GB2471115A

GB2471115A - A floor tool

Info

Publication number: GB2471115A
Application number: GB0910456A
Authority: GB
Inventors: Giles Ashbee
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2009-06-17
Filing date: 2009-06-17
Publication date: 2010-12-22
Anticipated expiration: 2029-06-17
Also published as: GB2471115B; GB0910456D0

Abstract

A floor tool 10 for a surface treating appliance comprises a main body (12, fig 1) connected to a conduit (14, fig 1). The conduit (14, fig 1) comprises a head 54 pivotably connected to the main body 12 for movement relative thereto, and a neck 56 connected to the head 54. The head 54 comprises a first port 64 and a second port 64 though each of which fluid is conveyed into the conduit (14, fig 1) from the main body (12, fig 1. To reduce turbulence within the head 54, the head 54 comprises guide surfaces 66 for directing fluid entering the head 54 through each port 64 towards the neck 56. The first port 64 and the second port 64 may be located on opposite sides of the head 54.

Description

A Floor Tool The present invention relates to a floor tool for a surface treating appliance. In its preferred embodiment, the present invention relates to a floor tool for a vacuum cleaning appliance.

Vacuum cleaners are generally supplied with a range of tools for dealing with specific types of cleaning. The tools include a floor tool for general on-the-floor cleaning. The floor tool comprises a main body which engages with a floor surface. The main body has a lower surface comprising a suction opening through which, in use, dirt and dust is drawn into the floor tool from the floor surface.

It is useful for the main body to be pivotably connected to the remainder of the floor tool so that the suction opening can remain in close proximity to the floor surface as the floor tool is manoeuvred over the floor surface.

In a first aspect the present invention provides a floor tool for a surface treating appliance, comprising a main body connected to a conduit, the conduit comprising a front section pivotably connected to the main body for movement relative thereto about a first axis and a rear section connected to the front section for movement relative thereto about a second axis angled to the first axis, wherein the front section comprises at least one port though which fluid is conveyed into the conduit from the main body, said first axis passing through said at least one port.

To enable the main body to be widely manoeuvrable over a floor surface, the conduit comprises a front section and a rear section. The front section is pivotably connected to the main body for movement about a first axis to allow the rear section of the conduit to be raised and lowered relative to the main body, which allows the main body to be manoeuvred easily beneath furniture, and into gaps between furniture and walls, for example, as required. The range of articulation of the sections of the conduit about the first and second axes preferably enables the main body to be oriented both substantially

I

perpendicular to a wand used to manoeuvre the floor tool over a floor surface, and substantially parallel to the wand.

The front section of the conduit is pivotable relative to the main body about an angle which is preferably at least 60°, more preferably of at least 80°. In a preferred embodiment, the front section of the conduit is pivotable relative to the main body about an angle in the range from 90 to 180° as the front section of the conduit moves from a ftilly lowered position. A stop member may be provided on one of the conduit and the main body to limit the angular movement of the conduit relative to the main body through contact between the stop member and the other one of the conduit and the main body.

The rear section is connected to the front section for movement relative thereto about a second axis which is angled to the first axis. This allows the rear section to be angled relative to the front section to assist in the pushing, or pulling, of the main body over the floor surface in a variety of orientations of the main body relative to, for example, a wand connected to the rear section of the conduit. The rear section is preferably pivotably connected to the front section for movement relative thereto about the second axis. The rear section of the conduit is pivotable relative to the front section of the conduit about an angle which is preferably at least 120°, more preferably of at least 150°. Stop members may again be provided, this time on one of the front section and the rear section, to limit the angular movement of the rear section relative to the front section through contact between the one of the stop members and the other one of the front section and the rear section.

The rear section of the conduit preferably comprises a substantially circular fluid inlet which is rotatably connected to a conformingly shaped fluid outlet of the front section of the conduit so that the second axis passes centrally through, and is substantially orthogonal to, the fluid inlet of the rear section and the fluid outlet of the front section.

Consequently, as the fluid inlet of the rear section rotates relative to the fluid outlet of the front section, the rear section of the conduit inclines relative to the front section.

The fluid outlet of the front section is preferably substantially orthogonal to the at least one port, and so the second axis is preferably substantially orthogonal to the first axis.

The front section comprises at least one port though which fluid is conveyed into the conduit from the main body. The first axis preferably passes through, more preferably through the centre of, the at least one port. This can enable a relatively simple seal to be provided between the main body and the conduit to inhibit fluid loss from therebetween to the external environment regardless of the position of the conduit relative to the main body.

The front section of the conduit preferably comprises a head pivotably connected to the main body and a neck connected to the head, with said at least one port being located on the head. The at least one port preferably comprises a first port and a second port, which may be conveniently located on opposite sides of the head to facilitate sealing between the conduit and the main body. Therefore, in a second aspect the present invention provides a floor tool for a surface treating appliance, comprising a main body connected to a conduit, the conduit comprising a head pivotably connected to the main body for movement relative thereto, and a neck connected to the head, the head comprising a first port and a second port though each of which fluid is conveyed into the conduit from the main body, with the first port and the second port being located on opposite sides of the head, and with the pivot axis preferably passing through the first port and the second port.

To facilitate sealing between the main body and the conduit, each port is preferably substantially circular, and the ports are preferably concentric. Each port is preferably located in a plane extending substantially parallel to the second axis irrespective of the position of the conduit relative to the main body. In a preferred embodiment the head is substantially cylindrical, with the first and second ports being located at opposing ends of the cylindrical head. The head has a longitudinal axis to which the first and second ports are preferably substantially orthogonal. This longitudinal axis and the first axis are preferably co-linear.

The neck is preferably connected to the head substantially midway between the first and second ports, and preferably extends away from the head in a direction which is substantially orthogonal to the longitudinal axis of the head.

To reduce turbulence within the head, the head preferably comprises means for directing fluid towards the neck. Therefore, in a third aspect the present invention provides a floor tool for a surface treating appliance, comprising a main body connected to a conduit, the conduit comprising a head pivotably connected to the main body for movement relative thereto, and a neck connected to the head, the head comprising a first port and a second port each for conveying fluid into the conduit from the main body, and means for directing the fluid entering the head through each port towards the neck.

The means for directing fluid towards the neck preferably comprises a plurality of guide surfaces located within the head and each for directing fluid entering the head through a respective port towards the neck. The guide surfaces are preferably integral with the inner wall of the head, with each guide surface preferably curving away from the inner wall of the head towards the neck.

To provide a compact floor tool, the head comprises an outer surface which is preferably substantially flush with an adjoining portion of the main body in both fully raised and fully lowered positions of the conduit. The adjoining portion of the main body preferably comprises an upper section of the main body, with this upper section being located towards the rear of the main body. Where the head of the conduit has a substantially cylindrical outer surface, the upper section of the main body preferably has a substantially semi-cylindrical portion adjoining each end of the head of the conduit, with the radius of the semi-cylindrical portion being substantially equal to the radius of the head of the conduit.

The main body preferably comprises means for supporting the head of the front section of the conduit. The means for supporting the head preferably comprises a support surface. Where the head is cylindrical in shape, the support surface preferably has a radius of curvature which is substantially the same as that of the head. The support surface is preferably located above part of a suction channel of the main body.

In the preferred embodiment the main body comprises a first suction channel for receiving a first dirt-bearing fluid flow, and a second suction channel for receiving the first dirt-bearing fluid flow from the first suction channel and a second dirt-bearing fluid flow. This "division" of the main body into two interconnected suction channels can enable two different pressure regions to be established within the main body. A relatively high vacuum may be established in the second suction channel, which optimises the performance of the floor tool for capturing dirt and dust located within crevices in the floor surface. Simultaneously, a relatively low vacuum may be established in the first suction channel, which can improve the performance of the floor tool for capturing debris located on the surface of the floor tool without significantly impairing the capture of dirt and dust within crevices.

The first suction channel is preferably located towards the front of the main body, whereas the second suction channel is preferably located towards the rear of the main body. The head of the front section of the conduit is preferably supported above the second suction channel. The second suction channel preferably comprises an enlarged central portion extending rearwardly away from the first suction channel to enhance stability as the floor tool is manoeuvred in a return stroke over the floor surface.

The floor tool preferably comprises flexible floor engaging means located about the suction channels and between the suction channels for maintaining the pressure levels within the suction channels over the articulation range of the floor tool. Therefore, in a fourth aspect the present invention provides a floor tool for a surface treating appliance, comprising a main body connected to a conduit, the main body comprising a first suction channel for receiving a first dirt-bearing fluid flow, a second suction channel for receiving the first dirt-bearing fluid flow from the first suction channel and a second dirt-bearing fluid flow, and for conveying the dirt-bearing fluid flows to the conduit, and flexible floor engaging means located about the suction channels and between the suction channels.

In the preferred embodiment, the floor tool comprises first flexible floor engaging means, preferably a plurality of bristles, filaments or at least one strip of flexible material, located about the suction channels, and second flexible floor engaging means, preferably also a plurality of bristles, filaments or at least one strip of flexible material, located between the first suction channel and the second suction channel. A series of relatively large castellations may be provided in a portion of the first floor engaging means adjacent the first suction channel to admit relatively large debris into the first suction channel during, for example, a forward stroke of the floor tool. A series of relatively small castellations may be provided in a portion of the first floor engaging means adjacent the second suction channel to admit relatively small debris into the second suction channel during, for example, a reverse stroke of the floor tool.

Dirt and debris may thus enter the second suction channel within three different fluid flows. A first dirt-bearing fluid flow enters the second suction channel from the first suction channel to convey relatively large surface-located debris into the second suction channel. A second dirt-bearing fluid flow enters the second suction channel through the relatively small castellations to convey relatively small surface-located debris into the second suction channel. A third dirt-bearing fluid flow enters the second suction channel between the first and second flexible floor engaging means to convey crevice- located dirt and debris into the second suction channel. The first and second dirt-bearing fluid flows may enter the second suction channel in substantially opposite directions, whereas the third dirt-bearing fluid flow may enter the second suction channel in a direction substantially orthogonal to one or both of the first and second dirt-bearing fluid flows.

The floor tool preferably comprises at least one intermediate channel located between the first suction channel and the second suction channel for conveying a fluid flow therebetween. The at least one intermediate channel is preferably co-planar with the suction channels, and may extend transversely to the suction channels. In the preferred embodiment the main body comprises a first intermediate channel and a second intermediate channel located on opposite sides of the main body. The intermediate channels may be defined by interruptions in the second floor engaging means, or by spaces between the first and second floor engaging means. Alternatively, or additionally, at least one intermediate channel may be formed in a housing of the main body which at least partially defines the suction channels.

In a fifth aspect the present invention provides a floor tool for a surface treating appliance, comprising a main body connected to a conduit, the conduit comprising a head pivotably connected to the main body for movement relative thereto between a fully raised position and a fully lowered position, the head comprising an outer surface which is substantially flush with an adjoining portion of the main body in both the raised and lowered positions.

Features described above in connection with the first aspect of the invention are equally applicable to the each of the second to fifth aspects of the invention, and vice versa.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view of a floor tool, with a conduit of the floor tool in a lowered position; Figure 2 is a bottom perspective view of the floor tool as positioned in Figure 1; Figure 3 is a top view of the floor tool as positioned in Figure 1; Figure 4 is a side view of the floor tool as positioned in Figure 1; Figure 5 is a front view of the floor tool as positioned in Figure 1; Figure 6 is a side sectional view along line V-V in Figure 3; Figure 7 is a front sectional view along line W-W in Figure 3; Figure 8 is a top sectional view along line X-X in Figure 5; Figure 9 is a top view of the floor tool of Figure 1, with the conduit in a raised position; Figure 10 is a side view of the floor tool as positioned in Figure 9; and Figure 11 is a front view of the floor tool as positioned in Figure 9.

With reference first to Figures 1 to 5, a floor tool 10 comprises a main body 12 and a conduit 14 connected to the main body 12. The main body 12 comprises an elongate casing 16 comprising a lower section 18 and an upper section 20 located towards the rear of the main body 12. The lower section 18 comprises a first, front suction channel 22 and a second, rear suction channel 24 located adjacent to, and in the same plane as, the front suction channel 22. In use, both suction channels 22, 24 face a floor surface to be cleaned. Each of the suction channels 22, 24 extends between opposite side edges 26, 28 of the casing 16. As illustrated most clearly in Figure 2, the rear suction channel 24 comprises an enlarged central portion 30 extending rearwardly away from the front suction channel 22 in the shape of a chevron to enhance stability as the floor tool 10 is manoeuvred over the floor surface.

The main body 12 comprises flexible floor engaging members located about the suction channels 22, 24, and between the suction channels 22, 24. In this embodiment, the floor engaging members comprises a first set of bristles 32 that is arranged in the form of a substantially continuous skirt about the suction channels 22, 24, and a second set of bristles 34 that is arranged in a substantially continuous linear row between the suction channels 22, 24. Alternatively, one or both of the sets of bristles 32, 34 may be replaced by at least one strip of flexible material. Each set of bristles 32, 34, is retained within a respective groove formed in the casing 16 of the main body 12. The first set of bristles 32 comprises a series of relatively large castellations 36 in the front section of these bristles 32, lying adjacent the front edge of the front suction channel 22, to admit relatively large debris into the front suction channel 22, for example, during a forward stroke of the floor tool 10. The first set of bristles 32 also comprises a series of relatively small castellations 38 in the rear section of these bristles 32, lying adjacent the rear edge of the rear suction channel 24, to admit relatively small debris into the rear suction channel 24, for example, during a reverse stroke of the floor tool 10.

Intermediate channels 40 are located between the front suction channel 22 and the rear suction channel 24 to provide fluid communication between the suction channels 22, 24.

The main body 12 comprises two intermediate channels 40 extending transversely between the suction channels 22, 24, with each intermediate channel 40 being located adjacent a respective side edge 26, 28 of the casing 16. In this embodiment, the row of bristles 34 does not extend fully between the side sections of the first set of bristles 32 so that each intermediate channel 40 is defined by a gap located between the first set of bristles 32 and a respective end of the row of bristles 34. Alternatively, the second set of bristles 34 may extend fully between the side sections of the first set of bristles 32, and at least one intermediate channel may be formed in the casing 16 of the main body 12 to convey fluid between the suction channels 22, 24.

The conduit 14 comprises a front section 50 and a rear section 52. The front section 50 is pivotably connected to the main body 12 for movement relative thereto about a first axis A1, indicated in Figures 3 and 6. The front section 50 comprises a head 54 pivotably connected to the main body 12, and a neck 56 extending from the head 54 to the rear section 52 of the conduit 14.

The head 54 is positioned within a recess located centrally in the upper section 20 of the casing 16. The head 54 has a longitudinal axis which is substantially co-linear with the first axis A1, and is connected to the upper section 20 of the casing 16 50 that the head 54 is free to rotate about its longitudinal axis. The head 54 has a substantially cylindrical outer surface 58 which is open at each end. The upper section 20 of the casing 16 is shaped so that each portion 60 of the upper section 20 that adjoins a respective end of the head 54 is substantially flush with the outer surface 58 of the head 54. Consequently, each portion 60 of the upper section 20 of the casing 16 has a substantially semi-cylindrical outer surface.

With particular reference to Figures 7 and 8, a sealing member 62 is provided between each end of the head 54 and its adjoining portion 60 of the upper section 20 of the casing 16 to form a substantially air-tight seal therebetween. Each end of the head 54 provides a respective port 64 through which fluid enters the conduit 14 from the main body 12. Each port 64 is thus substantially circular, and is substantially orthogonal to the longitudinal axis of the head 54, and therefore the first axis A1, which passes centrally through each port 64. As a result, in use fluid passes into the head 54 through the ports 64 is opposing directions.

The neck 56 is connected to the head 54 substantially midway between the ports 64, and in this embodiment is integral with the head 54. The neck 56 extends away from the head 54 in a direction which is substantially orthogonal to the longitudinal axis of the head 54. Consequently, as fluid passes through the head 54 from one of the ports 64 and into the neck, the fluid changes direction by around 90°. To reduce turbulence within the head 54, the head 54 comprises two guide surfaces 66, each for guiding fluid entering the head 54 through a respective port 64 towards the neck 56. The guide surfaces 66 are preferably integral with the inner surface 68 of the head 54, and arranged so that each guide surface 66 curves away from the inner wall 68 towards the neck 56 to meet the other guide surface 66 at an apex 70 extending across the bore of the head 54.

The bottom of the recess within the upper section 20 of the casing 16 is delimited by a curved support surface 72 for supporting the head 54 of the front section 50 of the conduit 14. The support surface 72 is located centrally within the rear suction channel 24, and extends between the front and rear edges of the rear suction channel 24. The support surface 72 preferably has a radius of curvature which is substantially the same as that of the outer surface 58 of the head 54. In addition to supporting the head 54, the support surface 72 also serves to guide fluid into the head 54 from the rear suction channel 24, and to support part of the lower surface of the neck 56 of the front section of the conduit 14 when the front section 50 is in its ftilly lowered position as illustrated in Figures 1 to 8.

Returning to Figure 6, the rear section 52 of the conduit 14 is connected to the neck 56 of the front section 50 of the conduit 14 for pivotal movement relative thereto about a second axis A2 angled to the first axis A1. In this embodiment the second axis A2 is orthogonal to the first axis A1, and is inclined to the longitudinal axis L of the rear section 52, illustrated in Figure 4, in this embodiment by an angle of around 65°.

The connection between the front section 50 and the rear section 52 of the conduit 14 is effected by connecting a fluid outlet 74 of the neck 56 of the front section 50 of the conduit 14 to a fluid inlet 76 of the rear section 52 of the conduit 14. The fluid outlet 74 of the neck 56 is substantially cylindrical, and is angled downwardly (as illustrated in Figure 6) towards a floor surface to be cleaned. The fluid inlet 76 of the rear section 52 is also substantially cylindrical and is angled upwardly (as illustrated in Figure 6) away from the floor surface so that when the fluid inlet 76 is received within the fluid outlet 74, the longitudinal axis L of the rear section 52 of the conduit 14 is substantially horizontal when the front section 50 of the conduit 14 is in its fully lowered position.

This enables the floor tool 10 to have a relatively low profile when in its frilly lowered position. The fluid inlet 76 of the rear section 52 is received within the fluid outlet 74 of the neck 56 so that the longitudinal axes of the fluid outlet 74 and the fluid inlet 76 are substantially co-linear with the second axis A2, and the fluid inlet 76 is rotatable relative to the fluid outlet 74 about the second axis A2. A sealing member 78 is located between the inner surface of the fluid inlet 74 and the outer surface of the fluid outlet 76 to inhibit fluid loss from therebetween.

The rear section 52 of the conduit 14 comprises a fluid outlet 80 which is connectable to a wand, hose or other such duct of a cleaning appliance which comprises dirt and dust separating apparatus and a motor-driven fan unit for drawing dirt-bearing fluid into the main body 12 of the floor tool 10.

In use, with the floor tool 10 located on a floor surface so that both the first set of bristles 32 and the second set of bristles 34 engage the floor surface, operation of the fan unit generates two different pressure regions within the main body 12. Due to the relatively tight seal formed around the rear suction channel 24 by the two sets of bristles 32, 34, a relatively high vacuum can be established in the rear suction channel 24. This can optimise the entrainment of dust and debris located within crevices in the floor surface within a fluid flow drawn into the rear suction channel 24 between the two sets of bristles 32, 34. A relatively small amount of this vacuum is sacrificed by the provision of (i) the relatively small castellations 38 in the first set of bristles 32, to enable dust and relatively small debris located on the floor surface to be entrained within a fluid flow drawn though the relatively small castellations 38 into the rear suction channel 24, and (ii) the intermediate channels 40 between the first set of bristles 32 and the second set of bristles 34.

The provision of the relatively small castellations 38 can reduce the amount of debris that builds up along the rear edge of the main body 12 as the floor tool 10 is manoeuvred in a reverse direction over the floor surface. On the other hand, the provision of these intermediate channels 40 establishes a relatively low vacuum in the front suction channel 22 to enable dust and relatively large debris located on the floor surface to be entrained within a fluid flow drawn into the front suction channel 22 through the relatively large castellations 36. This first, dirt-bearing fluid flow is conveyed from the front suction channel 22 through the intermediate channels 40 to the rear suction channel 24, where it merges with fluid drawn directly into the rear suction channel 24. The merged fluid flow passes into the upper section 20 of the casing 16 and through the ports 64 into the head 54 of the front section 50 of the conduit 14. The guide surfaces 66 within the head 54 guide the fluid flow into the neck 56. From the neck 56, the fluid flow passes into the rear section 52 of the conduit 14, and into a wand (not shown) connected to the fluid outlet 80 of the rear section 52.

As the floor tool 10 is manoeuvred over the floor surface, the flexibility of the bristles 32, 34 can enable the contact between the bristles 32, 34 and the floor surface, and thus the two different pressure regions within the main body 12, to be maintained over a wide range of orientations of the wand relative to the main body 12. Figures 1 to 8 illustrates the conduit 14 in a fully lowered position, in which the upper extremity of the floor tool 10 is only slightly higher than the uppermost extremity of the head 54 of the front section 50 of the conduit 14. This can enable the floor tool 10 to be manoeuvred beneath, for example, items of furniture located on the floor surface whilst maintaining contact between the bristles 32, 34 and the floor surface. During use, the conduit 14 can be raised from this fully lowered position, for example to facilitate manoeuvring of the floor tool 10 over an open floor surface, by raising the wand (not shown) connected to the fluid outlet 80, thus causing the head 54 of the front section 50 of the conduit 14 to pivot about the first axis A1.

By way of example, the front section 50 of the conduit 14 can be raised from the fully lowered position shown in Figures 1 to 8 to a raised position, shown in Figures 9 to 11, by pivoting the front section 50 of the conduit 14 relative to the main body 12 about an angle of around 110°. Simultaneously with, or separately from, the pivoting of the front section 50 of the conduit 14 relative to the main body 12, the rear section 52 of the conduit 14 may be pivoted relative to the front section 50 of the conduit 14 by turning the wand relative to the main body 12, which causes the fluid inlet 76 to rotate relative to the fluid outlet 74. For example, in the raised position shown in Figures 9 to lithe rear section 52 of the conduit 14 has been pivoted relative to the front section 50 of the conduit 14 by around 40°. In this raised position, a wand connected to the fluid outlet 80, may be substantially parallel to the main body 12 of the floor tool, enable the floor tool 10 to be pushed and pulled sideways by the user, for example into a relatively narrow gap between items of furniture or between an item of furniture and a wall, whilst maintaining the bristles 32, 34 in contact with the floor surface.

The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art

Claims

CLAIMS1. A floor tool for a surface treating appliance, comprising a main body connected to a conduit, the conduit comprising a head pivotably connected to the main body for movement relative thereto, and a neck connected to the head, the head comprising a first port and a second port each for conveying fluid into the conduit from the main body, and means for directing fluid entering the head through each port towards the neck.
2. A floor tool as claimed in claim 1, wherein the fluid directing means comprises a plurality of guide surfaces located within the head and each for guiding fluid entering the head through a respective port towards the neck.
3. A floor tool as claimed in claim 2, wherein the guide surfaces are integral with the inner wall of the head
4. A floor tool as claimed in claim 3, wherein each guide surface curves away from the inner wall towards the neck.
5. A floor tool as claimed in any of the preceding claims, wherein the head is pivotable relative to the main body about a pivot axis, the pivot axis passing through the first port and the second port.
6. A floor tool as claimed in any of the preceding claims, wherein the neck of the conduit is pivotable relative to the main body about an angle of at least 60°, preferably of at least 80°.
7. A floor tool as claimed in any of the preceding claims, wherein the head is substantially cylindrical.
8. A floor tool as claimed in any of the preceding claims, wherein the first port and the second port are substantially concentric.
9. A floor tool as claimed in any of the preceding claims, wherein the head has a longitudinal axis, and the ports are substantially orthogonal to the longitudinal axis of the head.
10. A floor tool as claimed in claim 9, wherein the longitudinal axis is co-linear with the pivot axis.
11. A floor tool as claimed in any of the preceding claims, wherein the neck is connected to the head substantially midway between the ports.
12. A floor tool as claimed in any of the preceding claims, wherein the outer surface of the head is substantially flush with an adjoining portion of the main body.
13. A floor tool as claimed in any of the preceding claims, wherein the main body comprises means for supporting the head of the conduit.
14. A floor tool as claimed in claim 13, wherein the means for supporting the head comprises a support surface.
15. A floor tool as claimed in claim 14, wherein the main body comprises a suction cavity, and wherein the support surface is located above part of the suction cavity.
16. A floor tool for a surface treating appliance substantially as hereinbefore described with reference to the accompanying drawings.