GB2252814A - Rotary knob assemblies for electrical components - Google Patents

Abstract

An electrical component e.g. potentiometer (6) is connected to a panel member (2) by way of a nut (12), and a knob (14) engages with a shaft (8) of the component. The rotary knob (14) and the lock nut (12) are arranged to form an assembly with a distinctive visual appearance, and the assembly acts to centre the electrical component, and to determine the exact height of the knob above the panel member (2). In the assembled position, a reduced diameter part (32) of the nut (12) is received within an open end (20) of the knob (14). Thus, when the knob (14) is assembled on the shaft (8), the two cylindrical parts (22, 32) are adjacent and together define a substantially continuous profile. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO ROTARY KNOBS FOR ELECTRICAL COMPONENTS The present invention relates to a rotary knob and lock nut assembly for an electrical component, and to a panel assmebly for an electrical component.

Potentiometers and other electrical components can be supported on a panel by providing them with an externally threaded part which is arranged to extend through the panel. A lock nut, and generally a washer, is then engaged on the threaded part to secure the component on the panel.

Where the potentiometer or other electrical component has a rotatable shaft, this shaft is arranged to extend through the threaded part of the component, and hence through the panel, and a rotary knob is then engaged on the shaft. The knob is fixed on the shaft by a non-rotational connection, for example, is a push fit thereon, such that rotation of the knob rotates the shaft.

Although such arrangements are generally satisfactory, the visual appearance of a panel carrying a number of electrical components, and therefore provided with a number of such knobs, can be displeasing. Thus, the lock nuts are clearly visible, and often there is a gap between each nut and, any associated washer, and the base of the knob. Each knob is pushed onto the shaft until the closed end of the knob contacts the shaft. This makes it difficult to arrange for knobs associated with potentiometers supporting potentiometer brackets, for example, to be positioned at the same height above the panel as knobs on other potentiometers or electrical components. In addition, manufacturing tolerances can mean that all the knobs in a group are at slightly differing heights above the panel.

Not only is this visually displeasing, where there are a large number of knobs in a small area, this can make it difficult for a user not to favour a more prominent knob over the others.

It is an object of the present invention to provide a rotary knob and lock nut assembly which reduces the noted disadvantages.

According to a first aspect of the present invention there is provided rotary knob and lock nut assembly for an electrical component, said assembly comprising a hollow rotary knob arranged to receive a rotatable shaft therein and having first and second opposed ends, at least said second end being open, and a generally annular lock nut having an internal screw thread, an external periphery, and opposed substantially annular end surfaces, one of said end surfaces defining a support surface, wherein said external periphery of said lock nut is sized and shaped such that at least part thereof is receivable within the second, open end of said rotary knob, and wherein, when said part of said lock nut is received within said knob, said lock nut and/or said rotary knob define a continuous profile extending from the first end of said knob to said support surface of said nut.

In the assembled position of the knob and the nut, a continuous profile is defined which extends from the first end of the knob to the support surface of the nut. The resultant assembly is thereby given a visual appearance which is much more pleasing than that of known assemblies.

The knob and the nut are preferably made of the same material, and are preferably of the same colour. For example, in a preferred embodiment both said knob and said nut are made of plastics material. Preferably, the knob and the nut are moulded from the plastics material.

In one embodiment, the external periphery of said lock nut is stepped to define a first part of reduced diameter which is connected by way of a radial flange portion to a second part of greater diameter. In the assembled position, the reduced diameter part is arranged to be received within the second, open end of said knob, and said open end is arranged to abut or be proximate to said flange portion of said nut. The external diameter of said knob adjacent its open end is preferably substantially the same as the external diameter of said second part of the nut whereby a substantially continuous surface is defined by the knob and the nut.

In an alternative embodiment, in the assembled position substantially all of the nut is arranged to be received within the open end of said knob whereby the surface of the knob continues to the support surface of said nut.

The rotary knob may be substantially cylindrical in shape with a generally circular cross-section.

Alternatively, the knob may be formed as a truncated cone.

If required, the knob may be flanged along its longitudinal extent. For example, the knob may be cylindrical or conical and be provided with a portion adjacent its second, open end of a larger diameter than the rest of the knob. A cylindrical knob may be provided and have a generally conical increased diameter portion adjacent its second end, or a substantially conical knob may be provided with a generally cylindrical portion of increased diameter adjacent its second, open end. It is also possible for the cross-section of the knob either along all of its length, or along part thereof, to be ovoid, elliptical, or any other shape. For example, the cross-section may approximate to that of a square with radiused corners.

Whatever the basic shape of the knob, the outside surface may be substantially plain, or may be provided with corrugations, fluting, projections or the like.

At least the part of the lock nut which is arranged to extend within the second, open end of the knob is preferably cylindrical with a circular cross-section.

However, any part of the lock nut which is visible is preferably arranged to have substantially the same shape as the external shape of an adjacent part of said knob.

In a preferred embodiment, the support surface of said lock nut has a centrally disposed depending portion defining a circumferential surface. Preferably, said circumferential surface is arranged centrally of the support surface and depends therefrom. This circumferential surface acts as a centering means for the lock nut, and hence for the electrical component on which it is to be engaged.

Said lock nut and/or said rotary knob is preferably arranged to carry one or more bearing surfaces. For example, the end surface of the lock nut remote from said support surface may carry one or more beads. Additionally and/or alternatively, the end surface of the lock nut remote from said support surface may be arranged to carry or form a bearing surface.

In a preferred embodiment the external periphery of said lock nut is stepped to define a first part of reduced diameter which is connected to a second part of greater diameter. Said support surface is comprised by the end surface of said greater diameter part, whereas the end surface of said reduced diameter part defines said bearing surface. A In a preferred embodiment, said rotary knob is provided with an internal bearing surface within the second, open end thereof. In a preferred embodiment, the bearing surface of said knob is a substantially planar, annular surface.

Preferably, said lock nut is provided with engagement means arranged inwardly of any part of said lock nut which is arranged to define a continuous profile with said rotary knob. This ensures that any visible part of the lock nut is kept from being damaged during tightening of the nut.

For example, where the nut is arranged to have a first reduced diameter part and a second part of greater diameter, said engagement means are provided inwardly of the outer surface of said greater diameter part.

In one embodiment, said engagement means comprise one or more slots extending in or through said reduced diameter part.

Additionally and/or alternatively, said engagement means comprise one or more bores extending substantially longitudinally of said nut radially inwardly of the outer surface of said greater diameter part.

According to a further aspect of the present invention there is provided a panel assembly comprising a substantially planar panel having a bore therethrough, an electrical component having an externally threaded part extending through said bore to project relative to the panel, said component having a rotatable shaft extending through said threaded part, wherein said electrical component is fixed relative to said panel by way of an internallyAthreaded lock nut engaged on said threaded part, and further comprising a rotary knob connected to and surrounding said rotatable shaft, said lock nut and/or said rotary knob extending to proximate said panel.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an exploded perspective view illustrating a rotary knob and nut assembly of the present invention for securing an electrical component to a panel member, Figure 2 shows a perspective view of the rotary knob and lock nut assembly of Figure 1 in its assembled position, Figure 3 shows a longitudinal section of the assembled knob and lock nut assembly when supporting the electrical component relative to the panel member, Figure 4a shows an elevation of the lock nut of Figure 3, Figure 4b shows a plan view from above of the lock nut of Figure 4a, Figure 5 shows an end elevation, partly in section, of an alternative embodiment of a rotary knob and nut assembly of the invention, Figure 6a shows a longitudinal section of an alternative embodiment of a lock nut of the invention, and Figure 6b shows a plan view from above of the lock nut of Figure 6a.

Figure 1 shows an exploded perspective view of a rotary knob and lock nut assembly of the invention used to support an electrical component 6 relative to a substantially planar panel member 2. This panel member 2, for example, may be the wall of a cabinet of a mixing console ort other electrical device having one or more electrical components each controlled by way of a respective rotatable shaft. Each electrical component is secured relative to the cabinet wall such that its rotatable shaft extends therethrough, and a respective rotary knob is then mounted on the shaft to enable adjustment of the electrical component by a user.

As shown in Figure 1, the electrical component 6, for example a potentiometer, is provided with an externally threaded cylindrical part 10 through which a rotatable shaft 8 extends. The component 6 is positioned adjacent the panel member 2 such that the threaded part 10 and the shaft 8 extend through a bore 4 therein. An internally threaded lock nut 12 of the knob and nut assembly is then engaged on the threaded part 10 to support the component 6 on the panel member 2. In this position the shaft 8 projects relative to the outer surface of the panel member 2. A rotary knob 14 of the knob and nut assembly is then connected to the shaft 8 such that relative rotation between the knob 14 and the shaft 8 is not possible.

Rotation of the knob 14 thus causes rotation of the shaft 8 and thereby adjusts the component 6. For example, where the component 6 is a potentiometer, rotation of the knob 14 varies its resistance. In the embodiment illustrated in Figure 1, the shaft 8 is provided with a flattened area 16 for engagement within the rotary knob 14 to provide the necessary non-rotational connection.

Of course, the connection of an electrical component as 6 to a panel member 2 by way of a nut is well known. It is also known to provide a knob to engage with a shaft of the component. However, the rotary knob 14 and the lock nut 12 illustrated differ from known arrangements in that the two items are arranged to form an assembly with a distinctive visual appearance and in which the usual gap between the nut and the knob is not formed. Furthermore, the knob and nut assembly of the invention acts to centre the electrical component, and also to determine the exact height of the knob above the panel member. It is also unnecessary to use a washer with an assembly of the invention.

As can be seen in Figures 1 to 3, the rotary knob 14 is an elongate hollow member which is substantially cylindrical and which is arranged to receive the shaft 8 therein. The rotary knob 14 has a first, closed end 18, and a second, open end 20 remote from and opposed to said closed end. In the embodiment illustrated, the rotary knob 14 is substantially cylindrical but is provided with a part of increasing diameter adjacent to its open end 20. At the open end 20, the knob is formed to have a substantially cylindrical end portion 22 which is greater in diameter than the remaining part of the knob 14.

In the embodiment illustrated, the main part of the knob 14 is provided with longitudinally extendig fluting, illustrated at 24, around its periphery. The knob is also provided with an integrally formed, longitudinally extending projection 26 which is arranged to form a pointer for the knob. Preferably, the knob 14 is moulded from plastics material.

The lock nut 12 which forms an assembly with the knob 14 is also preferably moulded from a plastics material.

The lock nut 12 is an internally threaded, generally annular member having opposed substantially annular end surfaces 28 and 30. It will be seen that the external periphery of the lock nut 12 is stepped to define a first part 32 of reduced diameter which is connected by way of a radial flange 34 to a second part 36 having a greater diameter. In the embodiment illustrated the second part 36 of greater' diameter is substantially cylindrical, whereas the reduced diameter part 32 is substantially conical. The flange portion 34 is, as can be seen from Figure 1, a substantially planar, radially extending flange.

As can be seen in Figure 3, in the assembled position, the support surface 28 of the nut 12 is arranged to abut the outer surface of the panel member 2, and the internal screw thread of the nut 12 is engaged with the external screw thread of the threaded part 10 of the electrical component 6. It will be seen that the conical, reduced diameter, part 32 of the nut 12 is received within the open end 20 of the knob 14. It will also be appreciated, for example from Figures 2 and 3, that the cylindrical part 22 of the knob 14 and the cylindrical part 36 of the nut 12 are substantially of the same diameter. Thus, when the knob 14 is assembled on the shaft 8, the two cylindrical parts 22, 32 are adjacent and together define a substantially continuous profile.It will therefore be seen that the knob 14 and the nut 12 together define a substantially continuous profile which extends from the closed end 18 of the knob 14 to the panel member 2.

As can be seen in Figures 3 and 4a, the support surface 28 of the lock nut 12 is formed to have a substantially centrally deposed depending portion 40 which defines a circumferential surface 42. In the embodiment illustrated, this circumferential surface 42 is substantially conical in shape. It will be appreciated from Figure 3, that the circumferential surface 42 acts to centre the nut 12 within the bore 4 of the panel member 2.

The surface 42 therefore acts as centering means for the threaded part 10 of the electrical component 6 and hence for its shaft 8. In this manner, as the component 6 is secured to the panel member 2 by the nut 12 it is accurately centred relative to the bore 4.

As seen in Figure 3, the support surface 28 of the nut 12 is engaged on the outer surface of the panel member 2 thereby positioning the upper end surface 30 of the nut at a predetermined position above the panel member 2. This is used, in the invention, to determine the position of the rotary knob 14. In this respect, and as can be seen in Figure 3, the knob 14 is provided with an internal, substantially planar, annular, radially extending flange 44 inwardly of said open end 20. When the knob 14 is positioned on the shaft 8, the flange 44 is arranged to contact the upper end surface 30 of the nut 12 which thereby forms a bearing surface. The bearing surface 30 positively determines the position of the knob 14 relative to the panel member 2, and also provides a surface on which the knob 14 can rotate.

In most currently known arrangements, a knob is push fitted onto the shaft until the end of the shaft engages at the end of the bore within the knob. This means that differences in the length of the shaft and/or in the length of the bore within the knob determine the height of the knob above the panel. If one electrical component is to support a bracket between it and the panel member, for example, it is difficult to arrange for its knob to be at the same height above the panel as a neighbouring knob associated with a component without such a bracket. In addition, the manufacturing tolerances utilised generally mean that with known arrangements, neighbouring knobs are at clearly differing heights above the panel.

In the embodiment shown in Figure 1, the end surface 30 of the lock nut 12 itself forms the bearing surface.

However, and as indicated in Figures 3, and 4a and 4b, a raised bearing surface 46 may be provided on the end surface 30. Such a raised surface as 46 has a small radial dimension, and is generally preferred as it provides a better surface for the rotation of the knob 14.

As the external cylindrical surface of the greater diameter part 36 of the nut 12 is to form part of the continuous profile of the knob and nut assembly, it is important that it not be damaged during assembly.

Accordingly, the conical part 32 of the nut 12 is provided with radially extending slots 48 forming engagement means for engagement by a tool to rotate the nut during assembly.

Of course, alternative engagement means may be provided.

In the embodiments so far described, the knob 14 is arranged adjacent the nut 12 such that the knob and nut together form a continuous profile for the assembly.

Figure 5 illustrates an alternative embodiment in which a nut 12' is arranged in the assembled condition to be received almost entirely within a knob 14' whereby the continuous profile of the knob 14' forms the continuous profile of the assembly. The arrangement of Figure 5 is generally more appropriate for knobs of a larger diameter.

The nut 12' is preferably provided with centering means as discussed above and also with a bearing surface for engagement with an appropriate flange formed within the knob 14'.

It has been said that the nut 12 or 12' is preferably made of a plastics material. This enables the nut to act as its own anti-shake device, such that a washer is not required.

Figures 6a and 6b show an alternative construction of a nut for an assembly of the invention having a similar construction to the nuts 12 and 12', but having alternative engagement means. Thus, the nut 112 shown in longitudinal section in Figure 6a has a cylindrical portion 136 connected by way of a radial flange 134 to a conical portion 132. However, in this embodiment of the nut, the engagement means comprise a plurality of longitudinally extending bores 148 extending through the conical portion, the flange 134 and the cylindrical portion 136. It will be appreciated that a tool may be engaged with one or more of the bores 148 to enable rotation of the nut 112 so as to secure the electrical component in position.

In the embodiments illustrated, the rotary knob 14 is shown to have a first, closed end 18. Of course, if the knob is to be used with a dual concentric potentiometer, for example, the first end thereof may be open.

It will be appreciated that modifications to and variations in the present invention as described above may be made within the scope of the present application.

Claims (14)

1. A rotary knob and lock nut assembly for an electrical component, said assembly comprising a hollow rotary knob arranged to receive a rotatable shaft therein and having first and second opposed ends, at least said second end being open, and a generally annular lock nut having an internal screw thread, an external periphery, and opposed substantially annular end surfaces, one of said end surfaces defining a support surface, wherein said external periphery of said lock nut is sized and shaped such that at least part thereof is receivable within the second, open end of said rotary knob, and wherein, when said part of said lock nut is received within said knob, said lock nut and/or said rotary knob define a continuous profile extending from the first end of said knob to said support surface of said nut.

2. A rotary knob and lock nut assembly as claimed in Claim 1, wherein the external periphery of said lock nut is stepped to define a first part of reduced diameter which is connected by way of a radial flange portion to a second part of greater diameter and wherein, in the assembled position, the reduced diameter part of said lock nut is arranged to be received within the second, open end of said knob, and said open end is arranged to abut or be proximate to said flange portion of said nut.

3. A rotary knob and lock nut assembly as claimed in Claim 2, wherein the external diameter of said knob adjacent its open end is preferably substantially the same as the external diameter of said second part of the nut whereby a substantially continuous surface is defined by the knob and the nut.

4. A rotary knob and lock nut assembly as claimed in Claim 1, wherein, in the assembled position, substantially all of the lock nut is arranged to be received within the open end of said knob whereby the surface of the knob continues to the support surface of said nut.

5. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein said rotary knob is substantially cylindrical or conical in shape with a generally circular cross-section, and wherein the knob is provided with a portion adjacent its second, open end of a larger diameter than the rest of the knob.

6. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein the support surface of said lock nut has a centrally disposed depending portion defining a circumferential surface which is arranged to act as a centering means for the lock nut.

7. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein said lock nut and/or said rotary knob is arranged to carry one or more bearing surfaces, for example, such as beads.

8. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein the external periphery of said lock nut is stepped to define a first part of reduced diameter which is connected to a second part of greater diameter, and wherein said support surface is comprised by the end surface of said greater diameter part, and the end surface of said reduced diameter part defines a bearing surface.

9. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein said rotary knob is provided with an internal bearing surface within the second, open end thereof, and wherein said bearing surface of the knob is a substantially planar, annular surface.

10. A rotary knob and lock nut assembly as claimed in any preceding claim, wherein said lock nut is provided with one or more slots or bores arranged inwardly of any part thereof which is arranged to define a continuous profile with said rotary knob, said slots or bores forming engagement means.

11. A panel assembly comprising a substantially planar panel having a bore therethrough, an electrical component having an externally threaded part extending through said bore to project relative to the panel, said component having a rotatable shaft extending through said threaded part, wherein said electrical component is fixed relative to said panel by way of an internally threaded lock nut engaged on said threaded part, and further comprising a rotary knob connected to and surrounding said rotatable shaft, said lock nut and/or said rotary knob extending to proximate said panel.

12. A panel assembly as claimed in Claim 11, and supporting one or more rotary knob and lock nut assemblies as claimed in any of Claims 1 to 10.

13. A rotary knob and lock nut assembly substantially as hereinbefore described with reference to the accompanying drawings.

14. A panel assembly substantially as hereinbefore described with reference to the accompanying drawings.