Voice coil speaker with conductive cooling
View Patent ↗Example embodiments provide a voice coil speaker that may comprise a speaker frame and a diaphragm connected to the speaker frame and configured to be capable of axial movement. A heat conducting coil former may be connected to the diaphragm. A pole piece and a back plate may form an annular gap and conduct magnetic flux from an axially polarized permanent magnet in a complete loop that includes the annular gap. A voice coil may be wound on the heat conducting coil former and residing in the annular gap, the magnetic flux passing through the voice coil in the radial direction, such that the voice coil produces an axial force to cause the diaphragm to produce sound. A thermal bridge may be configured to conduct heat from the heat conducting coil former to the back plate.
1 . A voice coil speaker comprising:
a speaker frame;
a diaphragm connected to the speaker frame and configured to be capable of axial movement;
an axially polarized permanent magnet;
a back plate;
a heat conducting coil former connected to the diaphragm, and surrounded by a sleeve;
a pole piece, wherein the pole piece and the back plate form an annular gap and conduct magnetic flux from the axially polarized permanent magnet in a complete loop that includes the annular gap;
a voice coil wound on the heat conducting coil former and residing in the annular gap, the magnetic flux passing through the voice coil in the radial direction, such that the voice coil produces an axial force to cause the diaphragm to produce sound; and
a thermal bridge configured to conduct heat from the heat conducting coil former to the back plate,
wherein the heat conducting coil former includes a groove into which the voice coil is wound to ensure thermal contact between the voice coil and the heat conducting coil former, the groove being an opening within the heat conducting coil former and covered by the sleeve, such that the voice coil is enclosed within the heat conducting coil former and covered by the sleeve.
2 . The voice coil speaker of claim 1 , wherein
the axial force is produced by the interaction of the voice coil with the radial magnetic field when subjected to electrical current flow,
the axial force causes axial movement of the diaphragm; and
the diaphragm causes alternating compression and rarefaction of the contacting air to produce the sound.
3 . The voice coil speaker of claim 1 , wherein heat is conducted radially and axially from the voice coil into the heat conducting coil former.
4 . The voice coil speaker of claim 1 , wherein the heat conducting coil former is made of material with high thermal conductivity and conducts heat from the voice coil axially to the thermal bridge.
5 . The voice coil speaker of claim 4 , wherein the material with high thermal conductivity is at least one of aluminum or copper.
6 . The voice coil speaker of claim 1 ,
wherein the heat conducting coil former includes a plurality of axial slits to prevent eddy currents from being induced in the heat conducting coil former by a current through the voice coil or by relative motion of the heat conducting coil former with the magnetic field in the annual gap,
wherein the plurality of axial slits extend past a point of maximum travel of the heat conducting coil former in the annular gap.
7 . The voice coil speaker of claim 1 , wherein the heat conducting coil former is reinforced by the sleeve, the sleeve being made of high strength nonconducting material, the sleeve being attached with epoxy, the epoxy filling the slits in the heat conducting coil former and resulting in a hybrid structure.
8 . The voice coil speaker of claim 7 , wherein the high strength nonconducting material is at least one of glass or a carbon fiber composite.
9 . The conductively cooled voice coil speaker of claim 1 , wherein the thermal bridge comprises:
top attachment bars;
bottom attachment bars; and
flexible copper stranded wires that join the top attachment bars and the bottom attachment bars, wherein the flexible copper stranded wires conduct heat between the top attachment bars and the bottom attachment bars.
10 . The conductively cooled voice coil speaker of claim 1 , wherein the thermal bridge comprises:
a top attachment ring;
a bottom attachment ring; and
flexible copper stranded wires that join the top attachment ring and the bottom attachment ring, wherein the flexible copper stranded wires conduct heat between the top attachment ring and the bottom attachment ring.
11 . The conductively cooled voice coil speaker of claim 1 , wherein the thermal bridge comprises:
a top attachment ring;
a bottom attachment ring; and
flexible copper strips that join the top attachment ring and the bottom attachment ring, wherein the flexible copper strips conduct heat between the top attachment ring and the bottom attachment ring.
12 . The conductively cooled voice coil speaker of claim 1 , wherein the voice coil is surrounded on three of four sides by the heat conducting coil former.
13 . The conductively cooled voice coil speaker of claim 6 , wherein the plurality of axial slits have the same configuration along the groove of the heat conducting former such that the plurality of axial slits are configured to surround the voice coil on three sides and are covered by the sleeve on a fourth side.