I claim:
1. A heater having a tip, said heater comprising:
(a) an electrode;
(b) an insulative layer disposed over the outer surface of said electrode;
(c) a resistive layer disposed over said insulative layer such that a substantial portion of the volume of said resistive layer is disposed in close proximity to the tip of the heater; and
(d) a conductive layer which is disposed over said insulative layer.
2. The heater of claim 1, having a base portion formed at the first end of said electrode such that the diameter of the base portion is substantially the same as the diameter of the conductive layer.
3. The heater of claim 1, wherein said electrode is electrically conductive.
4. The heater of claim 1, wherein said electrode has a positive temperature coefficient of resistance.
5. The heater of claim 1, wherein said conductive layer has a negative temperature coefficient of resistance.
6. The heater of claim 1, wherein a first portion of said electrode has a resistance that varies with temperature and a second portion of said electrode is electrically conductive, said first portion of the electrode being disposed in close proximity to the tip of the heater and said second portion abutting said first portion in close proximity to the tip of the heater.
7. The heater of claim 6, wherein said first portion has a positive temperature coefficient of resistivity.
8. The heater of claim 6, wherein said second portion has a negative temperature coefficient of resistivity.
9. The heater of claim 6, wherein said second portion is an inner conductive layer disposed between said first portion of electrode and said insulative layer.
10. The heater of claim 9, wherein said inner conductive layer has a negative temperature coefficient of resistivity.
11. The heater of claim 6, wherein said second portion is a conductive core disposed within said electrode.
12. The heater of claim 6, wherein said conductive core has a negative temperature coefficient of resistivity.
13. The heater of claim 1, wherein said resistive layer extends back from the tip of said heater between the insulative layer and the conductive layer along a substantial length of the heater.
14. The heater of claim 1, wherein said resistive layer extends back from the tip of said heater over the insulative layer and the conductive layer along a substantial length of the heater.
15. A ceramic glow plug comprising the heater according to claim 1.
16. The heater of claim 1, wherein said electrode, said insulative layer, said resistive layer, and said conductive layer are all manufactured from ceramic materials.
17. The heater of claim 1, wherein the electrode, the insulative layer, the resistive layer and the conductive layer are slip cast to form a green body.
18. The heater of claim 17, wherein the green body is dipped into conductive ceramic slurry to form the conductive layer.
19. A heating system comprising the heater according to claim 1,
wherein an electrical resistance device for measuring the temperature of the heater and having an output is coupled to the heater, and a variable power supply is coupled to the output of the resistance device, said resistance device causing said variable power supply to increase the power provided to said heater if said temperature falls below a first predetermined level and causing said variable power supply to provide less power to said heater if said temperature rises above a second predetermined level.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Wheel-mounting device comprising
a pair of plates each having a substantially flat surface,
said flat surface of each plate having therein an elongated indentation including an inwardly projecting dimple element,
said indentations each including an open external end portion at an edge of the plate in which the indentation is situated,
said plates being attached together with said flat surfaces abutting and the indentations being aligned and facing each other to form a cavity upon attachment of the plates,
said dimple elements being aligned along a common line and pointing towards each other and separated by a predetermined distance upon attachment of the plates,
said open external end portions of the indentations forming at an outer end of the cavity an open entryway along the edges of the abutting and attached plates.
2. The wheel-mounting device of claim 1 where the plates are substantially mirror images.
3. The wheel-mounting device of claim 1 where each plate comprises a carrier portion and a wing portion along an outer edge of the carrier portion.
4. The wheel-mounting device of claim 3 where each wing member is substantially at 90 degrees with respect to the plate.
5. A wheel-mounting device comprising
a pair of metallic plates each having a substantially flat surface,
an elongated indentation in the flat surface of each plate including an inwardly projecting dimple element, said indentation and dimple element formed by punch pressing the metallic plate,
said indentations being substantially mirror images and each indentation including an open external end portion at an edge of the plate in which the indentation is situated,
said plates being attached together with said flat surfaces abutting and the indentations being aligned and facing each other to form a cavity upon attachment of the plates,
said open external end portions of the indentations forming at an outer end of the cavity an open entryway along the edges of the plates,
said dimple elements upon attachment of the plates being aligned along a common line and pointing towards each other, the aligned dimple elements being at or near an inner end of the cavity and separated by a predetermined distance that enable the dimple elements to prevent a wheel shaft from moving lengthwise out the open entryway when said shaft is received within the cavity.
6. The wheel-mounting device of claim 5 where a portion of the attached plates form a stop member at an inner end of the cavity opposite the open entryway to limit inward movement lengthwise of the shaft.
7. The wheel-mounting device of claim 1 where each plate has a wing member formed by bending the metallic plate substantially at 90 degrees, said wing member facilitating detachably connecting the wheel-mounting device to a bed frame.
8. A combination of a wheel-mounting device and a wheel where the wheel-mounting device comprises
a pair of plates each having a substantially flat surface,
said flat surface of each plate having therein an elongated indentation including an inwardly projecting dimple element,
said indentations being substantially mirror images and each indentation including an open external end portion at an edge of the plate in which the indentation is situated,
said plates being attached together with said flat surfaces abutting and the indentations being aligned and facing each other to form a cavity upon attachment of the plates,
dimple elements being aligned along a common line and pointing towards each other and separated by a predetermined distance upon attachment of the plates,
said open external end portions of the indentations forming at an outer end of the cavity an open entryway along the edges of the plates, and
the wheel being mounted to the lower end of the shaft and comprising
an elongated shaft seated in the cavity and having an upper end portion including an enlarged element having a width dimension greater than said predetermined distance between the dimple elements and a predetermined length that enables a lower end to extend from the open entryway,
said enlarged element being at or nearby the inner end of the cavity and inward of the dimple elements with the plates attached to hold said shaft within the cavity and prevent movement lengthwise out the open entryway.
9. The combination of claim 8 where a portion of the attached plates form a stop member at an inner end of the cavity opposite the open entryway to limit lengthwise inward movement of the shaft.
10. The combination of claim 8 the shaft includes a central main body portion with a diameter less than said predetermined distance between the dimple elements and the enlarged element is a substantially annular member having a diameter greater than the diameter of the main body portion, and the lower end has a diameter greater than said predetermined distance between the dimple elements and greater than the diameter of the main body portion.
11. The combination of claim 10 where the cavity has a substantially cylindrical configuration with a predetermined diameter and the annular member and the lower end of the shaft have a diameter less than the predetermined diameter of the cylindrical cavity.
12. The combination of claim 10 where the plates include a plurality of punched pressed holes therein and fasteners passing through said holes.
13. The combination of claim 12 where the holes are at or nearby corners of the said plates.
14. A bed frame including
at least one leg having a wheel assembly mounted thereto by a mounting device,
said mounting device comprising
a pair of plates each having a substantially flat surface,
said flat surface of each plate having therein an elongated indentation including an inwardly projecting dimple element,
said indentations each including an open external end portion at an edge of the plate in which the indentation is situated,
said plates being attached together with said flat surfaces abutting and the indentations being aligned and facing each other to form a cavity upon attachment of the plates,
said dimple elements being aligned along a common line and pointing towards each other and separated by a predetermined distance upon attachment of the plates,
said open external end portions of the indentations forming at an outer end of the cavity an open entryway along the edges of the abutting and attached plates, and
each said wheel assembly comprising
an elongated shaft seated in the cavity and having an upper end portion including an enlarged element having a width dimension greater than said predetermined distance between the dimple elements and a predetermined length that enables a lower end to extend from the open entryway,
said enlarged element being at or nearby the inner end of the cavity and inward of the dimple elements with the plates attached to hold said shaft within the cavity and prevent movement lengthwise out the open entryway, and
a wheel mounted to the lower end of the shaft.
15. A plate for mounting a wheel assembly including a shaft having a predetermined length and an enlarged element a predetermined distance from a terminal end of the shaft, said plate being formed from a single piece of substantially flat sheet metal that is bent into a substantially L-shaped configuration and comprising
a carrier portion and a wing portion that are integral along a common junction and substantially at a right angle with respect to each other,
said carrier portion having a substantially flat inside surface,
said flat surface having therein an elongated indentation including an inwardly projecting dimple element,
said indentation including an open external end portion at an edge of the plate and having a length that is substantially equal that of the length of the shaft,
a dimple element pointing inward and at a predetermined distance from said edge that is substantially equal to the distance the enlarged element is from the terminal end of the shaft.
16. A method of manufacturing a wheel-mounting device comprising
providing a pair of plates that are substantially mirror images, each plate having a substantially L-shaped configuration and being manufactured from substantially flat metallic sheets punch pressed and bent into said L-shaped configuration, each plate including a wall with an indentation therein, said indentation including an inwardly projecting dimple element and having an open end along an edge,
fastening together said plates with the walls of the plates abutting each other with the indentations aligned to form a cavity having along the edges an entryway adapted to receive a shaft of a wheel,
said dimples being aligned opposite each other and spaced apart to hold a shaft of a wheel in the cavity.
17. The method of claim 16 where the shaft is inserted into the entryway of the cavity after fastening the plates together.
18. The method of claim 16 where the shaft is placed between the plates and then the plates are fastened together.