One preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
The kitchen appliance of
A mixing implement in the form of a wire whisk 20 is shown extending downwardly from a front lower surface of the chamber 12 towards the mixing bowl seat 14. The implement is connected to the mixer by way of an orbital adapter 22 driven by an output shaft 44 of the mixer. The orbital adapter 22 drives the whisk 20 in a circle while rotating the whisk to give a thorough mixing of the ingredients in the mixing bowl. Use of an orbital adapter is optional and reduces the need to rotate the mixing bowl.
Inside the motor chamber 12 is a motor 24 and a gear box 26 as shown in
The gear train is more clearly shown in
The motor 24 is mounted horizontally in the chamber 12 such that the motor shaft 34 extends horizontally. Motor shaft 34 is provided with a worm 36. In this embodiment, the worm 36 is integrally formed with the motor shaft 34, although a separate worm cog could be pressed on and/or keyed to the shaft. The worm 38 has one or more teeth in the form of a helical thread. The worm 36 is directly engaged or meshed with a worm gear 38 which is mounted for rotation about a vertical axis and is pressed onto or otherwise mounted and keyed to an idler axle 40 for rotation therewith.
Mounted to the idler axle 40 below the worm gear 38 is an idler gear (not shown) which engages a driven cog 42 fitted to an output shaft 44 for rotation therewith. A bevel gear 46 is similarly mounted to the output shaft 44 above the driven cog 42 and meshes with a bevel gear 48 on a shaft 50 of the power take off 18.
The output shaft 44 extends through the bottom of the gear box 26 and chamber 12 to drive the implements directly or, as shown in the preferred embodiment, to drive the implements via the orbital adapter 22. The orbital adapter 22 may or may not be removably attached to the output shaft 44. The implements, such as the wire whisk 20 are connected to drive spigot 28 of the orbital adapter 22 in a quick connect manner, preferably by utilizing a radial pin 32 extending from the round shaft 30 and mating with a slot in the end of the implement in a bayonet type connection.
Worm gear 38 is shown in
The bottom of the teeth 54 also has a flat portion 62 and an arcuate portion 64 as shown in
In this way, the size of the gear box is not increased to accommodate the worm gear which is quieter and cheaper.
The shape of the teeth of the worm gear has been termed half arc as it is half flat and half arcuate. A full arc helical gear does give greater strength, however to manufacture a full arc gear requires the gear, once cast, to be machined to produce the arc in the teeth as these cannot be molded due to the groove in the radially outer surface. Such post mold machining increases the part cost significantly. However, the half arc gear can be directly molded or cast with no secondary machining process as there are no hidden recesses preventing the gear from leaving the mold cleanly.
The present stand mixer has a significantly reduced noise level at all speeds of operation compared to a prior art stand mixer.
The table below tabulates test results on noise levels using a prior art stand mixer and modifying only the worm gear. Sample 1 uses a modified gear box with a plastic half arc worm gear. Sample 2 uses a modified gear box with a bronze half arc worm gear and PA is the mixer using the unmodified gear box of the prior art.
As can be seen, at all 10 speeds, both samples produced significantly less noise with most reduction noticeable in the low to mid range speeds.
The embodiment described above is given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined in the appended claims.
Number | Date | Country | Kind |
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200610106473.5 | Jun 2006 | CN | national |