. They may be grooved, or toothed but preferably flat belts. The relative diameters of the pulleys 30, 32, 34, 26 are designed to reduce the rotating speed of the motor (commonly 30-40k rpm) at a suitable rotational speed for the brush bar 22. A suitable rotary speed for a bar brush 22 is typically 3.5-5k rpm. The brush bar 22 may be of any known design, preferably having an array of flared bristles at the edges thereof to facilitate edge-to-edge cleaning. The precise characteristics and dimensions of the brush bar 22, the vacuum head 1 0 and the motor 24 are not significant for the present invention and will not be described further here. The specific characteristics of the clutch mechanism 200 will now be described in detail with reference to Figs. 2, 2A, 3 and 4. Looking primarily at Figs. 2 and 2A, it can be seen that the clutch mechanism 200 is a separate unit having a main housing 202 and an actuator 204. The actuator 204 is connected to the main housing 202 so that it is rotatable with respect thereto, as will be described below. An actuator tag 206 extends outwardly from the actuator 204 at a circumferential location, and a hand actuator grip portion 208 extends outwardly from the actuator 204 at another circumferential location. The functions of these parts will be fully described below. The main housing 202 incorporates the molded projections 21 0 having through holes for receiving screws or bolts by means of which the bracket mechanism 200 can be mounted on a suitable part of the vacuum cleaner vacuum cleaner head, or at any Another suitable position for your operation. The main housing 202 also incorporates the openings 21 2, 214 positioned and sized so as to allow the transmission belts 26, 28 to pass through the main body 202 towards the pulleys 32, 34. The components of the clutch mechanism 200 are shown in an exploded view in Figure 3. The clutch mechanism 200 has a base cover 220 which is formed essentially like an annular disc 220a having an annular flange 200b around the outer circumference thereof. Three eyelets 220c are spaced around the circumference of the annular disc 220a and incorporate through holes to receive screws or bolts to secure the base cover 220 to the main housing 202. A right cylindrical wall 220d is located around the inner circumference of the cover of base 220 and right wall 220d has a flange extending inwards 220e around its base. A first cylindrical bearing 222 is dimensioned to fit without play in the recess formed by the right wall 220d and the inwardly extending flange 220e acts as a stop to prevent unimpeded axial movement of the first cylindrical bearing 222 through said recess.

A second cylindrical bearing 224 in the form of a needle bearing receives a shaft 226 and freely extends therein. The shaft 226 has an annular groove 226a for receiving a circular spring 228 therein. The second cylindrical bearing 224 is dimensioned so that it fits inside the first cylindrical bearing 222 leaving a small annular space between the inner wall of the first cylindrical bearing 222 and the outer wall of the second cylindrical bearing 224. The driven pulley 32 consists of a surface of generally cylindrical outer pulley 32a adapted to receive the drive belt 26. The reinforcement projections are spaced around the inner circumference of the cylindrical surface 32a. An axially extending circumferential wall 32c is dimensioned to fit without play in the annular space defined between the first cylindrical bearing 222 and the second cylindrical bearing 224. In this manner, the driven pulley 32 bears between the indium cylindrical bearings 222.224. The driven pulley 32 carries a plurality of axially extending pins 32d which are generally rectangular in shape and extend axially out of the driven pulley 32 on the remote side of the base cover 220. In the illustrated embodiment, the pulley 32 They show six spikes 32d spaced equidistantly. A plurality of friction discs 230 and a corresponding number of clutch discs 232 are located within the circumference defined by the pins 32d. In the embodiment shown, two friction discs 230 and two clutch discs 232 are shown, although more friction discs and clutch discs may be provided if desired. The supply of only a single friction disc and a single clutch disc is also possible. The clutch discs 232 are placed between the friction discs 230 so that the friction discs 230 altee with the clutch discs 232. Each friction disc 230 has a plurality of pins 230a that extend outwardly from the outer circumference of the same. The pins 230a are dimen- sioned so as to project into the spaces between the pins 32d of the driven pulley 32. In this way, when the driven pulley 32 rotates, the friction discs 230 must rotate with the driven pulley 32. inner circumference of each friction disk 230 is circular. Each clutch disk 232 has a circular outer circumference sized to sit within the pins 32d but is provided with a plurality of inwardly projecting pins 232a projecting inwardly beyond the inte circumference of the friction discs. 230. The thickness of the friction discs 230 and the clutch discs 232 is such that, when all the friction discs 230 and the clutch discs 232 are placed against each other, the pins 32d of the driven pulley 32 extend at least as far as the friction disk 230 which is furthest from the driven pulley 32. A support member 234 is generally in the form of a dish under construction. The base of the support member 234, that is, the face facing the base cover 220, is generally cylindrical and has a plurality of outwardly extending pins 234a which are installed and sized to project into the spaces between the pins 232a around the inner circumference of each clutch disk 232. In this way, the support member 234 is rotatable with the clutch discs 232. A circumferential ridge projects outwardly from the support member 234 for the purpose of allowing an axial force to be applied to the clutch disc 232 furthest from the base cover 220. A central opening 234c extends through the support member to allow the shaft 226 to pass therethrough. The support member 234 snaps into the shaft 226 so that the support member 234 rotates with the shaft 226. On the side of the remote support member 234 of the spikes 234a are additional spikes 234d which extend parallel to the shaft 226 and away from the base cover 220. These additional pins 234d are shown as being less in number than the pins 234a, although the sizes and relative spacings are immaterial. A compression spring 236 sits in the disc-shaped interior of the support member 234. The compression spring 236 is supported against a first mechanical brake disc 238 which is mounted on the shaft 226 by means of a bearing 240. The first mechanical brake disc has outwardly projecting pins 238a which are spaced apart and dimensioned to project into the spaces between the pegs 234d of the support member 234. Accordingly, the first mechanical brake disc 238 is rotatable. with the support member 234. The first mechanical brake disc 238 is maintained at an l distance relative to the support member 234 by the compression spring 236 so that, if sufficient force were to be applied to the first mechanical brake disc 238 , the first mechanical brake disc 238 could move lly towards the support member 234. A second mechanical brake disc 242 is mounted on the shaft 226 by means of a cushion 244. The second mechanical brake disc 242 also has outwardly projecting pins 242a, but these do not project into the spaces between the pins 234d of the support member 234. Between the first and second arrest discs, 238 , 242 a bearing cage disc 246 is interposed. The bearing cage disc 246 is also mounted on the shaft 226 and is freely rotatable about the shaft 226. The bearing cage disc 246 has a plurality of through holes 246a (three are shown in this embodiment) in which three ball bearings 248 are held captive. Each mechanical brake disk 238, 242 has a plurality of inclined slots 242b which are formed such that, when the first and second discs of mechanical brake 238,242 rotate with respect to each other, the relative rotation of the ball bearings 248 forces the mechanical brake discs 238,242 apart thereby compressing the compression spring 236. The slots 242b also include flanges and recesses which also allow the mechanical brake discs 238,242 to be pressed together under the action of the compression spring 236. The shape of the slots 242b ensures that the ball bearings 248 are pressed inwardly. of the relatively fast recess thus causing an audible sound each time a ball bearing 248 falls into a recess. The mechanical brake discs 238, 242 also carry small ramp-type projections 242c on which the bearing cage disc 246 is mounted when there is relative g between the mechanical brake discs 238, 242. This ensures that the disc bearing cage 246 remains in a position relative to the ball bearings which discourage them from rolling out of the through holes 246a, ie, in a substantially equidistant position from the mechanical brake discs 238,242. The conductive pulley 34 includes on its side facing a base cover 220 a plurality of pins 34a which are designed to project into the spaces between the pins 242a in the second mechanical brake disk 242. Therefore, in FIG. both, the driving pulley 34 is rotary with the second mechanical brake disc 242. The driving pulley 34 includes a cylindrical surface 34b for receiving the transmission belt 28 leading to the brush bar 22. A flange extends to outside 34c retains the transmission belt 28 on the cylindrical surface 34b. The driving pulley 34 is mounted on the shaft 226 by means of a bearing 250.

A third indium cylindrical bearing 252 is installed on the shaft 226 adjacent to the drive pulley 34. The third cylindrical bearing 252 is mounted on the shaft 226 by means of a bushing 253 so as to support the shaft but also to allow movement axial between the third indium cylindrical bearing and the shaft 226. A fourth cylindrical bearing 254, which is mounted on the shaft 226 near the circular spring 228, also supports the shaft 226 although a small gap of approximately 1.5mm is left between the circular spring 228 and the face of the fourth cylindrical bearing 254 adjacent to the circular spring 228. The main housing 202 is designed to cover and include the inner components of the clutch mechanism 200. The main housing 202 has a cylindrical portion 202a and dimensioned of way including the driven pulley 32. Three protrusions 202b which incorporate through holes are spaced around the indian cylindrical portion 202a and cooperate with the projections 220c on the base cover 220. In this way, the screws or bolts can be used to secure the main housing 202 to the base cover 220. The main housing 202 also has a central portion 202c dimensioned and designed to include the friction and clutch discs 230,232, the support member 234, the compression spring 236, the mechanical brake discs 238,242, the bearing cage disc 246 and the ball bearings 248, and also the pulley The installation of the components allows a good hermetic seal to stay inside the clutch mechanism, particularly in the area of the base of the drive pulley 34, which prevents dirt and dust from entering the clutch mechanism. vulnerable parts of the mechanism. The main housing 202 also has a terminal portion 202d which projects into the interior of the actuator 204. The end portion 202d is dimensioned to accept and accommodate the third and fourth cylindrical bearings 252 and 254 and also the end of the remote shaft 226a of the base cover 220. The end portion 202d incorporates a support 202e against which the fourth cylindrical bearing 254 is spliced in order to avoid unimpeded axial movement. The end portion 202d also incorporates an outwardly extending flange 202f which includes a recess for receiving one end of a torsion spring 256. The other end of the torsion spring 256 is retained by the actuator 204. The main housing 202 and the actuator 204 also include cam surfaces 258. By means of these cam surfaces 258, the position of the actuator 204 relative to the housing 202 is altered when the actuator 206 is rotated about the shaft 226. As previously mentioned , the actuator 204 includes an actuator tag 206 and also an actuator assimilation portion 208 so that the actuator 204 can be rotated with respect to the housing 202 either manually or automatically by the rotation of the vacuum cleaner vacuum head with with respect to the main body and / or motor housing. Finally, an opening in the upper part of the actuator 204 is closed by means of a cover 260. Figure 4 shows a clutch mechanism 200 in its assembled form. It will be appreciated that the main housing 202 is fixedly connected to the base cover 220 by screws or bolts. The torsion spring 256 is acting so as to press the actuator 204 towards the housing 202. The shaft 226 is pressed to the left by means of the spring 236 and the clutch discs 232 are therefore pressed firmly against the friction discs. 230. This pressure contact means that any rotation of the friction discs 230 causes the clutch discs 232 to rotate. In addition, the ball bearings 248 are also pressed by the compression spring 236 into the recess 242b in the discs 248. mechanical brake 238, 242 and therefore any rotation of the first mechanical brake disk 238 causes the second mechanical brake disk 242 to rotate. This is then the normal driving position of the clutch mechanism 200. When the driven pulley 232 is g With the transmission belt 26, the friction discs 230 are rotated and, due to the pressing force between the friction discs 230 and the clutch discs 232, the clutch discs 232 also rotate. This causes the support member 234 to rotate and therefore also the shaft 226 and the first mechanical brake disc 238. The pressing action of the compression spring 236 retains the ball bearing 248 within the recess 242b in the second disc. of mechanical brake 242 which also rotates. This causes the rotation of the driving pulley 34 and the torque is transmitted by means of the belt 28 to the brush bar 22. Figure 5A in which the shaded parts are the radiating parts, illustrates this normal driving position. of the clutch mechanism 200. When the vacuum cleaner 1 00 is to be used for cleaning on the floor, the handle of the vacuum cleaner will be brought in the vertical position. The relative movement between the main body 14 and the vacuum head 1 0 can be used to activate the label of the actuator 206 automatically and cause the actuator 204 g to move with respect to the main housing 202. The rotation of the actuator 204 with respect to the main housing 202 of the clutch mechanism 200 causes the interaction of the cam surfaces 258. The cam surfaces 258 cause the actuator 204 to lift slightly with respect to the main housing 202. This brings the clutch mechanism 200 into the disengaged position shown. in Figure 5B. As can be seen, the lifting of the actuator 204 causes the fourth cylindrical bearing 254 to lift the shaft 226 when it is joined against the circular spring 228. In this way, the complete shaft 226 is lifted by a distance of not more than 1.5mm. The shaft 226 slides in the bearing 253 in which the third indium cylindrical bearing 252 is mounted. It also slides in the bearing 250 transporting the driving pulley 34 and in the bearings 240,244 transporting the first and second mechanical brake discs 238, 242. respectively. However, the support member 234 is raised with the shaft 226 against the action of the spring 236 so as to release the pressure force acting between the friction discs 230 and the clutch plates 232. Therefore, the Brake discs 232 are not pressed further against the friction discs 230 and consequently the torque is not transmitted between them. In this position, the driven pulley 32 is still driven by the transmission belt 26. Although the friction discs 230 are rotated with the driven pulley 32, the clutch plates 232 are not driven by the friction discs 230. both, the support member 234 remains static, together with the shaft 226, the mechanical brake discs 238,242 and the drive pulley 34. In this position, the torque imparted to the driven pulley 32 by the drive belt 26 does not it is transmitted to the driving pulley 34 by the belt 28. FIG. 5B illustrates the unbalanced position, again with the rotating parts shown shaded. The actuator hold portion 208 is provided so that the user of the vacuum cleaner 1 00 places the clutch mechanism 200 in the disengaged position at any time. This device is useful in a number of situations, particularly when the vacuum cleaner is being used on a floor without carpet and the brush bar is not required. The clutch mechanism 200 also has a limiting means in the form of the first and second mechanical brake discs 238, 242. It sometimes happens that the brush bar 22 is locked and therefore the torque required to turn the bar of brush increases drastically. An appreciable increase in the torque required to turn the brush bar can also be found if the vacuum cleaner is used in a carpet having a very large pile. When the torque is increased beyond a predetermined level, there may be a serious risk that the engine 24 will overheat or that one of the transmission belts 26, 28 will deteriorate. If the brush bar 22 is locked or the torque required to overturn is too large, the drive pulley 34 should not be rotated. In this situation, there is a forced relative motion between the first and second mechanical brake discs 238,242. The ball bearings 248 mounted around the slots 242b in the mechanical brake discs 238,242 while the rest are held captive by the bearing cage disc 246 which is prevented from being twisted with respect to the mechanical brake discs by means of the Ramp type projections 242c. This relative rotation is allowed by the forced pressure of the first mechanical brake disc 238 against the action of the compression spring 236. The compression of the spring 236 also increases the force applied by means of the support member 234 to the friction discs 230 and the clutch discs 232 which reduces the risk of slippage occurring between them immediately before or during limitation. The action of the compression spring 236 presses the ball bearings 248 back into the recess in the mechanical brake discs 238,242 at each opportunity and the speed of the relative weight is such that the ball bearings 248 produce noisy noise during any limitation. The audible signal alerts the user of the vacuum cleaner 1 00 of the fact that the brush bar 22 is locked and requires cleaning before restarting the normal use of the vacuum cleaner 1 00, or the fact that the brush bar is delay, perhaps due to the length of the hair of the carpet. The limiting operation of the clutch mechanism 200 is shown in Figure 5C with the rotating parts shown shaded. The advantages of the braking mechanism described above will be clear to an experienced reader. In particular, the mechanism is lightweight and compact with a construction which will not be prone to failure. The moving components are housed within a protective housing and, under normal operating conditions, there will be only minimal movement in the axial direction of only a few components because there is no need to transfer the drive belts from one pulley to another. as in the prior art. In case of failure, the clutch mechanism can be removed from the vacuum cleaner as a single unit and may require either service or replacement if desired. The provision of a limiting signal, which is preferably audible and uncomfortably noisy in the normal operating environment of a home, encourages the user to ensure that the cause of the limitation is removed before continuing to use the vacuum cleaner, very often merely when removing material which has become entangled around the brush bar causing it to lock. This results in a vacuum cleaner that is being operated under appropriate working conditions a high percentage of time and extends the life of the cleaner. It also results in better customer satisfaction and lower running costs due to the fact that less maintenance and fewer spare parts are required. For illustrative purposes only, a clutch mechanism as described above can be adjusted in the vacuum head of a vacuum cleaner having a 600W motor. The power required to flip the brush bar under normal operating conditions would be about 1 5W, or perhaps less. If the brush bar is locked or delayed so that the power required to apply enough torque to turn it up increases to about 45W, the override mechanism would operate causing the ball bearings to extend around the recesses and provide the user with a signal. The power required to drive the override means is only 1 5W and therefore the mechanism will only restart the actuation of the brush bar when the power required to do so is less than 1 5W. The characteristics of the mechanism can be adjusted by altering the characteristics of various components, especially the compression spring.

Claims (9)

REIVIN DICACIONES

1 . A clutch mechanism having a driven pulley and a driving pulley to which a load is applied, the clutch mechanism having a clutch position in which the torque applied in use to the driven pulley is transmitted to the driving pulley , and a disengaged position in which the torque applied in use to the driven pulley is not transmitted to the driving pulley, wherein the clutch mechanism also has a limiting means by means of which at least a proportion of the moment of The torsion applied to the driven pulley is absorbed when the load applied to the driving pulley exceeds a predetermined value, the limiting means being separated and axially displaced from the driving pulley and the driven pulley.

2. A clutch mechanism according to claim 1, characterized in that the limiting means is effective when the clutch mechanism is in the engaged position.

3. A clutch mechanism according to claim 1 or 2, characterized in that the driving pulley is connected to a brush bar of a vacuum cleaner. A clutch mechanism according to any of the preceding claims, characterized in that each pulley is adapted to carry a belt and because, in use, each belt remains transported by the respective pulley, and the axial position of each pulley and belt remains the same both in the clutch position as in the disengaged position. 5. A clutch mechanism according to any of the preceding claims, characterized in that the limiting means is adapted in order to provide a limiting signal when limitation occurs. 6. A clutch mechanism according to any of the preceding claims, characterized in that the limiting means comprises a pair of mechanical brake discs, the mechanical brake discs being pressed together to transmit the torque between them in the engaged position. , and the mechanical brake discs being rotatable with respect to each other when limitation occurs. A clutch mechanism according to claim 6, characterized in that the mechanical brake discs are pressed together to transmit the torque between them in the engaged position. A clutch mechanism according to claim 7, characterized in that the mechanical brake discs are pressed together by means of a compression spring. 9. A clutch mechanism according to any of claims 6 to 8, characterized in that at least one ball bearing is held captive between the mechanical brake discs and the mechanical brake discs are adapted to retain the ball bearings inside. of a slot in each mechanical brake disc. 1 0. A clutch mechanism according to the claim 9, characterized in that at least one of the slots includes recesses in which the rolling balls are pressed in order to generate an audible sound when the limitation occurs. eleven . A clutch mechanism according to claim 9 or 10, characterized in that the ball bearings are held captive by means of a bearing cage disc placed between the mechanical brake discs. 12. A clutch mechanism according to the claim 10, characterized in that the mechanical brake discs include ramp-type projections to keep the bearing cage disc substantially equidistant from each mechanical brake disk during limitation. 1 3. A clutch mechanism that has a driven pulley and a driving pulley to which a load is applied, the clutch mechanism having a clutch position in which the torque applied in use to the pulley conductive is transmitted to the driving pulley, and a limiting means by which at least a proportion of the torque applied to the driven pulley is absorbed when the load exceeds a predetermined value, the limiting means being separated and axially displaced from the driving pulley and the driven pulley and comprising a pair of mechanical brake discs, the mechanical brake discs being pressed together to transmit the torque between them in the engaged position, and the mechanical brake disks being rotatable with respect to each other when the limitation occurs, and at least one ball bearing between the mechanical brake disks being captive, the mechanical brake disks being adapted to retain the at least one ball bearing Within a slot in each mechanical brake disc, wherein each slot is continuous around the axis of rotation of the mechanical brake discs. 1

4. A clutch mechanism according to claim 13, characterized in that at least one of the slots includes recesses in which the ball bearings are pressed in order to generate an audible sound when limitation occurs. 1

5. A clutch mechanism according to any of claims 13 or 14, characterized in that the ball bearings are held captive by means of a bearing cage disc placed between the mechanical brake discs. A clutch mechanism according to claim 15, characterized in that the mechanical brake discs include ramp-type projections for keeping the bearing cage disc substantially equidistant from each mechanical brake disk during limitation. 17. A clutch mechanism according to any of claims 13 to 16, characterized in that the clutch mechanism also has a disengaged position in which the torque applied in use to the driven pulley is not transmitted to the drive pulley. . A clutch mechanism according to any of claims 1 to 1 2 and 1 7, characterized in that the mechanism comprises at least one friction disk and at least one clutch disk, the friction and clutch plates being pressed together in order to to transmit the torque between them in the engaged position, and the friction and clutch plates being rotatable independently in the disengaged position. 19. A clutch mechanism according to the claim 18, characterized in that the friction and clutch discs are pressed together in order to transmit the torque between them in the limiting position. 20. A clutch mechanism according to claim 18 or 19, characterized in that the driving pulley, the driven pulley, the friction discs and the clutch discs are all mounted on a shaft and the axial movement of the shaft causes the friction discs and clutch either be pressed together or released, according to the position of the clutch mechanism. twenty-one . A clutch mechanism according to claim 20, characterized in that the clutch discs and the friction discs are pressed together under the action of a compression spring in the clutch and limiting positions. 22. An embossing mechanism according to claim 20 or 21, characterized in that the mechanism comprises a housing and an actuator which is rotatable with respect to the housing. 23. A clutch mechanism according to claim 22, characterized in that the rotation of an actuator with respect to the housing causes axial movement of the shaft. 24. A clutch mechanism according to claim 22 or 23, characterized in that the cam surfaces are provided between the actuator and the housing so that the rotation of the actuator with respect to the housing causes a variation in the axial position of the actuator with respect to the actuator. To the accommodation. 25. A clutch mechanism as described above with reference to the accompanying drawings. 2

6. A vacuum aspirator incorporating an embedment mechanism according to any of the preceding claims.