AN OUTER TUBULAR MEMBER

The present invention relates to the field of latching mechanisms, and is particularly useful in the latching of male and female tubular members so that they may be maintained in engagement or, when unlatched, axially

disengaged. The invention has particular application in the field of floor treatment machines, such as vacuum cleaners and carpet cleaners, in which a detachable connection between fluid conduits may be required.

GB-A-2114247 discloses a coupling for connecting hose or pipe ends in which a female tube is held in engagement with a male tube by means of a U-form member which has first and second inwardly projecting teeth (or bolts) which project through cut-outs in wall portions of the female tube and are seated in an annular groove in the exterior wall of the male portion. One of the projecting teeth is carried by a rocking lever arm, so that the tooth can be retracted from the groove so as to permit unclipping of the U-form member, displacement of the second tooth and thus disengagement of the male and female members.

US-B-6,832,784, US 4,220,360, EP-A-1252854 and JP-A-11032952 each disclose rocking latches for holding tubular members in engagement in which a tooth or spigot at one end of a rocking lever attached to a female tube passes through a cut-out window in the female tube and engages with a groove or depression formed in a wall portion of the male member. Thus the latch may be rocked for release of one tube from the other.

A problem with these arrangements is that axial tensile stresses (i.e. arising from disengagement forces) are taken by the tooth or spigot, which may therefore be prone to break or deform under load, which can cause failure of the latch. Otherwise, the latch may "pop", causing the latching tooth or spigot to rock out of engagement, which again is a failure of the connection. The present invention seeks to provide a latching mechanism in which provides a more secure locking of the engagement between male and female members. Other advantages will be apparent from the following description of the invention.

According to one aspect of the invention there is provided a latching mechanism for retaining an inner male member in engagement within an outer female member, the male member having an outer cylindrical surface provided with least one elongate groove or slot and the female member having at least one elongate slot provided in a cylindrical wall portion thereof, the arrangement being such that when the male and female members are engaged, the slot in the female member overlays and is aligned with the groove or slot in the male member, and wherein a pivoted latching member is provided with at least one block at a region distal to the pivot so that the latching member may rock between an unlatched position in which the male and female members may be engaged or disengaged and a latched position in which the block occupies the slot in the female member and bridges the slot or groove in the male member, thereby to prevent axial disengagement of the male and female members.

The latching mechanism may be characterised in that said elongate slot in the female member and said elongate slot or groove in the male member each have an arcuate form with a common radius of curvature (and preferably orientation) corresponding to a radial distance between the latching member pivot and the block. Thus the elongate slots/grooves in the male female members may be elongate in a direction which is circumferential with respect to the latching member pivot radius.

Said at least one block is preferably elongate in a circumferential direction with respect to the pivot radius so that in approaching the latched position the block travels along the overlaid arcuate slots, or slof an Tgrbbve, from an entry end to a distal end of each slot or groove. By provided an elongate engagement slot and an elongate block any axial separation or

disengagement forces may be spread over the length of the slot groove, rather than concentrated in at point. Said block may be configured to occupy substantially the entire volume of the overlaid slots or slot and groove when in the latched position.

Said at least one block is preferably a sliding fit in the overlaid arcuate slots or slot and groove. The fit may be an interference fit so that the latch is self- locking and reasonably fluid-tight.

One or each elongate arcuate slot or groove may extend in a generally tangential direction with respect to the cylindrical wall portion or cylindrical surface in which the slot or groove is formed.

The cylindrical outer surface of the male member is preferably formed with two of said slots or grooves. The cylindrical wall portion of the female member is similarly preferably formed with two of said wall slots. In a preferred arrangement each member has two slots or grooves each located on opposite sides of the respective member.

The latching member may have a base region which is provided with the pivot. The latching member's pivot may be oriented in a direction generally perpendicular to a member disengagement direction. Thus the pivot may have a diametrically or tangentially extending axis of rocking.

The arcuate block typically projects inwardly towards the slot/grooves.

Preferably, there are two arcuate blocks which face inwardly from opposite side regions of the latch member.

The latching member may comprise first and second generally parallel side cheeks, each respective cheek having a base region which is pivoted about a common pivot and a^istalTegion ^" provided with an associated arcuate block.

The side cheeks are connected by an inwardly extending roof portion. The roof portion may be formed with a leading edge region which, when the latch member is in the latched position, abuts a sidewall of the female member so as to prevent rocking of the member beyond the latched position. In a preferred arrangement the pivot is attached to the female member, or a fixed intermediate member, so that the latching member rocks with respect to the female member.

The female member typically comprises a tubular sleeve. The male member is a generally cylindrical spigot, and preferably a tubular member. When both members are tubular, or otherwise hollow, they may when engaged provide a fluid conduit.

The latching mechanism of the present invention finds particular application in floor treatment machines such as vacuum cleaners and carpet cleaning machines.

Thus according to a further aspect of the invention there is provided a floor treatment machine comprising a latching mechanism as claimed in any of the preceding claims in which the female member is associated with a removable reservoir and the male member is upstanding in the machine and provides a location for the placement of the reservoir in the machine, with the latching mechanism permitting locking of the reservoir in position and removal thereof from the machine as required.

The machine typically includes a vacuum suction device. The male and female members may each be tubular so that when inter-engaged a fluid conduit is formed via the male member into the reservoir for collection of liquid or detritus lifted from the floor in the reservoir.

Following is a description, by way of example only and with reference to the drawings of one way of putting the present invention into effect.

In the drawings:-

Figure 1 is two a perspective three quarter views of a carpet cleaning machine in accordance with the present invention. Figure 2 is a perspective view of the machine, partially disassembled, with a waste reservoir lifted out of the body of the machine.

Figure 3 is a perspective view from one side of the latching mechanism in accordance with the invention, with a tubular female member associated with the waste reservoir seated on a tubular upstanding spigot associated with the machine body and with the latch unlocked.

Figure 4 is a similar view to that of figure 3, but with the latch in a locked position.

Figure 5A-5E is a series of schematic views and sections.

Figure 5A is a side view with the latch locked (as per figure 4). Figure 5B is a side view with the latch unlocked.

Figure 5C is a plan view from above.

Figure 5D is a longitudinal sectional view with the latch in the locked position (per figure 5A).

Figure 5E shows the detail A from figure 5D.

Figure 6 is a longitudinal sectional view through the carpet cleaning machine.

In figure 1 a carpet cleaning machine in accordance with the invention is shown generally as 10. The machine has a generally cylindrical base portion

11. A lower region of the base portion is formed as a generally square plinth

12. The^lirrtrTis ^{^} supported by four castor wheels 13^ isposed under the four corners of the plinth.

A U-form metal handle 14 is upstanding from a rear side region of the plinth. The handle is braced by attachment to side brackets 15 which are provided on an upper rear side region of the base portion. A waste hose 6 leads from a mid-region of the rear of the base portion and sits in a spring clip 17 in an upright orientation.

An upper end of the machine is a translucent dome 18, which is detachable by means of two diametrically opposed conventional spring latches 19. The spring latches are pivotally attached at a lower end region 20 thereof to the machine sidewall and have an upper end region which latches onto a rim lip 21 of the dome.

A port 22 for air-entrained liquid and detritus lifted by a wand and flexible conduit (neither shown, but of conventional design) is formed in a front sidewall of the base portion.

In figure 2 the dome has been detached and is no longer visible. A generally cylindrical waste water reservoir 24 usually nests inside the base portion 10, but is shown having been lifted out of the base portion. The waste reservoir 24 is formed with an integral upstanding central female tubular member 25. A mid-region of the female member is formed with an annular shoulder 26 (best shown in figures 3,4 & 5). An upper end region of the female member is formed with two generally tangential, diametrically opposed arcuate slots 27.

A latching member 29 has two side cheek portions 30 on each side of the female member. A lower end region of each cheek portion has a pivot 31 by which the latching member is attached to the tubular member via respective upstanding brackets 32, which brackets are seated on the shoulder 26.

Diametrically opposed rods 33 extend from the brackets to an inner region of the reservoir sidewall. A semi-circular lift handle 34 is pivotally attached to the outer ends of the rods.

Upper end regions of the cheek portions are bridged by a roof portion 35, best shown in figure 5C. The roof portion is formed with a tail region 36 which acts as a latch handle. A leading end of the roof portion is defined by a semicircular cut-out 37. An inner lip region or block 38 of the roof portion above each side cheek projects inwardly as shown in figure 5D, so as to occupy the slots 27 when the latch member is rocked forwards and upwards against the female member (see for example figure 3). The roof portion (and lip portion/blocks thereof) is curved to match the pivot radius.

The base portion 11 of the machine is formed with an integrally moulded upstanding central tubular spigot member 40. The spigot member is formed with an annular shoulder region 41 which defines a ledge for an elastomeric annular seal 42. This ledge serves as a seat for the corresponding shoulder 26 of the waste reservoir tubular member.

An upper end region of the spigot is formed with two diametrically opposed generally tangential arcuate grooves 43.

The annular chamber 44 defined within the base portion sidewalls and the spigot serves as a reservoir for cleaning liquid, which is fed to the floor/carpet surface during cleaning.

When the waste reservoir 24 is placed in the base portion 11 the spigot member 40 engages with the female member 25. Both female member and spigot member are slightly frusto-conical (tapered) in configuration so as to aid in locating and mating the two. The waste reservoir 24 is shown in position in the machine 10 in figure 6. The machine includes an electric vacuum suction drive/fan unit 50, a chamber 44 for cleaning liquid and a waste liquid collection reservoir 45. The port 22 admits air-entrained waste into the machine. An L-form pipe 46 vents the waste upwards against a dome inside surface 47. The waste then falls into the reservoir chamber 45, and may thereafter be emptied using the hose 17, which may be undipped from the clip 17 and directed downwards to a drain (not shown). The suction unit 50 maintains a Tow pressure (as indicated itT) in the spigot member, dome and waste reservoir.

As shown in figure 5D, when the spigot and female member are mated, the latch member may then be pivoted upwards and forwards to lock the spigot and female member against axial detachment. The lip portion/blocks 38 of the latch member extend through the slots 27 and enter the spigot grooves 43 along a direction which is circumferential with respect to the latch member pivot radius. Thus the blocks bridge the interface between the spigot and female member and lock them in engagement. The blocks are preferably a sliding interference/friction fit in the grooves/slots.

The latch may then be released to permit detachment of the waste reservoir from the machine for emptying thereof, and/or refilling of cleaning liquid into the annular chamber 44 of the base portion 11 of the machine.

While the latching mechanism has been described in the context of a floor treatment machine, it has more general application in the connection of male and female members, in particular tubular members.